单轴压缩试验端面摩擦效应及损伤演化规律研究  

Study on friction effect and damage evolution of end face in uniaxial compression test

作　　者：李单林 刘广建 贾瑞锋 薛飞 王康宇 LI Shanlin;LIU Guangjian;JIA Ruifeng;XUE Fei;WANG Kangyu(Key Laboratory of Rock Mechanics and Geohazards of Zhejiang Province,School of Civil Engineering,Shaoxing University,Shaoxing 312000,China)

机构地区：[1]绍兴文理学院土木工程学院浙江省岩石力学与地质灾害重点实验室,浙江绍兴312000

出　　处：《采矿与岩层控制工程学报》2021年第3期95-104,共10页Journal of Mining and Strata Control Engineering

基　　金：浙江省自然科学基金资助项目(LQ20E040002);绍兴文理学院2018年科研资助项目(2018LG1004)。

摘　　要：单轴压缩试验的端面摩擦效应对试样的变形破坏特征有较大影响。运用块体离散元软件UDEC,基于库仑滑移准则,开展了不同端面摩擦因数下的单轴压缩数值试验,研究了不同岩性和不同高宽比试样的损伤演化规律,从应力应变关系、裂缝扩展及应力分布等角度探究了端面摩擦效应的机理。结果表明:①端面摩擦效应会抑制微观裂缝的萌生与扩展,使脆性试样的破坏形式由劈裂向剪切或拉-剪共同破坏转变,使砂岩的强度明显增大,对煤和泥岩的强度影响较小;②端面摩擦对试样强度与破坏特征的影响存在阈值,50 mm×100 mm的标准煤、泥岩、砂岩试样的端面摩擦因数阈值分别为0.2,0.2,0.5;③端面摩擦引起的“裂缝三角形抑制区”与应力局部集中带是不同高度试样强度存在尺寸效应的主要原因。建议在进行室内单轴压缩试验时,采取减摩措施来规避端面摩擦效应。The end friction effect in uniaxial compression test has a great influence on the deformation and failure characteristics of the specimen.Based on the Coulomb slip criterion,numerical tests of uniaxial compression under different end friction coefficients are carried out by using UDEC software.The deformation and failure of the specimens with different lithology and different aspect ratios are studied.The mechanism of the end friction effect is explored from the angle of the stress-strain relationship,crack propagation and stress distribution.The results show that:①The end friction effect can inhibit the initiation and propagation of micro cracks,and change the failure mode of brittle samples from splitting to shear or tension shear joint failure,which makes the strength of sandstone increase significantly,and has little effect on the strength of coal and mudstone;②There is a threshold value for the effect of end friction on the strength and failure characteristics of the samples.The threshold values of the end friction coefficient of the 50 mm×100 mm standard coal,mudstone and sandstone samples are 0.2,0.2 and 0.5,respectively;③The results show that the size effect of specimen strength at different heights is mainly caused by"crack triangle inhibition zone"and local stress concentration zone caused by end friction.It is suggested that the friction reduction measures should be taken to avoid the end friction effect in the indoor uniaxial compression test.

关 键 词：端面摩擦 UDEC 岩性 尺寸效应 裂缝扩展 

分 类 号：TD45[矿业工程—矿山机电]