An original and innovative solution for the renovation of valleys in the city of Grasse / Cote d'Azur, France by a geosynthetic clay liner

摘要

Two valleys in the centre of Grasse, a city situated in the south of France near the coastal town of Nice, regularly suffers from ground collapse and general instability. These problems directly endanger buildings, mainly houses and hotels. Site investigations identified the problem was due to the underlying geology, specifically the presence of alternating beds of gypsum and clay. this situation, coupled with important slopes, was the cause of multiple collapses (dissolution of the gypsum by rain and sewage water), slope failures and erosion by running water of several streams. The required solution is a combination of traditional stabilisation by wooden dams with needle punched geosynthetic clay liners providing the sealing element. Three growing seasons after installation shows that the GCL is contributing in a dynamic and efficient manner to the natural and long term renovation of an area with complex problems.