Effects of Variable Proportions of Concrete Fragments on Urban Soil Moisture Transport: An Experimental and Simulation Study

Abstract

In order to investigate the effects of typical anthropogenic concrete fragments on moisture infiltration and evaporation in urban soils, the effects of typical anthropogenic concrete fragments on wetting peak transport distance, cumulative infiltration, cumulative evaporation, evaporation rate, and soil profile moisture at four levels (0, 5%, 10%, and 20%) were investigated by indoor soil column experiments. The results showed that the presence of concrete fragments promoted the wetting peak transport distance and cumulative infiltration, and the promotion effect increased gradually with the increase of the ratio, but there was a threshold value, and the promotion effect was least when the ratio was 20%. When the evaporation period was 35 d, concrete fragment treatment can increase the cumulative evaporation and promote the evaporation of urban soil moisture; the promotion effect increases with the increase of the proportion, but there is a threshold value; when the proportion is 20%, the promotion effect is the smallest. The evaporation rate was consistent with the different stages of evaporation process during evaporation. The concrete fragment treatment reduced the time required for moisture to reach the same depth during infiltration; the moisture coefficient of variation of the concrete fragment treatment during evaporation showed a trend of decreasing, then increasing, and then decreasing, which increased the uncertainty of moisture in the evaporation process. The model simulation results show that the models such as the power function, Kostiakov model, and Rose model fit well, and the coefficient of determination R 2 is greater than 0.99, among which the Kostiakov model fits best. The research results can provide a theoretical scientific basis for building an efficient ecological city.