Studies on Seismic Safety of Structure-Soil Interaction System and Its Rational Design Procedures

本研究旨在通过对大型扩展土木工程结构进行分析，重点研究土-结构动力相互作用，从而为大型扩展土木工程结构的设计提供有用信息。重点研究了以下问题：(1)地震波在土质沉积物中随地形变化的传播；(2)土-结构动力相互作用与地基阻抗及有效输入运动；(3)强震运动中土体的非线性效应对结构响应的影响；(4)多输入结构的渐进输入运动。采用了频域分析、时域分析及其混合分析方法。使用的参数是入射波类型、入射角、地形、土壤沉积物的宽深比。分析了由表面宽度和入射波长定义的具有代表性的无量纲频率。局部地形引起的土壤放大主要取决于波浪类型和面维频率。针对集中力和均匀分布力，提出了边界元法分析所涉及的格林函数。傅里叶变换法需要对反变换进行波数积分。这是通过高斯正交和改进的克伦肖-柯蒂斯方法来实现的。多层的Green函数使得分层半空间的土壤沉积成为可能。对间接边界元法中源力的偏移进行了详细的讨论。时域分析采用Cgniad-de Hoop法对全平面的解析解进行求解。群桩基础是在软土上建造的，用于支撑上部结构。本分析充分考虑了桩-土-桩的相互作用。采用下部结构法，将土与桩分离。土壤分析采用薄层法进行。从质量离散系统和质量分布系统两方面对桩进行分析。重点研究了桩顶阻抗函数。对单桩荷载试验进行了模拟。本文还对刚性埋地基础的分层、相邻基础与土的相互作用、回填效应等问题进行了研究。在强地震动条件下，土体具有较高的应变，表明在非周期性地震输入条件下，土体具有严重的非线性行为。在一定的应力应变关系下，采用直接分步积分法和基于有效应变的等效法分别对一维和二维模型进行了响应计算。对时间历程和响应谱进行了比较。阐明了建模的区别和非线性的特点。为了解释记录数据，强调了二维建模的重要性。研究了非线性土体条件下桩支结构的响应，并进行了等效线性分析。土体变形是基于假定的土体应力-应变特性。虽然等效线性化技术可以合理地预测真正的非线性响应，但随着输入运动的增加，这些响应之间的差异变得明显。特别是，这种非线性结构响应导致加速度减小而位移放大。少

This study aims at getting useful information for design of extended large scale civil engineering structures through the analysis of such structures with emphasis on dynamic soil structure interaction. The following issues has been focused :(1) Wave propagation in the soil deposit with the local topography(2) Dynamic soil-structure interaction and the foundation impedance and the effective input motion(3) Nonlinear soil effect in strong earthquake motion on structural response(4) Progressive input motion to multiple input structuresTopographical study of the construction site is made to investigate the seismic wave amplification in 2 dimensional sense. The frequency domain analysis, the time domain analysis and their hybrid approach have been employed. The parameter used are the incident wave types, angle of incidence, topography, aspect ratio between wide and depth of the soil deposits. Analysis is conducted for representative nondimensional frequency as defined by the surface width … More of the deposit and the incident wave length. Soil amplification due to the local topography depends significantly on the wave type and noodimension frequency.The Green function involved for the BEM analysis is developed for the concentrated as well as uniform distributed forces. The Fourier transform method needs the wave number integration for the inverse transform. This is performed by the Gauss quadrature and by the modified Clenshaw-Curtis method. The Green function for multilayer makes it possible to perform the soil deposits with layered half space. Detail discussion is made for the offset of source forces in the indirect boundary element method. The time domain analysis used the Cgniad-de Hoop method for the analytical solution for a full plane.Group pile foundations are constructed on soft soils to support superstructures. The present analysis took deliberate consideration for the pile-soil-pile interaction. The substructure method is used to advantage, splitting the soil and piles. The soil analysis is performed by use of the thin layer method. The pile analysis is made from the mass discrete system and the mass distributed system. The investigation is focused the pile head impedance function. The simulation is carried out for a single pile loading test.The investigation for rigid buried foundations is also executed with interest to soil layering, the interaction between adjacent foundation through soil, fillback effect.Soils in strong ground motion attain high strains, indicating heavily nonlinear behavior with drift of the base line for the nonperiodic seismic input. Assuming certain stress-strain relationship, response computation are made for the 1-dimensional and the 2-dimensional models by the direct step-by-step integration scheme and by the equivalent method based on effective stain. The results are compared for the time histories and the response spectra. The difference of modeling and the characteristic of nonlinearity are clarified. The importance of the 2-dimensional modeling is emphasized in order to interpret the recorded data.Pile supported structural response with nonlinear soil properties is investigated, together with the equivalent linear analysis. Soil-deformation is based on the assumed soil stress-strain characteristic. Although the equivalent linearization technique predicts reasonably the truly nonlinear response, the difference between these responses becomes appreciable as the input motion grows. Especially, such nonlinear structural response gives rise to reduced acceleration but amplified displacement. Less