Contiguous and secant piled walls

Contiguous and secant piled walls can be used to form embedded retaining walls, for example, to construct tanks, shafts, tunnel portals, road/rail cuttings, basement excavations, cut and cover tunnels and other forms of underground structures. They are commonly adopted where alternative methods cannot be successfully implemented because of the nature of the ground or performance requirements. In common with diaphragm walls, the economics of contiguous and secant piled walls become increasingly attractive when they form part of the permanent works. This chapter includes a description of common uses of contiguous and secant walls and their method of construction (including aspects of additional temporary works required to facilitate construction), a summary of typical construction details which can aid construction of a high-quality finished product, and a description of common design approaches and design considerations.