Field instrumentation monitoring of land reclamation projects on marine clay foundations

In land reclamation on marine clay formations, ground improvement works is often necessary to be carried out in order to negate future settlement under the projected dead and live loads. In the case of thick deposits of marine clay, it is necessary to accelerate the consolidation process. The use of prefabricated vertical drains with preloading option is the most widely-used ground improvement method for such cases. In such ground improvement projects in soft soil, the degree of improvement attained by the marine clay has to be ascertained to confirm whether the soil has achieved the required degree of consolidation to enable surcharge removal. This analysis can be carried out by means of observational methods for which continuous records of ground behavior can be monitored from the date of instrument installation. Field instruments are used to verify the performance of the soil improvement works and to ensure that the specified degree of consolidation due to the sandfill and surcharge loading had been achieved prior to the removal of the surcharge. Field instruments installed, monitored and analyzed in such projects include settlement plates, deep settlement gauges, earth pressure cells, pneumatic piezometers, electric piezometers and water-standpipes. The type of field instrumentations installed and their method of analysis is discussed in this paper. Field instrumentation readings obtained at a Case Study Area comprising a Vertical Drain Area (1.5m x 1.5m) and an adjacent Control Area (No Drain) in the land reclamation project is also discussed in this paper.