| Deep surrounding rock is mostly of heterogeneous characteristics of joint density and fracture development,and is mostly affected by the long-term stress effect of high ground stress,high permeability water pressure and construction disturbance.Soft rock under multiple factors is prone to damage and large deformation,which leads to the deformation instability of the whole project surrounding rock and failure of supporting structure.Therefore,the failure law of deep fracture soft rock and the creep characteristics of the confining pressure relief process of the fractured soft rock under the coupling action of high stress field and seepage field are studied.It is of great significance to guide the support design,disaster prevention and treatment of soft rock geological roadway engineering under the condition of rich water,broken surrounding rock and fracture development in deep area,as well as high efficiency and safety construction.With the support of the National Natural Science Fund(51774166),taking the project of water rich soft rock roadway in fault fracture zone of hongqingliang coal mine in Inner Mongolia as the object,the field investigation,indoor test,similar material model test,uniaxial compression test of different moisture content of prefabricated fracture samples,triaxial compression test with high confining pressure,creep test of different initial osmotic pressure and confining pressure are adopted The theoretical analysis,numerical calculation and field monitoring research methods have achieved the following research results:(1)The basic physical and mechanical parameters,chemical composition and structural characteristics of argillaceous siltstone are determined by laboratory test.The similar material preparation scheme close to the original rock is determined by similar material model test,and a prefabricated fracture sample preparation method suitable for water stability is designed,and then the control mechanism of integrity index calculation parameters is deduced.(2)The compression tests of siltstone with different integrity levels were carried out to study the deformation characteristics and peak stress attenuation law of prefabricated fractured samples with different water content under unconfined uniaxial compression,the evolution law of apparent strain field during loading,and the variation law of cumulative acoustic emission energy and ringing times with the integrity index and water content of fractured samples;The variation of compressive strength,elastic modulus,Poisson’s ratio,cohesion and internal friction angle with integrity index and confining pressure were obtained.(3)The unloading confining pressure creep tests of pre cracked siltstone like specimens under different initial osmotic pressure were carried out,and the correlation laws of instantaneous strain,creep deformation and creep rate under various conditions were analyzed.According to the test results,a nonlinear viscoplastic body nvpb is connected in series on the basis of Nishihara model,and the seepage rheological coupling model HKN model of pressure relief fractured siltstone is established.(4)The finite element software MIDAS / GTS is used to embed HKN creep model to carry out numerical calculation model of soft rock roadway crossing fault fracture zone in hongqingliang coal mine.Taking the intersection section of roadway and fault as the research focus,the deformation characteristics are analyzed.The numerical simulation results are compared with the monitoring results of on-site fracture zone monitoring station,and the reasonable support scheme of combined support crossing fault fracture zone is determined. |
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