2006 Vol. 12, No. 2

Display Method:
DEVELOPING LI SIGUANG'S “SAFETY ISLAND” THOUGHT AND MAKING SERIOUS EVALUATION AND RESEARCH ON REGIONAL CRUSTAL STABILITY IN AREAS OF ENGINEERING WORKS
YI Ming-chu, HU Hai-tao, YIN Yue-ping, PENG Hua
2006, 12(2): 105-118.
Abstract (192) PDF (719KB)(9)
Abstract:
In order to develop Li Siguang's academic thoughts,this paper reviews the creation process of Li Siguang's "safety island" thought,briefly introduces the development process of the thought from "safety islands and stable masses" to "regional crustal stability" and summarizes the main factors and methods for regional crustal stability evaluation.Finally the paper present several major problems for strengthening and developing his "safety island" thought.Great attention should be paid to these problems,so the study of this field may become more mature.
HUGE DISASTER RISK AND PREVENTION IN CHINA
ZHANG Ye-cheng, MA Zong-jin, GAO Qing-hua, ZHANG Li-hai, LIU Feng-min
2006, 12(2): 119-126.
Abstract (158) PDF (465KB)(9)
Abstract:
Huge disasters refer to the natural disasters that cause the huge loss of life and property and have serious impact on social and economic development.Huge disasters in China include extraordinary floods,large earthquakes,exceedingly large storm tides and sustained droughts over large tracts.Huge disasters have occurred in 18 different years since the founding of the People's Republic of China.The root-causes for frequent occurrence of huge disasters are complex and highly varied natural conditions,intense and abnormal dynamic activities,weak disaster reduction infrastructure and insufficient huge disaster prevention ability.Huge disasters still seriously threaten the national safety,society and economy in the future.It is estimated that 11 high-risk areas are distributed in eastern coastal areas and a part of central areas in China.The countermeasures of huge disaster prevention include raising people's awareness,enhancing study,establishing a management system and an early-warning system,working out an emergence plan and strengthening international exchange.
DANGER ASSESSMENT OF EARTHQUAKE-INDUCED GEOLOGICAL DISASTERS IN CHINA
LIU Feng-min, ZHANG Li-hai, LIU Hai-qing, ZHANG Ye-cheng
2006, 12(2): 127-131.
Abstract (204) PDF (267KB)(12)
Abstract:
Earthquake-induced secondary geological disasters include avalanches,landslides,caving-in,ground cracks and liquefaction of sand.The earthquakes of magnitudes > 5 and intensity > VI may lead to occurrence of various scales of geological disasters.The higher the magnitude and intensity are,the secondary geology disaster will be more serious.Based on the extent and occurrence conditions of secondary geological disasters induced by historic earthquakes in China,the danger assessment has been made with the city,prefecture and meng(league) as the unit.The high and moderate danger areas are mainly distributed in the Shaanxi-Gansu-Ningxia-Sichuan-Chongqing-Yunnan-Tibet region in the central part of China,forming a nearly NE-trending high danger zone,and all other remaining areas are low danger areas.
CHARACTERISTICS OF SEGMENTS OF SURFACE RUPTURES OF STRONG EARTHQUAKES ALONG THE EAST KUNLUN ACTIVE FAULT ZONE
JIANG Wa-li, XIE Xin-sheng
2006, 12(2): 132-139.
Abstract (180) PDF (432KB)(18)
Abstract:
The East Kunlun active fault zone is an up to 1000 km long active fault zone in the interior of the Qinghai-Tibet Plateau.Four strong earthquakes of MS ≥ 7.0 have occurred along the fault zone during the past 100 years.The latest one was the Kunlun Mountain Pass earthquake of MS=8.1 in 2001.The paper discusses the characteristics of segments of surface ruptures due to strong earthquakes along the fault zone and the stability or instability of the obstacles at the ends of the surface ruptures of strong earthquakes based on the geometric distribution,rates of activities and distribution of surface ruptures of historical strong earthquakes and paleo-earthquakes along the fault zone and by an integrated analysis of previous data.It is emphasized that the coincidence and difference between the geometrical distribution of the fault zone and present segmentation of the surface ruptures should be understood from the process of evolution of the zone.In addition,the future dangerous segments of ruptures due to strong earthquakes along the zone are discussed.
NUMERICAL MODELING OF THE PRESENT TECTONIC STRESS FIELD IN THE CENTRAL QINGHAI-TIBET PLATEAU
WANG Lian-jie, WU Zhen-han, WANG Wei, SUN Dong-sheng
2006, 12(2): 140-149.
Abstract (215) PDF (379KB)(15)
Abstract:
Considering crustal rocks as viscous fluids,the tectonic stress field and velocity field of the central segment of the Qinghai-Tibet Plateau are modeled by using the finite element method.The results of modeling indicate that the Qinghai-Tibet Plateau is generally displaced toward the north and east.The velocity of north-directed displacement is highest in the south and gradually decreases form south to north.The velocity of east-directed displacement is highest near the Tanggula fault and gradually decreases toward the south and north sides,showing an "extrusion phenomenon".The maximum principal stress is oriented mainly in a NNW direction in the south and in a NNE direction in the north,generally in a N-S direction.Comparison of the modeling results with the results of tectonic survey and earthquake activity and GPS measurements shows that they are in good agreement.This well reveals the characteristics of tectonic activity,intensity of fault activity and driving mechanism of east-directed displacement in the Qinghai-Tibet Plateau.The present activity of the Qinghai-Tibet Plateau is the results of combined action of northward push and compression of the Indian plate and eastward flow of deep materials.
LANDSLIDE STABILITY ANALYSIS BY THE 3D ELASTIC PLASTIC CONTACT FINITE ELEMENT ALGORITHM
XU Jian-cong, SHANG Yue-quan, TIAN Xiao-juan
2006, 12(2): 150-159.
Abstract (198) PDF (607KB)(8)
Abstract:
In order to evaluate accurately the stability of slopes of rock debris and soil,the integral stability coefficient of a debris and soil landslide was computed and its stability was analyzed through the data collection,arrangement and analysis,site engineering-geological investigation and exploration and indoor and outdoor physical mechanics tests and by adopting the 3D contact elastic-plastic FEM algorithm.When using the 3D elastic-plastic contact FEM strength reduction method to compute the stability coefficient of debris-soil landslides,the space effect of the sliding mass may be considered in order the calculation results to be more accurate.During the deformation,disintegration and failure of debris-soil landslides,in space the plastic strain of the sliding mass and shear strength of the rock or soil mass on a sliding plane are different.The method for computing the stability coefficient of the debris-soil landslide of a 2D section by extracting the contact frictional stress on the sliding surface on the basis of the computation result by the 3D elastic-plastic contact FEM algorithm is relatively suited to the stability analysis and evaluation of this type of landslide and can reflect the actual state of the landslide relatively objectively and accurately.
FRACTURE SYSTEM AND ITS EFFECT ON THE HYDROPOWER PROJECT IN THE GOUPITAN AREA, GUIZHOU
CHEN Wen-li, HOU Guang-jiu, YIN Chun-ming, XIANG Neng-wu, WANG Ling-zhan
2006, 12(2): 160-165,159.
Abstract (136) PDF (380KB)(30)
Abstract:
Fractures in large-scale engineering works such as dams and tunnels have long gained attention because they concern safety problems of engineering works such as the strength of rock masses.There mainly occur carbonate rocks with minor clastic rocks at the dam site of the Goupitan Hydropower Station,Wujiang,Guizhou,and the NE,NW,N-S and E-W sets of structural fractures may be recognized in the rock sequences.However,80 percent of the fractures have been healed by three phases of calcite veins,thus greatly reducing water permeability and increasing the strength of rocks.Some fractures have not been filled or re-opened after filling,of which bedding-parallel slip fractures are throughgoing to a certain extent,to which attention should be paid in engineering works.
3D NUMERICAL SIMULATION OF THE ANCHOR EFFECT OF PRESTRESSED CABLES AND ITS ENGINEERING APPLICATION
ZHANG Si-feng, ZHOU jian, SONG Xiu-guang, LI Shu-cai
2006, 12(2): 166-173.
Abstract (234) PDF (571KB)(14)
Abstract:
Prestressed cable anchor technology has been widely used in many fields of geotechnical reinforcement engineering.However,the research on the reinforcement mechanism of prestressed anchorage is still at an exploratory stage.Based on the fast Lagrangian analysis method(FLAC-3D),the stress,deformation and failure mechanisms of the anchorage segment,free segment and anchor pier under the effect of the single or multi-cable anchor system have been analyzed through 3D numerical modeling and some influence factors of shear stress distribution along the anchorage segment have also been discussed.On that basis,some useful conclusions are drawn,which can provide a reference for the engineering design and theoretical study.These research results prove to be effective through engineering practice.
ANALYSIS OF THE FORMATION SYSTEM OF THE PRESENT TECTONIC STRESS FIELD IN THE HEAD AREA OF THE THREE GORGES RESERVOIR
LI Xi-guang, YAO Yun-sheng, ZENG Zuo-xun, LIU Li-lin
2006, 12(2): 174-181.
Abstract (175) PDF (495KB)(7)
Abstract:
The present tectonic stress field in the head area of the Three Gorges reservoir was systematically analyzed and verified in the geological,seismological,deformation and in situ stress contexts and checked by numerical modeling.The authors think that the present tectonic stress field in the study area belongs to a pure shear system,i.e.the superimposition of the NE-SW principal compressional stress from the west is superimposed by the WNW-ESE principal tensional stress resulting from extension of the Jianghan-Dongting basin.The axes of the two stresses intersect nearly perpendicularly to each other;so they can act as the principal compressive stress(σ1) and the principal tensional stress(σ3) of present tectonic stress field in the study area respectively.
HYDROFRACTURING IN-SITU STRESS MEASUREMENTS OF THE WATER DIVERSION AREA IN THE FIRST STAGE OF THE SOUTH-NORTH WATER DIVERSION PROJECT (WESTERN LINE)
PENG Hua, CUI Wei, MA Xiu-min, LI Jin-suo
2006, 12(2): 182-190.
Abstract (148) PDF (405KB)(13)
Abstract:
This paper introduces the principle and method of hydrofracturing insitu stress measurement and its applications in the south-north water diversion project of the western line.The magnitude and direction of the principal stress were measured along the line of the water diversion project and their mutual relation and distribution characteristics were analyzed.The results show that horizontal principal stress is dominant in the present crustal stress field,indicating a reversed fault state.Because the(Hmax/σV) value is higher,the tectonic activity in the area is intense.The principal compressional stress is generally northeast-directed and intersects with the regional tectonic line at an acute angle.Therefore,it is the main dynamic force for the transpressional sinistral movement of most regional faults.Moreover,the possibility of rock bursts in the deep tunnels is analyzed.These provide reliable data for the prevention and control of hazards in tunnels and the optimized design of various diversion lines for the south-north water diversion project.
MEASUREMENTS OF IN-SITU STRESS IN THE PUSHIHE HYDROPOWER STATION, LIAONING
WU Man-lu, LI Guo-jun, LIAO Chun-ting, DONG Cheng
2006, 12(2): 191-196.
Abstract (211) PDF (269KB)(5)
Abstract:
In-situ stress measurements were made in a survey tunnel using the hollow inclusion stress gauge in order to gain knowledge of the present stress state of the Pushihe hydropower station.A total of five in-situ stress-measuring sites were deployed and many measurements were made at each measuring sites.The calculation and integrated calculation of measurement results from the five sites were performed respectively by using the least squares.The results show that:the maximum principal stress is nearly horizontal and oriented in a N79°W direction,with a stress magnitude of 7.1 MPa.Although the measurement results of different segments of the measuring sites show certain deviations mainly due to the structural conditions of rock masses at different sites,the preferred orientation of the maximum principal stress is relatively prominent.Finally,based on the measurement results,the characteristics of the present stresses in the hinge area of the hydropower station are analyzed and some suggestions for the engineering design are presented.
IN SITU STRESS MEASUREMENT AND ITS APPLICATION IN THE PRE-FEASIBILITY STUDY OF AN UNDERGROUND OIL RESERVOIR IN CHINA
HOU Yan-he, SUN Wei-feng, CHEN Qun-ce, WANG Bao-jun, CHEN Shao-nan
2006, 12(2): 197-202.
Abstract (134) PDF (238KB)(8)
Abstract:
Hydrofracturing in situ stress measurements were used to determine in situ stress states of two drill holes for the pre-feasibility study of an underground reservoir at an engineering site in China.Both the maximum and minimum horizontal principal stresses(SH and Sh) are by far greater than the vertical stress(Sv) at the same depth,and the SH and Sh are higher than the normal stress state at the depth range,with a relation of SH > Sh > Sv.The maximum horizontal principal stress direction is nearly(E-W),which is in accord with the general direction of the regional maximum horizontal principal stress determined by measuring points in surrounding areas.The authors suggest that the long axis of the underground reservoir should be oriented in a nearly E-W direction in the future,and the in situ stress state,rock mass structure and rock strength will in the main ensure the rock mass stability.
CAUSE ANALYSIS AND QUANTITATIVE ZONATION OF MUDFLOW HAZARDS ALONG THE RAWU-LUNANG SECTION, SICHUAN-TIBET HIGHWAY
DING Ji-xin, YANG Zhi-fa, SHANG Yan-jun
2006, 12(2): 203-210,226.
Abstract (186) PDF (540KB)(9)
Abstract:
Unique geological,geomorphic,hydrological and climatic conditions cause various kinds of mountainous hazards,especially very serious mudflow hazards,to occur frequently in the Rawu-Lunang section,Sichuan-Tibet Highway.On the basis of previous research and the authors' field investigations,it is thought that the complex geological structures,strong crust movements and rivers erosions,frequent earthquakes,abundant loose deposits,favorable geomorphology,well-developed modern glaciers and plentiful precipitation are the principal causes of triggering frequent mudflows in the study area.For the purpose of more effective disaster prevention and reduction,the rock engineering system(RES) method is adopted to make a quantitative zonation of mudflows in the study area.By comparing the quantitative mudflow zonation with the preliminary qualitative zonation and distribution of mudflows,it is verified that the quantitative mudflow zonation method is correct and feasible.
RISK EVALUATION OF AVALANCHE, LANDSLIDE AND MUDFLOW HAZARDS IN THE UPPER REACHES OF THE YELLOW RIVER
ZHANG Chun-shan, LI Guo-jun, ZHANG Ye-cheng, MA Yin-sheng
2006, 12(2): 211-218.
Abstract (194) PDF (488KB)(12)
Abstract:
Based on field geological investigations of avalanches,landslides and mudflows in the upper reaches of the Yellow River,the authors determined the main influence factors and index system of the hazard risk evaluation and made risk evaluation with the county(city or qi) as a unit.There are a total of 116 units in the study region and the geological hazard risk is divided into 5 grades.There are 3 high risk units,8 relatively high risk units,24 moderate risk units is three,54 relatively low risk units and 27 low risk units.The results of risk evaluation indicate that the risk grades of avalanche,landslide and mudflow hazards differ greatly in different area of the region.The general distribution pattern is as follows:the risk is higher in the central area and lower in the north and south.The risk indices show that the risk indices of some risk units are very close to the critical value,and once the dangerous conditions and vulnerable conditions change,the risk grades of geological hazards would change accordingly.Therefore during the development of western China,whether for mineral exploration and mining or for various engineering operations,we should pay attention to environmental protection so as to avoid aggravation of geological hazards.
FORMATION CONDITIONS OF SLOPE TYPE MUDFLOW IN NINGSHAAN COUNTY, SOUTHERN SHAANXI,AND ITS INDUCING MECHANISM
YANG Wei-min, WU Shu-ren, ZHANG Yong-shuang, ZHANG Chun-shan, SUN Wei-feng
2006, 12(2): 219-227.
Abstract (183) PDF (595KB)(8)
Abstract:
The occurrence of slope mudflow is a process in which a landslide first occurs and then rapidly changes into mudflow.It has some properties of landslide and mudflow concurrently.The slope mudflow around the seat of Ningshaan County occurs on a steep slope of Middle Devonian strata.The eluvial soils on slopes where surface flow occurs are mainly clayey soils with some blocks or debris.They have good grading distribution and a thin soil horizon.The clay minerals in the eluvial soils consist of illite/montmorillonite,illite and kaolinite with low and intermediate dilatability,so their permeability is low or very low.When rainstorms persist,such soils will start to slide down the slope and be eroded,and furthermore,they rush down and form slurry,thus giving rise to slope mudflow.The canyons of slope mudflow are shallow and wide and mostly occur downslope,and sometimes those that obliquely intersect the slope direction but are parallel to the strike of the strata are also seen.They are embryos of canyon type mudflow.Therefore,it is necessary to study the dynamic features of slope type mudflow to provide a scientific basis for early-warning of mudflow disasters.
MAIN GEOHAZARD TYPES AND THEIR OCCURRENCE CHARACTERISTICS ALONG THE YUNNAN-TIBET RAILWAY IN NW YUNNAN
GUO Chang-bao, LEI Wei-zhi, ZHANG Yong-shuang, LIU Jing-ru
2006, 12(2): 228-235.
Abstract (151) PDF (692KB)(9)
Abstract:
The Yunnan-Tibet Railway in NW Yunnan is located at the transitional position of the southeastern Qinghai-Tibet Plateau to Yunnan-Guizhou Plateau,where landforms are complex,valleys are deeply incised,neotectonic movement is very intense and earthquakes occur frequently.The precipitation in the area is mainly recorded in May to October,when the rainfall is high and centralized.Because of the complex geological environment,combined with rain,human activities and other exterior factors,the area becomes an area of repeated occurrence of geohazards such as landslides,debris flow and avalanches,which often cause traffic interruption,destroy houses and cause casualties.On the basis of field geological investigations,the authors focus on the main geohazard types and their occurrence characteristics along the Yunnan-Tibet railway in NW Yunnan,which have important theoretical and practical significance for mitigating and preventing geohazards such as landslides,debris flows and avalanches that the railway might suffer.
A NEW METHOD FOR CHOOSING ZONATION INDICATORS OF MUDFLOW DANGER DEGREES BASED ON THE ROUGH SET THEORY
KUANG Le-hong, XU Lin-rong, LIU Bao-shen, YAO Jing-cheng
2006, 12(2): 236-242.
Abstract (157) PDF (311KB)(6)
Abstract:
In view of the deficiency in methods for choosing zonation indicators of mudflow danger degrees,a new method for choosing zonation indicators of mudflow danger degrees is put forward based on the rough set theory in this paper.Firstly,according to the environmental conditions of forming mudflows,an indicator choice system is established.Then the indicators for choice are discretized by indicator grading.Finally,based on the discernable matrix of the rough set,a core set of the indicators is found and the representative indicators are sieved out.The examples show that this method is easy to operate and considers both representativeness and comprehensiveness.
RAILWAY LOCATION IN A MOUNTAINOUS ENVIRONMENT IN AREAS OF ACTIVE STRUCTURES
QING San-hui, HUANG Run-qiu, LI Dong, JIANG Liang-wen
2006, 12(2): 243-251.
Abstract (117) PDF (515KB)(10)
Abstract:
Location of line in a mountainous environment in which active structures are well developed is a major engineering-geological problem concerned in railway and highway construction.In light of a study of the location of the Yu-Meng section of the newly built Kun-He Railway in southwestern China,the paper discusses the regional characteristics of internal and external dynamic geological processes and major engineering-geological problems such as the geological environment,neotectonic movement and earthquakes,active faults and seismic risks and mountainous hazards,and demonstrates and compares the optimized schemes of line orientation based on the engineering geological conditions and economic and technical aspects.This study may be used as reference for the railway and highway location in mountainous areas with a similar regional geological environment.
TIME EFFECT ANALYSIS OF ZONAL DISINTEGRATION OF HIGH IN-SITU STRESS SURROUNDING ROCKS AND STUDY OF RELEVANT PARAMETERS BASED ON THE CREEP INSTABILITY THEORY
LI Ying-jie, PAN Yi-shan, ZHANG Meng-tao
2006, 12(2): 252-260.
Abstract (126) PDF (411KB)(7)
Abstract:
It takes some time to form the phenomenon of zonal disintegration of surrounding rocks with high in situ stress,but the time needed is not too long.The creep theory is used to analyze the time effect of zonal disintegration of rocks and deduce the constitutive equation and creep equation of the improved Nishibara rheological model which can describe the third(accelerated) creep stage.On that basis,we can find the fracture zone radius(the distance from the fracture zone to the center of a tunnel) formula during the zonal disintegration of rocks.
COASTAL EROSION AND ITS MAIN CAUSE IN THE QINHUANGDAO AREA
ZHANG Li-hai, LIU Feng-min, LIU Hai-qing, ZHANG Ye-cheng, YU Dao-yong
2006, 12(2): 261-264,273.
Abstract (164) PDF (221KB)(9)
Abstract:
The paper analyzes coastal erosion and silting up in the Qinhuangdao area and discusses the constraints on coastal erosion and silting and their harm to coastal resources and environment based on information obtained from on-site investigation.The main conclusions are as follows:in the past 50-odd years,the 123.5km long coastline of Qinhuangdao has undergone six activities of erosion and silting up in different forms,of which the 82.69km long coastline has undergone erosion to various degrees,accounting for 67% of its total.Besides the storm tide impact,the main causes for coastal erosion are due to the continued decrease of material supply and manual extraction of sand and gravel.Coastal erosion can seriously destruct tourism resources and land resources and aggravate invasion of seawater besides threatening the safety of coastal engineering facilities.
SOME PROGRESS IN THE STUDY OF SUDDEN GEOLOGICAL HAZARDS
WU Shu-ren
2006, 12(2): 265-273.
Abstract (212) PDF (539KB)(7)
Abstract:
The whole world and researchers engaged in geological hazard prevention and control were shocked by the mudflow hazard occurring in Southern Leyte,central Philippin,e on February 17,2006,which caused more than 1000 deaths and missing.In order to introduce the status quo and progress in the study of such sudden geological hazards in various countries of the world,the paper attempts to introduce briefly the recent progress in prediction,monitoring,early-warning and risk assessment of sudden geological hazards from the recent progress and new information presented by the 32nd International Geological Conference and the international Conference on Landslide Risk Assessment and Management,combined with the State Medium-and Long-term Program on Science and Technology Development of China and the early-stage strategic research report on geological hazards in China in the Medium-and Long-term Program on Science and Technology Development of the Ministry of Land and Resources of China.
APPLICATION OF GEOGRAPHICAL INFORMATION SYSTEM (MAPGIS) IN GEOLOGICAL MAP PRODUCTION
LI Yue-hui
2006, 12(2): 274-278.
Abstract (169) PDF (548KB)(5)
Abstract:
With the wide application of the computer technique in various areas,the map,as the final form of expression of the geological research results,becomes more and more important.This paper introduces the application of the geographical information system(MapGis) in geological map production.By using MapGis,the map-producing method,form of expression and information use have been greatly improved and can better serve the users.