Failure Mechanism And Support Optimization Of Floor Roadway Under Complex Coal Body

In China,especially in the south,there are a large number of coal mines with weak lithology.The geological conditions of roadway surrounding rock are very complex and the stability of surrounding rock is poor.Therefore,under this condition,the roadway is difficult to maintain and support.In this case,the study of the failure mechanism and support technology of the surrounding rock of the floor roadway under the complex coal body can provide a basis for controlling the stability of the surrounding rock of this kind of roadway and designing a scientific and effective support scheme.In this regard,this paper takes the East floor lane of 2254 Puxi well of Jiahe mining company of Hunan coal industry group as the research object,and mainly studies the following aspects:(1)X-ray diffraction test of surrounding rock composition and borehole peeping were carried out in 2254 East floor roadway.It is found that the main mineral composition is siderite(51.34%),which is easy to be weathered or hydrolyzed in the air and change the original properties.At the same time,it contains 9.52% kaolinite minerals.Kaolinite has low hardness and is easy to soften in case of water.Through drilling peep,it is known that the surrounding rock of the roadway exists in layers,and a large number of cracks appear in the shallow surrounding rock of the roadway.(2)The in-situ stress test results show that the in-situ stress field in Jiahe mining area is dominated by horizontal stress(12.8MPa),the minimum principal stress is vertical principal stress(6.0MPa),and the lateral pressure coefficient is as high as 2.1.At the same time,the included angle between the principal stress and the axial direction of the floor roadway is about 90°,which is the reason for the serious damage of the two sides of the roadway.(3)Based on the gas drainage drilling data of 2254 East floor roadway,the geological occurrence model of complex coal seam above the roadway is constructed by using Sketch Up and rhino software,the FLAC3 D numerical calculation model under the occurrence conditions of complex coal seam is further obtained,the failure mechanism of surrounding rock of Floor Roadway after complex coal seam mining is simulated,and the optimal support scheme is put forward.(4)According to the actual situation of 2254 East floor roadway and combined with the numerical simulation results,a comprehensive support scheme of "bolt,metal mesh,shotcrete,anchor cable,hollow grouting anchor cable and full section grouting" is proposed.After the implementation of the scheme,the roadway surrounding rock deformation of the support section is monitored for 12 months.The monitoring data verify the effectiveness of the support scheme and ensure the long-term stability of the roadway.