2014 Vol. 22, No. 4

论文
2014, 22(4): 0-0.
Abstract(2070)
320KB(722)
This paper discussed the influence of the bound water on the consolidation and creep behavior of saturated soft soil using the method combined the macroscopic mechanical behavior with quantitative analysis of the microstructure. First, measurement techniques such as SEM, mercury injection and the maximum amount of water absorption were applied to test the pore grading of the soft soil under different load levels, and the variation of the microstructure in the consolidation deformation process of the silt soil was quantitatively analyzed. It is found that a gradual loose of structural strength and discharge of different types of pore water occur in this process. The free water and bound water in the pore of the soft soil were divided. Then, the high pressure consolidation test reveals that there are two distinct phases during the consolidation process. The former is mainly concerned with the free water, whereas the latter has a close relationship with the behavior of the bound water. The correlation between the coefficient of viscosity and the thickness of water film in the soft soil was analyzed based on the creep test. This paper discussed the influence of the bound water on the consolidation and creep behavior of saturated soft soil using the method combined the macroscopic mechanical behavior with quantitative analysis of the microstructure. First, measurement techniques such as SEM, mercury injection and the maximum amount of water absorption were applied to test the pore grading of the soft soil under different load levels, and the variation of the microstructure in the consolidation deformation process of the silt soil was quantitatively analyzed. It is found that a gradual loose of structural strength and discharge of different types of pore water occur in this process. The free water and bound water in the pore of the soft soil were divided. Then, the high pressure consolidation test reveals that there are two distinct phases during the consolidation process. The former is mainly concerned with the free water, whereas the latter has a close relationship with the behavior of the bound water. The correlation between the coefficient of viscosity and the thickness of water film in the soft soil was analyzed based on the creep test.
Academician Gu Dezhen was a well-known engineering geologist,also Chinese engineering geological founder. He was well-regarded,excellence academic,modes,sincere and had the spirit of courage to bear. He had shown the utmost solicitude,and had paid more attention to the training and teaching,and is an example for young people. He was the director of the 1st engineering geological professional committee of the Geological Society of China. Under his leadership,the engineering geology had been developing rapidly. Especially,he founded the rock mass structure control theory,which promoted the development of Chinese engineering geology in 20 Century. This theory had made some important contributions to the development of engineering and construction in China. Rock mass structure control theory had grown into a big tree,had formed many branches,such as the rock mass structure classification,rock mass structure mechanics,engineering geological mechanics,inverse analysis method,et al. Nanjing University preferred plane group have studied his structure control theory,and had proposed the preferred plane theory for the efforts of 30 years. A new research method and direction of the preferred plane theory have been formed,and is a branch of structural control theory. In the 21 century,on base of the academic though of the structure control theory,the internal relationship between nature laws to macro and more micro laws for engineering geology will be explored by the methods of nano-geology and nanotechnology. Researchers should pay attention to the problem of disasters chain,the disaster types and disaster mechanism in the study of prevention and prediction of geological disasters,and give countermeasures of controlling geological disasters. At the same time,the research of information systems of decision,management and prevention of disaster should be strengthened. This year is the 100 anniversary of the birth of Academician Gu Dezhen. Writing this paper will offer the feeling of our thoughts and admiration to Academician Gu Dezhen. Academician Gu Dezhen was a well-known engineering geologist,also Chinese engineering geological founder. He was well-regarded,excellence academic,modes,sincere and had the spirit of courage to bear. He had shown the utmost solicitude,and had paid more attention to the training and teaching,and is an example for young people. He was the director of the 1st engineering geological professional committee of the Geological Society of China. Under his leadership,the engineering geology had been developing rapidly. Especially,he founded the rock mass structure control theory,which promoted the development of Chinese engineering geology in 20 Century. This theory had made some important contributions to the development of engineering and construction in China. Rock mass structure control theory had grown into a big tree,had formed many branches,such as the rock mass structure classification,rock mass structure mechanics,engineering geological mechanics,inverse analysis method,et al. Nanjing University preferred plane group have studied his structure control theory,and had proposed the preferred plane theory for the efforts of 30 years. A new research method and direction of the preferred plane theory have been formed,and is a branch of structural control theory. In the 21 century,on base of the academic though of the structure control theory,the internal relationship between nature laws to macro and more micro laws for engineering geology will be explored by the methods of nano-geology and nanotechnology. Researchers should pay attention to the problem of disasters chain,the disaster types and disaster mechanism in the study of prevention and prediction of geological disasters,and give countermeasures of controlling geological disasters. At the same time,the research of information systems of decision,management and prevention of disaster should be strengthened. This year is the 100 anniversary of the birth of Academician Gu Dezhen. Writing this paper will offer the feeling of our thoughts and admiration to Academician Gu Dezhen.
With the continuous advance of engineering geomechanics and its related disciplines as well as unceasing resolution of relevant problems,the engineering geomechanics is now entering into a new development stage. This paper summarizes brilliant achievements and great challenges for this discipline in the 20th century and then presents its theoretical system in detail including structure relativity of engineering geological mass,continuity of engineering geological mass,constitutive relation of engineering geological mass,large deformation of engineering geological mass and large-deformation design method of engineer geological mass, et al. At last,great prospects for engineering geomechanics have been proposed in many aspects such as research of material control in large deformation disaster,engineering disaster control,energy constitutive relations of engineering geological mass,energy equilibrium equation of engineering geological mass and trend of quantitative design in geological engineering. Basing on all of discussions,we should be aware that the task of engineering geomechanics workers has far to go. With the continuous advance of engineering geomechanics and its related disciplines as well as unceasing resolution of relevant problems,the engineering geomechanics is now entering into a new development stage. This paper summarizes brilliant achievements and great challenges for this discipline in the 20th century and then presents its theoretical system in detail including structure relativity of engineering geological mass,continuity of engineering geological mass,constitutive relation of engineering geological mass,large deformation of engineering geological mass and large-deformation design method of engineer geological mass, et al. At last,great prospects for engineering geomechanics have been proposed in many aspects such as research of material control in large deformation disaster,engineering disaster control,energy constitutive relations of engineering geological mass,energy equilibrium equation of engineering geological mass and trend of quantitative design in geological engineering. Basing on all of discussions,we should be aware that the task of engineering geomechanics workers has far to go.
Daguangbao landslide with an area of 7.12km2 and a volume of 1.159 billion m3 is the largest landslide triggered by the Wenchuan MS8.0 Earthquake occurred on May 12th,2008,and also is the largest one in China and one of the few giant landslides more than one billion m3 in the world. It is located in the hanging wall of the seismogenic fault of the Wenchuan earthquake,and 3.0~4.5km away from it. The authors' team has conducted a engineering geological survey including mapping,geophysical exploration,pitting and boreholes with a scale of 1:2000 since 2011. According to the data,we finished a series of geological maps including a comprehensive plane map and 25 sections. The spatial shape of the landslide,pre- and post-failure structures,slip surface and its characteristics were further investigated and a set of quantitative data about Daguangbao landslide features was obtained. We found it was a hugewedge failure with a strike slipping sliding along a bedded shear fault. According to the description of witnesses and structures of the accumulation,we rebuilt the experience of the slope failure and sliding process during the strong quaking. Basically,it can be divided into five stages:shattering-tensile cracking,cutting through of the front locking section,suddenly braking and napping motion,detaching sliding on both sides of the accumulation and finally secondary sliding of the scarp cliff. The accumulation can be divided into three area and ten sub-areas. They are the main scarp area,the accumulation area,and the back depression area,which corresponding to three,four and three sub-areas respectively. Daguangbao landslide with an area of 7.12km2 and a volume of 1.159 billion m3 is the largest landslide triggered by the Wenchuan MS8.0 Earthquake occurred on May 12th,2008,and also is the largest one in China and one of the few giant landslides more than one billion m3 in the world. It is located in the hanging wall of the seismogenic fault of the Wenchuan earthquake,and 3.0~4.5km away from it. The authors' team has conducted a engineering geological survey including mapping,geophysical exploration,pitting and boreholes with a scale of 1:2000 since 2011. According to the data,we finished a series of geological maps including a comprehensive plane map and 25 sections. The spatial shape of the landslide,pre- and post-failure structures,slip surface and its characteristics were further investigated and a set of quantitative data about Daguangbao landslide features was obtained. We found it was a hugewedge failure with a strike slipping sliding along a bedded shear fault. According to the description of witnesses and structures of the accumulation,we rebuilt the experience of the slope failure and sliding process during the strong quaking. Basically,it can be divided into five stages:shattering-tensile cracking,cutting through of the front locking section,suddenly braking and napping motion,detaching sliding on both sides of the accumulation and finally secondary sliding of the scarp cliff. The accumulation can be divided into three area and ten sub-areas. They are the main scarp area,the accumulation area,and the back depression area,which corresponding to three,four and three sub-areas respectively.
The origin,development and problem of seismic force analysis methods for slope stability are described in this paper. The codes of seismic analysis for the stabilization of slopes and landslides based on pseudo-static analysis were compared,and then some questions such as the magnified effect and coefficient of acceleration distributions,the rigid and non-rigid of landslides models,and the static and dynamic analysis were discussed. Pseudo-static analysis is one of the commonly used methods put forward firstly by Terzaghi K. However,it was questioned by scholars including Terzaghi himself from the start. Since Seed H.B.study systematically on the damage of earth-rock fill dam triggered by San Fernando earthquake on February 9,1971,the time-depended dynamic analysis has made significant progress and became the more scientific and logical method in Europe and America. The method in the Building Codes in Earthquake Region of the former Soviet Union in the 1940-1950s and the Chinese Specifications for Seismic Design of Hydraulic Structures(SDJ10-78)enacted in the 70s were still being used in the landslides codes formulated and revised after the Wenchuan earthquake,and the design theories and practical application are still at the primary experience stage. The authors suggest that new theory and methods should be recommended for reference to promote the modernized and standardized management of landslide seismic force analysis in China. That is,as the stability evaluation of landslide under the gravity should be classified to circle slice method and broken-line method according to the characteristics of rock and soil,the stability analysis of slopes under seismic load should be classified too:(1)for rockslides,pseudo-static analysis with amplification factor of earthquake inertia force distributed along the height should be preferred; (2)for saturated homogenous soil landslide,dynamics analytical method considering liquefaction feature under cyclic loading should be preferred; (3)for rock-soil accumulation landslides,pseudo-static or dynamic analysis methods with simplified amplification factor are generally to be preferred according to the landslides conditions. The origin,development and problem of seismic force analysis methods for slope stability are described in this paper. The codes of seismic analysis for the stabilization of slopes and landslides based on pseudo-static analysis were compared,and then some questions such as the magnified effect and coefficient of acceleration distributions,the rigid and non-rigid of landslides models,and the static and dynamic analysis were discussed. Pseudo-static analysis is one of the commonly used methods put forward firstly by Terzaghi K. However,it was questioned by scholars including Terzaghi himself from the start. Since Seed H.B.study systematically on the damage of earth-rock fill dam triggered by San Fernando earthquake on February 9,1971,the time-depended dynamic analysis has made significant progress and became the more scientific and logical method in Europe and America. The method in the Building Codes in Earthquake Region of the former Soviet Union in the 1940-1950s and the Chinese Specifications for Seismic Design of Hydraulic Structures(SDJ10-78)enacted in the 70s were still being used in the landslides codes formulated and revised after the Wenchuan earthquake,and the design theories and practical application are still at the primary experience stage. The authors suggest that new theory and methods should be recommended for reference to promote the modernized and standardized management of landslide seismic force analysis in China. That is,as the stability evaluation of landslide under the gravity should be classified to circle slice method and broken-line method according to the characteristics of rock and soil,the stability analysis of slopes under seismic load should be classified too:(1)for rockslides,pseudo-static analysis with amplification factor of earthquake inertia force distributed along the height should be preferred; (2)for saturated homogenous soil landslide,dynamics analytical method considering liquefaction feature under cyclic loading should be preferred; (3)for rock-soil accumulation landslides,pseudo-static or dynamic analysis methods with simplified amplification factor are generally to be preferred according to the landslides conditions.
Engineering Geo-mechanics of Rock Mass founded by professor Gu Dezhen last century has been one of representative scientific theories of engineering geology in China. The core of the theory is the mechanical effect of rock mass structure. The paper firstly summarizes the principles of Gu Dezhen's theory, and then introduces the exploration and progress during the past 20 years on Statistic Mechanics of Rock Mass (SMRM) which has been a development of Gu's thought. The achievements of SMRM mainly include the parameterized statistical model of rock mass structure, stress-strain relationship, strength and failure probability, and hydraulic model of rock mass. Various of mechanic and hydraulic effects and controlling regulations of rock mass structure reflected by these quantitative models have been discussed. The concept of initiative reinforcement to make use of the self-stabilization potential of rock mass and a mode of anchorage emphasizing the enhancement the slope foot have been proposed in the paper. It is pointed out that Gu's theory, Engineering Geo-mechanics of Rock Mass, has strong vitality because it revealed the basic law of the behavior of rock mass and the dominant factors of it. To promote the quantitative development of Gu's theory is a historical task of the followers. Engineering Geo-mechanics of Rock Mass founded by professor Gu Dezhen last century has been one of representative scientific theories of engineering geology in China. The core of the theory is the mechanical effect of rock mass structure. The paper firstly summarizes the principles of Gu Dezhen's theory, and then introduces the exploration and progress during the past 20 years on Statistic Mechanics of Rock Mass (SMRM) which has been a development of Gu's thought. The achievements of SMRM mainly include the parameterized statistical model of rock mass structure, stress-strain relationship, strength and failure probability, and hydraulic model of rock mass. Various of mechanic and hydraulic effects and controlling regulations of rock mass structure reflected by these quantitative models have been discussed. The concept of initiative reinforcement to make use of the self-stabilization potential of rock mass and a mode of anchorage emphasizing the enhancement the slope foot have been proposed in the paper. It is pointed out that Gu's theory, Engineering Geo-mechanics of Rock Mass, has strong vitality because it revealed the basic law of the behavior of rock mass and the dominant factors of it. To promote the quantitative development of Gu's theory is a historical task of the followers.
Based on Deere and Miller's classification of rock,the soft rock can be classified into two kinds,namely plastic and weakly elastic. Accordingly this paper presents two types of compression extrusion,i.e.,fully plastic and plastic-semi elastic. Differential equations were established to calculate deformation of extrusion. Formulas were then derived from these equations to estimate the minimum thickness of the strata for occurrence of compression extrusion,thickness of the strata for compression deformation and failure,stress distribution within the surrounding rock near the tunnel face,volume of extruded rocks and length of extruded rocks. The conditions for extrusion and their relationship with physical and mechanical parameters of rock as well as their variations were analyzed using those formulas. The estimated minimum thicknesses of overlying strata for several tunnels match closely with the observed data,which proves the applicability of presented method in engineering practices. Based on Deere and Miller's classification of rock,the soft rock can be classified into two kinds,namely plastic and weakly elastic. Accordingly this paper presents two types of compression extrusion,i.e.,fully plastic and plastic-semi elastic. Differential equations were established to calculate deformation of extrusion. Formulas were then derived from these equations to estimate the minimum thickness of the strata for occurrence of compression extrusion,thickness of the strata for compression deformation and failure,stress distribution within the surrounding rock near the tunnel face,volume of extruded rocks and length of extruded rocks. The conditions for extrusion and their relationship with physical and mechanical parameters of rock as well as their variations were analyzed using those formulas. The estimated minimum thicknesses of overlying strata for several tunnels match closely with the observed data,which proves the applicability of presented method in engineering practices.
Rock mass structure theory was a major theoretical innovation of the 20th century in Chinese engineering geology academia. In this paper,a brief introduction to the theory which has been widely applied in China since the 1970s has been done. The theory provides a theoretical basis and method to guide the resolution of major engineering geology problems encountered in a series of world-class engineering construction. From part of cases study,the rock mass structure theory,vigorously promoted by the authorities as industry standards,is revealed the scope of its successful application,including rock-mass stability evaluation,rock mass quality,rock slope failure mechanism and selection of foundation rock mass in a large-scale hydropower. Moreover,this paper discusses the acquisition method of main indexes about rock mass differences,quantitative indicators and aspects of its improvement. On the basis of the above study,two new sub-class rock structure,i.e.,in situ mosaic-fragmented structure and bond-layer structure,is proposed. Then their typical characteristics,disaggregated index as well as those effective applications in practical engineering are illustrated. Rock mass structure theory was a major theoretical innovation of the 20th century in Chinese engineering geology academia. In this paper,a brief introduction to the theory which has been widely applied in China since the 1970s has been done. The theory provides a theoretical basis and method to guide the resolution of major engineering geology problems encountered in a series of world-class engineering construction. From part of cases study,the rock mass structure theory,vigorously promoted by the authorities as industry standards,is revealed the scope of its successful application,including rock-mass stability evaluation,rock mass quality,rock slope failure mechanism and selection of foundation rock mass in a large-scale hydropower. Moreover,this paper discusses the acquisition method of main indexes about rock mass differences,quantitative indicators and aspects of its improvement. On the basis of the above study,two new sub-class rock structure,i.e.,in situ mosaic-fragmented structure and bond-layer structure,is proposed. Then their typical characteristics,disaggregated index as well as those effective applications in practical engineering are illustrated.
Based on the derived general expression for the displacement of a point in a surrounding rock mass caused by excavating under the action of self-weight volume forces from similarity theory,by means of dimensional analysis,and comparing with the results of the numeral simulations,an empirical formula of parametric ratios expressed in geometric,physical and mechanical parameters is proposed,which shows the quantitative relationships between the displacement of a point in a surrounding rock mass caused by excavating in a linearly elastic semi-infinite body and any one of the parameters,including the specific weight of a rock material,the modulus of elasticity for the material,the size of a cross section of a tunnel and the distance from the earth surface to the center of the cross section. And the conditions under which the formula holds and its applications are discussed, and the methods for use it are given. A main conclusion says that,in the case that the geometric similarity law is not completely satisfied,under the given other conditions the displacement of a point in the rock mass surrounding a tunnel is proportional to the product of the distance from the center of cross section to the earth surface and the size of the cross section and is independent of the shape of the cross section. Based on the derived general expression for the displacement of a point in a surrounding rock mass caused by excavating under the action of self-weight volume forces from similarity theory,by means of dimensional analysis,and comparing with the results of the numeral simulations,an empirical formula of parametric ratios expressed in geometric,physical and mechanical parameters is proposed,which shows the quantitative relationships between the displacement of a point in a surrounding rock mass caused by excavating in a linearly elastic semi-infinite body and any one of the parameters,including the specific weight of a rock material,the modulus of elasticity for the material,the size of a cross section of a tunnel and the distance from the earth surface to the center of the cross section. And the conditions under which the formula holds and its applications are discussed, and the methods for use it are given. A main conclusion says that,in the case that the geometric similarity law is not completely satisfied,under the given other conditions the displacement of a point in the rock mass surrounding a tunnel is proportional to the product of the distance from the center of cross section to the earth surface and the size of the cross section and is independent of the shape of the cross section.
Beijing as capital of China is located in North China. The geothermal field in Beijing is mainly medium-low temperature conductive type,in which the Wumishan Formation with a thickness of more than 2000m of the Jixian System is the main reservoir and the rock of the Wumishan Formation is dolomite. Conductivity of the reservoir was usually calculated to understand reservoir characteristics,which could not accurately reflect permeability of the reservoir due to density variation of geothermal water. In order to understand permeability of the reservoir to direct geothermal resources development,porosity and permeability data of 34 dolomite rock cores collected from field outcrop and down-hole were compared and analyzed. The results indicated that permeability of outcrop and down-hole ranges are (10.0001158~0.33333)10-3m2 and (0.0088~0.334)10-3m2 respectively,and the average value are 0.062232110-3m2 and 0.38531610-3m2. The porosity ranges from 0.25%to 3.00%. The permeability of the rock cores are so low that geothermal energy could not be exacted without factures and fissures generated from tectonic movement and karstification. Therefore,permeability calculated from pump test could reflect total permeability of rock matrix,fractures and fissures. The calculated permeability of reservoir from 110 pump tests ranges from 13.7410-3m2 to 104474.0010-3m2,and the average is 4797.5810-3m2. The cumulated percentage of permeability values between 10010-3m2 and 100010-3m2 are more than 75%,the values less than 10010-3m2 are only 13.64%,and the permeability values greater than 10000010-3m2 are 0.91 percent. In order to demonstrate relationship between reservoir buried depth and permeability,the buried depth were divided into 500m,500~1000m,1000~1500m,1500~2000m,2000~2500m,2500~3000m and 3000~3500m. The average permeability and average buried depth were plotted together in x,y coordinates. The results indicated that the average permeability of geothermal reservoir decays in the way of exponential with the increasing of reservoir buried depth,and R2 is 0.9415,indicating good correlation. The relationship between reservoir buried depth and permeability is significant in assessing potential of Wumishan Formation reservoir,calculating geothermal well depth accurately before drilling and reducing geological risks in Beijing. Beijing as capital of China is located in North China. The geothermal field in Beijing is mainly medium-low temperature conductive type,in which the Wumishan Formation with a thickness of more than 2000m of the Jixian System is the main reservoir and the rock of the Wumishan Formation is dolomite. Conductivity of the reservoir was usually calculated to understand reservoir characteristics,which could not accurately reflect permeability of the reservoir due to density variation of geothermal water. In order to understand permeability of the reservoir to direct geothermal resources development,porosity and permeability data of 34 dolomite rock cores collected from field outcrop and down-hole were compared and analyzed. The results indicated that permeability of outcrop and down-hole ranges are (10.0001158~0.33333)10-3m2 and (0.0088~0.334)10-3m2 respectively,and the average value are 0.062232110-3m2 and 0.38531610-3m2. The porosity ranges from 0.25%to 3.00%. The permeability of the rock cores are so low that geothermal energy could not be exacted without factures and fissures generated from tectonic movement and karstification. Therefore,permeability calculated from pump test could reflect total permeability of rock matrix,fractures and fissures. The calculated permeability of reservoir from 110 pump tests ranges from 13.7410-3m2 to 104474.0010-3m2,and the average is 4797.5810-3m2. The cumulated percentage of permeability values between 10010-3m2 and 100010-3m2 are more than 75%,the values less than 10010-3m2 are only 13.64%,and the permeability values greater than 10000010-3m2 are 0.91 percent. In order to demonstrate relationship between reservoir buried depth and permeability,the buried depth were divided into 500m,500~1000m,1000~1500m,1500~2000m,2000~2500m,2500~3000m and 3000~3500m. The average permeability and average buried depth were plotted together in x,y coordinates. The results indicated that the average permeability of geothermal reservoir decays in the way of exponential with the increasing of reservoir buried depth,and R2 is 0.9415,indicating good correlation. The relationship between reservoir buried depth and permeability is significant in assessing potential of Wumishan Formation reservoir,calculating geothermal well depth accurately before drilling and reducing geological risks in Beijing.
Tension and shear fracture form of rock is under special stress state,that is under the normal tension stress perpendicular to the failure surface and shear stress parallel to rupture surface. Using the self-developed DSC-800 rock tension and shear apparatus with electro-hydraulic servo,we conducted plenty of tension and shear tests of granodiorite and sandstone; carried out corresponding three-dimensional laser scan of fracture surface,SEM,rock physical and mechanical properties tests,PFC numerical modeling tests,etal. Then studied the features of rock tension and shear fracture surface using fractal theory; got the whole fracture criterion of rock from tension-shear area to compression-shear area; analyzed the influences of rate of shear to rock tension and shear strength; studied the process of rock failure under tension and shear using PFC.Research conclusions are as follow:(1)Macro and micro fractal dimension(roughness) of the fracture surface increase with the increase of tension stress.(2)Micro fracture pattern of rock is combination of tension fracture and shear fracture. Micro fracture pattern is mainly about shear failure when tension stress is small; the tension failure is distinct gradually as tension stress increases.(3)Tension stress and shear stress have linear negative relationship in tension shear area. Line slope in tension shear area is greater than that in compression shear zone,and rock is more easy to fracture in tension shear area.(4)Under the condition of tension and shear,shear rate and shear strength have nonlinear inverse relationship. With the increase of shear rate,roughness of rock tension shear fracture surface increases.(5)Establish PFC numerical test model of rock under tension and shear stress to simulate force chain evolution in the process of rock fracture and the influence of shear rate on the roughness of tension shear fracture surface,and get the same results as laboratory tests. Tension and shear fracture form of rock is under special stress state,that is under the normal tension stress perpendicular to the failure surface and shear stress parallel to rupture surface. Using the self-developed DSC-800 rock tension and shear apparatus with electro-hydraulic servo,we conducted plenty of tension and shear tests of granodiorite and sandstone; carried out corresponding three-dimensional laser scan of fracture surface,SEM,rock physical and mechanical properties tests,PFC numerical modeling tests,etal. Then studied the features of rock tension and shear fracture surface using fractal theory; got the whole fracture criterion of rock from tension-shear area to compression-shear area; analyzed the influences of rate of shear to rock tension and shear strength; studied the process of rock failure under tension and shear using PFC.Research conclusions are as follow:(1)Macro and micro fractal dimension(roughness) of the fracture surface increase with the increase of tension stress.(2)Micro fracture pattern of rock is combination of tension fracture and shear fracture. Micro fracture pattern is mainly about shear failure when tension stress is small; the tension failure is distinct gradually as tension stress increases.(3)Tension stress and shear stress have linear negative relationship in tension shear area. Line slope in tension shear area is greater than that in compression shear zone,and rock is more easy to fracture in tension shear area.(4)Under the condition of tension and shear,shear rate and shear strength have nonlinear inverse relationship. With the increase of shear rate,roughness of rock tension shear fracture surface increases.(5)Establish PFC numerical test model of rock under tension and shear stress to simulate force chain evolution in the process of rock fracture and the influence of shear rate on the roughness of tension shear fracture surface,and get the same results as laboratory tests.
Apply Mr. Gu Dezhen's theory of engineering geomechanics of rock mass. Attach great importance to regional geological tectonic system, collection of geological initial information and research of rock mass structure. Then carry out engineering geological investigation of the high arch dam, high gravity dam, deep buried long tunnel, underground powerhouse, pumped storage power station, and write the corresponding geological survey standard. Apply Mr. Gu Dezhen's theory of engineering geomechanics of rock mass. Attach great importance to regional geological tectonic system, collection of geological initial information and research of rock mass structure. Then carry out engineering geological investigation of the high arch dam, high gravity dam, deep buried long tunnel, underground powerhouse, pumped storage power station, and write the corresponding geological survey standard.
In recent years, Chinese railway construction technology has improved significantly. Number and length of tunnel engineering increase considerably and the engineering geological conditions are more complicated. Along with the significant technical progress, some major design changes and injuries also occurred in the construction process. During technology survey, the authors started with analyzing regional engineering geological conditions. Based on studying the usual geological factors, such as fracture structure, fold structure, rock strength, rock mass integrity, karst and special soil, apply petrology, mineralogy, structural geology and rock structural mechanics, etc. to deepen understanding some special engineering geological factors. Authors confirm that high in-situ stress squeezing action, extremely soft rock extruding and unloading effect, ancient metamorphic soft interlayer sliding action, dike (wall) body softening and bedding shearing deformation are the main geological factors to cause surrounding rock instability and collapse during tunnel construction. Due to understanding insufficiently and lack of the corresponding engineering measures before, it caused significant adverse impact to construction, investment and time limit for a project. Combing with 11 engineering examples, the paper analyses five types of surrounding rock deformation characteristics and causes and put forwards engineering countermeasures. Expect to draw lessons and reduce similar problems. In recent years, Chinese railway construction technology has improved significantly. Number and length of tunnel engineering increase considerably and the engineering geological conditions are more complicated. Along with the significant technical progress, some major design changes and injuries also occurred in the construction process. During technology survey, the authors started with analyzing regional engineering geological conditions. Based on studying the usual geological factors, such as fracture structure, fold structure, rock strength, rock mass integrity, karst and special soil, apply petrology, mineralogy, structural geology and rock structural mechanics, etc. to deepen understanding some special engineering geological factors. Authors confirm that high in-situ stress squeezing action, extremely soft rock extruding and unloading effect, ancient metamorphic soft interlayer sliding action, dike (wall) body softening and bedding shearing deformation are the main geological factors to cause surrounding rock instability and collapse during tunnel construction. Due to understanding insufficiently and lack of the corresponding engineering measures before, it caused significant adverse impact to construction, investment and time limit for a project. Combing with 11 engineering examples, the paper analyses five types of surrounding rock deformation characteristics and causes and put forwards engineering countermeasures. Expect to draw lessons and reduce similar problems.
Loess Plateau is one of the birthplaces of the Chinese nation. It is also the youngest plateau and has been rising ceaselessly in our world. Besides,it had been recorded the information of global change in detail during the Pleistocene epoch,especially in the aspects of climate changes and geological hazards. According to the statistics of geological hazards in China,there are almost one third of cases in this area. These geological hazards caused great loss of life and properties. Hence,the mitigation of geological hazards in Loess Plateau is urgent and necessary. This paper summarizes geological hazards in Loess Plateau. Moreover,according to the results of previous research and engineering geological investigation,the critical issues and creative concepts,such as the couple analysis of soil mechanics and engineering geology,triggering and evolution mechanism,early warning system and so on,are suggested to mitigate the geological hazards in loess area. Loess Plateau is one of the birthplaces of the Chinese nation. It is also the youngest plateau and has been rising ceaselessly in our world. Besides,it had been recorded the information of global change in detail during the Pleistocene epoch,especially in the aspects of climate changes and geological hazards. According to the statistics of geological hazards in China,there are almost one third of cases in this area. These geological hazards caused great loss of life and properties. Hence,the mitigation of geological hazards in Loess Plateau is urgent and necessary. This paper summarizes geological hazards in Loess Plateau. Moreover,according to the results of previous research and engineering geological investigation,the critical issues and creative concepts,such as the couple analysis of soil mechanics and engineering geology,triggering and evolution mechanism,early warning system and so on,are suggested to mitigate the geological hazards in loess area.
During the construction of expressway tunnel in Karst area,the geological structure near the tunnel line should be known,especially whether Karst and fractured zone develop or not,which have important influence on the safety of tunnel construction. In the geophysical exploration work on bad geologic body of deep-long tunnel,Controlled Source Audio Frequency Magnetotellurics Method(CSAMT) is fairly effective one. In this paper,we compared the original sounding curve near the borehole with the electrical resistivity of the borehole samples,to check the reliability of the data. Combination with geological interpretation and verification,the results show that CSAMT method has a good effect in exploring the geological structure of tunnel in Karst area,and has a certain guiding significance for tunnel construction. During the construction of expressway tunnel in Karst area,the geological structure near the tunnel line should be known,especially whether Karst and fractured zone develop or not,which have important influence on the safety of tunnel construction. In the geophysical exploration work on bad geologic body of deep-long tunnel,Controlled Source Audio Frequency Magnetotellurics Method(CSAMT) is fairly effective one. In this paper,we compared the original sounding curve near the borehole with the electrical resistivity of the borehole samples,to check the reliability of the data. Combination with geological interpretation and verification,the results show that CSAMT method has a good effect in exploring the geological structure of tunnel in Karst area,and has a certain guiding significance for tunnel construction.
Reservoir project of the Chushandian was get downed in 1958a, Because of lacking research for problem on the properties change under engineering condition. After 10a, Gezhouba construction project also met with similar problem. Macro and micro reasearch results show the mudzation seam of claystone is caused by interbedding shear failure of rock structure. For this reason, the claystone in dam foundation is stable. Reservoir project of the Chushandian was get downed in 1958a, Because of lacking research for problem on the properties change under engineering condition. After 10a, Gezhouba construction project also met with similar problem. Macro and micro reasearch results show the mudzation seam of claystone is caused by interbedding shear failure of rock structure. For this reason, the claystone in dam foundation is stable.
China,a mountainous country in Asia,is rich in mountain tourism resources. Buddhist Mountains like Emei Mountain,Wuyue(Mount tai and other four Mountains),and other famous scenic mountains like Huangshan have attracted numerous visitors every year. At the same time,affected by the frequently occurred mountain geological hazards,many of these tourist attractions have become high-risk areas. Therefore,a sound tourism planning which has taken full consideration of the mountain hazards is of particular significance to the success of mountain tourism development. However,current tourism planning for mountain areas contains few considerations of mountain hazards prevention and treatment,and thus incapable to manage the safety risks faced by tourists. For this reason,we proposed the conception of mountain tourism planning served engineering geology-a interdiscipline of tourism planning and engineering geology-for the purpose of ensuring tourists safety and constructing tourism safety guarantee system in mountain resorts,and hence promoting the sustainable development of mountain tourism industry. Moreover,this interdisciplinary research identifies a new research area of engineering geology. China,a mountainous country in Asia,is rich in mountain tourism resources. Buddhist Mountains like Emei Mountain,Wuyue(Mount tai and other four Mountains),and other famous scenic mountains like Huangshan have attracted numerous visitors every year. At the same time,affected by the frequently occurred mountain geological hazards,many of these tourist attractions have become high-risk areas. Therefore,a sound tourism planning which has taken full consideration of the mountain hazards is of particular significance to the success of mountain tourism development. However,current tourism planning for mountain areas contains few considerations of mountain hazards prevention and treatment,and thus incapable to manage the safety risks faced by tourists. For this reason,we proposed the conception of mountain tourism planning served engineering geology-a interdiscipline of tourism planning and engineering geology-for the purpose of ensuring tourists safety and constructing tourism safety guarantee system in mountain resorts,and hence promoting the sustainable development of mountain tourism industry. Moreover,this interdisciplinary research identifies a new research area of engineering geology.
On the basis of consulting treatises of Mr. Gu Dezhen before his death,it is discovered that he not only is a wellknown scholar of engineering geology at home and abroad,but is a development scholar of research of engineering earthquake in China. He started to follow with interest the earthquake problems in engineering construction since the engineering of harnessing Huai river as early as 1951,and specially focused on the problems of engineering earthquake since the Xinfengjiang reservoir induced earthquake at 1959. He presented the scientifically thins and technical methods on evaluation of earthquake safety in engineering area. He presented new conception on active fault,and suggested to call all the active fracture since late pleistocence as active fault. He also put forward that identification active fault start from regional tectonic development history. He presented the scientifically point on genetic mechanism of reservoir induced earthquake,which combined effect of water loading, strong weakening and pore pressure caused by water infliction along fault zone. Mr. Gu applied above points,thinks and methods successfully to a series of great engineering practices,for example harnessing of Xinfengjiang reservoir induced earthquake,dam site selection and investigation of Gezhouba and Danjiangkou reservoir, etc. On the basis of consulting treatises of Mr. Gu Dezhen before his death,it is discovered that he not only is a wellknown scholar of engineering geology at home and abroad,but is a development scholar of research of engineering earthquake in China. He started to follow with interest the earthquake problems in engineering construction since the engineering of harnessing Huai river as early as 1951,and specially focused on the problems of engineering earthquake since the Xinfengjiang reservoir induced earthquake at 1959. He presented the scientifically thins and technical methods on evaluation of earthquake safety in engineering area. He presented new conception on active fault,and suggested to call all the active fracture since late pleistocence as active fault. He also put forward that identification active fault start from regional tectonic development history. He presented the scientifically point on genetic mechanism of reservoir induced earthquake,which combined effect of water loading, strong weakening and pore pressure caused by water infliction along fault zone. Mr. Gu applied above points,thinks and methods successfully to a series of great engineering practices,for example harnessing of Xinfengjiang reservoir induced earthquake,dam site selection and investigation of Gezhouba and Danjiangkou reservoir, etc.
Taking the engineering geological investigation and exploration of rocky foundation soil and design and construction of foundation structure of Wuhan Changjiang River Great Bridge completed under professor Gu's lead and guidence for an example,this paper presents specifically and vividly that the first and the most important one among Mr. Gu's academic thoughts is attaching great importance to practice. To put in a nutshell,this thought plays great attention to investigation and exploration of engineering geology during the earlier stage of an engineering project. Then further verify and correct the achivements in the earlier work,closely combine the work with geotechnical engineering and,finally ensure safe and economical completion of those engineering projects,geological engineering project for the purpose of control and presentation of geological disasters and/or the specifical geotechnical engineering project. Taking the engineering geological investigation and exploration of rocky foundation soil and design and construction of foundation structure of Wuhan Changjiang River Great Bridge completed under professor Gu's lead and guidence for an example,this paper presents specifically and vividly that the first and the most important one among Mr. Gu's academic thoughts is attaching great importance to practice. To put in a nutshell,this thought plays great attention to investigation and exploration of engineering geology during the earlier stage of an engineering project. Then further verify and correct the achivements in the earlier work,closely combine the work with geotechnical engineering and,finally ensure safe and economical completion of those engineering projects,geological engineering project for the purpose of control and presentation of geological disasters and/or the specifical geotechnical engineering project.
Evaluation of the structure and stability of Zhangmu Deposit means a lot to Zhangmu Port, the only international overland trading port between China and Nepal, which is located on it and has faced the threat of geological disasters over a long time. To demonstrate the stability of the slope, the engineering geological structure and soil-rock mixture types of Zhangmu Deposit along with the slope deformation and failure laws are preliminary analyzed based on the field survery. Results show that, Zhangmu Deposit is composed of not just one single soil structure, but includes colluvial, residual and glaciofluvial deposits amongst others, and the slope less likely slides as a whole, but will mainly slip partially controlled by the terrain and human engineering activities. Evaluation of the structure and stability of Zhangmu Deposit means a lot to Zhangmu Port, the only international overland trading port between China and Nepal, which is located on it and has faced the threat of geological disasters over a long time. To demonstrate the stability of the slope, the engineering geological structure and soil-rock mixture types of Zhangmu Deposit along with the slope deformation and failure laws are preliminary analyzed based on the field survery. Results show that, Zhangmu Deposit is composed of not just one single soil structure, but includes colluvial, residual and glaciofluvial deposits amongst others, and the slope less likely slides as a whole, but will mainly slip partially controlled by the terrain and human engineering activities.
It reflects a typical divergent thinking process again from the theory of rock mass structure controlling to theMeta-Synthetic Analysis Methodology,and its essence is to seize principal contradiction and take into account the existence of many influential factors. It is a very specific and practical work for engineering geologists to better understand and evaluate the suitability,controllability of factors,engineering adjustability and other problems of the sites in different conditions,in the case that land resources become increasingly tense while our large scale scientific facility sites are restricted by many factors. The authors proposed the Dynamic Controlling Concept of the geological engineering based on One Rock,One Concept and One Method,in the evaluation processes of the Daya Bay neutrino experiments tunnel,China spallation neutron source site and seven other large scientific facility sites. Therefore,engineers can adjust the project layout timely and propose the transformation of the boundaries of the site and intensity of construction-related proposals to achieve a harmonious and reasonable regulation of geological engineering under the premise of concentrating on controlling structural elements,delineating adverse geological bodies. It reflects a typical divergent thinking process again from the theory of rock mass structure controlling to theMeta-Synthetic Analysis Methodology,and its essence is to seize principal contradiction and take into account the existence of many influential factors. It is a very specific and practical work for engineering geologists to better understand and evaluate the suitability,controllability of factors,engineering adjustability and other problems of the sites in different conditions,in the case that land resources become increasingly tense while our large scale scientific facility sites are restricted by many factors. The authors proposed the Dynamic Controlling Concept of the geological engineering based on One Rock,One Concept and One Method,in the evaluation processes of the Daya Bay neutrino experiments tunnel,China spallation neutron source site and seven other large scientific facility sites. Therefore,engineers can adjust the project layout timely and propose the transformation of the boundaries of the site and intensity of construction-related proposals to achieve a harmonious and reasonable regulation of geological engineering under the premise of concentrating on controlling structural elements,delineating adverse geological bodies.
About 35 years ago,Professor TAN Tjong-Kie proposed the hypothesis of rock locked in stresses and considered the locked in stresses were the failure cause of rock engineering projects. In recent years,Professor Wang Sijing and Professor Qian Qihu have made some qualitative discussions on the hypothesis. However,this hypothesis has received very little attention and quantitative investigation. In this paper,the author puts forward and attempts to show that the tiny gas(or liquid) inclusions in contact rocks are a specific,concrete and measurable type of variable and considerable locked in stresses and kinetic energy. The pressure and volumetric expansion energy of a gas inclusion are a type of locked in(or sealed) stresses and internal deformation energy of actual existence and active power. The author gives the governing equations to calculate the pressure and volumetric expansion energy of gas inclusions,which is shown with calculation examples. The pressure of the gas inclusions is equivalent to the average value of the in-situ stresses in deep rocks. The gas inclusions,sealed in micro-defects or voids of deep rocks,are the common tensile or expanding volumetric force sources for the occurrences of many failures in the surrounding rocks of excavated or engineered caverns or tunnels in deep rock ground. Because of differences in the physical and mechanical properties of the surrounding rocks,the compressed and dense gas inclusions can cause the following three results and/or phenomena. They are (a) stable walls,(b) brittle fractures and (c) large deformation of the surrounding rocks. Hard and brittle intact rocks can have brittle fractures in the forms of rock burst,mine earthquake,rock split,and zonal disintegration. Soft and ductile intact rocks can have the deformation failure in the forms large deformation,creep and pressure bump accordingly. In addition,the gas inclusions with high pressure can be the source of abnormally high in-situ stresses in some special deep rock grounds. About 35 years ago,Professor TAN Tjong-Kie proposed the hypothesis of rock locked in stresses and considered the locked in stresses were the failure cause of rock engineering projects. In recent years,Professor Wang Sijing and Professor Qian Qihu have made some qualitative discussions on the hypothesis. However,this hypothesis has received very little attention and quantitative investigation. In this paper,the author puts forward and attempts to show that the tiny gas(or liquid) inclusions in contact rocks are a specific,concrete and measurable type of variable and considerable locked in stresses and kinetic energy. The pressure and volumetric expansion energy of a gas inclusion are a type of locked in(or sealed) stresses and internal deformation energy of actual existence and active power. The author gives the governing equations to calculate the pressure and volumetric expansion energy of gas inclusions,which is shown with calculation examples. The pressure of the gas inclusions is equivalent to the average value of the in-situ stresses in deep rocks. The gas inclusions,sealed in micro-defects or voids of deep rocks,are the common tensile or expanding volumetric force sources for the occurrences of many failures in the surrounding rocks of excavated or engineered caverns or tunnels in deep rock ground. Because of differences in the physical and mechanical properties of the surrounding rocks,the compressed and dense gas inclusions can cause the following three results and/or phenomena. They are (a) stable walls,(b) brittle fractures and (c) large deformation of the surrounding rocks. Hard and brittle intact rocks can have brittle fractures in the forms of rock burst,mine earthquake,rock split,and zonal disintegration. Soft and ductile intact rocks can have the deformation failure in the forms large deformation,creep and pressure bump accordingly. In addition,the gas inclusions with high pressure can be the source of abnormally high in-situ stresses in some special deep rock grounds.
Multi-level mining in the Jinchuan No.2mine had attracted extensive research interests. In particular,rock mass deformation and catastrophe was the most prominent one. In this study,surface monitoring results proved that no evident mutation or abnormal events occurred from the beginning to end of the underground mining in the levels 1250 and 1150m. In addition,displacement boundary conditions should be adopted in excavation mechanical model rather than the force boundary conditions because the strain energy is a constant and the excavation activities should be considered as an energy transfer and dissipation process in the model. The small scale mining and filling techniques are helpful to avoid large magnitude rock mass movement,thus,the surrounding rock mass did not occur catastrophic instability but exhibit loose and break features in the mining. Finally,it indicated that the displacement rates of the ground rock mass are mainly associated with the mining rate and filling quality. Thus,the catastrophe phenomenon of ground rock mass movement and deformation will not happen if these two factors remain the same in the future. Multi-level mining in the Jinchuan No.2mine had attracted extensive research interests. In particular,rock mass deformation and catastrophe was the most prominent one. In this study,surface monitoring results proved that no evident mutation or abnormal events occurred from the beginning to end of the underground mining in the levels 1250 and 1150m. In addition,displacement boundary conditions should be adopted in excavation mechanical model rather than the force boundary conditions because the strain energy is a constant and the excavation activities should be considered as an energy transfer and dissipation process in the model. The small scale mining and filling techniques are helpful to avoid large magnitude rock mass movement,thus,the surrounding rock mass did not occur catastrophic instability but exhibit loose and break features in the mining. Finally,it indicated that the displacement rates of the ground rock mass are mainly associated with the mining rate and filling quality. Thus,the catastrophe phenomenon of ground rock mass movement and deformation will not happen if these two factors remain the same in the future.
The tomography velocity of compress and shear seismic wave is related with the mechanic parameters of rock and soil. The dispersion curves of the multi channel analysis of surface wave method(MASW)can be gotten from the common middle points cross correlation(CMPCC)gather which is processed as same as the reflection seismic method. We can get the 2D velocity structure from inversing dispersion cures in whole profile,it is well applied in the layering rock and soil strata. The elastic mechanics parameters,such as elastic module and poisson ratio, etc can be deduced by comparing the refraction tomography velocity with surface wave veolocity in the same profile,to supply the useful information in the next engineering geology exploration and design,rock and soil mechanics experiment in the laboratory as well. The tomography velocity of compress and shear seismic wave is related with the mechanic parameters of rock and soil. The dispersion curves of the multi channel analysis of surface wave method(MASW)can be gotten from the common middle points cross correlation(CMPCC)gather which is processed as same as the reflection seismic method. We can get the 2D velocity structure from inversing dispersion cures in whole profile,it is well applied in the layering rock and soil strata. The elastic mechanics parameters,such as elastic module and poisson ratio, etc can be deduced by comparing the refraction tomography velocity with surface wave veolocity in the same profile,to supply the useful information in the next engineering geology exploration and design,rock and soil mechanics experiment in the laboratory as well.
Changyudongtian World Geological Park,an ancient underground quarry cavern group,is located at Wenling City,Zhejiang Province. Based on the field investigation,the quarry were excavated by the ancients,which can be traced back to 1500 years ago,in a hill with the coverage of 16 square kilometers. Among of 28 large underground cavern groups in the underground quarry,Lingxiao cavern group is one typical example,with the height and span more than 55m and 28m respectively,for its main cavern. To clarify the reasons of long-term stability of these ancient caverns,the authors have carried out the study on the engineering geological conditions of the caverns,taking Lingxiao cavern group as an example. The achievements also accumulate the important geological documents for the protection of Changyudongtian ancient underground cavern groups and the safety guarantee of the tourists. Changyudongtian World Geological Park,an ancient underground quarry cavern group,is located at Wenling City,Zhejiang Province. Based on the field investigation,the quarry were excavated by the ancients,which can be traced back to 1500 years ago,in a hill with the coverage of 16 square kilometers. Among of 28 large underground cavern groups in the underground quarry,Lingxiao cavern group is one typical example,with the height and span more than 55m and 28m respectively,for its main cavern. To clarify the reasons of long-term stability of these ancient caverns,the authors have carried out the study on the engineering geological conditions of the caverns,taking Lingxiao cavern group as an example. The achievements also accumulate the important geological documents for the protection of Changyudongtian ancient underground cavern groups and the safety guarantee of the tourists.