M351 Strasbourg, Grand-Est – France

Project Overview

During a multimodal development scheme to create a dedicated public transport lane on the M351, construction of a stormwater management basin was required. A 5m high, 165m long 65° cut-face slope would be needed to create space for the construction of the walls and foundations of the structure. A soil nail solution had been suggested, however, earth anchors would be a quicker and more economical solution.

Solution

Suitability tests showed excellent performance, with the design specifying 760 Percussion Driven Earth Anchors (PDEA^®) along the length to stabilise the slope. Each anchor was driven perpendicular to the slope face using a tracked excavator to a depth of 5m, before being loadlocked at a working load of 30kN, which was recorded with the anchor number and date. Being immediately serviceable the anchors provided instant stabilisation of the slope, allowing work to continue without wait times. To reduce the time required, three teams worked on this project simultaneously, the first team excavating, the second driving anchors, and the final team load locking anchors. Following completion, the slope was backfilled against the wall of the basin.

By using the Platipus solution only 23.7 tonnes of Embodied Carbon was emitted. Comparatively, the originally proposed soil nail solution would have emitted 56.2 tonnes of Embodied Carbon. An overall saving of 32.5 tonnes of C02e, or 58%, was achieved by using the Platipus Low Carbon Anchoring Solution (LCAS^®).