Online Submission
Manuscript Tracking
Peer Review
Editor Work2010 Vol. 18, No. 3
Previous Issue
2010, 18(3): 289-296.
Abstract
8144KB
The Yushu Ms 7.1 earthquake was happened at 7： 49 on April 14, 2010 in Yushu county of Qinghai province. Besides continuous surface rupture and a large number of properties collapse,the types of geohazards induced by earthquake include rock fall,landslide,potential debris flow,etc. In addition,the geohazards can be aggravated by the earthquakeinduced sandy soil liquefaction,as well as burst of a channel,in local areas. Based on field investigation and comparison of the geohazard data before and after the Yushu earthquake,the authors summarize the major characteristics of the Yushu Ms7.1 earthquake,such as the amount of geohazard increasing obviously after the earthquake,the distribution of geohazards controlled by the active faults,the lowposition soil/colluvial landslides predominant,the effect of geohazard chain being notable,etc. some proposals for geohazard control during reconstruction have been given forth in this paper．
The Yushu Ms 7.1 earthquake was happened at 7： 49 on April 14, 2010 in Yushu county of Qinghai province. Besides continuous surface rupture and a large number of properties collapse,the types of geohazards induced by earthquake include rock fall,landslide,potential debris flow,etc. In addition,the geohazards can be aggravated by the earthquakeinduced sandy soil liquefaction,as well as burst of a channel,in local areas. Based on field investigation and comparison of the geohazard data before and after the Yushu earthquake,the authors summarize the major characteristics of the Yushu Ms7.1 earthquake,such as the amount of geohazard increasing obviously after the earthquake,the distribution of geohazards controlled by the active faults,the lowposition soil/colluvial landslides predominant,the effect of geohazard chain being notable,etc. some proposals for geohazard control during reconstruction have been given forth in this paper．
2010, 18(3): 297-304.
The Jiweishan event happened at June 5, 2009 in Wulong county of Chongqing municipality of China. It is a mega sliding rockfall(volume is larger than 100104m3),and an oversize geological disaster(the number of missing and death is greater than 30 in Chinese rule). It is a basic condition in substance and structure that Jiweishan rockmass is of layered limestone,weak interlayers and fissures approximately in SN and EW direction. Raining seepage and karstification in a long period may decrease strength of weak layers in the bottom of the rockmass and enlarge fissures in the mountaintop,so that layered rockmass is pulled out easily. Based analogical analysis,Jiweishan dangerous rockmass may be result from pull cracks in the mountaintop produced by cantilever plate effect which derives from great iron ore mined out area under mountain. It is obtained from the sliding force analysis in apparent direction that outward apparent sliding force makes rockmass in crawling into rockfall gradually by through to overcome a friction force from its bottom and a resistant shearing force on its front end. The Jiweishan rockfall disaster is induced by iron ore mined out area and the apparent direction sliding force together. It is a process in chain reaction that consists of rockmass cracks～creep sliding along weak layer～bursting rockfall～debris impact～come into being disaster. The dynamical source of the event is explained for emergency management decision and a simple method in technical support for similar problems is put forward in this paper.
The Jiweishan event happened at June 5, 2009 in Wulong county of Chongqing municipality of China. It is a mega sliding rockfall(volume is larger than 100104m3),and an oversize geological disaster(the number of missing and death is greater than 30 in Chinese rule). It is a basic condition in substance and structure that Jiweishan rockmass is of layered limestone,weak interlayers and fissures approximately in SN and EW direction. Raining seepage and karstification in a long period may decrease strength of weak layers in the bottom of the rockmass and enlarge fissures in the mountaintop,so that layered rockmass is pulled out easily. Based analogical analysis,Jiweishan dangerous rockmass may be result from pull cracks in the mountaintop produced by cantilever plate effect which derives from great iron ore mined out area under mountain. It is obtained from the sliding force analysis in apparent direction that outward apparent sliding force makes rockmass in crawling into rockfall gradually by through to overcome a friction force from its bottom and a resistant shearing force on its front end. The Jiweishan rockfall disaster is induced by iron ore mined out area and the apparent direction sliding force together. It is a process in chain reaction that consists of rockmass cracks～creep sliding along weak layer～bursting rockfall～debris impact～come into being disaster. The dynamical source of the event is explained for emergency management decision and a simple method in technical support for similar problems is put forward in this paper.
2010, 18(3): 305-311.
Earthquake is one of the main factors to affect the stability of slopes or landslides．The huge landslide on Bailongjiang was formed in toppling deformation of the bedding slope. It was in a stable state under natural conditions. After the 5.12 Wenchuan Earthquake,the huge landslide appeared moving phenomena including continuous linking crack and dislocation steps in the trailing edge of landslide. Especially,the rupture deformation of the landslide downstream area tended to be evident.This paper examines the recurrence mechanism of the huge landslide under the earthquake. It is based on the regional geological conditions of landslide. It investigates the basic features in detail and the recurrence phenomenon and the characteristics of landslide. It is accomplished a dynamic analysis of landslide recurrence with the software builtin module FLAC3D. The numerical simulation and analysis show thatthe deformation and damage of the landslide is affected deeply by terrain under earthquake loading. The landslide has an obvious amplification effect under the action of the seismic waves. Compared with the steady rock slope adjacent to the landslide,the landslide was more sensitive to the earthquake loading under the same earthquake magnitude. This result explains well the causes of recurrence of landslide under the 5.12 Wenchuan Earthquake．
Earthquake is one of the main factors to affect the stability of slopes or landslides．The huge landslide on Bailongjiang was formed in toppling deformation of the bedding slope. It was in a stable state under natural conditions. After the 5.12 Wenchuan Earthquake,the huge landslide appeared moving phenomena including continuous linking crack and dislocation steps in the trailing edge of landslide. Especially,the rupture deformation of the landslide downstream area tended to be evident.This paper examines the recurrence mechanism of the huge landslide under the earthquake. It is based on the regional geological conditions of landslide. It investigates the basic features in detail and the recurrence phenomenon and the characteristics of landslide. It is accomplished a dynamic analysis of landslide recurrence with the software builtin module FLAC3D. The numerical simulation and analysis show thatthe deformation and damage of the landslide is affected deeply by terrain under earthquake loading. The landslide has an obvious amplification effect under the action of the seismic waves. Compared with the steady rock slope adjacent to the landslide,the landslide was more sensitive to the earthquake loading under the same earthquake magnitude. This result explains well the causes of recurrence of landslide under the 5.12 Wenchuan Earthquake．
2010, 18(3): 312-319.
The Wenchuan earthquake occurred along the Longmenshan thrust fault belt. The Longmenshan central fault is the earthquake causing fault. The total rupture length along the Longmenshan central fault caused by the Wenchuan earthquake is about 270 km and the average vertical and horizontal displacement range from 1.0 m to 5.0 m,up to about 9.8 m in local parts. A lot of buildings were broken in the area where the ruptures passed through. In this paper,the authors report the investigation results of the vertical and horizontal displacements,as well as the width of rupture influenced zones which were confirmed by the geophysical survey methods,in different locations along the Longmenshan central fault. It is indicated that the influenced scopes of the earthquake ruptures mainly range from16 m to 60 m,and the relationship between the influenced scopes(D)and the vertical displacement(H)is obvious linearity,which can be expressed as: D=10.11H+16.0. Due to the Longmenshan central fault being a mainly thrusting fault,the influenced zone ratio between the hanging wall side and the foot wall side is generally from 3：1 to 2：1,which can help to determinate the safe distance for building site. On the basis of field investigation and using overseas experience for reference,the limit of the safe distance on the hanging wall side should be not less than 15 m,and that on the foot wall side should be not less than 10 m. This research work has important significance for safe site selection in Longmenshan region during reconstruction after the earthquake．
The Wenchuan earthquake occurred along the Longmenshan thrust fault belt. The Longmenshan central fault is the earthquake causing fault. The total rupture length along the Longmenshan central fault caused by the Wenchuan earthquake is about 270 km and the average vertical and horizontal displacement range from 1.0 m to 5.0 m,up to about 9.8 m in local parts. A lot of buildings were broken in the area where the ruptures passed through. In this paper,the authors report the investigation results of the vertical and horizontal displacements,as well as the width of rupture influenced zones which were confirmed by the geophysical survey methods,in different locations along the Longmenshan central fault. It is indicated that the influenced scopes of the earthquake ruptures mainly range from16 m to 60 m,and the relationship between the influenced scopes(D)and the vertical displacement(H)is obvious linearity,which can be expressed as: D=10.11H+16.0. Due to the Longmenshan central fault being a mainly thrusting fault,the influenced zone ratio between the hanging wall side and the foot wall side is generally from 3：1 to 2：1,which can help to determinate the safe distance for building site. On the basis of field investigation and using overseas experience for reference,the limit of the safe distance on the hanging wall side should be not less than 15 m,and that on the foot wall side should be not less than 10 m. This research work has important significance for safe site selection in Longmenshan region during reconstruction after the earthquake．
2010, 18(3): 320-319.
Cut slopes are usually formed during excavating in rock mass. The rock structural surfaces are exposed and rock blocks are formed. They influence the cut slope and cause it breaking. The failure would occur after the original static equilibrium state is destroyed and the stress is redistributed. Therefore,the stability of rock blocks formed with structural surfaces is the important factor that determines the stability of rock slope. This paper establishes a 3D solid model to realize the visible operation of cut slope and structural planes and excavation terrain model on an AutoCAD Platform. It then makes sectional cutting of twodimensional graphs in different locations. It further makes a forecast and analysis of structural surface assembly blocks possibly existed after excavation. It adopts the block computational procedure(Swedge)to verify the key block and makes an evaluation on its stability. The results show that its easily to search the key block of rock slope through 3D solid model and the slice technology in combination with block calculation. It is proved that this method is simple. The calculation result is accurate. The search method is feasible．
Cut slopes are usually formed during excavating in rock mass. The rock structural surfaces are exposed and rock blocks are formed. They influence the cut slope and cause it breaking. The failure would occur after the original static equilibrium state is destroyed and the stress is redistributed. Therefore,the stability of rock blocks formed with structural surfaces is the important factor that determines the stability of rock slope. This paper establishes a 3D solid model to realize the visible operation of cut slope and structural planes and excavation terrain model on an AutoCAD Platform. It then makes sectional cutting of twodimensional graphs in different locations. It further makes a forecast and analysis of structural surface assembly blocks possibly existed after excavation. It adopts the block computational procedure(Swedge)to verify the key block and makes an evaluation on its stability. The results show that its easily to search the key block of rock slope through 3D solid model and the slice technology in combination with block calculation. It is proved that this method is simple. The calculation result is accurate. The search method is feasible．
2010, 18(3): 325-332.
Brillouin Optical TimeDomain Reflectometer(BOTDR)is a newly developed distributed fiber optic sensing technique. It has some unique functions such as distributed,long distance,antielectromagnetic interference,and waterproof. It is very suitable and useful to the monitoring and earlywarning of geological engineering such as slope engineering. However,poor strain coordination,fragility and difficulty for abnormal strain location are some of the problems for this technique to be applied to soil slope. In this paper,the BOTDR was applied to monitor the deformation of a small scale slope model built in laboratory. The fiber was attached to geotextile and geogrid. The two materials are very popular in slope treatment. They were emplaced in the fill slope at different depths while the slope model was being built. Microstrain of the slope deformation at varied loads were obtained with the BOTDR. By data processing and analysis,the abnormal deformation can be distinguished and its position can also be identified．
Brillouin Optical TimeDomain Reflectometer(BOTDR)is a newly developed distributed fiber optic sensing technique. It has some unique functions such as distributed,long distance,antielectromagnetic interference,and waterproof. It is very suitable and useful to the monitoring and earlywarning of geological engineering such as slope engineering. However,poor strain coordination,fragility and difficulty for abnormal strain location are some of the problems for this technique to be applied to soil slope. In this paper,the BOTDR was applied to monitor the deformation of a small scale slope model built in laboratory. The fiber was attached to geotextile and geogrid. The two materials are very popular in slope treatment. They were emplaced in the fill slope at different depths while the slope model was being built. Microstrain of the slope deformation at varied loads were obtained with the BOTDR. By data processing and analysis,the abnormal deformation can be distinguished and its position can also be identified．
2010, 18(3): 333-339.
The high manmade slope is at the Antaibao coal mine，where underground tunnel mining and ground openpit mining are carried out at the same time. The distribution regularities of the composite stress and displacement field in the slope are analyzed by taking into account the effect of the tunnel mining direction with respect to the above openpit slope.Three tunnel mining excavation directions(ie,toward,parallel and opposite to the above openpit slope) are examined. The research results indicate that the underground mine is advanced to the stability of slope. However,the excavation direction has some effect to the slope stability. When mining from the opposite direction,the two types of different displacements are represented as the advance of working face. The topping failure is the main form of slope failure in the prophase of mining. The stability of slope is increased in the anaphase. When mining from the toward direction,the width of coal wedge reduces continuously. The slumping shear slide is generated possible. When mining from the parallel direction under the slope,the stretching failure is also generated possible. At the end,the some suggestions are given on the deformation mechanism of slope under the combined mining．
The high manmade slope is at the Antaibao coal mine，where underground tunnel mining and ground openpit mining are carried out at the same time. The distribution regularities of the composite stress and displacement field in the slope are analyzed by taking into account the effect of the tunnel mining direction with respect to the above openpit slope.Three tunnel mining excavation directions(ie,toward,parallel and opposite to the above openpit slope) are examined. The research results indicate that the underground mine is advanced to the stability of slope. However,the excavation direction has some effect to the slope stability. When mining from the opposite direction,the two types of different displacements are represented as the advance of working face. The topping failure is the main form of slope failure in the prophase of mining. The stability of slope is increased in the anaphase. When mining from the toward direction,the width of coal wedge reduces continuously. The slumping shear slide is generated possible. When mining from the parallel direction under the slope,the stretching failure is also generated possible. At the end,the some suggestions are given on the deformation mechanism of slope under the combined mining．
2010, 18(3): 340-344.
The red mud of Bayer's method has a very special mineral compositions and poor mechanical properties, It's the first time to use Bayer's drytype storage of red mud in the yard at home by Ping-guo aluminum company. The properties of red mud has been examined by the experimental tests including particle size distribution, mineral compositions, chemical compositions, physical and mechanical properties. It's concluded that the Bayer's red mud with high Fe2O3 content, small particle size and belongs to poor grading soil; Based on the operation characteristics of red mud yard, Its points out that the problems of drainage system as well as the consolidation of the red mud, the studies shows that the later stage of red mud yard may be immersed in the water with a long time due to the slow drainage, and thus it would be has some effect on the stability of red mud yard.
The red mud of Bayer's method has a very special mineral compositions and poor mechanical properties, It's the first time to use Bayer's drytype storage of red mud in the yard at home by Ping-guo aluminum company. The properties of red mud has been examined by the experimental tests including particle size distribution, mineral compositions, chemical compositions, physical and mechanical properties. It's concluded that the Bayer's red mud with high Fe2O3 content, small particle size and belongs to poor grading soil; Based on the operation characteristics of red mud yard, Its points out that the problems of drainage system as well as the consolidation of the red mud, the studies shows that the later stage of red mud yard may be immersed in the water with a long time due to the slow drainage, and thus it would be has some effect on the stability of red mud yard.
2010, 18(3): 345-350.
GIS and numerical simulation techniques are used to quantitative risk assessment of induced earthquake in the ThreeGorge reservoir head area. The technical route is that the simulation model is set up through the analysis of affecting factors. The simulation result is obtained with FLAC 3D. The assessment database is set up by the result of simulation and monitoring data. Each unit is estimated with the maximum tensile strain criterion for judging rock tensile failure and the MohrCoulomb criterion for judging rock shear failure. The unit is further estimated by comparing the first principal stress,the third principal stress and the displacement where the induced earthquake had taken place after impounding of the reservoir on a GIS platform. The result shows that building database containing various data based on the same GIS platform is the basement of integrated factor model. The result of risk assessment possesses the reliability in the ThreeGorges reservoir head area. The simulation result is also calculated with the earthquake model and the calculated result is further modified with the monitored data．
GIS and numerical simulation techniques are used to quantitative risk assessment of induced earthquake in the ThreeGorge reservoir head area. The technical route is that the simulation model is set up through the analysis of affecting factors. The simulation result is obtained with FLAC 3D. The assessment database is set up by the result of simulation and monitoring data. Each unit is estimated with the maximum tensile strain criterion for judging rock tensile failure and the MohrCoulomb criterion for judging rock shear failure. The unit is further estimated by comparing the first principal stress,the third principal stress and the displacement where the induced earthquake had taken place after impounding of the reservoir on a GIS platform. The result shows that building database containing various data based on the same GIS platform is the basement of integrated factor model. The result of risk assessment possesses the reliability in the ThreeGorges reservoir head area. The simulation result is also calculated with the earthquake model and the calculated result is further modified with the monitored data．
2010, 18(3): 351-356.
Due to many reasons such as the global warming,urban heat island effect and the geological concerns of nuclear waste disposal,temperature effects on the engineering properties of the clayey soils have being paid more and more attention. This paper uses the falling head permeability test to measure the permeability of clayey soils directly at various temperatures from 5 to 45℃. The soil samples are made from Nanjing Xiashu soil and silt clay. The results show that the temperature has significant impact on the permeability of the soil specimens. Firstly,the permeability increases upon heating; secondly,as the dry density of the clayey soil increases,the variation of permeability with temperature decreases correspondingly； thirdly,the mixed soil shows greater permeability than either silt clay or Nanjing Xiashu soil,and the silt clays permeability is a bit higher than that of Nanjing Xiashu soil within the experimental temperature range from 5 to 45℃. Finally,the mechanism of temperature effects on the permeability of clayey soils is discussed in terms of the viscosity of water,the double layer and micromeso structure change with temperature.
Due to many reasons such as the global warming,urban heat island effect and the geological concerns of nuclear waste disposal,temperature effects on the engineering properties of the clayey soils have being paid more and more attention. This paper uses the falling head permeability test to measure the permeability of clayey soils directly at various temperatures from 5 to 45℃. The soil samples are made from Nanjing Xiashu soil and silt clay. The results show that the temperature has significant impact on the permeability of the soil specimens. Firstly,the permeability increases upon heating; secondly,as the dry density of the clayey soil increases,the variation of permeability with temperature decreases correspondingly； thirdly,the mixed soil shows greater permeability than either silt clay or Nanjing Xiashu soil,and the silt clays permeability is a bit higher than that of Nanjing Xiashu soil within the experimental temperature range from 5 to 45℃. Finally,the mechanism of temperature effects on the permeability of clayey soils is discussed in terms of the viscosity of water,the double layer and micromeso structure change with temperature.
2010, 18(3): 357-362.
Bentonite is attracting a greater attention as buffer and backfill material of the engineering barrier for geological disposal of highlevel radioactive nuclear waste,because it can offer impermeability and swelling properties. But the pure compacted bentonite strength decreases with increasing hydration,which will reduce the buffer capability in the practice engineering. To solve this problem,sand is often used to form compacted sandbentomite mixtures(SBMs)to provide high thermal conductivity,excellent compaction capacity,longtime stability,and low engineering cost. The factors affecting the hydraulic conductivity of SBMs are studied in this paper. They include bentonite content,grain size distribution,moisture content,dry density,compacting method and energy,and bentonite type. The studies show that the hydraulic conductivity of SBMs is controlled by the hydraulic conductivity of the bentonite. It also decreases as dry density and bentonite content increase. But when the bentonite content reaches a critical point,the influence of increasing bentonite to decrease the hydraulic conductivity is limited. A fine and wellgraded SBM is likely to have a lower hydraulic conductivity than a coarse and poorly graded material. The internal erosion or erodibility based on the grain size distribution of the SBMs has a negative effect on the final hydraulic conductivity. The lowest hydraulic conductivity is gained when the mixtures are compacted close to optimum moisture content. Also,the mixtures compacted at moisture contents slightly above optimum values give lower hydraulic conductivity than when compacted at slightly under the optimum moisture content．
Bentonite is attracting a greater attention as buffer and backfill material of the engineering barrier for geological disposal of highlevel radioactive nuclear waste,because it can offer impermeability and swelling properties. But the pure compacted bentonite strength decreases with increasing hydration,which will reduce the buffer capability in the practice engineering. To solve this problem,sand is often used to form compacted sandbentomite mixtures(SBMs)to provide high thermal conductivity,excellent compaction capacity,longtime stability,and low engineering cost. The factors affecting the hydraulic conductivity of SBMs are studied in this paper. They include bentonite content,grain size distribution,moisture content,dry density,compacting method and energy,and bentonite type. The studies show that the hydraulic conductivity of SBMs is controlled by the hydraulic conductivity of the bentonite. It also decreases as dry density and bentonite content increase. But when the bentonite content reaches a critical point,the influence of increasing bentonite to decrease the hydraulic conductivity is limited. A fine and wellgraded SBM is likely to have a lower hydraulic conductivity than a coarse and poorly graded material. The internal erosion or erodibility based on the grain size distribution of the SBMs has a negative effect on the final hydraulic conductivity. The lowest hydraulic conductivity is gained when the mixtures are compacted close to optimum moisture content. Also,the mixtures compacted at moisture contents slightly above optimum values give lower hydraulic conductivity than when compacted at slightly under the optimum moisture content．
2010, 18(3): 363-370.
Anthrosols are a group of soils that have been heavily modified due to human activities. This paper studies systematically the anthrosols for understanding their engineering property and application. The connotations of anthrosols are defined,and their origins are analyzed. The classification principle of anthrosols is proposed,and an engineering classification and application system of anthrosols is established. Based on their origins,the anthrosols are classified into two types,five subtypes and eleven categories. Their connotation,basic principle,engineering property and disadvantage are introduced in detail. Finally the engineering utilization and application scope of each category of anthrosols is presented. These research results provide a theoretical basis for further study and application of anthrosols．
Anthrosols are a group of soils that have been heavily modified due to human activities. This paper studies systematically the anthrosols for understanding their engineering property and application. The connotations of anthrosols are defined,and their origins are analyzed. The classification principle of anthrosols is proposed,and an engineering classification and application system of anthrosols is established. Based on their origins,the anthrosols are classified into two types,five subtypes and eleven categories. Their connotation,basic principle,engineering property and disadvantage are introduced in detail. Finally the engineering utilization and application scope of each category of anthrosols is presented. These research results provide a theoretical basis for further study and application of anthrosols．
2010, 18(3): 371-375.
Soil specimens were moulded according to different dry densities and then reinforced with 5% PS solutions. The specimens with or without PS reinforcement were subjected to disintegration test in water,to wind erosion test in wind tunnel,to temperature fluctuation test,to humidity variation test and to freezethaw test. So,the influences of serious environments of the ancient Silk Road on the reinforcement effect are studied. Specimens reinforced with 5% PS show a better resistance to environment weathering respectively. For example,they have a longer initial disintegration time,a slower disintegration speed,and a higher ability of antiwind erosion and freezethaw,as compared with unreinforced specimensThese results show that the PS reinforcement is still effective and the PS is suitable for conservation of the earthen ruins in arid area of the Silk Road．
Soil specimens were moulded according to different dry densities and then reinforced with 5% PS solutions. The specimens with or without PS reinforcement were subjected to disintegration test in water,to wind erosion test in wind tunnel,to temperature fluctuation test,to humidity variation test and to freezethaw test. So,the influences of serious environments of the ancient Silk Road on the reinforcement effect are studied. Specimens reinforced with 5% PS show a better resistance to environment weathering respectively. For example,they have a longer initial disintegration time,a slower disintegration speed,and a higher ability of antiwind erosion and freezethaw,as compared with unreinforced specimensThese results show that the PS reinforcement is still effective and the PS is suitable for conservation of the earthen ruins in arid area of the Silk Road．
2010, 18(3): 376-384.
Compared with routine vacuum preloading method for consolidation of soft soil for the present combined with the vacuum tube network,horizontal sand blanket and prefabricated vertical drains,straightline vacuum preloading method was improved and was innovated in design to save sand sources and funding. It has been achieved to increase efficiency,improve quality,reduce costs and shorten construction time. Both of the two vacuum preloading methods were analyzed contrastively on the field test of obtained monitoring and detection of areas of data. Straightline vacuum preloading method was significantly improved energy efficiency. Not only did it shorten the prepress time,but saved the material of the mediumcoarse sand and reduced the project cost．
Straightline vacuum preloading, Energy efficiency, Consolidation, Settlement, Pore water pressure, Vacuum, Vaneshear strength
Compared with routine vacuum preloading method for consolidation of soft soil for the present combined with the vacuum tube network,horizontal sand blanket and prefabricated vertical drains,straightline vacuum preloading method was improved and was innovated in design to save sand sources and funding. It has been achieved to increase efficiency,improve quality,reduce costs and shorten construction time. Both of the two vacuum preloading methods were analyzed contrastively on the field test of obtained monitoring and detection of areas of data. Straightline vacuum preloading method was significantly improved energy efficiency. Not only did it shorten the prepress time,but saved the material of the mediumcoarse sand and reduced the project cost．
Straightline vacuum preloading, Energy efficiency, Consolidation, Settlement, Pore water pressure, Vacuum, Vaneshear strength
2010, 18(3): 385-391.
According to experimental theory and method of soil mechanics and rock mechanics,this paper studies equipments,methods requirements for sample remodeling of rocksoil mixtures(RSM). A standard procedure for sample remodeling of RSM is proposed. Compactness characteristic and mechanism of RSM are analyzed by comparing lots of remodeling RSM samples with soil samples. The compactness of RSM in sample remodeling is completed as a result of the compactness of the soil in RSM in fact. The uniaxial compression of RSM is firstly carried out by utilizing highprecision rock test rig. Some important test data are obtained to explore the mechanical behaviors of RSA. It is shown that the compression strength,Youngs modulus of RSM are lower than those of soils under the uniaxial compression,which contradicts to the common consensus. This contradiction could be explained with the poor contact mode between the rock blocks and soils in RSM,where the skeleton structure composed of rock blocks in RSM beard the main loading under unconfined compression while the soils in RSM did little. Overall,the skeleton structure composed of rock blocks in RSM is crucial to the compression strength,Youngs modulus,characteristic of deformation and failure for RSM. It also is an important mechanical behavior of RSM.
According to experimental theory and method of soil mechanics and rock mechanics,this paper studies equipments,methods requirements for sample remodeling of rocksoil mixtures(RSM). A standard procedure for sample remodeling of RSM is proposed. Compactness characteristic and mechanism of RSM are analyzed by comparing lots of remodeling RSM samples with soil samples. The compactness of RSM in sample remodeling is completed as a result of the compactness of the soil in RSM in fact. The uniaxial compression of RSM is firstly carried out by utilizing highprecision rock test rig. Some important test data are obtained to explore the mechanical behaviors of RSA. It is shown that the compression strength,Youngs modulus of RSM are lower than those of soils under the uniaxial compression,which contradicts to the common consensus. This contradiction could be explained with the poor contact mode between the rock blocks and soils in RSM,where the skeleton structure composed of rock blocks in RSM beard the main loading under unconfined compression while the soils in RSM did little. Overall,the skeleton structure composed of rock blocks in RSM is crucial to the compression strength,Youngs modulus,characteristic of deformation and failure for RSM. It also is an important mechanical behavior of RSM.
2010, 18(3): 392-397.
In real projects,soils under foundations or roadbeds are usually in complex initial stress state,deformation and settlement happens under earthquakes or other dynamic loadings. Conventional laboratory experiments of soils cannot authentically reproduce dynamic behaviors of soils under this kind of consolidation stress conditionsAfter having reformed the DTC199 torsional cyclic load triaxial apparatus,dynamic deformation of compacted loess can be tested when the initial principal stress axis is rotated. Results show that the initial angle of the principal stress has an influence on the dynamic shear modulus of the compacted loess when other consolidation conditions are fixed. As increases,the dynamic shear modulus shows a decreasing trend,and the maximum dynamic shear stress reduces gradually. But does not considerably influence the maximum dynamic shear modulus. The initial angle of the principal stress has basically no influence on the damping ratio of compacted loess. The damping ratio has an increasing trend with the increase of dynamic shear strain in the semilog plot of -lgd,and they show good relativity．
In real projects,soils under foundations or roadbeds are usually in complex initial stress state,deformation and settlement happens under earthquakes or other dynamic loadings. Conventional laboratory experiments of soils cannot authentically reproduce dynamic behaviors of soils under this kind of consolidation stress conditionsAfter having reformed the DTC199 torsional cyclic load triaxial apparatus,dynamic deformation of compacted loess can be tested when the initial principal stress axis is rotated. Results show that the initial angle of the principal stress has an influence on the dynamic shear modulus of the compacted loess when other consolidation conditions are fixed. As increases,the dynamic shear modulus shows a decreasing trend,and the maximum dynamic shear stress reduces gradually. But does not considerably influence the maximum dynamic shear modulus. The initial angle of the principal stress has basically no influence on the damping ratio of compacted loess. The damping ratio has an increasing trend with the increase of dynamic shear strain in the semilog plot of -lgd,and they show good relativity．
2010, 18(3): 398-406.
After the No.14 shaft was repaired in Jinchuan No.2 mine,two big cracks were formed in the new shaft well. Therefore,further reinforcement program was put forward on the repaired shaft. Based on GPS monitoring data of ground surface movement, this paper evaluated the feasibility of the reinforcement program of No.14 shaft by numerical simulation. The results show that the shallow reinforcement measure did not change the extent of mining impact on the shaft,and the reinforcement method did not achieve the desired effect. Then,the prestressed cable reinforcement was used for inspecting the adaptability of this strengthening program. It was further found the level and distribution of shaft wall displacement and stress did not change significantly before and after the reinforcement. This shows that only shallow reinforcement program was not effective for the shaft which located in the severely affected region of rock movement induced by underground mining. It was a useful guide for engineering design and had practical significance in mining production. Finally,further reinforcement program was suggested after considering damage reasons of No.14 shaft,problems in the former inforcement program,as well as trends of rock movement．
After the No.14 shaft was repaired in Jinchuan No.2 mine,two big cracks were formed in the new shaft well. Therefore,further reinforcement program was put forward on the repaired shaft. Based on GPS monitoring data of ground surface movement, this paper evaluated the feasibility of the reinforcement program of No.14 shaft by numerical simulation. The results show that the shallow reinforcement measure did not change the extent of mining impact on the shaft,and the reinforcement method did not achieve the desired effect. Then,the prestressed cable reinforcement was used for inspecting the adaptability of this strengthening program. It was further found the level and distribution of shaft wall displacement and stress did not change significantly before and after the reinforcement. This shows that only shallow reinforcement program was not effective for the shaft which located in the severely affected region of rock movement induced by underground mining. It was a useful guide for engineering design and had practical significance in mining production. Finally,further reinforcement program was suggested after considering damage reasons of No.14 shaft,problems in the former inforcement program,as well as trends of rock movement．
2010, 18(3): 407-412.
The No.2 ventilation shaft of Qinling highway tunnel is mainly located in the mixed gneiss stratum. The main technical problems encountered in the shaft excavation are high insitu geostress and rockburst. The paper examined the engineering geology of the shaft and the geostress measurement results of nearby engineering by hydraulic fracturing method. Then, the geostress field in the shaft area is calculated and regressed with 3D finite element method. It is shown that the geostress in the shaft area has a high horizontal geological structure stress and is ly distributed in zones. The maximum horizontal geostress is 28.7 MPa. The vertical geostress is controlled by weight of rockmass. Based on the geostress field, the rockburst prediction in the shaft is made according to the Tao's rockburst criteria. The depth of rockburst failure area is estimated with the constantdeviatoricstresscriterion of brittle rock mass. The results show that there are high possibilities of occurring weak and moderate rockbursts. The maximum depth of failure is 0.6 m in the surrounding rocks of the shaft. The results from the geostress and rockburst analysis are well compared with the actual situations of rockbursts after shaft excavation.
The No.2 ventilation shaft of Qinling highway tunnel is mainly located in the mixed gneiss stratum. The main technical problems encountered in the shaft excavation are high insitu geostress and rockburst. The paper examined the engineering geology of the shaft and the geostress measurement results of nearby engineering by hydraulic fracturing method. Then, the geostress field in the shaft area is calculated and regressed with 3D finite element method. It is shown that the geostress in the shaft area has a high horizontal geological structure stress and is ly distributed in zones. The maximum horizontal geostress is 28.7 MPa. The vertical geostress is controlled by weight of rockmass. Based on the geostress field, the rockburst prediction in the shaft is made according to the Tao's rockburst criteria. The depth of rockburst failure area is estimated with the constantdeviatoricstresscriterion of brittle rock mass. The results show that there are high possibilities of occurring weak and moderate rockbursts. The maximum depth of failure is 0.6 m in the surrounding rocks of the shaft. The results from the geostress and rockburst analysis are well compared with the actual situations of rockbursts after shaft excavation.
2010, 18(3): 413-418.
The Shaqu Coal Mine is a typical compound roof mine. Its engineering geological conditions are affected by the multistrip structural zones. The roof and floor of the working face are composed of instability soft rocks. There is little water in the fractures. This paper investigates the characteristics of the insitu stress and ground overburden pressure. The Insitu stress testing of six sites were carried out in some main roadways. The test results indicate that insitu stress field is relatively uniform and belongs to the quasihydrostatic stress. The stress trepanning rescission and the surrounding pressure ratio measuring are applied. The tests find that the maximum principal stress value is between 2011 and 287 MPa. The coefficient of the horizontal pressure value is between n 225 and 285. The results show the site is of high stress. Local monitoring works of coal pillar bearing pressure are performed for the large and high fullymechanized mining roadway of the No. 24101 working face. Distribution of coal pillar bearing pressure of stope can be divided into a plastic failure region,a peak stress region and an in situ stress region. At the same time,the roof separation and bolt dynamometer load are monitored for the No. 14201 work face of the south side mine. The monitoring reveals that the main reason of weakened roadway stabilization is the accretion of roof separation with time increasing. These synthetic monitoring results can provide more practical value and basic data for design of the supporting and safety during the mine production.
The Shaqu Coal Mine is a typical compound roof mine. Its engineering geological conditions are affected by the multistrip structural zones. The roof and floor of the working face are composed of instability soft rocks. There is little water in the fractures. This paper investigates the characteristics of the insitu stress and ground overburden pressure. The Insitu stress testing of six sites were carried out in some main roadways. The test results indicate that insitu stress field is relatively uniform and belongs to the quasihydrostatic stress. The stress trepanning rescission and the surrounding pressure ratio measuring are applied. The tests find that the maximum principal stress value is between 2011 and 287 MPa. The coefficient of the horizontal pressure value is between n 225 and 285. The results show the site is of high stress. Local monitoring works of coal pillar bearing pressure are performed for the large and high fullymechanized mining roadway of the No. 24101 working face. Distribution of coal pillar bearing pressure of stope can be divided into a plastic failure region,a peak stress region and an in situ stress region. At the same time,the roof separation and bolt dynamometer load are monitored for the No. 14201 work face of the south side mine. The monitoring reveals that the main reason of weakened roadway stabilization is the accretion of roof separation with time increasing. These synthetic monitoring results can provide more practical value and basic data for design of the supporting and safety during the mine production.
2010, 18(3): 419-424.
The impact of seepage field on deep and thick overburden mainly manifests in the physical,chemical and mechanical aspects of the ground. In this paper,a deep and thick overburden in typical place of Ludila hydropower reservoir banks on Jinsha River is used as examples of stability analysis after reservoir impounding. The site has a detailed ground investigation. The ground investigation includes geological structure,material composition,hierarchical feature,physical and mechanical properties,grain composition and infiltration parameters. Using those data,the deformation of deep and thick overburden is computed with a threedimensional finite element program. The seepage aspect to the deep overburden is analyzed. The results show that after the river water level elevates 5 meters,the seepage changes. Under the effect of osmotic pressure,the deformations on the parallel and perpendicular direction to the river are different. The largest deformation on the parallel direction to the river is 50 cm. The largest deformation on the perpendicular direction to the river is 133 cm. The largest decrease in production is 188 cm. Such a large deformation can cause deep overburden damage,thereby affect its upper buildings and road safety．
The impact of seepage field on deep and thick overburden mainly manifests in the physical,chemical and mechanical aspects of the ground. In this paper,a deep and thick overburden in typical place of Ludila hydropower reservoir banks on Jinsha River is used as examples of stability analysis after reservoir impounding. The site has a detailed ground investigation. The ground investigation includes geological structure,material composition,hierarchical feature,physical and mechanical properties,grain composition and infiltration parameters. Using those data,the deformation of deep and thick overburden is computed with a threedimensional finite element program. The seepage aspect to the deep overburden is analyzed. The results show that after the river water level elevates 5 meters,the seepage changes. Under the effect of osmotic pressure,the deformations on the parallel and perpendicular direction to the river are different. The largest deformation on the parallel direction to the river is 50 cm. The largest deformation on the perpendicular direction to the river is 133 cm. The largest decrease in production is 188 cm. Such a large deformation can cause deep overburden damage,thereby affect its upper buildings and road safety．
2010, 18(3): 425-430.
Spillway slope deformation can be caused by infiltration of rain and fog. It turns to affect the stability of the slope. It has become one of the important problems of the construction of hydropower stations. This paper is based on the structural features of slope slippage belt,cracks and control joints structure developing in atomized slope in the chute segment of the spillway in one southwest hydropower station. It analysis the boundary conditions and deformation and failure modes of potential instability in the condition of flood discharge atomization after the excavation and supporting of the slope. It examines the geological environment conditions of the slope. It uses the mechanism of the flood discharge atomization role on the rock slope. It finds that the major impact of rain and fog to slope is infiltration of rain and fog along the tension crack surfaces of the slope. The infiltration influences the mechanical properties of the structural plane,thus affects the stability of the slope. The analysis of the deformation characteristics is carried out on structural plane of the different softening coefficient in the slope. The trend of the slope deformation and failure after the infiltration of flood discharge atomizing rain and fog is further analyzed using numerical simulation. The results show that different softening coefficients can result in a larger difference among the downstream side slope rock mass of the spillway 0+55500. If the coefficient is the mid value of 075,the spillway chute slope is less stable,and probably has a shear creep deformation or block failure. So it is necessary to strengthen certain support measures to ensure the safety of the slope during the construction period and the longterm stability in the period of the operation．
Spillway slope deformation can be caused by infiltration of rain and fog. It turns to affect the stability of the slope. It has become one of the important problems of the construction of hydropower stations. This paper is based on the structural features of slope slippage belt,cracks and control joints structure developing in atomized slope in the chute segment of the spillway in one southwest hydropower station. It analysis the boundary conditions and deformation and failure modes of potential instability in the condition of flood discharge atomization after the excavation and supporting of the slope. It examines the geological environment conditions of the slope. It uses the mechanism of the flood discharge atomization role on the rock slope. It finds that the major impact of rain and fog to slope is infiltration of rain and fog along the tension crack surfaces of the slope. The infiltration influences the mechanical properties of the structural plane,thus affects the stability of the slope. The analysis of the deformation characteristics is carried out on structural plane of the different softening coefficient in the slope. The trend of the slope deformation and failure after the infiltration of flood discharge atomizing rain and fog is further analyzed using numerical simulation. The results show that different softening coefficients can result in a larger difference among the downstream side slope rock mass of the spillway 0+55500. If the coefficient is the mid value of 075,the spillway chute slope is less stable,and probably has a shear creep deformation or block failure. So it is necessary to strengthen certain support measures to ensure the safety of the slope during the construction period and the longterm stability in the period of the operation．
Due to the restriction of landform,bridge foundation can only be placed on thin and weak sea reefs,the type and embedded depth of the bridge foundation are controlled by the quality of the sea reefs. Associated with the Laohu Mountain of the practice of Xihoumen bridge in Zhoushan mainland link project,in allusion to its geological conditions of large span and high tower bridge foundation,based on an overall consideration of different parts(that is above,below the water and the intertidal zone),propose using rock mechanical property,rock mass structure type,characteristics of discontinuities(especially controlled by weak discontinuities),weathering conditions and groundwater conditions(affected by tidal action)as controlling factors,and use uniaxial saturated compressive strength Rs,rock quality designation index RQD,rock mass integrality coefficient Kv,weathering degree coefficient KY and groundwater correction coefficient U to quantify the classification factors mentioned above,and build up a composite index Z=RsRQDKvKY+U to reflect the quality of sea reefs,and establish the classification system of different grades of rock mass．
Due to the restriction of landform,bridge foundation can only be placed on thin and weak sea reefs,the type and embedded depth of the bridge foundation are controlled by the quality of the sea reefs. Associated with the Laohu Mountain of the practice of Xihoumen bridge in Zhoushan mainland link project,in allusion to its geological conditions of large span and high tower bridge foundation,based on an overall consideration of different parts(that is above,below the water and the intertidal zone),propose using rock mechanical property,rock mass structure type,characteristics of discontinuities(especially controlled by weak discontinuities),weathering conditions and groundwater conditions(affected by tidal action)as controlling factors,and use uniaxial saturated compressive strength Rs,rock quality designation index RQD,rock mass integrality coefficient Kv,weathering degree coefficient KY and groundwater correction coefficient U to quantify the classification factors mentioned above,and build up a composite index Z=RsRQDKvKY+U to reflect the quality of sea reefs,and establish the classification system of different grades of rock mass．
微信 | 公众平台 
