Stress concentration near bore-hold in clayey viscoelastic rocks

To predict long-term durability parameters of such complex and potentially dangerous structures as, for example, the dams, geological disposal of nuclear waste etc., a new enhanced mathematical model of clayey rocks behavior is suggested. With the aim to generalize known computational methods of elastic geotechnical analysis to the time-dependent problems the behavior of viscoelastic argillites is considered. The microstructure of argillites is supposed to be known in terms of chemical constituents, size and volume concentration of inclusions. Clayey rock is considered as heterogeneous materials composed of clay matrix, quartz, calcite, and clay minerals. The influence of mineral compositions on rheology parameters is evaluated. Constitutive model for the time-dependent behavior can be applicable under complex 3D load conditions. The computer model of time-dependent behavior of nonhomogeneous argillites is constructed, and concentration near elastic inclusions and on the surface of bore-hold in clayey rock matrix is calculated. The viscoelastic solution in the time domain is determined from the solution in the Laplace-Carson domain through performing the computational inverse transform. As an example, the problem of determination of creep deformation and stress relaxation near bore-hold boundary in argillite settlement is analyzed with finite element methods. Some evaluation of durability parameters is done.