| Summary: | 碩士 === 國立臺北科技大學 === 土木與防災研究所 === 100 === The increase of landslide events in recent years was mostly caused by heavy rainfall as a result of extreme climate change. On 28th September, 2008, a heavy rainfall led to the failure of the slope next to tower T16 of Maokong Gondola in the Wenshan District area of Taipei city. Water from the ground surface infiltrated into the initially unsaturated slope and caused its moisture content to increase and, subsequently, its matric suction to decrease. As a result, the shear strength of the slope dropped and thus triggered the landslide. It is thus important to consider the water infiltration effect during the design of slopes.
This study investigates the effect of water infiltration on the shear strength of unsaturated low plasticity ML/CL soil obtained from Maokong landslide. A series of laboratory tests including the physical test, soil water characteristic test and triaxial shearing test were conducted in order to understand the characteristics of the soil in an unsaturated condition. The shear strength obtained from the constant suction triaxial shearing test was then quantitatively compared with the shear strength obtained from the triaxial shearing-infiltration test. Their corresponding extended Mohr-Coulomb failure envelopes were then proposed.
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