导水裂隙带高度研究方法概述   总被引：23，自引：0，他引：23  

王双美 《水文地质工程地质》2006,33(5):126-128

导水裂隙带高度的确定是水下采煤工作之重点，目前并没有一个完全可以精确确定的方法，主要的研究方法有经验公式法、物理模拟、数值模拟和现场实测。单靠其中的一种也不能确定，将几种方法相互结合则是准确得到导水裂隙带高度计算方法的重要途径。  相似文献   

招远黄埠岭金矿断裂构造性质及其控岩控矿作用   总被引：1，自引：0，他引：1  

杨斌  李守生  孙林  覃鹏 《矿产与地质》2006,20(3):211-213

黄埠岭金矿主矿体产于灵北断裂带主断裂上盘次级断裂中,根据7号和10号矿体旁侧小角度斜交剪节理与矿体锐夹角指向的判断,控矿断裂具左旋性质。根据7号矿体旁侧节理统计及共轭剪节理产状的分析,黄埠岭矿区含矿断裂形成的最大主压应力方向为30°∠37°。NE向次级断裂是成矿前煌斑岩脉侵位的重要空间,也是主要的容矿构造。灵北主断裂带则主要扮演了一种导矿构造的作用。  相似文献   

GIS技术在勉略阳地区多金属找矿预测上的研究与应用     

李春兰  向婷婷  毛小贤 《矿产与地质》2006,20(4):507-512

利用现代化计算工具，用MAPGIS地理信息系统软件的空间分析模块，对勉略阳地区化探异常进行信息处理，通过信息提取、信息关联、信息综合等信息处理过程，挖掘各种异常信息，定量圈定不同类型化探异常，并在此基础上进行初步成矿预测。  相似文献   

Common-ray tracing and dynamic ray tracing for S waves in a smooth elastic anisotropic medium   总被引：1，自引：0，他引：1  

L. Klimeš 《Studia Geophysica et Geodaetica》2006,50(3):449-461

Anisotropic common S-wave rays are traced using the averaged Hamiltonian of both S-wave polarizations. They represent very practical reference rays for calculating S waves by means of the coupling ray theory. They eliminate problems with anisotropic-ray-theory ray tracing through some S-wave slowness-surface singularities and also considerably simplify the numerical algorithm of the coupling ray theory for S waves. The equations required for anisotropic-common-ray tracing for S waves in a smooth elastic anisotropic medium, and for corresponding dynamic ray tracing in Cartesian or ray-centred coordinates, are presented. The equations, for the most part generally known, are summarized in a form which represents a complete algorithm suitable for coding and numerical applications.  相似文献   

Fluctuation responses of saturated porous media subjected to cyclic thermal loading     

Bing Bai   《Computers and Geotechnics》2006,33(8):396-403

Normalized, coupled governing equations for one-dimensional thermal consolidation problems are established. The non-dimensional coefficients of thermal consolidation and thermal diffusivity are defined accordingly. An analytical solution is deduced by using the Laplace transform and the Gauss–Legendre method of Laplace transform inversion. The responses of saturated porous media subjected to cyclic thermal loading are studied. The evolution of temperature, pore pressure and displacement from instantaneous state to quasi-steady state, with elapsed time, are analysed. The characteristics of cyclic fluctuation and the attenuation of the field variables with increased depth are also analysed. The influences of the permeability of media on thermal responses are discussed.  相似文献   

Hydro-geomechanical modelling of seal behaviour in overpressured basins using discontinuous deformation analysis     

M. Rouainia  H. Lewis  C. Pearce  N. Bicanic  G.D. Couples  M.A. Reynolds 《Engineering Geology》2006,82(4):222-233

A coupled hydro-geomechanical modelling environment, developed to evaluate the coupled responses of fluid flow in deforming discontinuous media, is described. A staggered computational framework is presented, where the two simulations tools, HYDRO and DDA, communicate via the mapping of an equivalent porosity (and related permeabilities) from the rock system to the fluid phase and an inverse mapping of the pressure field. Several algorithmic and modelling issues are discussed, in particular the computational procedure to map the current geometry of the discontinuous rock blocks assembly into an equivalent porosity (and permeability) field. A generic, geometrically simple, overpressured reservoir/seal system is analysed for illustration. Further examples investigate discontinuous, fractured configurations in flexure causing a degree of spatial variability in the induced stresses. Model predictions show that the combination of hydraulic and mechanical loads causes a dilational opening of some pre-existing fractures and closure of others, with strong localisation of the modified flow pattern along wider fracture openings.  相似文献   

Calculating the effective permeability of sandstone with multiscale lattice Boltzmann/finite element simulations     

Joshua A. White  Ronaldo I. Borja  Joanne T. Fredrich 《Acta Geotechnica》2006,1(4):195-209

The lattice Boltzmann (LB) method is an efficient technique for simulating fluid flow through individual pores of complex porous media. The ease with which the LB method handles complex boundary conditions, combined with the algorithm’s inherent parallelism, makes it an elegant approach to solving flow problems at the sub-continuum scale. However, the realities of current computational resources can limit the size and resolution of these simulations. A major research focus is developing methodologies for upscaling microscale techniques for use in macroscale problems of engineering interest. In this paper, we propose a hybrid, multiscale framework for simulating diffusion through porous media. We use the finite element (FE) method to solve the continuum boundary-value problem at the macroscale. Each finite element is treated as a sub-cell and assigned permeabilities calculated from subcontinuum simulations using the LB method. This framework allows us to efficiently find a macroscale solution while still maintaining information about microscale heterogeneities. As input to these simulations, we use synchrotron-computed 3D microtomographic images of a sandstone, with sample resolution of 3.34 μm. We discuss the predictive ability of these simulations, as well as implementation issues. We also quantify the lower limit of the continuum (Darcy) scale, as well as identify the optimal representative elementary volume for the hybrid LB–FE simulations.  相似文献   

The Development of a new Numerical Modelling Approach for Naturally Fractured Rock Masses   总被引：1，自引：3，他引：1  

R. J. Pine  J. S. Coggan  Z. N. Flynn  D. Elmo 《Rock Mechanics and Rock Engineering》2006,39(5):395-419

Summary. An approach for modelling fractured rock masses has been developed which has two main objectives: to maximise the quality of representation of the geometry of existing rock jointing and to use this within a loading model which takes full account of this style of jointing. Initially the work has been applied to the modelling of mine pillars and data from the Middleton Mine in the UK has been used as a case example. However, the general approach is applicable to all aspects of rock mass behaviour including the stress conditions found in hangingwalls, tunnels, block caving, and slopes. The rock mass fracture representation was based on a combination of explicit mapping of rock faces and the synthesis of this data into a three-dimensional model, based on the use of the FracMan computer model suite. Two-dimensional cross sections from this model were imported into the finite element computer model, ELFEN, for loading simulation. The ELFEN constitutive model for fracture simulation includes the Rotating Crack, and Rankine material models, in which fracturing is controlled by tensile strength and fracture energy parameters. For tension/compression stress states, the model is complemented with a capped Mohr-Coulomb criterion in which the softening response is coupled to the tensile model. Fracturing due to dilation is accommodated by introducing an explicit coupling between the inelastic strain accrued by the Mohr-Coulomb yield surface and the anisotropic degradation of the mutually orthogonal tensile yield surfaces of the rotating crack model. Pillars have been simulated with widths of 2.8, 7 and 14 m and a height of 7 m (the Middleton Mine pillars are typically 14 m wide and 7 m high). The evolution of the pillar failure under progressive loading through fracture extension and creation of new fractures is presented, and pillar capacities and stiffnesses are compared with empirical models. The agreement between the models is promising and the new model provides useful insights into the influence of pre-existing fractures. Further work is needed to consider the effects of three-dimensional loading and other boundary condition problems.  相似文献   

Stereological Analysis of Fracture Networks along Cylindrical Galleries     

A. K. Gupta  P. M. Adler 《Mathematical Geology》2006,38(3):233-267

The intersections between three-dimensional fracture networks consisting of constant- and variable-size disks with a gallery were systematically analyzed. Exact and approximate analytical formulae were derived for the numbers of partial or full intersections. These predictions were verified by Monte Carlo simulations. Trace length distributions were studied by numerical techniques for various disk distributions. These simulations showed that differences between various disk distributions are very small when trace length distributions with the same average and standard deviations are compared.  相似文献   

Attenuation, transport and diffusion of scalar waves in textured random media     

L. Margerin   《Tectonophysics》2006,416(1-4):229

Most theoretical investigations of seismic wave scattering rely on the assumption that the underlying medium is statistically isotropic. However, deep seismic soundings of the crust as well as geological observations often reveal the existence of elongated or preferentially oriented scattering structures. In this paper, we develop mean field and radiative transfer theories to describe the attenuation and multiple scattering of a scalar wavefield in an anisotropic random medium. The scattering mean free path is found to depend strongly on the propagation direction. We derive a radiative transfer equation for statistically anisotropic random media from the Bethe–Salpeter formalism and propose a Monte Carlo method to solve this equation numerically. At longer times, the energy density is shown to obey a tensorial diffusion equation. The components of the diffusion tensor are obtained in closed form and excellent agreement is found between Monte Carlo simulations and analytical solutions of the diffusion equation. The theory has important potential implications for lithospheric models where scatterers are for example flat structures preferentially aligned along the surface. In this simple geometry, analytical expressions of the Coda Q parameter can be given explicitly in the diffusive regime. Our results suggest that pulse broadening and coda decay are controlled by different parameters, related to the eigenvalues of the diffusion tensor. These eigenvalues can differ by more than one order of magnitude. This theory could be applied to probe the anisotropy of length scales in the lithosphere.  相似文献