Abstract: Settlement and deformation of the earth-rock dam body after completion is an important concern in engineering practice. In this work, an experiment was conducted on the compression characteristics of a gravel-mixed soil material－an aeolian sandy soil material mixed with a granite gravel material, focusing on the influence of gravel proportion, stress level, and compactness. The test results show that the compressibility of this mixture is significantly higher than that of the soil; its compression modulus increases with the increasing vertical stress, but with a further vertical stress increase, the increase rate of the modulus decreases gradually. Both gravel proportion and compactness have an evident effect on the modulus. With an increase in gravel proportion or compactness, compression modulus shows a basically increasing trend. However, we also find excessive gravel proportion will reduce compression modulus due to particle breakage caused by the vertical stress of gravel. The void ratio of gravel-mixed soil decreases with vertical stress; it decreases rapidly under low stress while it tends to be stable under high stress. Finally, combining with the variation trends in compression modulus, we investigate the optimal adjustment of gravel proportion in the core wall at different heights of the dam body.

Key words: gravel-mixed soil, compression characteristics, gravel proportion, stress level, compactness