Principles of Geotechnical Engineering (MindTap Course List)
9th Edition
ISBN: 9781305970939
Author: Braja M. Das, Khaled Sobhan
Publisher: Cengage Learning
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Chapter 11, Problem 11.8P
To determine
Calculate the primary consolidation settlement of the clay due to the foundation load.
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Estimate the ultimate consolidation settlement under the centerline of a 15 X 15 m mat foundation. The mat is 1 m thick reinforced concrete and the average stress on the surface of the slab is 75 kPa. The soil profile is shown below. Oedometer tests on samples of the clay provide these average values.
’p = 130 kPa, Cc = 0.40, Cr = Cs = 0.03
Neglect any settlements due to the sand layer.
Please and thank you!! :)
75% consolidation in a laboratory test?
11.21 Refer to Figure 11.48. A square foundation, 2.5 × 2.5 m in size, supports a col-
umn load of 478 kN. The soil characteristics are given in the figure. Field moni-
toring indicated that the foundation settlement was 46 mm at the end of 2 years
a. Estimate the average stress increase in the clay layer due to the applied load.
b. Estimate the primary consolidation settlement.
c. What is the degree of consolidation after 2 years?
d. Estimate the coefficient of consolidation for the pressure range.
e. Estimate the settlement in 3 years.
478 kN
2.5 m x 2.5 m
1.5 m
Y = 16 kN/m
GWT
1.75 m
Yu = 18.8 kN/m³
w = 19%
G, = 2.71
LL = 37
3.5 m
o = 65 kN/m?
C,= 1/SC.
%3D
O Sand A Clay
Figure 11.48
SITUATION 2:
A normally consolidated clay layer 3m thíck has
a void ratio of 1.10. Liquid Limit is equal to 40
and the average effective stress on the clay
layer was 80 kPa. The average stress on it is
increased to 120 kPa as a result of construction
of a foundation.
13. Compute for the consolidation settlement
that will occur on the clay layer.
a. 17 mm
b. 45 mm
C. 68 mm
d. 57 mm
14. Compute for the consolidation settlement
that will occur on the clay layer if pre-
consolidation pressure is 96 kPa.
a. 68 mm
b. 57 mm
C. 17 mm
d. 45 mm
15. Compute for the consolidation settlement
that will occur on the clay layer if pre-
consolidation pressure is 130 kPa.
a. 45 mm
c. 57 mm
b. 68 mm
d. 17 mm
Chapter 11 Solutions
Principles of Geotechnical Engineering (MindTap Course List)
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- Redo Problem 11.6 using the weighted average method [Eq. (11.68)] to calculate the stress increase in the clay layer. Problem 11.6 Refer to Figure 11.43. Considering the soil to be a uniform clay layer, estimate the primary consolidation settlement due to the foundation load. Given: P = 150 kN; B = 3 m; L = 3 m; D, = 1.5 m; H = 8 m; e = 0.7; G, = 2.72; and LL = 42. Assume that the clay is normally consolidated, and the groundwater P table is at the foundation level. Use Ao = BL Figure 11.43 Foundation BxL Ao Soil H, = Poisson's ratio E, = modulus of elasticity H %3D Rock Figure 11.43 ©Cengage Leam ing 2014arrow_forwardA CD triaxial compression test conducted on a clay specimen revealed that c'=5 kPa and o'=22°. What is the major principal stress at failure if the confining pressure is 35 kPa? Solve the problem graphically and then analytically.arrow_forwardRefer to Figure 11.41. Given that B =1 m, L = 3 m, and Q = 110 kN, the soil characteristics given in the figure are Cs = 1/5 Cc, Ꝺ’c= 40 kN/m2. Field monitoring indicated that the foundation settlement was 19 mm during the first 12 months. a. Estimate the average stress increase in the clay layer due to the applied load. b. Estimate the primary consolidation settlement. c. What is the degree of consolidation after 12 months? d. Estimate the coefficient of consolidation for the pressure range. e. Estimate the settlement in 24 months. Answer must be: A. 6.33 B. 32.82 C. 57.89 D. 0.0013 E. 25.66arrow_forward
- A normally consolidated clay layer 3.65 m. thick has a void ratio of 1.09. Liquid limit is equal to 44 and the average effective stress on the clay layer was 79 kPa. The average stress on it is increased to 116 kPa. as result of the construction of a foundation. If the clay layer is preconsolidated, compute the consolidation settlement in millimeters if the preconsolidation pressure is 132 KPa. Use Cs = 1/6Cc.arrow_forwardA foundation with dimensions BxL supporting a column load, P. The foundation rests on a sandy soil underlain by a clay layer (consolidation test result in Problem 2). • Estimate the primary consolidation settlement of the clay due to the foundation load. • What is the void ratio at the end of primary consolidation? • Calculate the secondary Consolidation settlement after 6 years knowing that the primary consolidation settlement took 2.5 years. Given: P = 350 kN, B =L=2.5 m, Df= 2 m, H1= 3 m, and H2=4.5 m. The soil properties are as follows: Sand: ya = 16.4 kN/m³; ysat = 18.8 kN/m³ Clay: Ysat = 17.6 kN/m²; eo = 0.82, Ca=0.02 Sand D Yd H GWT BxL Ysat Clay Ysat Sandy gravelarrow_forwardRefer to Figure 11.41. Given that B =1 m, L = 3 m, and Q = 110 kN, the soil characteristics given in the figure are Cs = 1/5 Cc, Ꝺ’c= 40 kN/m2. Field monitoring indicated that the foundation settlement was 19 mm during the first 12 months. Estimate the average stress increase in the clay layer due to the applied load. Estimate the primary consolidation settlement. What is the degree of consolidation after 12 months? Estimate the coefficient of consolidation for the pressure range. Estimate the settlement in 24 months.arrow_forward
- Refer to Figure 5,determine th eaverage stress increase in the clay layer below the center of the foundation due to the net foundation load of 490,500kN (net load). Using Eq.(7.25)arrow_forward11.19 Refer to Figure 11.45. A square footing, 2 x 2 m in size, supports a column load of 300 kN. The soil characteristics are given in the figure. Field monitoring indi- cated that the foundation settlement was 19 mm during the first 12 months. a. Estimate the average stress increase in the clay layer due to the applied load. b. Estimate the primary consolidation settlement. c. What is the degree of consolidation after 12 months? d. Estimate the coefficient of consolidation for the pressure range. e. Estimate the settlement in 24 months. 300 kN 1m 2m x 2 m Ya = 14 kN/m3 I m Yu = 17 kN/m 24% G, = 2.74 LL = 46 2 m o'= 40 kN/m² C, = 1/5C. Sand Clay Figure 11.45 O Cengrge learring 2014arrow_forward2. Ten point load tests are carried out on cylindrical specimens of a sedimentary rock with 30 mm diameter, as shown in the figure. 50 mm The failure loads of these tests are equal to: 3.2, 4.1, 3, 3.8, 2.9, 4.2, 3.5, 3.6, 3.5 and 4 kiloNewtons. Determine Iyso of this rock. Predict the uniaxial compressive strength of this rock.arrow_forward
- Assume a buried stratum of clay 1.83 m thick will be subjected to a stress increase of 44.6 kPa at the center of the clay. The magnitude of the pre-construction soil overburden pressure P0= 48 kPa at the center of the clay layer. A laboratory compression test indicates that the clay has a pre-consolidation pressure of 72 kPa. The compression index is 0.30 and the value of the swell index is 0.05. The void ratio of clay is 1.50. a. Compute the settlement due to primary compression of clay.b. If full consolidation settlement will require approximately 8 years, compute the settlement due to secondary compression of clay over a period of 20-year time span. Assume secondary compression index 0.008.c. Estimate the total settlement to be expected over a 20-year time span considering the effect of secondary compressionNote: Draw Free Body- Diagram, Use 3 decimal Places Do not copy the one in chegg, it is incomplete Topic: Compressibility of Soil (Soil Mechanics)arrow_forwardIn a geotechnical laboratory an oedometer test on a saturated clay soil was conducted. The results in the laboratory report stated that the Cc = 0.2, Cr = 0.04 and OCR = 4.5. The existing vertical effective stress in the field was 130 kPa. A building foundation was designed to construct above the soil condition. This will increase the vertical stress at the center of the clay by 150 kPa. The thickness of the clay layer is 2 m and its water content is 28%. Solve the primary consolidation settlement and determine the difference in the settlement if OCR value were 1.5 instead 4.5.arrow_forwardA clay specimen with drained shear strength parameters of c'=5 kPa and Φ=320 is consolidated under all around pressure of 140 kPa.The specimen was then loaded axially to failure under undrained condition and failed when the principal stress diffrences reached 60 kPa.Calculate the pore pressure(u) and the pore pressure coefficient D(=A*B=Δu/Δσv) of the clay.arrow_forward
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