Plane‐strain model for large strain consolidation induced by vacuum‐assisted prefabricated horizontal drains

Abstract

Vacuum-assisted prefabricated horizontal drain (PHD) can be used to accelerate the consolidation process of dredged mud slurry with high water content, and this method exhibits advantages over traditional treatment methods that use prefabricated vertical drain (PVD). However, large-strain model that can simulate soil consolidation induced by vacuum-assisted PHDs is missing in the literature, although the large-strain models for PVD-induced radial consolidation are abundant. This study presents a piecewise-linear plane-strain model for large-strain consolidation induced by vacuum-assisted prefabricated horizontal drains. The model is called PCS, abbreviation for Plane-strain Consolidation Settlement. PCS model can account for complex conditions including large strain, multiple layers of PHD boards, staged filling of soil layers, varying spacing of PHD boards, time-dependent surcharge and/or vacuum loading, soil self-weight, nonlinear compressibility, and hydraulic conductivity during the consolidation process, vertical and horizontal flows, and non-Darcian flow. The PCS is validated using the two-dimensional Terzaghi's consolidation theory (small strain) and a largescale laboratory model test (large strain), which involves multiple soil layers filled in stages, multiple PHD layers, and different horizontal spacings of PHD boards. Lastly, the proposed model is applied to a case study conducted at Shimokita Peninsula (Aomori Prefecture, Japan), where vacuum-assisted PHDs have been used to treat the dredged mud slurry for a duration of 330 days.