Liquidity index of the Lublin loess as a function of cone resistance qc from CPTU test

The paper presents the results of the calibration of an interpretive formula for the determination of I_L based on cone resistance q_c for loess soils. The studies were carried out on characteristic soils that occur in the Lublin region. For this purpose, three CPTU static soundings were selected in which a representative soil profile with a total length of 21 m was extracted. Boreholes were drilled in close vicinity, at distances ranging within 1.0 m, and samples for laboratory testing were collected at intervals of 0.25 m. A total of 86 samples were tested and the liquidity index was determined. The I_L values specified in the laboratory were paired with the cone resistances q_c averaged over the depth range corresponding to the sampling. The q_c/p_a - I_L distribution was then analysed and a formula correlating both parameters was derived. The cone resistance depends not only on water content but also on a number of other factors, therefore, the estimation of I_L from CPTU tests should be regarded as an approximation, while an accurate identification of the subsoil requires further investigations. Nevertheless, such information provides valuable knowledge in the initial stages of subsoil recognition, e.g. during design work.