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Editor Work2002 Vol. 10, No. 2
Previous Issue
2002, 10(2): 115-117.
Abstract
A theory on coupling of earth's endogenic and exogenic geological processes is proporced to interpret origins serious geological dissters. In previous classifications and studies of natural disasters the endogenic geological disaster area and exogenic geological disaster area were distinguished, but no enough attention was paid to their counnections. In this paper it is argued that coupling of endogenic and exogenic geological processes is offen the overall origin of serious geological disasters in most of the active crustal movement area of China. It is also pointed out that study of the coupling of endogenic and exogenic geological processes related to serious geological disasters is important for their evaluation and prediction.
A theory on coupling of earth's endogenic and exogenic geological processes is proporced to interpret origins serious geological dissters. In previous classifications and studies of natural disasters the endogenic geological disaster area and exogenic geological disaster area were distinguished, but no enough attention was paid to their counnections. In this paper it is argued that coupling of endogenic and exogenic geological processes is offen the overall origin of serious geological disasters in most of the active crustal movement area of China. It is also pointed out that study of the coupling of endogenic and exogenic geological processes related to serious geological disasters is important for their evaluation and prediction.
2002, 10(2): 118-123.
In contrast to general statistics method, theory of nervous network has its remarkable characteristic, that is with study on previous sample book to grasp sophisticated nonlinear relation between input and output, to go on memory storage for this relation and to forecast uncertain sample book with association. The Author applied this theory to zoning evaluating the regional stability of the Heishan gorge of Huanghe River, and systematically proposed a program and a method for zoning evaluation of nervous network of region stability. The result indicates that this evaluation method is more concise and accurate than other methods.
In contrast to general statistics method, theory of nervous network has its remarkable characteristic, that is with study on previous sample book to grasp sophisticated nonlinear relation between input and output, to go on memory storage for this relation and to forecast uncertain sample book with association. The Author applied this theory to zoning evaluating the regional stability of the Heishan gorge of Huanghe River, and systematically proposed a program and a method for zoning evaluation of nervous network of region stability. The result indicates that this evaluation method is more concise and accurate than other methods.
2002, 10(2): 124-128.
The granitic rock mass existing in shiplock zone of the Three Gorges dam contains a number of major discontinuities,of them one hundred and thirty three major discontinuities have been mapped around the shiplock covering an area of 1740600m.These major discontinuities were analyzed by using block theory.However,it is important to keep in mind that discontinuities are finite and some key blocks are actually infinite blocks.In this paper,a stochastic model is incorporated into the key block theory to study the slide probability of key blocks on the high slope of the Three-Gorges of the Yangtze River,and the size and density distribution of blocks are also analyzed.The results provide a theoretical basis for the reinforcement of the high slope on the Three-Gorges of the Yangtze River and are of great significance in engineering practice.
The granitic rock mass existing in shiplock zone of the Three Gorges dam contains a number of major discontinuities,of them one hundred and thirty three major discontinuities have been mapped around the shiplock covering an area of 1740600m.These major discontinuities were analyzed by using block theory.However,it is important to keep in mind that discontinuities are finite and some key blocks are actually infinite blocks.In this paper,a stochastic model is incorporated into the key block theory to study the slide probability of key blocks on the high slope of the Three-Gorges of the Yangtze River,and the size and density distribution of blocks are also analyzed.The results provide a theoretical basis for the reinforcement of the high slope on the Three-Gorges of the Yangtze River and are of great significance in engineering practice.
2002, 10(2): 129-133.
In arid and semi-arid region, some engineering problems emerged due to the change of water content in soils. It is known that the behavior of unsaturated soil depends not only on the mineralogical composition, soil structure, and stress state, but also on soil suction. The relationships between water content and suction in the soil can be expressed as soil-water characteristic curves (SWCC). Based on the test on SWCC of an expansive soil, the result obtained by using osmotic techniques is compared with that by convenient method. The influence of the stress and suction histories on the SWCC is studied.
In arid and semi-arid region, some engineering problems emerged due to the change of water content in soils. It is known that the behavior of unsaturated soil depends not only on the mineralogical composition, soil structure, and stress state, but also on soil suction. The relationships between water content and suction in the soil can be expressed as soil-water characteristic curves (SWCC). Based on the test on SWCC of an expansive soil, the result obtained by using osmotic techniques is compared with that by convenient method. The influence of the stress and suction histories on the SWCC is studied.
2002, 10(2): 134-140.
Development and utilization of water resources must be closely combined with the preservation of cultural relics. That' s the case found in the plan and design of Middle Route Project of Water Transferring from South to North China. In this work, we investigate the river system, lithologic characteristics of geomorphic , grades of cultural relics their preservation situation and the spatial relation to the delivering canal. On the basis of these investigations, a statistics of the distribution characteristics of different-time cultural relics within 3km wide zones on both sides of delivering canal with respect to landforms was carried out. On the other hand, by using influence index E, a fuzzy quantitative appraisal of the influence degree on the cultural relics and their preservation graded was completed. Thr result enabled us to have a systematical recognition of the statistical characteristics of the cultural relics distributed within the 6 km wide zone. Meanwhile, it has also important referential and instructive meaning in planning of concrete sections of the project, adjustment of canal line, as well as design of impevious works.
Development and utilization of water resources must be closely combined with the preservation of cultural relics. That' s the case found in the plan and design of Middle Route Project of Water Transferring from South to North China. In this work, we investigate the river system, lithologic characteristics of geomorphic , grades of cultural relics their preservation situation and the spatial relation to the delivering canal. On the basis of these investigations, a statistics of the distribution characteristics of different-time cultural relics within 3km wide zones on both sides of delivering canal with respect to landforms was carried out. On the other hand, by using influence index E, a fuzzy quantitative appraisal of the influence degree on the cultural relics and their preservation graded was completed. Thr result enabled us to have a systematical recognition of the statistical characteristics of the cultural relics distributed within the 6 km wide zone. Meanwhile, it has also important referential and instructive meaning in planning of concrete sections of the project, adjustment of canal line, as well as design of impevious works.
2002, 10(2): 141-145.
The strength characteristics of the unsaturated soil in Beijing area were determined by using unsaturated triaxial apparatus at different matric suctions and a quantitatire relation between strength and matric suction was established. At the same time, we carried out a test of influence water content on the strength of the unsaturated soil. The result shows that the strength is raised at the different matric suctions and the change of water content obviously influences the cohesive force, but not remarkably influences the internal friction angle. We measured the turning point of water content to the strength changes of these specimens too.
The strength characteristics of the unsaturated soil in Beijing area were determined by using unsaturated triaxial apparatus at different matric suctions and a quantitatire relation between strength and matric suction was established. At the same time, we carried out a test of influence water content on the strength of the unsaturated soil. The result shows that the strength is raised at the different matric suctions and the change of water content obviously influences the cohesive force, but not remarkably influences the internal friction angle. We measured the turning point of water content to the strength changes of these specimens too.
2002, 10(2): 146-151.
By using e of the theory of elasticity and variation method, the problem of ground stress field in V-shaped river valleys is studied. The stress formulae can be used to draw various stress curves, but also to calculate the stress values at stability, rock mass staiblity around the underground excavations and to design hydropower dams and slope engineering project.
By using e of the theory of elasticity and variation method, the problem of ground stress field in V-shaped river valleys is studied. The stress formulae can be used to draw various stress curves, but also to calculate the stress values at stability, rock mass staiblity around the underground excavations and to design hydropower dams and slope engineering project.
2002, 10(2): 152-155.
The opening is a basis for development and evolution of a slope system which is composed of a lot of small systems. In order to study the opening of slope evolution, a concept of opening is put forward and its theoretical formula is presented. The relationship between the opening degree (P) and the entropy is discussed theoretically.
The opening is a basis for development and evolution of a slope system which is composed of a lot of small systems. In order to study the opening of slope evolution, a concept of opening is put forward and its theoretical formula is presented. The relationship between the opening degree (P) and the entropy is discussed theoretically.
2002, 10(2): 156-159.
There is some ambiguity about the soil-nail interaction mechanism in the design of soil nailing reinforcement. The paper presents a shear model for explaining the soil-nail interaction. The model is proved to be vailed through a case study. Also, the soil-nail interaction mechanism is studied by using the model.
There is some ambiguity about the soil-nail interaction mechanism in the design of soil nailing reinforcement. The paper presents a shear model for explaining the soil-nail interaction. The model is proved to be vailed through a case study. Also, the soil-nail interaction mechanism is studied by using the model.
2002, 10(2): 160-165.
The structural plane exists also in soil mass and is concerned with geotechnical engineering problems. This paper studies geotechnical engineering problem's in consideration of structural plane of soil mass, in order to attract attention to the structural plane of soil mass. These problems are that , the structural plane has control over the failure of soil mass and affects the mechanical properties of soil mass,soil slope stability and mechanical parameter ets, etc., as along the structural plane the water and pollutants can transport and percolate in the soil mass. It can be analysed by using DEM model for soil mass.
The structural plane exists also in soil mass and is concerned with geotechnical engineering problems. This paper studies geotechnical engineering problem's in consideration of structural plane of soil mass, in order to attract attention to the structural plane of soil mass. These problems are that , the structural plane has control over the failure of soil mass and affects the mechanical properties of soil mass,soil slope stability and mechanical parameter ets, etc., as along the structural plane the water and pollutants can transport and percolate in the soil mass. It can be analysed by using DEM model for soil mass.
2002, 10(2): 166-171.
Environmental geological and geomorphological conditions along a river are the important factors affecting the construction and development of an alongshore city and its environmental features and are also the backgrounds determining the environmental quality and functions of the cities along the river and the whole natural environment.Therefore,investigation of environmental geology and geomorphology along the river is of important theoretical and practical significance not only in improving the environmental quality and capacity of the city on the river.Take the Fuzhou section of Minjiang River as an example,in this paper a brief account and analysis of hydrodynamic conditions and change of hydrodynamic factors in time and space are taken.We have analyzed and studied the geomorphologic and geological characteristics of the southern and northern ports of Fuzhou section of Minjiang River and their evolutional tendency;the interaction of all kinds of human engineering constructions along river and the patterns and strength of geological effect and geomorphologic environment of the southern and northern ports. The results show that amount of water flow in northern port of Mingjiang River riverbed increases year after year,water level drops and sand content decreases every year;amount of water flow in southern post of Minjiang River decreases year after year,but water level rises.All kinds of human activities such as engineering construction,intensify the difference in amount of runoff and water level in the southern and northern ports of Minjiang River,promote and strengthen the erosive effect on northern port and siltation effect on southern port.and make the geological and geomorphologic environments for southern and northern ports of Minjiang River develop in an unstable direction.The deterioration of geological and geomorphologic environments for the southern and northern ports of Minjiang river reflects the result of all kinds of unregular human activities,such as engineering construction,and hence the stability and security of the engineering projects which have been built or in building or in planning to build are and will be lost damaged greatly.
Environmental geological and geomorphological conditions along a river are the important factors affecting the construction and development of an alongshore city and its environmental features and are also the backgrounds determining the environmental quality and functions of the cities along the river and the whole natural environment.Therefore,investigation of environmental geology and geomorphology along the river is of important theoretical and practical significance not only in improving the environmental quality and capacity of the city on the river.Take the Fuzhou section of Minjiang River as an example,in this paper a brief account and analysis of hydrodynamic conditions and change of hydrodynamic factors in time and space are taken.We have analyzed and studied the geomorphologic and geological characteristics of the southern and northern ports of Fuzhou section of Minjiang River and their evolutional tendency;the interaction of all kinds of human engineering constructions along river and the patterns and strength of geological effect and geomorphologic environment of the southern and northern ports. The results show that amount of water flow in northern port of Mingjiang River riverbed increases year after year,water level drops and sand content decreases every year;amount of water flow in southern post of Minjiang River decreases year after year,but water level rises.All kinds of human activities such as engineering construction,intensify the difference in amount of runoff and water level in the southern and northern ports of Minjiang River,promote and strengthen the erosive effect on northern port and siltation effect on southern port.and make the geological and geomorphologic environments for southern and northern ports of Minjiang River develop in an unstable direction.The deterioration of geological and geomorphologic environments for the southern and northern ports of Minjiang river reflects the result of all kinds of unregular human activities,such as engineering construction,and hence the stability and security of the engineering projects which have been built or in building or in planning to build are and will be lost damaged greatly.
2002, 10(2): 172-176.
An advance in highway tunnel waterproofing and drainage techniques in last decades is summarized in the paper, including technical standards the highway tunnel waterproofing technical standards, the composite lining waterproofing techniques, the waterproofing technologies in fault and rupture zones, the tunnel drainage system. The usages of the waterproofing techniques mentioned are discussed in connection with engineering practice.
An advance in highway tunnel waterproofing and drainage techniques in last decades is summarized in the paper, including technical standards the highway tunnel waterproofing technical standards, the composite lining waterproofing techniques, the waterproofing technologies in fault and rupture zones, the tunnel drainage system. The usages of the waterproofing techniques mentioned are discussed in connection with engineering practice.
2002, 10(2): 177-183.
With development of the existing buildings reconstruction, the foundation reinforcement treatment for improving soil properties of the existing building foundation is frequently conducted. Therefore, how to test the rational quality of foundation reinforcement is very important to ensure safety of this type of reconstructed buildings. In this paper, taking a reconstructed existing building reinforced by high-pressure grouting, as an example, we discussed in details how to test and evaluate the foundation reinforcement of the existing building.
With development of the existing buildings reconstruction, the foundation reinforcement treatment for improving soil properties of the existing building foundation is frequently conducted. Therefore, how to test the rational quality of foundation reinforcement is very important to ensure safety of this type of reconstructed buildings. In this paper, taking a reconstructed existing building reinforced by high-pressure grouting, as an example, we discussed in details how to test and evaluate the foundation reinforcement of the existing building.
2002, 10(2): 184-188.
A CFG composite foundation was planed, but it is very difficult to be treated in construction due to complicated geologic stratum. Thus, two pile diameters(400 and 800) are adopted to improve the foundation. But theplaned foundation could undergo different settlement of foundation and brings bad influence on building because of different pile diameter. So it is very important to select the appropriate pile spacing. To solve this problem, this paper compares four different pile spacings by 3D settlement analysis of composite foundation, then an optimum plan is put forward.
A CFG composite foundation was planed, but it is very difficult to be treated in construction due to complicated geologic stratum. Thus, two pile diameters(400 and 800) are adopted to improve the foundation. But theplaned foundation could undergo different settlement of foundation and brings bad influence on building because of different pile diameter. So it is very important to select the appropriate pile spacing. To solve this problem, this paper compares four different pile spacings by 3D settlement analysis of composite foundation, then an optimum plan is put forward.
2002, 10(2): 189-192.
The paper describes the construction and operation of groundwater monitoring network on the Changjiang Three-Gorges Reservoir induced earthquakes and the result of tentative operation and examination. Moreover, the inner quality of monitoring data are analyzed and evaluated. The results show that the data from the network are of relatively high inner quality. They can be used to provide not only groundwater precursor for predication of the trend of reservoir-induced seismicity above a certain magnitude, but also the valuable data and reference for further study of reservoir-induced earthquakes.
The paper describes the construction and operation of groundwater monitoring network on the Changjiang Three-Gorges Reservoir induced earthquakes and the result of tentative operation and examination. Moreover, the inner quality of monitoring data are analyzed and evaluated. The results show that the data from the network are of relatively high inner quality. They can be used to provide not only groundwater precursor for predication of the trend of reservoir-induced seismicity above a certain magnitude, but also the valuable data and reference for further study of reservoir-induced earthquakes.
2002, 10(2): 193-197.
The definition of overbreak and Relation between unstable block's volume and overbroken volume are discussed, and the methods to calculate block's position and volume are summed up to 3 kind: stochastic, determinate and half-stochastic, and instruction is put forward for further study on overbreak. The determinate calculation about position of the block incised by 3 joints, especially the hidden dangerous block are discussed and settled, and a simple method to calculate the block's volume approximatively is advanced. The overbreak calculation is instructionally significative in safe and efficient underground opening construction.
The definition of overbreak and Relation between unstable block's volume and overbroken volume are discussed, and the methods to calculate block's position and volume are summed up to 3 kind: stochastic, determinate and half-stochastic, and instruction is put forward for further study on overbreak. The determinate calculation about position of the block incised by 3 joints, especially the hidden dangerous block are discussed and settled, and a simple method to calculate the block's volume approximatively is advanced. The overbreak calculation is instructionally significative in safe and efficient underground opening construction.
2002, 10(2): 198-203.
The problems existing in rock mass in-situ test, in present selection of deformation parameter, and in conventional compution model are analyzed. Based on the weathering, wave velocity and ground stress of rock masses having their progressive changes from superficial to deep part, a selection of the proggressively changing rock mass deformation parameter is presented. The displacement values monitored during the time of initial impoundment of the reservoir of Lijiaxia Hydropower Station in the upstream of Yellow River prove the reasonableness of the selection of progressively changing rock mass deformation parameters in space. The result is of realistic guiding significance for selection of mechanical parameters and the generalization of compution model in other rock mass engineering projects in the future.
The problems existing in rock mass in-situ test, in present selection of deformation parameter, and in conventional compution model are analyzed. Based on the weathering, wave velocity and ground stress of rock masses having their progressive changes from superficial to deep part, a selection of the proggressively changing rock mass deformation parameter is presented. The displacement values monitored during the time of initial impoundment of the reservoir of Lijiaxia Hydropower Station in the upstream of Yellow River prove the reasonableness of the selection of progressively changing rock mass deformation parameters in space. The result is of realistic guiding significance for selection of mechanical parameters and the generalization of compution model in other rock mass engineering projects in the future.
2002, 10(2): 204-209.
The formulations and numerical modeling of several conceptual models for unsaturated groundwater flow and solute transport in fractured rocks,such as fracture-network models,continuum models,effective continuum models,dual-porosity(single-permeability)models,dual-permeability models,and multiple interacting continua models are discussed in this paper.In a fractured rock-mass,unsaturated groundwater flow could occur either in the rock matrix only or in the fracture network only,or in both the rock matrix and the fractures.For the former situation,only a single continuum needs to be considered,whereas for the latter,interchange flow at matrixfracture interface has to be taken into account.Generally,fracture network constitutes the main channel of solute migration;however,if the seepage and diffusion of solute between the fractures and the rock matrix become an important transport mechanism,solute interchange at matrix-fracture interface needs to be considered.In order to model such groundwater and solute interchanges,one must decide the form and extent of matrix-fracture interac tions,which result in extra uncertainties in the conceptual models as opposed to single-continuum models.and make the numerical modeling more difficult.In practice,it is not easy,or even not possible at all,to discern the exact form of unsaturated seepage,selection of the conceptual models largely depends upon the modeling objective and the extent of data acquisition and understanding about the site.Any model will be affected by the uncertainties involved in the model and model parameters.Therefore,it is necessary to consider comparisons with other complementary models.
The formulations and numerical modeling of several conceptual models for unsaturated groundwater flow and solute transport in fractured rocks,such as fracture-network models,continuum models,effective continuum models,dual-porosity(single-permeability)models,dual-permeability models,and multiple interacting continua models are discussed in this paper.In a fractured rock-mass,unsaturated groundwater flow could occur either in the rock matrix only or in the fracture network only,or in both the rock matrix and the fractures.For the former situation,only a single continuum needs to be considered,whereas for the latter,interchange flow at matrixfracture interface has to be taken into account.Generally,fracture network constitutes the main channel of solute migration;however,if the seepage and diffusion of solute between the fractures and the rock matrix become an important transport mechanism,solute interchange at matrix-fracture interface needs to be considered.In order to model such groundwater and solute interchanges,one must decide the form and extent of matrix-fracture interac tions,which result in extra uncertainties in the conceptual models as opposed to single-continuum models.and make the numerical modeling more difficult.In practice,it is not easy,or even not possible at all,to discern the exact form of unsaturated seepage,selection of the conceptual models largely depends upon the modeling objective and the extent of data acquisition and understanding about the site.Any model will be affected by the uncertainties involved in the model and model parameters.Therefore,it is necessary to consider comparisons with other complementary models.
2002, 10(2): 210-215.
Jiaoxin railway recently in construction is across the Yishu fault belt which belong to famous Tanlu tectonic belt, marked by intense neotectonism and frequent seismic activity. In this case, it seems necessary to conduct a quantitative assessment and zonation of the regional crustal stability for site selecting of the Jiaoxin railway. Based on the quantitative system of classifying earth crust stability, a number of elemental parameters, including tectonic background of the region of south Shandong province, character of active faults, as well as seismological parameters, are studied considering the demand of the site selecting of Jiaoxin railway. The crustal stability is classified as stable, basically stable, comparatively stable, lack stable, and unstable. A fuzzy comprehensive analysis method is used to determine the grade of the stability. The evaluation factors and weights are taken from the results of the hierarchical analysis. By this system, the charts of the tectonic stability and crust stability partition are made. Finally, the site selecting between Zhucheng city to Xinyi city is made for Jiaoxin railway.
Jiaoxin railway recently in construction is across the Yishu fault belt which belong to famous Tanlu tectonic belt, marked by intense neotectonism and frequent seismic activity. In this case, it seems necessary to conduct a quantitative assessment and zonation of the regional crustal stability for site selecting of the Jiaoxin railway. Based on the quantitative system of classifying earth crust stability, a number of elemental parameters, including tectonic background of the region of south Shandong province, character of active faults, as well as seismological parameters, are studied considering the demand of the site selecting of Jiaoxin railway. The crustal stability is classified as stable, basically stable, comparatively stable, lack stable, and unstable. A fuzzy comprehensive analysis method is used to determine the grade of the stability. The evaluation factors and weights are taken from the results of the hierarchical analysis. By this system, the charts of the tectonic stability and crust stability partition are made. Finally, the site selecting between Zhucheng city to Xinyi city is made for Jiaoxin railway.
2002, 10(2): 216-219.
The ground micro-tremor signals were observed in Fuzhou, Quanzhou and Putian of Fujian Province, and the signals are analyzed by fast Fourier transform method. The result shows that at the sites with greater thickness of overburden layers intercalating a thick weak layer, the rigidity of the ground is low, the frequency band is wider, the frequency energy is rather disperse, the peak frequency is lower with predominate frequency of 1～5Hz commonly; However, the sites with thinner of overburden layers, and greater rigidity of the ground, the frequency band is narrower, and the peak frequency is higher with predominate frequency of 8～11Hz. Soft soil can filter high frequency signals, but can amplify low frequency signals.
The ground micro-tremor signals were observed in Fuzhou, Quanzhou and Putian of Fujian Province, and the signals are analyzed by fast Fourier transform method. The result shows that at the sites with greater thickness of overburden layers intercalating a thick weak layer, the rigidity of the ground is low, the frequency band is wider, the frequency energy is rather disperse, the peak frequency is lower with predominate frequency of 1～5Hz commonly; However, the sites with thinner of overburden layers, and greater rigidity of the ground, the frequency band is narrower, and the peak frequency is higher with predominate frequency of 8～11Hz. Soft soil can filter high frequency signals, but can amplify low frequency signals.
2002, 10(2): 220-224.
An integrated geological and geophysical investigation suggests that the landslide at Badu K343 occurred because the top of strong weathering zone on sandstone is rich in kaolin and other minerals which became liguid layer by water saturation after torrential rain and caused the weathering zone and loose sediments to undergo gravity instability. The landslide body is about 20 m in thickness, 30 thousand m 2 in cover area, and 600 thousand m 3 in the slip volume. Based on the investigation of geological conditions, a proposal on building of piles and ditches for control on the landslide is suggested.
An integrated geological and geophysical investigation suggests that the landslide at Badu K343 occurred because the top of strong weathering zone on sandstone is rich in kaolin and other minerals which became liguid layer by water saturation after torrential rain and caused the weathering zone and loose sediments to undergo gravity instability. The landslide body is about 20 m in thickness, 30 thousand m 2 in cover area, and 600 thousand m 3 in the slip volume. Based on the investigation of geological conditions, a proposal on building of piles and ditches for control on the landslide is suggested.
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