Comparison of predicted and field values of consolidation settlement

Abstract

Construction on soft soil such as clay are generally subject to excessive settlement and the settlement may continue for a long time which depends on the ability if the soil to dissipate excess pore pressure due to construction load. Therefore, the prediction of settlement is important to prevent excessive settlement which can lead to failure. The objective of this study is to predict the settlements using Terzhagi’s 1-D consolidation, Finite Element Method and obtain the actual settlements at site through monitoring instrumentation to achieve the aim of the study which is to compare predicted and field settlements value. This study investigates the consolidation settlement at ongoing project site at Cyberjaya, Selangor which is a lakefront construction. Three Glades which has completed the rest period are chosen for the study. The subsoil of the studied area ranges from 3m to 9m thick deposit of very soft Clay. Embankment heights of 2m to 3m were placed on the overlying soft Clay. Consolidation parameters and the thickness of subsoil layers were defined for this site from soil investigation results and laboratory testing. The predicted settlements were calculated using one-dimensional consolidation theory and Finite Element Analysis by using Soilworks software. The field measurements of settlement were obtained from the settlement gauge which located closest at reference borehole. Based on the analysis prediction using the Finite Element Analysis shows closer which is less than five percent compared to Terzhagi’s 1-D consolidation which varies up to twenty percent compared with values of field measurement except for one Glade which most probably due overestimation of soft Clay thickness. The results of this study confirmed that the 1-dimensional consolidation and finite element theory reasonably estimates the magnitude consolidation settlement for soft clays