1994 Vol. 2, No. 2
1994, 2(2): 1-8.
The Dashankou Hydropower Station on Kaiduhe River, Xinjiang,is located in an area with highly active tectonic movement.The field evidance shows that the Hongshuigou fualt cutting through the station exhibited multi-phase activity by the end of late Pleistocene,while the last faulting on the small fault F9 occurred before late Pleistocene.We analysed the samples of fault materials collected along these two faults by means of analysis of microstructures,quartz surface structures and TL dating.The results reveal that the main period of activity is from the end of Pliocene to Early Pleistocene,and obvious activity had not occured since Middle Pleistocene along the segment of the Hongshuigou fault in engineering site;while the upper limit of time of last faulting is 90 ka along the F9. The dam area is a relatively stable area in modern tectonic activity and is a perfect engineering site.
The Dashankou Hydropower Station on Kaiduhe River, Xinjiang,is located in an area with highly active tectonic movement.The field evidance shows that the Hongshuigou fualt cutting through the station exhibited multi-phase activity by the end of late Pleistocene,while the last faulting on the small fault F9 occurred before late Pleistocene.We analysed the samples of fault materials collected along these two faults by means of analysis of microstructures,quartz surface structures and TL dating.The results reveal that the main period of activity is from the end of Pliocene to Early Pleistocene,and obvious activity had not occured since Middle Pleistocene along the segment of the Hongshuigou fault in engineering site;while the upper limit of time of last faulting is 90 ka along the F9. The dam area is a relatively stable area in modern tectonic activity and is a perfect engineering site.
1994, 2(2): 9-17.
In present paper,according to the displacement values measured by using a multipoint dislacement guage in situ,in connection with the general deformation law and basic geological knowledge,the authors study the theory and method of inversion analysis and deduction of structure of rock mass around openning.The theory and method are tested and verified in engineering practice.
In present paper,according to the displacement values measured by using a multipoint dislacement guage in situ,in connection with the general deformation law and basic geological knowledge,the authors study the theory and method of inversion analysis and deduction of structure of rock mass around openning.The theory and method are tested and verified in engineering practice.
1994, 2(2): 18-28.
Engineering geological zonation and related evaluation of the Pearl River mouth basin are an important result of the UNDP Project CPR/85/044.Integrated studies of multi-disciplines indicate the surveyed area which covers the segments of continental shelf(Ⅰ) and slope(Ⅱ)can be divided into five subzones.The unfavourable engineering geological factors in Subzone Ⅰ1 are low soil strength,strong hydrodynamics and many geohazards such as buried channels,shallow gas.The potential geohazards and geological coastraints in SubzonesⅠ2 include shelf valleys,ancient shoals,sand domes and pockmarks on the seafloor,and differential sedimentary faults within the subbottom.The major geological constraints in Subzone Ⅰ3 are characterized by development of paleao-delta sedimentary system,complexity in lithology and stratigraphic structure,frequent earthquakes with stong intensity.In subzone Ⅱ1,seafloor instabilities include landslides,slumps, turbility currents and dense growing faults.The constraints for seafloor engineering in Subzone Ⅱ2 are principally steep topography and occurence of mud diapir. In this paper,all engineering geoloical problems mentioned above are discussed in detail and assessed through the aspect of geomorphy,siol property,slope stability and neotectonics.
Engineering geological zonation and related evaluation of the Pearl River mouth basin are an important result of the UNDP Project CPR/85/044.Integrated studies of multi-disciplines indicate the surveyed area which covers the segments of continental shelf(Ⅰ) and slope(Ⅱ)can be divided into five subzones.The unfavourable engineering geological factors in Subzone Ⅰ1 are low soil strength,strong hydrodynamics and many geohazards such as buried channels,shallow gas.The potential geohazards and geological coastraints in SubzonesⅠ2 include shelf valleys,ancient shoals,sand domes and pockmarks on the seafloor,and differential sedimentary faults within the subbottom.The major geological constraints in Subzone Ⅰ3 are characterized by development of paleao-delta sedimentary system,complexity in lithology and stratigraphic structure,frequent earthquakes with stong intensity.In subzone Ⅱ1,seafloor instabilities include landslides,slumps, turbility currents and dense growing faults.The constraints for seafloor engineering in Subzone Ⅱ2 are principally steep topography and occurence of mud diapir. In this paper,all engineering geoloical problems mentioned above are discussed in detail and assessed through the aspect of geomorphy,siol property,slope stability and neotectonics.
1994, 2(2): 29-37.
The extent and height of coal minigumduced overburden failure are significant basis for designing waterproofing coal/rock pillars of mining under water bodies and for the stability evalution of overburden above mining-out zone.Based on the theory of engineering geomechanics for rockmass,the failure mechanism and criteria of overburden are studied in this paper.Various factors such as engineering geological types and their composition,structure characteristics of rockmass,dip angle of strata,geological structure,ground stress and underground water,affecting on the height and regularities of developing overburden failure are analyzed in some detail.An engineering geological prediction method is presented and application cases are described.
The extent and height of coal minigumduced overburden failure are significant basis for designing waterproofing coal/rock pillars of mining under water bodies and for the stability evalution of overburden above mining-out zone.Based on the theory of engineering geomechanics for rockmass,the failure mechanism and criteria of overburden are studied in this paper.Various factors such as engineering geological types and their composition,structure characteristics of rockmass,dip angle of strata,geological structure,ground stress and underground water,affecting on the height and regularities of developing overburden failure are analyzed in some detail.An engineering geological prediction method is presented and application cases are described.
1994, 2(2): 38-47.
The closure behaviors of joint depend on the characteristics of composite morphology of joint principally and not morely depend on the morphologic characteristics of individual joint surfaces.In this paper after analysis of morphologic topographic characteristics of joint surfaces and composite morphology of joint a closure model for containing waviness in surface morphology is put forward.The composite morphology parameters of joint adapted in the model can reflect the influence of contact state and initial aperture on closure behavior of joint.It is confirmed by experiment that this closure model is closer to experiment results than the model that does consider the waviness in morphology of joint surfaces.
The closure behaviors of joint depend on the characteristics of composite morphology of joint principally and not morely depend on the morphologic characteristics of individual joint surfaces.In this paper after analysis of morphologic topographic characteristics of joint surfaces and composite morphology of joint a closure model for containing waviness in surface morphology is put forward.The composite morphology parameters of joint adapted in the model can reflect the influence of contact state and initial aperture on closure behavior of joint.It is confirmed by experiment that this closure model is closer to experiment results than the model that does consider the waviness in morphology of joint surfaces.
1994, 2(2): 48-53.
On the basis of fractal theory,the spatial fractal dimensions of landslides and water system in Zhangmu area are claculated by box-counting method in Tibet.The variation features of fractal dimensions are analysed.The results shows that the lower fractal dimension phenomena of different amplitude exist before high activity of a landslide.The activity climax period.The extent of landslides activities is different in a landslide area,where the variation of fractal dimensions of water system is evidently different in different measure scales.The authors also discuss the significance of fractal dimensions in prediction of landslides.
On the basis of fractal theory,the spatial fractal dimensions of landslides and water system in Zhangmu area are claculated by box-counting method in Tibet.The variation features of fractal dimensions are analysed.The results shows that the lower fractal dimension phenomena of different amplitude exist before high activity of a landslide.The activity climax period.The extent of landslides activities is different in a landslide area,where the variation of fractal dimensions of water system is evidently different in different measure scales.The authors also discuss the significance of fractal dimensions in prediction of landslides.
1994, 2(2): 54-65.
Destruction of statue rockmass by weathering in Baodingshan Grotto is becoming more and more serious day by day.Such problem is a common one for carved stone spots.Based on site investigation and research work,the reasons for weathering destruction to rockmass were clarified in detail in respect of external envionment and internal actions of rock-mass.It can be served as basis for adapting measures of protection for carved stone spots against weathering.
Destruction of statue rockmass by weathering in Baodingshan Grotto is becoming more and more serious day by day.Such problem is a common one for carved stone spots.Based on site investigation and research work,the reasons for weathering destruction to rockmass were clarified in detail in respect of external envionment and internal actions of rock-mass.It can be served as basis for adapting measures of protection for carved stone spots against weathering.
1994, 2(2): 66-75.
After discussion of the sampling technique by using a fixed piston thin wall sampler an analysis is given on the test resut of soft clay from Harbours of Lianyungang and Chiwan,and the Guang-Shen Express Highway in this paper.It is indicated that the mechanical properties of solf clay determined in laboratory are influenced remarkably by the disturbance of soil samples,but the influence of sampling disturbance on the value of physical parameters is not significant.It is convincingly ghown by the study that high quality samples can be obtained with the thin wall sampler provided that the sampling is done strictly according to the operating instruction,while the samples obtained with conventional thick wall open drive tube sampler are often seriousjy disturbed.
After discussion of the sampling technique by using a fixed piston thin wall sampler an analysis is given on the test resut of soft clay from Harbours of Lianyungang and Chiwan,and the Guang-Shen Express Highway in this paper.It is indicated that the mechanical properties of solf clay determined in laboratory are influenced remarkably by the disturbance of soil samples,but the influence of sampling disturbance on the value of physical parameters is not significant.It is convincingly ghown by the study that high quality samples can be obtained with the thin wall sampler provided that the sampling is done strictly according to the operating instruction,while the samples obtained with conventional thick wall open drive tube sampler are often seriousjy disturbed.
1994, 2(2): 76-83.
Experimental data shows that the pores 0.02 and 0.08mm in diameter built on stilts are the main factor causing extreme intense and intense collapsibility, support pores 0.008 and 0.02mm in diameter are main factor carusing moderate and weak collapsibility.The different combinaction of pores results in different grades of loess collapse,the con spicuous characteristics of loess of extreme intense and intense collasibility are that the pores built on stilts occur in the form of meshes.The reduced amount of pores after collape is between 0.8-20%.Macropores also behave collapsibility to a certain extent,the collasibility of loess was formed in the porcess of soil forming in arid and semiaridareas.
Experimental data shows that the pores 0.02 and 0.08mm in diameter built on stilts are the main factor causing extreme intense and intense collapsibility, support pores 0.008 and 0.02mm in diameter are main factor carusing moderate and weak collapsibility.The different combinaction of pores results in different grades of loess collapse,the con spicuous characteristics of loess of extreme intense and intense collasibility are that the pores built on stilts occur in the form of meshes.The reduced amount of pores after collape is between 0.8-20%.Macropores also behave collapsibility to a certain extent,the collasibility of loess was formed in the porcess of soil forming in arid and semiaridareas.
1994, 2(2): 84-88.
In this paper a summarizing is made on the experience and lessons in practial engineering,and the main problems on supporting of deep pit slope for tall building and their solution are suggested.
In this paper a summarizing is made on the experience and lessons in practial engineering,and the main problems on supporting of deep pit slope for tall building and their solution are suggested.
1994, 2(2): 89-96.
The reliability of geological parameters for design of engineering projects is direct important for the economic cost and safety of an engineering project construction.This paper deals with a method for evaluation of precision of engineering geological data,including data optimization,determining optimum sample volue,and reliability of calculation.The target value estimates and their confidence levels are given for different design stages.
The reliability of geological parameters for design of engineering projects is direct important for the economic cost and safety of an engineering project construction.This paper deals with a method for evaluation of precision of engineering geological data,including data optimization,determining optimum sample volue,and reliability of calculation.The target value estimates and their confidence levels are given for different design stages.