Holdfast Training Services Trial Blog

The area on site known as the grout box is due to be handed over from ourselves Laing O’Rourke working on the C502 contract to another contractor working on the c510 contract. The C510 contract is responsible for tunnelling through to the Liverpool street station ticket halls. As part of their contract they are required to carry out ground stabilisation through the use of injection grouting. The area requiring grouting is accessed from the C502 site and as a result we have been busy excavating a shaft and preparing the area for them. The grout that is to be injected behind the pile shaft wall first has to be piped into the grout box and this required the removal of a pile. The removal of the pile threw up a number of questions around the stability of the pile and ground given that it would effectively be suspended and relying on skin friction to stop it moving downwards and closing the gap. In addition and probably more importantly the pile would have no active pressure that it could use to resist the passive pressure of the soil and water behind the pile. To overcome this a reinforced concrete beam was cast into the piles to act as a whaler beam and fix the now free end of the pile. The task of organising the team to cut the pile and remove the concrete was given to the new boy (only once tea making duties were completed). After a period of scratching my head, I decided that the best means to attack the pile would be to get my old friend the diamond core drill and to stich cut the top and bottom of the pile and then to use the 3T excavator to break up the concrete in situ to then be removed in smaller pieces. First question to myself “where is the risk” and from what I could deduce it was more of a question of “where wasn’t the risk”. Working underground, confined space, removing a reinforced concrete pile section, pile failure, recent weather and ground conditions significant water ingress never mind the crushing injuries to persons operating in the shaft. As this was my first major task I felt a little military precision (oh the oxymoron) was required and not the John Moran approach of hitting everything with a stick. Following a detailed planning period during which the task was planned, risks assessed and planned out, reduced to acceptable levels and residual risk communicated, team briefs rehearsals completed the team was ready to go…. And it was then called off as C510 decided it wasn’t required.

In other news I have enclosed my fag packet calcs for those interested from the inclinometer drilling. While useful to plead my case with other engineers on site that the Heath Robinson clutch system was not sufficient I would not rely on them in court. Ultimately this proved to be a project contract and management issue as the contractor was summoned to prove calcs that proved his system worked and as he couldn’t the drilling was stopped and we have gone back out to tender for another contractor to complete the works.

Outside of work I have signed up to cycle London to Paris for some charity or other, more details to follow and I have been invited to sit on the board of a charity of a board called Engineers for Overseas development. The charity challenges young engineers to use their skills to design resource and construct a development projects overseas. The chairman felt that I might have a little bit of experience that would be useful…well you know I just might…pull up a sand bag and I’ll tell you all about it.