Effects of water intrusion and loading rate on mechanical properties of and crack propagation in coal-rock combinations
Effects of water intrusion and loading rate on mechanical properties of and crack propagation in coal-rock combinations
复制标题
水侵入和加载速率对煤岩组合体力学性能和裂纹扩展的影响
DOI：
10.1007/s11771-017-3444-6
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发表时间：
2017-02-01
影响因子：
4.4
通讯作者：
Li Jing
中科院分区：
文献类型：
--
作者：
Chen Tian;Yao Qiang-ling;Li Jing
解决干旱地区煤矿地下水赋存问题，需要了解水侵入和加载速率对煤岩组合体力学性质和裂隙发育的影响。准备了54个煤岩组合，并将其平均分成含有不同含水量的组在加载速率为0.1 ~ 0.6mm/min的单轴压缩条件下进行声发射试验，结果表明：在不同的加载速率下，峰后模量随含水率和加载速率的增加而降低。相反，峰值应变随含水率的增加而增加，并随加载速率的增加而波动。更重要的是，刚度和应力之间的关系，结合声发射的累积计数，可以用来精确地预测裂纹扩展的所有阶段。这对研究含水率和加载速率对裂纹扩展的影响以及准确计算力学性能具有重要意义。裂纹闭合、裂纹萌生和裂纹损伤的应力阈值不随含水率和加载速率的变化而变化，分别占峰值应力的15.22%、32.20%和80.98%。这些成果有助于开发矿井蓄水方法、确定防水煤岩柱的必要宽度和富水巷道的支护方法，同时也促进了对煤岩组合力学特性和裂纹扩展规律的认识。
Tackling the problems of underground water storage in collieries in arid regions requires knowledge of the effect of water intrusion and loading rate on the mechanical properties of and crack development in coal-rock combinations. Fifty-four coal-rock combinations were prepared and split equally into groups containing different moisture contents (dry, natural moisture and saturated) to conduct acoustic emission testing under uniaxial compression with loading rates ranging from 0.1 mm/min to 0.6 mm/min. The results show that the peak stress and strength-softening modulus, elastic modulus, strain-softening modulus, and post-peak modulus partly decrease with increasing moisture content and loading rate. In contrast, peak strain increases with increasing moisture content and fluctuates with rising loading rate. More significantly, the relationship between stiffness and stress, combined with accumulated counts of acoustic emission, can be used to precisely predict all phases of crack propagation. This is helpful in studying the impact of moisture content and loading rate on crack propagation and accurately calculating mechanical properties. We also determined that the stress thresholds of crack closure, crack initiation, and crack damage do not vary with changes of moisture content and loading rate, constituting 15.22%, 32.20%, and 80.98% of peak stress, respectively. These outcomes assist in developing approaches to water storage in coal mines, determining the necessary width of waterproof coal-rock pillars, and methods of supporting water-enriched roadways, while also advances understanding the mechanical properties of coal-rock combinations and laws of crack propagation.