| The Gob-side Entry Retaining(GER)has obvious advantages in improving the stress environment of surrounding rock and utilization rate of coal resources.Retained and reuse of roadway affected by twice mining of adjacent working faces,whether the roadside support body can adapt to the multiple load changes caused by overburden activities is the key to the success of GER.The effect of retaining roadway can be improved by using Concrete Filled Steel Tube(CFST)as support body in columnar GER,and the non-continuous arrangement of support body will cause the change of load transfer mode and stress condition of roof.In this thesis,the interaction between roof and supporting body,the deformation law of surrounding rock,the characteristics of overburden structure and roof control were studied systematically by theoretical analysis,numerical simulation,similarity test and field practice.The main research achievements are as follows:(1)The mechanical model of the lateral roof and the roof between two columns was established.By means of theoretical analysis and FLAC-PFC coupling calculation,the axial loaded characteristics of CFST was studied,and the adaptability of the columnar roadside support body and the roof movement laws were verified.(2)A numerical calculation model of columnar GER was built to studied the dynamic evolution and static distribution of mine pressure in the process of working face mining.The stress evolution and deformation characteristics of surrounding rock and the variation law of supporting resistance under twice mining were analyzed.(3)Similarity test model of columnar GER considering twice mining was established to analyze the roadway loaded characteristics influenced by the breaking form of the overburden structure from the point view of “large structure” of mine strata.The migration law of overburden and the stress evolution law of different roof regions were obtained during twice mining processes.(4)A Columnar GER roof control system which combines reinforcement support,auxiliary support in retaining roadway operation,core roadside support and isolation support for goaf was proposed.And the control effect of retained roadway roof was comprehensively evaluated by means of mine pressure monitoring.The dissertation includes 76 papers,12 tables and 88 references. |
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