Abstract:
In most cases of landslide in Indonesia and elsewhere in the world there is the fact that landslide occurred during
heavy rains, landslide may occur anytime in the rainy season, landslide occurs on rocky slopes or on the stiff silty
or clayey soilwith a hard layer, landslide occurs on relatively gentle slopes, landslide does not occur on all part of
the slopes even though the condition of rocks and soil along the side of the road is relatively same and the intensity
of rainfall are practically the same. In areas with frequent landslide, the data surveyed from some field drill results
on the ground outside the landslide area showed that the layers of soil on the slopes of the mountains was not
saturated, and the ground water level is quite deep. A preliminary investigation showed that the soil cracks has
occurred on the slope. The cracks occur due to soil movement or weathering by plant. Cracks in the soil can be
short or long and even form a potential areas of landslides on the slopes. The cracks area is then filled by rainwater.
This rainwater that fills the cracksarea causes the independent pore water pressure on the slopes. The purpose of
this research is to analyze the influence of cracks on the shear strength parameters of cohesion (c ') and the internal
friction angle (). A series of laboratory activities carried out by varying the cracks in the test specimen ranging
from 0% to 75% then testing using the direct shear test tool that has been modified. The results showed that the
cracks in the soil greatly affects the decrease in cohesion but did not significantly affect to the internal friction
angle.
