Engineering geology and the Thames barrier project

Abstract

The Thames Barrier, now under construction, is a structure containing movable gates which will prevent extra high tides flooding London. The majority of the piers are founded in chalk and a few at the northern end of the barrier will be set in the overlying Thanet Sand. The site investigation in these strata posed problems since the samples from boreholes are only of limited quality and the strata, being mostly under water, cannot be examined in situ. The investigation was carried out by boreholes using an extensive series of standard penetration tests and borehole permeability tests, together with tube samples for visual examination and classification testing. The detailed geological structure beneath the site was inferred from a geophysical survey and from a micropalaeontological investigation and was extended by visual examination of exposures of the strata in adjacent dry land sites. The results showed that there was a series of faults in the Chalk, but their presence did not appear to affect its engineering properties.