松散承压含水层的载荷传递作用对关键层复合破断的影响

EFFECT OF LOAD TRANSFER OF UNCONSOLIDATED CONFINED AQUIFER ON COMPOUND BREAKAGE OF KEY STRATA

采用专门设计的物理模拟试验装置及数值模拟试验方法,就松散承压含水层的载荷传递机制及对覆岩关键层复合破断的影响进行深入研究。研究结果表明:松散承压含水层条件下,由于承压水的流动性和补给作用,上覆表土层的载荷通过松散承压含水层均匀地作用于下部基岩上,开挖过程中基岩顶界面上的载荷基本保持恒定,松散承压含水层起到均匀传递载荷的作用;无松散承压含水层时,作用在基岩顶界面上的表土层载荷随煤层开挖而显著降低。在松散承压含水层的载荷传递作用下,作用在基岩顶界面的载荷较大,当基岩厚度较薄时,采场覆岩关键层易产生复合破断。基于松散承压含水层对薄基岩采场关键层复合破断影响机制,很好地解释华东矿区部分矿井在松散承压含水层与薄基岩的特殊条件下采场发生压架事故的原因。

With a specially designed experimental instrument,the mechanism of load transfer within an unconsolidated confined aquifer and its effect on compound breakage of key strata have been studied.The results show that（1） the unconsolidated confined aquifer plays a crucial role in load transfer because of its fluidity and replenishment in time,making the loads of overburden soil evenly transfer into the bedrock through the unconsolidated confined aquifer and the load keep constant during the excavation process;（2） under the condition without unconsolidated confined aquifer,the load on the bedrock will be reduced sharply during the excavation.Therefore,in the process of load transfer within the unconsolidated confined aquifer,the key strata of overburden rock are prone to have a compound breakage when the load on the upper interface of bedrock is great and the bedrock is very thin.Based on the mechanism of the effect of unconsolidated confined aquifer on the compound breakage of key strata,the fully mechanized support crushing accidents taking place during coal mining under the unconsolidated confined aquifer and thin bedrock in some collieries of East China have been well explained.