不同应力路径下层理煤体力学特性试验研究  

Experimental study on mechanical properties of bedding coal under different stress paths

作　　者：范浩[1] 王磊[1] 王连国[2] FAN Hao;WANG Lei;WANG Lian-guo(State Key Laboratory of Mining Response and Disaster Prevention and Control in Deep Coal Mine,Anhui University of Science and Technology,Huainan,Anhui 232001,China;State Key Laboratory for Geomechanics and Deep Underground Engineering,China University of Mining and Technology,Xuzhou,Jiangsu 221116,China)

机构地区：[1]安徽理工大学深部煤矿采动响应与灾害防控国家重点实验室,安徽淮南232001 [2]中国矿业大学深部岩土力学与地下工程国家重点实验室,江苏徐州221116

出　　处：《岩土力学》2024年第2期385-395,共11页Rock and Soil Mechanics

基　　金：安徽省高校自然科学研究重点项目(No.KJ2021A0457);安徽省科技重大专项(No.202203a07020010);安徽理工大学引进人才科研启动基金(No.2021yjrc15)。

摘　　要：为探究不同应力路径下层理煤体力学特性和破坏特征,利用MTS816岩石力学试验系统对0°、30°、45°、60°和90°层理倾角煤样开展了常规三轴加载、增轴压卸围压和恒轴压卸围压应力路径下的力学试验,分析了应力路径和层理倾角对煤样强度、变形及破坏特征的影响规律。研究结果表明:(1)常规三轴加载条件下煤样在达到峰值强度前,应力-应变曲线呈近线性关系,达到峰值强度后,应力-应变曲线迅速跌落;增轴压卸围压条件下,随着卸荷比的增加,轴向应变增量比呈线性增加趋势,而环向应变增量比和体积应变增量比呈低速增长-急剧增长-平稳增长的三阶段变化特征;恒轴压卸围压条件下,轴向应变增量比、环向应变增量比和体积应变增量比均呈低速增长-急剧增长的两阶段变化特征。(2)随着层理倾角的增加,不同应力路径下煤样峰值强度和轴向峰值应变均呈先减小后增大的V型变化趋势,在0°时达到最大值,在60°时达到最小值。(3)随着卸荷比的增大,煤样变形模量先平缓后迅速劣化,泊松比先缓慢增加后呈指数形式增加,临界卸荷比随层理倾角的增大先增加后减小;当层理倾角相同时,增轴压卸围压条件下的临界卸荷比低于恒轴压卸围压。(4)常规三轴加载条件下煤样发生脆性剪切破坏,增轴压卸围压和恒轴压卸围压条件下煤样呈张拉-剪切混合破坏模式,当层理倾角为60°时,煤样主剪切破裂面角度与层理倾角几乎一致。To investigate the mechanical properties and failure characteristics of bedding coal under different stress paths,mechanical tests were conducted using the MTS816 rock mechanics testing system.Coal samples with bedding angles of 0°,30°,45°,60°,and 90° were subjected to tests under three stress paths:conventional triaxial loading,increasing axial pressure unloading confining pressure,and constant axial pressure unloading confining pressure.The study analyzed the influence of stress paths and bedding angles on the strength,deformation,and failure characteristics of the coal samples.The results indicate the following:Under the path of conventional triaxial loading,the stress-strain curves of the coal samples show a nearly linear relationship before reaching the peak point,followed by a rapid drop in stress after reaching the peak.Under the path of increasing axial pressure unloading confining pressure,the axial strain increment ratio exhibits a linear increasing trend as the unloading ratio increases.The circumferential strain increment ratio and volumetric strain increment ratio display a three-stage change characteristic,involving low-speed growth,rapid growth,and stable growth.Under the path of constant axial pressure unloading confining pressure,the axial strain increment ratio,circumferential strain increment ratio,and volumetric strain increment ratio exhibit a two-stage change characteristic,involving low-speed growth and rapid growth.The peak strength and axial peak strain of the coal samples exhibit a V-shaped trend with increasing bedding angle under different stress paths.They initially decrease and then increase,reaching the maximum value at 0°and the minimum value at 60°.As the unloading ratio increases,the deformation modulus of the coal sample initially stabilizes and then rapidly deteriorates.The Poisson's ratio first slowly increases and then exponentially increases.The critical unloading ratio initially increases and then decreases with increasing bedding angle.When the bedding angle is the

关 键 词：应力路径 层理煤体 力学特性 破坏特征 卸荷比 

分 类 号：TD821[矿业工程—煤矿开采]