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王 磊,钟 浩,范 浩,等. 循环荷载下含瓦斯煤力学特性及应变场演化规律研究[J]. 煤炭科学技术,2024,52(6):90−101. doi: 10.12438/cst.2024-0328
引用本文: 王 磊,钟 浩,范 浩,等. 循环荷载下含瓦斯煤力学特性及应变场演化规律研究[J]. 煤炭科学技术,2024,52(6):90−101. doi: 10.12438/cst.2024-0328
WANG Lei,ZHONG Hao,FAN Hao,et al. Study on the mechanical properties and strain field evolution of gas-bearing coal under cyclic loading[J]. Coal Science and Technology,2024,52(6):90−101. doi: 10.12438/cst.2024-0328
Citation: WANG Lei,ZHONG Hao,FAN Hao,et al. Study on the mechanical properties and strain field evolution of gas-bearing coal under cyclic loading[J]. Coal Science and Technology,2024,52(6):90−101. doi: 10.12438/cst.2024-0328

循环荷载下含瓦斯煤力学特性及应变场演化规律研究

Study on the mechanical properties and strain field evolution of gas-bearing coal under cyclic loading

  • 摘要: 为研究循环荷载下含瓦斯煤力学特性及应变场演化规律,利用MTS816岩石力学试验系统和自主研制的含瓦斯煤气固耦合装置开展循环加卸载条件下含瓦斯煤力学特性试验,分析循环加卸载下煤样强度和变形特性,并结合数字图像相关(DIC)技术探究含瓦斯煤应变场演化规律。结果表明:①循环加卸载作用下,加卸载曲线之间不重合,形成滞回环,且随着循环次数的增加,滞回环面积逐渐增大,并向着应变增大的方向逐渐移动;不同瓦斯压力的煤样在循环荷载作用下均呈明显的脆性破坏。②循环加卸载作用下,随瓦斯压力升高,煤样峰值强度降低,加载变形模量和卸载变形模量均增大,且卸载变形模量始终大于加载变形模量;随着循环次数的增加,变形模量差值逐渐减小并最终在0~0.1 GPa。③循环加卸载条件下煤样不可逆应变与循环次数之间呈“初始、稳定、加速扩展”的3阶段变化特征,曲线整体从L型向U型趋势发展,累计不可逆应变与循环次数之间呈快速增加、缓慢增加、快速增加的趋势,不可逆应变与累积不可逆应变均随瓦斯压力增大而增加。④在低瓦斯压力下,煤样应变集中区主要为单一竖向应变集中带,随瓦斯压力增大,局部应变集中带逐渐由竖向单一向无序复杂转变;瓦斯压力越大,应变场波动程度越剧烈且剧烈程度主要集中在中部区域;高瓦斯压力下,随瓦斯压力升高,峰值点的个数越多,应变越大。

     

    Abstract: In order to study the mechanical properties and strain field evolution of gas-bearing coal under cyclic loading, the mechanical properties of gas-bearing coal under cyclic loading and unloading conditions were tested with the Rock Mechanics Test (MTS816) system and the independently developed gas-bearing coal gas-solid coupling device. The strength and deformation characteristics of coal samples under cyclic loading and unloading were analyzed, and the strain field evolution of gas-bearing coal was investigated with digital image correlation (DIC) technology. The results indicated that: ① Under the action of cyclic loading and unloading, the loading and unloading curves did not coincide with each other, forming a hysteresis loops. With the increase in the number of cycles, the area of the hysteresis loops gradually increased, and gradually moved towards the direction of increasing strain. Coal samples with varying gas pressures exhibited significant brittle failure under cyclic loading. ② Under the action of cyclic loading and unloading, the peak strength of coal samples decreased, and the loading and unloading deformation modulus increased with the increasing gas pressure. The unloading deformation modulus was always greater than the loading deformation modulus. As the number of cycles increased, the difference in deformation modulus gradually decreased and eventually fell within the range of 0 to 0.1 GPa. ③ Under cyclic loading and unloading conditions, the trend between the irreversible strain of coal samples and the number of cycles was a three-stage pattern of “initial, stable and accelerated expansion”, and the overall curve progressed from an L-shape to a U-shape. The trend between the cumulative irreversible strain and the number of cycles was rapidly increasing, slowly increasing and rapidly increasing, and both irreversible strain and cumulative irreversible strain increased with increasing gas pressure. ④ Under low gas pressure, the strain concentration area of coal samples was mainly a single vertical strain concentration zone. As the gas pressure increased, the local strain concentration zone gradually transitioned from vertical single to disordered and complex. The higher the gas pressure, the more pronounced the strain field fluctuation and the intensity was concentrated in the central region. At high gas pressures, the greater the number of peak points, the greater the strain with increasing gas pressure.

     

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