Slope Stability and Embankment Assessment

KEY FACTS

Who

Confidential

What

Slope Stability and Embankment Assessment

Where

Salford, Greater Manchester

How long

3 days

Outcome

Reprofiling of an embankment that would not impact the M602 Highways England asset.

THE PROJECT

Our geotechnical team was commissioned to assess the impact of a proposed new-build apartment block, which would involve cutting away some of the southern embankment of a site to create a developable platform. The embankment had formerly supported a railway line and currently forms the southern boundary to the M602 motorway. Highways England required confirmation that the reprofiling of the embankment would not impact upon the M602 motorway.

A range of retaining solutions were proposed, to stabilise the re-profiled embankment. These comprised of gabions, contiguous piles and kingposts along sections of the embankment at various heights of cut. We carried out ground investigations to determine the ground conditions of the southern area of the embankment.

 

THE SOLUTION

Our approach included geotechnical investigation with laboratory testing. This allowed modelling of the slope and run analysis on the stability of the slope in existing conditions, during temporary works and with toe remediation.

The ground investigation comprised a range of window sample drilling using a modular rig, cable percussive drilling and Dynamic Cone Penetrometer tests at selected locations along the embankment. A range of geotechnical testing, including determination of Atterberg limits, bulk density and triaxial testing, was carried out for determining the design parameters in the slope stability risk assessment.

Analysis was undertaken using proprietary slope stability software. A Ground Investigation Report (GIR) and Geotechnical Design Report (GDR) were completed in line with the Highways England Design Manual for Roads and Bridges (CD622 Managing Geotechnical Risk).

THE BENEFIT

The former railway embankment was reprofiled to accommodate the apartment block layout utilising the various retaining wall solutions, with no impact to the M602 motorway.