Research On Abutment Pressure Distribution Of Coal Pillar Under Effect Of Vermiculite Compaction In Goaf

In this paper,the combination of laboratory test,mechanical model analysis,and numerical simulation research,a comprehensive and in-depth study of the compaction characteristics of vermiculite in the gob area,reveals the effect of vermiculite compaction in the goaf and its effect on the pillar pressure.The distribution of the law,the main results are as follows:The compaction characteristics of the broken vermiculite were studied to study the compaction characteristics of the vermiculite with different particle sizes.The Matlab simulation was used to obtain the compressive modulus during the compaction process of a single particle size gradation and mixed particle size grading gangue.The exponential function relation between the compaction rate and the compaction rate was used to invert the compaction process of 10-20 mm vermiculite in the laboratory compression test by the PFC3D software.The control parameters of inversion simulation were obtained by trial and error method.On this basis,the size effect of the compression cylinder is studied.When the diameter of the compression cylinder is expanded to 600 mm,the increase in the diameter of the compression cylinder has negligible influence on the compaction characteristics of the vermiculite.The force model of the lateral roof structure of the goaf is established,and the compaction characteristics of the meteorite in the goaf and the formula of the support reaction of the meteorite support and the distribution of the support reaction force are given.According to the elastic foundation beam theory and the limit equilibrium theory,The effect of the compaction effect of the goaf on the stress distribution law of the coal pillar was studied,and the expression of the stress of the coal pillar under the different maximum compaction rates of the vermiculite in the goaf was obtained.The peak value of coal pillar stress decreases with the increase of the maximum compaction rate in the goaf area;the FLAC3D numerical simulation method is used to compare and study the different maximum compaction rate and different stress monitoring line position in the goaf,and the meteorite and coal pillars in the goaf are compared.And the basic top of the vertical stress changes.The stress of the meteorite in the goaf is indexed back to the stress value of the original rock,and the supporting pressure of the coal pillar occurs at the peak of 4-5m in front of the coal wall.The greater the maximum compaction rate of the meteorite in the goaf,the faster the vertical stress recovery rate of vermiculite in the goaf,and the smaller the peak support pressure on the pillar.The numerical simulation results are basically consistent with the theoretical analysis.