Concept explainers
(a)
Calculate the consolidation settlement inone year.
(a)
Answer to Problem 9.20CTP
The consolidation settlement in one year
Explanation of Solution
Given information:
The thickness of sand layer
The thickness of clay layer
The moisture content
The specific gravity of soil solids
The compression index
The coefficient of consolidation
The unit weight of sand is
The unit weight of fill
The depth of the compacted fill
Calculation:
Consider the unit weight of water
Calculate the initial void ratio
Substitute
Calculate the saturated unit weight
Substitute
At the middle of the clay layer:
Calculate the effective overburden pressure
Substitute
Calculate the increase in vertical pressure
Substitute
Calculate the final primary consolidation settlement
Substitute
Calculate the time factor
Substitute
Refer Table 9.3 “Variation of Time Factor with Degree of consolidation” in the Text Book.
Take the value of Uas
Take the value of Uas
Calculate the value of U for the value
Calculate the final consolidation settlement
Substitute
Therefore, the consolidation settlement in one year is
(b)
Plot the in situ variation of pore water pressure and effective stress with depth for the clay layer.
(b)
Explanation of Solution
Given information:
The thickness of sand layer
The thickness of clay layer
The moisture content
The specific gravity of soil solids
The compression index
The coefficient of consolidation
The unit weight of sand is
The unit weight of fill
The depth of the compacted fill
Calculation:
Calculate the total stress
Substitute
Calculate the pore water pressure
Substitute
Calculate the total stress
Substitute
Calculate the total stress
Substitute
Calculate the pore water pressure
Substitute
Calculate the total stress
Substitute
Show the variation of pore water pressure and effective stress with depth for the clay layer as in Figure 1.
(c)
Plot the variation of pore water pressure and effective stress with depth after on year.
(c)
Explanation of Solution
Given information:
The thickness of sand layer
The thickness of clay layer
The moisture content
The specific gravity of soil solids
The compression index
The coefficient of consolidation
The unit weight of sand is
The unit weight of fill
The depth of the compacted fill
Calculation:
Consider the degree of consolidation
Refer to part (a).
The time factor
Calculate the effective stress
Substitute
Calculate the pore water
Substitute
Calculate the ratio of height of soil to the maximum drainage depth as shown below.
Substitute
Refer Figure 9.20 “Variation of
Take the value of
Calculate the effective stress
Substitute
Calculate the pore water
Substitute
At the bottom of the clay layer, after one year:
Calculate the ratio of height of soil to the maximum drainage depth;
Substitute
Refer Figure 9.20 “Variation of
Take the value of
Calculate the effective stress
Substitute
Calculate the pore water
Substitute
Show the variation of the pore water pressure and the effective stress with depth as in Figure 1.
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Chapter 9 Solutions
Fundamentals of Geotechnical Engineering (MindTap Course List)
- For a normally consolidated soil, the following is given: Determine the following: a. The compression index, Cc. b. The void ratio corresponding to pressure of 200 kN/m2arrow_forward2.9 A normally consolidated clay has the following values. Void ratio, e k (cm/sec) 0.2 × 10 0.91 x 10-6 1.2 1.9 Estimate the magnitude of k of the clay at a void ratio (e) of 0,9. Use Eq. (2,41).arrow_forwardThe following data are given for normally consolidated clay: Thickness=2.6m Primary Cc=0.3 Secondary Cc=0.02 e=0.8 Average Pressure=127 kPa Change in pressure (vertical) =46 kPa Determine the following 1. Primary Consolidation Settlement (Ans. 58.17mm) 2. Secondary Settlement five years after the completion of the primary settlement. The time for completion of primary settlement is 1.5 years. (Ans. 15.4mm)arrow_forward
- 5. For the soil profile given below, assume that the primary consolidation settlement for the clay layer is completed in 3 years. Estimate the secondary consolidation settlement for the clay layer at the end of 10 years. Yw= 10kN/m³, Ca = 0.03 1m 1.5m 2m Groundwater table 0.5m BXL = 2m x 4m Sand y = 17.0 kN/m³ 90 = 100kPa Sand Ysat = 19.0 kN/m² Normally consolidated Clay Ysat = 20 kN/m³ eo = 0.7 Cs = 0.09 Cc = 0.2 -arrow_forwardRefer to Figure below. Estimate the primary consolidation settlement in the clay layer. Given: Δσ = 150 kN/m2; H1 = 3 m; H2 = 4 m; and H3= 5 m. Soil characteristics are as follows: • Sand: γdry = 15 kN/m3, γsat = 19 kN/m3 • Clay: LL = 65; e = 0.65; γsat = 18 kN/m3; ; Cs =1/6cc σʹc = 200 kN/m2arrow_forward4. In a consolidated-drained triaxial test on a clay that is normally consolidated, the results are as follows: O3 = 15 lb/in 2 (Aoa)f = 11 lb/in? (Aua)f = 7.2 lb/in? a) Determine the consolidated-undrained friction angle. %3D b) Calculate the drained friction angle.arrow_forward
- 11.12 A 2-m clay layer in the field has a current effective stress, oó= 70 kN/m?. There is a net stress increase, Ao = 180 kN/m², due to a foundation load. Calculate the expected primary consolidation settlement. The results of a consolidation test on the clay are given below. o' (kN/m) 0.98 12 0.94 50 0.82 200 0.73 400 ©Cngage lamng 2014arrow_forwardFor a given consolidated clay: Gs= 2.71; LL= 45; In situ average effective overburden pressure = 120 kPa; In situ void ratio= 0.80 ; Thickness of clay layer = 4m ; average increase of effective stress on clay layer= 40 kPa; Effective pressure at the mid-height of clay layer= 60 kPa; Swell Index (Cs)= 1/5 Cc. Compute the compression index. a.0.534 b.0.513 c.0.315 d.0.145 With Free Body Diagramarrow_forwardFor the soil profile given below, assume that the primary consolidation settlement for the clay layer is completed in 3 years. Estimate the secondary consolidation settlement for the clay layer at the end of 10 years. Yw= 10kN/m³, Ca= 0.03 1m 1.5m 2m BxL= 2m x 4m Groundwater table 0.5m 90 = 100kPa Sand y = 17.0 kN/m³ Sand Ysat 19.0 kN/m³ a retaining wall are shown in Normally consolidated Clay Ysat 20 kN/m³ eo = 0.7 Cs=0.09 Cc = 0.2arrow_forward
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