不同加载速率无烟煤蠕变特性及能量演化规律  

Creep properties and energy evolution of anthracite coal with different loading rates

作　　者：岳少飞 王开[1,2] 张小强[1,2] 康天合[1,2] 闫建兵 姜玉龙[1,2] 郭泽雄[1,2] YUE Shaofei;WANG Kai;ZHANG Xiaoqiang;KANG Tianhe;YAN Jianbing;JIANG Yulong;GUO Zexiong(College of Mining Engineering,Taiyuan University of Technology,Taiyuan 030024,China;Key Laboratory of In-Situ Property-Improving Mining of Ministry of Education,Taiyuan University of Technology,Taiyuan 030024,China)

机构地区：[1]太原理工大学矿业工程学院,山西太原030024 [2]太原理工大学原位改性采矿教育部重点实验室,山西太原030024

出　　处：《煤炭学报》2023年第8期3060-3075,共16页Journal of China Coal Society

基　　金：国家自然科学基金资助项目(51974194,51704204);中国矿业大学煤炭资源与安全开采国家重点实验室开放研究基金资助项目(SKLCRSM22KF003)。

摘　　要：动压影响下蠕变煤体的力学特性对复采区遗留煤柱的稳定性及其控制具有重要的工程意义。通过开展不同加载速率条件下无烟煤的分级加载蠕变和加卸载试验,对无烟煤蠕变过程的应变特征、弹性模量及蠕变速率演化特征进行研究,并基于无烟煤的线型储能规律表征了蠕变过程的能量耗散规律,进一步阐释了无烟煤蠕变“硬化-损伤”机制。结果表明:加载速率小于0.04 mm/s时,无烟煤试件的轴向应变表现出明显的瞬时特性,但径向应变表现出明显的滞后性和蠕变性;随着加载速率的增加,试样在加载阶段的轴向硬化及径向扩容现象显著增强,蠕变速率衰减特征越显著。试样的实际屈服应力与加载速率满足线性下降关系,其储能系数、蠕变极限弹性能随加载速率增加均呈现先增加后趋于稳定的趋势;各应力水平的能量耗散率演化呈现“降低—稳定—增加”的趋势,分别对应试件的压密、弹性和屈服破坏阶段。从能量耗散角度分析无烟煤试样的“硬化-损伤”机制:硬化及损伤效应作用于蠕变全过程,试样在弹性阶段硬化及损伤作用效果相当导致试样的能量耗散率稳定,试样进入屈服破坏阶段后损伤效应占主导地位导致能量耗散率快速增加;试样硬化及损伤效应均随加载速率的增大逐渐显著,加载速率小于0.04 mm/s时,试样硬化效应强于损伤效应导致试样极限弹性能快速增加;加载速率增大导致的屈服应力降低会加速试样的损伤演化,当加载速率大于0.04 mm/s后,试样的损伤效应显著增强,硬化及损伤相互制约导致试样极限弹性能趋于稳定。The mechanical properties of creep coal bodies under the influence of dynamic pressure have important engin-eering significance for the stability and control of remained coal pillars in the re-mining area.The strain characteristics,elastic modulus and creep rate evolution characteristics of creep process of anthracite coal were studied by carrying out the graded loading creep and loading-unloading tests under different loading rates.The energy dissipation law of creep pro-cess was characterized based on the linear energy storage law of anthracite coal,and the“hardening-damage”mechanism of creep of anthracite coal was further explained.The results show that when the loading rate is less than 0.04 mm/s,the axial strain of the anthracite specimen shows obvious transient characteristics,but the radial strain shows obvious hyster-esis and creep.With the increase of the loading rate,the axial hardening and radial expansion of the specimen in the load-ing stage are significantly enhanced,and the creep rate decay characteristics appear more obvious.The actual yield stress of the specimen meet the linear decreasing relationship with the loading rate,and its energy storage coefficient and creep limit elastic energy show the trend of increasing and then stabilizing with the increase of loading rate.The evolution of en-ergy dissipation rate of each stress level shows the trend of“decreasing-stabilizing-increasing”,which is corresponded to the compression-density,elasticity and yielding damage stages of the specimen,respectively.The hardening-damage mechanism of anthracite specimens was analyzed from the perspective of energy dissipation.The hardening and damage effects act on the whole creep process,and the hardening and damage effects are comparable in the elastic stage,resulting in a stable energy dissipation rate of the specimen,and the damage effect dominates after the specimen enters the yield damage stage,resulting in a rapid increase in the energy dissipation rate.The specimen hardening and damage effects grad

关 键 词：分级加载蠕变 加载速率 蠕变特性 硬化-损伤 能量耗散 

分 类 号：TD315[矿业工程—矿井建设]