GIS – 06 September, 2018: A site visit, at the embankment failure site along the Motorway M3-Terre Rouge-Verdun, was conducted yesterday by the Minister of Public Infrastructure and Land Transport, Mr Nandcoomar Bodha. The aim was to take stock of the progress achieved with regards to the ongoing repair works.
In a statement, Minister Bodha underlined that the works have reached an important phase and spoke of the necessity for the population to be apprised of the complexity of the site. This will help one and all to better understand the causes behind the failed project and the complex repair works it entails, he pointed out.
The Minister indicated that geotechnical investigations and tests were carried out over the whole stretch of the road so as to establish the exact nature of the failure and to come up with appropriate reconstruction designs for permanent remedial works. It was established that the embankment failure was due to the inadequate bearing capacity of the underlying layer, he stated. The road, he remarked, was built on a foundation that was not solid enough as the ground underlying the embankment had poor properties.
Furthermore, Minister Bodha stated that it was decided that one major phase of the repair works would comprise carrying out slope stabilisation works on the site of landslide zones. This decision was taken following consultations with various international experts including Professor Jean-Pierre Magnan, from the French Institute of Science and Technology for Transport, Deployment and Networks.
Speaking about the slope stabilisation works, the Minister explained that this process involved the following: removal of 14 metres of upper layer soil having poor properties; and, reconstruction of the fill which will include the reinforcing of the slope by complementary rigid vertical and horizontal piles to block any further movement of the embankment and underlying ground. In addition, he said, two rows of 180 piles of one meter in diameter each, will be inserted in a depth of 20-25m in the ground, and 2.5 meters away from each. The slope will be stabilised by nailing it to the adjacent land which is more solid.
Moreover, Minister Bodha indicated that sophisticated equipment will be used to carry out the repair works in a timely and effective manner under the supervision of the Centre d’études et d’expertise sur les risques, l'environnement, la mobilité et l’aménagement (CEREMA). The project, he emphasised, is abiding to the three governing principles namely: respecting technical specificities, procurement and budget.
The installation of the piles and filling works are due to start in two weeks’ time and expected to be completed by mid-December.
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