Treatment of Liquefiable Soils by the Ballasted Column Technique: Case of Martil River Bridge in the North of Morocco

Abstract

The seismic activity in northern Morocco is largely due to an intense tectonic activity Plio-Quaternary and current generated by the approach of the two lithospheric plates Africa-Eurasia. Certainly, the liquefaction of soils is a phenomenon that presents a potential risk and a major challenge for the construction of foundations of engineering structures. The objective of this work is the realization of test plates to decide on adequate treatment in a soil liquefiable. For our case during the construction of a double bridge on a liquefiable soil and in a seismic zone, we were confronted with two technical problems, on the one hand the choice of the method of treatment of the soil in place and on the other hand the verification of this improvement by the results of the CPT tests (Cone Penetration Test) carried out before and after the densification of the soil. Many types of liquefaction remediation methods have been developed. However, for our case, the results indicate the effectiveness of the vibrocompaction method in improving the in-place soil compared to the dry method in eliminating the risk of soil liquefaction. It should be noted that the wet columns were lowered to 22m/TN, and the dry columns were stopped at varying depths between 2 and 14m/TN, and the results of the CPT (Cone Penetration Test) confirm the effectiveness of vibrocompaction and that the bridge foundations are protected against the phenomenon of soil liquefaction.