Prefabricated Vertical Drains to dissipate excess pore pressures during Dynamic Compaction of Clayey Sands with 30-45% Fines Content

ABSTRACT: A proposed Electric Vehicle (EV) assembling facility, located in the Eastern Seaboard of Thailand, required soil improvement
to enhance the mechanical properties of the clayey sands (SC). Albeit not the ideal soils for energy densification, Dynamic Compaction (DC)
+ Prefabricated Vertical Drains (PVD's) were chosen as the most suitable Soil Improvement technique to increase the strength of the soil and
reduce the future differential settlements resulting from the loads onto the proposed slab-on-grade foundation structure. Given the presence of
the water table within reach of the DC influence, and the high fines content of the soil (30% to 45%), PVD's in advance of DC were designed
to quickly dissipate the excess pore pressures resulting from the dynamic compaction operations and hence, allow the continuation of the works
without the risk of loss of strength in the soil and thus, reducing the dissipation times from 30 to 60 days (without PVD’s) to about 2 to 4 days
(with PVD’s). Instrumentation of Cone Penetration Tests (CPT's), standpipe and vibrating wire piezometers were installed at the project. This
paper focuses on the role of the PVD's as drainage elements for the quick bursts in pore pressure and the results are presented herewith.

KEYWORDS: Prefabricated Vertical Drains, Dynamic Compaction, Pore Pressure Dissipation, Soil Improvement, High Fines Content