Abstract:
In this study, the consolidation deformation behavior of the new Bangkok - Chonburi
Highway Project (section 2-A/2), which is improved by prefabricated vertical drains (PVD) ,
is analyzed. Predictions of ground movement are compared with the measured data from the field
observations. The back-calculated soil parameters from the field data and the laboratory test
results, namely: Coefficient of consolidation (Ch ) , undrained Young's modulus (Eu ) ,were
investigated. The Ch values were overestimated by the method of Asaoka(1978) when the
during-construction time-settlement curved was used. The Ch values should be back-calculated
from the post-construction field data. The following correlation is found: Eu =133Su ; where
Su is corrected undrained shear strength. Predicted values have been compared with field data in
terms of settlement, lateral movement and excess pore water pressure. For construction
settlements, the one-dimensional consolidation method (Terzaghi, 1943) , the Skempton &
Bjerrum (1957) method and the finite element method (FEM) overpredicted the settlement of
during-construction stage but give good agreement at post-construction stage. The Asaoka (1978)
method shows good agreement. The FEM overpredicted the lateral movement at early stage of
construction but underpredicted at the end of construction. It also underpredicted the excess pore
water pressure of both during-construction and the end of construction stage. For the case
analyzed, the PVD can improved the mass permeability( k) about 20 - 200 times higher than the
original permeability, and the increase of Young's modulus (Es) values in the fill material can
reduced the lateral movement.