低围压条件下无烟煤三轴蠕变特性试验研究
Experimental study on triaxial creep characteristics of the anthracite coal under low confining pressure
闫建兵 1张小强 2宋选民 1王开 2姜玉龙 2岳少飞1
作者信息
- 1. Key Laboratory of In-situ Property Improving Mining of Ministry of Education(Taiyuan University of Technology),Taiyuan 030024,China
- 2. College of Mining Engineering,Taiyuan University of Technology,Taiyuan 030024,China
- 折叠
摘要
旧采遗留煤柱的蠕变特性直接影响井下工程的长期稳定性,小煤柱边界及内部弹性核区的应力环境一般为低围压三向应力状态.为了研究山西沁水煤田3#无烟煤柱的蠕变特性及长期稳定性,进行了4种低围压(0.5、1.0、1.5和2.0 MPa)状态的常规三轴压缩和三轴蠕变试验,探索了不同围压条件下无烟煤的蠕变规律,并基于试验数据建立了能较好地描述各蠕变阶段的非线性黏弹塑性蠕变模型.试验研究结果表明:1)轴向应力大于屈服应力时,无烟煤的蠕变经历三个阶段:即初始蠕变、稳定蠕变和加速蠕变阶段;2)无烟煤试样的瞬时弹性应变与轴向应力水平大致呈线性增长关系,且围压越小,其瞬时弹性应变随轴向应力水平的增长速率越快;3)与瞬时强度相比,无烟煤的长期强度降低20%;蠕变特性降低了无烟煤的强度参数,与短期抗剪强度相比,其内摩擦角和内聚力分别降低了8%和14%.
Abstract
The creep characteristics of coal pillars left over from old mining directly affect the long-term stability of underground engineering.To study the creep characteristics and long-term stability of the No.3 anthracite pillar in Qinshui Coal Field,Shanxi Province,China,conventional triaxial compression and triaxial creep tests were conducted under four low confining pressures(0.5,1.0,1.5 and 2.0 MPa),and the creep laws of the anthracite samples under different confining pressures were explored.Moreover,based on the test data,a nonlinear viscoelastic-plastic creep model was established which could better describe each creep stage.The test results show that:1)when the axial stress is higher than the yield stress,the creep of anthracite undergoes three stages:initial creep,steady creep,and accelerated creep;2)the instantaneous elastic strain of anthracite increases linearly with the axial stress level,and the smaller the confining pressure was,the faster the instantaneous elastic strain increased;3)Compared with the instantaneous strength,the long-term strength of anthracite decreased by approximately 20%.The creep properties reduced the shear strength of anthracite,and compared with the short-term shear strength,the internal friction angle and cohesion decreased by 8%and 14%,respectively.
关键词
无烟煤/低围压/蠕变试验/蠕变模型/长期强度Key words
anthracite/low confining pressure/creep test/creep model/long-term strength引用本文复制引用
基金项目
National Natural Science Foundation of China(51704204)
National Natural Science Foundation of China(51974194)
National Natural Science Foundation of China(52104097)
Basic Research Program of Shanxi Province,China(20210302123147)
Basic Research Program of Shanxi Province,China(20210302124352)
出版年
2023
NETL
NSTL
维普
万方数据