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All Textbook Solutions for Fundamentals of Geotechnical Engineering (MindTap Course List)
18.8PDetermine the maximum load that can be allowed on a 500 mm diameter and 18 m long pile driven into a clay where = 20.0 kN/m3 and cu = 60 kN/m2. Use the a method for determining the skin friction. Allow a factor of safety of 3. What percentage of the ultimate load is being carried by the pile shaft?18.10PRedo Problem 18.10 using the method for estimating the skin resistance. 18.10 A concrete pile 15 m long with a cross section of 380 mm 380 mm is fully embedded in a saturated clay layer. For the clay, sat = 18 kN/m3, = 0, and cu = 80 kN/m2. Assume that the water table lies below the tip of the pile. Determine the allowable load that the pile can carry (FS = 3). Use the a method to estimate the skin resistance.Determine the maximum load that can be allowed on the 450 mm diameter pile shown in Figure 18.36, with a safety factor of 3. Use the a method for computing the shaft friction. FIG. 18.3618.13PA 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).A concrete pile is 18 m long and has a cross section of 405 mm 405 mm. The pile is embedded in sand having = 17.5 kN/m3 and = 36. The allowable working load is 650 kN. If 450 kN are contributed by the frictional resistance and 200 kN are from the point load, determine the elastic settlement of the pile. Here, Ep = 21 106 kN/m2, Es = 28 103 kN/m2, s = 0.4.and = 0.6.18.16P18.17P18.18P18.19PFigure 18.26a shows a pile. Let L = 20 m, D = 450 mm. Hf = 4m, f = 17.5 kN/m3, fill = 25. Determine the total downward drag force on the pile. Assume that the fill is located above the water table and that = 0.5 fill. FIG. 18.26 Negative skin frictionRefer 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 friction18.22PFigure 18.39 shows a 3 5 pile group consisting of 16 concrete piles of 400 mm diameter and 12 m in length. What would be the maximum load that can be allowed on the mat with a factor of safety of 3? The piles have center-to-center spacing of 1200 mm. FIG. 18.39The section of a 4 4 group pile in a layered saturated clay is shown in Figure 18.40. The piles are square in cross section (356 mm 356 mm). FIG. 18.40 The center-to-center spacing of the piles, d, is 850 mm. Assuming that the groundwater table is located 3 m below the pile tip, determine the allowable load-bearing capacity of the pile group. Use FS = 4.18.25P18.26CTP19.1P19.2PRedo Problem 19.2. Use Eq. (19.4) and Es = 600 pa. 19.2 A drilled shaft is shown in Figure 19.14. For the shaft, L1 = 6 m, L2 = 3 m, Ds = 1.2 m, and Db = 2 m. For the soil, c = 15.6 kN/m3, cu = 35 kN/m2, s = 17.6 kN/m3, and =35. Determine the net allowable point bearing capacity (FS = 3). Use Eq. (19.17) FIG. 19.14For the drilled shaft described in Problem 19.2, what skin resistance would develop for the top 6 m, which is in clay? Use Eqs. (19.26) and (19.28) 19.2 A drilled shaft is shown in Figure 19.14. For the shaft, L1 = 6 m, L2 = 3 m, Ds = 1.2 m, and Db = 2 m. For the soil, c = 15.6 kN/m3, cu = 35 kN/m2, s = 17.6 kN/m3, and =35. Determine the net allowable point bearing capacity (FS = 3). Use Eq. (19.17) FIG. 19.1419.5P19.6P19.7PFor 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. 19.16For 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. 19.1619.10P19.11CTP20.1P20.2PRepeat Problem 20.2 based on limit state design, using the factors given in Table 20.4. 20.2 A continuous foundation is required in a soil where c = 10 kN/m2, =26 and = 19.0 kN/m3. The depth of the foundation will be 1.0 m. The dead load and the live load are 600 kN/m and 400 kN/m, respectively. Determine the required width for the foundation based on allowable stress design with FS = 3, using Eq. (16.3) and Table 16.1.Repeat Problem 20.2 based on LRFD using the following factors. Load factor for dead load = 1.25 Load factor for live load = 1.75 Strength reduction factor on the ultimate bearing capacity = 0.50 20.2 A continuous foundation is required in a soil where c = 10 kN/m2, =26 and = 19.0 kN/m3. The depth of the foundation will be 1.0 m. The dead load and the live load are 600 kN/m and 400 kN/m, respectively. Determine the required width for the foundation based on allowable stress design with FS = 3, using Eq. (16.3) and Table 16.1.