Investigating the dynamic response of deep mixing columns and gravel columns in liquefiable layer with different thickness

Document Type : Research Article

Authors

1 Associate Professor, Department of Civil Engineering, Urmia University

2 Department of Civil Engineering, Urmia University, Urmia, Iran

Abstract

Liquefaction is one of the most devastating Geotechnical phenomena that severely damages vital structures and lifelines. accurate understanding of the dynamic response of the site prone to liquefaction and improved with different modern methods and comparing it with the unimproved site improves the ability of engineers to choose the appropriate improvement method. Before construction, it is necessary to solve the geotechnical problem. Among the methods of land improvement to deal with liquefaction, gravel columns and deep mixing columns can be mentioned. In this study, the results of 1g shaking table tests by flexible box on the foundation located on the liquefiable ground surface and reinforced with aforementioned techniques have been investigated. The dynamic responses of the reinforced ground in different thicknesses of the liquefiable layer and the different frequency of the input movement have been investigated based on stress-strain behavior, secant shear modulus of the soil and excess pore water pressure versus shear strain. The results of the tests show that the thickness of the liquefiable layer has a considerable effect on the dynamic responses of the soil, including the shear behavior and the shear modulus of the soil. By increasing the thickness of the liquefiable layer, the values of secant shear modulus and shear strain of the improved mass decrease and increase respectively. Also, the dynamic performance of deep mixing columns in thicker layers is more suitable compared to gravel columns, and at lower thicknesses, the dynamic behavior of gravel columns approaches that of deep mixing columns.

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