Chapter 15, Problem 15.8P

A braced cut is carried out to 10 m depth at a site where the soil consists of 4 m of sand ( = 17.0 kN/m3, = 33) at the top underlain by 6 m of clay ( = 18.5 kN/m3, c = 35 kN/m2). a. What would be the average value of cohesion and the unit weight for the equivalent homogeneous soil profile? b. Show the lateral earth pressure envelope you would use in determining the strut loads.

Determine the factor of safety against bottom heave for the braced cut described in Problem 15.18. Use Eqs. (15.66) and (15.70). For Eq. (15.70), assume the length of the cut, L = 18 m. 15.18 Refer to Figure 15.51 in which = 17.5 kN/m3, c = 60 kN/m2, and center-to-center spacing of struts is 5 m. Draw the earth pressure envelope and determine the strut loads at levels A, B, and C. FIG. 15.51

The elevation and plan of a bracing system for an open cut in sand are shown in Figure 14.21. Using Pecks empirical pressure diagrams, determine the design strut loads. Given: sand = 18 kN/m3, ' = 38, x = 3 m, z = 1.25 m, and s = 3 m.

A braced wall is shown in Figure 14.20. Given: H = 7 m, naH = 2.8 m, =30, =20, = 18 kN/m3, and c = 0. Determine the active thrust, Pa, on the wall using the general wedge theory. Figure 14.20

A braced cut shown in Figure P19.3 is to be made to a depth of 9.0 m in a saturated clay deposit where the unit weight is 17.65 kN/m3 and the undrained shear strength is 30 kN/m2. The struts are spaced horizontally at 3.0 m center to center. Find the strut loads.

Refer to Figure 15.27a. For the braced cut, H = 6 m, Hs = 2 m, s = 16.2 kN/m3, angle of friction of sand, s=34, Hc = 4 m, c = 17.5 kN/m3, and the unconfined compression strength of the clay layer, qu = 68 kN/m2. a. Estimate the average cohesion, cav, and the average unit weight, av, for development of the earth pressure envelope. b. Plot the earth pressure envelope. FIG. 15.27 Layered soils in braced cuts

A retaining wall 8 m high supports a cohesionless soil having a dry density of 1600 kg/m^3, angle of shearing resistance is 33 degrees and void ratio of 0.68. The surface of the soil is horizontal and level with top of the wall. Neglect wall friction and use Rankine’s formula for active pressure of a cohesionless soil. Determine the value of earth thrust on the wall per meter length if the soil is dry. a. 121 kN b. 186 kN c. 148 kN d. 137 kN   determine the value of earth thrust on the wall if water level is 3.5 m below the surface. a. 230 kN b. 250 kN c. 180 kN d. 210 kN   find the height above the base of the wall where the thrust acts during the water logged condition. a. 3.50 m b. 2.67 m c. 1.75 m d. 2.25 m

Determine the total active thrust, in kN/m, for a retaining wall (height 5.12 m.) with horizontal backfill given the following properties: Unit weight = 17.79 kN/m3, Angle of internal friction = 30°, Cohesion = 11.71 kPa, and Surcharge = 9.33 kPa.

Refer to the braced cut shown below. Given: unit weight = 17 kN/m3, Friction angle = 35degrees, and c = 0. The struts are located at 3 m center-to-center in the plan.  a.    Draw the earth-pressure envelope and determine the strut loads at levels A, B, and C. b.    Determine the sheet-pile section modulus c.    Determine the section modulus of the wales at level B Assume that   = 170 MN/m2.