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