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(a)
State whether the statement “drilled shafts also include large diameter driven piles” is true or false.
(a)
Answer to Problem 19.1P
The given statement is
Explanation of Solution
The drilled shafts are cylindrical and deep; cast-in-place concrete foundations are poured in these shafts and by drilling process; whereas driven piles are commonly driven into the ground in situ.
Hence, the drilled shafts do not include large diameter of driven piles.
Therefore, the given statement is
(b)
State whether the statement “drilled shafts can be 500 mm in diameter” is true or false.
(b)
Answer to Problem 19.1P
The given statement is
Explanation of Solution
The drilled shaft diameter can range from 2 ft (609.6 mm) to 30 feet (9,144 mm). Thus, the drilled shafts cannot be in diameter of 500 mm.
Therefore, the given statement is
(c)
State whether the statement “adhesion factor
(c)
Answer to Problem 19.1P
The given statement is
Explanation of Solution
The adhesion factor for stiff clays can range from 0.3 to 0.45, and the larger value of adhesion factor is used for soft clay due to its more unit skin friction.
Therefore, the given statement is
(d)
State whether “drilled shafts in sands derive most of their load carrying capacity from the point resistance than the skin friction” is true or false.
(d)
Answer to Problem 19.1P
The given statement is
Explanation of Solution
The drilled shafts’ capacity is developed from the combination of end bearing and side shear. The side shear is correlated to the soil shear strength and in sands, the friction is less.
Therefore, the given statement is
(e)
State whether the statement “when the settlement is 1% of the drilled shaft diameter, greater fraction of skin friction is mobilized than the point load in sands and clays” is true or false.
(e)
Answer to Problem 19.1P
The given statement is
Explanation of Solution
The arrangement of sands and clays was done during the initial drilling process rather than the end point. When 1% of settlement is achieved, the soil which is around the shaft gets mobilized much earlier than the end point.
Therefore, the given statement is
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Chapter 19 Solutions
Fundamentals of Geotechnical Engineering (MindTap Course List)
- For the drilled shaft described in Problem 19.7, estimate the total elastic settlement at working load. Use Eqs. (18.45), (18.47), and (18.48). Assume that Ep = 20 106 kN/m2, s = 0.3, Es = 12 103 kN/m2, = 0.65 and Cp = 0.03. Assume 80% mobilization of skin resistance at working load. (See Part c of Problem 19.7) 19.7 Figure 19.16 shows a drilled shaft without a bell. Here, L1 = 6 m, L2 = 7 m, Ds = 1.5 m, cu(1) = 50 kN/m2, and cu(2) = 75 kN/m2. Find these values: a. The net ultimate point bearing capacity. Use Eqs. (19.23) and (19.24) b. The ultimate skin resistance. Use Eqs. (19.26) and (19.28) c. The working load, Qw (FS = 3) FIG. 19.16arrow_forwardFor the drilled shaft described in Problem 19.7, determine these values: a. The ultimate load-carrying capacity b. The load-carrying capacity for a settlement of 25 mm Use the procedure outlined in Section 19.8. 19.7 Figure 19.16 shows a drilled shaft without a bell. Here, L1 = 6 m, L2 = 7 m, Ds = 1.5 m, cu(1) = 50 kN/m2, and cu(2) = 75 kN/m2. Find these values: a. The net ultimate point bearing capacity. Use Eqs. (19.23) and (19.24) b. The ultimate skin resistance. Use Eqs. (19.26) and (19.28) c. The working load, Qw (FS = 3) FIG. 19.16arrow_forwardIn Problem 18.4, find the maximum bending moment in the sheet pile and determine the required section modulus, assuming an allowable stress of 190 MN/m2. 18.4 Refer to Figure 18.13. Given L1 = 1.5 m, L2 = 3 m; for the sand, =33, =16.5kN/m3, sat=19.0kN/m3; and, for the clay, c=50kN/m2, =0, sat=20kN/m3. Determine the depth of sheet pile required, allowing for a 50% increase from the theoretical estimate.arrow_forward
- Refer to Figure 18.26b. Let L = 15.24 m, fill = 17.29 kN/m3, sat(clay) = 19.49 kN/m3, clay = 20, Hf = 3.05 m, and D = 0.406 m. The water table coincides with the top of the clay layer. Determine the total downward drag on the pile. Assume that = 0.6 clay. FIG. 18.26 Negative skin frictionarrow_forward(a) A pit of 6.4 m deep is to be excavated in a fine sand stratum completely saturated up to the ground surface. The saturated unit weight of the sand was obtained as 20.3 kN/m3. To stabilize the bottom of the excavation (pr o stabilize the bottom of the excavation (prevent boiling), it was decided to drive steel sheet piles to act as cutoff walls that encircle the excavation. decided to drive steel sheet piles to act as cutoff walls that encircle the excavation. Determine the total length of sheet pile wall to provide a factor of safety of 1.5 against sand boiling. Assume specific gravity of soil, against sand boiling. Assume specific gravity of soil, Gs= 2.7 and unit weight of water, γw = 9.81 kN/m3arrow_forwardRefer to Figure 9.42b. Let L = 18 m, γfill = 17 kN/m3, γsat(clay) = 19.8 kN/m3, Φ'clay = 20°, Hf = 3.5 m, and D (pile diameter) = 406 mm. The water table coincides with the top of the clay layer. Determine the total downward drag force on the pile. Assume ẟ' = 0.6 Φ'clay.arrow_forward
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