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随着城市轨道交通工程抗震性能越来越受到关注,反应位移法作为一种简捷的抗震设计方法被大量应用于地下结构抗震设计中。地基弹簧系数的确定方法是反应位移法抗震设计中最为重要的因素之一,本文选取试验法、李英民法、MIDAS法和有限元法,结合北京典型地层,对比分析这四种方法地基弹簧系数取值对地下结构的弯矩、轴力和剪力的影响规律。结果表明:(1)在反应位移法计算中,地基弹簧系数取值对结构内力响应具有重要影响,对结构轴力和剪力的影响较大,而对于弯矩的影响相对较小;(2)地基弹簧系数获取方法优选试验法,在无地勘资料情况下,经验公式和有限元法可作为备选方法;(3)综合考虑四种不同地基弹簧系数确定方法对结构内力影响程度,为保证结构设计的安全性,可对试验法下结构内力进行系数修正,修正系数建议值为1.10。
As the seismic performance of urban rail transit projects is getting more and more attention, reactive displacement method is widely used in seismic design of underground structures as a simple and effective method of seismic design. The method of determining the foundation spring coefficient is one of the most important factors in the seismic design of reaction displacement method. In this paper, the test method, the Liying civil law, the MIDAS method and the finite element method are combined with the typical formations in Beijing to compare and analyze the spring coefficient The influence of value on the moment, axial force and shear force of underground structure. The results show that: (1) In the calculation of reaction displacement method, the value of the foundation spring coefficient has an important influence on the internal force response of the structure, but has a great influence on the axial force and the shear force of the structure, while the influence on the bending moment is relatively small; (3) Considering the influence of four different methods of determining the spring coefficient of foundation on the internal force of structure, the empirical formula and finite element method can be used as an alternative method. To ensure the safety of the structural design, the structural internal forces under the test method can be corrected by a factor of 1.10.