| With the extension of coal mining to the deep,the grouting consolidation body of deep fractured soft rock will gradually become rheological and unstable under long-term load,which will endanger the safety and stability of the grouting reinforcement project.Since the creep characteristics and long-term strength of grouting and consolidation body are the key indexes to evaluate the grouting reinforcement effect and long-term stability of fractured rock mass,it is of great significance to study the creep characteristics of grouting and consolidation body of fractured soft rock.In this paper,based on shaanxi province natural science foundation research project "deep broken soft rock creep mechanical properties and the application of the grouting concretion body research",laboratory test and theoretical analysis,numerical simulation,the method of combining the full red sandstone and grouting concretion body for the synchronization of uniaxial compression creep test,VIC3D test and acoustic emission test,The creep characteristics and failure characteristics of grouting consolidated body in uniaxial and triaxial compression creep tests were investigated.Based on the test results,the creep constitutive model was determined and the parameters were identified,and the creep numerical simulation of grouting consolidation body in the surrounding rock of fractured roadway was carried out.The main research contents and conclusions of this paper are as follows:(1)The uniaxial compressive strength,triaxial compressive strength,elastic modulus and other mechanical parameters of the samples were obtained through conventional compressive strength tests on the intact red sandstone and the grouted consolidated body.(2)The grouting consolidated body of fractured red sandstone has experienced the stages of decay creep,stable creep and accelerated creep in the uniaxial compression creep test.Under the same stress level,the creep rate of grouting consolidated body is larger and the constant creep time is shorter.The long-term strength of the grouting consolidated body was obtained by analyzing the isochronous stress-strain curve.In the accelerated creep stage,the number of acoustic emission e vents of grouted consolidated body is greater than that of intact red sandstone,and creep and re-failure occur at lower stress levels.(3)Compared with the intact red sandstone,the creep time of grouting consolidation body of fractured red sandstone under triaxial compressive creep is shorter.Under the same load series,the axial creep value and creep rate of the grouting consolidated body are larger and the constant creep time is shorter.With the increase of confining pressure,the axial total creep value of the grouting consolidated body specimen increases continuously.The long-term strength of grouting consolidation body under different confining pressures is about 85%of the instantaneous strength of the sample.(4)Based on the creep test results of uniaxial and triaxial compression,the creep curves of the intact red sandstone and the grouting consolidated body were identified by the generalized Kelvin model,the Nishihara model and the Burgers model.The results show that the Burgers model can better describe the linear creep characteristics of the samples.Using the nonlinear creep constitutive model,the nonlinear creep stage of the sample is fitted and the model parameters are identified,and the fitting effect is good.(5)Based on the creep constitutive model and creep parameters selected from the test results,a numerical simulation study on the creep of grouting consolidated body was carried out in COMSOL Multiphysics coupling software,combined with the same physical and mechanical parameters of the laboratory creep test,and the correctness of the creep constitutive model was verified by comparison.On this basis,the creep numerical model of grouting consolidation body in deep fractured roadway was established and the creep deformation and failure characteristics of surrounding rock were obtained. |
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