Jet Grouting

Ground improvement methods are becoming increasingly popular in geotechnical engineering to solve construction problems and to offer new design solutions. In fact, in recent years, significant industrial research has been carried out in developing and refining several ground improvement techniques. As a consequence, new technologies, materials, and applications are regularly proposed on the market and offered to the practitioner as a convenient solution to his problems. Ground improvement techniques are now important arrows in the quiver of design solutions of geotechnical engineers, and there are a few major projects carried out without using at least one of them. In fact, the availability of such new technologies has significantly widened the range of design alternatives. However, continuous technical evolution and rapidly expanding areas of application pose new problems to the geotechnical engineers, who are not always provided with relevant experience on this topic. Actually, in many cases, the ground improvement issues are only roughly considered at the design stage, and their solution is largely left to the specialised contractor. As a result, the designer may partly lose the control of the whole geotechnical process. It follows that ground improvement technologies are often used without the same design care that is usually adopted for other traditional technologies— simply adopting them because they may help or even because more is better—thereby a bit like adding suspenders to a belt. However, by following such approach, the rational base of the scientific method, which should always be the guiding light at the base of a correct design, may be substantially betrayed. Whatever the case, ground improvement techniques often form a grey part of design, where unforeseen problems may hide. This is typical of all situations in which technology has a turbulent growth, and basic research, education, and knowledge dissemination have not been able to keep pace. Fortunately, in the last decade or so, there have been an increasing number of scientific articles and some books devoted to ground improvement. In addition, university courses specifically focused on ground improvement are spreading worldwide, and even the most sceptical geotechnical engineers have recognised that these technologies, if correctly designed and controlled, are a providential opportunity and not just a new problem. Indeed, it is all a matter of knowledge and confidence, and the problem is not the technology but its use or misuse—a perennial question common not only to geotechnical engineering.