The performance of a prefaricated vertical drain trial embankment

Abstract

Two fuel scale trial embankments were constructed to a height of 3.65 m over the soft marine clay at Juru, Butterworth, Pulai Pinang. One of the embankments was improved using prefabricated vertical drain (PVD), and the the one without treatment was a control embankment. Monitoring instruments such as hydrostatics profile gauges, settlement gauges, inclinometers and piezometers were installed in the subsoil to observe the deformation behavior of the embankments under loadings. The hyperbolic and the Asaoka's methods were used to predict the total primary consolidation settlement. The embankment with PVD helped to accelarate the consolidation settlement as compared to the control embankment. it can be seen from the back analysis that the performance of the vertical drains is well predicted with smear effect taken into consideration using Kl/Ks=10, s=2.5 and Ch=4.5m2/year. In addition insitu vane shear strength, the compression ratio (CR) and preconsolidation pressures of the subsoil after treatment with PVD had improved substantially. The hyperbolic equation was also used to predict ultimate lateral deformation for both the treated and control embankments. The "R" squares of the linear regression showed reasonable linearity between t/d versus t where t is time and d is the lateral deformation.