Seismic Cone Penetration Test Assessment of Vibratory Probe Compaction for Liquefaction Mitigation

Abstract

Soil liquefaction is a major concern of highway foundation failure at sites of loose silt or sand. A self-developed deep vibratory probe compaction equipment with frequency-variable piling vibrator is adopted to insert a probe with cross section into the soil which needs to be densified. In situ seismic piezocone tests (SCPTu) were performed and the soundings of cone tip resistance (q t ), sleeve friction (f s ), pore pressure (u 2 ), and shear wave velocity (V s ) were recorded before and after soil densification, with vibratory probe at a 15m-thick silt deposit at Suqian-Xinyi Expressway liquefiable site in China. Maximum dynamic shear moduli (G max ) evaluated from SCPTu data before and after densification were compared in order to assess the effect of ground improvement. In addition, the liquefaction potential was also estimated. Seismic piezocone test exhibited a significant increase in maximum dynamic shear modulus (G max ) and shear wave velocity (Vs) due to soil densification. It is concluded that the soil was densified to the level of resisting potential liquefaction and SCPTu is an effective way to evaluate the effect of ground improvement.