Settlements of Bangna‐Bangpakong Highway on Soft Bangkok Clay

Abstract

Time‐settlement data of more than 30 different sections of the 55‐km long Bangna‐Bangpakong Highway in Thailand are analyzed. The deformation parameters, namely: undrained modulus, $E_u;$ drained modulus, $E^{\prime };$ and coefficient of consolidation, $C_v\text{,}$ are backfigured from the field performance of the highway embankment, and the following correlations are found: $E_u/S_{\mathrm{uv}}=150;$ $E^{\prime }/S_{\mathrm{uv}}=15;$ and $C_v\left(\mathrm{field}\right)/C_v\left(\mathrm{lab}\right)=26;$ where $S_{\mathrm{uv}}$ is the uncorrected vane shear strength. It was also found that $C_v$ values are overestimated by the method of Asaoka when the during‐construction time‐settlement curve is used, and are best estimated when backfigured from postconstruction performance. It is also found that for construction settlements, the method proposed by Cox, which is a combination of the method of D'Appolonia et al. for immediate settlements and that of Leroueil et al. for consolidation settlements, underpredicts settlements at some sections but yields conservative estimates when considering secondary settlements since the beginning of construction. Prediction of long‐term settlements yields a good estimate for firmer sections using the method of Skempton and Bjerrum, while the method of Asaoka generally underpredicts. The elastic method of Davis and Poulos gives the best estimates of both construction and postconstruction settlements when backfigured parameters are used.