To investigate the liquefaction mitigation capability of Rammed Aggregate Piers® (RAP) in silty sand, blast liquefaction testing was performed at a soil profile treated with a full-scale RAP group relative to an untreated soil profile. The RAP group consisted of 16 piers in a 4x4 arrangement at 2 m center-to-center spacing extending to a depth of 9.5 m. Blasting around the untreated area induced liquefaction (ru ≈1.0) from 3 m to 11 m depth, producing several large sand boils, and causing settlement of 10 cm. In contrast, installation of the RAP group reduced excess pore water pressure (ru ≈0.75), eliminated sand ejecta, and reduced average settlement to between 2 to 5 cm when subjected to the same blast charges. Although the liquefaction-induced settlement in the untreated area could be accurately estimated using the CPT-based settlement approach proposed by Zhang et al. (2002), settlement in the RAP treated area was significantly overestimated with the same approach even after considering RAP treatment-induced densification. Analyses indicate that settlement after RAP treatment could be successfully estimated from elastic compression of the sand and RAP acting as a composite material. The composite reinforced soil mass, surrounded by liquefied soil, transferred load to the base of the RAP group inducing settlement in the non-liquefied sand below the group. This test program identifies a mechanism that explains how settlement was reduced for the RAP group despite the elevated ru values in the silty sands that are often difficult to improve with vibratory methods.
| Identifer | oai:union.ndltd.org:BGMYU2/oai:scholarsarchive.byu.edu:etd-9530 |
| Date | 16 June 2020 |
| Creators | Andersen, Paul Joseph Walsh |
| Publisher | BYU ScholarsArchive |
| Source Sets | Brigham Young University |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | Theses and Dissertations |
| Rights | https://lib.byu.edu/about/copyright/ |
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