孔隙率对岩体中THM耦合作用的弹塑性有限元分析  

Elasto-plastic FEM Analyses for Influences of Porosity on T-H-M Coupling in Rock Mass

作　　者：张玉军[1] 琚晓冬[2] 

机构地区：[1]中国科学院武汉岩土力学研究所岩土力学与工程国家重点实验室,武汉430071 [2]河南理工大学土木工程学院,河南焦作454000

出　　处：《地下空间与工程学报》2016年第2期426-435,共10页Chinese Journal of Underground Space and Engineering

基　　金：国家重点基础研究发展计划(973)资助项目(2010CB732101);国家自然科学基金(51379201)

摘　　要：笔者使用Taron等提出的颗粒聚集体的压力溶解模型和摩尔-库伦准则,假设在饱和的石英颗粒聚集岩体中有一实验室尺度的高放废物地质处置库模型,针对其拟定两种计算工况:(1)内摩擦角和黏聚力均为常数;(2)内摩擦角为常数,黏聚力是孔隙率的负指数函数,进行4a处置时段的热-水-应力(THM)耦合有限元数值模拟,就岩体中的温度场、渗流场、应力场和浓度场的变化及分布情况进行了考察。结果显示:与黏聚力是常数的情况相比,黏聚力随孔隙率而变化时,岩体相同部位进入屈服阶段的时机滞后,塑性区减小,并推迟了塑性部位的溶质浓度、迁移/沉淀质量、反应体积和颗粒贯穿深度的突变时间;弹塑性分析中由于应力调整和增大了分子扩散系数,使得塑性区的颗粒介质的溶解、迁移和沉淀相比于弹性区有明显的变化,并对渗流场(孔隙水的压力及流速)和应力场产生显著的影响。The model of pressure solution for granular aggregates established by Taron was introduced into the FEM code for analysis of T-H-M coupling in porous media and the Mohr-Coulomb yield criterion was used. Aiming at a model of hypothetical nuclear waste repository in a saturated quartz aggregate rock mass with a laboratory scale,two computation cases were designed：（ 1） both of the internal friction angle and cohesion are constants;（ 2） the internal friction angle is constant,but the cohesion is a negative exponent function of porosity,then the corresponding numerical simulations for a disposal period of 4 years were carried out,and the states of temperatures,solute concentrations in the intergranular fluid film and at the pore space,removal and precipitation masses,porosities and permeabilities,pore pressures,flow velocities and stresses in the rock mass were investigated. The results show： compared with the case of constant cohesion,when the cohesion changes with the porosity,the time at which the same parts of rock mass entering yield state delays,the plastic zone decreases,and the times of causing sudden change of solute concentrations,removal / precipitated masses, cumulative granular interpenetrations and reaction volumes are postponed.Because of the stress adjustment and the increasing molecular diffusivity in the elasto-plastic analysis,there are obvious changes of solution,transfer and precipitation of aggregate medium in the plastic zones,and the seepage field（ including pressures and flow velocities of pore water） and the stress field are markedly influenced by these changes.

关 键 词：压力溶解 孔隙率 弹塑性模型 热-水-应力耦合 有限元分析 

分 类 号：TU452[建筑科学—岩土工程]