This study aims to investigate the effect of plastic fine content on the undrained monotonic behavior of sandy soils (mixtures of host sand and various plastic fine content from 0 to 25%), and in particular, their static liquefaction resistance (undrained shear strength). Illite Arvel is considered as a plastic fine to add to the host sand, the Fontainebleau sand. Binary mixture samples are reconstituted by using the moist tamping technique. A series of undrained triaxial tests were carried out to study the influence of different parameters, such as the fine content, the initial density index, the confining pressure, and the over-consolidation ratio (OCR) on the behavior of sandy soil mixture. Based on the results acquired from these tests, the liquefaction susceptibility of the sandy soil is discussed by using Chinese criteria.

Liquefaction is of major concern in many countries subjected to seismic hazard. In practice, prediction of liquefaction is performed using simplified methods based on in situ tests such as the standard penetration test (SPT) or the cone penetration test (CPT). For some applications such as large projects (tunnels, high rise buildings), the Ménard pressuremeter is preferred as it provides a well-established method for foundation design. However, no simplified method to evaluate liquefaction potential has been fully developed for the pressuremeter. Based on pressuremeter calibration chamber and field tests on sands, a chart is proposed for estimating the liquefaction susceptibility of saturated sands. In addition, a method to correct the measured limit pressure from pressuremeter tests is also proposed for tests in sands with fines content. The method was evaluated using extensive data obtained from tests performed in a calibration chamber using clean sand and sand with fines content against 45 pressuremeter tests performed in situ in various soil conditions. Based on these tests, a relationship was obtained between the field data and the chart developed from the calibration chamber tests. The paper also provides suggestions to correct the limit pressure to account for the fines content.