Abstract: As a regional special soil, the red clay has the characteristics of well-developed cracks and poor mechanical properties. The instability of the compositions in the red clay can be aggravated by the heavy metal (such as Cr³⁺) contaminations. To investigate the strength characteristics of Cr3+ polluted red clay samples, the relationships among the content of oxides (Al₂O₃, TiO₂, K₂O, etc.), mechanical properties and the content of Cr³⁺ in contaminated red clay were analyzed through the X-Ray Fluorescence (XRF), the direct shear and the consolidation tests. The variation of mechanical properties with the Cr³⁺ concentration is predicted based on the classification and regression tree (CART) method, and the effect of oxides on the strength of red clay was analyzed by data mining approach. The experimental results show that the shear strength and internal friction angle of the red clay decrease with the increasing of Cr³⁺ concentration, while the cohesion increases. The CART modeling shows that the oxides in the soil can affect the strength characteristics of the red clay.

Key words: Contaminated Red Clay, Oxide, Strength Characteristics, Classification and Regression Tree (CART) Method