采空区顶板见方垮落的覆岩空间结构特征及形成条件

Spatial structure features and formation conditions of square-caving overlying strata in gob roof

见方垮落是工作面采空区顶板的一种特殊形式垮落,基于覆岩空间结构理论及薄板结构模型,对其覆岩空间结构特征及形成条件进行研究。顶板见方垮落实质为某关键层初次整体垮落,形式呈正"O-X"破断,其形成条件极为苛刻,需顶板结构及强度、区段煤柱特性、采空区边界条件、工作面宽度、工作面推进距离等因素满足对应关系。判别工作面见方垮落时,需从采区内首采工作面开始,依次计算各工作面回采后关键层的破断情况。工作面宽度越大,关键层见方垮落所需的关键层厚硬程度更高,这是多数工作面所不能满足的,而将冲击地压工作面见方区域均划定为冲击危险区往往偏于保守。

Square caving is a special form of collapse in gob roof of working face.Based on the overlying strata spatial structure theory and the thin plate structure model,its spatial structural characteristics and formation conditions are researched.Roof square caving is essentially the initial overall collapse of the key layer with the breaking form of positive＂O-X＂.The formation conditions for it are extremely harsh,which need many factors to satisfy the correspondence,such as roof structure and its strength,pillar features,goaf boundary conditions,working face width and advance distance.To distinguish the square caving,it needs to calculate in order the collapse characteristics of key strata in each after-mining face from the initial working face in mining area.The larger the width of working face,the thicker and harder the key strata for square caving,which can not be met by majority of working faces,and it is often conservative to determine all the square areas as rock burst hazard areas.