Comparative investigation of the deformation behavior of jet grout columns using finite element analysis and field load tests

In this thesis, axial static load test results of Jet-Grout columns constructed in seven different regions within Afyonkarahisar Province were evaluated and compared with numerical analyses performed using the PLAXIS finite element software. The numerical models were developed based on site-specific soil profiles and actual loading stages applied during field tests. The bearing capacity and settlement behavior of Jet-Grout columns were investigated under 100% and 150% loading levels. Field test results indicated that Jet-Grout columns exhibited low settlement values and stable behavior without sudden failure under both loading conditions. Numerical analyses generally produced higher settlement values than field measurements, mainly due to the system-level modeling approach in PLAXIS, which considers the foundation plate, column group effects, surrounding soil behavior, and load distribution mechanisms. Despite these differences, numerical results provided conservative and safe estimations from an engineering perspective. Comparative analyses showed that the agreement between field measurements and numerical results improved at higher load levels, indicating more homogeneous and predictable soil–column interaction. In order to obtain more realistic numerical predictions, an empirical load-dependent calibration approach was proposed based on the ratio of field and numerical settlement values. The proposed calibration improves the consistency between numerical analyses and field behavior, demonstrating that finite element modeling is a reliable and practical tool for the design and performance evaluation of Jet-Grout columns. 2026, xi + 87 pages Keywords: Soil improvement, Jet-Grout column, Axial static load test, Settlement behavior, Finite element method