Construction of a deep shaft for Crossrail

Abstract

This is the accepted version of the paper.This version of the publication may differ from the final published version. that support Moorhouse and the presence of these foundations placed tight constraints on acceptable ground movements associated with construction of the shaft. The depth of the shaft is such that it penetrates through stiff London Clay and is founded at the bottom of the Lambeth Group. The paper describes the contingency measures to deal with potentially difficult ground conditions including the water bearing layers of the Lambeth Permanent repository linkGroup. The construction processes included a complex temporary works dewatering system around the shaft with the option to carry out additional dewatering from within the shaft during excavation. Provision was also made for radial grouting to "restress" the ground, to prevent long-term settlement of the Moorhouse piles, should the need arise. The success of the project was due, in no small part, to the detailed planning and consideration of contingency measures to deal with perceived risk.

Subsurface ground movements due to circular shaft construction

“…Only one in two inclinometer measurements reported by McNamara et al (2008) and Wong & Kaiser (1988) are also utilised in this study. This is because the other inclinometer readings were either affected by existing piles (McNamara et al, 2008) or not fully reported; possibly due to poor accuracy (Wong & Kaiser, 1988) and hence these are not used.…”

“…Figure 8 presents subsurface horizontal soil movements in the considered shafts, reported by McNamara et al (2008) and Wong & Kaiser (1988), together with results from two centrifuge tests. Horizontal movement at depth and at a distance from the wall, ℎ , is normalised against the maximum horizontal displacement at that radial distance, ℎ and the depth is normalised against .…”

Numerical modelling of the Ivens shaft construction in Lisbon, Portugal

“…The increasing use of underground space in metropolitan areas has led to an increase in shaft construction, since they provide the most direct access route to the subsoil (McNamara et al, 2008;Schwamb & Soga, 2015). The term shaft is typically employed to define a geotechnical structure which has a depth larger than its width (Muramatsu & Abe, 1996) and that connects the ground surface to the underground.…”