CONSOLIDATION ANALYSIS OF PVD-IMPROVED SOFT GROUND WITH PRESENCE OF SAND SEAM LAYERS PHÂN TÍCH ỨNG XỬ CỐ KẾT NỀN ĐẤT YẾU CÓ LỚP CÁT MỎNG GIA CỐ BẰNG BẤC THẤM

Abstract

In soft ground engineering, the thin san layer (or sand seam) in the soft soil layer can be formed naturally or artificially. The thin sand layer is deposited in the natural ground between clay layers (e.g., Busan clay). However, the effects of sand seam on consolidation behavior (settlement and pore water pressure dissipation) predicted from analytical models was often ignore due to the complexity in those analytical solutions. Therefore, this paper carries out an analysis of the consolidation behavior of the composite foundation of prefabricated vertical drains (PVDs) system combined with thin sand layer system. A series of numerical analysis is conducted to analyze the influence of thin sand layer on the consolidation settlement of the composite foundation. Analytical solution is also performed and compared with the results of numerical simulations. The obtained results show that the consolidation process of soft ground with the thin sand layer presence occurs faster than that of soft ground without sand seam (or homogeneous ground). The consolidation rate of composite ground depends on the quantity of thin sand layers in the ground. The presence of a thin layer of sand also affects the dissipation of excess pore water pressure in the horizontal direction. The results of numerical analysis show that the settlement of soft ground with the thin sand layer the presence is smaller than that of soft ground without sand seam layer. When the total thickness of the thin sand layers in composite foundation is the same, the settlements tend to be the same.