Abstract The Geotechnical Seismic Isolation (GSI) is recently recommended as an innovative base isolation system placed below the foundation of the superstructure for protection from earthquake damages. Low-shear modulus and high damping material such as Sand-Rubber Mixture (SRM) is used for the GSI layer. However, the compressible nature of SRM in the GSI layer leads to low bearing capacity and high settlement of foundations. In view of this, a GSI system consisting of SRM and geogrid reinforcement is proposed for low-rise buildings in the present study. Finite element based two-dimensional numerical investigation on the seismic performance of a two-storied building supported on raft footing resting on the proposed GSI system was carried out considering the soil–structure interaction. The nonlinearities of the subsurface materials were duly considered using hypoelastic formulations to account for the strain-dependent response. The effectiveness of geogrid reinforcement for the GSI system is demonstrated through seismic settlement analysis based on which optimum geogrid layers were chosen. Effect of various factors such as the thickness of GSI layer, frequency content of earthquake input motions on the seismic demand of the framed structure resting on the proposed GSI system was investigated. While the contribution of SRM was predominant in reducing the peak ground acceleration experienced by the building, the contribution of geogrids was evident in reducing the seismic settlement and lateral deformations on the structure. The results demonstrate the suitability of using the proposed GSI system with a thickness of 0.1B–0.2B (B is the footing width) with double layered geogrid reinforcement in significantly reducing the seismic demands of low-rise building.

中文翻译：

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岩土隔震系统对低层建筑的响应

摘要 岩土隔震系统 (GSI) 最近被推荐作为一种创新的基础隔震系统，放置在上部结构的地基下方，以防止地震破坏。GSI 层使用低剪切模量和高阻尼材料，如砂橡胶混合物 (SRM)。然而，SRM 在 GSI 层中的可压缩性导致低承载力和高地基沉降。鉴于此，本研究提出了一种由 SRM 和土工格栅加固组成的 GSI 系统用于低层建筑。考虑到土 - 结构相互作用，基于有限元的二维数值研究对基于所建议的 GSI 系统的筏基支撑的两层建筑的抗震性能进行了研究。地下材料的非线性被适当地考虑使用低弹性公式来解释应变相关的响应。通过基于选择最佳土工格栅层的地震沉降分析，证明了土工格栅加固对 GSI 系统的有效性。研究了各种因素，如 GSI 层的厚度、地震输入运动的频率成分对基于所提出的 GSI 系统的框架结构的抗震需求的影响。虽然 SRM 的贡献主要是降低建筑物经历的峰值地面加速度，但土工格栅在减少结构上的地震沉降和横向变形方面的贡献是明显的。结果证明了使用厚度为 0.1B-0 的建议 GSI 系统的适用性。