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Editor Work2002 Vol. 10, No. 3
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2002, 10(3): 227-232.
Abstract
The geologically dangerous sections formed by geologic agent can be distinguished into three kinds, such as neotectonically dangerous section, subsidence - dangerous section, and reactivation-dangerous section. Percolation sections of embankment foundation, earthquake damage sections, and weak stability sections of embankment foundation are of a part of geologically dangerous sections. According to the geological features of the lower Yellow River, three Geologically dangerous sections can be identified, such as Dongbatou, Daliutun-Dongkou, and Lunali-Shilipu sections. Some countermeasures are suggested in this paper.
The geologically dangerous sections formed by geologic agent can be distinguished into three kinds, such as neotectonically dangerous section, subsidence - dangerous section, and reactivation-dangerous section. Percolation sections of embankment foundation, earthquake damage sections, and weak stability sections of embankment foundation are of a part of geologically dangerous sections. According to the geological features of the lower Yellow River, three Geologically dangerous sections can be identified, such as Dongbatou, Daliutun-Dongkou, and Lunali-Shilipu sections. Some countermeasures are suggested in this paper.
2002, 10(3): 233-236.
End constraint has an influence on distribution of stress in rock specimen, failure pattern and pattern of shear zone. FLAC-3D is adopted to simulate the influence of end constraint on patterns of shear bands, velocity and displacement fields. For a stiffer constraint, a conjugate shear zone occured in central part of the specimen; Otherwise, an inclined shear zone initiated on the end of the specimen. The inclination angle of shear zone becomes steeper with increasing rigidity of platen. Four small blocks have properties of integral movement. The displacement gradient along the margin shear zone is larger. It shows that the blocks slide alone shear zone is of shear failure nature. The result of numerical simulation is consistent with some experimental results.
End constraint has an influence on distribution of stress in rock specimen, failure pattern and pattern of shear zone. FLAC-3D is adopted to simulate the influence of end constraint on patterns of shear bands, velocity and displacement fields. For a stiffer constraint, a conjugate shear zone occured in central part of the specimen; Otherwise, an inclined shear zone initiated on the end of the specimen. The inclination angle of shear zone becomes steeper with increasing rigidity of platen. Four small blocks have properties of integral movement. The displacement gradient along the margin shear zone is larger. It shows that the blocks slide alone shear zone is of shear failure nature. The result of numerical simulation is consistent with some experimental results.
2002, 10(3): 237-243.
The paper focuses on the apparent cohesion of the unsaturated sand. The efforts have been done in the laboratory to use organic materials, clay, and Dutch black peat to improve the apparent cohesion of the unsaturated sands. Five types of sand, organic material, black peat, bentonite and kaolinite have been chosen to probe the cohesive characteristics of sand under unsaturation state. The test results shown that the sand shows some cohesion under unsaturation state and some material shows a significant increase in apparent cohesion of unsaturated sand.
The paper focuses on the apparent cohesion of the unsaturated sand. The efforts have been done in the laboratory to use organic materials, clay, and Dutch black peat to improve the apparent cohesion of the unsaturated sands. Five types of sand, organic material, black peat, bentonite and kaolinite have been chosen to probe the cohesive characteristics of sand under unsaturation state. The test results shown that the sand shows some cohesion under unsaturation state and some material shows a significant increase in apparent cohesion of unsaturated sand.
2002, 10(3): 244-247.
The engineering site is far apart from city by spatial scale but the engineering site provides environmental behaviors of approximate common character. Its attributive analysis may be applied to the entire engineering geologic environment faced by urban construction. In this sense, engineering site is a microunit of the entire urban macro engineering geologic environment. The combination of many microunits constitutes the macro overall of environment. Hence, the three attributes of engineering site - property, suitability, stability, may be used as bases of analytic methods in the analyses of urban engineering geologic environment. Spreading engineering site analysis to urban engineering geologic environment analysis will be helpful to guarantee to quantitative level of urban engineering geologic environment analysis.
The engineering site is far apart from city by spatial scale but the engineering site provides environmental behaviors of approximate common character. Its attributive analysis may be applied to the entire engineering geologic environment faced by urban construction. In this sense, engineering site is a microunit of the entire urban macro engineering geologic environment. The combination of many microunits constitutes the macro overall of environment. Hence, the three attributes of engineering site - property, suitability, stability, may be used as bases of analytic methods in the analyses of urban engineering geologic environment. Spreading engineering site analysis to urban engineering geologic environment analysis will be helpful to guarantee to quantitative level of urban engineering geologic environment analysis.
2002, 10(3): 248-253.
In the article ,the authors mainly study and calculate a significant engineering problem about water leakage in left dam abutment of Heihe Reservoir. A three-dimensional finite difference method is used to simulate seepage flow under natural conditions and high hydraulic head was simulated, the way of percolation was analyze and the quantity of leakage at left dam abutment of Heihe Reservoir was calculated. A fact that the fault became a conduit for intensive percolation is verified by the calculation. Then according to hydraulic head, using three-dimension finite-difference method, we calculate water table and the stability of slope at left dam abutment is studied and analyzed by using limit equilibrium analysis method. All the results are of important referential value for the decision -making and design of practical engineering project.
In the article ,the authors mainly study and calculate a significant engineering problem about water leakage in left dam abutment of Heihe Reservoir. A three-dimensional finite difference method is used to simulate seepage flow under natural conditions and high hydraulic head was simulated, the way of percolation was analyze and the quantity of leakage at left dam abutment of Heihe Reservoir was calculated. A fact that the fault became a conduit for intensive percolation is verified by the calculation. Then according to hydraulic head, using three-dimension finite-difference method, we calculate water table and the stability of slope at left dam abutment is studied and analyzed by using limit equilibrium analysis method. All the results are of important referential value for the decision -making and design of practical engineering project.
2002, 10(3): 254-259.
The distribution and exploitation of mineral resources in Heilongjiang Province are of importance in development of economy in Heilongjiang Province. The ecological destruction and geological hazards caused by exploitation of minerals had attracted great attentions. Some concrete measures to prevent and control on them after discussion upon advantages and disadvantages emerging in development of mining in Heilongjiang Province are suggested in the paper.
The distribution and exploitation of mineral resources in Heilongjiang Province are of importance in development of economy in Heilongjiang Province. The ecological destruction and geological hazards caused by exploitation of minerals had attracted great attentions. Some concrete measures to prevent and control on them after discussion upon advantages and disadvantages emerging in development of mining in Heilongjiang Province are suggested in the paper.
2002, 10(3): 260-265.
Based on the field engineering-geological explortation and rock mechanics test, a study of geological model for dam foundation of Shuibuya Hydropower Station is carried out. The engineering-geological rock group and rockmass structure for Shuibuya dam foundation are studied. The conceptual geological model for the Shuibuya dam foundation is developed. The results of rockmass quality assessment and rockmass mechanical parameter are presented in the paper.
Based on the field engineering-geological explortation and rock mechanics test, a study of geological model for dam foundation of Shuibuya Hydropower Station is carried out. The engineering-geological rock group and rockmass structure for Shuibuya dam foundation are studied. The conceptual geological model for the Shuibuya dam foundation is developed. The results of rockmass quality assessment and rockmass mechanical parameter are presented in the paper.
2002, 10(3): 266-273.
Adopting the definition suggested by the United Nations, debris flow risk is used to measure the expected losses (losses of lives, person injured, property damage, and economic activity disrupted) due debris flows for a specified area and during a reference period. Under the mathematical proposition of Risk is the product of hazard and vulnerability given by the United Nations, the present paper has obtained an approximate quantitative solution for empirically assessing debris flow risk. Site-specific debris flow risk assessment model is a multiple factor composite assessment model including seven factors, and site-specific debris flow vulnerability assessment model is a nonlinear complex function model including seven indexes, so site-specific debris flow risk assessment model is practically a synthetic model comprising of 14 variables. This paper has also discussed the classes of debris flow risk and their probability distribution. Among the five classes, from the statistical viewpoint, the very low risk class occurs with a probability of 16.88%; the low risk class occurs with a probability of 28.44%; the moderate risk class occurs with a probability of 27.46%; the high risk class occurs with a probability of 19.78%; the very high risk class occurs with a probability of 7.44%. A case study in Heishan gully of Yinmin copper mine of Dongchuan in Yunnan province has been used to demonstrate the procedures of the method for site-specific debris flow risk assessment.
Adopting the definition suggested by the United Nations, debris flow risk is used to measure the expected losses (losses of lives, person injured, property damage, and economic activity disrupted) due debris flows for a specified area and during a reference period. Under the mathematical proposition of Risk is the product of hazard and vulnerability given by the United Nations, the present paper has obtained an approximate quantitative solution for empirically assessing debris flow risk. Site-specific debris flow risk assessment model is a multiple factor composite assessment model including seven factors, and site-specific debris flow vulnerability assessment model is a nonlinear complex function model including seven indexes, so site-specific debris flow risk assessment model is practically a synthetic model comprising of 14 variables. This paper has also discussed the classes of debris flow risk and their probability distribution. Among the five classes, from the statistical viewpoint, the very low risk class occurs with a probability of 16.88%; the low risk class occurs with a probability of 28.44%; the moderate risk class occurs with a probability of 27.46%; the high risk class occurs with a probability of 19.78%; the very high risk class occurs with a probability of 7.44%. A case study in Heishan gully of Yinmin copper mine of Dongchuan in Yunnan province has been used to demonstrate the procedures of the method for site-specific debris flow risk assessment.
2002, 10(3): 274-278.
In engineering geological practice, the evidence to identify a fault as an active one is the latest time at which the fault ruptured the surface or subsurface if no other data are available. So drafting of the time criterion in a region is a key work with had better be based on both scientific and engineering safety consideration. The time criterion depends on our understanding to some extent on the periodical and repeatable features of tectonic movements. There occurred a widespread tectonic movement in late Pleistocene (about 30 thousand years B.P.) in China. The tectonic deformation have entered a new stage since then. This fact is the scientific basis for determining the time criterion. Therefore, the time criterion determined on the basis of it means that fautl activated or reactivated in the past 30 thousand years could be identified as engineering active ones in continent of China.
In engineering geological practice, the evidence to identify a fault as an active one is the latest time at which the fault ruptured the surface or subsurface if no other data are available. So drafting of the time criterion in a region is a key work with had better be based on both scientific and engineering safety consideration. The time criterion depends on our understanding to some extent on the periodical and repeatable features of tectonic movements. There occurred a widespread tectonic movement in late Pleistocene (about 30 thousand years B.P.) in China. The tectonic deformation have entered a new stage since then. This fact is the scientific basis for determining the time criterion. Therefore, the time criterion determined on the basis of it means that fautl activated or reactivated in the past 30 thousand years could be identified as engineering active ones in continent of China.
2002, 10(3): 279-283.
Debris flow is a suddenly occurring natural hazard in mountain areas over the world. The debris formation and movement are complex. There are several methods for predicting the debris flow, but it is still an important problem considered by geo-scientists. The purpose of debris flow predicting,forecasting and warning is to protect the properties and lives. The prediction of debris flow is on the basis of analysis of debris conditions and understanding of the possibility of its occurrence. The purpose of debris flow prediction and warning is to protect peopless life and proprty. Prediction and waring of debris flow are made at several stages before its occurrence.
Debris flow is a suddenly occurring natural hazard in mountain areas over the world. The debris formation and movement are complex. There are several methods for predicting the debris flow, but it is still an important problem considered by geo-scientists. The purpose of debris flow predicting,forecasting and warning is to protect the properties and lives. The prediction of debris flow is on the basis of analysis of debris conditions and understanding of the possibility of its occurrence. The purpose of debris flow prediction and warning is to protect peopless life and proprty. Prediction and waring of debris flow are made at several stages before its occurrence.
2002, 10(3): 284-287.
Pile - foundation is one of the safe and reliable measures for main buildings and constructions of large - scale engineering project in the area , where the upper part consists of failling granite fragments, the lower part consist of soft clay, and groundwater and seawater are connected with each other. What type pile will be selected and how can penetrate through the filling granite fragements successfully? These questions are worthy to be studied. A process of preparing lead-holes in the granite fragements filling using dive-hole hammer, and back filling gravel into the lead-holes, then driving H-shaped, was perfermed. The obtained result of the foundation streatment for a power plant in Shenzhen city is better.
Pile - foundation is one of the safe and reliable measures for main buildings and constructions of large - scale engineering project in the area , where the upper part consists of failling granite fragments, the lower part consist of soft clay, and groundwater and seawater are connected with each other. What type pile will be selected and how can penetrate through the filling granite fragements successfully? These questions are worthy to be studied. A process of preparing lead-holes in the granite fragements filling using dive-hole hammer, and back filling gravel into the lead-holes, then driving H-shaped, was perfermed. The obtained result of the foundation streatment for a power plant in Shenzhen city is better.
2002, 10(3): 288-292.
The causes affecting on the installation depth of hydraulically preformed pile and the distribution regularities of bearing capacity, taking one power plant in Henan Province as a case, are studied from in-situ tests results in this paper. The study result indicates that the installation depth of the pile and its bearing capacity are affected by the property of foundation soil. In the case study, though the depth of pile is smaller than that designed, the bearing capacity is enough to meet the need of construction.
The causes affecting on the installation depth of hydraulically preformed pile and the distribution regularities of bearing capacity, taking one power plant in Henan Province as a case, are studied from in-situ tests results in this paper. The study result indicates that the installation depth of the pile and its bearing capacity are affected by the property of foundation soil. In the case study, though the depth of pile is smaller than that designed, the bearing capacity is enough to meet the need of construction.
A CASE STUDY ON TBM BLOCK IN MARLS AT CONNECTION WORKS NO.7 TUNNEL OF YELLOW RIVER DIVERSION PROJECT
2002, 10(3): 293-298.
This paper presents a case study on an exceptional event of TBM blocking in a section of the Connection Works No.7 tunnel of Yellow River Diversion Project in China. By analysis of lithology, fold, rock mass strength and geo-stress, it indicates that a high rate deformation with respect to inter-layer shear zone in the lower part of the anticlinal core is a dominant factor resulting in TBM blocking. Also the previously encountered unfavorable conditions in forms of wet clay, groundwater inflow, and cavities are coincident with tensile stress in lower part of the syncline. The syncline and anticline make the fold. Based on these diagnoses, economical and quick curing measurements such as enlargement excavation outside of the shield leaving free space to unlock the TBM were adopted. After 9 days blocking, the TBM was totally released and undertaken normal excavation again. Unlike those frequently encountered and discussed unfavorable geological conditions such as jointed, fractured rock mass and faulted zone, this instance mostly highlights a lesson learnt from folding and inter-layer shear zone in TBM tunneling.
This paper presents a case study on an exceptional event of TBM blocking in a section of the Connection Works No.7 tunnel of Yellow River Diversion Project in China. By analysis of lithology, fold, rock mass strength and geo-stress, it indicates that a high rate deformation with respect to inter-layer shear zone in the lower part of the anticlinal core is a dominant factor resulting in TBM blocking. Also the previously encountered unfavorable conditions in forms of wet clay, groundwater inflow, and cavities are coincident with tensile stress in lower part of the syncline. The syncline and anticline make the fold. Based on these diagnoses, economical and quick curing measurements such as enlargement excavation outside of the shield leaving free space to unlock the TBM were adopted. After 9 days blocking, the TBM was totally released and undertaken normal excavation again. Unlike those frequently encountered and discussed unfavorable geological conditions such as jointed, fractured rock mass and faulted zone, this instance mostly highlights a lesson learnt from folding and inter-layer shear zone in TBM tunneling.
2002, 10(3): 299-304.
Applied the principle of neural network theory, a model for prediction karstic ground collapse has been set up though learning some examples of karstic ground collapses. This model was used in prediction of the karstic ground collapses in one city is predicted. The result shows that neural network has high accuracy, fast convergence vate, and high allowable error ability, and it has wide application foreground in the research of karstic ground collapse.
Applied the principle of neural network theory, a model for prediction karstic ground collapse has been set up though learning some examples of karstic ground collapses. This model was used in prediction of the karstic ground collapses in one city is predicted. The result shows that neural network has high accuracy, fast convergence vate, and high allowable error ability, and it has wide application foreground in the research of karstic ground collapse.
2002, 10(3): 305-308.
A new hybrid-genetic algorithm is presented by introducing Powell method into genetic algorithm of numerical optimization, and a new method for calculation of failure probability of slope is developed for Yamansu iron mine in Xinjiang autonomous region. The analysis result shows that the proposed method, which can be easily used to find out the total optimum point, is practical and reliable.
A new hybrid-genetic algorithm is presented by introducing Powell method into genetic algorithm of numerical optimization, and a new method for calculation of failure probability of slope is developed for Yamansu iron mine in Xinjiang autonomous region. The analysis result shows that the proposed method, which can be easily used to find out the total optimum point, is practical and reliable.
2002, 10(3): 309-312.
The main engineering project of flood controlling in the middle and lower reaches of the Changjiang River implemented on the back levee of the Changjiang River.The Changjaing River embankment, a long course and a large project, has a mass of existing geological data.The hydrologic and geologic conditions for the embankment foundation are complex. Henceforth in the engineering-geological investigation work repairing and reinforcing the embankment, it is necessary to collect, store, index, analyse, count and maintain data as well as to transfer these data in order to synthesise and compile reports and maps at any moment.In flood season, the related data can be provided for inquiry and transfer of concerned files, or maps in decision making and used intaking measures dealing with an emergency. It increase the value in use and utilization of geological data, in the same way, it ensures the veracity, integrality and share of the imformation. Therefore, it is important to constitute reasonable Changjiang River embankment engineering geological information processing model and to get this technical method mature.
The main engineering project of flood controlling in the middle and lower reaches of the Changjiang River implemented on the back levee of the Changjiang River.The Changjaing River embankment, a long course and a large project, has a mass of existing geological data.The hydrologic and geologic conditions for the embankment foundation are complex. Henceforth in the engineering-geological investigation work repairing and reinforcing the embankment, it is necessary to collect, store, index, analyse, count and maintain data as well as to transfer these data in order to synthesise and compile reports and maps at any moment.In flood season, the related data can be provided for inquiry and transfer of concerned files, or maps in decision making and used intaking measures dealing with an emergency. It increase the value in use and utilization of geological data, in the same way, it ensures the veracity, integrality and share of the imformation. Therefore, it is important to constitute reasonable Changjiang River embankment engineering geological information processing model and to get this technical method mature.
2002, 10(3): 313-316.
Using R-wave dispersion phase velocity we can reverse S-wave velocity group of geologic strata. The R-wave method has effective applicability for engineering site because of its characteristics. In detection of the existing foundation Wangjing～Hepingli Railroad, combining the CDP method of multi-trace reflection technology and R-wave spectral analysis technique, we obtain 2-D S-wave velocity profile. According to the coherence between S-wave velocitiy and the value of light dynamic penetration test, we can evaluate the railroad foundation in vertical and horizontal direction.
Using R-wave dispersion phase velocity we can reverse S-wave velocity group of geologic strata. The R-wave method has effective applicability for engineering site because of its characteristics. In detection of the existing foundation Wangjing～Hepingli Railroad, combining the CDP method of multi-trace reflection technology and R-wave spectral analysis technique, we obtain 2-D S-wave velocity profile. According to the coherence between S-wave velocitiy and the value of light dynamic penetration test, we can evaluate the railroad foundation in vertical and horizontal direction.
2002, 10(3): 317-320.
On the base of existing methods for computing the cable s prestressing force in design of anti-slide pile with prestressed cable, we consider the change of horizontal sliding force that acts on the anti-slide pile and suggest a method for computing the prestressing force. In the method, the cable, anti-slide pile, and the rock-soil surrounding the pile below the slip surface are regarded as a whole and the prestressing force should be calculated according to the long-time load, while the effect of the short-time load should be considered in the bearing capacity design of the cable and pile. The computation results show that the method leads the anti-slide pile and the cable to be at an advantageous internal force condition and hence to improve the structure s safety.
On the base of existing methods for computing the cable s prestressing force in design of anti-slide pile with prestressed cable, we consider the change of horizontal sliding force that acts on the anti-slide pile and suggest a method for computing the prestressing force. In the method, the cable, anti-slide pile, and the rock-soil surrounding the pile below the slip surface are regarded as a whole and the prestressing force should be calculated according to the long-time load, while the effect of the short-time load should be considered in the bearing capacity design of the cable and pile. The computation results show that the method leads the anti-slide pile and the cable to be at an advantageous internal force condition and hence to improve the structure s safety.
2002, 10(3): 321-325.
The paper deals with the foundation treatment for both southern and northern slopes of a bridge in Pudong area. An deformation monitoring result make us to know that the effectiveness of different consolidation methods under a similar engineering-geological condition is different, and some useful conclusions were drawn .
The paper deals with the foundation treatment for both southern and northern slopes of a bridge in Pudong area. An deformation monitoring result make us to know that the effectiveness of different consolidation methods under a similar engineering-geological condition is different, and some useful conclusions were drawn .
2002, 10(3): 326-330.
In the analyses of slope stability aimed at securing engineering projects, a key is to identify potential sliding surfaces. For this purpose, we wrote out the two-dimensional and three-dimensional simulation programs, whose principles are briefly introduced in this paper. In the two-dimensional simulation four calculation models are proposed, while in the three dimensional simulation space, load and seepage effect are taken into account. This paper gives two simulation examples. The simulation result is basically in line with the measured result, especially in the shear strength of soil.
In the analyses of slope stability aimed at securing engineering projects, a key is to identify potential sliding surfaces. For this purpose, we wrote out the two-dimensional and three-dimensional simulation programs, whose principles are briefly introduced in this paper. In the two-dimensional simulation four calculation models are proposed, while in the three dimensional simulation space, load and seepage effect are taken into account. This paper gives two simulation examples. The simulation result is basically in line with the measured result, especially in the shear strength of soil.
2002, 10(3): 331-336.
A risk analysis method based on Bieniawskis RMR system was proposed. Firstly, variables which were acquired for the RMR classification system were obtained from field and laboratory investigation of the core samples . Secondly, distribution functions and parameters of all variables are determined using statistic method. Thirdly, 20000 RMR values have been obtained utilizing Monte Carlo method and the results are plotted . Finally, risk analysis can be made from above results. This method acquire good results in applied to the research on quality of rock masses in Runyang Yangze River Highway Bridge Project .
A risk analysis method based on Bieniawskis RMR system was proposed. Firstly, variables which were acquired for the RMR classification system were obtained from field and laboratory investigation of the core samples . Secondly, distribution functions and parameters of all variables are determined using statistic method. Thirdly, 20000 RMR values have been obtained utilizing Monte Carlo method and the results are plotted . Finally, risk analysis can be made from above results. This method acquire good results in applied to the research on quality of rock masses in Runyang Yangze River Highway Bridge Project .
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