| With the depletion of shallow resources and the rapid growth of energy demand,the depth of roadway mining is increasing,In the deep engineering with high ground stress and large mining disturbance,the surrounding rock of roadway is prone to deformation and failure.The stability of roadway support structure is the premise of coal mine safety production.In order to maintain the stability of roadway,shotcrete is mostly used for support;however,the toughness of ordinary shotcrete is poor,which is prone to brittle failure and affects the safety of construction.In this paper,the mechanical properties of polymer composite fiber sprayed concrete are tested on the basis of "fiber spacing theory" and "composite theory".In order to better guide the application of field engineering,the test blocks are made by the mix ratio of coarse and fine aggregate and sprayed concrete.the basic mechanical properties of polymer composite fiber sprayed concrete were studied by orthogonal test and single factor variable test,and the optimum amount of admixture was selected.The toughening and crack inhibition mechanism of fiber and polymer emulsion are discussed and analyzed by means of electron microscope scanning(SEM)and CT scanning technology,and the simulation and comparative analysis of ordinary shotcrete support and basalt fiber reinforced polymer modified shotcrete(Basalt Fiber Reinforced Polymer Modified Shotcrete,BFRPMS)support are carried out by using FLAC3 D numerical simulation software.Finally,taking the numerical simulation as a reference,the optimal mix ratio is selected for field industrial test.The main conclusions are as follows:(1)The range analysis of orthogonal test shows that the toughness of BFR(P)ms increases first and then decreases with the increase of polymer content and fiber volume content.The optimum ratio is: polymer dosage is 3% of cement weight,fiber volume dosage is 0.3% of total concrete volume,water cement ratio is 0.4,water reducer dosage is 4 ‰ of cement weight.(2)The results of single factor test show that when only the volume content of basalt fiber(BF)is changed and other variables remain unchanged,the flexural compression ratio of BFRPMS first increases and then decreases with the increase of BF content,and the optimal volume content of BF is 0.2%.(3)Through the combination of CT scanning technology,digital image processing technology(DIP)and SEM microscopic scanning,the relationship between BF distribution and BFRPMS mechanical behavior response is explored,and the microstructure and macro performance response mechanism of BFRPMS is established.Digital image processing technology shows that the difference of mechanical properties of BFRPMS with different fiber volume content is mainly related to fiber content and fiber distribution,and to a lesser extent related to their contact rate,and SEM shows that a layer of polymer film is attached to the fiber surface,and the synergistic effect of fiber and polymer can give full play to its strengthening and toughening effect.Fiber orientation,distribution,contact point and polymer film formation affect the basic mechanical properties of BFRPMS.(4)FLAC3D software is used to simulate and analyze the BFRPMS support and ordinary shotcrete support under the optimal ratio.The range of plastic zone,the stress and displacement of surrounding rock,and the stress and displacement of shotcrete layer are compared.The numerical simulation shows that the plastic zone,the stress and displacement of surrounding rock,and the stress and displacement of shotcrete layer are reduced by using BFRPMS,which is better than that of ordinary shotcrete.(5)Based on the results of FLAC3 D numerical simulation,BFRPMS with the best mix proportion was used to carry out field industrial test.The convergence data of roadway was monitored and analyzed to verify the actual support effect of BFRPMS.The test results show that the rebound rate of BFRPMS support is significantly reduced,the convergence of two sides is significantly lower than that of ordinary shotcrete,the surface is smooth,although there is deformation,there is no cracking.There are 67 pictures,18 tables and 76 references. |
