Similar Materials Simulation Analysis On The Waterproof Pillar Of Coal Seam Mining Goaf Beside Fault

This paper employs the method of Similar materials simulation and studies thepressure changes of coal seam beside fault zone in order to discuss the reasonablesetting of waterproof pillar beside fault zones. The main content of the paper is asfollows:1. An Similar materials model with the volume of3m×0.3m×1.1m wasproduced based on the geological structure and mechanical properties, to simulatestress changes and deformation characteristics of surrounding rocks in the processof coal mining under different levels of coal thickness, thus to organize andanalysis data captured by the experiment and phenomenon observed.2. Effects on pressure changes and deformation under different levels of coalthickness have been concluded:1) The process of coal mining would push upper rock of the fault movetowards the goaf, causing normal pressure decrease on the fault surface. While thedecrease area was determined by the thickness: when it is2m thick, normalpressure on the fault surface65m higher than the coal roof is less than the initialstress; when it is6m thick, normal pressure on the whole fault surface20m higherthan the coal roof is less than the initial stress;2) The thicker it is, the larger is the tensile strain towards working face. Whileon the same test spot, when the thickness changes from2m to6m, the tensile strainwould become2to9times larger.3) The displacement value of the rock mass will become larger with theincrease of the thickness, while no linear relationship has been discovered, for inthis simulation, it becomes3times thicker but the displacement1to2times larger.4) The effect on unstability of the fault zone by coal mining increases with thethickness. When it is2m thick, the final status of tensile crack is57m away fromthe roof. While it is6m thick, the separation fracture is23m away from the roof.3. This paper concluded the effect on pressure distribution and deformationunder pillars of different widths (with the thickness of2m): 1) With the decreases of the coal pillar width, the pressure on coal seam roofwhich is in front of the working face increases significantly, and the location ofpeak pressure moves towards the forward coal-rock mass, and the narrower the coalpillar width is, the more the pressure increases. The peak pressure appears in acertain distance on the working face promoting direction.2) During the process of coal mining, the displacement value of rocks ondifferent heights10m away from the fault surface will change from relativelyhigher level, with the shortening of waterproof pillar. When a sudden changeoccurred in displacement value, it increases with a tiny amount or stay the samebecause of the supporting force casted on the strata by upper rock of goaf.4. The flaws existing in the waterproof pillar formula of the regulation werecompared and analysised based on the stress rules and deformation situationobtained from the experiment.