岩石抗压强度的尺寸效应及端部约束的离散元数值模拟  

SIZE EFFECT OF COMPRESSION STRENGTH AND END CONSTRAINT OF ROCKS BY DISTINCT ELEMENT SIMULATION

作　　者：孙超[1,2] 刘芳[1,2,3] 蒋明镜[1,2,3] 陈贺[1,2] 

机构地区：[1]同济大学地下建筑与工程系,上海200092 [2]同济大学岩土及地下工程教育部重点实验室,上海200092 [3]同济大学土木工程防灾国家重点实验室,上海200092

出　　处：《岩石力学与工程学报》2014年第A02期3421-3428,共8页Chinese Journal of Rock Mechanics and Engineering

基　　金：国家重点基础研究发展计划(973)项目(2011CB013504;2014CB046901);国家杰出青年科学基金项目(51025932)

摘　　要：为研究岩石抗压强度尺寸效应与端部约束的关系,将基于室内理想胶结颗粒接触试验所得到的岩石胶结接触模型植入二维离散元程序,模拟不同端部约束条件下不同高宽比试样的单轴压缩试验,并将数值试验结果与基于室内实测数据得到的理论公式计算结果进行对比。模拟结果证实端部约束是无微裂隙试样单轴压缩强度尺寸效应的原因之一,无端部摩擦时尺寸效应消失。相同端部约束条件下,高宽比较大的试样发生破坏所需胶结破坏数目减小,因此试样强度随高宽比增加而减小,但当高宽比大于2.0时强度基本不变。高宽比较小时,试样强度随端部摩擦因数增加而增大,当摩擦因数大于0.5时,试样强度基本保持稳定,摩擦因数越大,试样破坏所需的胶结破坏数目越大,胶结压剪扭破坏所占比例越大。In order to understand the size effect of compression strength of rocks caused by the end constraint conditions,a bond contact model of rocks based on micromechanical test data was implemented into the two-dimensional distinct element code for simulating the uniaxial compression tests of rock samples with different slenderness ratios under different constraint conditions. The simulation results were compared with theoretical solutions. The simulation results confirm that end constraint is one of the reasons causing the size effect of uniaxial compression strength of a homogenous rock sample,and the size effect disappears when the ends of the samples are frictionless. Under the same constraint conditions,the samples with a larger slenderness ratio break at a smaller number of bond breakage,so the uniaxial compression strength decreases with the increase of the slenderness ratio until it reaches a steady value when the ratio exceeds 2.0. The strength of rock samples with a small slenderness ratio increases with the increase of the friction coefficient of the ends of samples until it reaches a steady value when the coefficient exceeds 0.5. In addition,the number of bond breakages at failure and the proportion of bond compression-shear-torsion failure substantially increase with the increase of friction coefficient.

关 键 词：岩石力学 岩石强度 离散元法 尺寸效应 单轴压缩试验 

分 类 号：TU45[建筑科学—岩土工程]