The cost of reinstating slip failures on the U.K. trunk road and motorway system represents substantial expenditure for the Department of Transport (DOT). This report provides details of the use of grout injection to repair a shallow translational slide on an embankment on the A45 Cambridge Northern By-pass. This embankment was seven metres high, had side slopes of 1:2, and was formed from over-consolidated Gault Clay. The total cost of the repair was about 870 per metre run of embankment. The estimated costs of the shallow grouting works at this site was about 450 per metre run, about 50% more expensive than the costs of repairs using geotextile reinforcement. However, grout injection can be used without the need for excavating into unstable slopes and so may find some application in the repair of highway earthworks. No movements of the road pavement were measured during grouting operations, and no movements of the slope or pavement have been recorded in the 18 months or so following the end of site works. Thus the grouting operations seem to have stabilised the slope of the embankment.

Want to know more about this project?