薄层复合顶板爆破损伤试验研究

Experimental Study on the Mechanism of Thin-Layered Compound Roof

薄层复合顶板爆破掘进时易发生顶板离层冒落失稳造成冒顶事故,为研究该类顶板在爆炸应力波反复作用下损伤变化规律,针对东荣二矿中一上采区17煤右三下料道特殊层状结构,基于声波测速原理,利用RSM-SY5智能声速测试系统,在爆破掘进方式下对巷道顶板损伤进行了现场测试.研究表明:每一次爆后顶板各测点声速总比爆前有不同程度的降低,其中第1次和第2次爆后声速降低明显.根据声速变化大小可知在0.6,2.4m处发生离层的可能性最大.而各测点处的损伤程度随着爆破次数的增加呈递增变化;按照损伤阈值Der=0.19,顶板损伤范围在0～3.6m之间.随着各测点离爆破工作面距离的不断增加损伤累积呈非线性增加,而且损伤并不是随着测点深度变化呈线性递减的;同时顶板各测点损伤变化率呈非线性递减,在测点置后工作面16m处,顶板损伤变化率处于一个较低的水平.

Roof caving accidents happens easily due to the instability during driving face＇s blasting excavation for the thin-layered compound roof. Aiming at the geological condition of the thin-layered compound roof in the 2nd mine of Dongrong Mining Area, we use the RSM-SY5 intelligent sound wave apparatus to conduct an experiment for the roadway roof damage during the excavation blasting so as to study the rule of top roof damage variation. The results show that the sound wave velocity of each point in the roof is reduced in varying degrees after each explosion, and the sound speed wave of the 1st and the 2nd time is reduced significantly. According to the variation of sound wave speed, the top roof is likely to delaminate at the points of 0.6 m and 2.4 m of the drill hole. The measuring points blast damage increases with the increase of blasting time and the roof damage scope is between 0 and 3.6 m of top roof if the damage threshold is Der=0.19. The damage accumulation increases non-linearly as the driving face moving while the damage decreases linearly as the increase in depth of measuring points. Meanwhile, the roof measuring point＇s damage variation rate decreases non-linearly. And the roof damage variation rate is at a low level when the measuring points located 16 m behind of the driving face.