Horizontal soil movements in excavations protected by sheet-pile cut-offs

摘要

This paper reports on the measurements taken of horizontal movement during the excavation of a 5-m deep and 7-m wide trench created for the installation of 5 X 3 metre concrete caissons to channel water from two streams running in the vicinity. Thealluvial deposit in the stream at the excavation site consists of gravel with a sufficiently thick clayey matrix to enable a sheet-pile cut-off wall to be sunk over three metres down. The construction process used consisted of driving the sheet pile in by vibration to a depth of over 3 m beneath the bottom of the excavation, digging an 0.60-m pit to fix bracing at the head of the cut-off and excavating down to 5 metres. Once the caissons were in place, the trench was refilled and the sheet pile removed.The excavation site was on an urban street, making it necessary to assess the extent and scale of any possible horizontal movement, in order to take the appropriate steps to prevent problems occurring in adjoining buildings. Measurements were taken during the excavation work of the horizontal movement occurring. The paper reports on the results.