Analysis on Seismic Performance of Saturated Porous Elastic Full Space Composite Lining
At present,the studies of domestic and foreign scholars on the analytical solution of the lining dynamic response of tunnels under seismic wave disturbance are mostly on single-layer lining,while tunnels in actual working conditions generally include primary and secondary linings.Therefore,it is necessary to study the seismic performance of composite lined tunnels.Taking deeply buried composite lined tunnels as the study object,a higher-order strain gradient nonlocal poroelastic computational model considering size effect and nonuniformity structure effect is established to describe the specific physical properties of porous media materials and structures.The Biot theory is improved by introducing 2 length parameters,the nonlocal parameter and the scale factor.The analytical solution of the composite lining is obtained by adopting the wave function expansion method.Considering the boundary conditions of the deep-buried composite lined tunnel,the magnitude of the dynamic concentration factor around the composite lined tunnel is determined,and the effects of the size factor and non-local parameters on the magnitude of the dynamic stress concentration factor of the lining,as well as the effects of the inner and outer lining stiffness and thickness on the dynamic stress concentration factor(DSCF)of the inner and outer boundaries of the lining are analyzed at different incident P-wave frequencies.The result shows that at high frequency,the influence of non-local parameters and size factor on the DSCF inside the lining is larger.The non-local parameters have weakening influence on the DSCF inside the lining,and the size factor has enhancing influence on the DSCF inside the lining.At low frequency,the larger the stiffness of the outer lining is,the larger the DSCF inside the outer lining is,and the smaller the DSCF inside the lining is.It indicates that when the outer layer of the lining is not damaged,the inner lining is appropriate,and the material with smaller stiffness is favorable to the safety of tunnel lining.At low frequency,the larger the lining thickness is within the reasonable range,the smaller the DSCF is inside the lining.The analyzed result can provide reference for the design of tunnel composite lining.
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