考虑弹性核作用下的冲击地压形成机理模型试验

使用CCD相机搭建实验图像数据采集系统,采用花岗岩模拟坚硬顶底板、红砂岩模拟软岩层组合成岩层结构,近似还原顶板来压过程中软岩层的变形破坏过程,研究帮部"弹性核"对冲击地压至灾的影响机制。研究结果表明:(1)上覆顶板来压时,可将软岩层划分为塑性破坏区、弹性承压区、原岩应力区,弹性承压区易形成较大的弹性核。(2)软岩层变形能在弹性承压区大幅度积累,其积累过程是波动式上升的;在峰值荷载前,变形能积累和释放的频率加快;达到峰值荷载时,弹性承压区变形能存在明显的释放过程。(3)冲击地压发生时,塑性破坏区冲击并反作用于临近岩体使其短暂收缩。(4)冲击地压是一个渐进性的过程;一方面,由于水平约束的消失,弹性承压区的受力状态由水平方向受约束的压缩状转入单轴压缩态,导致其承载能力减弱;另一方面,承载区面积快速减小,导致软岩层承压区域承担的竖向荷载突增;两者共同作用导致冲击地压出现渐进性的冲击和破坏。

Experimental study on development mechanism of coal bump considering the elastic core effect

Construction of experimental image data acquisition system with CCD camera.Granite and Red sandstone were used to simulate strata structure.The granite was used to simulate Hard-Roof and Red sandstone was used to simulate soft rock.Restore deformation and failure process of soft rock strata during roof weighting to research the effect of elastic core.The results show that:(1)When the roof weighting,soft rock strata can be divided into plastic yield areas,elastic confined zone and natural stress zone.The elastic confined zone easy to form elastic core.(2)Lots of energy can be accumulate in elastic confined zone,and the deformation energy of elastic confined zone is fluctuating growth.Before peak load,the fluctuation frequency of deformation energy is increased.Deformation energy have obvious release process when the peak load is reached.(3)When the coal bump occurs,plastic yield areas lash and cause neighbouring mass contract.(4)Coal bump is a gradual process.The fade of horizontal constraints result the stress state get into uniaxial compression state and weaken the bearing capacity.The reduce of bearing area cause vertical load sudden increase.Progressive failure of coal bump is a combination of two aspect.