Roof Caving Mechanism And Control Technology Research On Roadway Under The Extremely Thick Coal Seam

Roadway roofing control problems has always been the research hotspot and difficulty point in the field of roadway support.Roofing accidents have high concealment,suddenness and high risks,which brings great mental stress,psychological fear and property damage.The plastic deformation of the roof roadway is an important reason for the occurrence of roofing.It is necessary to grasp the distribution law of the surrounding rock roadway.The environmental characteristics of the stress field of the surrounding rock are generally non uniform.The plastic deformation of the surrounding rock is bound to appear different from the uniform stress field characteristics.Therefore,it is one of the key problems to be solved urgently in the study of the mechanism of roadway roofing under non uniform stress field and the practical theory and method to solve the problem of roadway roofing.In this paper,the theoretical formula of the plastic zone distribution of the surrounding rock under inhomogeneous stress field is deduced.The influence factors of the plastic zone of the surrounding rock of the roadway under the uneven stress field are analyzed.The excavation depth of the roadway,the excavation radius of the roadway,And the factors such as the coercivity of the surrounding rock and the angle of the inner friction are related to the depth of the plastic zone of the surrounding rock.It is found that the excavation roadway has a petal plastic zone under the influence of the uneven stress,and reveals the roofing mechanism,The roof contains a weak rock layer and the petal plastic zone penetrates the lower hard rock formation in the weak rock formation,accompanied by a huge expansion pressure and strong deformation,the deformation of the surrounding rock damage in the existing technical conditions is almost given,So that the lower hard rock is sustained,huge "squeeze" load,resulting in the occurrence of fracture damage,when the weak rock area of the butterfly plastic zone formed deformation to a certain extent,the lower hard rock layer is completely lost Stable collapse,At this time can no longer bear the roof to destroy the weight of the rock,the roadway will take the roof.Therefore,the plastic damage and its deformation of the surrounding rock under the influence of the uneven stress under the large deformation mining roadway are almost given under the existing support condition,and it should be used to adapt to the large deformation of the surrounding rock,High working resistance,with sufficient anchorage range of supporting materials to curb the plastic area of the malignant expansion of the surrounding rock to ensure the stability of the plastic zone surrounding rock,and thus eliminate the risk of caving,forming a long anchor to the main means of support.Based on the 8512 working face of Chenjiagou Coal Mine,the flac3 D numerical simulation software is used to simulate the distribution of the plastic failure zone,the vertical and horizontal of the mining roadway during the excavation period,10 m from the working face of the mining face and 0m from the working face Stress distribution,displacement distribution in the vertical direction,distribution of the maximum and minimum principal stresses,and the distribution of the plastic zone around the surrounding rock mass in the surrounding area of the working face,so as to understand the development and expansion of the joint fissures of the large deformation mining roadway Taking the 8512 working face as the engineering example,the observation station monitoring the roadway in the case of ordinary support and the use of extended bolt support under the situation of the top and bottom of the roadway near the floor and the two sets of close to the amount,to determine the use of extended anchor Under the support of the roadway,for such large deformation of mining roadway roofing mechanism and control of valuable advice.