Volume 3, Issue 1 — Year 2026 — Article e100059

ISSN (Online): 3115-8129 Biannually

Effect of a Soil Buffer Layer on the Seismic Response of Rocking-Based Isolation Systems in Soft Soil

Article Type: Research
Pages: e100059
DOI: https://doi.org/10.22034/CGEL.3.1.e100059
Crossmark
Open Access
Authors
Affiliations
  1. Department of Civil Engineering, University of Tabriz, Tabriz 5166616471, Iran
Corresponding author
Email: ali.parto.gh@gmail.com
ORCID: 0009-0007-4081-1245
Received: 10 February 2026 / Accepted: 20 April 2026 / Published: 25 May 2026
Abstract

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.

Keywords

Soil layer, Rocking isolation, Soft soil, Granular soil, Recentering ratio

Data availability statement

The data supporting the findings of this study are available from the corresponding author upon reasonable request. No publicly archived dataset was generated.

Funding

This research received no external funding.

Highlights
  • Buffer layer improves rocking isolation on soft soils
  • Optimal thickness balances rotation and settlement
  • System enhances recentering performance
References
  1. Allmond J.D., Kutter B.L. (2014). Design considerations for rocking foundations on unattached piles. Journal of Geotechnical and Geoenvironmental Engineering, 140(10), 04014058. https://doi.org/10.1061/(ASCE)GT.1943-5606.0001162.
  2. Amiri A., Hosseini S.M.M.M., Soroush A. (2025). Experimental study of influencing pile to cap connections on the rocking behaviors of piled foundations. Scientific Reports, 15(1), 14937. https://doi.org/10.1038/s41598-025-98940-x.
  3. Anastasopoulos I., Gazetas G., Loli M., Apostolou M., Gerolymos N. (2010). Soil failure can be used for seismic protection of structures. Bulletin of Earthquake Engineering, 8, 309-326. https://doi.org/10.1007/s10518-009-9145-2.
  4. Bin J., Huang Z., Wu J., Pan P., Jing L. (2024). Influence of rocking shallow foundation parameters and analysis of seismic response characteristics. Buildings, 14(12), 3788. https://doi.org/10.3390/buildings14123788.
  5. Deng L., Kutter B.L., Kunnath S.K. (2012). Centrifuge modeling of bridge systems designed for rocking foundations. Journal of Geotechnical and Geoenvironmental Engineering, 138(3), 335-344. https://doi.org/10.1061/(ASCE)GT.1943-5606.0000605.
  6. Gajan S., Kutter B.L. (2008). Capacity, settlement, and energy dissipation of shallow footings subjected to rocking. Journal of Geotechnical and Geoenvironmental Engineering, 134(8), 1129-1141. https://doi.org/10.1061/(ASCE)1090-0241(2008)134:8(1129).
  7. Hakhamaneshi M., Kutter B.L. (2016). Effect of footing shape and embedment on the settlement, recentering, and energy dissipation of shallow footings subjected to rocking. Journal of Geotechnical and Geoenvironmental Engineering, 142(12), 04016070. https://doi.org/10.1061/(ASCE)GT.1943-5606.0001564.
  8. Irani A., Bonab M.H., Assadi-Langroudi A., Maleki Tabrizi E. (2024). Pore-pressure-dependent performance of rocking foundations. Soil Dynamics and Earthquake Engineering, 183, 108772. https://doi.org/10.1016/j.soildyn.2024.108772.
  9. Irani A., Bonab M.H., Sarand F.B., Katebi H. (2023). Overall improvement of seismic resilience by rocking foundation and trade-off implications. International Journal of Geosynthetics and Ground Engineering, 9(4), 40. https://doi.org/10.1007/s40891-023-00454-x.
  10. Irani A.E., Bonab M.H., Sarand F.B., Katebi H. (2021). Behavioral evaluation of soil-based rocking foundations against seismic loading: A review study. Geotechnical Geology, 17(1), 455-463.
  11. Irani A.E., Bonab M.H., Sarand F.B., Katebi H. (2023). Investigation on the behavior of bridge piers considering rocking isolation constructed on non-plastic silts and sands using 1g shaking table tests. Periodica Polytechnica Civil Engineering, 67(3), 835-845. https://doi.org/10.3311/PPci.21713.
  12. Itasca (2020). Fast Lagrangian Analysis of Continua in 3 Dimensions: User’s guide (Version 6.0). Itasca Consulting Group, Minneapolis.
  13. Ko K.W., Ha J.G., Park H.J., Kim D.S. (2019). Centrifuge modeling of improved design for rocking foundation using short piles. Journal of Geotechnical and Geoenvironmental Engineering, 145(8), 04019031. https://doi.org/10.1061/(ASCE)GT.1943-5606.0002064.
  14. Moradi M., Hosseini S.M.M.M., Khezri A. (2023). Investigation of rocking mechanism of shallow foundations on sand via PIV technique. Earthquake Engineering & Structural Dynamics, 52(6), 1762-1784. https://doi.org/10.1002/eqe.3842.
  15. Moradi M., Khezri A., Hosseini S.M.M.M., Park H., Lee D. (2024). Experimental investigation of embedment depth effects on the rocking behavior of foundations. Geosciences, 14(12), 351. https://doi.org/10.3390/geosciences14120351.
  16. Nikvand V., Bonab M.H. (2024). Seismic response analysis of tunnels using a coupled polygonal finite element method. Civil and Geoengineering Letters, 1(1), e100009. https://doi.org/10.22034/CGEL.1.1.e100009.
  17. Rassoulpour S., Shiravand M.R., Safi M. (2025). Effect of soil-structure interaction on seismic behavior of self-centering rocking piers supported on shallow foundations. Soil Dynamics and Earthquake Engineering, 194, 109339. https://doi.org/10.1016/j.soildyn.2025.109339.
  18. Sadjadi M., Fadaee M., Ghannad M.A., Jahankhah H. (2023). Seismic performance of deformable rocking soil-structure systems subjected to pulse-type excitations. Journal of Earthquake Engineering, 27(12), 3290-3318. https://doi.org/10.1080/13632469.2022.2134232.
  19. Xiong G., Wang F., Zhou F. (2024). Torsional and rocking response analysis of foundations subjected to spatially inclined incident SV waves considering soil nonlinearity. Soil Dynamics and Earthquake Engineering, 184, 108868. https://doi.org/10.1016/j.soildyn.2024.108868.
How to cite
Parto, A. G. (2026). Effect of a Soil Buffer Layer on the Seismic Response of Rocking-Based Isolation Systems in Soft Soil. Civil and Geoengineering Letters, 3(1), e100059. https://doi.org/10.22034/CGEL.3.1.e100059
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