Creep Behavior Test And Safety Project Analysis Of Argillaceous Sandstone With Different Soaking Time

Under complex stress conditions,rocks can exhibit elasticity,plasticity and viscous properties.At the same time,rocks also have time-related properties,which is the rheological properties of rocks.Rock rheology can be seen everywhere in engineering.It is an important cause of deformation and even destruction of rock underground engineering,slope and landslide.However,based on the diversity of rocks,the rheological properties of rocks will be affected by the properties of different rocks,and also by external conditions such as in-situ stress,water and other factors.It is necessary to consider these subjective and objective factors comprehensively in order to study the rheological properties of rocks more accurately,which leads to the incomplete theory of rock rheology in recent years.Based on the project of water conveyance tunnel in Lanzhou water source area as background,this paper carries out triaxial creep tests of argillaceous sandstone tunnel section under different soaking time.Through the test results,the creep curve characteristics,creep failure morphology,confining pressure effects on creep characteristics and creep characteristics of argillaceous sandstone are studied,and then the selection and inversion of creep model of argillaceous sandstone are studied.The fitting degree of the fitting curve and the test curve is analyzed,and the linear relationship between the same parameters of the creep model under different soaking time is obtained.The engineering calculation parameters are obtained by comparing the trial calculation results with the field measured data.The tunnel section is numerically simulated and analyzed by using the parameters,and its safety is studied and analyzed.The specific research contents of this paper include the following items:?1?Based on the water conveyance tunnel project of Lanzhou Water Source Area,a muddy sandstone section in the tunnel is selected to collect rock samples and make them into samples.Triaxial creep tests of muddy sandstone under different soaking time are carried out in the laboratory of Institute of Geotechnical Mechanics.Through triaxial creep tests in the laboratory,the creep curve law,failure pattern and the influence of confining pressure and water are studied and analyzed.It lays a foundation for further study on creep constitutive relationship of argillaceous sandstone.?2?In order to study the creep constitutive relationship of argillaceous sandstone after triaxial creep tests under different soaking time,we need to introduce creep constitutive model.After choosing the model,the model parameters are inverted,and the range of parameters is obtained by sensitivity analysis.Then the model curve is fitted based on uniform design method,and compared with the test curve,the fitting effect is compared,and the linear relationship between the same parameters of grade axial load under different soaking time is obtained.?3?Based on the previous work,the engineering calculation parameters are obtained by comparing the trial results with the actual field data,and the shaly sandstone tunnel is simulated by FLAC^3D.In ANSYS,the pre-processing model and mesh generation are carried out,and then the Burgers model in FLAC^3D is selected for numerical analysis.The deformation,maximum principal stress and minimum principal stress of lining are obtained to study its safety.