Actors Affecting Field Settlement Assessment And Back-Analysis By The Asaoka And Hyperbolic Methods

Thick deposits of marine clay are commonly present in coastal regions of the tropics. Land reclamation on this marine clay formation will require some form of ground treatment works to accelerate the consolidation process. The aim of ground treatment works is to negate settlements under the fill load, future dead and live loads. The use of prefabricated vertical drains with a preloading option is the most widely used ground improvement method for the improvement of marine clays in land reclamation projects. After taking into account the submergence effect and settlement of the reclaimed land surcharge of the equivalent working load is placed until the required degree of consolidation of the marine clay is obtained. As such, the assessment of the degree of consolidation of the marine clay is of paramount importance prior to the removal of the preload. The most suitable means of carrying out this assessment is by means of field settlement monitoring. During the process of consolidation, the field settlement monitoring data can be analysed by means of the Asaoka and hyperbolic methods to predict the ultimate settlement and the degree of consolidation of the underlying soft marine clay. There are various factors that affect the predictions by these methods such as the period of assessment after surcharge placement and the time interval used for the assessment. The aim of the paper is to highlight the significance and impact of these factors on the field settlement assessment and the back-analysis of the coefficient of consolidation due to horizontal flow of soft clays and with special regard to coastal marine clays.