摘要
地基土体边界条件的确定是土-地下结构动力相互作用(SSDI)问题中的一个重要环节。基于剪切波在土柱中的传播理论,提出一种通过等效土柱模型确定SSDI问题中土体远置自由边界尺寸的方法,即建立土-结构相互作用模型,同时建立有相同土层特性的可代表水平成层无限半空间的等效土柱模型,对二者施加相同的输入地震动激励,当二者土层边界顶部的反应满足相对误差条件时,所选取的土-地下结构体系土体边界尺寸满足波传播的要求。以一个地下隧道工程为背景,基于ABAQUS有限元数值计算平台,应用等效土柱模型确定其远置自由边界尺寸。在此基础上,建立合适尺寸的自由边界模型并对其施加近似粘弹性人工边界及动力无限元边界条件,与通过等效土柱模型确定的自由边界模型的结构反应进行了对比,考察了不同边界条件的设置对结构动力反应的影响。结果表明:对该土-地下隧道工程,通过等效土柱模型确定的可以满足波传要求的自由边界为1 200 m时可控制相对误差在2%以内;自由边界模型与设置了近似黏弹性人工边界及动力无限元边界模型的结构动力反应符合较好;设置近似黏弹性边界及无限元单元的模型能以相对小的计算成本达到与等效土柱模型确定的大尺寸自由边界模型相近的计算效果。确定土体自由边界尺寸的等效土柱模型方法为SSDI问题中土体自由边界的选取与设置提供了有效借鉴与参考。
Determination of soil boundary conditions is one of the most significant issues in dynamic soil-structure interaction problems.A new method to determine far boundary size of soil is derived based on the wave propagation method in horizontal layered soils,ie.,conduct a soil-structure interaction model with far boundary conditions and a horizontal layered soil column model with the same properties at the same time,then the same input ground motions are applied to the bottom of the above two kinds of models,dimension of far boundary is determined when the soil response come out with a small difference between far boundary model and soil column model.Three far boundary models and a soil column model are established based on an immersed tube tunnel site information using the finite element method,and then the far boundary dimension is determined utilizing the above procedures.After that structural responses of the viscoelastic boundary model,the infinite boundary model and the far boundary model are compared with each other.The result shows that:1 200 m soil boundary for the SSI system can satisfy the requirement of wave reflection on the artificial soil boundary;the structural response complied well with each other between the free far boundary model,the viscoelastic boundary model and the infinite model;similar energy dissipation effect can be achieved for both the far boundary model and the energy dissipation models;a good reference for determination of the boundary conditions in dynamic SSI problems is provided utilizing the soil column model method.
作者
田树刚
陈清军
TIAN Shugang;CHEN Qingjun(State Key Laboratory of Disaster Reduction in Civil engineering,Tongji University,Shanghai 200092,China;Research Institute of Structural Engineering and Disaster Reduction,Tongji University,Shanghai 200092,China)
出处
《结构工程师》
北大核心
2018年第5期80-91,共12页
Structural Engineers
基金
国家自然科学基金资助项目(51778489)
国家科技支撑计划项目资助(2015BAK17B04)
