Abstract: A series of splitting tests was carried out on the intact and remolded loess specimens by particle image velocimetry (PIV) test system, and the microstructure of the intact and remolded loess specimens were quantitatively analyzed by mercury intrusion porosimetry (MIP), so as to discuss the influence of the structure and initial dry density on the tensile strength. The test results show that the peak load of the intact specimens is bigger than that of the remolded specimens when the specimens splitting failure. The peak load of the remolded specimens increases with increasing initial dry density. The displacement vector field shows that the primary cracks incline and the secondary cracks do not develop during the split failure of the loess specimens. When the remolded specimens split, the primary cracks are radially vertical, the secondary cracks more develop, and the crack morphology of the remolded specimens with different initial dry densities is basically the same. For the equal initial dry density, the cumulative intruded porosimetry volume curve and pore diameter distribution density curve of the intact specimen are both higher than those of the remolded specimen, and the inter-aggregate pores of the intact specimen are more than those of the remolded specimen. However, due to the obvious structure, the tensile strength of the intact specimen is higher than that of the remolded specimen. As the initial dry density increases, the cumulative intruded porosimetry volume curve of the remolded specimen moves downward, and the peak of the pore distribution density curve moves to the left. The inter-aggregate pores gradually decrease or even disappear. As a result, the tensile strength increases with increasing initial dry density.

Key words: intact loess, tensile strength, displacement vector field, crack, mercury intrusion