Liquefaction in silty soils—screening and remediation issues

Current techniques for liquefaction screening, ground modification for liquefaction mitigation, and post-improvement verification rely on knowledge gained from extensive research on clean sands, field observations of liquefied ground, and judicial correlation of normalized penetration resistance [( N 1) 60, q c1N] or shear wave velocity ( v s1) data with field liquefaction observations. Uncertainties prevail on the direct extrapolation of such techniques for silty soil sites. This paper examines laboratory data on liquefaction resistance, strength, and v s1 of sands and silty soils using grain contact density as the basis. Effect of silt content on cyclic resistance, strength, m v, and c v is examined in this light. Rational insights on effects of silt content on the current screening techniques based on ( N 1) 60, q c1N, and v s1 to silty soils are offered. Recent advances and modifications to the traditional densification, drainage, and permeation grouting techniques to make them viable for silty soils are discussed.