Multi-level fracture network model for coupled seepage and stress fields in rock mass

Abstract

It is one of the issues of subsurface water resource research to investigate the models for coupled seepage and stress fields in rock mass. The present models can be summarized as the three types of (equivalent) continuum model, the fracture network model and the double media model. In this paper, a new multi-level fracture network model is proposed for coupled seepage and stress fields in rock mass. According to the scale and permeability, the ruptures, faults, fractures, joints and pores in rock mass are divided into four levels, i.e. the level-1 real fracture network, the level-2 random fracture network, the level-3 equivalent continuum system and the level-4 continuum system. The level-1 real fracture network is composed of larger ruptures and faults, whose distribution, mechanical and hydro-mechanical parameters can be determined from the real geological information. Based on the fractures measurement and statistics, the level-2 random fracture network is simulated by means of Monte-Carlo technique. The level-3 equivalent continuum system is established to reflect the overall behaviour of small joints by means of the theory of hydraulic conductivity tensor. The level-4 continuum system is composed of pores in rock, whose behaviour can be represented by the homogeneous and isotropic parameters. These fracture networks of four levels are related to each other by water and energy balance. In fracture network of each level, the different interaction between seepage and stress is introduced to construct the multi-level fracture network model for coupled seepage and stress fields in rock mass. An engineering example is also given to show the applicability of the proposed model. © 2004 John Wiley and Sons, Ltd.