CUED Publications database

Permeability of aged grout around tunnels in London

Laver, RG and Soga, K and Wright, P and Jefferis, S (2013) Permeability of aged grout around tunnels in London. Geotechnique, 63. pp. 651-660. ISSN 0016-8505

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Abstract

Prediction of the long-term settlement of clay soils over tunnels requires a knowledge of the permeability of the soil and of the tunnel lining; however, determination of the lining permeability in the field is difficult. An important contributor to this problem is the lack of knowledge concerning the permeability of the grout between the lining and the soil. This paper presents the results of tests to characterise the properties of grout samples from London Underground tunnels, investigating permeability, porosity, micro structure and composition. The tests revealed that the newer grout was impermeable relative to the surrounding clay. However, the older samples showed much greater permeabilities and an altered grout composition, suggesting that degradation had taken place. Exposure to groundwater appeared to have caused carbonation and sulfate reaction. The combination of chemical reaction and leaching of cementitious and degradation products appears to have made these grouts more permeable, so that the grout could act as a drainage path rather than a barrier. This challenges the typical assumption that the grout acts as an impermeable barrier.

Item Type: Article
Uncontrolled Keywords: Grouting Permeability Tunnels
Subjects: UNSPECIFIED
Divisions: Div D > Geotechnical and Environmental
Depositing User: Cron Job
Date Deposited: 07 Mar 2014 11:46
Last Modified: 08 Dec 2014 02:18
DOI: 10.1680/geot.11.P.125