Abstract: In this paper, to research the stability of overlying water-resistant strata and prevent the roof water inrush accidents as well as implement water-preserved-mining, we regarded the water-resistant strata composed by only one rock stratum as clamped rectangular thick plate on foundation, and took the support effect of broken rock mass under the water-resistant strata into account, then deduced the deflection and stress expression according to energy method, and obtained the stress distribution characteristics of overlying water-resistant strata, as well as the variation rule of critical load along with working face advancement. In addition, combined with specific engineering practice, the stability of overlying water-resistant strata was analyzed by numerical simulation. The results indicate that: 1) after coal seam mining, the stress of overlying strata reaches the maximum value in the middle of longer boundary of the plate, where the rock is easy to be damaged; 2) the supporting effect of broken rock mass have important influence on the stability of overlying water-resistant strata, that is, the thinner the mining thickness is, the stronger the supporting effect of broken rock mass to the overlying water-resistant strata is, and the more difficult the water-resistant strata to be broken. The research results can provide some reference for the prevention of roof water inrush and water-preserved-mining practice.

Key words: water-resistant strata, mechanical model, plate theory, energy method