Rock-soil aggregate mixture come from excavation is broadly used as filling in roadbed and foundation for its high density and convenience construction; affected by geology

rock-soil ratio

grain size distribution and other factors

the mechanical behavior of rock-soil aggregate mixture puts up obviously nonlinearity; additionally its intensity index can’t detect by routine tests

so that roadbeds or foundations filled with rock-soil aggregate mixture always occur a rather large differential settlement or slump

severely affecting the function of superstructure. To disclose its intensity character and variety rules with influencing factors

this study improved large scale direct-shear test

developed a large scale direct-shear test system

using this improved large scale direct-shear test system

carried out shear test on different kinds of rock-soil aggregate mixtures. The results show that the shear destroying rule of the mixture did not obey Coulomb law on high stress condition; its intensity should be discounted. Test results show the variety tendency of intensity index with influencing factors; the elementary rules of the friction angle varied with apiece influence factor are established. Test results also show that the character of native rock and rock-soil ratio of mixture have relatively bigger influence to the intensity index; the friction angle of hard rock mixture general is greater than that of soft rock mixture; rock-soil ratio has little influence on the intensity while the rock-soil ratio less than 30 %; the intensity of mixture increases with the increment of rock-soil ratio as parabolic curve

generally reach peak value at the ratio about 70 %.