In order to study immediate roof of silty mudstone early to be taken place roof fall under effect of fissure water, presented en-riched coal roadways instability mechanism by the means of synthesizing practical, sampling laboratory tests and theory analysis. This mechanism is that some crack produce by excavation connect aquifer of main roof, microstructure of silty mudstone are contents of lots of hydrophilicity minerals and fracture, meanwhile, and then silty mudstone produce highly expansion stress and make disintegration after absorbing water. Basis of bolt destroyed and highly expansion made the water-enriched roofs instability. Meanwhile, for this mechanism, proposed a technology for controlling roofs stability, including water retention, optimizing sectional drawing of roadway and high pretensioned stress. Field test indicates that semicircular arch roadway, hydrophobic holes and combined support system with high pretensioned stress bolts can maintain the roof stability in this kind of coal drifts.%为了研究煤层巷道粉砂质泥岩直接顶受基本顶裂隙水侵蚀后,巷道掘进过程中易于发生冒顶事故的原因,通过现场调研、取样、实验室试验和理论分析相结合的综合研究手段揭示出富水煤层巷道顶板失稳的机理在于:巷道开挖后产生的顶板裂隙形成了直接顶与基本顶含水层之间连通的通道,使得微结构裂隙发育和含有较高的亲水性矿物粉砂质泥岩吸水,其吸水后产生了较高的膨胀应力,并在三向受力状态下发生崩解、破坏,锚杆承载基础弱化和较高的膨胀应力引起了煤层巷道顶板失稳.同时针对富水煤层巷道顶板失稳机理,提出了通过减少顶板水运动对围岩的破坏、优化巷道断面和高预应力来实现该类巷道顶板的稳定.工程实践表明,采用半圆拱巷道、合理布置疏水孔以及高预应力锚带网索组合支护体系可确保对该类巷道顶板的有效控制.
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