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Editor Work2015 Vol. 23, No. 5
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2015, 23(5): 809-820.
Abstract
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After twenty years of theoretical and practical research, the author proposes epistemology and methodology on prevention of geo-hazards in scientific philosophy. Geo-hazards are recognizable and can be controlled in epistemology. Since geo-hazards resulted from the unbalance of gravitational behaviors in soil or rock body, its commonality and particularity reflect different terms, such as geological body in the boundary, initial and excited conditions. For a specific situation, geo-hazards could be simplified to linear and definite problems which could be done in engineering control. Methodology for mitigation of geo-hazards can be used to obtain useful solution according to holism and reductionism, which promisingly use to develop the technical support system for public management of geological disasters reduction. The methods based on holism include synthesis, sum up, analogy, deduction, et al. Which can be applied to top or concept design of geo-hazards judgment in long time such as regional risk mapping, early warning and prevention plan. The methods based on reductionism include observation, description, analysis, modeling, evaluation, forecast and engineering control. It can be used to study area/case and its temporal state of slope problems, including geological information acquisition, identification of dangerous area and estimation, analysis of genesis, forecast or early-warning, analog simulation, project argumentation, risk assessment, decision-making support, et al.
After twenty years of theoretical and practical research, the author proposes epistemology and methodology on prevention of geo-hazards in scientific philosophy. Geo-hazards are recognizable and can be controlled in epistemology. Since geo-hazards resulted from the unbalance of gravitational behaviors in soil or rock body, its commonality and particularity reflect different terms, such as geological body in the boundary, initial and excited conditions. For a specific situation, geo-hazards could be simplified to linear and definite problems which could be done in engineering control. Methodology for mitigation of geo-hazards can be used to obtain useful solution according to holism and reductionism, which promisingly use to develop the technical support system for public management of geological disasters reduction. The methods based on holism include synthesis, sum up, analogy, deduction, et al. Which can be applied to top or concept design of geo-hazards judgment in long time such as regional risk mapping, early warning and prevention plan. The methods based on reductionism include observation, description, analysis, modeling, evaluation, forecast and engineering control. It can be used to study area/case and its temporal state of slope problems, including geological information acquisition, identification of dangerous area and estimation, analysis of genesis, forecast or early-warning, analog simulation, project argumentation, risk assessment, decision-making support, et al.
2015, 23(5): 821-826.
On the basis of the orthogonal experimental design of the ratio of similar materials, this paper prepares different composition and different mix ratios of similar material samples, and measures the thermal conductivity values of each sample.It examines the influences of the changes of moisture content, cement and sand-binder ratio upon the values of thermal conductivity. The results show that the change of moisture content in the samples has a significant impact on the value of thermal conductivity due to the significant difference between the respective thermal conductivity of water and air. The influence caused by the change of cement composition and ratio on the values of thermal conductivity can be ignored since the cement only accounts for a small proportion in the samples and the change of porosity is slightly caused by hydration. Under the interaction between sand and cement, cement composition and ratio can influence the effect of sand-binder ratio change upon thermal conductivity. When the cement consists of lime and gypsum, the factors affecting thermal conductivity are moisture content, sand-binder ratio, and cement composition. As the sand-binder ratio increases, the value of thermal conductivity can rise at a gradually decreasing growth rate. Yet when the cement consists of cement and gypsum, the factors affecting thermal conductivity are moisture content, cement composition, and sand-binder ratio. The change in thermal conductivity can be ignored as the sand-binder ratio increases.
On the basis of the orthogonal experimental design of the ratio of similar materials, this paper prepares different composition and different mix ratios of similar material samples, and measures the thermal conductivity values of each sample.It examines the influences of the changes of moisture content, cement and sand-binder ratio upon the values of thermal conductivity. The results show that the change of moisture content in the samples has a significant impact on the value of thermal conductivity due to the significant difference between the respective thermal conductivity of water and air. The influence caused by the change of cement composition and ratio on the values of thermal conductivity can be ignored since the cement only accounts for a small proportion in the samples and the change of porosity is slightly caused by hydration. Under the interaction between sand and cement, cement composition and ratio can influence the effect of sand-binder ratio change upon thermal conductivity. When the cement consists of lime and gypsum, the factors affecting thermal conductivity are moisture content, sand-binder ratio, and cement composition. As the sand-binder ratio increases, the value of thermal conductivity can rise at a gradually decreasing growth rate. Yet when the cement consists of cement and gypsum, the factors affecting thermal conductivity are moisture content, cement composition, and sand-binder ratio. The change in thermal conductivity can be ignored as the sand-binder ratio increases.
2015, 23(5): 827-834.
The highway slope of K48+722~800 in Jinping hydropower station is greatly affected by rainfall. The deep stability of this slope is related to the safety of the station project. On the basis of the experimental data, this paper uses Fredlund-Xing method to fit the SWCCs of the slope soils. The volumetric water content is used to represent the initial moist station of the soil. Then the evolution rules of pressure head, the influence of volumetric water content on pressure head and slope stability under rainfall conditions are researched numerically. The results show that, the pressure head at the slope surface and slip increases gradually at early rains. Then the area with increasing pressure head can expend toward the inside of slope body. For a period of time after rainfall, the pressure head of the slope surface and inferior region dissipates, while the pressure head of partial trailing area of slip increases. The pressure head would increase with the volumetric water content. And when the volumetric water content is little, the stability coefficient of slope can keep unchanging for a certain time and then slowly decreases. However, when volumetric water content increases, the stability coefficient of the slope can have an upward trend after rainfall.
The highway slope of K48+722~800 in Jinping hydropower station is greatly affected by rainfall. The deep stability of this slope is related to the safety of the station project. On the basis of the experimental data, this paper uses Fredlund-Xing method to fit the SWCCs of the slope soils. The volumetric water content is used to represent the initial moist station of the soil. Then the evolution rules of pressure head, the influence of volumetric water content on pressure head and slope stability under rainfall conditions are researched numerically. The results show that, the pressure head at the slope surface and slip increases gradually at early rains. Then the area with increasing pressure head can expend toward the inside of slope body. For a period of time after rainfall, the pressure head of the slope surface and inferior region dissipates, while the pressure head of partial trailing area of slip increases. The pressure head would increase with the volumetric water content. And when the volumetric water content is little, the stability coefficient of slope can keep unchanging for a certain time and then slowly decreases. However, when volumetric water content increases, the stability coefficient of the slope can have an upward trend after rainfall.
2015, 23(5): 835-843.
Liujiawan landslide is at Donghekou Hongguang town of Qingchuan county. The large rock landslide is triggered by Wenchuan earthquake in 2008. Field survey results show that the landslide deposit is different to the general Wenchuan earthquake landslide deposit. The landslide has the first destruction collapse along with division zones of carbonaceous slate and dolomite. The slip source region triggers a secondary collapse along with the dolomite weathering unloading zones. It takes the shape of two stacked stacking platforms and distinguishes between different lithologies. The lithology and weathering unloading belt show a significant power failure characteristic. The rock physical science experiment and wave velocity test of landslide deposit studies show that the hard outer soft rock slope is composed of dolomite, carbonaceous-slate and phyllite and has obvious differences in characteristics to quantify, differences lithologic of rock slope contact surface. Under earthquake conditions, dynamic mutation effect coupling projections terrain is the main factor that caused the slope failure. Closer study shows that landslide movement can be roughly divided into the following five dynamic processes including shattered mountain stage, geological interfacial stress mutation, high speed collapse, sturzstrom and accumulation, and secondary collapse slip stacking.
Liujiawan landslide is at Donghekou Hongguang town of Qingchuan county. The large rock landslide is triggered by Wenchuan earthquake in 2008. Field survey results show that the landslide deposit is different to the general Wenchuan earthquake landslide deposit. The landslide has the first destruction collapse along with division zones of carbonaceous slate and dolomite. The slip source region triggers a secondary collapse along with the dolomite weathering unloading zones. It takes the shape of two stacked stacking platforms and distinguishes between different lithologies. The lithology and weathering unloading belt show a significant power failure characteristic. The rock physical science experiment and wave velocity test of landslide deposit studies show that the hard outer soft rock slope is composed of dolomite, carbonaceous-slate and phyllite and has obvious differences in characteristics to quantify, differences lithologic of rock slope contact surface. Under earthquake conditions, dynamic mutation effect coupling projections terrain is the main factor that caused the slope failure. Closer study shows that landslide movement can be roughly divided into the following five dynamic processes including shattered mountain stage, geological interfacial stress mutation, high speed collapse, sturzstrom and accumulation, and secondary collapse slip stacking.
2015, 23(5): 844-849.
Many retaining structures of slopes are destructed by the Wenchuan earthquake. Seismic design must be reconsidered. Based on the performance of the slope, a supporting structure seismic design is proposed. The slope retaining structure seismic design should be in accordance with the requirements of the three-level fortify rules. They are as follows: a more severe earthquake, the slope in steady state, stability coefficient 1.2. Experience design earthquake, in stable state, the slope stability coefficient is 1.15. Confronted with severe earthquake, the slope in basic unstable state, the stability coefficient is 1.05. Using the seismic design principles, combined with strength reduction dynamics analysis method, a slope seismic design is given for example. The results show that the method proposed in this paper is simple to apply, and can be of great importance for slope structure seismic design.
Many retaining structures of slopes are destructed by the Wenchuan earthquake. Seismic design must be reconsidered. Based on the performance of the slope, a supporting structure seismic design is proposed. The slope retaining structure seismic design should be in accordance with the requirements of the three-level fortify rules. They are as follows: a more severe earthquake, the slope in steady state, stability coefficient 1.2. Experience design earthquake, in stable state, the slope stability coefficient is 1.15. Confronted with severe earthquake, the slope in basic unstable state, the stability coefficient is 1.05. Using the seismic design principles, combined with strength reduction dynamics analysis method, a slope seismic design is given for example. The results show that the method proposed in this paper is simple to apply, and can be of great importance for slope structure seismic design.
2015, 23(5): 850-855.
There are many landslides passed by faults. They are results from Wenchuan Ms 8.0 earthquake in 2008. Besides the movement of the seismogenic fault, its site effect can also influence the slope dynamic response and increase the slope instability. In this paper, the microtremors and seismic observations are performed along the front slope surface in Mianzhu Jiulong town. It uses the spectral ratio of horizontal to vertical components(H/V) of microtremor data and PGA amplification factors of acceleration records of two typical aftershocks, and obtains the spectral characteristic curves. By comparative analysis of the curves, it is found that: 1)with the growth of elevation, the values of PGA amplification factors decrease at first, and then increase, presenting aconcave shape. The concave-shape curves appear at the monitoring point around the fault zone. The values of PGA amplification factors can just reach to 0.4~1.0,while the values of PGA amplification factors at the monitoring point around the upper slope can even get to be 1.0~2.0. As the turning points appear around the fault zone, it shows the site effects of the fault from the geological view. 2)The NS/UD spectral ratio is generally greater than the EW/UD spectral ratio. The predominant frequency around the fault zone is near to the low frequency of 1Hz, smaller than any other monitoring point. It has the biggest spectral ratio of 3.0~4.0. It tells that the soil and rock of the surface rupture is loose and broken after the Wenchuan main shock. So the predominant frequency of the fault zone is low. The high frequencies of near-field aftershocks are filtered by the fault materials. Then the earthquake acceleration amplification coefficients are reduced as well. This study is helpful to enhance the understanding of the impact of the fault site effect on slope dynamic response.
There are many landslides passed by faults. They are results from Wenchuan Ms 8.0 earthquake in 2008. Besides the movement of the seismogenic fault, its site effect can also influence the slope dynamic response and increase the slope instability. In this paper, the microtremors and seismic observations are performed along the front slope surface in Mianzhu Jiulong town. It uses the spectral ratio of horizontal to vertical components(H/V) of microtremor data and PGA amplification factors of acceleration records of two typical aftershocks, and obtains the spectral characteristic curves. By comparative analysis of the curves, it is found that: 1)with the growth of elevation, the values of PGA amplification factors decrease at first, and then increase, presenting aconcave shape. The concave-shape curves appear at the monitoring point around the fault zone. The values of PGA amplification factors can just reach to 0.4~1.0,while the values of PGA amplification factors at the monitoring point around the upper slope can even get to be 1.0~2.0. As the turning points appear around the fault zone, it shows the site effects of the fault from the geological view. 2)The NS/UD spectral ratio is generally greater than the EW/UD spectral ratio. The predominant frequency around the fault zone is near to the low frequency of 1Hz, smaller than any other monitoring point. It has the biggest spectral ratio of 3.0~4.0. It tells that the soil and rock of the surface rupture is loose and broken after the Wenchuan main shock. So the predominant frequency of the fault zone is low. The high frequencies of near-field aftershocks are filtered by the fault materials. Then the earthquake acceleration amplification coefficients are reduced as well. This study is helpful to enhance the understanding of the impact of the fault site effect on slope dynamic response.
2015, 23(5): 856-865.
There are many earth fissures in Linfen Basin as it is a growing basin. Though detailed investigation, distribution and developmental status of the earth fissures are ascertained. Plane distribution features are summarized in this paper. Trench excavation has been conducted to understand the sectional structure features of earth fissures. The hazard of earth fissures is then summarized. A total of 86 earth fissures are mostly distributed in the Linfen depressed unit, Houma depressed unit, Xiangfen convex unit and other new tectonic units, which are accordant and correlative with the faults in underground. The basic characteristics are the plane distribution features, sectional structure features, motion features and activity features. Plane distribution characteristics are stability of trend, banding development, variety of plane distribution and differential development along trend. Sectional structure features are fault terrace shaped, Y-shaped, and pectination shaped. Motion features are lateral horizontal tension and vertical differential fracture. Activity features of earth fissures are movement interrupted and controlled by rainfall, differential activity and continue to expand. The deformation characteristic of surface is divided into shearing type and tension type. The damage forms are shown as wall cracking, roof cracking, stairs cracking and deformation of doors and windows.
There are many earth fissures in Linfen Basin as it is a growing basin. Though detailed investigation, distribution and developmental status of the earth fissures are ascertained. Plane distribution features are summarized in this paper. Trench excavation has been conducted to understand the sectional structure features of earth fissures. The hazard of earth fissures is then summarized. A total of 86 earth fissures are mostly distributed in the Linfen depressed unit, Houma depressed unit, Xiangfen convex unit and other new tectonic units, which are accordant and correlative with the faults in underground. The basic characteristics are the plane distribution features, sectional structure features, motion features and activity features. Plane distribution characteristics are stability of trend, banding development, variety of plane distribution and differential development along trend. Sectional structure features are fault terrace shaped, Y-shaped, and pectination shaped. Motion features are lateral horizontal tension and vertical differential fracture. Activity features of earth fissures are movement interrupted and controlled by rainfall, differential activity and continue to expand. The deformation characteristic of surface is divided into shearing type and tension type. The damage forms are shown as wall cracking, roof cracking, stairs cracking and deformation of doors and windows.
2015, 23(5): 866-885.
Daguangbao landslide is the largest landslide triggered by the Wenchuan MS 8.0 Earthquake on May 12, 2008. Its formation mechanism and kinematics attract a remained and wide attention of scholars at domestic and abroad. The paper is based on summary analysis of the engineering geological survey on the movement characteristics of landslide. The kinematics characteristics of the landslide is studied systematically. In addition, in order to reproduce the logical phenomenon in the process of sliding, physical model simulation is conducted for comparison. The results show the follows. The investigation and analysis of the slickenside, iconic features, vegetation, flat stone trend, slide cracks, and other topic features of the landslide accumulation determines the sliding direction, distance, velocity, motion eigenvalues and other movement characteristic parameters. The formation mechanism of landslide dust, blast shockwave, mixed lithology belt in the leading of slide tongue and clastic flow are systematic discussed. Landslide movement process physical simulation test confirms that Daguangbao landslide movement process has geological phenomenon such as cutting through of the front locking secting and enjection, blast shockwave, dust,suddeyly braking,significantly movement stage. Basically, its movement process can be dived into the following four stages, from quickly launching to high-speed sliding to suddenly braking and napping motion to detaching sliding on both sides of the accumulation.
Daguangbao landslide is the largest landslide triggered by the Wenchuan MS 8.0 Earthquake on May 12, 2008. Its formation mechanism and kinematics attract a remained and wide attention of scholars at domestic and abroad. The paper is based on summary analysis of the engineering geological survey on the movement characteristics of landslide. The kinematics characteristics of the landslide is studied systematically. In addition, in order to reproduce the logical phenomenon in the process of sliding, physical model simulation is conducted for comparison. The results show the follows. The investigation and analysis of the slickenside, iconic features, vegetation, flat stone trend, slide cracks, and other topic features of the landslide accumulation determines the sliding direction, distance, velocity, motion eigenvalues and other movement characteristic parameters. The formation mechanism of landslide dust, blast shockwave, mixed lithology belt in the leading of slide tongue and clastic flow are systematic discussed. Landslide movement process physical simulation test confirms that Daguangbao landslide movement process has geological phenomenon such as cutting through of the front locking secting and enjection, blast shockwave, dust,suddeyly braking,significantly movement stage. Basically, its movement process can be dived into the following four stages, from quickly launching to high-speed sliding to suddenly braking and napping motion to detaching sliding on both sides of the accumulation.
2015, 23(5): 886-895.
In order to better provide a theoretical basis for the treatment and prevention of the covered karst collapse(CKGC),according to the differences of material composition, geological structure, physical and mechanical properties of overburden on karst, for the first time, CKGC is divided into three types of mechanism, which are respectively called by hourglass type collapse, soil-cave type collapse and soft soil flow type collapse. In the distribution area of sandy soil, hourglass type collapse is caused by sand particles loss to the karst channels and karst caves because external factors triggering. Gravity and effective space provided by karst are necessary conditions for the occurrence of hourglass type collapse, and the role of groundwater accelerates the occurrence and shortens the process of hourglass type collapse. The ground subsidence phenomenon caused by soil-cave roof arching failure is called soil-cave type collapse occurring in clay and dense sand soil. The natural soil-cave is formed by three ways of the surface and groundwater erosion action, sand loss and soft soil flow. The roof of soil-cave is stable in the period of the formation and development of soil-cave, and ground subsidence occurs when the cave roof arching failure by triggering of external factors. The soil-cave type collapse has the characteristics of concealment and burst. The ground subsidence phenomenon caused by the soft soil flow is called as soft soil flow type collapse, is the result of the soft soil loss through karst channel and cave. The triggering factors of CKGC include groundwater action(vertical and horizontal seepage and underground water level frequent fluctuation at the soil/rock interface),external load(dynamic load and static load) and soil-cave roof resistance reduction(strength and thickness decrease and structure destruction of the roof).These external factors trigger the occurrence of CKGC.
In order to better provide a theoretical basis for the treatment and prevention of the covered karst collapse(CKGC),according to the differences of material composition, geological structure, physical and mechanical properties of overburden on karst, for the first time, CKGC is divided into three types of mechanism, which are respectively called by hourglass type collapse, soil-cave type collapse and soft soil flow type collapse. In the distribution area of sandy soil, hourglass type collapse is caused by sand particles loss to the karst channels and karst caves because external factors triggering. Gravity and effective space provided by karst are necessary conditions for the occurrence of hourglass type collapse, and the role of groundwater accelerates the occurrence and shortens the process of hourglass type collapse. The ground subsidence phenomenon caused by soil-cave roof arching failure is called soil-cave type collapse occurring in clay and dense sand soil. The natural soil-cave is formed by three ways of the surface and groundwater erosion action, sand loss and soft soil flow. The roof of soil-cave is stable in the period of the formation and development of soil-cave, and ground subsidence occurs when the cave roof arching failure by triggering of external factors. The soil-cave type collapse has the characteristics of concealment and burst. The ground subsidence phenomenon caused by the soft soil flow is called as soft soil flow type collapse, is the result of the soft soil loss through karst channel and cave. The triggering factors of CKGC include groundwater action(vertical and horizontal seepage and underground water level frequent fluctuation at the soil/rock interface),external load(dynamic load and static load) and soil-cave roof resistance reduction(strength and thickness decrease and structure destruction of the roof).These external factors trigger the occurrence of CKGC.
2015, 23(5): 896-901.
Soil deformation monitoring plays an important role in damage prevention of land deformation. In this paper, distributed monitoring model tests using airbag method are carried out to study the development of land deformation. The technical principles and test program of distributed fiber optic monitoring are introduced and the monitoring results under different conditions are analyzed. These results indicate that the distributed optical fiber monitoring technology can be effectively used to the deformation monitoring of soil under different conditions. The formation of arched area and land deformation can be located by thesaddle type strain distribution curve. This technology can be applied to monitor the soil deformation during the development of land deformation.
Soil deformation monitoring plays an important role in damage prevention of land deformation. In this paper, distributed monitoring model tests using airbag method are carried out to study the development of land deformation. The technical principles and test program of distributed fiber optic monitoring are introduced and the monitoring results under different conditions are analyzed. These results indicate that the distributed optical fiber monitoring technology can be effectively used to the deformation monitoring of soil under different conditions. The formation of arched area and land deformation can be located by thesaddle type strain distribution curve. This technology can be applied to monitor the soil deformation during the development of land deformation.
2015, 23(5): 902-909.
This paper studies the influence that the properties of structural plane can make on the material properties of rock mass at Jinping site. A series of indoor triaxial compression tests are carried out. Based on the test results, four groups of numerical simulation tests for the influence that structural plane traits can make on rock mass mechanics properties are made out. Finally the instance of the slope excavation is numerically simulated. The indoor test results show that the rock failure process can be divided into four typical phases: elastic deformation stage, the yield stage, residual strength and plastic flow phase. As the confining pressure increases, the rock damage deviatoric stress increases gradually and shows the ductility properties gradually. Structural plane simulation results show that weak-filling structural planes have a larger degradation on rock mechanics properties than no-filling structure planes. The structure planes with a dip angle have larger degradation on rock mechanics properties than structure planes which the zero dip angle. Structure planes that have a larger dip angle have a larger influence on rock mechanics properties than the small dip angle's, and weak-filling thickness have a larger influence on internal friction angle of rock mass. Examples of simulation results show that excavation unloading causes the rebound deformation trailing edge of slope rock mass, and tensile displacements of X direction have developed in slope. Plastic zones extend along the lamprophyric vein which is a weak field. When the excavation is to 8 phase, lamprophyric vein is a plastic penetration area, which mean the slope is instable. The research results have certain guiding significance on excavation stability evaluation of high steep slope rock mass.
This paper studies the influence that the properties of structural plane can make on the material properties of rock mass at Jinping site. A series of indoor triaxial compression tests are carried out. Based on the test results, four groups of numerical simulation tests for the influence that structural plane traits can make on rock mass mechanics properties are made out. Finally the instance of the slope excavation is numerically simulated. The indoor test results show that the rock failure process can be divided into four typical phases: elastic deformation stage, the yield stage, residual strength and plastic flow phase. As the confining pressure increases, the rock damage deviatoric stress increases gradually and shows the ductility properties gradually. Structural plane simulation results show that weak-filling structural planes have a larger degradation on rock mechanics properties than no-filling structure planes. The structure planes with a dip angle have larger degradation on rock mechanics properties than structure planes which the zero dip angle. Structure planes that have a larger dip angle have a larger influence on rock mechanics properties than the small dip angle's, and weak-filling thickness have a larger influence on internal friction angle of rock mass. Examples of simulation results show that excavation unloading causes the rebound deformation trailing edge of slope rock mass, and tensile displacements of X direction have developed in slope. Plastic zones extend along the lamprophyric vein which is a weak field. When the excavation is to 8 phase, lamprophyric vein is a plastic penetration area, which mean the slope is instable. The research results have certain guiding significance on excavation stability evaluation of high steep slope rock mass.
2015, 23(5): 910-917.
Mudstone, shale and sandstone contaminated with heavy metals are studied with shear strength test, endurance strength test, resistant to disintegration test and point loading test. According to the results, the relationship curves of compressive strength and heavy metal content are drawn. The relationship between compressive strength of the rock and mass ratio of heavy metals is analyzed with linear regression method. The results show that the mechanical strength of the three contaminated rocks decreases with the increasing of heavy metal content under the same conditions such as lithology, water content, and test condition. The relationship between uniaxial compressive strength and mass ratio of heavy metals is a logarithmic function for contaminated mudstone and sandstone and power function for contaminated shale. The differentiation of relationship is a more significant or significant negative correlation. The equations of intrusion and extension performances are established according Weibull distribution law and convection-diffusion characteristic. The test results of mudstone are calculated. The curves between intrusive performance, extended performance and time are drawn. The results show that the average order of intrusive performance and extended performance of four metal elements in shale is Cd2+ Pb2+ Cu2+ Zn2+. The element activity is greater, the invasive capacity and extended capacity are stronger. The intrusion performance gradually decreases and the extended performance gradually increases with changing time.
Mudstone, shale and sandstone contaminated with heavy metals are studied with shear strength test, endurance strength test, resistant to disintegration test and point loading test. According to the results, the relationship curves of compressive strength and heavy metal content are drawn. The relationship between compressive strength of the rock and mass ratio of heavy metals is analyzed with linear regression method. The results show that the mechanical strength of the three contaminated rocks decreases with the increasing of heavy metal content under the same conditions such as lithology, water content, and test condition. The relationship between uniaxial compressive strength and mass ratio of heavy metals is a logarithmic function for contaminated mudstone and sandstone and power function for contaminated shale. The differentiation of relationship is a more significant or significant negative correlation. The equations of intrusion and extension performances are established according Weibull distribution law and convection-diffusion characteristic. The test results of mudstone are calculated. The curves between intrusive performance, extended performance and time are drawn. The results show that the average order of intrusive performance and extended performance of four metal elements in shale is Cd2+ Pb2+ Cu2+ Zn2+. The element activity is greater, the invasive capacity and extended capacity are stronger. The intrusion performance gradually decreases and the extended performance gradually increases with changing time.
2015, 23(5): 918-923.
At present, the study of rock structural surface roughness is often confined to the earth's surface. So, it is difficult to reflect the characteristics of the deep rock joints roughness. The drill wall joint profile contains the characteristics of 3D information. This paper has carried out the research of fractal characteristics of rock joints roughness based on the digital borehole camera technology, obtained panorama of underground drilling rock joints using digital camera system, extracted rock joint contour line using edge detection technology, then got the real rough surface contour by space transformation and distance transformation. This paper has got the JRC value of rock joint contour line by compared with the 10 contour line profile curve which Barton had put forward and calculate their fractal dimensions. According to the principle of least squares method, we can fit the relationship between the fractal dimension and JRC and that is (D)=JRC=-541.9x2+1362x-818.53. This paper has provided the basis for describing the structure and characteristics of the deep-seated natural joint. The results is important significance because it is meaningful for the more in-depth study about the surface of the rock joint which is located in deep underground.
At present, the study of rock structural surface roughness is often confined to the earth's surface. So, it is difficult to reflect the characteristics of the deep rock joints roughness. The drill wall joint profile contains the characteristics of 3D information. This paper has carried out the research of fractal characteristics of rock joints roughness based on the digital borehole camera technology, obtained panorama of underground drilling rock joints using digital camera system, extracted rock joint contour line using edge detection technology, then got the real rough surface contour by space transformation and distance transformation. This paper has got the JRC value of rock joint contour line by compared with the 10 contour line profile curve which Barton had put forward and calculate their fractal dimensions. According to the principle of least squares method, we can fit the relationship between the fractal dimension and JRC and that is (D)=JRC=-541.9x2+1362x-818.53. This paper has provided the basis for describing the structure and characteristics of the deep-seated natural joint. The results is important significance because it is meaningful for the more in-depth study about the surface of the rock joint which is located in deep underground.
2015, 23(5): 924-929.
This paper looks for the links between the coal fracture degree and the electricity released by the raw coal sample to improve the forecasting accuracy of mine dynamic disaster. The self-developed charge sensor is used to conduct charge induction test with the raw coal sample under triaxial compression. It analyzes the charge induction signal variation characteristics of coal with different fracture degrees in adjacent sides. Using FFT method, the spectrum of the charge-induced signal is processed to study the change rules of the spectrum caused by different gas pore pressures in frequency domain. The charge accumulation quantity is analyzed comparing with the cumulative ringing counts and the total acoustic emission energy on this basis. The research results show that the more serious the coal fracture degree is,the charge induction signal is more abundant. As the pore pressure increases, the largest peak of the charge induction signal frequency amplitude moves to low frequencies under the fixed confining pressure. The frequency of the charge induction signal is generally in 200Hz below. The frequency of the large amplitude appears less than 50Hz under the triaxial compressions. The charge accumulation quantity shows greater jump growth trend. The cumulative amount of the charge induction signal amplitude is smaller in comparison with the cumulative ringing counts and the total acoustic emission energy.
This paper looks for the links between the coal fracture degree and the electricity released by the raw coal sample to improve the forecasting accuracy of mine dynamic disaster. The self-developed charge sensor is used to conduct charge induction test with the raw coal sample under triaxial compression. It analyzes the charge induction signal variation characteristics of coal with different fracture degrees in adjacent sides. Using FFT method, the spectrum of the charge-induced signal is processed to study the change rules of the spectrum caused by different gas pore pressures in frequency domain. The charge accumulation quantity is analyzed comparing with the cumulative ringing counts and the total acoustic emission energy on this basis. The research results show that the more serious the coal fracture degree is,the charge induction signal is more abundant. As the pore pressure increases, the largest peak of the charge induction signal frequency amplitude moves to low frequencies under the fixed confining pressure. The frequency of the charge induction signal is generally in 200Hz below. The frequency of the large amplitude appears less than 50Hz under the triaxial compressions. The charge accumulation quantity shows greater jump growth trend. The cumulative amount of the charge induction signal amplitude is smaller in comparison with the cumulative ringing counts and the total acoustic emission energy.
2015, 23(5): 930-936.
The materials of municipal solid waste(MSW)can be divided into three parts. They are respectively the materials of easily degradation, difficulty degradation, and incompressibility. Their proportions are 50%, 15%, and 35%,respectively. Their shear strength properties and parameters are examined with an ultra-large direct shear test equipment. The artificial MSW is tested in a geo-environmental laboratory. The test results show that the compression time and shear strain are two key factors for MSW shear strength. The relationship between the shear strength and the vertical pressure applied on the test samples conforms to follow the frictional law of Mohr-Coulomb. Besides, the shear strength parameters of MSW are obtained with the initial void ratio equaling 2.9 under different compression times and different shear strains. The cohesion varies from 9.69 to 15.64kPa. The internal friction angle varies from 18.73to 35.53.
The materials of municipal solid waste(MSW)can be divided into three parts. They are respectively the materials of easily degradation, difficulty degradation, and incompressibility. Their proportions are 50%, 15%, and 35%,respectively. Their shear strength properties and parameters are examined with an ultra-large direct shear test equipment. The artificial MSW is tested in a geo-environmental laboratory. The test results show that the compression time and shear strain are two key factors for MSW shear strength. The relationship between the shear strength and the vertical pressure applied on the test samples conforms to follow the frictional law of Mohr-Coulomb. Besides, the shear strength parameters of MSW are obtained with the initial void ratio equaling 2.9 under different compression times and different shear strains. The cohesion varies from 9.69 to 15.64kPa. The internal friction angle varies from 18.73to 35.53.
2015, 23(5): 937-942.
Dynamic motel test has been widely applied to the study of soil-structure interaction, in which the preparation of model soil matters the most. This paper prepares samples with foil sampler of different dry densities and water contents according to the soil physical properties, and then subjects the samples to direct shear test to get the original shear modulus. Considering the results, the correlation between the original shear modulus and the soil dry density and water content is analyzed. The request of the preparation of model soil is obtained on the basis of similitude law in dynamic model test. The preparation of model soil without other materials is analyzed through with above findings. Then a qualitative way of the preparation of model soil is obtained. It can provide useful and helpful directions for the preparation of model soil in similar test.
Dynamic motel test has been widely applied to the study of soil-structure interaction, in which the preparation of model soil matters the most. This paper prepares samples with foil sampler of different dry densities and water contents according to the soil physical properties, and then subjects the samples to direct shear test to get the original shear modulus. Considering the results, the correlation between the original shear modulus and the soil dry density and water content is analyzed. The request of the preparation of model soil is obtained on the basis of similitude law in dynamic model test. The preparation of model soil without other materials is analyzed through with above findings. Then a qualitative way of the preparation of model soil is obtained. It can provide useful and helpful directions for the preparation of model soil in similar test.
2015, 23(5): 943-947.
At present, there is limited study on the relationship between Duncan-Chang constitutive model parameters and the saturation of collapsing loess. This paper uses the consolidated drained triaxial shear test on Jinnan collapsing loess. It studies the law of saturation for the Duncan-Chang model parameters. The results show that when the confining pressure increases, the stress-strain curves change from the weak hardening into strength hardening, and the volume changes also increase. The model parameters of C、、K、G、F、D、Rf can decrease as the saturation increases. But the model parameter n can increase as the saturation increases. The curve fitting is good.
At present, there is limited study on the relationship between Duncan-Chang constitutive model parameters and the saturation of collapsing loess. This paper uses the consolidated drained triaxial shear test on Jinnan collapsing loess. It studies the law of saturation for the Duncan-Chang model parameters. The results show that when the confining pressure increases, the stress-strain curves change from the weak hardening into strength hardening, and the volume changes also increase. The model parameters of C、、K、G、F、D、Rf can decrease as the saturation increases. But the model parameter n can increase as the saturation increases. The curve fitting is good.
2015, 23(5): 948-953.
There are complex hydrothermal processes in the atmosphere, the ground surface and the frozen soil. Precipitation is the main source of water supply on Qinghai-Tibetan Plateau, forms a discontinuous change layer of hydrothermal in the shallow ground. We analyze the temperature changes under the difference ground surface at different precipitation times. We use the in-situ monitoring data of precipitation and the temperature in the shallow ground from 0 to 80cm in depth under the engineering pavement(asphalt and gravel pavement) and the natural ground(alpine steppe and alpine meadow).The results show the follows. Annual precipitation is increased every year in Beiluhe area. The increase rate is 22.9mma-1. Precipitation mainly concentrates in 5~9months. Response to temperature during daytime is intense than that at night for precipitation. Temperature change under engineering pavement is greater than that under natural ground at night. Under the same precipitation condition, temperature variations in 10 :00~15:30 duration is greater than those in 16 :00~18:00. As the precipitation increases, the decrease of temperature increases. The depth of temperature response to the precipitation is 0~30cm deep range of gravel pavement, alpine steppe, and alpine meadow. The influence depth of asphalt pavement is 0~20cm deep range. Affected by the impermeable layer of pavement, and magnitude of the temperature at 5cm depth is greater than that at the surface. This study provides data to divide the different heat transfer mode stratification under different ground surfaces.
There are complex hydrothermal processes in the atmosphere, the ground surface and the frozen soil. Precipitation is the main source of water supply on Qinghai-Tibetan Plateau, forms a discontinuous change layer of hydrothermal in the shallow ground. We analyze the temperature changes under the difference ground surface at different precipitation times. We use the in-situ monitoring data of precipitation and the temperature in the shallow ground from 0 to 80cm in depth under the engineering pavement(asphalt and gravel pavement) and the natural ground(alpine steppe and alpine meadow).The results show the follows. Annual precipitation is increased every year in Beiluhe area. The increase rate is 22.9mma-1. Precipitation mainly concentrates in 5~9months. Response to temperature during daytime is intense than that at night for precipitation. Temperature change under engineering pavement is greater than that under natural ground at night. Under the same precipitation condition, temperature variations in 10 :00~15:30 duration is greater than those in 16 :00~18:00. As the precipitation increases, the decrease of temperature increases. The depth of temperature response to the precipitation is 0~30cm deep range of gravel pavement, alpine steppe, and alpine meadow. The influence depth of asphalt pavement is 0~20cm deep range. Affected by the impermeable layer of pavement, and magnitude of the temperature at 5cm depth is greater than that at the surface. This study provides data to divide the different heat transfer mode stratification under different ground surfaces.
2015, 23(5): 954-958.
This paper examines the Lishi loess of Guanzhong region. It develops a soil disintegration test instrument for doing the flooding experiment of indoor small size. It measures soil disintegration process parameters to explore Lishi loess rate characteristics of disintegration in the region. It aims to offer a reference for time prediction of Lishi loess slope instability in the region. The results reveal some phenomena and laws of the disintegration process. Under different flooding conditions, the whole process of Lishi loess can be divided into rapid disintegration stage from the experiment beginning to formulate flooding depth and disintegration stabilization phase after flooding water. Loess body size has a certain relationship with rate of disintegration, the immersion depth and contact area. The rates of disintegration have broken line relationship with time. The disintegration rate is reduced rapidly to about 0.21~0.25kgmin-1 after a peak from the experiment beginning to formulate flooding depth. Then the disintegration rate is fixed in 0.08~0.14kgmin-1 until after flooding water stability. When loess sampling extent of flooding is fixed, with the increase of immersion depth, the stabilization of the soil disintegration rate increases linearly, and presents a linear correlation.
This paper examines the Lishi loess of Guanzhong region. It develops a soil disintegration test instrument for doing the flooding experiment of indoor small size. It measures soil disintegration process parameters to explore Lishi loess rate characteristics of disintegration in the region. It aims to offer a reference for time prediction of Lishi loess slope instability in the region. The results reveal some phenomena and laws of the disintegration process. Under different flooding conditions, the whole process of Lishi loess can be divided into rapid disintegration stage from the experiment beginning to formulate flooding depth and disintegration stabilization phase after flooding water. Loess body size has a certain relationship with rate of disintegration, the immersion depth and contact area. The rates of disintegration have broken line relationship with time. The disintegration rate is reduced rapidly to about 0.21~0.25kgmin-1 after a peak from the experiment beginning to formulate flooding depth. Then the disintegration rate is fixed in 0.08~0.14kgmin-1 until after flooding water stability. When loess sampling extent of flooding is fixed, with the increase of immersion depth, the stabilization of the soil disintegration rate increases linearly, and presents a linear correlation.
2015, 23(5): 959-964.
The properties of creep and time dependent behaviours of strength of weak intercalated soils in soft rock of Badong formation are obvious. To study the long-term strength of weak intercalated soils can be useful for stability analysis of the cutting slopes with weak intercalated soils. In order to study the long-term strength of the weak intercalated soils, the strength and creep tests of weak intercalated soils are carried out with a GDS unsaturated triaxial apparatus. It is to find out the effects of matrix suction on strength and creep characteristics of weak intercalated soils from the stress-strain and strain-time curves. Then the isochronous curves method is used to determine the long-term strength of weak intercalated soils based on the creep curves. The results show that the long-term strength of weak intercalated soils is reduced greatly in comparison with the instantaneous strength. The loss rate of strength is between 34% and 62%.The smaller the matrix suction is,the smaller the long-term strength and the greater the loss rate of strength can be. That is to say for the weak intercalated soils of soft rock of Badong formation, the higher the saturability is,the smaller the strength is and the greater the loss rate of strength is.The increasing range of loss rate of strength can increase with the increasing of saturability of weak intercalated soils.
The properties of creep and time dependent behaviours of strength of weak intercalated soils in soft rock of Badong formation are obvious. To study the long-term strength of weak intercalated soils can be useful for stability analysis of the cutting slopes with weak intercalated soils. In order to study the long-term strength of the weak intercalated soils, the strength and creep tests of weak intercalated soils are carried out with a GDS unsaturated triaxial apparatus. It is to find out the effects of matrix suction on strength and creep characteristics of weak intercalated soils from the stress-strain and strain-time curves. Then the isochronous curves method is used to determine the long-term strength of weak intercalated soils based on the creep curves. The results show that the long-term strength of weak intercalated soils is reduced greatly in comparison with the instantaneous strength. The loss rate of strength is between 34% and 62%.The smaller the matrix suction is,the smaller the long-term strength and the greater the loss rate of strength can be. That is to say for the weak intercalated soils of soft rock of Badong formation, the higher the saturability is,the smaller the strength is and the greater the loss rate of strength is.The increasing range of loss rate of strength can increase with the increasing of saturability of weak intercalated soils.
2015, 23(5): 965-970.
The percolation phenomena, which are that with some kind of critical factor changing, the original properties of the object will sudden change, widely exist in nature. And when the changing is happening, the value of the critical factor is the percolation threshold. The percolation phenomena also exist in the process of rock damaging and failure and the percolation threshold can be studied by renormalization group approach. Assumed that the failure of red-layer soft rock cased by the failure of cement in structure. And according to the microscopic structure of silty mudstone, one kind of red-layer soft rock, can build the renormalization group model of red-layer soft rock. In order to facilitate the calculation, the rules of renormalization transformation set simply. Then the percolation threshold of red-layer soft rock failure under loading condition can be calculated by the renormalization group approach. When the damage extent of red-layer soft rock failure under loading condition reached the percolation threshold, the inner structure will damage in large-scale and the strength will drop rapidly. The random damage of red-layer soft rock change into ordered damage, the velocity of damage becomes faster.
The percolation phenomena, which are that with some kind of critical factor changing, the original properties of the object will sudden change, widely exist in nature. And when the changing is happening, the value of the critical factor is the percolation threshold. The percolation phenomena also exist in the process of rock damaging and failure and the percolation threshold can be studied by renormalization group approach. Assumed that the failure of red-layer soft rock cased by the failure of cement in structure. And according to the microscopic structure of silty mudstone, one kind of red-layer soft rock, can build the renormalization group model of red-layer soft rock. In order to facilitate the calculation, the rules of renormalization transformation set simply. Then the percolation threshold of red-layer soft rock failure under loading condition can be calculated by the renormalization group approach. When the damage extent of red-layer soft rock failure under loading condition reached the percolation threshold, the inner structure will damage in large-scale and the strength will drop rapidly. The random damage of red-layer soft rock change into ordered damage, the velocity of damage becomes faster.
2015, 23(5): 971-975.
The infiltration of water through wall cake pore under the effect of fluid pressure is the cause of instability of water sensitive formations during drilling process. In order to better understand the laws of infiltration, infiltration test is conducted under different fluid pressures. The test results show that when infiltration time is the same, the infiltration water increases first and then decreases with increasing of fluid pressure. When fluid pressure is the same, the infiltration rate decreases with increasing of time and eventually tends to a stable value. The stable value of infiltration rate has a low correlation with fluid pressure. When fluid pressure is different, the proportion of previous infiltration volume and the cake mass(under dry conditions) increase with increasing of fluid pressure. Infiltration of water increases first and then decreases with increasing of cake mass. The results of the test can provide reference for evaluation and control of fluid infiltration.
The infiltration of water through wall cake pore under the effect of fluid pressure is the cause of instability of water sensitive formations during drilling process. In order to better understand the laws of infiltration, infiltration test is conducted under different fluid pressures. The test results show that when infiltration time is the same, the infiltration water increases first and then decreases with increasing of fluid pressure. When fluid pressure is the same, the infiltration rate decreases with increasing of time and eventually tends to a stable value. The stable value of infiltration rate has a low correlation with fluid pressure. When fluid pressure is different, the proportion of previous infiltration volume and the cake mass(under dry conditions) increase with increasing of fluid pressure. Infiltration of water increases first and then decreases with increasing of cake mass. The results of the test can provide reference for evaluation and control of fluid infiltration.
2015, 23(5): 976-981.
This paper examines the deficiency in research about the contact pressure of current lattice beam internal force calculation methods. It carries out the study of a 1:2 large-scale physical model test and analyzes the distribution of foundation counterforce. The result indicates that the distribution of beam contact pressure is not uniform. For horizontal beam, the foundation counterforce near node is stronger than that in the middle segment of the beam. For vertical beam, the reaction appears to be a trapezoidal distribution with top weaker and this trend is more obvious with the loading. The contact pressure of each horizontal beam is equal in prestressing stage while it appears a distribution as the vertical beam in landslide developing stage. There is a certain proportion relationship between the span reaction of vertical beams and that of the corresponding horizontal beam span. The coefficient of proportionality is between 0.4 and 0.6. The reaction force is all different among the angle node, the edge node and the center node. It is the strongest at the angle node. The edge node comes the second. The center node weakest. Their proportions are 2.15:1.15:1.00.
This paper examines the deficiency in research about the contact pressure of current lattice beam internal force calculation methods. It carries out the study of a 1:2 large-scale physical model test and analyzes the distribution of foundation counterforce. The result indicates that the distribution of beam contact pressure is not uniform. For horizontal beam, the foundation counterforce near node is stronger than that in the middle segment of the beam. For vertical beam, the reaction appears to be a trapezoidal distribution with top weaker and this trend is more obvious with the loading. The contact pressure of each horizontal beam is equal in prestressing stage while it appears a distribution as the vertical beam in landslide developing stage. There is a certain proportion relationship between the span reaction of vertical beams and that of the corresponding horizontal beam span. The coefficient of proportionality is between 0.4 and 0.6. The reaction force is all different among the angle node, the edge node and the center node. It is the strongest at the angle node. The edge node comes the second. The center node weakest. Their proportions are 2.15:1.15:1.00.
2015, 23(5): 982-988.
This paper aims to improve the brittle fracture characteristics of cement soil and to study the engineering properties and mechanical mechanism of asbestos fiber reinforced soft soil. It adds the asbestos fiber into fly ash and cement soil. Thus it creates a new kind of composite soil and carries out a series of experiments on the new soil. In these experiments, asbestos fiber is added into fly ash and cement soil with different ratios(0%~9%),which results in different composite soil samples with different content of asbestos fiber. All of the composite soil samples are subjected to the direct shear test, the unconfined compression test, the diametral compression test and the scanning electron microscopy test(SEM).Thus the mechanical behavior and mechanism of fiber reinforced soft soil are illustrated. It is found that the combination of asbestos fiber and fly-ash cement can significantly enhance the strength and stability of soft soil and improve brittle fracture characteristics of cement soil. There is a range of optimal content of asbestos fiber regarding the enhancement of the strength value of the composite soil. This range is between 3%~6%. Other asbestos fiber content outside the range can reduce the enhancement effect.
This paper aims to improve the brittle fracture characteristics of cement soil and to study the engineering properties and mechanical mechanism of asbestos fiber reinforced soft soil. It adds the asbestos fiber into fly ash and cement soil. Thus it creates a new kind of composite soil and carries out a series of experiments on the new soil. In these experiments, asbestos fiber is added into fly ash and cement soil with different ratios(0%~9%),which results in different composite soil samples with different content of asbestos fiber. All of the composite soil samples are subjected to the direct shear test, the unconfined compression test, the diametral compression test and the scanning electron microscopy test(SEM).Thus the mechanical behavior and mechanism of fiber reinforced soft soil are illustrated. It is found that the combination of asbestos fiber and fly-ash cement can significantly enhance the strength and stability of soft soil and improve brittle fracture characteristics of cement soil. There is a range of optimal content of asbestos fiber regarding the enhancement of the strength value of the composite soil. This range is between 3%~6%. Other asbestos fiber content outside the range can reduce the enhancement effect.
2015, 23(5): 989-995.
Shengli oil fields are one of the most important petroleum occurring areas. Its geothermal resources are abundant. With the background of energy saving, wastewater from petroleum producing is of relatively high-temperature. It can be used for water flooding, space heating and bathing. Wastewater samples from 19 typical oil production stations of seven oil factories in Shengli oil fields are obtained. Water chemical compositions are analyzed by ion chromatography. Scaling tendency corrosion of wastewater are also discussed. Results show that the pH of wastewater is 6.8-8.0 and the average is 7.4. It is saline water-brine with TDS ranging from 6.0gL-1 to 59.7gL-1. The wastewater is rich in Li, Mn, Cr, Ni, Cu, Zn and Sr. The microelements of Li and Sr are in particular rich. Its average concentrations are 1mgL-1 and 70.5mgL-1,which satisfy the mineral water requirement but cannot be used for minerals exploitation. Corrosive efficiency factor, larson and reruo method are used to assess the corrosion of wastewater. Results indicate that the wastewater is strongly corrosive, which is caused by chloride ion. Carbonate, sulfate and silicate scale are assessed using references from GB-T-11615-2010. The results indicate that carbonate and silicate scale won't occur while sulfate scale would form in wastewater from Binnan and Hekou oil production plant and pretreatment should be done before integrated utilization. Based on suggestions from published papers on wastewater utilization and local requirement, it can be used for water flooding, space heating, bathing, hothouse and aquaculture, which can mitigate environmental pollution and improve energy structure, showing favorable social and economic benefits. When using the wastewater, its corrosion and scaling tendency must be considered and choose proper pretreatment and pipeline.
Shengli oil fields are one of the most important petroleum occurring areas. Its geothermal resources are abundant. With the background of energy saving, wastewater from petroleum producing is of relatively high-temperature. It can be used for water flooding, space heating and bathing. Wastewater samples from 19 typical oil production stations of seven oil factories in Shengli oil fields are obtained. Water chemical compositions are analyzed by ion chromatography. Scaling tendency corrosion of wastewater are also discussed. Results show that the pH of wastewater is 6.8-8.0 and the average is 7.4. It is saline water-brine with TDS ranging from 6.0gL-1 to 59.7gL-1. The wastewater is rich in Li, Mn, Cr, Ni, Cu, Zn and Sr. The microelements of Li and Sr are in particular rich. Its average concentrations are 1mgL-1 and 70.5mgL-1,which satisfy the mineral water requirement but cannot be used for minerals exploitation. Corrosive efficiency factor, larson and reruo method are used to assess the corrosion of wastewater. Results indicate that the wastewater is strongly corrosive, which is caused by chloride ion. Carbonate, sulfate and silicate scale are assessed using references from GB-T-11615-2010. The results indicate that carbonate and silicate scale won't occur while sulfate scale would form in wastewater from Binnan and Hekou oil production plant and pretreatment should be done before integrated utilization. Based on suggestions from published papers on wastewater utilization and local requirement, it can be used for water flooding, space heating, bathing, hothouse and aquaculture, which can mitigate environmental pollution and improve energy structure, showing favorable social and economic benefits. When using the wastewater, its corrosion and scaling tendency must be considered and choose proper pretreatment and pipeline.
2015, 23(5): 996-1004.
The mechanical behavior of Tianjin marine soft soil can't meet the requirement of engineering construction, but it can be enhanced effectively by curing agents. Moreover when curing agents and additional agent are added in the soft soil together, the strength of the stabilized soil can be improved further. For this reason, the method of combing lime and cement or gypsum is proposed in this paper. In the test the unconfined compressive strength of solidified soil is used as a criterion to identify the solidifying effect. Meanwhile, sample microstructure is analyzed with SEM and the unconfined compressive strength of destroyed and re-cured samples is measured and recorded. Test and analysis results indicate that the optimum content of cement only changes with the different dosage of lime. For example, if the content of cement in stabilized soil adding 12% lime is less than 3%,the effect of solidification is the best. Gypsum can't improve the soil strength. It even makes the water stability of soil badly and causes the soil crack under the influence of water. Although the compressibility of both lime stabilized soil with and without additional agent is low, their various mechanical properties can be improved obviously. Their failure mode is the brittle failure. The strength of destroyed soil is very low and can't recovery, to which attention should be given in practice. Microstructure analysis shows that the C-S-H(hydrated calcium silicate),acicular ettringite, CaCO3 and Ca(OH)2 crystal formed in soil can fill pores and cement particles. Effective and proper product is beneficial to improve the strength of stabilized soil. The total of pores and particles in solidified soil increases with the augment of the pressure, however, area of pore, equivalent diameter of both pores and particles decreases with the augment of pressure.
The mechanical behavior of Tianjin marine soft soil can't meet the requirement of engineering construction, but it can be enhanced effectively by curing agents. Moreover when curing agents and additional agent are added in the soft soil together, the strength of the stabilized soil can be improved further. For this reason, the method of combing lime and cement or gypsum is proposed in this paper. In the test the unconfined compressive strength of solidified soil is used as a criterion to identify the solidifying effect. Meanwhile, sample microstructure is analyzed with SEM and the unconfined compressive strength of destroyed and re-cured samples is measured and recorded. Test and analysis results indicate that the optimum content of cement only changes with the different dosage of lime. For example, if the content of cement in stabilized soil adding 12% lime is less than 3%,the effect of solidification is the best. Gypsum can't improve the soil strength. It even makes the water stability of soil badly and causes the soil crack under the influence of water. Although the compressibility of both lime stabilized soil with and without additional agent is low, their various mechanical properties can be improved obviously. Their failure mode is the brittle failure. The strength of destroyed soil is very low and can't recovery, to which attention should be given in practice. Microstructure analysis shows that the C-S-H(hydrated calcium silicate),acicular ettringite, CaCO3 and Ca(OH)2 crystal formed in soil can fill pores and cement particles. Effective and proper product is beneficial to improve the strength of stabilized soil. The total of pores and particles in solidified soil increases with the augment of the pressure, however, area of pore, equivalent diameter of both pores and particles decreases with the augment of pressure.
2015, 23(5): 1005-1012.
The bearing capacity of circular footing is studied using critical slip field method. The three factors under different earth pressures are presented in the form of tables and curves. Recursion formula is deduced according to the force equilibrium conditions of slice. Firstly, the soil in the calculation range that had been assumed previously can be divided into a series of slices and state points. Secondly, the parameters of all the points are calculated according to the recursion formula and thrust force extremum principle and the critical slip surface can be obtained subsequently using the parameters. Lastly, the bearing capacity is calculated according to the critical slip surface. The comparison with other methods verifies its rationality. The results show that the three factors are similar to others and decrease with increasing of soil pressure. The method is a use of critical slip field method in the calculation of bearing capacity. It is easy to be understood and calculated and can provide some beneficial references for further research on bearing capacity for circular footing.
The bearing capacity of circular footing is studied using critical slip field method. The three factors under different earth pressures are presented in the form of tables and curves. Recursion formula is deduced according to the force equilibrium conditions of slice. Firstly, the soil in the calculation range that had been assumed previously can be divided into a series of slices and state points. Secondly, the parameters of all the points are calculated according to the recursion formula and thrust force extremum principle and the critical slip surface can be obtained subsequently using the parameters. Lastly, the bearing capacity is calculated according to the critical slip surface. The comparison with other methods verifies its rationality. The results show that the three factors are similar to others and decrease with increasing of soil pressure. The method is a use of critical slip field method in the calculation of bearing capacity. It is easy to be understood and calculated and can provide some beneficial references for further research on bearing capacity for circular footing.
2015, 23(5): 1013-1019.
As a modified material, the waste tire granulated rubber is expected to enhance the effectiveness of liner system in landfill. The existing results of compaction tests are in conflict to some extent since the compaction mechanism is complex. The compaction test of waste tire ground rubber and clay mixtures is conducted and the effect of rubber properties on compaction performance is studied. When the rubber mixing content increases from 0% to 25%,the optimum water content of the Kaolin mixture increases and that of the red clay mixtures decreases. The change of optimum water content of the mixtures is within 2.4% and the maximum dry density decreases from 1.65gcm-3 to 1.40gcm-3.The 12-mesh and 30-mesh rubber used in the present study show no significant difference on the compaction performance. Under the two effects of rubber particle rebound and specific surface area change, the optimum water content can either decrease(for coarse rubber),be about the same, or increase(for fine rubber) with the increasing of rubber mixing content,.The change is closely related to the properties of the matrix soil. The control parameters of water content and dry density at the preliminary design are put forward, which can basically meet the water content and degree of compaction requirements of compacted clay liner in the specification. The hydraulic conductivity of the mixtures is below 1.010-7cms-1 and also meets the requirements.
As a modified material, the waste tire granulated rubber is expected to enhance the effectiveness of liner system in landfill. The existing results of compaction tests are in conflict to some extent since the compaction mechanism is complex. The compaction test of waste tire ground rubber and clay mixtures is conducted and the effect of rubber properties on compaction performance is studied. When the rubber mixing content increases from 0% to 25%,the optimum water content of the Kaolin mixture increases and that of the red clay mixtures decreases. The change of optimum water content of the mixtures is within 2.4% and the maximum dry density decreases from 1.65gcm-3 to 1.40gcm-3.The 12-mesh and 30-mesh rubber used in the present study show no significant difference on the compaction performance. Under the two effects of rubber particle rebound and specific surface area change, the optimum water content can either decrease(for coarse rubber),be about the same, or increase(for fine rubber) with the increasing of rubber mixing content,.The change is closely related to the properties of the matrix soil. The control parameters of water content and dry density at the preliminary design are put forward, which can basically meet the water content and degree of compaction requirements of compacted clay liner in the specification. The hydraulic conductivity of the mixtures is below 1.010-7cms-1 and also meets the requirements.
2015, 23(5): 1020-1029.
The Xi'an metro line 3 paralleling to the strike of f7ground fissure, pass through locally hanging wall of the f7ground fissure. Based on the maximum activity values forecasted by the level monitoring datum, the influence of dislocation of ground fissure on metro tunnel was researched which parallel to the f7ground fissure's strike, utilizing the numerical method. The dislocation of ground fissure occurs in characteristic loess soil strata which are compose of loess soil, paleosol and silty clay. By gradually changing the distance between the out layer of metro tunnel liner and the f7ground fissure, the deformation and stress of the metro tunnel liner was computed under six calculation conditions. The results show that the tunnel liner is safe and has safety margin to some extent when the distance is 30meters between the out layer of metro tunnel liner and the f7ground fissure.
The Xi'an metro line 3 paralleling to the strike of f7ground fissure, pass through locally hanging wall of the f7ground fissure. Based on the maximum activity values forecasted by the level monitoring datum, the influence of dislocation of ground fissure on metro tunnel was researched which parallel to the f7ground fissure's strike, utilizing the numerical method. The dislocation of ground fissure occurs in characteristic loess soil strata which are compose of loess soil, paleosol and silty clay. By gradually changing the distance between the out layer of metro tunnel liner and the f7ground fissure, the deformation and stress of the metro tunnel liner was computed under six calculation conditions. The results show that the tunnel liner is safe and has safety margin to some extent when the distance is 30meters between the out layer of metro tunnel liner and the f7ground fissure.
2015, 23(5): 1030-1037.
Ground settlement and uneven settlement control is an important part of the tank construction safety. This paper analyzes the settlement deformation characteristics of tanks foundation added gravel ring wall in detail. The settlement and uneven settlement differences are compared for storage tank foundations added with gravel ring wall or concrete ring wall along both ring and radial directions. The relationships between elastic modulus of gravel ring wall and foundation settlement rules are analyzed. The different reinforcement effects of rectangular concrete ring walls and trapezoidal gravel ring walls are compared. Engineering suggestions of gravel ring walls used to reinforce the tank foundation are given in the final. The research results can have a great significance to similar engineering projects.
Ground settlement and uneven settlement control is an important part of the tank construction safety. This paper analyzes the settlement deformation characteristics of tanks foundation added gravel ring wall in detail. The settlement and uneven settlement differences are compared for storage tank foundations added with gravel ring wall or concrete ring wall along both ring and radial directions. The relationships between elastic modulus of gravel ring wall and foundation settlement rules are analyzed. The different reinforcement effects of rectangular concrete ring walls and trapezoidal gravel ring walls are compared. Engineering suggestions of gravel ring walls used to reinforce the tank foundation are given in the final. The research results can have a great significance to similar engineering projects.
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