Even the simplest activity can be complicated when it has to be carried in hyperbaric conditions.
We have participated in EPB projects where cutterhead maintenance had to be done in hyperbaric due to the ground constraints.
There, we have learnt that methodology, schedule, organization, and mitigation plans, are mandatory to obtain good results. Otherwise, it can become a dangerous waste.
Usually, and depending of the local regulation, the hyperbaric works can only be done by qualified staff, in possession of permission from authorities. It’s common to contract divers, who have all this kind of formation.
First step of any hyperbaric operation is to check the condition of the front. The bentonite cake has to create a membrane which seals the ground. Air consumption has to be evaluated before enter in the chamber.
The level of earth in the chamber depends of each kind of ground and working pressure.
Extreme caution has to be taken always while working in the chamber, and even more if it’s in hyperbaric environement.
To facilitate communication and reporting, it’s useful to use video camera and recorder.
The time of each intervention is very limited, so everything has to be clearly defined before start.When the purpose is just to inspect the wear, it’s necessary to focus just in the important tools.
The high temperature of the chamber, the dirty of ground plus bentonite, and the elevated level of moisture, produce a difficult and exhausting environment to work. Some members of the hyperbaric team are required just to assist the others.