摘要:我国地下工程结构的抗震设计主要采用等效静力法,国外则提出了自由场变形法、反应位移法等方法。本文分析评价等效静力法、自由场变形法和反应位移法应用于软土地下结构抗震设计的差异。分析中设定表征软土地下结构的基准模型,并以动力时程分析给出地下结构的地震响应。假定地质条件和结构埋深不变,通过比较分析随基准模型的结构刚度变化时计算变形和内力的差异,评价三种拟静力地下结构抗震设计方法的适用性。结果表明,等效静力法对刚度较大的浅埋框架结构适用性较好,其它情况计算的结构变形和内力偏大;自由场变形法适用于浅埋框架结构刚度较小或与周围地层刚度接近的情况,且倒三角形分布力模式优于集中力模式;反应位移法可适用于不同刚度软土浅埋框架结构的抗震设计。
Abstract: So far, Equivalent Static Method has been mainly used in the seismic design of underground structures in China; however, Free-filed Deformation Method and Response Displacement Method have been mainly used in foreign countries. The seismic design discrepancy of Equivalent Static Method, Free-field Deformation Method and Response Displacement Method was analyzed and evaluated in this paper. In analysis, the benchmark model was set for underground structure in soft soils, and the seismic response of underground structure was acquired by using dynamic time-history analyses. Assuming the same stratum and buried depth, based on the discrepancy comparison analysis of deformation and internal force along with different structural stiffness, evaluation of applicability was made for the three pseudo-static seismic design methods. The result shows: Equivalent Static Method could be applied well under the condition of large stiffness of shallow-buried frame structures in soft soils, in other cases it will lead to large deformation and internal force of structure; Free-field Deformation Method could be applied in the condition that the stiffness of structure is relatively small or approached to the surrounding soil, and the Pseudo-Triangular Pressure Distribution Model would prior to the Pseudo-Concentrated Force Model; Response Displacement Method could be suitable to the seismic design for shallow-buried frame structures with different stiffness.