Two meters below the ground surface, a 2x2 m square footing is constructed on NC clayey sand. The layer is subjected to a CPT test, with the results revealing an average cone resistance of 20 Mpa. A layer of hard rock is laid 20 meters below the surface. The service load of 25 ton.f is acting on the footing column. Find the elastic settlement using the generalized elastic method. The water level is at the surface and you can use yw 10 KN/m3. (footing weight is negligible) Hint: use table 4.8 of textbook to find the undrained modulus. TABLE 4.8 ESTIMATING EQUIVALENT SOIL MODULUS, ES, VALUES FROM CPT RESULTS [Adapted from Schmertmann et al. (1978), Robertson and Campanella (1989), and other sources.] USCS Group Symbol Soil Type SW or SP Young, normally consolidated clean silica sands (age < 100 years) Aged, normally consolidated clean silica sands (age > 3,000 years) Overconsolidated clean silica sands SW or SP SW or SP SM or SC SM or SC Normally consolidated silty or clayey sands Overconsolidated silty or clayey sands Esla 2.5-3.5 3.5-6.0 6.0-10.0 1.5 3

Two meters below the ground surface, a 2x2 m square footing is constructed on NC clayey sand. The layer is subjected to a CPT test, with the results revealing an average cone resistance of 20 Mpa. A layer of hard rock is laid 20 meters below the surface. The service load of 25 ton.f is acting on the footing column. Find the elastic settlement using the generalized elastic method. The water level is at the surface and you can use yw 10 KN/m3. (footing weight is negligible) Hint: use table 4.8 of textbook to find the undrained modulus. TABLE 4.8 ESTIMATING EQUIVALENT SOIL MODULUS, ES, VALUES FROM CPT RESULTS [Adapted from Schmertmann et al. (1978), Robertson and Campanella (1989), and other sources.] USCS Group Symbol Soil Type SW or SP Young, normally consolidated clean silica sands (age < 100 years) Aged, normally consolidated clean silica sands (age > 3,000 years) Overconsolidated clean silica sands SW or SP SW or SP SM or SC SM or SC Normally consolidated silty or clayey sands Overconsolidated silty or clayey sands Esla 2.5-3.5 3.5-6.0 6.0-10.0 1.5 3

Structural Analysis

6th Edition

ISBN:9781337630931

Author:KASSIMALI, Aslam.

Publisher:KASSIMALI, Aslam.

Chapter2: Loads On Structures

Section: Chapter Questions

Problem 1P

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A 100'x50' mat foundation (also called slab-on-grade) will be placed at the site shown in Figure 1. Calculations show that the foundation will cause an average increase in vertical stress in the clay layer of (a) 850 psf under the foundation center, and (b) 350 psf under the foundation corner. Find the foundation settlement due to the consolidation of the clay layer both at the foundation center and the foundation corner. Can the resultant differential settlement be considered tolerable? Sand Clay Bedrock 2.5 ft 5 ft 5 ft 7-100pcf 122.5pcf, eo=1, op=1000psf Cc-0.5, Cs-C-0.1 Figure 1.
Q1/ The results of a load test carried out on a plate of size 30 cm x 30 cm are given in Table below. The load test was carried out at a depth of 2.5 m, below ground surface. The soil profile is fairly homogeneous sand at the site. From the test results: a. determine the settlement of an actual foundation of size 2.5 m x 2.5 m carrying a total load of 155 ton and located at a depth of 2.5 m below the ground surface. b. What is the bearing capacity of foundation if the settlement of plate 12.6 mm. * Load intensity 0.496 0.992 1.488 1.984 2.48 2976 3.472 3.968 4.464 496 kg/cm² Settlement, 0.5 1.0 1.8 2.75 44 54 9.8 125 17.0 28.7 mm
2- Determine the stress increase below the center of the footing using both theoretical and approximate methods at the top, middle and bottom of the clay layer. In addition, determine the average stress increase for the clay layer. Dimensions in Heights in m Unit weights in kN/m3 kN m P2 H1 H2 H3 BL Hw 2.5 Yoati 18.0 19.0 3.0 3.0 2.0 16.0 2 3 1174 Load - 0 Hw H1 H2 H3 OSand Clay (hoemally conactiduted)
Q1/ The results of a load test carried out on a plate of size 30 cm x 30 cm are given in Table below. The load test was carried out at a depth of 2.5 m, below ground surface. The soil profile is fairly homogeneous sand at the site. From the test results: a. determine the settlement of an actual foundation of size 2.5 m x 2.5 m carrying a total load of 155 ton and located at a depth of 2.5 m below the ground surface. b. What is the bearing capacity of foundation if the settlement of plate 12.6 mm. Load intensity 0.496 0.992 1.488 1.984 2.48 2.976 3.472 3.968 4.464 496 kg/em Settlement, 0.5 1.0 1.8 2.75 4.4 5.4 9.8 12.5 17.0 28.7 mm
Calculate the settlement of the 10-ft-thick clay layer that will result from the load carried by a 5-ft-square footing. The clay is normally consolidated. Use the 2:1 method to calculate the average increase of effective pressure in the clay layer. 10 ft 10 ft 10 ft 5 ft ↓ Dry sand Footing size 5 ft x 5ft Sand Clay Ydry = 100 pcf Groundwater table Ysat = 120 pcf Ysat = 110 pcf % = 1.0 LL=40
The figure below shows a proposed foundation site, with 10 ft of sand overlying 20 ft of clay with consolidation properties shown. The clay is normally consolidated. Assume 1-D conditions.a. Compute the initial σ′v at the middle of the clay layer prior to excavation and constructionb. After excavation and during construction, the foundation area will be heavily loaded with the structure and equipment so that σ′v at the middle of the clay layer will be increased to 3900 psf. Determine the settlement that will occur under these conditionsc. After construction is completed, the equipment will be removed and the final σ′v at the middle of the clay layer will be 3200 psf. Compute the swell that occurs after the equipment is removed
A 1.2 meter wide long (strip) footing carries a wall loading of 48 kN per meter of wall length. What vertical stress increase results below the center of the footing at depths of 1 meter, 2 meter, and 4 meter, assuming: (a) Boussinesq conditions apply.(b) Westergaard conditions apply. (c) Show all work
The following results were obtained from CU tests on a clay soil that is the foundation material for an embankment. 03 (kPa) 300 400 600 0₁-03 (kPa) 331 420 487 Au (kPa) 111 160 322 (a) Determine the total and effective principal stresses for all three tests (You may summarize them in a table). (b) Recommend the shear strength parameters to be used for short-term and long-term analyses. The maximum confining pressure (cell pressure) at the depth of interest is 300 kPa. (Note: the clay is a normally consolidated one).
A circular footing with a radius of r = 4.0 ft will be embedded D = 2 ft in uniform clay. The top of the foundation is at the surface. The water table is at the ground surface. An intact sample of the clay with Gs=2.75 was obtained using a thin-walled Shelby tube from a depth of 10 ft below the ground surface. The sample was saturated and has a gravimetric water content of 45 %. Estimate its void ratio e0 and total unit weight y _in pcf. Ovp' = 800psf Void Ratio 1.5 1.4 1.3 1.2 1.1 1.0 0.9 0.8 do 10 0.1 0 2 z/r, depth in radii 6 7 8 9 Cr = 0.07 100 1000 Effective Stress (psf) 0.2 0.3 0.4 0.6 0.81.0 7.0 10.0 Cc = 0.3 8.0 9.0 5.0 6.0 I, stress in percent of surface contact pressure 2 3456 8.10 10000 3.0 2.5 (2.0) 1.25 20 30 40 50 60 80 100 1.0 PAG 0.75 Note: Numbers on curves indicate offset distances in radii, x/r. 2r Z 0.5 0₂- KAB X 0.25 IX q 100 0, 10 FIGURE 4.10 Chart for calculating the increase in vertical stress beneath a uniformly loaded circular area. (From NAVFAC DM-7.1, 1982,…
layer. 2. A project with excavation and construction stages will take place at your site. The profile contains a saturated clay On March 1, the effective stress at point A (in the middle of the clay layer) is 150 kPa, and the overconsolidation ratio is 1. On April 1, the effective stress at point A is 140 kPa. On May 1, the effective overconsolidation ratio on May 1? Show your work and circle your answer. stress at point A is 290 kPa. What is the
2. A 2m X 2m footing carrying 1400KN load is constructed in a site with 2.5m thick clay layer under a 2.5m thick sand layer. If the footing and the ground water table are located at 1.5m below the surface, calculate the consolidation settlement of the footing. You may assume the following soil properties: for sand sat 15.7kN/m°, and for clay eo= 0.65, Cc = 0.25, Cs = 0.06, O'p = 200kN/m² and sat =19.25KN/m³. 19.25kN/m and t = %3D
Calculate: a.) The unit weight of soil at a depth of 3m below the ground surface. b.) The normal stress of soil at a depth of 3m below the ground surface. c.) The potential shear strength of the soil at a depth of 3m below the ground surface when the water table is at a depth of 3.5m and the soil is cohesionless. d.) The modified value of the shear strength if the water table reaches the ground surface. e.) The modified value of the shear strength if the water table reaches the ground surface but the soil has a cohesion of 12 kPa.