Study On Saturated Soandstone Fluid-solid Coupling Creep Property And Mechanism

With the progress of science and technology,more and more fossil energy substances are found and exploration,some of which can replace coal resources.At present,the coal resources still account for the main part of the consumable energy.With the increasing of the coal resources exploitation scale and depth,the frequency of mine rock mass system instability disasters shows an increased trend.The stress state of surrounding rock which even has moderate intensity is close to the rock strength limit under the condition of big and deep mining.Due to excavating and mining disturbance,surrounding rock is easy to produce large deformation,which causes the poor stability of roadway.Deep surrounding rock is in a complex environment of high temperature,high pore water pressure and high ground stress,the failure and deformation characteristics of which are obviously different from shallow rock,and the rock mass deformation is relevant to time.Taking mine roadway surrounding rock(sandstone)as the research object,using the MTS815.02 rock mechanics testing system,we do some research about fluid-solid coupling creep mechanism under the effect of pore water pressure by using research method of combining experimental research,theoretical analysis with numerical simulation.Based on the triaxial creep test results,we analyze the influence of pore water pressure on rock creep failure,and obtain mechanism about pore water pressure in the process of creep,which provides the basis for disaster prevention and control,supporting designment and reinforcement of roadway surrounding rock of deep engineering.(1)Carrying out saturated sandstone triaxial compression test,we discuss the main mechanical properties of saturated sandstone based on test results of fluid-solid coupling.We obtain the rock expansion initial stress through the analysis of triaxial compression volume strain of saturated sandstone,which provides the basis for creep test scheme designment.(2)Carrying out saturated sandstone fluid-solid coupling creep test,we analyze the effect of stress on creep deformation.And we can master the creep characteristics of saturated sandstone through deeply analysis of staged creep curves,isochronous stress-strain curves,creep rate and creep Poisson's ratio.At last,we can explain creep failure based on the sample characteristic parameters.(3)Using nonlinear Hook body instead of the Hook body on the basis of Kelvin model,we create a modified Kelvin model to describe the decay creep and steady creep;Besides,we can create a nonlinear visco-plastic body to describe the acceleration creep by using an unsteady non-Newton viscosity jugs and plastic body in parallel.And then,we create an improved Nishihara model and carry on the three-dimensional promotion.Using least square method and variable parameters recognition method to identify the test parameters,we can analyze the changing law of creep parameters with stress and time.And,we construct a three dimensional nonlinear variable parameters creep equation.Through Ansys finite element software,embedding custom creep equations,the creep test results are simulated,which further verified the correctness and rationality of creep model and the changing law of creep parameters over time.(4)Based on the effective stress theory,combining with creep deformation test results,we can analyze the influence of pore water pressure on rock creep failure,and then creep deformation and failure mechanism under the effect of pore water pressure is concluded,which can provide the basis for disaster prevention and control,supporting designment and reinforcement of roadway surrounding rock of deep engineering.