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Modified Bentonite Slurries for Slurry Shields in Highly Permeable Soils

Abstract:

The slurry shield method is a widely-used tunneling method in soft soils. Bentonite suspensions are used to stabilize the working face by building up support pressure. In coarse, highly permeable soils, the suspension penetrates the ground and the required support pressure cannot be reached. Improvements of the commonly used bentonite suspensions can be achieved by modifying the bentonite slurries. In the laboratory, the effects of the additives polymer, sand and vermiculite were studied. A suspension containing these three additives in well defined proportions enables the formation of a tight membrane and filter cake even in highly permeable soils. Proof of the concept was obtained by the successful application of the modified bentonite suspension at the Hermetschloo Gallery in Switzerland.

Authors:

Fritz, Pit and Hermanns Stengele, Rita and Heinz, Anja

Index Terms:

Hydroshield; Suspension; laboratory test; slurry walls; Bentonite; rock; TunnelingGroup; Soil; SoilGroup; Fritz, Pit; Heinz, Anja; Hermanns Stengele, Rita

Further Information:

Date published: 2002