深部采空区煤层底板滞后破坏特征

张风达

深部采空区煤层底板滞后破坏特征

张风达

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出版历程
- 发布日期: 2020-07-19

Delayed Failure Characteristics of Deep Coal Seam Floor in Goaf

ZHANG Fengda

摘要

摘要: 为分析深部采空区煤层底板滞后破坏特征,运用悬臂梁模型分析裂纹面间锁固段的变形破坏特征,通过试验分析岩样加载至塑性阶段后卸载再加载过程中的体积应变与偏应力的关系,结合煤层底板注水试验实测数据分析深部煤层底板岩体在采空区重新压实过程中的渗透性能变化。研究表明,裂纹面间锁固段变形破坏程度在采动剪切滑移和采动卸荷过程中逐渐增大;处于塑性状态的岩样在轴向应力卸载后再加载至卸载点81 MPa时,体积应变由0.000 56增大至0.001 1;现场实测发现距煤层底板18.19 m处的岩体在工作面推过测点3.6~15.8 m的过程中出现裂纹扩展、变形破坏,在工作面推过测点20.6~30.9 m过程中,底板岩体再次发生变形破坏,说明深部煤层底板在加载至塑性状态后卸荷并重新承载的过程中仍存在变形破坏可能性。
- 加卸载 /
- 重新加载 /
- 滞后破坏 /
- 采空区 /
- 煤层底板
Abstract: To study the delayed failure characteristics of deep coal seam floor in goaf, the deformation and failure characteristics of the locking section between the crack surfaces are analyzed by using the cantilever beam model. The relationship between volumetric strain and partial stress in the unloading and reloading process of rock samples after loading into the plastic stage is analyzed by laboratory test. Finally, the change of permeability of deep coal floor rock mass in the process of goaf recompaction is analyzed with the measured data of water injection test in coal seam floor. The results show that the deformation and failure degree of the interlock section between the crack surfaces increases gradually in the process of mining shear slip and mining unloading; the rock sample in the plastic state is loaded to the unloading point of about 81 MPa after the axial stress unloading, and the volume strain increases from 0.000 56 mm to 0.001 1 mm. Through the field measurement, it is found that the crack propagation and deformation failure appears in the rock mass 18.19 m of the coal floor in the process of the working face pushing through the measuring point from 3.6 m to 15.8 m. Meanwhile, the deformation failure of the coal floor appears again in the process of the working face pushing from 20.6 m to 30.9 m, which indicates that the deep coal seam floor still has the possibility of deformation and failure in the process of unloading and reloading after loading to the plastic state.
- loading and unloading /
- reloading /
- delayed failure /
- goaf /
- coal seam floor

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