Authors:
R. P.A. Ball, D. J. Young, J. Isaacson, J. Champa, C. Gause
Rapid Excavation & Tunneling Conference (RETC), Las Vegas, USA, June 14-17, 2009
Abstract
The excavation of difficult soils by means of an Earth Pressure Balance Machine (EPBM) creates the potential for a reduced advance rate and increased downtime. EPBMs typically use soil conditioning to modify soil behavior to reduce abrasion, reduce cutterhead torque, control water, and ensure control of the spoil passing through the screw conveyor.
Recent research is presented concerning two difficult soils for EPBM tunneling, which are sticky soils and coarse grained soils with low fines content. Soil conditioning tests were performed on several samples of difficult soils, which provide insight into how different polymers and additives can modify soil behavior to improve the performance of EPBM mining. During testing, the use of high density slurry to augment soils with low fines content was investigated.
Results of investigation and a review of available literature is presented to help predict the potential for machine clogging and to help select useful soil conditioning agents in soils with low fines.
