Principles of Geotechnical Engineering (MindTap Course List)
9th Edition
ISBN: 9781305970939
Author: Braja M. Das, Khaled Sobhan
Publisher: Cengage Learning
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Chapter 16, Problem 16.14P
Redo Problem 16.13 with the following data: gross allowable load = 184,000 lb, γ = 121 lb/ft3, c′ = 0,
16.13 A square footing (B × B) must carry a gross allowable load of 1160 kN. The base of the footing is to be located at a depth of 2 m below the ground surface. If the required factor of safety is 4.5, determine the size of the footing. Use Terzaghi’s bearing capacity factors and assume general shear failure of soil. Given: γ = 17 kN/m3, c′ = 48 kN/m2,
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A square footing of 4 m side is placed at
1 m depth in a sand deposit. The dry unit
weight (y) of sand is 15 kN/m³. This
footing has an ultimate bearing capacity
of 600 kPa. Consider the depth factors:
d = d, = 1.0 and the bearing capacity
%3D
%3D
factor : N, = 18.75. This footing is
%3D
placed at a depth of 2, in the same soil
deposit. For a factor of safety of 3.0 as
per Terzaghi's theory, the safe bearing
capacity (in kPa) of this footing would
be
6. [Soil Bearing Capacity] (
Assume the general shear failure and use a factor of safety 2.8. Determine the follow
N. = 25.13 , N, = 12.72, N,y = 8.34
a. The gross allowable bearing capacity.
b. Net Allowable bearing capacity
c. The safe load that the footing can carry.
). A circular footing 3 m in diameter is shown below.
%3D
Ground surface
Y = 18.5 kN/m²
C = 80 kPa
0 = 25°
1.1 m
Dr = 1.8 m
Water table
Tse = 19.2 kN/m?
Diameter =
3 m
The foundation design for the constmction of a telecommunication mast is to support a
concentric load of 800kN and to be inclined at 80° to the horizontal, a I .5mxl .5m footing is
to be placed at 2.0m below ground level as shown in Figure 2. The soil properties are;
C=70kN/m², Y=18KN/m³ , 4–30° Assume the ground water table to be deep
a). Determine the expected foundation pressure at the base of the footing due to the application
of the load.
b). Using the Meyerhof's bearing capacity equation, determine the ultimate bearing capacity of
the underlying soil.
c). Determine the factor of safety of the design, and comment on the adequacy of the design in
terms of shear failure, give recommendations should the design is not safe against shear failure
Q=800kN
80
2.0m
1.5m
Figure 2
Chapter 16 Solutions
Principles of Geotechnical Engineering (MindTap Course List)
Ch. 16 - A continuous footing is shown in Figure 16.17....Ch. 16 - Refer to Problem 16.1. If a square footing with...Ch. 16 - Redo Problem 16.1 with the following: = 115...Ch. 16 - Redo Problem 16.1 with the following: = 16.5...Ch. 16 - Redo Problem 16.1 using the modified general...Ch. 16 - Redo Problem 16.2 using the modified general...Ch. 16 - Redo Problem 16.3 using the modified general...Ch. 16 - Redo Problem 16.4 using the modified general...Ch. 16 - Prob. 16.9PCh. 16 - If the water table in Problem 16.9 drops down to...
Ch. 16 - Prob. 16.11PCh. 16 - A square footing is subjected to an inclined load...Ch. 16 - A square footing (B B) must carry a gross...Ch. 16 - Redo Problem 16.13 with the following data: gross...Ch. 16 - Refer to Problem 16.13. Design the size of the...Ch. 16 - Prob. 16.16PCh. 16 - Prob. 16.17PCh. 16 - Refer to the footing in Problem 16.16. Determine...Ch. 16 - Figure 16.21 shows a continuous foundation with a...Ch. 16 - The following table shows the boring log at a site...
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- A 2 m 3 m spread footing placed at a depth of 2 m carries a vertical load of 3000 kN and a moment of 300 kN m, as shown in Figure P6.14. Determine the factor of safety using Meyerhofs effective area method. Figure P6.14arrow_forwardA footing 2.5 × 2.5 m carries a pressure of 400 kPa at a depth of 1m in sand. The saturated unit weight of the sand is 20 kN/m3 and the unit weight of the sand above the water table is 17 kN/m3 . The design shear strength parameters are ?′ = 0 kPa and ?′ = 40o .Determine the bearing capacity of the footing for the following cases using EC7 - Design Approach 1:a. The water table is 5 m below ground levelb. The water table is 1 m below ground levelc. The water table is at ground level with vertical seepage upwards under ahydraulic gradient of 0.2.arrow_forwardA square footing of 4 m side is placed at 1 m depth in a sand deposit. The dry unit weight (y) of sand is 15 kN/m³. This footing has an ultimate bearing capacity of 600 kPa. Consider the depth factors : d = d = 1.0 and the bearing capacity factor N₁ =18.75. This footing is Y placed at a depth of 2, in the same soil deposit. For a factor of safety of 3.0 as per Terzaghi's theory, the safe bearing capacity (in kPa) of this footing would bearrow_forward
- a) A square footing placed at a depth of 1 m is required to carry a load of 1000 kN. Find the required size of footing given the following data. C = 10 kPa, ϕ = 38o, γ = 19 kN/m3, Nc = 61.35, Nq = 48.93, Nγ= 74.03 and F = 3.Assume water table is at the base of footing.arrow_forward). A circular footing 3 m in diameter is shown below. 6. [Soil Bearing Capacity] (* Assume the general shear failure and use a factor of safety 2.8. Determine the follow N. = 25. 13 , Nq = 12.72, N, = 8.34 a. The gross allowable bearing capacity. b. Net Allowable bearing capacity c. The safe load that the footing can carry. Ground surface Y= 18.5 kN/m? C = 80 kPa = 25° 1.1 m D,- 1.8 m Water table Ye = 19.2 kN/m? Diameter = 3marrow_forwardA square footing shown has the following details: Unit weight of soil = 17.66 kN/m3 Saturated unit weight of soil = 21.32 kN/m³ cohesion = 28.20 kPa %3D friction angle = 30 degrees %3D B = 1.61 meter Df = 1.60 meter P 1,559.97 kN e/B = 0.14 --> one way eccentricity Calculate for the gross factor of safety. Use Meyerhof General Bearing Capacity Formula. D. BXB Water tablearrow_forward
- What is the net ultimate bearing capacity of a footing 2.5 mx 2.5 m built on a sand of unit weight 16 kN/m³ and having an angle of friction of 25°. The depth of the footing is 1.5 m below the ground surface. No = 5.6 and N₁ = 3.2.arrow_forwardA continuous footing has the following properties. Using Terzaghi’s bearing capacityfactors, determine the gross allowable load per unit area (qall) that the footing can carry.Assume general shear failure. 3544.12 psfGiven: ∂sat = 115 pcf Df = 2ftc =400 psf B = 2.5 ftφ= 250 FS= 4.0 Solve if water table is located (a) 2 ft , (b) 3 ft below ground surface. ANSWERS 3407.55, 3472.6arrow_forwardA 1.2 m. wide wall footing was constructed on the surface of a silty sand soil. If the bottom of the footing is embedded to a depth of 0.75 m. from the ground surface, determine the percent increse of the bearing capacity. Unit weight of silty sand soil = 18.88 kN/m³ angle of friction 0 = 30° and is cohesionless. Bearing capacity factors: Nc = 37.16 Ng = 22.46 Ny = 19.13 wall footing or strip footing 1.2 m Ans. 146.76%arrow_forward
- A footing 2.50 m x 2.50 m is located at a depth of 1.5 m in sand. The shear strength parameters to be used in design are c' = 0 and o' = 38°. What is the net ultimate bearing capacity of footing if the water table is at 3 m below foundation level? The unit weight of sand is 18 kN/m3 and FOS = 3 For O' = 38°, N, = 67 and Ng = 49arrow_forward67. A strip footing is to be designed to carry a gross load of 900 kN/m at a depth of 1 m in a gravelly sand. The appropriate shear strength parameters C = 0 and 6 = 38°. Determine the width of the footing if a factor of safety of 3 against shear failure is to be assured. Water table is found to be at foundation level. Above the water table, the saturated unit weight is 18 kN/m³ and below the water table, the saturated unit weight is 20 kN/ m³. For = 38°, the bearing capacity factors are: N = 49 and N = 67. Unit weight of water q is 9.8 kN/m³.arrow_forwardA strip footing (8 m wide) is designed for a total settlement of 40 mm. The safe bearing capacity (shear) was 150KN/m? and safe allowable soil pressure was 100 kN/m?. Due to importance of the structure, now the footing is to be redesigned for total settlement of 25 mm. The new width of the footing will bearrow_forward
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