一种渗流吸水诱发岩体强度弱化的有限体积数值计算方法  

A FINITE VOLUME NUMERICAL SIMULATION METHOD FOR ROCK MASS STRENGTH WEAKENING BY SEEPAGE WATER ABSORBING

作　　者：郭影 姜忻良[1] 曹东波[3] 白铁钧[2] 朱广轶 冯春[4] GUO Ying;JIANG Xin-liang;CAO Dong-bo;BAI Tie-jun;ZHU Guang-yi;FENG Chun(School of Civil Engineering,Tianjin University,Tianjin 300072,China;School of Civil Engineering,Shenyang University,Shenyang 110044,China;Public English Department,Shenyang Institute of Engineering,Shenyang 110136,China;Institute of Mechanics,Chinese Academy of Sciences,Beijing 100190,China)

机构地区：[1]天津大学建筑工程学院,天津300072 [2]沈阳大学建筑工程学院,沈阳110044 [3]沈阳工程学院公外部,沈阳110136 [4]中国科学院力学研究所,北京100190

出　　处：《工程力学》2018年第7期139-149,共11页Engineering Mechanics

基　　金：国家青年科学基金项目(51208356);辽宁省自然科学基金指导计划项目(20170540649;20170540651);国家留学基金项目(201708210323)

摘　　要：传统的渗流数值计算方法难以较真实地描述岩石材料性能劣化和渗透性演化机制。该文提出了一种渗流吸水诱发岩体强度弱化的有限体积数值计算方法。利用高斯散度定理采用有限体积法求解水在岩体中的渗流过程及岩体的变形破坏过程,建立了基质吸水引起岩体模量及强度弱化的理论模型及相应的数学表述。基于考虑吸水弱化算法的各向同性孔隙渗流模型,模拟了低、高两种边界流体压力下某粉砂岩试样的吸水软化过程和不同吸水时间下试样的单轴压缩过程。数值算例表明:边界流体压力越高,试样达到整体饱和状态的时间越快;渗流初期以自由水渗流填充孔隙为主,渗流后期以孔隙内自由水向基质吸水的转化为主;边界流体压力对渗流速率具有明显控制作用,但对基质吸水速度无影响;随着吸水时间的增加,试样的强度(黏聚力、内摩擦角)逐渐减小至残余值,得到的基质吸水含量随时间变化的数值解与理论解基本一致,表明了数值算法的计算精度,可以用于隧道突水、围岩稳定性等实际岩体工程问题的渗流-应力耦合效应分析。It is difficult to describe the deterioration mechanism and permeability evolution mechanism of rock materials by the traditional numerical method of seepage flow.A finite volume numerical method is proposed for the weakening strength of rock mass induced by seepage water absorption.The seepage process of water and the deformation and destruction process of rock mass are solved with the finite volume method by using the Gauss divergence theorem,and a theoretical model for modulus and strength of the weakening rock mass induced by the matrix suction is established and the corresponding mathematical expressions are given.Based on the isotropic pore seepage model considering a water weakening algorithm,the softening process of a powder sandstone sample and the uniaxial compression process of specimens with different water absorption time are simulated under both low and high boundary fluid pressures.The numerical examples show that the higher the pressure of boundary fluid,the faster the sample reaches the overall saturation state.In the early stage of seepage,the free water flow fills the pores,while it is dominated by the transformation from the free water in the pore to the matrix suction in the later stage.The boundary fluid pressure has obvious control effect on the flow rate,but has no effect on the water absorption speed of the matrix suction.With the increase of the absorption time,the strength(cohesion and internal friction angle)of the sample is gradually reduced to the residual value,and the matrix water absorption content obtained by using this method is basically consistent with the theoretical solution.This demonstrates the calculation precision of the numerical algorithm and that it can be used to analyze the seepage and stress coupling effect on actual rock mass engineering problems such as tunnel water breakthrough and surrounding rock stability.

关 键 词：数值分析 岩体 渗流特性 强度弱化 有限体积法 

分 类 号：TU452[建筑科学—岩土工程]