Biocalcification for slope reinforcement against internal erosion : results of experimental laboratory works and presentation of real case applications.

Soletanche Bachy has developed and patented an innovative soil reinforcement method based on a natural biological process leading to the formation of calcite in situ, called Biocalcis®. This process is adapted for being applied in different soils and hydraulic conditions, including on hydraulic structures where continuous hydraulic flow is encountered. The mitigation of internal erosion is necessary to prevent damages on the infrastructure or the slope due to mechanical failures. Biocalcis treatment presents the advantage not to significantly change the overall permeability of the treated area and therefore avoid the risk of material sealing and waterproofing. Results obtained at sample scale during the frame of BOREAL project will be presented, during which four different erosion test devices have been used: Contact Erosion Test, Hole Erosion Test, Jet Erosion Test and Suffusion test. The resistance of untreated and treated soils will be detailed. The treated soils were obtained after injection of biocalcification in laboratory columns or inside large physical models using real site materials. All the test results indicate a strong increase of erosion resistance from a small percentage of added calcite (~2- 4%) that is easily achievable on real sites with the process. The presentation will also show examples of applications on real sites using different implementation methods. Environmental and durability aspects will also be addressed.