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Editor Work1996 Vol. 4, No. 1
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Abstract
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Sandaogou Landslide is the on-bank (front) part of a large ancient landslide located in the new urban aera of Badong County. First cracks appeared in June, 1995, and progressively developed for 4 months. Then the ground failed and the lanslide took place on 29th of Oct. With a volume of 200, 000 m3. Thanks to correct prediction and in time mitigation measures taken by the local government, the damages caused by this slide were reduced to minimum.The principal factors for the ground deformation and slide are the steep relief on the front of the ancient landslide, very loose landslide deposits with low strength,and river erosion of the southern bank associated with narrowing of the river channel caused by accumulation of fluvial sediments on the opposite bank at Zhajiaoji on the Yangtze River. The triggering factors are rainfall, fluctuating water level, artificial waste loads on the slope from new urban area, dynamic loads, and changing hydrogeological conditions, which resulted in further lowering of mechanical strength of the ground mass and hence led the slope being in a critical state to fail.
Sandaogou Landslide is the on-bank (front) part of a large ancient landslide located in the new urban aera of Badong County. First cracks appeared in June, 1995, and progressively developed for 4 months. Then the ground failed and the lanslide took place on 29th of Oct. With a volume of 200, 000 m3. Thanks to correct prediction and in time mitigation measures taken by the local government, the damages caused by this slide were reduced to minimum.The principal factors for the ground deformation and slide are the steep relief on the front of the ancient landslide, very loose landslide deposits with low strength,and river erosion of the southern bank associated with narrowing of the river channel caused by accumulation of fluvial sediments on the opposite bank at Zhajiaoji on the Yangtze River. The triggering factors are rainfall, fluctuating water level, artificial waste loads on the slope from new urban area, dynamic loads, and changing hydrogeological conditions, which resulted in further lowering of mechanical strength of the ground mass and hence led the slope being in a critical state to fail.
1996, 4(1): 8-13.
In the process of 3-D net work Modelling of discontinuities, the size of discontinuities is an important parameter. This parameter is mainly come from measuring the trace length in-situ. Sampling errors can occur due to the bias, these errors need to be corrected for the estimation of mean trace length. The method introduced here takes sampling errors into account by probability theory and through the traces data from finite 2D window transfor to trace length in infinite 2-D space. By means of computer, it is easy to estimate the mean trace legnth.
In the process of 3-D net work Modelling of discontinuities, the size of discontinuities is an important parameter. This parameter is mainly come from measuring the trace length in-situ. Sampling errors can occur due to the bias, these errors need to be corrected for the estimation of mean trace length. The method introduced here takes sampling errors into account by probability theory and through the traces data from finite 2D window transfor to trace length in infinite 2-D space. By means of computer, it is easy to estimate the mean trace legnth.
1996, 4(1): 14-19.
In this paper, the authors reasonably determine the hydraulic silting periods on the basis of hydraulic test results and making good use of the method of sublevel mud pressure to calculate the maximum silting height, in order toprovide scientific basis for reasonable budget of the time linit and capital expenditure of the hydraulic silting engineering of tens kilometer long Liufangti.
In this paper, the authors reasonably determine the hydraulic silting periods on the basis of hydraulic test results and making good use of the method of sublevel mud pressure to calculate the maximum silting height, in order toprovide scientific basis for reasonable budget of the time linit and capital expenditure of the hydraulic silting engineering of tens kilometer long Liufangti.
1996, 4(1): 20-26.
This paper deals with the problems of quantitative predication of location of interbed shear zone in perpenticular direction findings in theory. In the beginning, the mechanism is studied further and new classification is proposed; The concept of scale is introduced; The exteral and interal factors effecting on the location of shear zoner and how to take them into consideration are discussed. Then, two models are developed to quantitatively describe the charactertics of alternate hard-soft layersand to predict the position of shear zones within different elements. Finally, a systematic methodiology on the quantitative prediction of loaction of shear zones in the perpendicular direction is proposed. It was used in predicition of shear zones in Gao BaZhuo dam site.
This paper deals with the problems of quantitative predication of location of interbed shear zone in perpenticular direction findings in theory. In the beginning, the mechanism is studied further and new classification is proposed; The concept of scale is introduced; The exteral and interal factors effecting on the location of shear zoner and how to take them into consideration are discussed. Then, two models are developed to quantitatively describe the charactertics of alternate hard-soft layersand to predict the position of shear zones within different elements. Finally, a systematic methodiology on the quantitative prediction of loaction of shear zones in the perpendicular direction is proposed. It was used in predicition of shear zones in Gao BaZhuo dam site.
1996, 4(1): 27-31.
Cohesive soil contains much free ferric oxide, especially in laterite. The engineering geological properties of cohesive soil(laterite) are influenced by free ferric oxide content in it. In this paper, the author studys this problems by experiment. The main result is as follows:(1) Cohesive strength of cohesive soil (laterite) increased with increasing of free ferric oxide content. The cohesive force(C)and friction angle () are correlated with free ferric oxide content (FC). The correlation factor between C and FC is 0.78,and between and FC is 0.72. The compaction dry unit weight decreased with increasing free ferric oxide content (r=0.94). The relation between free expansion ratio and FC is negative correlation (r=0. 83). (2) The relations between plastic limit (Wp) and shrinkage limit (Ws) with FC are direct correlation (Wp-FC:r= 0. 901 Ws-FC:r=0.88).(3)The correlations between shrinkage ratio(Es) and shrinkage index (Is )wkh FC are not clear, but with increasing FC, their general trend is to reducte. (4)The liquid limit(WL) and plastic index (Ip ) are not correlated with FC (WL-FC: r=0.34 IP -FC: r=0.51). If making a concrete analysis of each group of soil samples,the result is not alike. Perphs the different form of free ferric oxide leads to this abnormal phenomena.
Cohesive soil contains much free ferric oxide, especially in laterite. The engineering geological properties of cohesive soil(laterite) are influenced by free ferric oxide content in it. In this paper, the author studys this problems by experiment. The main result is as follows:(1) Cohesive strength of cohesive soil (laterite) increased with increasing of free ferric oxide content. The cohesive force(C)and friction angle () are correlated with free ferric oxide content (FC). The correlation factor between C and FC is 0.78,and between and FC is 0.72. The compaction dry unit weight decreased with increasing free ferric oxide content (r=0.94). The relation between free expansion ratio and FC is negative correlation (r=0. 83). (2) The relations between plastic limit (Wp) and shrinkage limit (Ws) with FC are direct correlation (Wp-FC:r= 0. 901 Ws-FC:r=0.88).(3)The correlations between shrinkage ratio(Es) and shrinkage index (Is )wkh FC are not clear, but with increasing FC, their general trend is to reducte. (4)The liquid limit(WL) and plastic index (Ip ) are not correlated with FC (WL-FC: r=0.34 IP -FC: r=0.51). If making a concrete analysis of each group of soil samples,the result is not alike. Perphs the different form of free ferric oxide leads to this abnormal phenomena.
1996, 4(1): 32-38.
In this paper the stability of clayey seabottom in the continental shelf area of South China Sea in the Pearl River Mouth and in the Xiangshan Bay of the East Sea are analyzed. The causes of the instabilities are revealed. Diagrams for estimation of the stability are given. Finally, the direction of further investigation is pointed out.
In this paper the stability of clayey seabottom in the continental shelf area of South China Sea in the Pearl River Mouth and in the Xiangshan Bay of the East Sea are analyzed. The causes of the instabilities are revealed. Diagrams for estimation of the stability are given. Finally, the direction of further investigation is pointed out.
1996, 4(1): 39-44.
The developmental history of the research microstructure of clayey soil is outlined,the recent study situation and problems in our country are analysed, and tendency of the research is discussed in this paper.
The developmental history of the research microstructure of clayey soil is outlined,the recent study situation and problems in our country are analysed, and tendency of the research is discussed in this paper.
1996, 4(1): 45-52.
The portland cement as a consolidating agent for increasing the strength of Soft cohesive ground and decreasing its deformation, already is widespread used in construction in the coastal area. Usually using dry powder mixing methed or deep bed stirring method for mixing portland cement into soft cohesive ground and reacting physico-chemically, we can get reinforce effect.This research project is supported by Jiangsu Province Science and Technology Foundation (Grant No. 91246). A comparative test for the cement soil samples in laboratory and in-situ, and macroscopic and microscopic analizes made us to the mechanism of reinforcing the soft cohesive ground with portland cement. A proposal on increasing the strength of soft cohesive ground, and economizing portland cement is putted forward.
The portland cement as a consolidating agent for increasing the strength of Soft cohesive ground and decreasing its deformation, already is widespread used in construction in the coastal area. Usually using dry powder mixing methed or deep bed stirring method for mixing portland cement into soft cohesive ground and reacting physico-chemically, we can get reinforce effect.This research project is supported by Jiangsu Province Science and Technology Foundation (Grant No. 91246). A comparative test for the cement soil samples in laboratory and in-situ, and macroscopic and microscopic analizes made us to the mechanism of reinforcing the soft cohesive ground with portland cement. A proposal on increasing the strength of soft cohesive ground, and economizing portland cement is putted forward.
1996, 4(1): 53-59.
This paper sets forth the possibility to evaluate the seismic liquefaction poetntial with shear wave velocity. Comparative analysis has been made about the evaluating methods of seismic liquefaction potential with shear wave velocity at home and abroad.It is indicated that the formula (b) which is used to evaluate seismic liquefaction poetential in this paper is practical and reliable.
This paper sets forth the possibility to evaluate the seismic liquefaction poetntial with shear wave velocity. Comparative analysis has been made about the evaluating methods of seismic liquefaction potential with shear wave velocity at home and abroad.It is indicated that the formula (b) which is used to evaluate seismic liquefaction poetential in this paper is practical and reliable.
1996, 4(1): 60-64.
To search a simple low cost method of rock stresses measurement, a improved parallel boreholes method of rock stress determination with use of controlled fracturing technique is proposed. In this paper the feature of parallel boreholes method for observation of rock stresses and the principle of controlled fracturing technique are described.A foundamental theory of rock stress determination by boreholts stress change measurement using controlled tracturing technique is presented.
To search a simple low cost method of rock stresses measurement, a improved parallel boreholes method of rock stress determination with use of controlled fracturing technique is proposed. In this paper the feature of parallel boreholes method for observation of rock stresses and the principle of controlled fracturing technique are described.A foundamental theory of rock stress determination by boreholts stress change measurement using controlled tracturing technique is presented.
1996, 4(1): 65-69.
It is kowen in first regular examination of dam safity in China that there exists material separating from ground water to different extent in drainage holes and draingage galleries at dam foundations or foundation corridors of many constructed and operating dams. Large amount and yaring composition of the material found in some dams have attracted sttension from experts and the relevant persongs of electropower stations. This paper provides a result of study of mineralogical and chemical conposition, physico chemical properties, and granulometric composition of surrounding water, rockmass on dam foundation and the material operatingfrom ground water by measurement and determination methods from engineering geological and hydrogical aspects,revearls the formation mechanism of the material separating from the ground water,and evaluates the effect of the material on dam safity.
It is kowen in first regular examination of dam safity in China that there exists material separating from ground water to different extent in drainage holes and draingage galleries at dam foundations or foundation corridors of many constructed and operating dams. Large amount and yaring composition of the material found in some dams have attracted sttension from experts and the relevant persongs of electropower stations. This paper provides a result of study of mineralogical and chemical conposition, physico chemical properties, and granulometric composition of surrounding water, rockmass on dam foundation and the material operatingfrom ground water by measurement and determination methods from engineering geological and hydrogical aspects,revearls the formation mechanism of the material separating from the ground water,and evaluates the effect of the material on dam safity.
1996, 4(1): 70-74.
The strength deformation, failure characteristic of the fault gouge based on the conventional and creep test result are discussed in this paper, and the mechanical prepeties of the fault gouge are analysed under the interaction between water and rock.
The strength deformation, failure characteristic of the fault gouge based on the conventional and creep test result are discussed in this paper, and the mechanical prepeties of the fault gouge are analysed under the interaction between water and rock.
1996, 4(1): 75-79.
The rheological characteristics of incompetent rock are analysed by using U-t curves for the whole process of rheological deformation. The relationship between the rheological deformation rate p and stress a is given. The characteristic stress point of their rheological process is found on -d chart. The author proposes an approach to determine rheological stress of the crtical uniform rate rheololgical stress with ji-ij the inflection point of a curve and the principle of determining rheological strength is decribed.
The rheological characteristics of incompetent rock are analysed by using U-t curves for the whole process of rheological deformation. The relationship between the rheological deformation rate p and stress a is given. The characteristic stress point of their rheological process is found on -d chart. The author proposes an approach to determine rheological stress of the crtical uniform rate rheololgical stress with ji-ij the inflection point of a curve and the principle of determining rheological strength is decribed.
1996, 4(1): 80-85.
In this paper, the oharacterstics of environmental impact resulted from implementation of a water conservancy project is discussed, and the gradation structural system of regional environment impact factors is analysed by using the AHP method. For the complex conditions a method of quantitative avaluation of environmental impact is suggsted.As an example, the Nanyangqu water conservancy project in Gansu province is analyzed by this method, indicating the applicablity and effectiveness of the method.
In this paper, the oharacterstics of environmental impact resulted from implementation of a water conservancy project is discussed, and the gradation structural system of regional environment impact factors is analysed by using the AHP method. For the complex conditions a method of quantitative avaluation of environmental impact is suggsted.As an example, the Nanyangqu water conservancy project in Gansu province is analyzed by this method, indicating the applicablity and effectiveness of the method.
1996, 4(1): 86-90.
Coral reef is a special type of rock and soil. Coral reef engineering geology is a new sesearch field of engineering geology. It studies the phisical and mechanical characteristics of reef limestone and reef sand soil, avaluates the engineering geological conditions of caral reef and the influence of engineering projects on the environment of coral reef,and also provides scientific base for correct planing and rational design of engineering projects in coral reef zone. This paper presents a brief history of the coral reef engineering construction and the development engineering geology research in coral reef area since the late stage of the Second World War, and proposes the needs to strengthen the study of research field in our country.
Coral reef is a special type of rock and soil. Coral reef engineering geology is a new sesearch field of engineering geology. It studies the phisical and mechanical characteristics of reef limestone and reef sand soil, avaluates the engineering geological conditions of caral reef and the influence of engineering projects on the environment of coral reef,and also provides scientific base for correct planing and rational design of engineering projects in coral reef zone. This paper presents a brief history of the coral reef engineering construction and the development engineering geology research in coral reef area since the late stage of the Second World War, and proposes the needs to strengthen the study of research field in our country.
1996, 4(1): 91-96.
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