Experimental and numerical study of failure behavior and mechanism of coal under dynamic compressive loads

A comprehensive understanding of the failure behavior and mechanism of coal is a prerequisite for dealing with dynamic problems in mining space.In this study,the failure behavior and mechanism of coal under uniaxial dynamic compressive loads were experimentally and numerically investigated.The experiments were conducted using a split Hopkinson pressure bar(SHPB)system.The results indicated that the typical failure of coal is lateral and axial at lower loading rates and totally smashed at higher loading rates.The further fractography analysis of lateral and axial fracture fragments indicated that the coal failure under dynamic compressive load is caused by tensile brittle fracture.In addition,the typical failure modes of coal under dynamic load were numerically reproduced.The numerical results indicated that the axial fracture is caused directly by the incident compressive stress wave and the lateral fracture is caused by the tensile stress wave reflected from the interface between coal specimen and transmitted bar.Potential application was further conducted to interpret dynamic problems in underground coal mine and it manifested that the lateral and axial fractures of coal constitute the parallel cracks in the coal mass under roof fall and blasting in mining space.

表面活性剂协同作用下湿式过滤除尘实验研究

选取无烟煤粉为对象,对表面活性剂的相关性能以及无烟煤粉的润湿性进行研究,在此基础上设计并搭建了湿式纤维栅除尘系统,研究不同风速、喷雾压力、纤维栅目数以及复配表面活性剂的种类对除尘效率的影响。实验结果表明,表面活性剂可以有效降低水的表面张力,使得煤粉更容易被湿润;在除尘系统还未添加表面活性剂时,干式纤维栅对粉尘的单一过滤效率较低;添加喷雾装置后,除尘效率随喷雾压力的增大先提高,后趋于稳定,且总体效率均明显高于单一纤维栅除尘条件下的效率;纤维栅目数和除尘效率呈正相关,而当风速大于0.7 m/s后,由于纤维网上形成的水膜较多,会对风速产生一定的阻力,此时,风速对除尘效率的变化影响不明显;添加表面活性剂之后,发现LAB-35和X-100混合表面活性剂溶液的除尘效率最高,达到97.03%。