Liquefaction in silty soils―screening and remediation issues

摘要

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 (ν_(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 ν_(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 ν_(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.