Study On Rockmass Joints Geometric Feature And Three-dimension Network Simulation

Rock discontinuity exists across rock mass widely,which seriously damage to continuity and integrity of rock mass. For this reason,it largely determines the mechanical, hydraulic、rock stability and distribution of groundwater of the rock mass. Therefore,structuralcondition of rock mass is the key to running high-level radioactive waste repositories reliably. Currently, at the stage of screening areas for HLW repository site, accurate description and effective analysis of geometry features of structure planes is fundamental job. Also, it is footstone for further research and evaluation.The main study objects of this paper are joints, faults, dykes and alteration zones based on two areas:Xichang Section,Beishan,Gansu province and Tianhu Section, Xinjiang province. They are bothpreselected areas of Chinese High Level Radioactive Waste. Based on research results of characteristics of structure planes、rock quality evaluation method and 3D joints network simulation, the relationship of fault to joint and geometry characteristic of jointed superiority trend are studied by means of field surveys, probability statistics and chart analysis, laboratory tests and numerical simulation. Furthermore, rock quality evaluation method and 3D joints network simulation are advanced. A great deal of joint data is obtained from joint survey in the vicinity of BS17, BS18, BS19 borehole of Xichang Section and Tianhu Section. In terms of field survey data, jointed advantages groups are determined with rose diagram analysis. According to probability analysis of joints,we calculate average distance between the advantage groups anddistribution of probability density. By means of theory of circular windowmethod,the mean trace length and mean trace midpoint density are calculated.On the basis of outcrops joint parameters of both sides of the fault,relationship between length of fault and widths of fault influence zone is studied according to different size、types of faults,and its generating geomechanics mechanis is described. Given structure plane of rock mass is the main channel of groundwater and radionuclide migration, a comprehensive evaluation index of structural plane- SCE is proposed. SCE can be used to evaluate completeness of rock mass and also partition rock mass by quality.According to one-to-one correspondence of joint trace and joint disc, therelationship of trace midpoint area density and the joint volume density is obtained. On the basis of joint geometry characteristic and its generating mechanics-mechanism, a 3-D "mathematic-mechanics" joint system model is developed. Based on the Monte Carlo method, the relationship of different joint sets is considered and the hierarchy of joint is described in the model.