Rayleigh波作用下地下综合管廊动力响应三维数值分析

Three dimensional(3D) numerical analysis of dynamic response of underground utility tunnels to rayleigh wave effects

地下综合管廊由于埋深较浅,Rayleigh波能量对综合管廊的地震反应具有重要影响。建立非线性有限元三维动力数值模型,通过边界脉冲荷载生成Rayleigh波,研究Rayleigh波平行入射条件下综合管廊结构的加速度、位移和内力等响应特性,然后分别研究管廊断面尺寸、覆土厚度、Rayleigh波入射角和土体本构等因素对管廊结构动力响应特征的影响。研究结果表明:Rayleigh波平行入射作用下,综合管廊结构顶板受力表现为时而受拉以及时而受压,Rayleigh波传递过程对管廊结构受力产生不利影响;当Rayleigh波入射方向与管廊结构轴向夹角越接近90°,引起的动力响应相对越大;土体采用摩尔-库伦模型(MC模型)时,由于不能考虑材料滞回环属性对能量的耗散,相对于小应变硬化模型(HSS模型)模拟出的管廊结构内力和位移响应要大;管廊埋深越浅,结构位移响应幅值和内力响应幅度变化越大;不同截面管廊结构的纵向位移差别不大,竖向位移则随截面增大而减小,表明随着截面刚度的提高,抗变形能力增强;管廊结构内力峰值变化量随截面增大而减小,单仓结构在Rayleigh波作用下的内力响应最为显著。

As underground utility tunnels are usually buried at shallow depths, their seismic response is largely affected by the energy carried by Rayleigh waves. This study, by building a non-linear finite element （FE） three dimensional （3D） numerical model in which Rayleigh waves were generated by pulse loads at the boundary, attempted to investigate the response characteristics of utility tunnels, including acceleration, displacement and internal force, when Rayleigh waves arrived with strike-parallel incidence. Then, a host of influencing factors such as crosssection size of tunnels, thickness of covering soil, incidence of Rayleigh waves and constitutive of soil on the dynamic response characteristics of utility tunnels were explored. The research results show that under the effects of parallelly incident Rayleigh waves, the roof of tunnels are subjected to tension and pressure alternatively and the stress imposed on tunnels are negatively influenced by the propagation of Rayleigh waves; when the angle between the incidence direction of Rayleigh waves and the axial direction of tunnels is approaching to 90 degrees, there would be a more intense dynamic response ; the simulated internal force and displacement of utility tunnels are lar- ger in a Mohr-Coulomb （MC） model than in a hardening soil model with small strain stiffness （HSS）, since the MC model failed to take into account the dissipation of energy due to hysteresis loops ; the shallower the burial depth of tunnels, the larger the amplitude of displacement response and the larger the amplitude of variation on internal force response; cross-section size of tunnels exerts very little influence on the tunnels＇ longitudinal displacement, while vertical displacement decreases as cross-section size increases, which means deformation resistivity increases with the increase of cross-section rigidity ; the variation on peak value of internal force decreases with the increase of cross-section size, and the internal force response of single-cabin tunnels is the most significant to Rayleigh wave effects.