Recent Advances in Horizontal Jet Grouting (HJG): An Overview

Abstract

This paper discusses recent advances in the implementation of horizontal jet grouting (HJG) for the ground improvement of soft soil. Field trials of HJG were undertaken in soft soils in Shanghai, and the research is reported and discussed in this paper. Particular emphasis was placed to study the hardening process in non-cohesive soils. The recent innovations in HJG were found to arise principally from challenges in implementing jet grouting in sandy soil and also from the harmful effects on the surrounding caused by the traditional implementation process. Accordingly, the recently developed composite jet pipe, pressure-control jet grouting and control discharge horizontal jet grouting methods have been successfully implemented to mitigate the ground upheaval and displacements. Moreover, the characteristics of the jet grout columns obtained with these methods were found as a rule to perform beyond expectations. It was also found that the newly developed horizontal twin-jet grouting technology, underpinned by an instant-solidification mechanism, overcame challenging issues such as mixing uniformity, loss of admixture and hardening. The characteristics of hardening in particular have initiated new perspectives, given that a better acquaintance of the mechanisms of hardening and ground displacements is bound to play an important role in the future practice and the development of the jet grouting process. Interestingly, smoothed particle hydrodynamics technique was found to be suited for modeling jet grouting mechanisms.