Abstract
The presented paper aim is to validate the application of the log piling method as a safe, cost-effective and environmentally friendly densification method for reducing the risk in terms of soil liquefaction during seismic excitation. Recent applications of the technique in Japan assume that log piles shall penetrate the whole or most of the liquefiable soil layer in order to prevent damage during earthquakes. However, such mindset might lead to economically ineffective solutions as in some cases improvement depth might become unreasonably great. Previous studies and observations prove that shallow ground improvement significantly influences the seismic response of the “liquefiable soil – improved zone – superstructure” system in a favorable way – quantitively represented by the reduction of liquefaction-induced total settlement and penetration settlement. The purpose of the paper is to demonstrate the outcome of small and medium-scale 1-g shaking table tests for the sake of providing practical guidelines for setting optimum dimensions of the modified ground zone. In order to do so, first series of tests (small-scale) focus on an extended parametric study which delivers conclusions regarding improvement width, center-to-center piles distance and improvement depth to liquefiable layer thickness ratio, whereas the second one (medium-scale) aims to give a suggestion for the minimum absolute value of the piles’ length. This paper allows engineers in practice to follow a full step-by-step procedure for adopting the log-piling method as liquefaction mitigation countermeasure for small residential buildings.
