Physical and Mechanical Properties of Turfy Soils under Confining and Axial Pressure Increases Stress Paths in Jilin Province, Northeast China

In recent years, highways have been built rapidly in China’s turfy swamp areas to accommodate economic development. Turfy soil is a type of special soil with high humus and incompletely decomposed plant contents, so its properties are complex and unique. Both the axial and confining pressures of turfy soil increase during embankment filling. Therefore, in this study, three soil tests for analysing the decomposition degree, organic matter content, and triaxial compression under confining and axial pressure increases stress paths were performed to achieve insights into the stress-strain properties of turfy soil. The volumetric and deviatoric strains of turfy soil were summarised to reveal the inner mechanisms of turfy soil, culminating in the establishment of a constitutive model for turfy soil. The results of the constitutive model were compared with the experimental test results to verify the accuracy of the constitutive model. The results showed that the stress-strain and strength of turfy soil are closely related to the organic matter content and decomposition degree. The calculated stress and strain results are also consistent with the experimental results, indicating that this constitutive model can be used to better indicate the original deformation state and strength characteristics of the turfy soil.