ESE 2021 Technical Quiz ||Designs and Construction of Gravity dams
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A masonry dam 10 m high is trapezoidal in section with a top width of 1 m and bottom width of 8 m. The dam experiences the net vertical force of 1100000 kN and horizontal force of 500000 kN. If the coefficient of friction is 0.75 and permissible shear stress of joint is 14 kg/cm2 then the shear friction factor is
The top width and the bottom width at river thalweg level of a concrete gravity dam are 6 m and 24 m respectively. The vertical section of the dam at the thalweg alignment is 38 m above the thalweg. The upstream face is vertical and the depth of water on the upstream side is 36 m. the moment of hydrostatic force about the toe at that level is
The forces which are taken into account for the analysis of elementary profile of dam under the empty reservoir condition are:
(i) Water pressure
(ii) Uplift forces
(iii) Self weight of the dam
(iv) earthquake forces
Statement 1: The shear strength of joint must also be considered along with frictional forces in resisting the horizontal forces in large dams.
Statement 2:The factor of safety against sliding is the ratio resisting frictional stresses to the horizontal forces.
At the base of a gravity dam section, the vertical stress at the toe was found to be 2.4 MPa. If the downstream face of the dam has a slope of 0.707 horizontal :1 vertical, and if there is no tail water, the maximum principal stress at the toe of the dam is