土-结构动力作用体系混合试验研究进展与探讨

土-结构相互作用机制的研究通常需要借助试验方法来检验相关分析理论和模拟方法的合理性。混合试验是一种结合物理试验与数值模拟各自优势的试验方法,近年来发展迅速并逐渐向应用研究拓展,而土-结构作用体系是混合试验的一个重要应用领域。首先根据不同子结构对象对试验进行分类,分别归纳总结土体数值域-结构试验域、土体试验域-结构数值域、地层特性混合试验这3类土-结构作用体系混合试验的研究进展。从多跨桥梁结构、浅埋基础框架结构等传统土-结构作用体系,到液化场地桩基、海洋自升式平台、隧道-桩基-地上结构等复杂土-结构作用体系,混合试验为不同类型的土-结构动力作用体系的相互作用机制均提供了有效探究手段。笔者团队在强震作用下地下结构动力混合试验模拟方面的研究工作包括:在OpenSees-OpenFresco平台构建地下结构混合试验框架,以大开车站为例对试验框架进行验证,并对不同加载边界条件下的混合试验精度进行评价。研究结果表明:虚拟混合试验结果与纯数值模拟结果吻合良好;反弯点加载边界与完备加载边界的试验精度在小震工况(0.12g)下十分接近,但在大震工况下(0.58g)偏差较大。最后探讨了目前土-结构作用体系混合试验研究存在的共性问题,以期为今后混合试验的研究重点指明发展方向。

Review and Discussion on Recent Progress of Hybrid Simulation for Soil-structure Dynamic Interaction System

The problem of soil-structure interaction often requires an experimental approach to validate the reasonability of corresponding theories. As a combination of physical tests and numerical simulations, hybrid simulation demonstrates the merits of both numerical and physical methods. Recently, there have been many developments and extensions to practical applications in several fields. The soil-structure interaction system is one of the major application fields in hybrid simulation. With consideration of different research purposes, this paper summarizes the development of hybrid simulation in the field of soil-structure interaction and divides the hybrid simulation into three types:the soil treated as a numerical subdomain and the structure as an experimental subdomain; the soil treated as an experimental subdomain and the structure as a numerical subdomain; and the hybrid simulation of stratigraphic characteristics. Hybrid simulation has provided an effective tool for exploring the interaction mechanism of soil-structure dynamic systems, including traditional soil-structure interaction systems such as multi-span bridge structures and frame structures with shallow foundations, as well as complex soil-structure interaction systems such as pile foundations surrounded by liquefied sites, jack-up platform foundations, and tunnel-pile-superstructure systems. Later, preliminary investigations of the hybrid simulation of underground structures subjected to strong earthquake motions carried out by the authors' group are briefly introduced. The hybrid test framework for underground structures was established based on the OpenSees-OpenFresco platform and was validated by comparison with finite element results, taking Daikai station as an example. In addition, the accuracy of the hybrid simulation with different loading boundary conditions is also discussed. The results show that the predictions from the proposed virtual hybrid simulation match well with those from the pure finite element simulation. The predicted results are very close under the loading boundary conditions with an inflection point or with a complete three-direction loading subjected to a low-level excitation (0.12g). However, a large difference between the results from these two loading boundary conditions is observed under a high-level excitation (0.58g). Finally, a couple of important unsolved problems, as well as suggestions for future developments in the hybrid simulation of soil-structure interaction systems, are also discussed in this paper.