Technical Manager Underground Construction

The pre-injection method, or injections ahead of the excavation face in underground construction can in many situations offer significant advantages. This is particularly the case in difficult ground conditions like water ingress or mechanically poor ground or soil, in which pre-injections can contribute to avoid mishaps and serious delays. In sensitive urban environment the need to manage water ingress into tunnels under construction as well as avoiding collapses are crucial factors for the successful completion of a project. Modern pre-injection technology involves the design of methods adapted to the encountered situation. This includes proper drilling techniques and drilling geometry for the best delivery of the grout into the ground, determination of relevant production criteria during the injection, as well as the employment of state-of-the-art injection products like special microcements and colloidal silica. Modern cost-effective material technology for pre-injections in underground construction aims to achieve the desired as fast as possible, hence reducing the down time during the excavation as much as possible In recent years several difficult tasks in tunnelling have been resolved by using modern microcement technology in combination with liquid colloidal silica. Improvement of the technical performance of rapid curing microcements, by using controlled and precise addition of accelerators have made the microcement injection technology far more versatile than before. Two recent, difficult and significantly different projects are reported and discussed in this paper