PE-13-Slope-Stability

PE-13-Slope-Stability - 13 - Slope Stability *01: Find the...

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13 - Slope Stability *01: Find the FS of a straight wedged element of slope. *02: Swedish slip circle used to find the FS of a slope. *03: Method of slices to find the FS of a slope. *04: Method of slices to find the FS of a slope. *05: Field evaluation of the stability of a loaded river bank. 280
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*Slope-01: Factor of Safety of a straight line slope failure. (Revision: Oct.-08) A slope cut to 1.5H:1V will be made in a shale rock stratum that has bedding planes that have an apparent dip of 16˚ (see the figure below). If the acceptable factor of safety against failure is at least 2 along the lower-most bedding plane, is this slope stable? Use a unit weight of 20.1 kN/m 3 , and bedding strength parameters of c = 22 kPa and φ = 30˚. 85.0 m Original ground surface 1.5 11.3 m L 20.0 m 1 Rock’s bedding planes 16º Proposed new ground surface Solution: () 3 The traingule of rock above the potential slip plane has a weight per unit width, 1 85.0 11.3 20.1 9,650 2 The length of the slip plane is, 88.4 cos16 Therefore, Resisting For W kN Wm m mm L m Lm FS ⎛⎞ == ⎜⎟ ⎝⎠ ° = 2 cos tan ces Driving Forces sin 22 tan 30 6 2 1 2.7 cL W W O m m K αφ α +⎡ ⎣⎦ ⎡⎤ ° ⎢⎥ ° > 281
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*Slope-02: Same as Slope-01 but with a raising WT. (Revision: Oct.-08) In the previous problem the slope appeared to be stable with a factor of safety = 2.7. What happens to that factor of safety if the water table rises to the level shown below? Use a unit weight of 20.1 kN/m 3 , and bedding strength parameters are reduced by the effective parameters of c ’ = 15 kPa and φ = 20˚. 85.0 m Original ground surface 3.2 m 1.5 11.3 m 20.0 m Seepage 1 Rock’s bedding planes 16º Proposed new ground surface Solution: The weight of the rock triangle per unit width is still 9,650 T he length of the slip plane is still 88.4 .
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This note was uploaded on 09/11/2011 for the course CEG 4011 taught by Professor Staff during the Summer '10 term at FIU.

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PE-13-Slope-Stability - 13 - Slope Stability *01: Find the...

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