Abstract: In response to the issue of prevention of support crushing and water inrush disaster during mining under unconsolidated confined aquifer, a specialized simulation experiment set based on the mechanism of aquifer load transfer has been designed and the influence of occurrence characteristic of unconsolidated confined aquifer on its property of load transfer and key stratum compound breakage has been studied. The result indicates that load transfer effect on the unconsolidated confined aquifer is closely related to its framework grain characteristic. The larger the skeleton granule diameter is, the simpler the component is, and the better the property of flowing and replenishment is. Therefore it can transfer load to top overburden continuously and uniformly and make the load on top of overburden larger, which easily causes overburden integral breakage and results in support crushing and water inrush disaster. While the smaller the framework grain diameter is, the more complex the component is, and the poorer the property of flowing and replenishment is. Load applying on top of overburden can reduce during mining and aquifer load transfer coefficient can become smaller. Therefore, key stratum breaks layer by layer and hardly causes support crushing and water inrush. Calculating method of load transfer coefficient of unconsolidated confined aquifer has been confirmed. Load transfer coefficient should be 0.83 to 0.94 in alluvial and pluvial fan area of Qidong coal mine, while non-alluvial and pluvial fan area should be 0.69 to 0.71.

Key words: unconsolidated confined aquifer, load transfer, key stratum compound breakage, support crushing and water inrush