Experimental study on water infiltration of soil containing rock fragments

Field soils contain some rock fragments,particularly,forest soil that usually has considerable amount of rock fragments.However,there is little information on the effects of the amount and the size of rock fragment on the infiltration in research paper.Based on the experiment of one-dimensional vertical infiltration in laboratory conditions,the effect of different soil-stone ratios and constitutes of rock fragments on the infiltration rate and the wetting front of the mixtures are studied.The results show that the infiltration rate and the wetting front increase with the increase of coarse-fragments for a given time.The relationship between the infiltration rate and the time can be described by the Kostiakov infiltration model;the relationship between the wetting front and time can be fitted well by one short power progressional solution of the Philip infiltration equation; and the parameters of the Kostiakov infiltration model and one short power progressional solute of the Philip infiltration equation are all fitted the power equation with the increase of soil-stone.The effect of the size and constitutions of rock fragments on the infiltration rate is expressed in the content of rock fragment after correlate analyses.In addition,rock fragments with 2-3 mm in diameter give negative correlation with the infiltration process,while rock fragments greater than 25mm in diameter are favorable to water flow in the mixture.The results of the present study may provide important data and be useful for the profound understanding of water cycle in stony soils.