| As the focus of national coal mining gradually shifts to the western region with better resource endowment and more resource reserves,the problems of deep burial,large section and high stress in western mines have become increasingly prominent.After entering the deep mining,the shortcomings of the current support system gradually appeared,and the deformation of the surrounding rock during the excavation period was unstable,and the excavation efficiency was inefficient,which restricted the safe and efficient production.Taking Haize Coal Mine 20102 Wind Alley as the engineering background,this thesis studies the deformation instability law of deep large-section coal alley by combining on-site research,theoretical analysis,numerical simulation and industrial test to solve the problem of large-scale deformation and excavation imbalance of surrounding rock in deep cross-section coal alley,clarifies the connotation of the linkage effect of the circle layer and the core of the topping cocontrol technology,and forms a single,low-density and high-efficiency thick-layer cross-anchoring support technology,and achieves good engineering practice application results.The main conclusions reached are as follows:(1)The buried depth of the 20102 return air lane of Haizai Coal Mine is 622.5m,the maximum horizontal stress and vertical stress measured on site are 16.87 MPa and14.92 MPa,respectively,the section area of the roadway exceeds 20m2,and the equivalent span of the roadway is large,and the roof plate is prone to flexural deformation.The current situation of poor coupling between the existing support mode and the corresponding qualitative conditions and poor maintenance and control effect of the roadway is analyzed,and the following conclusions are drawn:(1)the coal seam has a large burial depth,high stress,and complex native conditions of the surrounding rock of the roadway;(2)The coal seam is relatively soft,and the problems of collapse and hole plugging during the coal support period are frequent.(3)The support density is large,and the support efficiency of a single bolt is low;(4)The excavation speed is slow,the support system is disturbed by cutting for a long time,and the surrounding rock damage is large;(5)The foundation anchoring adopts rigid anchors,which are limited by the working height,the support thickness is not enough,and the top control ability is insufficient.(2)Study the discontinuous deformation characteristics of deep buried roadways.The excavation of the roadway leads to stress unloading of rock mass at different levels in the shallow part of the roof plate,and the stress unloading leads to deformation of the rock mass.The degree of stress attenuation and deformation of rock mass in different layers of the roof plate is different,resulting in the phenomenon of discontinuous deformation of rock mass.The degree of discontinuous deformation showed a trend of decreasing from the shallow to the deep part of the roof plate,until a continuous deformation zone with small deformation amount and stable rock formation appeared.With the increase of the buried depth of the roadway,the discontinuous deformation degree of the roof plate and its extended range showed an increasing trend.(3)The theoretical connotation of the circle-layer linkage effect is revealed.The high load-bearing characteristics of the anchor support of the thick anchor layer were clarified.Under the same roadway roof conditions,increasing the length of the bolt(thickness of the anchoring layer)can promote the anchorage end of the bolt to be anchored in the continuous deformation zone with small deep deformation and stable rock mass,and the deformation difference of the rock mass within the anchoring range of the anchor increases and the bolt load can rapidly increase the characteristics that limit the deformation of the shallow rock mass.When the length of the bolt increases to a certain range,the displacement difference of the rock mass within the anchorage range tends to be stable,and the working load also tends to be stable.(4)The mechanism of helping the top co-control was expounded,and the engineering cases were used for analysis.The core of roof co-control is to build a continuous beam support system for the roof,which greatly improves the stability of the roadway roof and equalizes the pressure of the roadway through continuous roof control under the support of continuous beam theory and efficient long anchoring technology.The pressure of the coal body in front of the roadway and on both sides of the roadway can be reduced in both directions,and then thick anchors are adopted to alleviate the deformation of the coal gang and inhibit the sheet gang.Collaborative support is the embodiment of the connotation of helping the roof co-control,and taking the Haize 20101 return wind lane as an example of the project,it has achieved a good roadway maintenance and control effect and released the excavation potential.(5)Industrial tests were carried out in Haijie 20102 Wind Alley,and good roadway maintenance and control effects were achieved.A thick layer cross-border anchoring support technology characterized by single,low density and high efficiency is proposed,and the thick anchor and thick support are proposed to realize the upgrading of coal lane support technology.The experimental results show that the bearing performance of the support system is effectively improved,the separation cracks of the roof plate are basically controlled in the shallow part of the roof plate,the progressive damage and failure of the roof plate are effectively controlled,the excavation speed exceeds 600 m,and the rapid excavation of the deep buried large-section coal alley is realized.This thesis has 75 figures,6 tables,and 80 references... |
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