模拟层状岩层样品失稳的冲击倾向性实验研究

Experimental research on bump proneness of simulated layered rock specimens

为了弄清顶底板和煤体强度对煤岩系统冲击倾向性的影响以及三者之间的联系,探明静载条件下坚硬的顶底板能否引起冲击矿压。在实验室利用混凝土模拟8种不同强度的煤岩组合,利用MTS试验机在静载条件下对样品做单轴压缩试验,以动态破坏时间,单轴抗压强度和破坏时声音大小评估样品的冲击倾向性。实验结果表明:煤层决定了煤岩系统的强度与冲击倾向性,坚硬的顶底板可以增加软弱煤层的冲击倾向性,软弱的顶底板也可以减小坚硬煤层的冲击倾向性;顶底板对系统冲击倾向性的影响与煤体的性质紧密相关:当煤体软弱,坚硬底板能限制其变形,尤其是与坚硬顶板形成加持作用能显著提高系统冲击倾向性;当煤体坚硬,底板强度对系统冲击倾向性影响很小,顶板强度的增加能增强系统的冲击倾向性;当底板和煤体都软弱,顶板强度对系统冲击倾向性影响很小;在静载条件下,单纯坚硬的顶底板并不是引起冲击矿压的必要条件。

In order to make clear bump proneness with different strength of roof,coal and floor and whether strong roof and floor can trigger bump under static loading condition.Layered concrete specimens were prepared to simulate coal and rock of different strength.Uniaxial compression tests were conducted for concrete specimens in the MTS machine under static loading condition.Index of dynamic failure time,sound pressure level and uniaxial compression strength were used to assess the violent degree of failure which could reflect the bump proneness.The results show that coal is the crucial factor to determine the strength and bump proneness of the rock and coal system.Strong roof and floor can increase the bump proneness of weak coal,while,weak roof and floor can decrease the bump proneness of strong coal.In addition,the affect of roof and floor is closely related to the property of coal.When the coal is weak,strong floor can confine its deformation,especially with strong roof,the clamping action can increase bump proneness obviously.When the coal is strong,the affect of floor is negligible,but a stronger roof can increase the bump proneness;When both coal and floor are weak,the affect of roof is little.Under static loading condition,only strong roof and floor cannot trigger coal bump.