OWNER:
East Sussex County Council
ENGINEER:
Mott MacDonald
GENERAL CONTRACTOR:
Hochtief and Taylor Woodrow (Joint Venture)
MAIN FIGURES:
13,000 Controlled Modulus Columns (CMC), 360-400mm diameter to depths of 4-16m
4,200 Vertical Drains to depths of 10m
Project Details
The project of Bexhill to Hastings link road consists of building a short single carriageway road of 5.6km to reduce traffic congestion on the main A259 and other local roads. The ground improvement solution has been chosen for this project in order to control the problems of settlements as well as with slope stability problems. The improved area is 1.6km long of fill and cuttings for the new roadway, and a total of 92,000 m².
Ground Conditions
Variable thickness of 0 to 14m maximum: Alluviums (with some presence of Peat)
Beneath: Ashdown Beds (weathered Siltstone and sandstone mainly)
Solution
A Controlled Modulus Column (CMC) solution with Vertical Drains has been chosen beneath road and landscape areas. The CMC diameter varies between 360 and 400mm. The CMC’s are unreinforced below the main embankments, however they are reinforced with either reinforcement cages or a single steel bars on the edge rows of the embankment, to overcome any lateral loading. The concrete used is a C20/25 S4 10mm or a C25/30, depending on the area. The prefabricated vertical drains are used to accelerate the consolidation of the alluvium under the lateral landscape embankments when CMC are not necessary.
