Investigation for determining soft soil properties in pavement engineering

Two representative testing sites, K24 site and K25 site, were chosen along Tian-Xian expressway with soft soil subgrade. In-situ tests, such as Cone Penetration Tests (CPTs), Vane Tests (VTs), Pore-water Pressure Dissipation Tests (PPDTs) and Flat Dilatometer Tests (FDTs) were performed. Undisturbed soil samples obtained with borehole method using 100-millimeter diameter tin sampling device were collected for laboratory tests. Laboratory tests, such as Specific Gravity Tests, Density Tests, Natural Moisture Content Tests, Liquid Limit Tests and Plasticity Limit Tests, Consolidation Tests, High-stress Consolidation Tests and Unconfined Shear Tests, were performed. Comparisons between the results from in-situ tests and laboratory tests were made and the appropriate methods for the determination of the properties of soft soil in pavement engineering were put forward.