Experimental study on feature parameters of fluid-solid coupling model ofunderground reservoir in shallow depth seam

A rock mass migration,crack evolution and seepage features caused by the seam mining could be highly affected to the design and construction of the underground water reservoir.In order to get the physical features and parameters of the surrounding rock mass in the underground water reservoir,an experiment study was conducted on a fluid-solid coupling model of the similar material.In combination with the hydrogeological and mining conditions of the typical shallow depth seam,the fluid-solid coupling model of the 3D similar material was established.With the monitoring and measuring on the variations of the roof subsidence,coal pillar stress,aquifer seepage pressure and other feature parameters during the mining and excavation process of the seam,a study was conducted on the broken rock mass migration,crack evolution law and the disturbance rock seepage features varied law during the mining process of the seam.the experiment results showed that after the excavation of the seam,the overburden strata above the coal pillar would form a inverted step structure and the coal pillar stress would be firstly increased and then decreased.The rock strata of the roof before and after experienced a dynamic evolution process of “bending subsidence - crack development - broken collapse”.The crack development degree of the rock strata would determine the number of the formed water flowing crack zone.The seepage pressure decreased rate of the rock strata could be applied to characterize the crack development degree of the rock strata.A large area collapsing of the rock strata would lag behind the formation of the water flowing cracks.A sudden changed seepage pressure of the aquifer would be before the sudden subsidence occurred.A sudden reduced seepage pressure of the aquifer could be one of the foretastes to the roof weighting and collapsing.