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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.
In the blasting of thin-layer composite roof, prone to roof fall caused by roof falling instability and causing roof fall accident. In order to study the variation regularity of damage during the repeated stress wave of roof explosion, Under the special stratified structure of the undercut, based on the theory of acoustic velocity, the roof damage of the roadway was tested in the blasting excavation mode by RSM-SY5 intelligent sound velocity test system.The results show that the sound velocity ratio The explosion velocity decreased obviously, the sound velocity decreased obviously after the first and the second explosion.Based on the change of the sound velocity, the probability of delamination was the highest at 0.6 and 2.4m, while the damage degree According to the damage threshold Der = 0.19, the roof damage ranged from 0 to 3.6m. As the distance from each blasting point increased, the damage accumulation increased non-linearly, and the damage Not linearly decreasing with the depth of the measuring point. At the same time, the rate of change of damage at the measuring point of the roof decreases non-linearly. At 16m of the working face after the measuring point is set, the rate of damage of the roof is at a lower level.