Study On Rheological Properties Of Fully Weathered Argillaceous Siltstone And Tunnel Deformation Control Technology

Rheology is the most common phenomenon in geotechnical engineering.Under the influence of rheology,the internal stress and strain of surrounding rock changes with time,which has an impact on its stability and the internal support structure of tunnel.In the construction of soft rock tunnel,especially in the early stage of excavation,the rheological effect of fully weathered rock mass is strong,which brings challenges to construction.Based on the actual engineering tunnel project,the rheological characteristics of fully weathered argillaceous siltstone are studied by means of theoretical analysis,laboratory test,data fitting and numerical model,and the "diseases" caused by the weak foundation of the tunnel are analyzed.The main work of this paper is as follows:(1)Sampling and uniaxial compression rheological test of tunnel passing through fully weathered argillaceous siltstone section.The variation of axial strain with time of silty mudstone under different stress levels is studied.Based on this,the rheological constitutive model which is most suitable for describing silty mudstone is obtained by fitting and comparing test data with different constitutive models.(2)Based on the above rheological constitutive model,the relevant parameters of rock mass are fitted by Prony series,which provides a basis for the next finite element analysis of tunnel rheology.(3)Based on ABAQUS software and rock rheological constitutive model,Prony series fitting method is used to excavate the tunnel and carry out two-dimensional numerical simulation.By comparing the measured data,the deformation and stress changes of tunnel under the influence of rheological aging of surrounding rock are analyzed.(4)In view of the tunnel's "disease" in the weak foundation crossing the whole weathered argillaceous siltstone section,the reinforcement scheme is explored,and the effectiveness of different reinforcement conditions for the treatment of "disease" is explored.Through ABAQUS three-dimensional model,the necessity of reinforcement scheme is discussed.Through ABAQUS numerical analysis,the reinforcement scheme is optimized in order to select reasonable,effective and resource-saving reinforcement conditions for disease control.