Simulation Study On The Failure Law Of Floor Strata Under Different Working Face Lengths With Pressure Mining

In recent years,with a group of progressive depletion of coalresources,some mines began to an extension of lower coal mine, faced with theincreasing exploitation of ground stress.Under threat by the Taiyuan Coal Group limestone moisture, Ordovicianlimestone water pressure is more serious,how to effectively forecast and preventand control of roof and floor water inrush is imminent problem.In this paper,mainly studies the length of the working face,after studying the research statusat home and abroad,relying on engineering geological background of SHOUWANG Coal,do a research of the influence factors of water inrush、miningabutment pressure mechanical model、solid-liquid two-phase flow numericalmodel coupling、hydrophobic roof down.And obtained the following results:(1)Analyzed the causes of floor water inrush,it was caused by floorhydrous,rich aqueous,combination of lithology,geological structure,miningengineering and mining conditions.When calculating the depth of the floor withthe destruction of the impact factor quantifies,help to calculate the depth of thescene of the damage zone. (2)Based on the distribution of the overburden load,the establishment of auniform load and concentrated load characteristics of the mechanical analysismodel,using the theory of elastic mechanics,derive any point along the insideseam floor rock stress expression,Providing theoretical position for breaking thefloor.(3)According to the field of soil mechanics theory slip displacement andLinear regression calculate the damage the floor with depth h1,come to aconclusion that damage depth is8.5~9.5m at the buried depth of450m;According to the thin plate theory to calculate the effective isolation hosefrom the limit of water pressure,the h2of thickness of impermeable tapeobtained by Inverse;Mainly based on geophysical means to judge the thicknessof lead-liter h3.(4)Using numerical simulation software,when under pressure when notcoupling and coupling mining calculate the stress distribution in the floor, thegreatest damage depth, pore water pressure were compared,obtained conclusionof under the condition of considering the coupling damage depth of the baseplate and stress is larger,may be more prone to sudden water.(5)According to the in-situ stress measurement, the depth of the failuredepth of the bottom plate is determined by h1, theoretical calculation andnumerical simulation is similar，and the depth of the damage depth is predictedby the different working surface length.