采区准备巷道层状复合顶板的离层和机理

SEPARATION CHARACTERISTICS AND MECHANISMS OF LAMINATED COMPOSITE ROOF STRATA OF LONGWALL ROADWAY

以澳大利亚一煤矿的现场观测数据为基础，研究长壁工作面采区准备巷道层状复合顶板的离层和扩展特征及离层机理。对3个不同的采矿阶段，即掘进阶段，掘进之后回采之前和回采阶段的巷道顶板离层发生的时问、位置、大小和所对应的地质条件及离层在各阶段的扩展过程和特点进行了研究。从时间上看，巷道顶板离层在巷道成巷之时即出现，其尺寸随着采矿活动的变化而变化。从空间上看，在成巷初期离层在顶板6m范围内分布大致均匀，之后形成2个位于顶板附近和深部的离层区。随着时间的推移，两离层区域逐渐合并，在巷道顶板上方6m范围内形成为巷道高度的2倍的离层区。在成巷初期，最大离层决定着巷道的离层特性。在成巷后期，离层数量则起主导作用。研究结果还显示采区巷道复合顶板的离层机理与各采矿阶段的采矿活动有着密切的关系。另外，顶板各岩层的物理力学特性，岩层的变形与时间的关系和蠕变特性，地下水的影响以及各采矿阶段之前和之后的垂直和水平应力大小等都是导致采区巷道层状复合顶板离层的重要因素。

Based on a separation dataset collected from a comprehensive underground monitoring in a coal mine in Australia, this paper presents the theoretical and analytical work on the roof separation characteristics, propagation and mechanisms of laminated weak strata of longwall roadway associated with different mining activities including stages of heading development, time-dependent, and longwall extraction. Analytical result indicates that roof separation and propagation are strongly related to different stages of mining activities, such as stress concentration and re-distribution in the stages of development and extraction and roof rock degradation and soften in the stage of time-dependent, and each stage involves different separation characteristics and mechanisms. The monitoring data also suggested that the major separation originated almost uniformly with the formation of opening from the roof surface up to 6 m upwards, and then two separation zones were formed in both lower roof strata in coal and upper roof strata in mudstone respectively. The two separation zones subsequently emerged gradually, and the merged separation zone covered from roof surface up to 6 m which is two times of the heading height. The results indicate that the mechanical characteristics of individual roof layers such as weak claystone layers, water effect on mudstone layers and the interface between the layers, as well as the levels of vertical and horizontal stress in pre： and post- stages of mining activities are important factors involved in roof separation mechanisms and control roof separation and propagation process.