Instrumentation and monitoring of a layered clay-sand reclamation

Abstract

Sand fills have been used in Singapore for the last two decades in coastal land reclamations. However, it has become necessary, since late, to import sand from the neighbouring countries for such projects. To reduce the cost of these projects an alternative material was investigated. This led to the use of soft clay and sand in a layered formation in order to reduce the consolidation time. To examine and effect the methods of using marine clay with conventional equipment, a 40 ha land reclamation project was carried out. The dredged clay was hydraulically pumped into an enclosure and then allowed to sediment and consolidate under self-weight until the water content decreased sufficiently. Sand was then spread to form a drainage layer. Several field monitoring devices were used for construction control in order to determine the earliest moment for sand spreading. This paper presents the construction controls adopted and the instrumentation program used.