基于能量计算的预掘回撤通道顶板下沉量分析

Analysis on roof sag of pre-driven recovery room based on energy calculation

采用预掘回撤通道技术的综采工作面在末采阶段易发生顶板大变形而引发压架事故。本文基于工作面贯通后的3种基本顶破坏形式,建立了不同的回撤通道顶板力学模型,通过分析顶板变形过程中的能量释放与做功过程,求得不同基本顶破坏形式下的回撤通道直接顶下沉量。结合张家峁煤矿N14201工作面回撤通道顶板大变形案例,分析了不同顶板力学模型的影响因素,发现基本顶破断位置、关键块及其上覆岩层厚度、关键块回转角和支护强度对回撤通道顶板下沉量影响显著,确定了张家峁煤矿N14201工作面发生压架事故的原因,即基本顶在保护煤柱上方4~6 m范围内破断以及上部3^(-1)煤层开采导致主关键层破断失稳。

The fully mechanized mining face adopting pre-driven recovery room is prone to large roof deformation at the final mining stage,which will lead to support crushing accidents.Based on the three main roof failure forms after longwall face entered recovery room,this paper established different mechanical models for roof sag of the recovery room.By analyzing energy release and work process in roof deformation,this paper obtained the immediate roof sag of recovery room under different main roof failure forms.Taking the large roof deformation and support crushing accident of recovery room in the N14201 longwall face of Zhangjiamao Coal Mine as example for analysis,this paper analyzed the influencing factors of the models and found that the main roof break position,the thickness of key block and its overlying strata,the rotation angle of key block and the supporting intensity have significant impact on the roof sag of recovery room.The research results confirmed that the reason for the support crushing accident in N14201 longwall face of Zhangjiamao Coal Mine:the main roof is broken within 4~6 m a-bove the protective coal pillar,and the main key stratum is broken and unstable due to the mining of upper 3^(-1) coal seam.