分层土-隧道相互作用体系地震响应分析

Seismic response of layered soil-tunnel interaction system

摘要:

为研究地震作用下非均质场地各个土层放大效应以及分层土-隧道的地震响应,以大连某实际工程为背景,基于地震作用下隧道结构动力响应的理论,采用收敛约束法,通过ABAQUS构建分层土-隧道三维有限元模型,并结合振动台试验,验证模拟的准确性;将自由场与有隧道场地进行对比,并结合加速度和傅里叶曲线对模拟数据进行分析。结果表明:(1)土体性质和激励大小对地震波的传递有影响,随着场地由浅到深逐渐增加,峰值加速度逐渐放大,不同分层介质的主要频率和频谱形状发生明显变化；(2)隧道会放大远场的加速度响应,略微降低近场的动力响应；(3)软弱夹层的存在对地震动的放大作用也有明显影响,不同分层介质的不同特性导致土层刚度不同,从而影响地震作用下层状土-隧道的动力相互作用。

Abstract:

This study used Dalian Metro as background to study the amplification effect of each soil layer in the heterogeneous site and the seismic response of a layered soil-tunnel system under seismic action. Based on the theory of dynamic response of tunnel structure under seismic action, a three-dimensional finite element model of the layered soil-tunnel was constructed with ABAQUS and a convergence constraint method. The simulation accuracy was verified by a shaking table test. Then, the free field was contrasted with the tunnel site, and the simulation data were analyzed in combination with the acceleration and Fourier curves. Results show that (1) the soil properties and excitation magnitude affect the transmission of seismic waves. As the site gradually increases from shallow to deep, the peak acceleration gradually increases, and the main frequencies and spectrum shapes of different layered media change obviously. (2) The tunnel amplifies the acceleration response in the far field and slightly reduces the dynamic response in the near field. (3) The weak interlayer has an evident influence on the amplification effect of earthquakes. The characteristics of different layered media lead to different soil stiffness, further influencing the dynamic interactions of the layered soil-tunnel during earthquakes.