Stone column is composed of broken stones

among which the interconnections are very small. Thus the mechanical characteristics of broken stones depends on their densites and lateral pressure mainly. The deformation characteristics of broken stones are studied by the large scale triaxial shear tests and axial compression tests

the laws about broken stones are drawn according to the test results as follows: the relationship between the deviator stress and axial strain is close to a hyperbola and the relationship between the volume strain and the axial strain is similar to a parabola for the triaxial shear tests; the relationship between the axial stress and the axial strain are near to a power function curve for the axial compression tests. The test for the composite foundation of stone columns of Xu-Su Expressway is described in detail. The results show that the liquefaction potential has been eradicated when the stone columns are used to treat the soil foundation of this area. The tests and results have a referential value to the similar engineering problems.