Numerical studies on the efficiency of jet grout columns in liquefaction mitigation

Liquefaction, one of the main research topics of geotechnical engineering, is one of the major causes of structural damage caused by dynamic loads. In this study, the contribution of jet grout columns to bearing capacity, settlement problems and liquefaction was tried to be determined by numerical investigations. The results of the ground studies conducted in the field where the Transformer Assembly-Dismantling Building is located in Kocaeli were evaluated. The local soil consists of silty sand. The bearing capacity, settlement and liquefaction potential were evaluated using different methods based on the data of the drillings, the index properties of the research pits and soils. The liquefaction risk of the ground in the work isn't the acceptable value. In the study area where bearing capacity, settlement and liquefaction problems were determined according to the determined soil properties, it was investigated by analytical and numerical methods whether the problems in question disappeared after the production of the jet grout columns selected as an improvement method. To investigate the effectiveness of jet grout columns in preventing liquefaction through a field study, MIDAS GTS NX performed numerical analyses using the UBCSAND constitutive model. One of the most important features of the model is that it is an elastoplastic model that can examine the pore water pressure depending on time. The shear stresses, shear deformations, and changes in excess pore pressure ratios in the liquefied soil during the earthquake were examined by considering different column strength ratios and area ratios. The results were evaluated and interpreted. As a result, it has been shown that although jet-grout columns are more rigid and subjected to greater shear stress, they do not significantly reduce shear deformations and excess pore water pressures in liquefiable soil.