Civil and Geoengineering Letters Editorial Office info@jcivilgeo.com mEDRA 20260525 DOI Registration 01

06 10.22034/CGEL.3.1.e100059 https://jcivilgeo.com/article/e100059 Civil and Geoengineering Letters mEDRA 01 01 3115-8129 Civil and Geoengineering Letters Editorial Office IR 01 3115-8129 JB 3 1 01 202605 1 1 A01 Ali Ghaffarnezhad Parto Ghaffarnezhad Parto, Ali Ali Ghaffarnezhad Parto 01 eng 202605 03 00 Rocking isolation systems founded on soft soils commonly exhibit settlement-dominated responses, leading to accumulated plastic strains and degradation of recentering capacity. Although ground improvement elements reduce total settlement, direct footing–improvement element induces localized stress concentrations that may hinder stable rocking behavior. This study investigates the influence of introducing an intermediate soil layer between the shallow foundation and the improvement elements on seismic response characteristics. A three-dimensional nonlinear finite difference model is developed to simulate a 3 m × 3 m shallow footing supported by discrete pile groups and diaphragm wall systems. A granular sand layer, defined as a soil buffer, is inserted between the footing and the improvement elements. Buffer thicknesses of 0, 60 cm (B/5), and 100 cm (B/3) are evaluated through parametric analysis. The results indicate that increasing buffer thickness reduces peak rotational amplitude; in the pile-supported configuration, rotation decreases from 0.121 rad (no buffer) to 0.083 rad for a 100 cm buffer. While the presence of the buffer increases residual settlement relative to direct-contact systems, increasing it from 2.2 cm to 5.5 cm in JG-PR, settlement remains significantly lower than the unimproved condition (13.6 cm). Among the examined cases, a thickness of 60 cm (B/5) provides the most favorable balance between rotation control and recentering, with the diaphragm wall system (JG-PR-SB60) achieving a recentering ratio of 0.987. The findings demonstrate that the buffer layer modifies the contact stress transfer mechanism, promoting distributed shear deformation within the interface zone and reducing localized bearing concentration at improvement elements. 20 Soil layer; Rocking isolation; Soft soil; Granular soil; Recentering ratio 01 00 20260210 02 00 20260420 2026 Ali Ghaffarnezhad Parto