黏弹性饱和土中隧道在爆炸荷载作用下的动力响应

为了给隧道的抗爆防护设计提供理论依据,采用解析法研究了爆炸荷载作用下黏弹性饱和土体中圆形隧道的动力响应问题.假定爆炸发生在圆形隧道中心处,爆炸荷载采用峰值递减的三段突加三角形荷载,应用Biot波动方程模拟饱和土体,将土骨架视为Kelvin Voigt饱和土体,衬砌运动方程基于Flügge壳体理论,通过引入势函数,利用Laplace变换及数值逆变换,得到爆炸荷载作用下土体响应的时域计算结果,给出了在不同土体渗透性参数b*时的黏弹性饱和土中位移、应力的时程曲线,并与单相介质进行了对比；讨论了黏滞阻尼系数η对黏弹性饱和土中位移和应力响应的影响.数值分析结果表明：在爆炸荷载作用下,b*越大,位移和应力幅值振荡越显著,黏弹性饱和土中应力和位移响应幅值小于单相介质；在黏弹性饱和土中,η值越大,波衰减越快,位移和应力响应峰值越小.

Dynamic response of tunnel in viscoelastic saturated soil subjected to blast loads

The dynamic response of a circular tunnel in the viscoelastic poroelastic soil was investigated using an analytical method to provide theoretical basis for anti blast protection design of tunnel. Assuming that the blast occured in the center of the circular tunnel, a model was established using decrease three-stage triangle loads. Biots theory was used to describe saturated soil and Kelvin-Voigt model was used for soil skeleton. The motions of the liner were considered specially based on Flügge theory. By introducing potential functions, numerical results were obtained in time-domain by using the Laplace transforms and inversion of Laplace transforms. The curves of displacement and hoop stress with time for different b*, which denotes the permeability of the soil, on the interface between the liner and soil were presented, and compared with those of the single-phase medium. The influences of viscous damping coefficient η on the displacement and stress response were emphatically analyzed in the viscoelastic saturated soil. The results show that the amplituds of displacement and hoop stress increase with the increasing parameter b*. The amplitudes of displacement and stress in the viscoelastic saturated soil are smaller than that in the viscoelastic medium. With the increasing of η, the amplitude of the wave attenuates fast, whereas the maximum the displacement and stress response get smaller.