Patent ID: 7033114

Claim:
A method of reinforcing a cylindrical underground pipeline, comprising the steps of: laying an excavation coffer on the ground above the pipeline, front and rear faces of the coffer being placed transversely to the pipeline, each of said front and rear faces having along a lower edge thereof an indentation of a shape adapted to a cylindrical shape of the pipeline; driving the coffer into the ground substantially until said indentations are brought up against the pipeline, and removing soil material between the front and rear faces of the coffer to provide access to an upper part of a wall of the pipeline; further removing soil material under the pipeline from the inside of the coffer; installing at least one reinforcement around the pipeline in an interval between the front and rear faces of the coffer; and wherein the step of driving the excavation coffer into the ground comprises a first phase, wherein linear guides are driven vertically into the ground on either side of the pipeline, and a second phase, wherein the front and rear faces of the coffer are slid along said linear guides.