饱和多孔弹性深埋复合式衬砌抗震性能分析

Analysis on Seismic Performance of Saturated Porous Elastic Full Space Composite Lining

目前国内外学者针对地震波扰动下隧道的衬砌动力响应解析解的研究多为单层衬砌,而实际工况中隧道一般包括初衬和二次衬砌。因此,研究复合式衬砌隧道的抗震性至关重要。以深埋复合式衬砌隧道为研究对象,建立了考虑尺寸效应和非均匀性结构效应的高阶应变梯度非局部孔隙弹性计算模型,用以描述多孔介质材料和结构的具体物理特性。通过引入2个长度参数、非局部参数及尺度因子来改进Biot理论。采用波函数展开法得到了复合式衬砌的解析解。考虑深埋复合式衬砌隧道的边界条件,确定复合式衬砌隧道周围的动力集中因子大小,分析了不同入射P波频率下,尺寸因子和非局部参数对衬砌动应力集中因子大小的影响,以及内外衬砌刚度和厚度对衬砌内外边界动应力集中因子(DSCF)值的影响。结果表明:高频下,非局部参数和尺寸因子对衬砌内DSCF值的影响较大,并且非局部参数对衬砌内DSCF值有削弱的影响,尺寸因子对衬砌内DSCF值有增强的影响;低频下外衬砌刚度越大,外衬砌内DSCF值越大,内衬砌内DSCF值越小,这说明在外层衬砌不被破坏的情况下,内层衬砌适当选择刚度小一点的材料有利于隧道衬砌的安全;低频下,衬砌厚度在合理范围内越大,衬砌内DSCF值越小。解析结果可为隧道复合衬砌设计提供参考。

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.