饱和土—基

发布时间：2018-04-08 15:43

本文选题：饱和土　切入点：土-结构相互作用　出处：《南京航空航天大学》2017年硕士论文

【摘要】：地震波入射时土与结构动力相互作用分析是地震工程领域的重要问题。基于问题的复杂性,过往的研究大多将地基土考虑为干土。而在实际工程中,土体中经常充满孔隙水,孔隙水对土层的地震反应影响较大,进而影响支撑于其上的基础和上部结构的响应。因此,有必要考虑饱和土-基础-结构动力相互作用问题。本文将三维土-基础-结构动力相互作用分析方法推广到饱和地基情形,并对饱和地基上的相互作用进行了简要探讨。本文的主要工作如下:(1)基于Biot模型,推导并实现了传递矩阵方法用于饱和成层土体在地震波入射时的反应分析。通过数值算例,验证了该方法的有效性,发现和初步阐明了计算中出现的两类违背因果律(即响应先于输入)的现象,据此得到了满足因果律的参数范围,该范围可作为实际计算时的一个上界。(2)采用时空分区显-隐式异步算法,通过FORTRAN程序实现了三维饱和土-基础-结构相互作用的时域直接分析方法,通过与显-隐式同步算法的对比算例,验证该异步算法在满足精度的前提下,可较大提高计算效率。(3)实现柔性基础情形的饱和土-基础-结构动力相互作用分析。通过算例对比,考量刚性基础数值模拟过程的合理性与柔性基础计算失稳问题。(4)将干土统一到饱和土的计算框架中,进一步实现了干土与饱和土混合情形时的土-结构动力相互作用分析,使得问题的模拟更贴近实际工程(如考虑地下水位情形)。通过算例对比了饱和土地基、干土地基、干土覆盖饱和土地基情形时,土-结构相互作用对基础和结构响应的影响,结果表明地下水位对基础和结构响应的影响较大。(5)基于不规则加卸载准则的修正Davidenkov模型,考虑饱和土骨架的非线性特性,以一三维饱和土体及一框架结构与饱和土体相互作用问题为算例,分别考虑饱和土体为线性和非线性情形,对比分析了非线性对饱和土体、基础和结构反应的影响。
[Abstract]:The analysis of dynamic interaction between soil and structure is an important problem in the field of seismic engineering.Due to the complexity of the problem, most previous studies have considered the foundation soil as dry soil.In practical engineering, the soil is often filled with pore water, which has a great influence on the seismic response of the soil layer, and then affects the response of the foundation and the superstructure supported on it.Therefore, it is necessary to consider the saturated soil-foundation-structure dynamic interaction.In this paper, the three-dimensional soil-foundation-structure dynamic interaction analysis method is extended to the saturated foundation case, and the interaction on the saturated foundation is discussed briefly.The main work of this paper is as follows: (1) based on the Biot model, the transfer matrix method is derived and realized for the response analysis of saturated layered soil under the incident seismic wave.The validity of the method is verified by numerical examples, and two kinds of phenomena of violating causality law (i.e. response before input) are found and preliminarily clarified, and the range of parameters satisfying the causality law is obtained.This range can be used as an upper bound in practical calculation. (2) A direct time-domain analysis method of three-dimensional saturated soil-foundation structure interaction is realized by FORTRAN program using spatial-temporal explicit implicit asynchronous algorithm.By comparing with the explicit and implicit synchronous algorithm, it is verified that the asynchronous algorithm can greatly improve the computational efficiency on the premise of satisfying the accuracy. It can realize the saturated soil-foundation structure dynamic interaction analysis in the case of flexible foundation.Considering the rationality of the numerical simulation process of rigid foundation and the instability problem of flexible foundation calculation, the dry soil is unified into the calculation frame of saturated soil.Furthermore, the soil-structure dynamic interaction analysis in the case of dry soil and saturated soil is realized, which makes the simulation of the problem more close to the actual engineering (for example, considering the groundwater level case).The effects of soil-structure interaction on the foundation and structural response of saturated soil foundation, dry soil foundation and dry soil covering saturated soil foundation are compared by numerical examples.The results show that the influence of groundwater level on the response of foundation and structure is great. (5) based on the modified Davidenkov model of irregular loading and unloading criterion, the nonlinear characteristics of saturated soil skeleton are considered.Taking the one dimensional saturated soil and the interaction between a frame structure and saturated soil as an example, the effects of nonlinearity on saturated soil, foundation and structure response are compared and analyzed, respectively, considering the linear and nonlinear cases of saturated soil.
【学位授予单位】：南京航空航天大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU435

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