【摘要】 针对大采高工作面煤壁围岩应力场特点,利用卸荷岩体力学理论、断裂力学理论建立了煤壁开挖卸荷效应模型,分析了在卸荷应力场作用下煤壁失稳机理。结果表明:煤层开采过程即是对煤岩体的卸荷过程,煤壁围岩应力场将转变为由原始应力、卸荷应力构成的卸荷应力场;在卸荷应力场的作用下,煤壁中的裂纹将以复合型裂纹形式发生失稳、扩展、联合,并逐渐演化为楔形体结构;楔形体的稳定性与顶板压力P0、卸荷力T、结构面交线倾角φ呈反比关系;通过增大护帮力Ph、提高工作面支架初撑力、提高煤体内聚力C等方法,能够有效控制煤壁片帮事故的发生,有利于大采高工作面的安全回采。更多还原

【Abstract】 According to stress characteristics of surrounding rock of working face with a large mining height, the coal wall excavation unloading effect model is established by using the unloading rock mass mechanics theory and the fracture mechanics theory to analyzes coal wall instability mechanism under the condition of unloading stress field. The research results show that the process of mining is the process of unloading coal and rock mass; the stress field changes to the unloading field consisted of the in-suit stress and unloading stress; under the effects of unloading stress field, the cracks in the coal wall would change into the mixed mode cracks. Thus, the instability, expansion and union of such cracks would be formed and the wedge structure would be expected; The stability of "wedge" has an inverse relationship with the stability and roof pressure P0, unloading load T and structural plane intersection angle φ. By increasing the coal rib protection force Ph or the working face supporting force or the coal internal cohesion C, it is good for controlling the accidents of coal rib fall and maintain the safety production in the working face with the large mining height.更多还原