Determination of the relevant soil stratigraphy is of the paramount importance for any geotechnical analysis. The cone penetration test (CPT) is the cost-effective, rapid, continuous, and reliable testing method for assessing soil layering and estimating in-situ mechanical properties of soil, and as such is especially useful for subsoil investigations along linear infrastructure networks, such as roads, highways, or railways. The design soil profile can be effectively determined using the CPT-based soil behaviour type (SBT) classification system. However, the soil profile consists of layers of various thickness and some layers can be only a few centimetres thick. Because the cone needs to penetrate to a certain depth to develop the cone resistance and to identify the presence of another layer, thin layers of soil cannot be properly detected. The soil layering algorithm, presented in this paper, merges these thin layers into the adjacent layers and thus overcomes the unreliable determination of the thin layers. The implementation of the proposed algorithm is demonstrated using a CPT carried out on the embankment test-site in north Croatia.

CPT, soil layering, vertical variability, SBT soil classification