| The mining of coal resources in the shallow part of the Lianghuai mining area in Anhui and even the whole country has basically been completed,and the mining of coal has continued to deepen the earth.With the deepening of coal mining,the geological conditions of deep roadways become more and more complex and changeable,and fault fracture zones are prone to appear.The fault fracture zones have poor geological conditions and low bearing capacity of surrounding rocks,which seriously affects the safety and quality of roadway construction.Therefore,it is very important to properly support the fault fracture zone in the deep roadway.At present,pre-stressed anchor(cable)support has become an indispensable support method for deep roadway fault fracture zone support.Pre-stressed anchor(cable)compression arch can effectively prevent deformation and instability of surrounding rock.Therefore,it is of great significance to study the effective formation of pre-stressed anchor(cable)compression arch and the reasonable arrangement of supporting parameters in the support of deep roadway fault fracture zone.This paper takes the fault fracture zone of the circular roadway in the west wing of the Yuandian No.2 Mine of Huaibei mining area as the background to study the effective formation of the pre-stressed anchor(cable)compression arch in the coal and rock of the fault fracture zone and the reasonable support parameters.The method of combining experimental theory and numerical simulation is used to analyze the additional stress field in the surrounding rock under different bolt(cable)parameters at the edge of the fractured zone of the circular roadway.In order to make the analysis representative,the prestress of the bolts is 0KN,50 k N,70 k N,90 k N,the length of the bolts is 1500 mm,2000mm,2400 mm,2600mm,and the distance between the bolts is 0.4m,0.5m,0.6m.,0.8m;the anchor cable prestress is 80 KN,100KN,120 KN,the anchor cable length is 1000 mm,4000mm,5000 mm,6300mm,and the anchor cable spacing is 0.4m,0.5m,0.6m,0.8m;then from the additional stress From the analysis results of the analysis,the effective formation of the compression arch of the side of the circular roadway in the fracture zone of the fault and the support displacement under the original rock stress are combined to determine the reasonable prestressed bolt(cable)support parameters.Use the numerical simulation software FLAC3 D 5.0 to perform numerical simulation.After the numerical simulation results are obtained,use FLAC3 D 5.0 to obtain the specific data,and then use the drawing processing software Origin to sort these specific data and draw them into a graph to obtain the additional stress curve.Finally draw the following conclusions:(1)Under the action of prestressed bolts(cables),the distribution of additional stress in surrounding rock within a certain range from the surface of the roadway shows "fluctuation" changes,and then as the distance from the surface of the roadway increases,the additional stress decreases rapidly.The "fluctuation" variation range of the additional stress distribution of surrounding rock can be used as the compression arch thickness of the prestressed bolt.(2)The length of the anchor rod has a relatively obvious effect on the compression arch thickness of the prestressed anchor rod,but it has almost no effect on the additional stress within the range of the compression arch thickness.In the range of bolt length L=1500?2600mm,the compression arch thickness of surrounding rock is about d=850?1600mm.As the length of the bolt increases,the compression arch thickness increases almost proportionally.(3)The bolt row spacing and bolt pre-tightening force have no obvious influence on the thickness of the compression arch of the surrounding rock,but they have a significant influence on the magnitude and superposition of the additional stress of the compression arch.When the row spacing between bolts is reduced from a×b=600×600mm to a×b=400×400mm,the additional stress of the surrounding rock at the helper will be further effectively superimposed,and the magnitude of the additional stress will increase by about1.5 times.The anchor pretightening force F=50?90k N,with the increase of the anchor pretightening force,the additional stress of the surrounding rock within the compression arch range of the prestressed anchor increases proportionally.(4)The length of the anchor cable is increased to L>4000mm,which has little effect on the compression arch thickness and additional stress of the surrounding rock prestressed anchor.Arranging anchor cables at key parts of the roadway that are prone to "instability" can increase the additional stress of the surrounding rock by about 1.0 times,thereby significantly increasing the compression arch strength of the prestressed anchor.Finally,reasonable selection of prestressed anchor(cable)support parameters.See the text for details,which can be used as a reference for engineering practice.Figure [45] table [7] reference [66]... |
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