爆破载荷作用下控制孔增透作用机理试验研究

Tests for control hole's enhanced permeability mechanism under blasting load

为了研究爆破载荷作用下控制孔增透作用机理,在实验室搭建爆破模拟试验系统,设计了有控制孔和无控制孔两种不同的模型试件,以煤体工程分类为依据结合构造煤物理力学特性利用相似材料配比加工制备尺寸为300 mm×300 mm×300 mm的两种模型试样进行爆破模拟试验。利用高速摄像仪记录试样完整的裂纹萌生、扩展、贯通直至试样破坏的全过程,采用超动态应变仪监测煤岩层的应变信号,利用网络并行电法仪CT反演爆破前后模型试件电阻率的变化,分析两种模型试件在爆破载荷作用下裂纹扩展、动态力学和电性参数特性,进一步揭示了控制孔在深孔控制爆破卸压增透中的作用。结果表明,爆破载荷在固定端("硬"材料)产生反射压缩波,在控制孔全部反射成拉伸波;爆破试样在冲击波、应力波、爆生气体的共同作用下产生两段主要波形,测点径向应变峰值与切向应变峰值相近;爆破前后煤岩电阻率产生异常变化,前后的平均异常系数为6~9。研究成果可用于现场工程实践中利用深孔控制爆破技术卸压增透防治煤与瓦斯突出等瓦斯灾害。

In order to study the enhanced permeability mechanism of control hole under blasting,an analog test system of blasting in a laboratory was built. A test model with control hole and other one without control hole were designed.Two models with sizes of 300 mm × 300 mm × 300 mm were built based on coal engineering classification and coal physical and mechanical characteristics. The blasting analog tests were conducted on the two models,their crack initiation,propagation,perforation and destruction processes were recorded using a high-speed camera. The strain signals of coal seam were monitored with a super dynamic strain gauge. The electrical resistivity changes of the models before and after blasting were inverted with a network parallel electrical instrument. The models ' crack propagation,dynamic and electrical parameters characteristics were analyzed under blasting load. The actions of control hole in deep-hole control blasting,pressure relief and permeability enhancement were further revealed. The results indicated that blasting load produces reflected compression waves at the fixed end( hard materials) and they are reflected into tension waves at a control hole; two models produce two main waveforms under the combined action of shock wave,stress wave and detonation gas; the measured point's radial strain peak value is close to its tangential strain peak one; coal rock resistivity has an abnormal change before and after blasting,the mean abnormal coefficient before and after blasting is 6 ~ 9; the results can be used to prevent coal and gas outburst with the deep-hole control blasting technology in engineering practices.