The brittleness index exhibits the strain-softening behaviour of soil and is often used to access the shear mechanism in slope failure. It has been widely investigated for diffirent materials, especially for brittle materials. | Brittleness index of lightly cemented soil in ring shear tests gt NGUYEN THANH DUONG1 NGUYEN VAN HAI2 1 Hanoi University of Mining and Geology Email nguyenthanhduong@ 2 Mien Trung University of Civil Engineering Email nguyenvanhai@ ABSTRACT contractive behavior IB 0 indicates the peak strength f residual strength r no strength loss there is no strain-softening The brittleness index exhibits the strain-softening behaviour of and the soil shows a highly dilative behavior. The rate of strength soil and is often used to access the shear mechanism in slope loss can be an indicator of progressive failure or flow slide. Bishop et al. 1971 showed that there were three factors afftecting the failure. It has been widely investigated for diffirent materials brittleness of a soil including Dilatancy at failure reorientation especially for brittle materials. However the brittleness index of and cementation bond. Taylor 1948 Skempton and Bishop 1950 lightly cemented soils has not been investigated yet. In this study indicated that the difference between peak and residual strength of sand was directly related to the rate of dilatancy at failure. the brittleness index of lightly cemented clay simulated by adding Accordingly the IB values increased as the rate of dilatancy a small content of cement to clay will be investigated in ring shear increased and decreased as the effective normal stress increased Bishop et al. 1971 . For remoulded samples since the test. A series of ring shear tests were conducted at different cementation bond was destroyed and there was no dilatancy effective normal stress levels from 98 kPa to 392 kPa and shear behavior the brittleness of remoulded clay was closely related to rates from mm min to 20 mm min. The test results showed the reorientation of the platy clay particles. For undisturbed samples with natural cementation bond weathered and that the brittleness index decreases with the increasing of unweathered blue London .
