Recent developments of soil improvement methods for seismic liquefaction mitigation

Although traditional methods of liquefaction mitigation have been widely applied in engineering practice, some prominent problems remain such as limits on the size of the treated areas, disturbance of existing structures sensitive to deformation or vibration, and environmental impact. In terms of liquefaction mitigation, some relatively new concepts have been proposed such as passive site remediation, microbial geotechnology, and induced partial saturation, and new methods have been developed based on these concepts. In this paper, as a reference to engineers and researchers involved in solving the problems faced by our developing society, we review the recent development of soil improvement methods for liquefaction mitigation. We present methods of liquefaction mitigation and suggest their classification into three types. We review, for the first time, the engineering problems and research trends of liquefaction mitigation and discuss several typical new methods such as colloidal silica grouting, bentonite suspension grouting, biocementation, air injection, biogas, and mitigation using tire chips. Finally, the applicability of these new methods in solving the above problems is discussed, and future research orientations are pointed out.