2010 Vol. 18, No. 5

论文
Brittle rock mass generally reserves high strain energy under high ground stress condition.As it is excavated,rock burst will take place with a rapid release of reserved energy.This paper explores the mechanism of rock burst and obtained the following points: (1) Phenomena have shown that rock burst is possibly a kind of tensile and tension-shear failure and the failure angle is relatively small.It is pointed out that excavation can induce tensional stress state in rock mass.(2) Two and three dimensional criterions for rock burst based on Griffith theory have been proposed,and the theoretical analysis has confirmed that the failure angle will be reduced with the occurrence of tensional stress state,till zero while pure tensional state. (3) The energy analysis has shown that the energy consumed for pure tensional failure is relatively less than that for tension-shear failure or compressive-shear failure.And the strain energy dissipated in failure will mainly transferred into surface energy for newly created cracks and the kinetic energy of the failure pieces of rock.Theoretical analysis has proved that the proportion of kinetic energy is much bigger than that for surface energy. (4) The probable applications of this theory include: predicts the failure mode,location and size of rock burst; and theoretical basis of stress control for excavation design. Brittle rock mass generally reserves high strain energy under high ground stress condition.As it is excavated,rock burst will take place with a rapid release of reserved energy.This paper explores the mechanism of rock burst and obtained the following points: (1) Phenomena have shown that rock burst is possibly a kind of tensile and tension-shear failure and the failure angle is relatively small.It is pointed out that excavation can induce tensional stress state in rock mass.(2) Two and three dimensional criterions for rock burst based on Griffith theory have been proposed,and the theoretical analysis has confirmed that the failure angle will be reduced with the occurrence of tensional stress state,till zero while pure tensional state. (3) The energy analysis has shown that the energy consumed for pure tensional failure is relatively less than that for tension-shear failure or compressive-shear failure.And the strain energy dissipated in failure will mainly transferred into surface energy for newly created cracks and the kinetic energy of the failure pieces of rock.Theoretical analysis has proved that the proportion of kinetic energy is much bigger than that for surface energy. (4) The probable applications of this theory include: predicts the failure mode,location and size of rock burst; and theoretical basis of stress control for excavation design.
From 12 to 14 of August 2010,heavy rain even rainstorms have been dropped in part of area in Sichuan province,and catastrophic debris flow have been induced in Qingping town of Mianzhu city,Yingxiu town of Wenchuan county and Longchi town of Dujiangyan city,which belonged to the worst-hit areas of the 5 12 Wenchuan earthquake.This disaster was referred by government as the 13 August 2010 catastrophic debris flow in Sichuan province.This debris flow disaster demonstrated that the debris flow in seismic zone or in none-seismic zone,pre-earthquake or post-earthquake had significant differences in distribution,forming condition,scale,moving style as well as other disaster mode and harmfulness.Firstly,a brief introduction to the 8 13 Qingping,Hongchungou of Yingxiu and Longchi debris flows have been made in this paper.The characteristic and formation reason of the 8 13 catastrophic debris flow,in Wenchuan earthquake region,have been analyzed and summarized and several revelations and suggestions to the prevention of the debris flow in disaster area have been put forward.The research result showed that the 8 13 debris flow not only had the characteristics of group properties,sudden features,destructiveness and hazard chain effect,but also had the significant characteristics of zonal distribution along the seismic fault,materials mainly coming from rock slide deposit which triggered by the Wenchuan earthquake and down-cutting being the mainly moving mode.Extraordinary abundant loose solid materials and local short-time heavy rainfall by the extreme climate in the earthquake region were the basic reason of the debris flow occurrence.In allusion to these new characteristics of the debris flow in Wenchuan earthquake region,the prevention measures to debris flow in earthquake region should be strengthened,especially those valleys of great debris flow hidden trouble.On the one hand,the standard of the garrison should be improved and the engineering management as well as specialty monitor should be intensified.On the other hand,risk management and control ideal should be brought in.The combination of prevention and administration,the combination of soft and hard,the combination of engineering measures and non-engineering measures,and the combination of administration and management was supposed to be focused on.What else,mobilizing the whole society to prevent geological disaster all together. From 12 to 14 of August 2010,heavy rain even rainstorms have been dropped in part of area in Sichuan province,and catastrophic debris flow have been induced in Qingping town of Mianzhu city,Yingxiu town of Wenchuan county and Longchi town of Dujiangyan city,which belonged to the worst-hit areas of the 5 12 Wenchuan earthquake.This disaster was referred by government as the 13 August 2010 catastrophic debris flow in Sichuan province.This debris flow disaster demonstrated that the debris flow in seismic zone or in none-seismic zone,pre-earthquake or post-earthquake had significant differences in distribution,forming condition,scale,moving style as well as other disaster mode and harmfulness.Firstly,a brief introduction to the 8 13 Qingping,Hongchungou of Yingxiu and Longchi debris flows have been made in this paper.The characteristic and formation reason of the 8 13 catastrophic debris flow,in Wenchuan earthquake region,have been analyzed and summarized and several revelations and suggestions to the prevention of the debris flow in disaster area have been put forward.The research result showed that the 8 13 debris flow not only had the characteristics of group properties,sudden features,destructiveness and hazard chain effect,but also had the significant characteristics of zonal distribution along the seismic fault,materials mainly coming from rock slide deposit which triggered by the Wenchuan earthquake and down-cutting being the mainly moving mode.Extraordinary abundant loose solid materials and local short-time heavy rainfall by the extreme climate in the earthquake region were the basic reason of the debris flow occurrence.In allusion to these new characteristics of the debris flow in Wenchuan earthquake region,the prevention measures to debris flow in earthquake region should be strengthened,especially those valleys of great debris flow hidden trouble.On the one hand,the standard of the garrison should be improved and the engineering management as well as specialty monitor should be intensified.On the other hand,risk management and control ideal should be brought in.The combination of prevention and administration,the combination of soft and hard,the combination of engineering measures and non-engineering measures,and the combination of administration and management was supposed to be focused on.What else,mobilizing the whole society to prevent geological disaster all together.
At about 4 oclock on July 27, 2010,a large-scale rock slide happened in Ermanshan of Han Yuan in Sichuan province.Under the influence of the early rainfall,approximately 48104m3 strongly weathered basalt mass in high position slid down at a high speed,and then disrupted,transferred into debris flow,made a rapid movement along the valley,and unceasingly entrained and scraped the superficial loose material accumulating in the gully bed and on both sides of slopes,which caused the unceasingly increase of the volume and water content of debris flow.When moving to the middle part of the valley,because of the trench orienting towards right here,a part of debris flow ran to the left bank of the slope under the influence of strong inertia force,burying five villagers houses of ShuangHe village and causing 20 people missed.The other part of debris flow didnt stop moving until it ran rapidly for about 1.4km along the trench.The landslide drift accumulating in the middle part of the deep-river-cut trench started again under gravity form a secondary landslide.After creeping slip for several hours,the secondary landslide eventually arrived at WanGong Town and crushed down some houses,causing 92 houses to be damaged and 1500 people to be evacuate urgently.This paper carries out a detailed investigation and research on the zonal characteristics of the Ermanshan rock slide-debris flow and preliminary analysis of the disaster causes on the basis of massive geologic investigation into the site of the disaster,combined with in-situ measurement,experimentation,aerial photography and other means.The result indicates that the relatively prominent terrain condition of the source area,the weathered and shattered basalt mass and favorable combination of discontinuities is the fundamental condition for the rock slide.The debris flow undercutting the base of slope,the saturated surcharge of the rainfall,and the rainfalls infiltrating and softening effect along the sub-vertical and tensile texture plane directly caused the landslide.Ermanshan trench was originally a valley where debris flow frequently happened.There is no obvious signal before landslide happens.When it occurs,it demonstrates some characteristics as confidentiality,strong paroxysm,danger in long-rang movement in high position at a high speed and so on.Meanwhile,in a short time after the landslide,a secondary landslide will happen in the sliding zone.These phenomena and characteristics are special and typical.They are worth a further study. At about 4 oclock on July 27, 2010,a large-scale rock slide happened in Ermanshan of Han Yuan in Sichuan province.Under the influence of the early rainfall,approximately 48104m3 strongly weathered basalt mass in high position slid down at a high speed,and then disrupted,transferred into debris flow,made a rapid movement along the valley,and unceasingly entrained and scraped the superficial loose material accumulating in the gully bed and on both sides of slopes,which caused the unceasingly increase of the volume and water content of debris flow.When moving to the middle part of the valley,because of the trench orienting towards right here,a part of debris flow ran to the left bank of the slope under the influence of strong inertia force,burying five villagers houses of ShuangHe village and causing 20 people missed.The other part of debris flow didnt stop moving until it ran rapidly for about 1.4km along the trench.The landslide drift accumulating in the middle part of the deep-river-cut trench started again under gravity form a secondary landslide.After creeping slip for several hours,the secondary landslide eventually arrived at WanGong Town and crushed down some houses,causing 92 houses to be damaged and 1500 people to be evacuate urgently.This paper carries out a detailed investigation and research on the zonal characteristics of the Ermanshan rock slide-debris flow and preliminary analysis of the disaster causes on the basis of massive geologic investigation into the site of the disaster,combined with in-situ measurement,experimentation,aerial photography and other means.The result indicates that the relatively prominent terrain condition of the source area,the weathered and shattered basalt mass and favorable combination of discontinuities is the fundamental condition for the rock slide.The debris flow undercutting the base of slope,the saturated surcharge of the rainfall,and the rainfalls infiltrating and softening effect along the sub-vertical and tensile texture plane directly caused the landslide.Ermanshan trench was originally a valley where debris flow frequently happened.There is no obvious signal before landslide happens.When it occurs,it demonstrates some characteristics as confidentiality,strong paroxysm,danger in long-rang movement in high position at a high speed and so on.Meanwhile,in a short time after the landslide,a secondary landslide will happen in the sliding zone.These phenomena and characteristics are special and typical.They are worth a further study.
The Dazhai event happened at Jun 28, 2010 in Guling county of Guizhou province of China.It is a sliding in rockfall and debris events(volume is about 78.8104m3),and an oversize geological disaster(the number of missing and death is 99 residents).It is taken for that rockmass breakdown results mainly from dry building block structure in fissured rockmass in internality of Dazhai slope by through field looking into collapse phenomena.That sustaining water wedge pressure acts on the crown cracks by pouring rainwater from extreme rainstorm,process rainfall reach to 237mm,is main external triggering factor which result in slope rockmass loosening,toppling,rotating and falling finally.The grain size distribution of debris(crushed stone)flow is to change small gradually from rockfall headstream to stop outlet of the ditch.Still,its impact height is to knock down and strike velocity is to be decrease gradually.The total process of the debris(crushed stone)flow displays that multilevel of potential energy transform into same number of kinetic energy and accordingly occur in multi-strike paths.Based on the law of conservation of energy,maximum velocity in each strike path is calculated and obtain that first stage belongs to rockfall and slip in high velocity(V1=24.25m s-1),others are debris(crushed stone)flows.It is not discovered that direct evidences of the event exist related with natural earthquakes,Guangzhao reservoir induced seismic activity and historic coal mining in the region.Moreover,it may be predicted that possibility of debris flow happening again is existent because there are unstable rockmasses in collapse area and dammed ponds in the debris deposits of 3~5m in diameter that show capacity for to drainage to be not enough in open space of crushed stones. The Dazhai event happened at Jun 28, 2010 in Guling county of Guizhou province of China.It is a sliding in rockfall and debris events(volume is about 78.8104m3),and an oversize geological disaster(the number of missing and death is 99 residents).It is taken for that rockmass breakdown results mainly from dry building block structure in fissured rockmass in internality of Dazhai slope by through field looking into collapse phenomena.That sustaining water wedge pressure acts on the crown cracks by pouring rainwater from extreme rainstorm,process rainfall reach to 237mm,is main external triggering factor which result in slope rockmass loosening,toppling,rotating and falling finally.The grain size distribution of debris(crushed stone)flow is to change small gradually from rockfall headstream to stop outlet of the ditch.Still,its impact height is to knock down and strike velocity is to be decrease gradually.The total process of the debris(crushed stone)flow displays that multilevel of potential energy transform into same number of kinetic energy and accordingly occur in multi-strike paths.Based on the law of conservation of energy,maximum velocity in each strike path is calculated and obtain that first stage belongs to rockfall and slip in high velocity(V1=24.25m s-1),others are debris(crushed stone)flows.It is not discovered that direct evidences of the event exist related with natural earthquakes,Guangzhao reservoir induced seismic activity and historic coal mining in the region.Moreover,it may be predicted that possibility of debris flow happening again is existent because there are unstable rockmasses in collapse area and dammed ponds in the debris deposits of 3~5m in diameter that show capacity for to drainage to be not enough in open space of crushed stones.
The seismic geological context,morphology,formation mechanism and evolution of Wenjiagou high-speed and long-runout debris avalanche are introduced. The debris avalanche was located at Wenjiaogou syncline block between Yingxiu-Beichuan fault and Guanxian-Anxian fault of which severe activity provides precondition for the debris avalanche. It is 1360m high from the peak of debris avalanche source area to Wenjiagou valley mouth; seismic load shows remarkable amplification effect at the ridge due to the terrain of towering hill with deep valley at the foot,and directly results in the landslide. The peak values of ground motion acceleration in 3 directions in the ridge are aEW=2.4g,aNS=2.3g,aUP=1.2g(g: the acceleration of gravity). The Guanwushan formation(D2gn)limestone slope has layered structure with progressive strength. About 50m below the slope surface is loose structural Qel+dl~upper part of fresh rock,which is cut into initial landslide mass results from the tension-compression and shear coupling effect due to seismic P-wave and S-wave. The sliding mass shear out from edge of the 8th platform; the maximum traveling velocity of sliding mass is accelerated up to 93~122m s-1 in Wenjiagou valley upstream. Trapped air inside of the valley is compressed by upper part of landslide mass,the dry debris flow,at 2 turnings of Wenjiagou valley; distinct air cushion effect is generated. Besides,the bottom layer of debris flow is liquefied; effective dynamic friction coefficient is decreased with increasing of shearing velocity; all of these effects lead to the high-speed and long-runout traveling of debris flow. Simultaneously,the valley slope is scraped and crossed; the trees are cut as debris flow passes. After Wenchuan earthquake,up to Sept. 2009,rainfall has triggered several debris flows,which indicates the continuity and long-term nature of seismic geohazard. The seismic geological context,morphology,formation mechanism and evolution of Wenjiagou high-speed and long-runout debris avalanche are introduced. The debris avalanche was located at Wenjiaogou syncline block between Yingxiu-Beichuan fault and Guanxian-Anxian fault of which severe activity provides precondition for the debris avalanche. It is 1360m high from the peak of debris avalanche source area to Wenjiagou valley mouth; seismic load shows remarkable amplification effect at the ridge due to the terrain of towering hill with deep valley at the foot,and directly results in the landslide. The peak values of ground motion acceleration in 3 directions in the ridge are aEW=2.4g,aNS=2.3g,aUP=1.2g(g: the acceleration of gravity). The Guanwushan formation(D2gn)limestone slope has layered structure with progressive strength. About 50m below the slope surface is loose structural Qel+dl~upper part of fresh rock,which is cut into initial landslide mass results from the tension-compression and shear coupling effect due to seismic P-wave and S-wave. The sliding mass shear out from edge of the 8th platform; the maximum traveling velocity of sliding mass is accelerated up to 93~122m s-1 in Wenjiagou valley upstream. Trapped air inside of the valley is compressed by upper part of landslide mass,the dry debris flow,at 2 turnings of Wenjiagou valley; distinct air cushion effect is generated. Besides,the bottom layer of debris flow is liquefied; effective dynamic friction coefficient is decreased with increasing of shearing velocity; all of these effects lead to the high-speed and long-runout traveling of debris flow. Simultaneously,the valley slope is scraped and crossed; the trees are cut as debris flow passes. After Wenchuan earthquake,up to Sept. 2009,rainfall has triggered several debris flows,which indicates the continuity and long-term nature of seismic geohazard.
From Yunyang to Jiangjin of the Three Gorges Reservoir,the geological environment is complicated. The dangerous rocks can be the main geological hazard. Rupture of the rocks is abrupt while calamity is catastropic.The stability factors of dangerous rocks are complicated and fuzzy.Their basic conditions to develop in the area classify as strong unloading agent by cutting of river or ravines lithological composition with weak or hard features.In this paper,seven factors are selected. They can influence the occurrence of fall and can be used as evaluation indices.They included phsiognomy,rock property,structure of rock mass,rock scale,hydrogeological conditions,weathering and land use type.A risk index model is obtained. Four grades are divided according to the dangerous rock stability index: stability,potential unstable,unstable,very unstable. Results of real examples are consistent with the survey.The results show that much more information are considered in the model and the data can be obtained easily.At the same time,the selection of assessment index and gradation is coincident with the fact.The model can provide significant reference to the survey and supervision for reinforcing dangerous rock in the Three Gorges Reservoir. From Yunyang to Jiangjin of the Three Gorges Reservoir,the geological environment is complicated. The dangerous rocks can be the main geological hazard. Rupture of the rocks is abrupt while calamity is catastropic.The stability factors of dangerous rocks are complicated and fuzzy.Their basic conditions to develop in the area classify as strong unloading agent by cutting of river or ravines lithological composition with weak or hard features.In this paper,seven factors are selected. They can influence the occurrence of fall and can be used as evaluation indices.They included phsiognomy,rock property,structure of rock mass,rock scale,hydrogeological conditions,weathering and land use type.A risk index model is obtained. Four grades are divided according to the dangerous rock stability index: stability,potential unstable,unstable,very unstable. Results of real examples are consistent with the survey.The results show that much more information are considered in the model and the data can be obtained easily.At the same time,the selection of assessment index and gradation is coincident with the fact.The model can provide significant reference to the survey and supervision for reinforcing dangerous rock in the Three Gorges Reservoir.
Ground-water depletion and preliminary fault are the main factors arousing the ground fissures hazard in Xi'an City.Firstly,the tensile crack machanisim,shear crack machanisim,shear and tensile multiple machanisim of the ground fissure are analysis in theory,and the controling role of the preliminary fault on the causes of ground fissure is analysed based on structrual plane controling theory; Then,authors set up a numerical simulation model with three dimension biot consolidation theory,through this model,the displacement of three cases,pumping without preliminary fault,pumping with preliminary fault,pumping without preliminary fault but with stratum diffrence,are compared,the authors found that the preliminary fault is not only the tectonic foundation,but also has induction,amplification and segregation fuction on the formation and development of the ground fissues. Ground-water depletion and preliminary fault are the main factors arousing the ground fissures hazard in Xi'an City.Firstly,the tensile crack machanisim,shear crack machanisim,shear and tensile multiple machanisim of the ground fissure are analysis in theory,and the controling role of the preliminary fault on the causes of ground fissure is analysed based on structrual plane controling theory; Then,authors set up a numerical simulation model with three dimension biot consolidation theory,through this model,the displacement of three cases,pumping without preliminary fault,pumping with preliminary fault,pumping without preliminary fault but with stratum diffrence,are compared,the authors found that the preliminary fault is not only the tectonic foundation,but also has induction,amplification and segregation fuction on the formation and development of the ground fissues.
At 14: 28,on 12 May 2008,the earthquake occurred at Richter scale 8.0 at Wenchuan county,Sichuan province and more than 30 barrier lakes came into being,which made a great threat on peoples life and property and drew great attention from all over the world. On the base of previous research,the paper summarizes the mechanism of forming and existence of barrier dams from topography and geomorphology,induced factors and lifetime. The focus is on the research progress of the stability of barrier dams. It is pointed out that the internal causes of the stability of barriers are morphology and scale,material composition and structure of barrier dams,and that the external causes is the volume of barrier lake. Then the paper summarizes the previous research results of key causes of the stability of barriers and of indoor model test. At last,the existing problems and future research direction of barrier dams is pointed out. At 14: 28,on 12 May 2008,the earthquake occurred at Richter scale 8.0 at Wenchuan county,Sichuan province and more than 30 barrier lakes came into being,which made a great threat on peoples life and property and drew great attention from all over the world. On the base of previous research,the paper summarizes the mechanism of forming and existence of barrier dams from topography and geomorphology,induced factors and lifetime. The focus is on the research progress of the stability of barrier dams. It is pointed out that the internal causes of the stability of barriers are morphology and scale,material composition and structure of barrier dams,and that the external causes is the volume of barrier lake. Then the paper summarizes the previous research results of key causes of the stability of barriers and of indoor model test. At last,the existing problems and future research direction of barrier dams is pointed out.
Debris flow is a kind of disaster,which happens frequently and has serious harm to the nature. Longnan,as one of the very severe areas,hit by debris flows,landslides not only seriously impede the normal operation of G212,but also affected the regions economic development and peoples lives. Through dealing with the investigation statistics of the 232 debris flow gullies along G212 Longnan section in different attributes,different stages of development,as well as the different degree of harm,and combining the fractal theory,we have analyzed the quantitative relationship between the debris flow number and the landscape elements. The results indicate that topographic factors have different influences on debris flow with different attribute,different stages of development and different degree of damages; to some extent,integrated fractal dimension,shape parameters and terrain slope parameters in forming regions all can reflect the quantification features of different types of debris flow. Debris flow is a kind of disaster,which happens frequently and has serious harm to the nature. Longnan,as one of the very severe areas,hit by debris flows,landslides not only seriously impede the normal operation of G212,but also affected the regions economic development and peoples lives. Through dealing with the investigation statistics of the 232 debris flow gullies along G212 Longnan section in different attributes,different stages of development,as well as the different degree of harm,and combining the fractal theory,we have analyzed the quantitative relationship between the debris flow number and the landscape elements. The results indicate that topographic factors have different influences on debris flow with different attribute,different stages of development and different degree of damages; to some extent,integrated fractal dimension,shape parameters and terrain slope parameters in forming regions all can reflect the quantification features of different types of debris flow.
The Himalayan region,locating in the south of Qinghai-Tibet Plateau,is characterized with the fastest uplifting and actively dynamic motion.This area is one of the worst landslides hit areas in China.The serious landslide disasters have brought great harm to the national economic and social development.With the aid of imagery interpretation and field investigation,the paper studies the distribution of the serious landslide disaster and its relationship with lithology,and divides the lithology in the region into 13 engineering geology rock groups as follows: loose rock group,soft rock group,soft rock mixed with secondary soft rock group,soft rock mixed with secondary hard rock group,secondary soft rock group,secondary soft rock mixed with soft rock,secondary soft rock mixed with secondary hard rock group,secondary soft rock mixed with hard rock group,double-layer with secondary hard rock and secondary soft rock group,secondary hard rock mixed with soft rock group,secondary hard rock mixed with secondary soft rock group,secondary hard rock group,hard rock group.Then the paper concludes that the great landslides prompt to occur in the soft rock group,secondary hard rock mixed with secondary soft rock group and hard rock group; however there is few great landslides occurred in the soft rock mixed with secondary soft rock group,secondary soft rock mixed with secondary hard rock group.The distribution characteristics of the great landslides have indicated the complicated relationship between the formation lithology and occurrence of the great landslides: on the one hand,the soft rock area is too weak to slide,on the other hand,the steep and high area dominated with hard rock often tend to slide. The Himalayan region,locating in the south of Qinghai-Tibet Plateau,is characterized with the fastest uplifting and actively dynamic motion.This area is one of the worst landslides hit areas in China.The serious landslide disasters have brought great harm to the national economic and social development.With the aid of imagery interpretation and field investigation,the paper studies the distribution of the serious landslide disaster and its relationship with lithology,and divides the lithology in the region into 13 engineering geology rock groups as follows: loose rock group,soft rock group,soft rock mixed with secondary soft rock group,soft rock mixed with secondary hard rock group,secondary soft rock group,secondary soft rock mixed with soft rock,secondary soft rock mixed with secondary hard rock group,secondary soft rock mixed with hard rock group,double-layer with secondary hard rock and secondary soft rock group,secondary hard rock mixed with soft rock group,secondary hard rock mixed with secondary soft rock group,secondary hard rock group,hard rock group.Then the paper concludes that the great landslides prompt to occur in the soft rock group,secondary hard rock mixed with secondary soft rock group and hard rock group; however there is few great landslides occurred in the soft rock mixed with secondary soft rock group,secondary soft rock mixed with secondary hard rock group.The distribution characteristics of the great landslides have indicated the complicated relationship between the formation lithology and occurrence of the great landslides: on the one hand,the soft rock area is too weak to slide,on the other hand,the steep and high area dominated with hard rock often tend to slide.
Using the geologic record of the ancient dammed lake sediments for regional climate and environment characteristic is a kind of new way.It is different from through deep ocean,polar ice core,loess,lakes,stalagmites,coral etc sediments geological record study of global climate change.Many substitution indexes reflect the environmental information of sediments.Sediment granularity is one of these indexes.It can reflect the pale-environment and pale-climate characteristics in the sedimentary process.In the eastern edge of Qinghai-Tibet Plateau 20, 000 years,the climate-environment evolution and the geological environment evolution are established.The precise granularity analysis and systematic granularity analysis were used to extract the granularity information in the ancient dammed lake sediments,and glacial lake sediments with the existing research results were compared.Through the study,the following conclusions: Diexi ancient dammed lake sediments are semi-diagenetic(unconsolidated soil)materials,mostly composed of silt and clay grain sizes.Sedimentary bedding showed dark color and light colored alternating sedimentation features with rhythm-layer thickness between 2~5cm.Diexi ancient dammed lake sediments have different characteristics from loess and glacial lake sediments.Based on bed sizes and color,combined with organic tests,we found out that dark-colored coarse particles in the ancient dammed lake sediments were accumulated in an environment that has abundant rainfall and lush vegetation; while light-colored fine particles were accumulated in arid climate with relatively sparse vegetations.Systematic study of granularity on sediment profile showed that there were 7 cyclical changes in granularity,revealing 7 climate and environment changes the region experienced during the entire deposition process. Using the geologic record of the ancient dammed lake sediments for regional climate and environment characteristic is a kind of new way.It is different from through deep ocean,polar ice core,loess,lakes,stalagmites,coral etc sediments geological record study of global climate change.Many substitution indexes reflect the environmental information of sediments.Sediment granularity is one of these indexes.It can reflect the pale-environment and pale-climate characteristics in the sedimentary process.In the eastern edge of Qinghai-Tibet Plateau 20, 000 years,the climate-environment evolution and the geological environment evolution are established.The precise granularity analysis and systematic granularity analysis were used to extract the granularity information in the ancient dammed lake sediments,and glacial lake sediments with the existing research results were compared.Through the study,the following conclusions: Diexi ancient dammed lake sediments are semi-diagenetic(unconsolidated soil)materials,mostly composed of silt and clay grain sizes.Sedimentary bedding showed dark color and light colored alternating sedimentation features with rhythm-layer thickness between 2~5cm.Diexi ancient dammed lake sediments have different characteristics from loess and glacial lake sediments.Based on bed sizes and color,combined with organic tests,we found out that dark-colored coarse particles in the ancient dammed lake sediments were accumulated in an environment that has abundant rainfall and lush vegetation; while light-colored fine particles were accumulated in arid climate with relatively sparse vegetations.Systematic study of granularity on sediment profile showed that there were 7 cyclical changes in granularity,revealing 7 climate and environment changes the region experienced during the entire deposition process.
Based on experiment results,the creep propriety of Q3 loess with variation water content are analysed.As structural damage can decrease the strain modulus of loess,and the coupling action of creep laws of constitutive model of damage and rheology are also advanced.Being aware of the structural damage characteristic of loess,the rheological model of loess can reveal the natural deed of sudden destroy besides the advantage of less rheology parameter.In the paper,the pattern of model parameters changing with the water content of unsaturation loess are also studied as well as the methods that can decide the parameters of rheological model of loess are given by applying the rheology research results of structural soft soil.The result of numerical simulation shows that the constitutive model can describe loesss deformation characteristic well in the accelerated stage. Based on experiment results,the creep propriety of Q3 loess with variation water content are analysed.As structural damage can decrease the strain modulus of loess,and the coupling action of creep laws of constitutive model of damage and rheology are also advanced.Being aware of the structural damage characteristic of loess,the rheological model of loess can reveal the natural deed of sudden destroy besides the advantage of less rheology parameter.In the paper,the pattern of model parameters changing with the water content of unsaturation loess are also studied as well as the methods that can decide the parameters of rheological model of loess are given by applying the rheology research results of structural soft soil.The result of numerical simulation shows that the constitutive model can describe loesss deformation characteristic well in the accelerated stage.
We took aeolian sand as a kind of granular matter and studied its compaction characteristics in the view of guraular matter. According to the results of the laboratory compaction test,a compaction curve was plotted which was quite different from the clays and was similiar to double hump in shape. The two peaks in the curve meant that aeolian sand can be well-compacted whether it was dry or contented some water and water played different parts in the compaction process.and according to the results of vibrating compaction test,we can know that it was vibration acceleration and vibration time that affected the transform between Brazil-nut effects and anti-Brazil-nut effects,which also affected the compaction density. there were optimization values for both vibration acceleration and vibration time in that condition a optimized compaction density can be acquired. Also,field compaction tests were carride out(the amplitude of the machine was 0.4mm and the frequency was 48 Hertz). When the roadbed was compacted 5 times the degree of compaction was 96.8% and the value of CBR was 25.3 which were quite acceptable in the Specifications For Design Of Highway Subgrades. We took aeolian sand as a kind of granular matter and studied its compaction characteristics in the view of guraular matter. According to the results of the laboratory compaction test,a compaction curve was plotted which was quite different from the clays and was similiar to double hump in shape. The two peaks in the curve meant that aeolian sand can be well-compacted whether it was dry or contented some water and water played different parts in the compaction process.and according to the results of vibrating compaction test,we can know that it was vibration acceleration and vibration time that affected the transform between Brazil-nut effects and anti-Brazil-nut effects,which also affected the compaction density. there were optimization values for both vibration acceleration and vibration time in that condition a optimized compaction density can be acquired. Also,field compaction tests were carride out(the amplitude of the machine was 0.4mm and the frequency was 48 Hertz). When the roadbed was compacted 5 times the degree of compaction was 96.8% and the value of CBR was 25.3 which were quite acceptable in the Specifications For Design Of Highway Subgrades.
Cold nature of seasonal frozen soil engineering has great influence of temperature on moisture migration in order to understand the impact of the phenomenon,this paper tester temperature at different depths of field measurements of soil temperature and depth at different times to take the appropriate soil samples,measuring the water content. By comparing the different times the moisture content at different depths to analyze the changes in temperature on the moisture migration phenomenon. Rise in temperature before the local surface temperature is lowered,temperature the decrease with depth De increased; of the soil temperature is lower,the depth of the temperature Ye Department declining temperature gradient increased,the depth of the water formation rate changes Offices big,that the increase of the temperature gradient for the seasonal frozen soil moisture migration phenomenon. Cold nature of seasonal frozen soil engineering has great influence of temperature on moisture migration in order to understand the impact of the phenomenon,this paper tester temperature at different depths of field measurements of soil temperature and depth at different times to take the appropriate soil samples,measuring the water content. By comparing the different times the moisture content at different depths to analyze the changes in temperature on the moisture migration phenomenon. Rise in temperature before the local surface temperature is lowered,temperature the decrease with depth De increased; of the soil temperature is lower,the depth of the temperature Ye Department declining temperature gradient increased,the depth of the water formation rate changes Offices big,that the increase of the temperature gradient for the seasonal frozen soil moisture migration phenomenon.
Pore water pressures changing often reflect the degree of soil consolidation which using vacuum preloading method to deal with dredger fill.Drainage body was determined by measure drainage system under different pore water pressure on 6 test chambers.The results show that the soil pore water pressure drop in 0.4m was better than 0.8m,different drainage body had its own soil pore water.And the pore water pressure in the distance of 10cm to drainage body was half of the pore water pressure in drainage body.Membrane drain system was the best for drainage and then B-type drain system was better than sand drain system.In addition,in the dredger fill,the effective distance between drain pipes was between 0.4m and 0.8m.Moreover,membranes had large effective distance of drainage body,while B-types was the second and sand wells much smaller than the former two. Pore water pressures changing often reflect the degree of soil consolidation which using vacuum preloading method to deal with dredger fill.Drainage body was determined by measure drainage system under different pore water pressure on 6 test chambers.The results show that the soil pore water pressure drop in 0.4m was better than 0.8m,different drainage body had its own soil pore water.And the pore water pressure in the distance of 10cm to drainage body was half of the pore water pressure in drainage body.Membrane drain system was the best for drainage and then B-type drain system was better than sand drain system.In addition,in the dredger fill,the effective distance between drain pipes was between 0.4m and 0.8m.Moreover,membranes had large effective distance of drainage body,while B-types was the second and sand wells much smaller than the former two.
Connectivity rate of plastic zone is one of the most important criteria of the finite element method for evaluating stability of soil slope whether or not it reaches instability.The criterion,however,is not uniformly recognized at present.Therefore,a quantitative study emphatically on the criterion for evaluating stability of homogeneous soil slope is discussed in this paper.At first,Considering the three main parameters(cohesion force c、angle of internal friction 、slope ratio )of the slope stability,parameters of the slope which is in limiting state of equilibrium are selected by traditional slice method.Secondly,the connectivity rate of equivalent plastic strain median in shear band of the slope is got by adopting the above parameters.At last,the criteria formula(y=0.020702c+0.024417-0.67898+0.46799)for evaluating stability of slope is put forward though the multiple linear regression.The example indicates that the safety factor calculated by the formula is in accord with the Bishop slice method.So it validates that the quantitative criterion for evaluating stability of slope is reasonable. Connectivity rate of plastic zone is one of the most important criteria of the finite element method for evaluating stability of soil slope whether or not it reaches instability.The criterion,however,is not uniformly recognized at present.Therefore,a quantitative study emphatically on the criterion for evaluating stability of homogeneous soil slope is discussed in this paper.At first,Considering the three main parameters(cohesion force c、angle of internal friction 、slope ratio )of the slope stability,parameters of the slope which is in limiting state of equilibrium are selected by traditional slice method.Secondly,the connectivity rate of equivalent plastic strain median in shear band of the slope is got by adopting the above parameters.At last,the criteria formula(y=0.020702c+0.024417-0.67898+0.46799)for evaluating stability of slope is put forward though the multiple linear regression.The example indicates that the safety factor calculated by the formula is in accord with the Bishop slice method.So it validates that the quantitative criterion for evaluating stability of slope is reasonable.
Three dimensional nonlinear analyses on negative skin friction of a single pile was carried out for a specific case under surface loads. The results show the similarities and differences of negative skin friction behavior between friction pile and end-bearing pile. It was found that loading velocity of surface loads and the pile working loads influences negative skin friction very much: the more the loading velocity,the less the negative skin friction; the dragload of a pile without pile axial load is the ultimate value and could be considered as an upper limit for conventional analysis. Moreover,combinations of pile working load with surface load lead to change the pile axial force,namely,application of the working load and then application of the surface load caused a maximal negative skin friction,and on the contrary case minimum. Three dimensional nonlinear analyses on negative skin friction of a single pile was carried out for a specific case under surface loads. The results show the similarities and differences of negative skin friction behavior between friction pile and end-bearing pile. It was found that loading velocity of surface loads and the pile working loads influences negative skin friction very much: the more the loading velocity,the less the negative skin friction; the dragload of a pile without pile axial load is the ultimate value and could be considered as an upper limit for conventional analysis. Moreover,combinations of pile working load with surface load lead to change the pile axial force,namely,application of the working load and then application of the surface load caused a maximal negative skin friction,and on the contrary case minimum.
Grouting works are often executed under the geological environment of high formation pressure and high water pressure(such as warer shutoff or rock reinforcement in coal-mine).In order to study the flow characteristics of grouting slurry spreading under high pressure conditions,the author developed a grouting test system which can creat a high-pressure environment of over 5MPa.The test system consists of four functional modules,and can be divided into four equipment subsystems.The core equipment of the test system is the patent product Test Set-up for Simulating High Pressure Grouting,in which pressure transmission pipes are used as the solution to problems such as size effect,sensor corrosion-preventing and high-pressure sealing,which are encountered in designing the monitor program inside the high-pressure tank. Grouting works are often executed under the geological environment of high formation pressure and high water pressure(such as warer shutoff or rock reinforcement in coal-mine).In order to study the flow characteristics of grouting slurry spreading under high pressure conditions,the author developed a grouting test system which can creat a high-pressure environment of over 5MPa.The test system consists of four functional modules,and can be divided into four equipment subsystems.The core equipment of the test system is the patent product Test Set-up for Simulating High Pressure Grouting,in which pressure transmission pipes are used as the solution to problems such as size effect,sensor corrosion-preventing and high-pressure sealing,which are encountered in designing the monitor program inside the high-pressure tank.
It is very significant for engineering guide to study on earthquake ground motion parameter in high-fill project.According to the foundation parameter of some airport,the site modells of different filling thickness,different degree of compaction,different thickness of the original soil base is build up.Contrasting the research calculation result,the variety characteristic of the earthquake ground motion parameters of high-fill project under different site categories is acquired through actual data.The research result will provides valid parameter and science reasonable basis for the engineering design. It is very significant for engineering guide to study on earthquake ground motion parameter in high-fill project.According to the foundation parameter of some airport,the site modells of different filling thickness,different degree of compaction,different thickness of the original soil base is build up.Contrasting the research calculation result,the variety characteristic of the earthquake ground motion parameters of high-fill project under different site categories is acquired through actual data.The research result will provides valid parameter and science reasonable basis for the engineering design.
Useful explore researches had been done by experts on rock-classification for construction TBM tunnel,which were good idea for our later research.The current problem was no obvious consensus classification system or method for TBM tunnel,the classification parameters were more discrete and difficult to obtain,some quantitative indicators directly related to construction were not resolved.So,it was necessary to discuss detailly on rock-classification for construction hydraulic TBM tunnel.Based on the current tunnel rock classification of hydraulic methods from Geological Survey Water Resources and Hydropower Engineering Specification,refered to the Qinling Tunnel Rock Classification TBM construction method,an amended rock classification model was given to fit for hydraulic TBM tunnel,according to these amended parameters,such as,the efficiency,muck characteristics and water inflow of the TBM construction.Then the TBM tunnel construction Hydraulic Rock Classification was Achieved, 2 Examples were provided to validate the above method. Useful explore researches had been done by experts on rock-classification for construction TBM tunnel,which were good idea for our later research.The current problem was no obvious consensus classification system or method for TBM tunnel,the classification parameters were more discrete and difficult to obtain,some quantitative indicators directly related to construction were not resolved.So,it was necessary to discuss detailly on rock-classification for construction hydraulic TBM tunnel.Based on the current tunnel rock classification of hydraulic methods from Geological Survey Water Resources and Hydropower Engineering Specification,refered to the Qinling Tunnel Rock Classification TBM construction method,an amended rock classification model was given to fit for hydraulic TBM tunnel,according to these amended parameters,such as,the efficiency,muck characteristics and water inflow of the TBM construction.Then the TBM tunnel construction Hydraulic Rock Classification was Achieved, 2 Examples were provided to validate the above method.
A majority of the metro constructions in coastal area especially Guangzhou region are built in multi-strata ground. For this propose,a simplified geological model is proposed.With 3D-FEM,the influence of under-crossing construction on the displacement of the existing tunnel under different types of multi-strata ground,the thickness of the overlay soil and the distance of two tunnels is studied.The results show that when the new tunnel building in the homogeneous ground,the displacement is the maximum.The displacement for the case of upper-soft and lower-hard ground takes the second place.The displacement for the case of hard stratum is the minimum.The displacement of the existing tunnel decreases as the soil parameters increase.The displacement of the existing tunnel increases as the thickness of overlay soil increases and decreases as the net distance of two tunnels increases.When the net distance is less than 2 times of lining diameter,the displacement of the existing tunnel is great and the existing tunnel has risk of damage.Finally,corresponding measures are suggested to control the settlement effectively. A majority of the metro constructions in coastal area especially Guangzhou region are built in multi-strata ground. For this propose,a simplified geological model is proposed.With 3D-FEM,the influence of under-crossing construction on the displacement of the existing tunnel under different types of multi-strata ground,the thickness of the overlay soil and the distance of two tunnels is studied.The results show that when the new tunnel building in the homogeneous ground,the displacement is the maximum.The displacement for the case of upper-soft and lower-hard ground takes the second place.The displacement for the case of hard stratum is the minimum.The displacement of the existing tunnel decreases as the soil parameters increase.The displacement of the existing tunnel increases as the thickness of overlay soil increases and decreases as the net distance of two tunnels increases.When the net distance is less than 2 times of lining diameter,the displacement of the existing tunnel is great and the existing tunnel has risk of damage.Finally,corresponding measures are suggested to control the settlement effectively.
Five complete caverns were un-watered and discovered in Longyou in June 1992. They were manually caved in siltstone at shallow depths more than 2000 years ago. As time goes on,weathering of the surrounding rock of the caverns is increasing severely. The fact that the weathering degree of the surrounding rock nearby the entrance of the No.2 cavern is more serious than that inside the No.2 cavern are explained with the weathering difference of the pelitic siltstone due the difference in the micro-environments. The depths of the chisel marks of the surrounding rock nearby the entrance and inside the cavern No.2 were measured using plasticene. The corresponding curves of chisel mark depths were obtained. According to the measured results,the mean values of the maximum high recession and the maximum fluctuation ratio of the chisel marks inside the cavern is 10.2 mm and 0.43 respectively. The corresponding values of the chisel mark nearby the entrance are smaller. Their mean values are 8.0 mm and 0.35 respectively. The above values indicate that the weathering degree of chisel marks nearby the entrance are larger than that inside the cavern. It is believed that the above difference in the weathering degree is caused by different weathering micro-environments which mainly include rain,temperature,illumination intensity and lichen in the surrounding rock nearby the entrance and inside the cavern. Five complete caverns were un-watered and discovered in Longyou in June 1992. They were manually caved in siltstone at shallow depths more than 2000 years ago. As time goes on,weathering of the surrounding rock of the caverns is increasing severely. The fact that the weathering degree of the surrounding rock nearby the entrance of the No.2 cavern is more serious than that inside the No.2 cavern are explained with the weathering difference of the pelitic siltstone due the difference in the micro-environments. The depths of the chisel marks of the surrounding rock nearby the entrance and inside the cavern No.2 were measured using plasticene. The corresponding curves of chisel mark depths were obtained. According to the measured results,the mean values of the maximum high recession and the maximum fluctuation ratio of the chisel marks inside the cavern is 10.2 mm and 0.43 respectively. The corresponding values of the chisel mark nearby the entrance are smaller. Their mean values are 8.0 mm and 0.35 respectively. The above values indicate that the weathering degree of chisel marks nearby the entrance are larger than that inside the cavern. It is believed that the above difference in the weathering degree is caused by different weathering micro-environments which mainly include rain,temperature,illumination intensity and lichen in the surrounding rock nearby the entrance and inside the cavern.
Due to the complexity of engineering geological conditions and particularity of tunnel projects in Fuzhou Basin,the corresponding environmental geotechnical problems are emerged in the process of construction for Fuzhou rail transit. The main environmental geotechnical engineering problems are: (1)the confined aquifer within the scope of tunneling boring: The water-bearing capacity and hydraulic conductivity of confined aquifer are strong. As the excavation is deep,the influences on lower confined water must be considered,so that inrush of foundation pit may be avoided. The gravel pebble bed is directly covered on the hot water of bedrock fissure,and it is directly supplied and conducted by high-temperature hot water at the hot water structural belt. The issues,whether the construction of underground rail transit brings impact on geothermal field and what influence does geothermy bring to rail transit,need to be further studied.(2)Large deformation and low intensity of soft soils lead to instability of foundation and damage of the soil structure strength.(3)Deep and large excavation for foundation pit may cause the disasters. The excavation for foundation pit is easy to bring the problems,such as slump,mudflow,water inrush,surface subsidence,etc. ,so the effective preventive measures should be adopted to avoid the impact on engineering safety and surrounding environment. For these environmental geotechnical problems,new technologies for investigation shall be strengthened to find out geological conditions of the geotechnical engineering at building site; the ground freezing method and technology of pile underpinning shall be introduced for the construction; the new technologies,which are suitable for geotechnical conditions in the region,shall be developed and adopted,such as new piles,new water-seal,ground-water lowering measures and other foundation pit support technologies as well as new technology for information construction. Due to the complexity of engineering geological conditions and particularity of tunnel projects in Fuzhou Basin,the corresponding environmental geotechnical problems are emerged in the process of construction for Fuzhou rail transit. The main environmental geotechnical engineering problems are: (1)the confined aquifer within the scope of tunneling boring: The water-bearing capacity and hydraulic conductivity of confined aquifer are strong. As the excavation is deep,the influences on lower confined water must be considered,so that inrush of foundation pit may be avoided. The gravel pebble bed is directly covered on the hot water of bedrock fissure,and it is directly supplied and conducted by high-temperature hot water at the hot water structural belt. The issues,whether the construction of underground rail transit brings impact on geothermal field and what influence does geothermy bring to rail transit,need to be further studied.(2)Large deformation and low intensity of soft soils lead to instability of foundation and damage of the soil structure strength.(3)Deep and large excavation for foundation pit may cause the disasters. The excavation for foundation pit is easy to bring the problems,such as slump,mudflow,water inrush,surface subsidence,etc. ,so the effective preventive measures should be adopted to avoid the impact on engineering safety and surrounding environment. For these environmental geotechnical problems,new technologies for investigation shall be strengthened to find out geological conditions of the geotechnical engineering at building site; the ground freezing method and technology of pile underpinning shall be introduced for the construction; the new technologies,which are suitable for geotechnical conditions in the region,shall be developed and adopted,such as new piles,new water-seal,ground-water lowering measures and other foundation pit support technologies as well as new technology for information construction.
Based on the Biot theory and friction contact theory,a FEM model including wake effect of pipeline-soil interaction is developed to investigate the wave induced response of pipeline and seabed soil.The effect of wake to the stability of pipeline laid on seabed is analyzed,and a set of stability graph applicable to different engineering geologic regions in Chengdao area are proposed based on the numerical results. Based on the Biot theory and friction contact theory,a FEM model including wake effect of pipeline-soil interaction is developed to investigate the wave induced response of pipeline and seabed soil.The effect of wake to the stability of pipeline laid on seabed is analyzed,and a set of stability graph applicable to different engineering geologic regions in Chengdao area are proposed based on the numerical results.
Loess in China is distributed in the seasonal frozen soil area.Effect of Freezing-thawing has greatly influenced on the stability of loess slope which has special structure,impel a large number of loess hazards.Study on Freezing-thawing mechanism,has some important theoretical and practical significance to reduce loess slope hazards.According to the characters of loess slope and Freezing-thawing,use numerical simulation of the surface freezing temperature,analysis groundwater accumulation model before and after freezing,and analysis example,reveal freezing process on surface soil of slope and water accumulation,discuss the Freezing effect on slope surface and response on stability.The result is: (1)The Freezing effect begin from surface to inner,reach maximum depth about 3 months after the freezing; (2)Analysis the simple groundwater accumulation model,derive the equation of groundwater saturation line; (3)The stability of loess slope will reduce about 25% by the effect of freezing-thawing. Loess in China is distributed in the seasonal frozen soil area.Effect of Freezing-thawing has greatly influenced on the stability of loess slope which has special structure,impel a large number of loess hazards.Study on Freezing-thawing mechanism,has some important theoretical and practical significance to reduce loess slope hazards.According to the characters of loess slope and Freezing-thawing,use numerical simulation of the surface freezing temperature,analysis groundwater accumulation model before and after freezing,and analysis example,reveal freezing process on surface soil of slope and water accumulation,discuss the Freezing effect on slope surface and response on stability.The result is: (1)The Freezing effect begin from surface to inner,reach maximum depth about 3 months after the freezing; (2)Analysis the simple groundwater accumulation model,derive the equation of groundwater saturation line; (3)The stability of loess slope will reduce about 25% by the effect of freezing-thawing.
Xiaowan hydropower station locates in the mountain-gorge region,the geodynamical process of the deep-incised river valley decides its present morphological characteristics,rock mass structure and stability,and deeply effects slope design plan and selection of dam base surface.Based on field investigation and experimental analysis,these main conclusions are formed as follows: (1)The exogenetic reconstruction of deep-incised valley slope is very strong because of unloading and weathering effect,and a great number of middle-gentle fissures are generated,the SN high dip angle fissures near slope surface are propagated and gapping; and a great number of EW compressed zone(surface)generated near the slope surface.(2)the generation mechanism of middle-gentle fissures includes propagation of old joint and new generation,the middle-gentle fissures in river valley bottom are further propagated because of differential unloading rebound,and when rock mass quality in the upper slope is stepwise lowering and so earth stresses are stepwise adjusted,the middle-gentle fissures are propagated because of shear slide,the river valley slope stepwise enter time-effect deformation period; (3)The geo-engineering classification of river valley slope is proposed,the potential deformation failure modes of each classification are topping failure,plane slide,steplike slide,wedge failure and accumulation body faiure etc. Xiaowan hydropower station locates in the mountain-gorge region,the geodynamical process of the deep-incised river valley decides its present morphological characteristics,rock mass structure and stability,and deeply effects slope design plan and selection of dam base surface.Based on field investigation and experimental analysis,these main conclusions are formed as follows: (1)The exogenetic reconstruction of deep-incised valley slope is very strong because of unloading and weathering effect,and a great number of middle-gentle fissures are generated,the SN high dip angle fissures near slope surface are propagated and gapping; and a great number of EW compressed zone(surface)generated near the slope surface.(2)the generation mechanism of middle-gentle fissures includes propagation of old joint and new generation,the middle-gentle fissures in river valley bottom are further propagated because of differential unloading rebound,and when rock mass quality in the upper slope is stepwise lowering and so earth stresses are stepwise adjusted,the middle-gentle fissures are propagated because of shear slide,the river valley slope stepwise enter time-effect deformation period; (3)The geo-engineering classification of river valley slope is proposed,the potential deformation failure modes of each classification are topping failure,plane slide,steplike slide,wedge failure and accumulation body faiure etc.
During the construction of great amount of metros and tunnels,more engineering geological problems have emerged.Based on the particular geological conditions in Shanghai area,this paper analyzed the engineering geological condition related to the construction of metro and tunnel projects,which includes structure character of engineering geological stratum and groundwater level situation of shallow aquifers.Then this paper studied the major engineering geological problems induced during the construction,and some division maps of engineering geological problem grade have been made out,which can be the guidance for project design and construction. During the construction of great amount of metros and tunnels,more engineering geological problems have emerged.Based on the particular geological conditions in Shanghai area,this paper analyzed the engineering geological condition related to the construction of metro and tunnel projects,which includes structure character of engineering geological stratum and groundwater level situation of shallow aquifers.Then this paper studied the major engineering geological problems induced during the construction,and some division maps of engineering geological problem grade have been made out,which can be the guidance for project design and construction.
It was named as Sanjiang(which mean Nu River,Lancang River and Jinsha River in English)Sector on YunnanTibet railway east from Lijiang city in Yunnan province and west to Basu county in Tibet Autonomous region,and it was conformed the Sanjiang sector was the most difficult sector on railway construction,especially there exited complex engineering geological problems.By the authors recent-year study,some new understandings on fundamental geology were put forward,thus recognitions on the possible railway engineering geological problems were fundamentally rooted out.The strata or rock distributed extensively in Sanjiang region were Paleozoic limestone like islands surrounded by Mesozoic sandy mudstone,and then the late Yanshan period magmatite was developed there.The connection between earthquake and active fault was not very close,and there were no obvious regional fault signs.It was comprehensively realized there existed many deep-level railway engineering geological problems in Sanjiang sector including the problem caused by karstification in limestone areas,the problem caused by soluble salts precipitation in clastic rocks areas,the problem in drop-style slide rockmasses,the problem caused by earthquake,the problem in high geothermal temperature areas and the problem caused by cleavable zone.Each type of the problems were corelated.The sub sectors with serious problems were the sector from Lashi lake in Yulong county to Hutiao town street in Sangrila county,Baima Snow Mountain sector in Deqin county,Meili Snow Mountain sector in Deqin county and Lengqu sector in Basu county,which should be deeply researched and treated by countermeasures. It was named as Sanjiang(which mean Nu River,Lancang River and Jinsha River in English)Sector on YunnanTibet railway east from Lijiang city in Yunnan province and west to Basu county in Tibet Autonomous region,and it was conformed the Sanjiang sector was the most difficult sector on railway construction,especially there exited complex engineering geological problems.By the authors recent-year study,some new understandings on fundamental geology were put forward,thus recognitions on the possible railway engineering geological problems were fundamentally rooted out.The strata or rock distributed extensively in Sanjiang region were Paleozoic limestone like islands surrounded by Mesozoic sandy mudstone,and then the late Yanshan period magmatite was developed there.The connection between earthquake and active fault was not very close,and there were no obvious regional fault signs.It was comprehensively realized there existed many deep-level railway engineering geological problems in Sanjiang sector including the problem caused by karstification in limestone areas,the problem caused by soluble salts precipitation in clastic rocks areas,the problem in drop-style slide rockmasses,the problem caused by earthquake,the problem in high geothermal temperature areas and the problem caused by cleavable zone.Each type of the problems were corelated.The sub sectors with serious problems were the sector from Lashi lake in Yulong county to Hutiao town street in Sangrila county,Baima Snow Mountain sector in Deqin county,Meili Snow Mountain sector in Deqin county and Lengqu sector in Basu county,which should be deeply researched and treated by countermeasures.
A number of green schist rocks developed on the right abutment of Jinping I Hydropower Station.They are one of the important engineering geology problems for the stability of abutment.In order to study their trace length distribution,the technique of 3D laser scanning was applied.The zone of green schist outcrop was scanned with it.The elevation of scanned zone ranged form 1720 to 1670m,and fall is up to 50m,scanned area 3500m2.After the interpretation of points cloud for these green schist rocks,resulting trace length data were attained accurately,which provided the possibility to study the trace length distribution of green schist rocks.Based on study,it was found that trace length data mainly were grouped to the zone of 0 to 3m.With the growth of trace length,the number of trace length was getting less and less in every subinterval; in the range from 0 to 9m,samples showed Normal Distribution in every subinterval.As for all of samples,the trace length showed Logarithmic Normal Distribution. A number of green schist rocks developed on the right abutment of Jinping I Hydropower Station.They are one of the important engineering geology problems for the stability of abutment.In order to study their trace length distribution,the technique of 3D laser scanning was applied.The zone of green schist outcrop was scanned with it.The elevation of scanned zone ranged form 1720 to 1670m,and fall is up to 50m,scanned area 3500m2.After the interpretation of points cloud for these green schist rocks,resulting trace length data were attained accurately,which provided the possibility to study the trace length distribution of green schist rocks.Based on study,it was found that trace length data mainly were grouped to the zone of 0 to 3m.With the growth of trace length,the number of trace length was getting less and less in every subinterval; in the range from 0 to 9m,samples showed Normal Distribution in every subinterval.As for all of samples,the trace length showed Logarithmic Normal Distribution.
The NSFC proposals and grants of engineering geology in 2010 were analyzed.The amount of proposals increases fast.The competitiveness of the proposals has yet to be improved.The distribution of researchers in fundamental studies is not balanced among the different institutions.Concentration ratio of research capability increases among the different institutions.The age distribution of the applicant tends to be reasonable.There are no obvious differences of funded ratio between different age group. The NSFC proposals and grants of engineering geology in 2010 were analyzed.The amount of proposals increases fast.The competitiveness of the proposals has yet to be improved.The distribution of researchers in fundamental studies is not balanced among the different institutions.Concentration ratio of research capability increases among the different institutions.The age distribution of the applicant tends to be reasonable.There are no obvious differences of funded ratio between different age group.
2010, 18(5): 803-803.
Abstract(2351)
326KB(1281)