Justification of a novel pipe-in-tunnel

摘要

As part of a major pipeline construction project, Laing O’Rourke had a requirement to install a section of pipelinenbeneath a river estuary. Due to a number of reasons it was not possible to negotiate the crossing using conventionalntechniques such as horizontal directional drilling (HDD) and an alternate method had to be sought. A feasibility studynwas undertaken and it was decided that a pipe-in-tunnel approach was the most viable. Due to constraints at the pointsnof entry and exit it was necessary to cut two vertical shafts, one on each river bank.