大尺度冲击性煤体电阻率变化规律的实验研究

The Experimental Study on the Apparent Resistivity of Large-scale Coal Samples with Burst Tendency

在未加载条件下对大尺度煤样的电阻率测试结果表明,在自然状态下煤样的电阻率较大;经过浸泡后其电阻率明显下降.在单轴压缩条件下的大尺度冲击性煤样电阻率实验表明,电阻率变化曲线整体上成不对称的"凹"型,基本符合二次曲线;煤样电阻率随压力增加逐渐减少,当达到一定的应力值时,电阻率达到最小值;继续加载,电阻率将升高,直到完全失稳.1#、3#和4#煤样单轴抗压强度与其受载过程中的视电阻率变化存在一定的正相关性;受载煤体的电阻率变化与其变形破裂过程中的裂隙分叉、发育、汇合贯通密不可分;兼有剪裂和拉裂特点的破坏类型可能是大尺度煤样较常见的破坏形式.

In this paper, the characteristics and rules of the apparent resistivity of large - scale coal samples with burst tendency are studied. Experiment results show that the apparent resistivity of coal samples are relatively large in natural state and decrease significantly after water immersion, and the apparent resistivity curves of coal samples in the uniaxial compression are like asymmetric concave type, which is basically in line with quadratic curve. The positive correlation between the uniaxial compressive strength and the apparent resistivity changes of 1 #,3#,4# coal samples is studied and the apparent resistivity changes of coal samples under load are closely associated with the bifurcation, expand, confluence and connection of their cracks. The failure type with the characteristics of both shear fracture and tension crack have a good potential in the fundamental failure form of the large -scale coal samples.