The importance of quality control in jet grouting for deep excavation – A Singapore perspective

摘要

Jet Grouting (JGP) is a construction technique that was developed in Europe in the late 1970s.rnIt has been used worldwide since the 1980s and in Singapore since the early 1980s. Originally developed forrnfoundations, it is now seen as the solution to a number of subsurface problems, and particularly associatedrnwith controlling ground movements for deep excavations in soft clays where it is utilized as a continuous slabrnspanning the excavation width. The designer will specify a thickness, with shear strength (Cu) and an elasticrnmodulus (E) that matches the assumptions for the design and this frequently ends his participation in the process.rnUnfortunately all too commonly this is the easy part of the process and problems that occur during installationrnoften result in the design intent not being achieved. The consequences of this, to the construction projectrnare significant, varying from failure, excessive retaining wall movements. This will impact on thernprogram and eventually lead to cost overrun. Therefore it is of paramount importance that an effective JGPrnslab is installed. To achieve this effective JGP, proven JGP installation procedure should be followed combinedrnwith appropriate quality control and testing of the slab. A number of common pitfalls are discussed inrnrelation to Singapore experience and the appropriate solutions proposed so that an effective and good qualityrnJGP slab can achieved in line with the designers.