Landslide Essay

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1.1 Introduction to Landslide
A landslide is a geological phenomenon, which includes a wide range of ground movements, such as deep or shallow failure slopes and rock falls. See figure 1.1. 1.1.1 Factors influence Landslides Landslides occur when the stability of the slope turns from the stable state to unstable state. Most of the Landslides usually cause depend on two main factors: (i) Natural Factors and (ii) Anthropogenic Factors. (USSG, 2004)
(i) Natural Factors
(a) Geological factors: If the geological conditions of a slope are weak or sensitive materials, jointed, weathered materials, sheared, fissured materials, adversely oriented discontinuity (schistosity, fault, bedding, contact, unconformity, and so forth) and the contrast in permeability or stiffness of
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Water can cause the strength of the material to become lower, it cannot resist the force of gravity. Water also can reduce the frictional force and it can make easier to move material downhill. See figure 1.3.
1.2 Types of Landslides Generally, there are five major types of landslides (Lynn M. et. al., 2008) (See figure 1.4). They are as follows:
(i) Falls (Rockfalls)
They are abrupt movements of materials. They become detached from steep slopes or cliffs moving by free-falling, bouncing, and rolling.
(ii) Flows
They include many types of mass movement, like a creep, debris flow, debris avalanche, lahar, mudflow, and earthflow.
(a) Creep: They are a slow steady downslope movement of soil or rock. They can easily notice by seeing the curved tree trunks, walls, fences, and lamp- posts.
(b) Debris Flow: In the conditions of loose soils, if rocks and organic matter combined with air and water, they become liquefied and slurry then rapid mass flow occurred. They flow down along the slope in the steep gullies with a moderate of high

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