Abstract: In order to explore the correlation between soil-water characteristics and microstructure of soil-rock mixtures in Qinling Bashan Mountains, unsaturated infiltration test and mercury intrusion test were carried out on soil-rock mixtures with different void ratios and rock contents. The test results show that the soil-water characteristic curve of soil-rock mixture under high compaction and low rock content is obviously higher than that under low compaction and high rock content. The pore size which affects the soil-water characteristics of soil-rock mixtures is within the range of less than 200μm. For the soil-rock mixture sample with low rock content, increasing the compaction degree will cause the pores to concentrate in the range of small pore size, thereby making the soil-water characteristic curve steeper in this pore size range. For the sample with high rock content, increasing the compaction degree mainly compresses the large pore (d>80μm), which has almost no effect on small pores, resulting in the consistency of soil water characteristic curve within the research scope. When the compactness is high, increasing the rock content causes the pore size distribution of the soil-rock mixture to be more uniform, and the soil-water characteristic curve changes from steep to gentle. For the soil-rock mixture with low compactness, the structure of small pores under different rock content conditions has little difference, which makes the soil water characteristic curve from different samples relatively consistent.

Key words: soil-rock mixture, rock content, void ratio, soil-water characteristic curve, microstructure