压头角度对点载荷作用下煤岩体内的应力分布影响研究

Study on the influence of indenter angle for the stress distribution in coal and rock under the action of point load

为研究压头角度造成点载荷试验结果差异的原因,采用理论分析和数值模拟方法研究压头角度不同时点载荷作用下煤岩体内部的应力分布规律。研究发现:在不同角度压头作用下煤岩体内部均产生压应力和拉应力;在垂直和水平剖面上,垂直应力分别呈现“倒置双峰形”和“圆环状”;加载点附近煤岩体受到各个方向的压应力作用,且随着与加载点距离的增大而减小,在加载点一定距离内受到垂直加载轴方向的水平拉应力和竖直拉应力,水平拉应力区呈圆球状。研究不同角度压头作用下煤岩体的应力状态,发现压头角度对应力分布形式影响较小,但在小角度压头作用下煤岩体内应力集中更加强烈,进而影响煤岩体试样破坏时应力值。

In order to study the reasons for the difference of point load test results caused by indenter angle,the stress distribution law in coal and rock mass under the action of point load with different indenter angle was studied by theoretical analysis and numerical simulation.The results show that compressive stress and tensile stress are generated in coal and rock mass under the action of different indenter angle.The vertical stress presents an“inverted double peak shape”and a“circular shape”in the vertical and horizontal sections,respectively.Near the loading point,the coal and rock mass is subjected to compressive stress in all directions,and decreases with the increase of the distance from the loading point.The horizontal tensile stress and vertical tensile stress in the direction of the vertical loading axis are subjected within a certain distance from the loading point,and the area of horizontal tensile stress is spherical.The stress state of coal and rock mass under the action of different indenter angle is studied.It is found that the indenter angle has little influence on the form of stress distribution,but the stress concentration of coal and rock mass is more intense under the action of small indenter angle,which further affects the stress value of coal and rock mass sample when it is damaged.