Application Research Of High Constant Resistance Mechanical Single Prop In Retraction Channel Support

The support of retracting tunnel in mining face is one of the important contents in the research direction of roadway support.The retracting channel is basically located in the coal body.Due to the low strength of the coal body and the influence of mining,the surrounding rock is seriously deformed in the final mining stage.The cost of repair and maintenance is high,which seriously affects the moving speed of the mining face.In view of the specific engineering geological situation,it is an urgent problem to explore the reasonable and effective control technology of the retracting channel of the mining face.Based on this,this paper takes the support of the retreating channel of the 1070 level 2 panel working area of Tashan Coal Mine as the engineering background,and uses the theoretical analysis,numerical calculation,laboratory test and field test to systematically analyze the working principle of the high constant resistance mechanical single prop and retreat channel deformation failure mechanism.On the basis of the deformation and failure mechanism of the retracement channel,the control technology of surrounding rock before and after the retracement channel is proposed.The main conclusions of the thesis are as follows:(1)Through the actual monitoring of the mine pressure of 8216 mining face in the retracting channel,the original support form,in-situ stress test and surrounding rock deformation and failure characteristics of the retracting channel were studied,and it was concluded that the surrounding rock presented large deformation and asymmetric failure characteristics before and after the retracting channel was connected.Under the original support scheme,the support resistance could not meet the requirements.(2)The calculation model of high constant resistance mechanical single pillar support resistance is established,and the balance equation of the pillar and the calculation formula of the stable bearing capacity are derived.The laboratory test of strut support resistance analysis was carried out,and the influence rules ofsteel ball diameter,bevel angle of cylinder,number of steel ball layerssupport resistance was analyzed.(3)The influence range of the retracting channel by the mining action is obtained;FLAC3D software was used to simulate and analyze the influence of the distance between single pillar and side wall,support strength of pillar and lateral pressure coefficient on the distribution of surrounding rock stress,displacement and plastic zone of the retracting channel.(4)The coupling support scheme of "mechanical single prop-anchor rod-anchor rope-metal mesh-steel belt" was put forward before the opening of the retracting channel,and the industrial test was carried out.The results show that compared with the original support scheme,the deformation of roof,floor and two sides is effectively reduced.By giving full play to the high supporting resistance performance of the mechanical single pillar,the stability of the surrounding rock of the retracting channel can be significantly improved.(5)the support technology of 8216 mining face stoppage and the support scheme during the withdrawal of mining face equipment are proposed.Through field observation,in the process of equipment withdrawal at the mining face,the support of single pillar has a better effect of top cutting and pressure relief than that of wooden crib,which reduces the occurrence of hydraulic support crushing disaster,shortens the time of equipment withdrawal,and ultimately saves about 820 thousand yuan of support cost.