Abstract: In order to predict and evaluate the water repellency and engineering geological properties of weathered soil under the influence of mining， the relationship between fractal dimension of grain size and consolidation was studied. Based on the fractal theory， the fractal dimension of ten samples from weathered residual soil of Sinian quartz sandstone in Sijiaying Iron Mine was calculated to regressively analyze the correlation among void ratio， porosity， grain size fractal， fine grain content and compression coefficient. By calculation， it was found that the fractal dimension of weathered residual soil of quartz sandstone in Sijiaying Iron Mine ranges from 2.603 68 to 2.733 76. With the use of Curve Fitting Tool in MATLAB， the binary quadratic regression relationship among fractal dimension， fine particle content and compression coefficient was obtained. The fractal dimension of grain size has a certain guiding significance for analyzing soil consolidation.

Key words: Weathered soil, Fractal dimension, Fines content, Void ratio, Coefficient of compressibility, Consolidation