裂隙煤岩体的流固耦合精细模型

Fluid-solid coupling detailed model of rock-coal mass

将裂隙煤岩体视为裂隙-孔隙双重介质,以满足某种概率分布的主干裂隙网络描述煤岩体裂隙的分布;将主干裂隙间包含低序次裂隙的基质煤(岩)块视为各向同性孔隙介质,建立裂隙煤岩体的流固耦合精细模型。对不同介质分别进行渗流-应力耦合分析,在应力计算时采用等厚度节理单元进行模拟,在渗流计算时,采用节理单元的中面坐标将节理单元转换为线单元进行模拟的数值技术,解决2类介质耦合求解时存在不同介质间流体的交换问题。研究结果表明:裂隙煤岩体流固耦合的数值实验结果反映了裂隙煤岩体渗流的各向异性,孔隙渗流滞后裂隙渗流现象,体现了煤岩体贯通主干裂隙网络对渗流场分布起控制作用;数值实验结果较真实地模拟了煤岩体应力分布的复杂性,体现了孔隙单元的有效体积应力和裂隙单元的有效法向应力随渗流发展的时效演化规律。

The fracture rock was regarded as fluid-solid dual media, and the distribution of fractured rock was described by main discrete fracture network, which obeys certain kinds of probability distribution. Matrix rock surfaces with low order fracture in main fracture were treated as isotropic pore medium to establish the fluid-solid coupling model of fine rock mass medium. The analysis of seepage-stress coupling in different mediums was conducted, uniform thickness unit was adopted to simulate when calculating the stress of fracture medium. While calculating seepage, mid-plane coordinate of joint element was adopted to convert joint element into line element to simulate the problem that gas exchange between different medium exists when solving two kinds of medium coupling. The results show that both the anisotropy of seepage in fractured rock and the phenomenon of porosity permeating flow delaying fracture seepage are reflected by simulation experiment for fluid-solid coupling model of fine rock mass medium, the complexity of stress distribution in rock mass is revealed by simulation experiment. The aging evolutional law of both effective cubage stresses of pore unit and effective normal stress of fracture unit that increase with the development of seepage are revealed.