Soil Mechanics (141-160)

Updated: Apr 27, 2020

141. The net ultimate bearing capacity of a purely cohesive soil

is independent of both depth and width of footing

142. The rise of water table below the foundation influences the bearing capacity of soil mainly by reducing cohesion and effective unit weight of soil


143. Terzaghi's general bearing capacity formula for a strip footing


ultimate bearing capacity

where C = unit cohesion

γ = unit weight of soil

D = depth of foundation

B = width of foundation

Ne, Nq, Nγ = bearing capacity factors

144. Terzaghi's bearing capacity factors Nc, Nq and Nγ are functions of

angle of internal friction only

145. In the plate loading test for determining the bearing capacity of soil, the size of square bearing plate should be between 300 mm and 750 mm


146.

a) Bearing capacity of a soil depends on the type of soil.

c) Bearing capacity of a soil depends upon shape and size of footing.

d) Bearing capacity of a soil is indepen dent of rate of loading

147. A 600 mm square bearing plate settles by 15 mm in plate load test on a cohesionless soil under an intensity of loading of 0.2 N/mm². The settlement of a prototype shallow footing 1 m square under the same intensity of loading is

between 15 mm and 25 mm

148. A 300 mm square bearing plate settles by 15 mm in a plate load test on a cohesive soil when the intensity of loading is 0.2 N/mm². The settlement of a prototype shallow footing 1 m square under the same intensity of loading is

50 mm

149. Rise of water table in cohesionless soils upto ground surface reduces the net ultimate bearing capacity approximately by 50%

150. Contact pressure beneath a rigid footing resting on cohesive soil is

more at edges compared to middle

151. According to IS specifications, the minimum depths of foundation in sand

and clay should be respectively 800 mm and 900 mm


152.The maximum differential settlement in isolated footings on clayey soils should be limited to 40 mm


153. A combined footing is generally used when number of columns is two and they are spaced close to each other


154. Negative skin friction on a pile acts downward and reduces the load

carrying capacity of the pile

155. A single acting steam hammer weighing 22.5 kN and falling through a height of 1.2 m drives a pile. If the final set is 12.5 mm, then according to Engineering News formula

allowable load for the pile is 300 kN


156. Generally the bearing capacity of a pile group is equal to the sum of bearing capacities of individual piles in case of end bearing piles

157. The settlement of a group of friction piles as compared to that of a single pile is more

158.Negative skin friction is caused by relative settlement of soil and skin

frictional resistance is caused by re lative settlement of pile.

159.a) Static formulae are suitable for friction piles driven through cohesive

soils.

c) Dynamic formulae are suitable for friction piles driven through cohesionless soils.

d) Dynamic formulae do not take into account the reduced bearing capacity

of a pile in a group

160. Mechanical stabilization of soil is done with the help of

proper grading


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