Study On The Layout And Stability Control Technology Of Bottom Extraction Roadway In Licun Coal Mine

The current situation of high gas or coal and gas outburst coal seam driving speed is less than the recovery speed,which makes the mine mining relationship tense.A large number of engineering practices show that there are two key points restricting the excavation speed:(1)the support speed is slow and the excavation branch system does not match;(2)the empty top distance is small,the excavation branch cycle step is small,the auxiliary time is long,and the excavation efficiency is low.Therefore,on the premise of ensuring construction safety,it is of great significance to determine the reasonable maximum ceiling distance,study the stability control mechanism of the head-head roof,reasonable support parameters and construction procedures,which are of great significance to improve the tunneling efficiency and achieve high coal production and high efficiency.Based on the engineering background of the 3301 air-inlet bottom-drawing roadway in Licun Coal Mine,this thesis comprehensively adopts research methods such as on-site investigation,laboratory test,theoretical analysis,numerical calculation and field test,etc.The mechanical structure of the roof in the roof area and the main influencing factors and influence laws of its stability reveal the deformation and failure laws of the roof in the empty roof area.The reasonable layout scheme of the bottom-drawing roadway was determined through research,and the high-efficiency branch excavation step-by-step support control technology was proposed,which was successfully applied,and the following main achievements were obtained:(1)According to the theoretical calculation of the slip line field of the floor,the failure depth of the floor of the 3301 working face is 9.73 m.By constructing the FLAC3 D numerical model,the vertical stress distribution characteristics of the coal seam floor and the deformation and failure law of the surrounding rock of the bottom-drawing roadway under the action of dynamic pressure are analyzed.A working face is 15 m along the groove.(2)The thin-plate mechanical model of the roof in the head-end void area is established,and the deflection,stress and the expression of the limit head-head distance of the thin-plate model are deduced.Based on the roof tensile failure criterion,the theoretical limit space of the head-head is determined.The top distance is 2.97 m.The sensitivity that affects the ultimate void-roof distance,from large to small,is the thickness of the rock mass that occurs in the shallow roof of the void-roof area,the overlying load of the roof in the void-roof area,and the strength of the roadway roof.(3)The influence law of the empty roof distance,cyclic step distance and support strength on the roof stability of the empty roof area is analyzed: the head-on empty head distance has a significant influence on the stability of the surrounding rock of the roadway in the empty roof area.After more than 4.0m,the vertical stress of the roof and the side of the empty roof area will decrease and transfer to the deep part,which will increase the deformation of the surrounding rock of the roadway.Linear increase,the increase of the subsidence of the roof at the rear of the empty roof area increases with the increase of the cycle step;increasing the support strength can effectively improve the bearing state of the roof,and at the same time has a significant control effect on the roof in the support area.(4)Propose the high-efficiency excavation branch support control technology of bolt timely support and anchor cable lag support to increase the driving speed,and determine the anchor cable lag support distance of 10 m and the row spacing between bolts to be 900× 1400 mm,the anchor cable arrangement is 2-1-2 and other key support parameters.(5)It is determined that the 3301 air-inlet and bottom-drawing roadway of Licun Coal Mine adopts a high-efficiency excavation plan with a large circulation step distance of 2.8m and an anchor cable lag of 10m;the on-site mine pressure observation and the actual measurement of the excavation efficiency show that the bolt and anchor cable effectively cooperate to carry and guarantee The roadway is safe and stable,and the driving speed is increased by more than 40%.In this thesis,there are 56 figures,7 tables,and 86 references.