Concept explainers
State whether the following are true or false.
- a. Load carrying capacities of timber piles are less than those of steel or concrete piles.
- b. If the load carried by the pile cross section decreases linearly with depth, the frictional resistance per unit remains the same at all depths.
- c. The point load is mobilized well before the shaft load.
- d. Soil-pile friction angle δ′ can be greater than the friction angle of the soil ϕ′.
- e. Bored piles are high displacement piles.
(a)
State whether the statement “Load carrying capacities of timber piles are less than those of steel or concrete piles” is true or false.
Answer to Problem 18.1P
The given statement is
Explanation of Solution
The steel piles have a usual load carrying capacity of 300kN to 1200kN.
The concrete piles have a load carrying capacity of 300 kN to 3000 kN.
The timber pile has a load carrying capacity value of 300 kN to 500 kN.
Hence, the load carrying capacities of timber is less than concrete or steel.
Therefore, the given statement is
(b)
State whether the load carried by the pile cross section decreases linearly with depth and the frictional resistance per unit remains the same at all depths is true or false.
Answer to Problem 18.1P
The given statement is
Explanation of Solution
Determine the unit area frictional resistance
Here, p is the pile cross section perimeter,
As per the formula, the change in pile load remains constant, when the pile load is increasing linearly with depth. Conversely, the perimeter and the change in depth have the inverse relationship with depth. Therefore,
Therefore, the given statement is
(c)
State whether the point load is mobilized well before the shaft load is true or false.
Answer to Problem 18.1P
The given statement is
Explanation of Solution
If the shaft load is large, it depends on the pile diameter. The ultimate shaft resistance is not principally mobilized before the point load
Therefore, the given statement is
(d)
State whether the statement “soil-pile friction angle
Answer to Problem 18.1P
The given statement is
Explanation of Solution
The magnitude of soil-pile friction angle
Therefore, the given statement is
(e)
State whether the given statement “bored piles are high displacement piles” is true or false.
Answer to Problem 18.1P
The given statement is
Explanation of Solution
Bored piles cause the soil to be displaced radially as well as vertically as pile shaft is driven. For bored piles, the holes are initially bored in the ground and then pile is formed in this hole. Bored piles displace very less amount of soil.
Therefore, the given statement is
Want to see more full solutions like this?
Chapter 18 Solutions
Fundamentals of Geotechnical Engineering (MindTap Course List)
- A 20 m long concrete pile is shown in Figure P12.2. Estimate the ultimate point load Qp by a. Meyerhofs method b. Vesics method c. Coyle and Castellos method Use m = 600 in Eq. (12.28).arrow_forwardA steel pile (H-section; HP 360 1.491; see Table 18.1) is driven into a layer of sandstone The length of the pile is 18.9 m. Following are the properties of the sandstone: Unconfined compression strength = qu(lab) = 78.7 MN/m2 Angle of friction = 36 Using a factor of safety of 3, estimate the allowable point load that can be carried by the pile. Use Eq. (18.42).arrow_forwardA 10m long and 0.8m diameter precast concrete pile is driven into a saturated clay deposit as shown in the figure below. The groundwater table is at the ground surface. For the ratio of the undrained shear strength to vertical effective pressure is approximated as follows: = 0.11 + 0.0037(PI) NC (9- 9 (OCR)8 OC Determine the bearing capacity for the pile by the a) Alpha (a) method. b) Lambda (A) method Depth, m Layer 1 OCR = 5, Yat = 19.5 kN/m³, Pl = 35 Layer 2 OCR = 1.5, %at = 19.0 kN/m, Pl = 25 Layer 3 OCR = 8, %at = 19.5 kN/m, Pl = 20 10 D, = 0.8 m D 10 marrow_forward
- FDE 016: A prestressed concrete pile, 400 mm x 400 mm in cross-section, is to be driven in a clayey soil as shown. Use alpha method with factor of safety of 2. Soft Clay 17-15.7 kN/m² c=32 kPa 8 m Stiff Clay * = 19 kN/m² Cu = 90 kPa = 0.5 Refer to FDE 016. What is the end bearing capacity of pile in KN? Select the correct response: 251.84 184.25 129.60 245.32 6 m.arrow_forwardQ.7 (a) A 500 mm diameter bored concrete pile is to be formed in the soil profile as shown in figure. The ground conditions are as follows: Granular soil: Dense gravel: Glacial clay: Depth (m) Adhesion factor, cat 7.0 m = 120 kPa c at 8.0 m 145 kPa cat 11.0 m 220 kPa 0 3 7 8 Y = 20 kN/m³ $' = 22.5° K₁ = 1.0 Y= 21 kN/m³ ' = 26.25° 11 K, = 2.0 Y = 20 kN/m³ α = 0.6 N = 9.0 Granular soil Dense gravel Glacial clay Determine the ultimate bearing capacity of the pile for: (a) Embedded length of 8 m (b) Embedded length of 11 marrow_forwardQUESTION 3 A concrete pile is driven into top two layers of subsoil strata made of 10m and 5m thick saturated clays respectively. The pile's diameter is 500 mm throughout the pile. Determine the allowable bearing capacity of the pile. The subsoil properties are shown. (Answer 454 kN). Clay layer 1: Saturated unit weight of clay = 18kN/m3 Average undrained shear strength = 100kPa, o = 0 %3D Adhesion factor = 0.48 Clay layer 2: Saturated unit weight of clay = 19kN/m3 Average undrained shear strength = 120kPa, q = 0 Adhesion factor = 0.42, Nc = 9.arrow_forward
- Q1: Determine the allowable load capacity for the driven pile of 0.6 m diameter embedded in a layered soil as shown in the figure below, use F.S 2.0 , K, = 1.5 and tand =0.5? ELEV. 110 N.C.C W.T ELEV. 108 Cu =70 kPa Y = 17 kN/m3 a = 1, yw = 10 kN/m? ELEV. 102 O.C.C, Cu 180 kPa, y = 20 kN/m³ a = 0.45 ELEV. 98 Sandy Layer Yt = 19 kN/m3 Ø = 32° Nq = 23.18 ELEV. 90arrow_forwardIn Hiley’s formula for driven piles i.e. R=E/(s+0.5c), why is a coefficient of 0.5 applied for the term elastic deformation of piles and soil?arrow_forwardA concrete pile having a diameter od 0.30m. Is driven into a loose sand having a unit weight of 20 kN/cu.m Coefficient of friction between sand and pile is 0.40. Bearing capacity factor Nq=80. Lateral pressure factor K =0.90 Allowable load of pule is 170 kN. Fs= 3.25 Determine the following A. Ultimate bearing capacity of file B. Ultimate frictional capacity of pile C. Length of the pilearrow_forward
- 1) A 0.5 meter diameter (D) concrete pile is driven into a sand deposit with y moist = 18.7 kN/cubic meter and o= 31 degrees. The water table is very deep. a. Assume Nq = 68.2. b. Assume K= 0.727 (Effective Earth Pressure Coefficient) c. Assume ô (friction of concrete surface to sand) = 24.8 (0.8 Tan 4) ESTIMATE PILE SHAFT ULTIMATE CAPACITY ASSUMING PILE IS 40 METERS LONG USING MEYERHOF'S METHOD. Assume critical depth is 15D. Hint: pile perimeter is 1.571 Marrow_forwardProblem #1 A 20-m-long concrete pile is shown Below. Estimate the ultimate point capacity Op by: a. Meyerhof's method b. Vesic's method c. Coyle and Castello's method Use m= 600 in Eq. (9.26). Estimate the side resistance Qs by: a. Using Eqs. (9.40) through (9.42). Use K = 1.5 and 8 = 0.60 b. Coyle and Castello's method [Eq. (9.44)] l-20 m Concrete pile 460 mm X 460 mm Loose sand $₁ = 30° y = 18.6 kN/m³ 18.6x2 = 372 kr/m² Dense sand $2 = 36 y = 18.5 kN/m²arrow_forward3. A dnven closed-ended pile, circular in cross section, is shown. Calculate the following. a. The ultimate point load using Meyerhof's procedure. b. The ultimate point load using Vesıc's procedure. Take ,= 50. c. An approximate ultımate point load on the basıs of parts (a) and (b). d. The ultımate frictional resistance Qs, K= 1.4; 8'=0.8Ø' e. The allowable load of the pile (use FS= 4). y = 15.7 kN/m = 32° c' = 0 3 m Groundwater table - 18.2 kN/m Ysat 6' = 32° c' = 0 3 m Yat - 19.2 kN/m³ ' = 40" c' = 0 15 m 381 mmarrow_forward
- Fundamentals of Geotechnical Engineering (MindTap...Civil EngineeringISBN:9781305635180Author:Braja M. Das, Nagaratnam SivakuganPublisher:Cengage LearningPrinciples of Foundation Engineering (MindTap Cou...Civil EngineeringISBN:9781337705028Author:Braja M. Das, Nagaratnam SivakuganPublisher:Cengage Learning