| Although China has vast territory and abundant resources,there is still much coal and little gas,so the traditional general mining face needs to set up safety coal pillar,which is easy to cause resource waste.Therefore,the proposal of automatic roadway formation technology of cutting roof pressure relief can improve the coal recovery rate,reduce the mine excavation rate,optimize the handover procedure between working faces and increase the service life of the mine.Cut top pressure relief mainly along the working face to undertake pre-splitting kerf,improved the stress distribution of surrounding rock in coal face and goaf directly against the cutting seam face at the same time are more likely to be broken,the gravel is more,can better play a rock the hulking,effective support for basic roof,to reduce the impacts of pressure,make the left lane under the roof support in simple,The deformation is controllable and the production cost is reduced.But cut the top construction can lead to the transfer of stress field and stress field on the working face in the working face midpoint is asymmetric,the distribution of stress field of stope support selection and asymmetric work has a certain impact,so through collecting,sorting,analysis of data mine pressure regularity and the overburden of working face of the activities of the law,Based on this,it is of great significance to understand the adaptability of hydraulic support and working surface,improve the effective support rate of support and adopt reasonable support methods to ensure the safety of personnel and the normal operation of equipment.Taking the 62709 working face in North Qipan Area of Duerping Mine as the research background,this paper adopts the methods of field investigation,data collection,theoretical analysis,numerical simulation and engineering practice to study the ore pressure appearance law of the 62709 top-cutting pressure relief working face.The research results are as follows:(1)Collect relevant geological data of 62709 working face to understand the occurrence of roof and floor of coal seam;The physical and mechanical parameters of no.2 coal and rock mass were measured by drilling core,and the key positions of overlying strata on working face were analyzed.And design 62709 track lane,belt lane,working face layout and support.(2)FLAC3D simulation software is used to compare and analyze the vertical stress and vertical displacement of 62709 track lane and belt lane.It is concluded that the maximum value of vertical stress in the solid coal pillar on the left side of 62709 track lane is 53.9MPa,and the distance from the track lane is 1m.The maximum value of vertical stress in the solid coal pillar on the right side of 62709 transport lane is 65.7MPa,and the distance from the transport lane is 0.5m.The maximum roof displacement of 62709 track lane is 16.5mm,and that of 62709 belt lane is 19 mm.Then the influence of pressure relief by cutting top on the stress and displacement of the channel is analyzed.(3)According to the law of rock pressure of retaining roadway,it can be divided into four zones,and appropriate support methods should be adopted for different zones;Since the cutting roof construction is carried out in the track groove,the cutting top line runs through the whole direct roof and most of the basic roof,which will affect the movement of the overlying strata in the goaf.3DEC simulation software is used to analyze the fracture characteristics of the basic roof structure and the slice displacement of the model top.The fracture intervals of primary and periodic pressure of the basic roof and the fracture modes of the overlying strata in the goaf area are obtained.(4)According to the purpose and content of the mine pressure monitoring of the62709 working face,the working face is divided into upper,middle and lower test areas for monitoring,and four test points are selected in each test area to draw the load curve of each test point,and analyze and compare the difference of the initial pressure and periodical pressure falling distance of each test point in each test area;According to the 3d map of mine pressure of working face,the maximum load of hydraulic support in the upper test area is 52.5MPa,and its average value is30.93 MPa.The maximum load in the middle test area is 54.6MPa,and its average is36.92 MPa.The maximum load in the lower test area is 46.6MPa,and its average value is 26.53 MPa.The difference of ore pressure in each test area is analyzed and compared.(5)Combined with engineering practice,the adaptability evaluation of support and working face is carried out,and it is concluded that the resistance of hydraulic support is approximately normal distribution;The average working resistance is96.5% of the rated initial support force of the support,so the initial support force of the hydraulic support meets the support requirements of the roof;When the working face comes to pressure,the average working resistance of the support is 74.6% of the rated working resistance,so the hydraulic support can meet the periodic change law of the roof;The average dynamic load coefficient is 1.79,and the opening frequency of the safety valve is only 0.43%.Guzy5000/12/28 shield support has good adaptability to working face and can meet the safety production of working face. |
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