LARGE SCALE TRIAXIAL TESTING ON MECHANICAL PROPERTIES OF BROKEN LIMESTONE UNDER VARIOUS STRESS PATHS

In order to acquire mechanical properties of the broken limestone of Kunming new airport as well as that affected by water, large scale triaxial tests were conducted. Both triaxial tests under various stress paths and contrast tests of constant σ′₃ compression under dry and wet conditions were carried out. The test results show that peak stress and initial modulus, under the condition of Δσ′₁≥0, increase as confining pressure or stress ratio k (the ratio of minor principal stress increment to maximum principal stress increment) increases, while the dilatancy is restrained gradually. Furthermore, dilatancy and shrinkage behaviors of broken limestone are strongly related with the stress paths. The shear strength of broken limestone is of high nonlinearity. The shear strength under the stress path of reducing confining pressure is slightly lower than that under constant σ′₃. Finally, water has considerable influence on the shear strength, initial modulus and dilatancy of broken limestone. This research provides experimental basis for establishing constitutive models of coarse-grained fills, considering the influence of various stress paths.