【作者】 王璐；

【导师】 李英民；

【作者基本信息】 重庆大学 ， 结构工程， 2011， 博士

【摘要】 地下建筑结构由于震害较少且抗震性能优于地上建筑结构,使得其抗震问题没有得到充分的重视,抗震设计理论一直滞后于地上建筑结构。但是,1995年阪神地震中地下结构的严重破坏给传统观念带来了巨大的冲击,地下建筑结构在地震作用下也有可能发生严重的破坏。地下结构往往非常重要,并且一但破坏后难于修复,损失重大。近年来,城市地下建筑结构发展迅速,然而地下建筑结构的抗震设计理论还不够完善,还有很多问题亟待研究。在地下建筑结构抗震设计理论研究越来越无法适应工程实践需要的背景下,本文以地下建筑结构为研究对象,采用理论分析和数值模拟的研究方法,对地下建筑结构的地震反应问题展开了研究,分析了地下建筑结构的地震反应特性与影响因素,改进了地下结构抗震等效侧力法的计算方法,并提出了空间地下建筑结构的三维简化抗震设计计算方法。本文的主要工作和取得的成果有:(1)总结了地下结构震害历史及特征,系统评述了地下结构抗震问题研究方法、现有的地下结构抗震分析与设计方法及其存在的问题,比较了这些方法各自的优缺点和适用性。(2)讨论了地下结构埋深、结构材料性质、土层刚度等因素对地下结构地震反应的影响,并对地下建筑结构与地面建筑结构进行了对比。通过对比地下结构与地面结构的地震反应以及地下结构在不同地基条件时的地震反应可知,在地下结构抗震计算中,应采用能够考虑土体与地下结构之间相互作用的约束条件。(3)在已有基床系数计算公式的基础上,建立了反应位移法和等效侧力法等简化计算方法中地基弹簧系数的经验计算公式,以有限元分析结果为数据基础,对公式的系数进行拟合,并将公式拓展用于成层土体,并选取算例验证了建议公式的合理性和准确性。解决了需要通过有限元法多次计算才能确定地基弹簧系数的问题。(4)归纳总结了地下结构抗震简化计算方法中较为广泛应用的等效侧力法和反应位移法的具体实施步骤、存在的主要问题以及目前的使用情况。在等效侧力法的基础上进行了改进,包括地震荷载的计算公式、土层摩擦力计算公式以及约束条件的施加方法等。并进行了大量的计算分析,验证了改进后等效侧力法的可靠性和适用性。(5)在理论分析的基础上,提出了地下建筑结构的三维抗震简化计算方法,研究了将地下结构平面模型的地震荷载和弹簧约束扩展应用于地下结构空间模型的具体实施方法,并建议了三维简化计算方法中法向和切向地基弹簧系数的经验计算公式。与三维有限元时程分析结果进行对比,验证了该方法的可靠性和适用性。三维抗震简化计算方法的提出,可以解决当空间地下建筑结构不能满足平面应变的假定条件时必须采用三维有限元时程分析进行抗震设计的问题。更多还原

【Abstract】 Studies on seismic design theories for underground structures has lagged behind ground structures for the sake of minor damages and superior seismic performances of underground structures with respect to ground structures. Nonetheless, in Kebo earthquake (1995) serious damges occurred in underground structures, which overturned the tranditional concept. It was discovered that underground structures could encounter serious damages under large earthquake and their recoveries were of high degree of difficulty. Recently, with the repid development of underground structures, advanced seismic design theories are required and munerious problems are urgent for solutions. With the consideration of higher requirement of seismic design theories of underground structures, the dissertation focuses on seismic problems of underground structures. With this in mind, seismic response characteristics and correspongding influencing factors of underground structures are studied by virtue of theoretical analysis and numerical simulations; along the line, the calculation method for equivalent lateral forces is improved; and last but not least a three-dimensional simplified calculation method is proposed for seismic design of underground structures.The major research work and main achievements of this dissertation are detailed as follows:(1) Based on a sketchy summary of damages of underground structures in recent earthquakes, damage characteristics of underground structures are concluded. Also a systematic review on the existing seismic analysis and design methods and the problems encountered are provided. Moreover, the merits and drawbacks of these methods and their applicabilities are compared.(2) Impact of factors including buried depth, structural material properties and soil stiffness on seismic response of underground structures are discussed. Meanwhile, the seismic response of ground and underground structures are compared. It is indicated that interaction between soil and underground structure should be considered in the constraint condition of simplified seismic calculation method.(3) Based on the formula of coefficient of subgrade reaction, empirical formulas are proposed within the framework of the displacement reponse method and the equivalent lateral force method. The relevant coefficients of the proposed formulas are fitted according to the results calculated from finite element analysis. Besides, implementations of the proposed formulas are carried out on layered soil cases, in order to validate their rationality and accuracy.. The empirical formulas renders a favourable access to determine the spring constant of groundwork which otherwise requires several circles of finite element analysis.(4) The solution procedures of the equivalent lateral force method and the displacement response method are provided respectively, which are widely-used in seismic analysis of underground structures. And the main problems and the current application of these methods are presented as well. Moreover, the displacement response method is improved, including the calculation formulas of seismic load and soil shear force and the setup of constraint conditions, Lastly, numerical analysis are conducted to examine the riability and the applicability of the modified displacement response method.(5) Based on theoretical analysis, a three-dimensional simplified seismic calculation method is proposed for seismic design of underground structures. Furthermore, the method to expand the seismic load and spring constraints of plane model to three-dimensional model is studied, and empirical formulas are proposed for the normal and tangential spring constants of the groundwork. Through comparison with three-dimiensional finite element time-history analysis, the rationality and the accuracy of the simplified method are verified. The simplified method is suitable to the cases beyond the plane strain assumption.更多还原