7. Conclusion

The liquefaction of a soil layer expresses a loss of rigidity and resistance, accompanied by significant, even catastrophic, permanent deformations, endangering the site and structures concerned.

For the most part, these ruptures are caused by earthquakes in regions of medium to high seismicity. The most vulnerable soils are sandy, loose and saturated. Basic notions of soil mechanics help explain this behavior, which results from the accumulation of pore pressures in the soil layer over the course of cycles, with the consequent reduction in effective stresses.

Conventional monotonic or cyclic undrained laboratory tests point to the particular situation of loose, saturated sands, which are unstable and have low residual strength. This does not exempt moderately dense to dense sands, in which deformations accumulate over the course of cycles....