2008 Vol. 14, No. 2

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ANALYSIS OF THE VOLUME STRAIN DATA FROM THE SHANDAN IN-SITU STRESS MONITORING STATION
PENG Hua, MA Xiu-min, JIANG Jing-jie
2008, 14(2): 97-108.
Abstract (128) HTML (74) PDF (475KB)(11)
Abstract:
The authors analyzed the volume strain data recorded from July 2007 to July 2008 in the Shandan in-situ stress monitoring station by using the statistical method, made a correlation of these seismic data with those recorded from other stations and studied the strain seismic waves, comseismic strain step and its contained physical significance, thus revealing the nature of the seismic strain waves.The data trends had pronounced anomalies.The effect of comseismic variation observed by the volume strain seismograph in the Shandan in-situ stress monitoring station was mainly the tensional step.
GENERAL CHARACTERISTICS OF 5.12 EARTHQUAKE-INDUCED GEOHAZARDS IN SICHUAN
ZHANG Yong-shuang, LEI Wei-zhi, SHI Ju-song, WU Shu-ren, WANG Xian-li
2008, 14(2): 109-116.
Abstract (197) HTML (90) PDF (697KB)(7)
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An earthquake of MS8.0 hit Wenchuan, Sichuan, on May 12, 2008 at 2:28 p.m.Beijing time, which brought serious disasters and great loss of property to the people of the earthquake-hit areas.Especially the serious consequence that the earthquake-induced geohazards in mountainous areas caused was unexpected.This paper mainly reports the primary investigation results of the earthquake-induced geohazards in some worst-hit mountainous areas near the epicenter in Sichuan, briefly describes the characteristics of development and harm of earthquake-induced geohazards such as landslide, rockfalls, debris flow, ground fissures and sand-soil liquation and presents some ideas about the development mechanisms of earthquake-induced geohazards and problems that need to be further studied.All these have certain significance for guiding the reconstruction of earthquake-hit areas and planning cities and towns in high-intensity areas.
COAL AND GAS OUTBURST RESEARCH:PRESENT STATE AND DIRECTION
SUN Ye, TAN Cheng-xuan, SUN Wei-feng, WANG Rui-jiang, WU Shu-ren, WANG Xi-hai, CHEN Qun-ce
2008, 14(2): 117-134.
Abstract (165) HTML (68) PDF (663KB)(10)
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Based on the research results and practical experience in coal and gas outbursts in the coal industry over the last nearly 200 years, the authors have basically understood the research concept and method, development process of the research, present research state and existing key problems and explored the possibility and feasibility of using the theory and method of geomechanics to perform coal and gas outburst research and solve the problems.
TECTONIC STABILITY ANALYSIS OF THE KAX RIVER HYDROELECTRIC PROJECT AREA
WANG Cheng-hu, ZHANG Yan-shan, XIONG Yu-zhen, KONG De-hu
2008, 14(2): 135-140.
Abstract (166) HTML (97) PDF (238KB)(9)
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This paper has studied the tectonic stability of a dam site for a large-scale hydroelectric project, and analyzed the regional geological tectonic setting, activity of faults, historical earthquakes, tectonic stress fields of the project area.The analysis indicates that the dam site of the hydroelectric candidate project lies in a relatively stable block of the tectonically active region, where the fault movement is rather weak and so is the regional tectonic movement.Therefore, this site can be controlled by engineering measures and is suitable to the construction of the hydroelectric project.
APPLICATION OF THE ANSYS SOFTWARE TO SOLVING COUPLING OF IN-SITU STRESS AND FLUID
WANG Lian-jie, SUN Dong-sheng, ZHOU Chun-jing, Wang Wei, ZHAO Wei-hua, WANG Hong-cai
2008, 14(2): 141-148.
Abstract (114) HTML (59) PDF (267KB)(10)
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The coupling of the in-situ stress and fluid is the research focus in recent years and also an important subject in research on rock and soil engineering and geology.So it has prominent significance to find out a simple method to solve the stress-fluid coupling equation.In this paper, a simple method of solving the stress-fluid coupling equation at certain boundary conditions is proposed based on the corresponding relation of the seepage equation of stress-fluid coupling and heat conduction equation and using the structural mechanical module and heat conduction module in the ANSYS software.The results obtained from the method are in good agreement with the theoretical solution and actual outcomes.
3D GEOLOGICAL MODELING OF COMPLEX LANDFORMS BASED ON FLAC3D
WANG Ji-lin, DING Chen-jian, WU Sheng-lin
2008, 14(2): 149-157.
Abstract (165) HTML (67) PDF (926KB)(10)
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With respect to the problem of numerical modeling for simulation in conditions of complex lan dforms and geological structure, the idea of modeling from the part to whole was put forward based on the FLAC3D platform.Using the primitive mesh shapes of brick and tetrahedron, a 3D model of the geologic body under complex landform conditions was constructed by means of computer programming.A lay ered continuous geological body was fitted up using the trend surface analysis and defined as different "groups".Thus a multi-layered 3D structure model of the geologic body was constructed.The fault plane in the geologic body was simulated by using interface.On that basis, combined with the trend surface analysis, the strata of the hanging wall and footwall of a fault were simulated.The authors consider that a 3D model of the geologic body with complex landforms and geological structure can be constructed in FLAC3D directly by using mathematical analysis and computer programming.
EFFECTS OF STRAIN-SOFTENING DILATANCY ON PROGRESSIVE DEFORMATIONS AND PRECURSORS TO FAILURE OF ROCK WITH INITIAL RANDOM IMPERFECTIONS
WANG Xue-bin
2008, 14(2): 158-167.
Abstract (126) HTML (67) PDF (424KB)(5)
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For rock specimens with initially random material imperfections in uniaxial plane strain compression, the effects of shear dilatancy on the failure precursors and deformational characteristics are modeled using FLAC.For compact rock elements exhibiting the linear strain-softening behavior after the occurrence of failure and then the ideal plastic behavior, the failure criterion is a composite MohrCoulomb criterion with tension cut-off.Imperfections undergo an ideal plastic behavior after the occurrence of failure.As axial strain increases, the number of failed elements inside the specimen increases till a constant, which increases with increasing dilation angle, is reached.At a much higher dilation angle, the calculated Poisson's ratio at the pre-peak time can be higher than 0.5;shear dilatancy occurs at the pre-peak time; the final volume of the deformed rock specimen is higher than the original volume.Shear strain localization leading to a relative sliding between adjacent blocks and shear dilatancy in shear bands are responsible for the volume dilation of the rock specimen with non-zero dilation angles.Rock specimens with higher dilation angles have more apparent precursors to failure through observing the shear strain increment and the number of failed elements at peak stress as well as the deviations of lateral strain, calculated Poisson's ratio and volumetric strain at the pre-peak time from linear states.The measured well-developed shear band inclination in the interior of rock specimens is closer to the Arthur theory and more scattered owing to the curved shear bands at lower dilation angles.
COMPREHENSIVE TESTS AND APPLIED STUDIES OF HYDRAULIC FRACTURING IN THE ROCK MASS OF THE YANGJIANG PUMPING STORAGE POWER STATION
WANG Hui-ming, WANG Zhu-jie, DAI Bing-guo
2008, 14(2): 168-175.
Abstract (194) HTML (113) PDF (275KB)(7)
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The surrounding rocks of the water tunnel of the Yangjiang pumping storage power plant are required to bear a maximum static pressure of 7.83 MPa; therefore, the state of in-situ stress, dead loadbearing capacity of surrounding rocks and high-pressure permeability are all essential data for the scientific design of the project.The measurement results show that the general characteristics of the present crustal stress field of the project area are as follows:the horizontal principal stress is the maximum principal stress, and the preferred orientation of the maximum horizontal principal stress is NW-WNW, the maximum principal stress of surrounding rocks of the plant buildings and high-pressure branch tunnel area is generally 14.5±0.5 MPa and the minimum principal stress is 9±0.5 MPa; the dead load-bearing capacity of surrounding rocks is 10-14 MPa; and the surrounding rocks are essentially impermeable at high pressures of 8-10 MPa.The results of those measurements of physical-mechanical parameters of surrounding rocks offer a reliable basis for the scientific design of the project.
FLUID INCLUSION STUDY OF THE SHAZHOU URANIUM OREFIELD IN THE XIANGSHAN DEPOSIT, JIANGXI
HUANG Xi-qiang, CHEN Zheng-le, WANG Ping-an, YANG Nong, ZHI Jian
2008, 14(2): 176-185.
Abstract (200) HTML (93) PDF (415KB)(7)
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Study of fluid inclusions in calcite, quartz and fluorite in the Shazhou deposit, Xiangshan uranium orefield, Jiangxi, indicates that::the homogenization temperatures of ore fluids ranged from 200 to 210℃ and from 230 to 260℃; the salinities ranged from 11.01 to 12.00% wt.% NaCl equivalent and from 18.01 to 20.00% wt.% NaCl equivalent; the average density was 0.94 g/cm3; the oreforming pressures ranged from 168.4×105 to 433.0×105 Pa with an average of 283.8×105 Pa.The oreforming depths estimated based on the relation between pressure and depth ranged from 0.561 to 1.443 km with an average of 0.946 km.According to the abovementioned, combined with an analysis of the composition of fluid inclusions and the stable isotope data, the authors conclude that the ore fluids of the Shazhou uranium deposit were mainly derived from meteoric water, mixed with small amounts of magmatic water and mantle-derived hydrothermal fluids.
METHOD FOR THE CONSTRUCTION OF THE GEOLOGICAL MAP DATABASE BASED ON MAPGIS——EXAMPLE FROM THE 1:1 M GEOLOGICAL MAP DATABASE OF CHINA
KE Xue, DING Xiao-zhong, HAN Kun-ying, JU Yuan-jing, PANG Jian-feng
2008, 14(2): 186-192.
Abstract (202) HTML (93) PDF (320KB)(8)
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With the rapid development of informationization and continuous advances in technology and theory in China, the establishment of the geological map database has become the current trend of development.The geological map database based on GIS is convenient for the storage, inquiry, analysis and updating of the geological data, thus laying a foundation for information sharing.Take for example the 1:1 M Geological Map Database of China, this paper introduces the method of building the geological map database based on MAPGIS in such aspects as mapping design, data preparation, data processing, projection conversion, map connection, database building and data examination and updating.