Improvement of an Undisturbed Peat Soil with Jet Grout Columns: Physical and Numerical Modeling

The bearing capacity of the composite-formed soil, such as grouted peat soil, is a crucial design parameter that can be improved by employing jet grout columns (JGCs). The coupling effect of the requirement of new industrial sites and reduction in the suitable regions for construction requires research on improving the bearing capacity of abundantly available peat soils. Despite routinely reported studies on peat soil, improvement studies basically took upon the disturbed soil samples. Research on the sample collecting techniques or experiments on undisturbed peat soil has not been conducted intensively. This study uses a domestic jet grout device to compare features of the undisturbed peat soils at the laboratory using axial loading tests. While samples were collected undisturbedly using specially designed steel boxes, the peat soil within the steel boxes was improved by jet grout columns. Additionally, PLAXIS 3D simulations were used to estimate the behavior of the improved soil. Results showed that the bearing capacity of the soil increased 4 times for square foundations (2 x 2 JGC) and 4.5 times for strip foundations (3 x 1 JGC) compared to the unimproved organic soil.