Abstract: The composition， microstructure and mechanical indexes of the soil can be changed by acid solution. Through the 0 (water)，1%，4%，8%，12% concentration of hydrochloric acid solution soak tests， the silt polluted by acid solution was simulated. The variability of resisting shear and compression index about the corroded silt was gained by indoor consolidated quick shear test and quick consolidation test. The results show that the cohesive force is increased， the internal friction angle and the compression modulus are decreased， and the compression coefficient and the compression index are increased. The reason for the corroded silt property variation about material composition and microstructure was explained by the results of the chemical composition analysis and scanning electron microscope. The relevant indexes of bearing capacity and slop stability will be changed consequentially because of the variations about resisting shear and compression ability. Therefore， the above variable conditions should be considered in the survey design and analysis of the accident causes for the silt region with acid pollution hazard.

Key words: contaminated soil, resisting shear and compression index, microstructure, mineral composition, mechanism of action