The long-term performance of permanent ground anchors forming part of the Thames Barrier Project

This paper describes monitoring work undertaken on a site where permanent ground anchors had been installed in 1979 to support a new sheet piled river wall, on the south bank of the Thames.

In 1999/2000 the site was redeveloped for residential use. The building loads were supported on piled foundations close to, and in places threaded through, the permanent anchors. The condition and residual loads in the anchors were checked before, during and after the foundation construction works. At the same time, the response of the anchored river wall was checked by optical survey techniques to confirm that the new works were not adversely affecting the wall: particularly by any disturbance to the integrity or performance of the ground anchors.

The monitoring demonstrated that the anchored wall behaved in a resilient, robust and controllable manner, even when isolated anchors were destroyed by the piling works.

Matters of concern beyond the particular project are also highlighted. These include a general lack of maintenance and inspection of such anchored structures, and the disturbing fact that as-built and construction records, even of such relatively young and vital structures, appear to have rapidly been lost.

• Introduction

• Background

• Preliminary load/condition checks

• Construction load checks

• Wall movements

• Load changes compared with wall movements

• Anchor failures

• Summary

• Conclusions

• References