| With the development of deep coal mining,the frequency and intensity of rock burst accidents are getting higher and higher.According to statistics,a large number of coal mine rock burst accidents occur in the roadway,mainly because under the high static stress,dynamic stress or static and static stress superposition,the roadway surrounding rock bears the stress exceeding its own strength limit,and a large amount of accumulated elastic energy is suddenly and dramatically released,resulting in the roadway surrounding rock thrown out and support equipment damage.Therefore,the previous researches on roadway support have carried out a lot,but they usually relieve the pressure of the surrounding rock of the roadway to reduce its stress concentration degree,or increase the external protection facilities to strengthen the support,so as to improve the anti-shock support ability of the roadway.The above support or pressure relief methods all belong to passive protection,and the performance of roadway surrounding rock itself is not considered to improve the anti-rushing ability of roadway.Therefore,based on the mechanical action characteristics of the impact dynamic wave on the surrounding rock of the roadway,this paper innovatively put forward the roadway in situ modified anti-impact support scheme.Using theoretical analysis,numerical simulation,laboratory experiment and field experiment,such as research methods,analyzes the impact on power under the action of P wave,the mechanical properties of support by the modification bumper and the supporting mechanism of it is concluded that the modification of roadway supporting effect optimization scheme,impingement and physical analog simulation experiment and field experiment,verify the impingement supporting effect.The main research results of this paper are as follows:(1)The mechanical mechanism of impact dynamic load on roadway surrounding rock is deduced theoretically,and it is pointed out that the stress effect of impact dynamic load on roadway surrounding rock is affected by the elastic modulus of roadway surrounding rock itself and the thickness of supporting surrounding rock.A method of in-situ modification of roadway surrounding rock into grouting reinforcement area and fracture weakening area is put forward.Based on Fourier-Bessel function expansion method,the mechanical action characteristics of in-situ modification of roadway anti-punching support under the impact of P wave are deduced.(2)Through numerical simulation and orthogonal experimental design,the influence of the thickness of surrounding rock in the reinforcement area,the increase degree of the elastic modulus of surrounding rock in the reinforcement area,the thickness of surrounding rock in the weakening area and the decrease degree of the elastic modulus of surrounding rock in the weakening area on the effect of insitu modification of roadway anti-punching support is studied.It is pointed out that the optimization scheme of anti-impact effect of roadway in-situ modification is as follows:the optimal thickness of roadway surrounding rock is 4m in the weakened modification area,and the elastic modulus of surrounding rock in the weakened modification area is reduced to 90%of the original rock;the thickness of roadway surrounding rock reinforcement modification area is 5m,and the elastic modulus of surrounding rock in the strengthened modification area is increased to 10%of the original rock.(3)Through similar simulation physical experiment,the anti-impact support effect of roadway in situ modified anti-impact support optimization scheme is verified.Compared with the unmodified coal and rock mass,the peak dynamic stress,peak acceleration and peak velocity of surrounding rock particles in the weakened modified area and the reinforced modified area of the in situ modified roadway are reduced to a greater extent,and the vertical displacement is reduced.After the in-situ modification of roadway surrounding rock,the surrounding rock in the weakened area has a significant absorption and dissipation effect on the propagation of dynamic wave,and the surrounding rock in the strengthened area plays a supportive and protective role on the roadway,which reduces the possibility of rock burst under the action of large impact dynamic load,and ensures the stability and integrity of roadway surrounding rock itself.(4)Through theory,numerical experiment and field condition analysis,the sequence of roadway surrounding rock weakening and strengthening and the field application basis are studied.The order of surrounding rock weakening and then strengthening was determined.The order of surrounding rock weakening was as follows:surrounding rock of the roof and floor of the roadway-surrounding rock of the upper and lower corners of the roadway-surrounding rock of the two sides of the roadway;The sequence of roadway surrounding rock reinforcement is as follows:surrounding rock of two sides of roadway-surrounding rock of upper and lower corners of roadway-surrounding rock of roof and floor of roadway.The directional pre-split blasting technology and grouting reinforcement technology are adopted to improve the elastic modulus of surrounding rock in the weakened modified area of roadway.(5)Through field experimental study,the feasibility and correctness of the optimization scheme of roadway in situ modified anti-impact support are verified.The research results show that:in the roadway with in situ modified anti-impact support scheme,the surrounding rock of shallow reinforced modified area and deep weakened modified area,compared with the unmodified roadway supporting surrounding rock and original rock,the stress and stress concentration coefficient are significantly reduced.The subsidence of roadway surrounding rock is effectively controlled after the modification of roadway surrounding rock is weakened and strengthened.The research results are beneficial to the surrounding rock support of roadway,and can provide new supporting theories and technical ideas for the dangerous impact roadway,prevent and control the rock burst accident,and ensure the safety production of enterprises.There are 102 figures,12 tables and 203 references in this paper. |
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