| As the coal resources are gradually mined from shallow surface to deep,the surrounding rock conditions are becoming more and more complex,the problems encountered are also increasing frequently,and the support of the roadway becomes increasingly difficult.The surrounding rock of roadway is generally supported by anchor bolt.Because of the poor lithology of minge,it is necessary to arrange prestressed anchor cable to reinforce and support the roadway.This paper mainly studies the stress distribution of anchor cables with different pre-tightening forces and different lengths in surrounding rock,the influence of anchor cables on the thickness of compressed arch and the distribution of displacement field when only anchor bolts are arranged.These are of guiding significance to the safe and reasonable mining of coal.In this paper,the additional stress field formed in the surrounding rock with different pre-tightening forces and the thickness of compressed arch before and after the addition of anchor cable are simulated by experiment and numerical simulation.In order to make the whole analysis process efficient,fast and representative,minge is selected for the study of coal lithology.The stress of protolith is 0Mpa.The roadway is a semi-circular arch with straight wall and its section shape is composed of semicircle and rectangle.The radius of upper half circle is 2600 mm,the rectangular length and width are 1600 mm and 5200 mm,respectively.The anchor bolt length,pre-tightening force and row interval are 2800 mm,80KN and 400mm×400mm,respectively.The length of anchor cables is 4000 mm,4500mm,5000 mm,6300mm and 7000 mm.The pre-tightening force selects 0KN,80 KN,160KN,240 KN and320KN,respectively.FLAC3 D software is used to simulate additional stress field distribution of anchor cables of the same length and different pre-tightening forces and of the same pretightening forces and different lengths in the surrounding rock.Tecplot software is used to slice the corresponding data to obtain the simulation data,and the corresponding curve change relationship diagram is drawn by Origin software.After comparison and analysis,the appropriate length and pre-tightening force of anchor cable are selected according to the actual demand to analyze the arch thickness of compressed arch when only anchor bolt is arranged and when the anchor cable is added.Finally,the displacement field formed when the anchor bolt is only arranged and after the anchor cable is added are simulated respectively,and the simulation dataare obtained by slice processing.The corresponding simulation analysis shows that:The length of and pre-tightening force of anchor cable will affect the additional stress distribution to a certain extent,and the pretightening force is more significant.When only 4 bolts(length L=2800mm,preload F=80KN,inter-row spacing a×b=400mm×400mm)are arranged in the tunnel gang respectively,the additional stress field can be superimposed into an arch,and the anchors are superimposed on the arch The thickness is about 160 mm.Through parameter optimization and economic and reasonable consideration at the same time,a reasonable anchor cable length L=4000mm and pretension F=240KN were selected.After adding the anchor cable,the thickness of the anchor arch was about 834 mm.Adding anchor cable to the roadway side can make the surrounding rock stable.The thickness of compressed arch increases obviously after adding anchor cable.When only prestressed anchors(length L=2800mm,pretension F=80KN,row spacing a×b=400mm×400mm)are arranged,the maximum displacement on the surface of the roadway side is about 650 mm,and the anchor cable(length L=4000mm,pre-tension F=240KN,row spacing a×b=1500mm×1500mm)The maximum displacement on the surface of the roadway rim is about 540 mm.The displacement of surrounding rock can be effectively controlled if it is supported using anchor bolt.In general,the addition of prestressed anchor cable has a influence on the thickness of compressed arch when only prestressed anchor bolt is arranged,and the relevant numerical simulation analysis in this paper can provide some reference significance for practical engineering.Figure 52 table 8 reference 62... |
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