Application of Cone Penetration Test for Soil Layers Division

Soil layers division is a problem widely concerned in geotechnical engineering investigation. Aiming at solving this problem, drilling and standard penetration test (SPT) have been widely applied in engineering field, and abundant experience has been gained. Meanwhile, how to use cone penetration test (CPT) to solve the problem economically and effectively is of practical significance in engineering application. The application of static cone penetration curve in shallow soil layers division is studied based on the CPT curves acquired in a site located in south of Xuzhou, and the soil layers are divided by mechanics and named the soil by local experience. Comparing the soil layers division results acquired by this method and the results achieved by drilling hole, the division number of layers are the same. The depth of soil layers gained by this method is similar to that achieved by drilling hole when the soil is thick(the thickness is generally more than 1 m).For the interface depth of soil layers, the maximum and mean values of absolute error are 0.7 m and 0.24 m, and that of relative error are 0.54 and 0.16. From the comparison results, it is concluded that this synthesis method can reliably reveal the distribution of soil layers. Moreover, the features of the cone tip resistance-depth curves and the friction-resistance ratio-depth curves of four categories of soil layers were summarized, which offer a reference for soil layers division.