Centrifuge Modeling and Mitigation of Manhole Uplift due to Liquefaction

• Published in: Journal of geotechnical and geoenvironmental engineering 2013-03, Vol.139 (3), p.458-469
• Main Authors: Kang, Gi-Chun, Tobita, Tetsuo, Iai, Susumu, Ge, Louis
• Format: Article
• Language: English
• Subjects: Applied sciences; Backfill; Buildings. Public works; Centrifuges; Dynamics; Exact sciences and technology; Geotechnics; Liquefaction; Manholes; Measurements. Technique of testing; Porosity; Soil mechanics. Rocks mechanics; Structure-soil interaction; Technical Papers; Uplift; Water pressure
• ISSN: 1090-0241; 1943-5606
• DOI: 10.1061/(ASCE)GT.1943-5606.0000769

AbstractBecause low-compacted trench backfill around a manhole is normally liquefiable, the manhole could suffer uplift damage associated with soil liquefaction during a strong earthquake. In this study, 22 dynamic centrifuge models were tested to investigate the response of a buried manhole subjected to a dynamic load. The models were tested under 20g, and a substitute pore fluid was used to avoid the scaling law conflict between the dynamic and diffusion processes. It was found that excess pore water pressure is one of the contributing factors to the magnitude of the manhole uplift. Using this result, new mitigation methods against the uplift in liquefied ground were developed. Their effectiveness was also examined through the tests. A model manhole mitigated with the proposed methods was tested alongside regular model manhole. From the test results, the magnitude of manhole uplifts with the mitigation methods decreased as buildup of the excess pore water pressure was restrained in high-compacted backfill or excess pore water was dissipated into the manhole during strong shaking.