The Effect of Cracks Propagation on Cohesion and Internal Friction Angle for High Plasticity Clay

Abstract

Slope events usually precede the occurrence of small cracks in soil on the slopes. The small cracks become deep crack and will be a potential landslide. If the potential landslide plane is getting longer, the slope will occur sliding. The small cracks in the soil are usually not visible so the soil is still considered to be intact, not cracked. At the time of soil sampling in the field and testing in the laboratory, the soil is regarded as intact soil and not cracked. This research aims to determine the effect of crack propagation in the soil against changes in cohesion values and internal shear angle in laboratory testing. A series of laboratory tests using a modified shear test apparatus was performed. Direct shear testing using a modified shear test apparatus was carried out on a high plasticity clay soil. The crack propagation given is 25%, 50%, 75% against the diameter of the specimen. The results showed that crack propagation occurring in the soil is very influential on cohesion. In a crack condition of 100% then the value of soil cohesion becomes zero. Other results showed that crack propagation did not affect the internal shear friction angle. Regardless of the length of the crack that occurs, the internal friction angle remains as in the conditions have not been cracked.