岩溶地基—筏板基

发布时间：2018-06-07 11:31

  本文选题：地震波反演 + 岩溶地基-筏板基础-钢框架结构共同作用　； 参考：《广西大学》2014年硕士论文

【摘要】：我国岩溶地区的面积约占我国国土总面积的三分之一,是世界上面积最大的岩溶地区之一；我国处在世界两大地震带之间,地震活动频繁,地震造成的灾害也比较大,特别是近些年,每次地震灾害都会造成巨大的伤亡；目前,在岩溶地基上建造高层建筑主要的设计方法仍然采用常规设计方法或者经验法,容易造成人为的误差,特别是对建筑抗震分析时,计算结果与实际的出入会更大,因此加强岩溶地基-基础-上部结构共同作用的研究是非常有必要的。本文采用数值模拟方法对岩溶地基-筏板基础-钢框架结构共同作用进行了以下几方面的研究：(1)采用EduShake软件来对EI-Centro波进行反演,反演地质条件采用岩溶区的一处场地,将EI-Centro波按照规范进行调幅后,从地表处反演至基岩处,经过分析得出岩溶地质对地震波具有放大作用和“滤波作用”。(2)建立岩溶地基-筏板基础-钢框架结构的共同作用模型,通过与地基土体尺寸无限大时的模型作对比,确定了有限元-无限元耦合模型中有限元部分的土体尺寸：当采用有限元-无限元耦合模型来考虑共同作用时,有限元部分尺寸不宜小于15倍的结构横向尺寸。(3)建立岩溶地基-筏板基础-钢框架结构的共同作用模型,通过与地基土体尺寸无限大时的模型作对比,确定了有限元-无限元耦合模型中无限元部分的土体尺寸：即当有限元的延伸长度取值大于有限元-无限元交界面距土体中心尺寸的1.5倍时,误差已经很小,本文有限元的延伸长度取有限元-无限元交界面距土体中心尺寸的2倍。(4)采用得到的耦合模型中土体有限元部分的尺寸和无限元部分的尺寸,建立岩溶地基-筏板基础-钢框架结构的共同作用模型,分析考虑共同作用对上部结构抗震性能的影响。结果表明考虑共同作用以后,上部结构底部变形与内力较不考虑共同作用相比增大较多,随着层数的增加,增大的幅度逐渐减小,产生这种现象的原因是由于考虑共同作用以后,筏板基础产生不均匀沉降,使得框架柱底部产生了较大的次生应力,随着层数的增加次生应力逐渐减小。(5)建立岩溶地基-筏板基础-钢框架结构的共同作用模型,分析土洞的存在对共同作用抗震性能的影响。结果表明地基土中由于土洞的存在,,使得地基土的刚度减小,在地震的作用下导致地基土的变形要比无土洞时大,进而上部结构产生更大的内力和变形。
[Abstract]:The area of karst area in China accounts for about 1/3 of the total land area of our country, and it is one of the largest karst areas in the world. In particular, in recent years, every earthquake disaster has caused huge casualties. At present, the main design methods for building high-rise buildings on karst foundations are still using conventional design methods or empirical methods, which can easily cause man-made errors. Especially for the seismic analysis of buildings, the difference between the calculated results and the actual results will be greater, so it is necessary to strengthen the study of the interaction between karst foundation and superstructure. In this paper, numerical simulation method is used to study the interaction of karst foundation, raft foundation and steel frame structure in the following aspects: the EduShake software is used to inverse the EI-Centro wave, and the geological conditions are retrieved from a site in the karst area. After amplitude modulation of EI-Centro wave in accordance with the specifications, inversion from the surface to the bedrock, it is concluded that karst geology can amplify the seismic wave and "filter" the seismic wave. 2) to establish the mutual action model of karst foundation, raft foundation and steel frame structure. By comparing with the finite element model when the soil size is infinite, the soil size of the finite element part of the finite element coupling model is determined. When the finite element infinite element coupling model is used to consider the joint action, The finite element method should not be less than 15 times the transverse size of the structure.) the model of the interaction between karst foundation, raft foundation and steel frame structure is established, and the model is compared with the model when the soil size is infinite. The soil size of the infinite element in the finite element coupling model is determined. That is, when the extension length of the finite element is 1.5 times larger than that of the interface between the finite element and the infinite element, the error is very small. In this paper, the extension length of the finite element is taken as 2 times that of the interface between the finite element and the infinite element from the center of the soil, and the size of the finite element part of the soil and the size of the infinite element part in the coupling model are obtained. The interaction model of karst foundation raft foundation and steel frame structure is established and the effect of joint action on seismic behavior of superstructure is analyzed. The results show that the deformation at the bottom of the superstructure increases more than that of the internal force without considering the interaction, and with the increase of the number of layers, the amplitude of the increase decreases gradually. The reason for this phenomenon is that considering the joint action, the raft foundation produces uneven settlement, which results in a large secondary stress at the bottom of the frame column. With the increase of the number of layers, the secondary stress decreases gradually.) the interaction model of karst foundation, raft foundation and steel frame structure is established, and the influence of the existence of soil hole on the seismic behavior of the joint action is analyzed. The results show that the stiffness of the foundation soil decreases due to the existence of the soil hole, and the deformation of the foundation soil is larger than that of the non-soil hole under the action of earthquake, and the superstructure produces greater internal force and deformation.
【学位授予单位】：广西大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TU311.3;TU435
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本文编号：1991021