2007 Vol. 15, No. 6

论文
Combined with RS and MAPGIS, the geohazards of the southeast of Himalaya Mountains in Tibet are studied. The geohazards include landslide, rock fall, mudflow, ice lake, and checked-up lake. The landslide, rock fall and mudflow account for about 95.3% of the total geohazards. The patterns of the development of geohazards are discussed accordingly. The results indicate that the geohazards are not evenly distributed in the region. A majority of the landslides are developed in Longzi county and Lang County. A majority of the mudflows are developed in Milin county, Longzi county and Luozha county. A majority of the rock falls took place in Longzi county. Meanwhile, the study shows that the landslides have a close relationship with the strata, the slope and the land type. The Xiukang group, Ridang formation and Nianqingtanggula group are prone to slide strata. The slope angle between 16~30 is the slope angle prone to slide. and The shrubbery and grassland are the two land types prone to slide. The Niuru formation is the stratum prone to take place mudflow. The range of 16~30 is the slope angle prone to mudflow too. The icefall and permanent snow area are the place easy to take place mudflow. However, the rock fall mainly takes place in the Nieru formation and on the slopes with slope angle larger than 60o. These findings can be used as a basis for a spatial prediction of the geohazards in the region. Combined with RS and MAPGIS, the geohazards of the southeast of Himalaya Mountains in Tibet are studied. The geohazards include landslide, rock fall, mudflow, ice lake, and checked-up lake. The landslide, rock fall and mudflow account for about 95.3% of the total geohazards. The patterns of the development of geohazards are discussed accordingly. The results indicate that the geohazards are not evenly distributed in the region. A majority of the landslides are developed in Longzi county and Lang County. A majority of the mudflows are developed in Milin county, Longzi county and Luozha county. A majority of the rock falls took place in Longzi county. Meanwhile, the study shows that the landslides have a close relationship with the strata, the slope and the land type. The Xiukang group, Ridang formation and Nianqingtanggula group are prone to slide strata. The slope angle between 16~30 is the slope angle prone to slide. and The shrubbery and grassland are the two land types prone to slide. The Niuru formation is the stratum prone to take place mudflow. The range of 16~30 is the slope angle prone to mudflow too. The icefall and permanent snow area are the place easy to take place mudflow. However, the rock fall mainly takes place in the Nieru formation and on the slopes with slope angle larger than 60o. These findings can be used as a basis for a spatial prediction of the geohazards in the region.
The edge area of Qinghai-Tibet Platean in Southwestern of China is famous for its abundant water-power and will be an engineering construction center,. Because of complicated and intense intrinsic-extrinsic dynamical geology action, high and steep rock slopes are well developed in the area. These slopes show some distinguished characteristics. They are different from general rock slopes because of the special geological background. According to the data from field investigation, these slopes can be characterized as super height, high geostress and complicated deformation and failure evolution process. The deformation and stabilization of slopes decide whether a project is feasible, affect the time limit for a project and control the construction cost. This paper points out that the deep fractures are the result of the coupling of endorgenic and exogenic geological processes by unloading of river valley and releasing of high geostress. The slope structure, strong geostress, rock property and high steep topographical features provide material foundation for deep fractures. Finally, the paper studies how deep fractures affect human engineering construction, and analyzes how these fractures influence the leakage of reservoir and the stability of slope. The prestressed anchoring cavern and other mountain reinforcement methods can be used to tackle deep fractures. The edge area of Qinghai-Tibet Platean in Southwestern of China is famous for its abundant water-power and will be an engineering construction center,. Because of complicated and intense intrinsic-extrinsic dynamical geology action, high and steep rock slopes are well developed in the area. These slopes show some distinguished characteristics. They are different from general rock slopes because of the special geological background. According to the data from field investigation, these slopes can be characterized as super height, high geostress and complicated deformation and failure evolution process. The deformation and stabilization of slopes decide whether a project is feasible, affect the time limit for a project and control the construction cost. This paper points out that the deep fractures are the result of the coupling of endorgenic and exogenic geological processes by unloading of river valley and releasing of high geostress. The slope structure, strong geostress, rock property and high steep topographical features provide material foundation for deep fractures. Finally, the paper studies how deep fractures affect human engineering construction, and analyzes how these fractures influence the leakage of reservoir and the stability of slope. The prestressed anchoring cavern and other mountain reinforcement methods can be used to tackle deep fractures.
The Qinghai-Tibet railway has a length of 550 km crossing the permafrost area. Along the line the permafrost ground temperature, frozen ground type and the ecological environment have great differences which make engineering and construction in the permafrost area become difficlt and complicated. So, this paper proposes a frozen ground engineering complexity concept, builds the evaluate model of frozen ground engineering complexity, and uses the GIS platform to analysis and research the engineering complexity of the Tangguola Mountain Crossing along the Qinghai-Tibet railway. The result indicates that engineering complexity of the area where the Qinghai-Tibet railway crosses is smaller than where the Qinghai-Tibet highway crosses. This situation shows that the frozen ground engineering along the Qinghai-Tibet highway is more complicated than that along the railway. Under the effect of various factors, the stability problems of the Qinghai-Tibet highway are much more complicated than that of the Qinghai-Tibet railway. The Qinghai-Tibet railway has a length of 550 km crossing the permafrost area. Along the line the permafrost ground temperature, frozen ground type and the ecological environment have great differences which make engineering and construction in the permafrost area become difficlt and complicated. So, this paper proposes a frozen ground engineering complexity concept, builds the evaluate model of frozen ground engineering complexity, and uses the GIS platform to analysis and research the engineering complexity of the Tangguola Mountain Crossing along the Qinghai-Tibet railway. The result indicates that engineering complexity of the area where the Qinghai-Tibet railway crosses is smaller than where the Qinghai-Tibet highway crosses. This situation shows that the frozen ground engineering along the Qinghai-Tibet highway is more complicated than that along the railway. Under the effect of various factors, the stability problems of the Qinghai-Tibet highway are much more complicated than that of the Qinghai-Tibet railway.
This paper aims at quality and parameters of rock mass in the No. 3 zone of Jing-chuan Mines. Statistics and numerical value models are applied to analyze the characteristics of classification and mechanical parameters based on the data of eleven drillhole logs. At first, the logging data were statistically analyzed. Joint and fissures at different depths in each drillhole were then analyzed. The rock masses were classified. The data for the mechanical model were obtained. And then, the three-dimensional mechanical model was made up which could taken into account characteristics of the entile rock mass. The mechanical characteristics of the distribution and change of mine mass were described. Finally, some important conclusions were summarized. The findings in the paper can provide practice data for the design of mining and numerical simulation. This paper aims at quality and parameters of rock mass in the No. 3 zone of Jing-chuan Mines. Statistics and numerical value models are applied to analyze the characteristics of classification and mechanical parameters based on the data of eleven drillhole logs. At first, the logging data were statistically analyzed. Joint and fissures at different depths in each drillhole were then analyzed. The rock masses were classified. The data for the mechanical model were obtained. And then, the three-dimensional mechanical model was made up which could taken into account characteristics of the entile rock mass. The mechanical characteristics of the distribution and change of mine mass were described. Finally, some important conclusions were summarized. The findings in the paper can provide practice data for the design of mining and numerical simulation.
This paper examines permeability of porous media under different confining pressures. It uses unchangeable water pressure method. Large size soft rocks with low permeability have been systematically tested with a new equipment called high pressure permeability testing machine in laboratory. The penetration water pressure fluctuation scope is 0.01 MPa. The seepage exit water volume testing precision is 0.05 ml. According to a linear relationship of water volume and time, seepage quantity can be accurately calculated. The test results demonstrate that the permeability coefficient decreases with the increasing of confining pressure, and increase when unloading. The increasing rate during unloading is lower than that during loading. On the basis of the axial strain variation situation, it is found that the rock permeability change is mainly affected by the confining pressure during the coupling process of stress-seeping in rock samples at laboratory. The confining lateral pressure makes the porosity and seepage pipes to have compressive deformation. This paper examines permeability of porous media under different confining pressures. It uses unchangeable water pressure method. Large size soft rocks with low permeability have been systematically tested with a new equipment called high pressure permeability testing machine in laboratory. The penetration water pressure fluctuation scope is 0.01 MPa. The seepage exit water volume testing precision is 0.05 ml. According to a linear relationship of water volume and time, seepage quantity can be accurately calculated. The test results demonstrate that the permeability coefficient decreases with the increasing of confining pressure, and increase when unloading. The increasing rate during unloading is lower than that during loading. On the basis of the axial strain variation situation, it is found that the rock permeability change is mainly affected by the confining pressure during the coupling process of stress-seeping in rock samples at laboratory. The confining lateral pressure makes the porosity and seepage pipes to have compressive deformation.
This paper examines the elastic solution of stress and displacement around a circular opening on the condition that the lateral pressure coefficient equals 1 firstly. The paper further derives the analytic solution of elasto-plastic stress and displacement for the axisymmetric plane strain problem around a circular opening. In the derivation, the Hoek-Brown impirical criterion is used as the limiting equilibrium condition. This paper examines the elastic solution of stress and displacement around a circular opening on the condition that the lateral pressure coefficient equals 1 firstly. The paper further derives the analytic solution of elasto-plastic stress and displacement for the axisymmetric plane strain problem around a circular opening. In the derivation, the Hoek-Brown impirical criterion is used as the limiting equilibrium condition.
The loess high-slope on western end of Shui Lian Dong colliery is an old landslide debris back-wall. There is an old landslide debris depost in the slope bottom. Surface water can infiltrate into the slope through loess uprightness joints and cranny. The groundwater flow gradually causes the formation of water cavities in the upper slope region. The slope further has loess stratification, obliquity (from 5to 10) and paleosols place. Surface water infiltrate into paleosol and induce water cavity exit with the top water cavity transfixion. The paleosol ideally prevents water. The loess stratification leans to ravine. The slope is unstable and will fail under the action of precipitations. The loess high-slope on western end of Shui Lian Dong colliery is an old landslide debris back-wall. There is an old landslide debris depost in the slope bottom. Surface water can infiltrate into the slope through loess uprightness joints and cranny. The groundwater flow gradually causes the formation of water cavities in the upper slope region. The slope further has loess stratification, obliquity (from 5to 10) and paleosols place. Surface water infiltrate into paleosol and induce water cavity exit with the top water cavity transfixion. The paleosol ideally prevents water. The loess stratification leans to ravine. The slope is unstable and will fail under the action of precipitations.
The ultimate bearing capacity of a rigid strip footings resting on undrained two-layered clays Is estimated using an elastio-plastic finite element method. For a wide range of problem geometries, the results are obtained and presented with the terms of modified bearing capacity factor. The results are compared with those obtained from existing limit analysis, empirical and semi-empirical solutions, upper bound solutions, as well asfinite element analysis based on the upper and lower bound limit theorems. The comparisons show that the elasto-plastic displacement finite element method can give robust and accurate solutions to the true limit bearing capacity of clay profiles. And the solutions of the paper have a good agreement with the lower bound solutions. However the upper bound solutions can overestimate the bearing capacity of undrained two-layered clays in some instance. The classical empirical solutions can underestimate the collapse load. The ultimate bearing capacity of a rigid strip footings resting on undrained two-layered clays Is estimated using an elastio-plastic finite element method. For a wide range of problem geometries, the results are obtained and presented with the terms of modified bearing capacity factor. The results are compared with those obtained from existing limit analysis, empirical and semi-empirical solutions, upper bound solutions, as well asfinite element analysis based on the upper and lower bound limit theorems. The comparisons show that the elasto-plastic displacement finite element method can give robust and accurate solutions to the true limit bearing capacity of clay profiles. And the solutions of the paper have a good agreement with the lower bound solutions. However the upper bound solutions can overestimate the bearing capacity of undrained two-layered clays in some instance. The classical empirical solutions can underestimate the collapse load.
There are a great deal earthen heritage sites in the arid areas of northwest China. Based on the analyses of the deteriorations of the earthen sites in the arid area, the third grade classification system and definition about the deteriorations of earthen sites are established. The analyses are based on te the causes, the manifestation modalities, and the engendered mechanisms of the deterioratins. The deteriorations of the earthen sites were divided into the two major types: the nature breakage and the man breakage. The nature breakage had 5 secondary classifications, 14 tertiary classifications. it includes slice-peeling (the rain erosion-peeling, the wind erosion-peeling and the cranny-peeling), recess (the salt-recess, the wind-recess and the fluvial recess), cranny (the unloading cranny, the tectonic cranny, the deformation cranny and the building cranny),gulch (the cranny-gulch and runoff-gulch), life-form breakage (the animal breakage and the plant breakage). The man breakage has two types: the old breakage and the latter-day breakage. There are a great deal earthen heritage sites in the arid areas of northwest China. Based on the analyses of the deteriorations of the earthen sites in the arid area, the third grade classification system and definition about the deteriorations of earthen sites are established. The analyses are based on te the causes, the manifestation modalities, and the engendered mechanisms of the deterioratins. The deteriorations of the earthen sites were divided into the two major types: the nature breakage and the man breakage. The nature breakage had 5 secondary classifications, 14 tertiary classifications. it includes slice-peeling (the rain erosion-peeling, the wind erosion-peeling and the cranny-peeling), recess (the salt-recess, the wind-recess and the fluvial recess), cranny (the unloading cranny, the tectonic cranny, the deformation cranny and the building cranny),gulch (the cranny-gulch and runoff-gulch), life-form breakage (the animal breakage and the plant breakage). The man breakage has two types: the old breakage and the latter-day breakage.
A slope at a granite mine site is comprised mainly fill, silty clay, muck and mucky soil, medium coarse sand with mud, cliff clay, residual sandy clay. The soils are underlain with a granitic bedrock. The maximum height of the slope is 75 m and the height of the soil part above the alluvium is about 50 m. The strength reduction based finite element method is used to study the stability of the slope. The potential mode of slope failure and the safety factor of every sliding mass are obtained. The numerical results show that there are three sliding surfaces in the slope, two of them are shallow sliding surfaces and the third is a deep one. The stability factors of two shallow sliding surfaces are 1.13 to 1.17, which is at a critical state. The stability factor of the deep sliding surface is 1.29, which is at a relatively stable state. According to the analysis results, two advices are put forward: (1) reducing the loading by cutting down the slope; (2) installing anti-slide steps under the sliding. A slope at a granite mine site is comprised mainly fill, silty clay, muck and mucky soil, medium coarse sand with mud, cliff clay, residual sandy clay. The soils are underlain with a granitic bedrock. The maximum height of the slope is 75 m and the height of the soil part above the alluvium is about 50 m. The strength reduction based finite element method is used to study the stability of the slope. The potential mode of slope failure and the safety factor of every sliding mass are obtained. The numerical results show that there are three sliding surfaces in the slope, two of them are shallow sliding surfaces and the third is a deep one. The stability factors of two shallow sliding surfaces are 1.13 to 1.17, which is at a critical state. The stability factor of the deep sliding surface is 1.29, which is at a relatively stable state. According to the analysis results, two advices are put forward: (1) reducing the loading by cutting down the slope; (2) installing anti-slide steps under the sliding.
An elasto-plastic shear strength reduction FDM is used to analyze the stability of slope with multi-steps. The numerical results show that the shape and position of the slip surface are related to width of the steps. Moreover, the width of the steps affect the failure mode and safety factor significantly. Some conclusions are put forward. An elasto-plastic shear strength reduction FDM is used to analyze the stability of slope with multi-steps. The numerical results show that the shape and position of the slip surface are related to width of the steps. Moreover, the width of the steps affect the failure mode and safety factor significantly. Some conclusions are put forward.
In order to quickly and accurately classify surrounding rock and instruct the tunnel construction, and on the basis of comprehensive review of the surrounding rock classification methods in domestic and abord, the paper proposes a method for quickly classification of surrounding rocks during tunnel construction period. The method combines qualitative and quantitative evaluations and uses experts evaluation method to quickly obtain the appraisal result for observing, measuring and appraisaling the surrounding rocks in the scene of excavating tunnel face. It does not need complex experiments and computations. In order to comprehensively reflect the tunnel surrounding situation and accurately appraise the project nature, and take into consideration of the Q-system, the paper appraises the surrounding rock of Fuxi tunnel on the basis of the first hand survey data using both the quick classification method and the Q-system method. It provides the rational supporting parameters for the construction of Fuxi tunnel. In order to quickly and accurately classify surrounding rock and instruct the tunnel construction, and on the basis of comprehensive review of the surrounding rock classification methods in domestic and abord, the paper proposes a method for quickly classification of surrounding rocks during tunnel construction period. The method combines qualitative and quantitative evaluations and uses experts evaluation method to quickly obtain the appraisal result for observing, measuring and appraisaling the surrounding rocks in the scene of excavating tunnel face. It does not need complex experiments and computations. In order to comprehensively reflect the tunnel surrounding situation and accurately appraise the project nature, and take into consideration of the Q-system, the paper appraises the surrounding rock of Fuxi tunnel on the basis of the first hand survey data using both the quick classification method and the Q-system method. It provides the rational supporting parameters for the construction of Fuxi tunnel.
Reservoir water level change can change the seepage field in the bank slope of the reservoir, and further cause the instability and failure of the slope. The seepage field in the slope can be divided in saturated and unsaturated seepage fields. The paper presents the calculated results of the position change of the underground water level line and the corresponding seepage field parameters. The results show that the rising velocity of the underground water level line in the bedrock evidently lags that in the upper loose deposit. This difference is due to the difference of the permeability coefficients between upper loose deposit and the base rock. The variation magnitudes of the seepage parameters such as the volume content, the pressure head, the flow velocity and the hydraulic gradient in the bedrock are rather smaller than those in the upper loose deposit. It indicates that the influence of the reservoir water level rise on the upper loose deposit is much more evident. Reservoir water level change can change the seepage field in the bank slope of the reservoir, and further cause the instability and failure of the slope. The seepage field in the slope can be divided in saturated and unsaturated seepage fields. The paper presents the calculated results of the position change of the underground water level line and the corresponding seepage field parameters. The results show that the rising velocity of the underground water level line in the bedrock evidently lags that in the upper loose deposit. This difference is due to the difference of the permeability coefficients between upper loose deposit and the base rock. The variation magnitudes of the seepage parameters such as the volume content, the pressure head, the flow velocity and the hydraulic gradient in the bedrock are rather smaller than those in the upper loose deposit. It indicates that the influence of the reservoir water level rise on the upper loose deposit is much more evident.
This paper takes the Longjing reservoir dam as an example to analyze the seepage and stability of reservoir clay core dams. The finite element method is used to examine the seepage. The slope stability is examined with the Swedish circle method and the Bishop method at the clay core dam. On this basis, the paper evaluates the safety of the seepage and the slippage resistivity of the Longjing reservoir dam. This paper takes the Longjing reservoir dam as an example to analyze the seepage and stability of reservoir clay core dams. The finite element method is used to examine the seepage. The slope stability is examined with the Swedish circle method and the Bishop method at the clay core dam. On this basis, the paper evaluates the safety of the seepage and the slippage resistivity of the Longjing reservoir dam.
The stress-strain relationship of loess with different depth and water content of loess slope is studied with the reduced triaxial compress test of undisturbed loess and compared with the results of conventional triaxial compress test of undisturbed loess. It is pointed that the deformation and failure process of loess slope under excavation and unloading can be reasonably explained by the reduced triaxial compress test. The test results show that the surface unsaturated loess of loess slope with toe excavation is easy to appear strain softening or plastic flow, and strength reduction, the deep layer saturated loess appears strain softening under the condition of mid-lower confining pressure and strain hardening and strength increase under high confining pressure. Then, based on the results of reduced triaxial compress test, deformation mechanism analysis of loess cut slope is made. It is considered that the particular engineering geological conditions of loess slope leads to a disadvantageous combination of water content and confining pressure to the strength of soil. Then the disadvantageous combination causes deformation and failure of soil mass and slope. The deformation and failure mechanism of loess slope under excavation belongs to creeping slide and crack arising from pressing or retrogressive slide. The stress-strain relationship of loess with different depth and water content of loess slope is studied with the reduced triaxial compress test of undisturbed loess and compared with the results of conventional triaxial compress test of undisturbed loess. It is pointed that the deformation and failure process of loess slope under excavation and unloading can be reasonably explained by the reduced triaxial compress test. The test results show that the surface unsaturated loess of loess slope with toe excavation is easy to appear strain softening or plastic flow, and strength reduction, the deep layer saturated loess appears strain softening under the condition of mid-lower confining pressure and strain hardening and strength increase under high confining pressure. Then, based on the results of reduced triaxial compress test, deformation mechanism analysis of loess cut slope is made. It is considered that the particular engineering geological conditions of loess slope leads to a disadvantageous combination of water content and confining pressure to the strength of soil. Then the disadvantageous combination causes deformation and failure of soil mass and slope. The deformation and failure mechanism of loess slope under excavation belongs to creeping slide and crack arising from pressing or retrogressive slide.
The quality of compaction is crucial to high-filling. Dynamic compaction is a most widely used method for ground treatment. In the paper, experimental test for broken stone treatment by dynamic compaction is studied. Firstly, the properties of the filling of broken stones are analyzed. Secondly, the dynamic compaction test, the dry density test, and the particle-size distribution test are tried out. Thus, the reasonable working parameters and working techniques are defined. Lastly, based on the load-settlement test, the result of the stabilization is well acquired in according with work parameters. The quality of compaction is crucial to high-filling. Dynamic compaction is a most widely used method for ground treatment. In the paper, experimental test for broken stone treatment by dynamic compaction is studied. Firstly, the properties of the filling of broken stones are analyzed. Secondly, the dynamic compaction test, the dry density test, and the particle-size distribution test are tried out. Thus, the reasonable working parameters and working techniques are defined. Lastly, based on the load-settlement test, the result of the stabilization is well acquired in according with work parameters.
This paper analyzes the tailing material of Mijiangou dam and their composion, structural, physical and mechanical characteristics. Tailing material parameters of dynamic characteristics are made certain through vibrational triaxial texts of dynamic characteristics. Index models of dynamic characteristics are studied. It obtains the changing laws of dynamic stress, dynamic modulus, damp ratio, dynamic shear modulus along with dynamic strain, and dynamic stress and destruct vibration, vibration times-pore pressure ratio changing laws. It puts forward a pore pressure model that accords to experimentation results. Then it gets some fruits and conclusions. The results offer a scientific basis and technical guidance for quake-power analysing and aseismatic stability estimation. This paper analyzes the tailing material of Mijiangou dam and their composion, structural, physical and mechanical characteristics. Tailing material parameters of dynamic characteristics are made certain through vibrational triaxial texts of dynamic characteristics. Index models of dynamic characteristics are studied. It obtains the changing laws of dynamic stress, dynamic modulus, damp ratio, dynamic shear modulus along with dynamic strain, and dynamic stress and destruct vibration, vibration times-pore pressure ratio changing laws. It puts forward a pore pressure model that accords to experimentation results. Then it gets some fruits and conclusions. The results offer a scientific basis and technical guidance for quake-power analysing and aseismatic stability estimation.
The deformation characteristic of hydraulic fill in Shanghai is studied in this paper. The roadbed made of hydraulic fill can be deformed liquefied under the traveling traffic loading. The same dynamic stress, different dynamic frequency are adopted to simulate the traveling traffic loading. Hydraulic fill is tested by dynamic triaxial experiment. Through the analysis of these test results, the following conclusions are drawn. With the same consolidation ratio swing, axial strain increases linearly with increasing vibration times. the axial strain increases slowly in the start of increasing pore water pressure. When pore water pressure ratio reaches the certain value,the axial strain increases quickly up to destroy. The relation between the axial strain and the radial strain and the shear strain is linear. Results of tests supply valuable reference to design, construction of roadbed and avoid disaster of engineering geological in hydraulic fill of Shanghai. The deformation characteristic of hydraulic fill in Shanghai is studied in this paper. The roadbed made of hydraulic fill can be deformed liquefied under the traveling traffic loading. The same dynamic stress, different dynamic frequency are adopted to simulate the traveling traffic loading. Hydraulic fill is tested by dynamic triaxial experiment. Through the analysis of these test results, the following conclusions are drawn. With the same consolidation ratio swing, axial strain increases linearly with increasing vibration times. the axial strain increases slowly in the start of increasing pore water pressure. When pore water pressure ratio reaches the certain value,the axial strain increases quickly up to destroy. The relation between the axial strain and the radial strain and the shear strain is linear. Results of tests supply valuable reference to design, construction of roadbed and avoid disaster of engineering geological in hydraulic fill of Shanghai.
Xian is one of the most serious areas of land subsidence and land fissure geology disaster in our country. I In order to monitor land subsidence and land fissure in Xian, a GPS reference network was established. The paper includes the fundamental of GPS reference network, observation outside and data processing, and recounts some key technology. It is verified by practical example in this paper that the height measuring precision was achieved when the urban land subsidence was monitored using GPS surveying. The precision of GPS surveying can satisfy the requirement of the urban land subsidence and land fissure. Result of monitoring has a good coherence with precise leveling. Xian is one of the most serious areas of land subsidence and land fissure geology disaster in our country. I In order to monitor land subsidence and land fissure in Xian, a GPS reference network was established. The paper includes the fundamental of GPS reference network, observation outside and data processing, and recounts some key technology. It is verified by practical example in this paper that the height measuring precision was achieved when the urban land subsidence was monitored using GPS surveying. The precision of GPS surveying can satisfy the requirement of the urban land subsidence and land fissure. Result of monitoring has a good coherence with precise leveling.
There are many methods in detection of grouting quality in mine cavities. However, there are no mature and credibility technical methods. This paper introduces a method combining DC sounding and Electromagnetic CT techniques. The two techniques operate simply and could reflect the grouting quality of cavities in detail. The combined method has applied to the detection of grouting quality in mine cavities along a railway The results indicate that the grouting quality is well at the segment K0+278~K0+45. The results of the two techniques are consistency. It is proved that the combined method is reasonable and feasible for detecting the grouting quality at mine cavities. The case study in this paper can provide experience for testing other homogeneous reinforce effect. There are many methods in detection of grouting quality in mine cavities. However, there are no mature and credibility technical methods. This paper introduces a method combining DC sounding and Electromagnetic CT techniques. The two techniques operate simply and could reflect the grouting quality of cavities in detail. The combined method has applied to the detection of grouting quality in mine cavities along a railway The results indicate that the grouting quality is well at the segment K0+278~K0+45. The results of the two techniques are consistency. It is proved that the combined method is reasonable and feasible for detecting the grouting quality at mine cavities. The case study in this paper can provide experience for testing other homogeneous reinforce effect.
The seismic hazard of sites must be evaluated and aseismatic design must be adopted for structures before projects are constructed. It is difficult for engineers to choose the appropriate acceleration of earthquake-resistance for projects safely and economically in actual application. This is because only a scope of acceleration of earthquake-resistance or earthquake intensity is provided for a region by relevant departments in China. Additionally, the range of acceleration corresponding to an earthquake intensity is very large. In order to solve the problem, a seismic hazard assessment system is developed based on the probability seismic hazard assessment theory. The acceleration of earthquake-resistance for projects can be calculated conveniently and quickly using the assessment system developed according to correlative earthquake activity parameters. Consequently, the problem of choosing the acceleration of earthquake-resistance safely and economically can be solved well. In this paper, an accurate solving algorithm and an approximate solving algorithm are given respectively toward the problems of a line-source and an area-source. The two sources have difficulties to be handled in programming. Some assessment calculations are given with examples. The calculation results are consistent with these data promulgated by China Earthquake Administration (CEA). Therefore, the reliability of the system developed in this paper is proved to be good to some extent. The seismic hazard of sites must be evaluated and aseismatic design must be adopted for structures before projects are constructed. It is difficult for engineers to choose the appropriate acceleration of earthquake-resistance for projects safely and economically in actual application. This is because only a scope of acceleration of earthquake-resistance or earthquake intensity is provided for a region by relevant departments in China. Additionally, the range of acceleration corresponding to an earthquake intensity is very large. In order to solve the problem, a seismic hazard assessment system is developed based on the probability seismic hazard assessment theory. The acceleration of earthquake-resistance for projects can be calculated conveniently and quickly using the assessment system developed according to correlative earthquake activity parameters. Consequently, the problem of choosing the acceleration of earthquake-resistance safely and economically can be solved well. In this paper, an accurate solving algorithm and an approximate solving algorithm are given respectively toward the problems of a line-source and an area-source. The two sources have difficulties to be handled in programming. Some assessment calculations are given with examples. The calculation results are consistent with these data promulgated by China Earthquake Administration (CEA). Therefore, the reliability of the system developed in this paper is proved to be good to some extent.
There are many factors controlling karst development. Some of the factors are unascertain. On the base of analyzing a lot of existing information, such as Qiyueshan tunnel, Baziling tunnel, Yesanguan tunnel, Maluqing tunnel in Yiwan railway and Yuanliangshan tunnel in Yuhuai railway, geological guide lines system of prediction karst hazard in the course of tunnel construction is brought forward. These guide lines contain stratum and rock character, geology structure, landform and physiognomy, surface water and groundwater, tunnel design. According to actual date, karst hazard fatalness is divided into high, middle and low levels. Engineering geology characters of these three levels are made sure. Calculating powers of each individual factor are studied by using an expert evaluating method. The knowledge storeroom of karst geological prediction expert system is designed. The expert system of karst geological prediction in mountain tunnel is studied. Through application in Yiwan railway tunnel construction, the reliability of this expert system has been analyzed. There are many factors controlling karst development. Some of the factors are unascertain. On the base of analyzing a lot of existing information, such as Qiyueshan tunnel, Baziling tunnel, Yesanguan tunnel, Maluqing tunnel in Yiwan railway and Yuanliangshan tunnel in Yuhuai railway, geological guide lines system of prediction karst hazard in the course of tunnel construction is brought forward. These guide lines contain stratum and rock character, geology structure, landform and physiognomy, surface water and groundwater, tunnel design. According to actual date, karst hazard fatalness is divided into high, middle and low levels. Engineering geology characters of these three levels are made sure. Calculating powers of each individual factor are studied by using an expert evaluating method. The knowledge storeroom of karst geological prediction expert system is designed. The expert system of karst geological prediction in mountain tunnel is studied. Through application in Yiwan railway tunnel construction, the reliability of this expert system has been analyzed.
2007, 15(6): 855-856.
Abstract(2721)