深部开采底板裂隙扩展演化规律试验研究

 为进一步研究深部底板岩体的破裂失稳机制，基于自主研制的高水压底板突水相似模拟试验系统，建立深部承压水上含小断层底板采动裂隙演化及导水通道形成的模型，通过在底板不同深度布设应力传感器和位移监测点，研究底板和断层附近岩体随工作面开采的应力及位移变化规律，反演得到底板及断层采动裂隙的发育及扩展演化规律，为深部开采工作面突水机制的研究提供了一种新的思路。结果表明：工作面开采过程中，底板岩体的受力变化规律主要有2种：(1) 开切眼左侧煤柱底板岩体的应力增量出现先增大后减小的变化趋势；(2) 采场底板岩体的应力增量出现先增大后减小至零再反向增大的变化趋势。深部底板岩体的采动裂隙主要在开切眼、采空区中部和回采工作面3个部位产生，裂隙类型以竖向张裂隙、剪切裂隙和层向裂隙为主，且在主要裂隙附近衍生出一些细微的小裂隙。距煤层较近的断层上、下盘岩体受到的应力差较大，断层上盘在强剪应力差的作用下形成了一条与断层走向平行的剪切裂隙，加快了断裂面破碎岩体的相对滑动程度，促进了断层的活化。

Experimental study of floor cracking under deep mining

In order to study the failure mechanism of deep floor rock，a model of mining cracking and conduit formation in floor rock with small faults was established based on the test system developed in-house with high water pressure to simulate the floor water inrush. The stress and displacement sensors were set up at different depths of the floor，and the stress and displacement of the floor and the fault rock around the mining face were studied. The crack development and propagation in the floor and fault rock was derived with the inverse simulation. Two trends of the stress in the floor rock during mining at the working face occurred. In the first case，the stress increment in the floor rock under the pillar on the left open-off cut increased at first and then decreased. In the second case，the stress increment in the floor rock under the stope increased at first，then decreased to zero and finally increased at the opposite direction. The deep mining cracks mainly appeared in the corresponding floor of open-off cut，goaf and mining working face dominated by the vertical tensile cracks，shear cracks and layer cracks. Some small cracks were generated from the tips of the main crack. The larger stress differences were formed in the hanging wall and the footwall rock of fault close to the coal seam. A strip of long shear crack parallel to the fault strike was presented in the fault hanging wall due to the large shear stress difference，which promoted the sliding and the fault activation.