CUED Publications database

Soil conditioning under London

Borghi, FX and Mair, RJ (2006) Soil conditioning under London. Tunnels and Tunnelling International. pp. 18-20. ISSN 0041-414X

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The CTRL Contract 220 covered 7.5km twin-bore tunnels excavated between late 2002 and early 2004 from Stratford Box to St Pancras station in Central London. To ensure efficient machine operation as well as the transport and disposal of soil, soil conditioning treatments were applied. Specifically, the foam injection ratio (FIR) and the polymer injection ratio (PIR) (injected volume of foam and polymer solution expressed as a percentage of the excavated soil volume) were employed. It was found that carefully selected soil conditioning allowed chamber pressures of 200kPa or more to be accurately controlled in the stiff London Clay and to an extent, in the very stiff clays of the Lambeth Group. Average FIRs of 50% and PIRs of 7 and 9% were used in the Thanet Sand and in the Lambeth Group Clays. In contrast, much lower quantities of foam were used in the London Clay.

Item Type: Article
Divisions: Div D > Geotechnical and Environmental
Depositing User: Cron Job
Date Deposited: 17 Jul 2017 19:27
Last Modified: 18 Aug 2020 11:36