循环荷载下深部卸荷煤体力学特性及能量演化规律研究  

Study on mechanical properties and energy evolution of deep unloading coal under cyclic loading

作　　者：王磊[1] 邹鹏 范浩[1] 谢广祥[1] 晋康 钟浩 WANG Lei;ZOU Peng;FAN Hao;XIE Guangxiang;JIN Kang;ZHONG Hao(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)

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

出　　处：《岩石力学与工程学报》2024年第10期2341-2355,共15页Chinese Journal of Rock Mechanics and Engineering

基　　金：安徽高校协同创新资助项目(GXXT-2020-055);安徽省科技重大专项(202203a07020010)。

摘　　要：为探究循环荷载作用下卸荷煤体力学特性及能量演化规律,利用MTS816岩石力学试验系统对煤样开展变下限和恒下限三轴循环荷载试验,通过获取全过程应力–应变曲线分析煤样的力学参数变化关系,基于能量原理研究受载煤样循环过程的能量演化规律。结果表明:(1)相较于CG组,循环荷载作用下煤样的峰值应力增量极值为3.540 MPa,整体变化不大。XH1和XH2组的轴向应变和侧向应变与围压大小分别成正相关和负相关,体积应变分别为先增加后稳定再增加和先增加后减少再增加的变化趋势。(2)循环荷载作用下煤样的加载模量与循环次数成正相关,与应力水平成负相关;应变硬化模量和跌落模量均与围压成负相关。高围压条件弱化了抵抗非弹性模型的能力,且这种弱化趋势与应力路径无关;循环应力路径对煤样变形特征影响显著。(3)恒下限路径或高围压作用下煤样的能量密度更高。各循环水平内煤样的耗散能密度与输入能密度规律基本一致,呈先降低后稳定的变化趋势,弹性能密度总体稳定。(4)循环荷载作用下煤样的弹性能密度占总输入能密度比例超过89.11%,二者的均值呈线性关系,总能量主要以弹性能的形式存储,且这种存储能力与围压无关。耗散能密度与弹性能密度均值呈幂函数型变化,且循环应力水平升高耗散能的能量竞争能力逐渐增强。In order to explore the mechanical properties and energy evolution law of unloading coal under cyclic loading,the MTS816 rock mechanics test system was used to carry out triaxial cyclic loading tests with variable lower limit and constant lower limit of coal samples.The relationship between mechanical parameters of coal samples was analyzed by obtaining the whole process stress-strain curve,and the energy evolution law of coal samples during cycle loading process was studied based on the energy principle.The results show that:(1) Compared with the CG group,the peak stress increment extreme value of the coal samples under cyclic loading is 3.540 MPa,and the overall change is not large.The axial strain and lateral strain of the XH1 and XH2 groups are positively correlated and negatively correlated with the confining pressure,respectively.The volumetric strain of the XH1group increases first and then stabilized and then increased,while that of the XH2 group increased first and then decreased and then increased.(2) The loading modulus of coal samples under cyclic loading is positively correlated with the number of cycles and negatively correlated with the stress level.Both the strain hardening modulus and the drop modulus are negatively correlated with the confining pressure.The high confining pressure condition weakens the ability to resist the inelastic model,and this weakening trend is independent of the stress path.The cyclic stress path has a significant effect on the deformation characteristics of coal samples.(3) The energy density of coal samples is higher under the action of constant lower limit path or high confining pressure.The dissipation energy density of coal samples in each cycle level is basically consistent with the input energy density,showing a trend of decreasing first and then stabilizing,and the elastic energy density is generally stable.(4) Under cyclic loading,the elastic energy density of coal samples accounts for more than 89.11% of the total input energy density,and the mean value of the t

关 键 词：岩石力学 煤 循环荷载 力学特性 能量演化 

分 类 号：TU45[建筑科学—岩土工程]