Deliberate Failure of Slurry Trench Excavations in Soft Clay

Abstract

The instrumentation used and the observations made on full scale field tests carried out in two slurry trench excavations in soft marine clay (at Vaterland, Oslo) are presented and discussed. The excavations were 1 m x 5 m and 1 m x 1.8 m in internal cross section and 20 m deep. The testing program was carefully planned to obtain information which could confirm the overall stability of the trenches using water instead of expensive special slurries. The instruments used included a precision settlement gauge, numerous settlement reference points and electrical piezometers, slope indicator casings and specially designed hydraulic gauges for instantaneous measurement of the inward movement of the vertical walls of the trenches. This project illustrates the importance of large-scale tests and instrumentation in Geotechnical Engineering.