考虑初始孔隙性的含瓦斯煤岩力学本构关系与损伤演化研究  

Study on Mechanical Constitutive Relationship and Damage Evolution of Gas-bearing Coal Based on Initial Pore-cracks

作　　者：丁鑫[1] 肖晓春[1] 吴迪[1] 吕祥锋 潘一山[1,3] 白润欣 DING Xin;XIAO Xiaochun;WU Di;Lyu Xiangfeng;PAN Yishan;BAI Runxin(School of Mechanics and Engineering,Liaoning Technical University,Fuxin 123000,China;School of Civil and Resource Engineering,University of Science&Technology Beijing,Beijing 100083,China;School of Environment,Liaoning University,Shenyang 110136,China;School of Science&School of Pre-university,Dalian Minzu University,Dalian 116600,China)

机构地区：[1]辽宁工程技术大学力学与工程学院,阜新123000 [2]北京科技大学土木与资源工程学院,北京100083 [3]辽宁大学环境学院,沈阳110136 [4]大连民族大学理学院,预科教育学院,大连116600

出　　处：《材料导报》2021年第18期18096-18103,共8页Materials Reports

基　　金：国家自然科学基金项目(51774164,51974186,51974147);辽宁省教育厅青年育苗项目(LJ2020QNL001);辽宁工程技术大学创新团队项目(LNTU20TD-17)。

摘　　要：冲击地压及瓦斯次生灾害更易在深部复杂的地质构造区域发生,其实质是煤岩介质在变化多样的地应力、采动应力与瓦斯共同作用下的力学平衡系统失稳过程,准确描述含瓦斯煤岩受载过程的力学关系是明确煤岩动力灾害孕育与发生机制的根本。考虑原生裂隙对煤岩力学性质的劣化特性,将其定义为初始损伤,理论推导了以孔隙率表征的初始损伤公式,综合考虑初始孔隙率、吸附瓦斯煤岩基质膨胀、瓦斯运移的软化特性及真三向应力状态,构建了基于非均匀性统计理论的含瓦斯煤岩损伤演化方程及力学本构模型,并定性分析了各参量对煤岩力学性质的影响规律。结果表明:当煤岩初始孔隙率越高时,任意截面的裂纹长度、宽度和条数均增加,有效面积减小,局部更易产生应力集中,损伤曲线在峰值损伤量更高及峰后段增长率略降低,反之,当均质度越高时,其峰值点处的损伤值越低,损伤演化越滞后并集中于峰后阶段发展,相应的损伤演化曲线斜率越大;随瓦斯压力升高,煤岩吸附产生的膨胀应力明显增加,吸附参量a、b值同样对膨胀应力具有促进作用;弹性模量和均质度对煤岩强度及峰后应力降模量均呈现为正相关影响,使煤岩冲击危险性增强;初始损伤和较高的瓦斯压力均促进了煤岩中裂隙的发育,降低了煤岩性质的均一性,使强度和峰后应力降模量减小而塑性特征越发显著并促进煤岩软化,这也是高瓦斯煤层冲击地压低于常规指标发生的原因。Rockbursts and secondary gas disasters are more likely to occur in complex geological structures,under the combined action of varied in-situ stress,mining stress and gas,which is the instability process of the mechanical balance system of coal media.Thus,it is the foundation of coal dynamic disaster incubation and occurrence mechanism,that describing the mechanical relationship of gas-bearing coal loading process accurately.In this paper,the primary crack is considered,defined as the initial damage and its theoretical derivation formula characterized by porosity is obtained,for the deterioration on the mechanical properties of coal.The damage evolution equation and mechanical constitutive model of gas-bearing coal based on non-uniform statistical theory is constructed,which the parameter of initial porosity,expansion of coal matrix gas adsorbed,softening characteristics of gas seepage and true triaxial stress state is considered,and the influence on mechanical properties is analyzed qualitatively.The result show that,the higher initial porosity of coal,the grater of length,width and number of cracks in any section,it's easier to form stress concentration with the effective area reduced,thus,the damage curve had a higher value at peak and a slight decrease in the growth rate of the post peak.Otherwise,the higher the degree of homogeneity,the lower the damage value at the peak,the more lagging the damage evolution is,and the greater the slope of the damage evolution curve.The expansion stress generated by coal adsorption improved signifi-cantly,with the increase of gas pressure,and the adsorption parameters a,b also promote it.The elastic modulus and homogeneity have a positive correlation on the strength of coal,and the modulus of stress reduction at post-peak,which increases the risk of coal burst liability.Both initial damage and gas promote the development of cracks in coal and reduced the uniformity of its properties,and then,the strength and stress drop modulus at post-peak decrease,while the plastic characte

关 键 词：冲击地压 初始损伤 含瓦斯煤岩 力学本构关系 损伤演化 

分 类 号：TD315[矿业工程—矿井建设]