Trenchless Technology

Abstract

Trenchless technologies cover a wide range of methods of installing new cables, pipes, ducts and small-diameter tunnels in the ground without open excavation between the start point and end point. For the smaller sizes, the installed structure is of circular cross-section, but for larger sizes in suitable ground conditions non-circular sections may be possible. The larger-size installations at substantial cover depth provide an alternative to conventional tunneling methods, while at shallow depths trenchless technologies usually compete with installation in open trench. For small-diameter pipes, techniques such as microtunneling and directional drilling provide the only economic methods of installation at depth. Trenchless technologies also include various methods of on-line replacement and renovation of existing pipes and ducts. A useful summary of the methods available is provided in Trenchless Technology Guidelines, produced by the International Society for Trenchless Technology (ISTT).