Principles Of Foundation Engineering 9e
9th Edition
ISBN: 9781337705035
Author: Das, Braja M.
Publisher: Cengage,
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Chapter 14, Problem 14.2P
In a piled raft, 450 mm diameter and 13 m long piles are placed in a rectangular grid at 1.60 m × 1.63 m spacing. Find the pile-raft interaction factor
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2.
Consider a group of 450 mm x 450 mm reinforced concrete piles were driven into
thick loose sand layer with the average unit weight and internal friction angle of 16 kN/m3
and 30°, respectively. Estimate the group pile capacity with the arrangement as shown in
Figure Q2 if the length of pile embedment is 30 m assuming ground water table is far
below the ground surface. Use 8 = 0.80 and K = 1.5Ko.
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Figure Q2
A square pile group of 16 piles penetrates through a filled up soil of 3 m depth. The pile
diameter is 250 mm and pile spacing is 0.75 m. The unit cohesion of the material is 18
kN/m² and the unit weight of the soil is 15 kN/m². Compute the drag down force on the
group.
Determine the ultimate load capacity of a circular pile with diameter D = 20 cm installed in asaturated soft clay. The pile is embedded 10 m into the ground. According to measurements, thesoil exhibits an undrained shear strength according to the linear relationship: Su = 2+1.6z, wherez is the depth in meters and Su is the undrained shear strength in kPa. The soil's unit weight canbe assumed as 18 kN/m3
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Principles Of Foundation Engineering 9e
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- A 30 m long concrete pile is 305 mm times 350 mm in cross section and is fully embedded in a sand deposit. Using Broms' method, calculate the allowable lateral load Q_g (take FS = 2) at the ground level. Assume the pile is flexible and restrained. Let the soil unit weight, gamma = 16 kN/m^3, the soil friction angle, Phi' = 30^degree; and the yield stress of the pile material, F_y = 21 MPa,arrow_forwardA pile of diameter 0.4 m is fully embedded in a clay stratum having 5 layers, each 5 m thick as shown in the figure below. Assume a constant unit weight of soil as 18 kN/m³ for all the layers. Using method (= 0.15 for 25 m embedment length) and neglecting the end bearing component, the ultimate pile capacity (in kN) is G Y=18kN/m³- for all layers 7XXX 5m 5m 5m 5m 5m = 25 m 0.4m, c=40 kPa c=50 kPa c=60 kPa c=70 kPa c=80 kPa S XXXXarrow_forwardA group of 9 piles, 12 m long and 400 mm in diameter is arranged in a square pattern in homogeneous clay soil. The c/c spacing of the pile are 1000 mm. The properties of clay soil is given below Cc =0.10, e0=0.9, γsat = 20 kN/m^3, unconfined compressive strength qu= 70 kN/m^2 assume adhesion factor 0.7,. Water table is at GL. Determine the FOS against bearing if 1500 kN load is applied on the pile group and total settlement of pile group under the same loadarrow_forward
- A square group of 25 piles extends between depths of 2 m and 12 m in a deposit of 20 m thick stiff clay overlying rock. The piles are 0.5 m in diameter and are spaced at 1 m centre to centre in the group. The undrained shear strength of the clay at the pile base level is 180 kPa and the average value of the undrained shear strength over the depth of the pile is 110 kPa. The adhesion coefficient (a) is 0.45, FOS against shear failure is 3. Take No= 9. %3D When pile acting in a group Q,, Capacity of pile grouparrow_forward12.20 A 600 mm diameter and 25 m long driven concrete pile car- ries a column load of 1200 kN. It is estimated that the shaft carries 900 kN and the point carries 300 kN. Determine the settlement of the pile head using the Poulos and Davis method with the following data: E = 25 MN/m², Ep = 30,000 MN/m², and μ = 0.2arrow_forwardQuestions A group of 16 piles (4 in each row) was installed in a layered clay soil deposit shown below. The diameter of each pile is 500 mm and their c/c distance is 1m. The length of the pile group is 18m. Estimate the safe load capacity of the group with a factor of safety of 2.50. The adhesion factor (a) between the pile and soil in each soil layer are shown in the figure. 8 m 10 m C= 25 kPa;= 0°; a = 1.0 C₁= 40 kPa;p= 0; a = 0.7 TTTTTT Soil Profile O O O boor Plan View of pile grouparrow_forward
- A group of piles are arranged as shown in the figure. The piles are square in section with sides equal to 400 mm and has a spacing of 1.80 m on centers. One pile has a total length of 18 m. Unit weight of clay is 19.7 kN/m3 and has a cohesion of 90 kPa. Ground water table is located at depth of 20 m below the ground surface. Adhesion factor is 0.90. Determine the ultimate load – bearing capacity of the group of piles considering the piles acting individually.arrow_forwardA group pile has a section of 4 x 4 with each having a diameter of 305 mm are embedded in clay. The length of the piles are 12 m and the spacing between the piles (d) are 1.0 m. The recorded soil profile for the ground is shown in Table 1. Propose the allowable load bearing capacity of the pile with a factor of safety of (FS) of 3. (b) TABLE 1 : Soil type and soil parameter Depth Soil parameter 0.0 m to 2.0 m | Unit weight = 17.5 kN/m³ Cohesion = 20 kN/m? 2.0 m to 8.0 m Unit weight = 18.5 kN/m³ Cohesion = 60 kN/m? 8.0 m to 15.0 m Unit weight = 20.1 kN/m³ Cohesion = 80 kN/m?arrow_forwardA nine pile group consists of 0.30m diameter friction concrete piles 12m long. The piles are driven into clay having an unconfined compressive strength of 180kPa and the unit weight of clay is 18kN/m3. The spacing of piles is 0.75m center to center. Assuming a bearing capacity factor of Nc = 9, a= 1.0. Which of the following most nearly gives the minimum pile spacing in order to achieve 100% efficiency?arrow_forward
- 3. A concrete pile 15.24 m long having a cross section of 406 mm × 406 mm is fully embedded in a saturated clay layer for which Ysat 19.02 kN/m³, Ø = 0, and cu=76.7 kN/m². Determine the allowable load that the pile can carry (Assuming FS-3). Use the a method to estimate the skin friction and Vesic's method for point load estimation.arrow_forwardA frictional pile with a circular cross-section (diameter = D) is pushed into the soil %3D to a distance (L) and then it is subjected to an axial force (P) on its top end. Derive a formula to calculate the normal stress in any section x. P xx f N/mm2arrow_forwardSquare concrete piles are arranged in 5 row by 5 column formation beneath the pile cap. These piles are embedded into several layers of cohesive soil. The first layer is 3.75m deep and the second layer is 4.49m deep. The total depth of the third layer was not fully captured in the geotechnical report and is assumed to extend indefinitely. The piles are 0.60m wide. Each pile span 12.59m in length. The first layer has c = 61 kPa and α = 0.99. The second layer has c = 82 kPa and α = 0.78. The third layer has c = 81 kPa and α = 0.63. The bearing capacity factor Nc is equal to 8.What should be the spacing (m) to get a group efficiency of 111%? Consider ultimate capacities. Please answer this asap. For upvote. Thanksarrow_forward
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