Offshore deep cement mixing with rope suspended equipment

Abstract

Land expansion projects, by essence, involve the permanent occupation of marine spaces. Expansion of port terminals and reclamation projects often require preliminary ground improvement as the existing seabed properties are not always sufficient to provide enough stability and/or bearing capacity to support a significant increase of loading. Amongst the potential ground improvement technologies applicable, non-dredging techniques such as offshore deep cement mixing become of growing interest as they prevent the displacement of huge volumes of marine sediments, reduce the impact on water quality as well as marine species and are usually faster to complete.This article first presents the use of a rope suspended low headroom deep cement mixing equipment involving diaphragm wall cutter technology and working from floating barge vessel on anchors with air draft as low as six meters from sea surface. Then, after introducing the technical and environmental challenges linked to the offshore context, innovative marine applications are then presented through various case histories: load transfer platform for reclamation project, shear walls, offshore liquefaction mitigation for construction of a new wharf and a retaining wall for the deepening of an existing quay.