摘要
为探究深部煤层底板变形破坏机制,对比分析了不同初始围压、不同加卸载速率下的砂岩应力—应变变化特征、声发射能量事件与强度变化特征,研究了不同条件下的损伤因子、弹性模量和泊松比变化特征。研究结果表明:卸围压速率0.06 MPa/s时,初始围压40 MPa下砂岩弹性模量损伤劣化转折点早于泊松比转折点,而初始围压25 MPa则与之相反。卸围压速率0.04 MPa/s的应力路径下,无论初始围压为25 MPa还是40 MPa,砂岩均因内部积聚大量能量以裂纹快速扩展的形式进行释放,并伴随着应力跌落现象,定义为能量驱动破坏型;初始围压25 MPa且卸围压速率0.06 MPa/s的应力路径下,砂岩内部裂隙扩展充分,内部积聚的能量及时得以释放,应力变化较为平缓,定义为损伤劣化驱动破坏型。初始围压40 MPa且卸围压速率0.06 MPa/s的应力路径下,砂岩前期因内部能量快速释放而出现应力跌落现象,而后受围压限制和轴压加载的作用,逐渐转变为裂隙扩展损伤变形破坏,即由能量驱动破坏型转变为损伤劣化驱动破坏型。
To investigate the deformation and failure mechanisms of deep coal seam floors,we compared and analyzed the stress-strain behavior,acoustic emission energy events,and strength variations of sandstone samples subjected to different initial confining pressures and varying loading and unloading rates.We also examined changes in damage factor,elastic modulus,and Poisson’s ratio under these conditions.The results indicate that,at an unloading rate of 0.06 MPa/s,the onset of elastic modulus degradation under an initial confining pressure of 40 MPa occurs earlier than the change in Poisson’s ratio,whereas the opposite trend is observed at an initial confining pressure of 25 MPa.When the confining pressure is unloaded at 0.04 MPa/s,regardless of whether the initial confining pressure is 25 MPa or 40 MPa,the sandstone undergoes rapid crack propagation as a result of significant internal energy accumulation.This process is accompanied by a sudden drop in stress and is classified as energydriven damage.Under an initial confining pressure of 25 MPa and an unloading rate of 0.06 MPa/s,internal cracks in the sandstone fully develop,allowing accumulated energy to be released gradually,resulting in a more stable stress response.This behavior is defined as damage deterioration-driven failure.In contrast,at an initial confining pressure of 40 MPa and the same unloading rate,the sandstone first experiences a rapid stress drop due to the sudden release of internal energy.Subsequently,the failure mode shifts to crack propagation and deformation,influenced by confining pressure and axial compression,marking a transition from energy-driven damage to damage degradation-driven failure.
作者
张风达
王路
张玉军
樊振丽
张志巍
ZHANG Fengda;WANG Lu;ZHANG Yujun;FAN Zhenli;ZHANG Zhiwei(CCTEG Coal Mining Research Institute,Beijing 100013,China;Shaanxi Shaanmei Caojiatan Mining Co.,Ltd.,Yulin 719000,China;Coal Mining and Designing Department,Tiandi Science and Technology Co.,Ltd.,Beijing 100013,China;Mining Research Branch,China Coal Research Institute,Beijing 100013,China)
出处
《矿业安全与环保》
北大核心
2025年第4期78-86,共9页
Mining Safety & Environmental Protection
基金
国家自然科学基金项目(51704158,51874177)
天地科技股份有限公司开采事业部科技创新基金项目(KCYJY-2023-MS-03,KCYJY-2023-QN-03)。
关键词
砂岩
卸荷劣化
损伤
能量
加卸载路径
底板
sandstone
unloading deterioration
damage
energy
loading and unloading path
coal seam floor
