Laboratory Assessment of the Equivalent Bearing Capacity of Clay Bed Improved with Stone Columns

Document Type : Original Article

Authors

Karim Bahari ¹

Sadreddini Seyyed Mohammad Ali ²

Mohammad Hadi Alizadeh elizei ³

¹ Department of Civil Engineering, Ro.C., Islamic Azad University, Roudenen, Iran.

² Department of Civil Engineering,Ir. C., Islamic Azad University , Eslamshahr, Iran.

³ Department of Civil Engineering, Ro. C., Islamic Azad University, Roudenen, Iran

10.22067/jfcei.2025.92285.1346

Abstract

Over the past few decades, construction on loose and problematic soils has posed significant challenges for geotechnical engineers. Among the methods to improve these soils, stone columns are notable, involving the replacement of weak soil portions with granular columns. This research investigates the enhancement of loose clay beds of classes CL and CH using sand columns.Unreinforced soil samples and those improved with a group of seven stone columns (30 mm diameter, arranged in a triangular pattern) were tested using a large-scale direct shear apparatus. Equivalent shear strength parameters were determined, and bearing capacity values were calculated. The shear tests employed the Fast method.

The effects of variables such as the type of surrounding soil, the number of layers in stone column construction, and the orientation of the limited stone columns (apex/base in triangular arrangement) on shear strength parameters and bearing capacity were evaluated. Results indicated that improving clay soils with stone columns significantly increased the bearing capacity of loose soils. The experimental findings showed that the execution method of stone columns greatly influences their load-bearing capacity. Moreover, improving CL clay soil with stone columns enhanced the bearing capacity more effectively than CH clay soil, indicating higher efficiency of this method in stiffer clay soils.

Keywords

Clayey bed

Sand column

Large-scale direct shear Test

Shear strength parameters

Bearing capacity

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