Q3. Two meters of compacted fill (y= 20 kN/m³) is placed over a large area (Figure 4). A rectangular foundation of size 4 m x 5 m is constructed at the site with its base located at the existing ground surface. GWT is found at a depth of 3 m below the existing ground surface. a). Calculate and plot the in-situ vertical effective stress profile to a depth of 16 m below the existing ground surface prior to fill and footing placement. Use points with z = +2, +1, 0, -1, -2, -3, -5, -10, -13, -16 m (with z measured from the existing ground surface). b). Calculate and plot the additional effective stress due to the fill to a depth of 16 m. Use the same points as in part a). c). If the load applied on the foundation is 4 MN, calculate and plot the effective stress increase due to the footing to a depth of 16 m. Use the 2:1 approximate method and the same points as in part a). Summarize your calculations in an Excel spreadsheet and present sample calculations for z = 0, -3, -10 and -16 m (with z measured from the existing ground surface). All three vertical effective stress profiles should be shown on the same plot. Hint: the additional stress due to the fill will be constant with depth as the fill is placed over a large area. +Z -Z DI Bedrock Q = 4 MN 4 mx 5 m 3.0 m Fill y= 20 kN/m³ Sand y = 18 kN/m³ Ysat 19 kN/m³ Clay Ysat = 16 kN/m³ 2.0 m 10.0 m 6.0 m Figure 4. Stress increase due to the combined effect of backfill and footing

Principles of Foundation Engineering (MindTap Course List)
9th Edition
ISBN:9781337705028
Author:Braja M. Das, Nagaratnam Sivakugan
Publisher:Braja M. Das, Nagaratnam Sivakugan
Chapter10: Mat Foundations
Section: Chapter Questions
Problem 10.5P
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Q3. Two meters of compacted fill (y= 20 kN/m³) is placed over a large area (Figure 4). A
rectangular foundation of size 4 m x 5 m is constructed at the site with its base located
at the existing ground surface. GWT is found at a depth of 3 m below the existing
ground surface.
a). Calculate and plot the in-situ vertical effective stress profile to a depth of 16 m
below the existing ground surface prior to fill and footing placement. Use
points with z = +2, +1, 0, -1, -2, -3, -5, -10, -13, -16 m (with z measured from the
existing ground surface).
b). Calculate and plot the additional effective stress due to the fill to a depth of 16
m. Use the same points as in part a).
c). If the load applied on the foundation is 4 MN, calculate and plot the effective
stress increase due to the footing to a depth of 16 m. Use the 2:1 approximate
method and the same points as in part a).
Summarize your calculations in an Excel spreadsheet and present sample
calculations for z = 0, -3, -10 and -16 m (with z measured from the existing ground
surface). All three vertical effective stress profiles should be shown on the same plot.
Hint: the additional stress due to the fill will be constant with depth as the fill is placed
over a large area.
-Z
DI
Bedrock
Q = 4 MN
4 mx 5 m
3.0 m
Fill
y= 20 kN/m³
Sand
y = 18 kN/m³
Ysat 19 kN/m³
Clay
Ysat = 16 kN/m³
2.0 m
JA
10.0 m
6.0 m
Figure 4. Stress increase due to the combined effect of backfill and footing
Transcribed Image Text:Q3. Two meters of compacted fill (y= 20 kN/m³) is placed over a large area (Figure 4). A rectangular foundation of size 4 m x 5 m is constructed at the site with its base located at the existing ground surface. GWT is found at a depth of 3 m below the existing ground surface. a). Calculate and plot the in-situ vertical effective stress profile to a depth of 16 m below the existing ground surface prior to fill and footing placement. Use points with z = +2, +1, 0, -1, -2, -3, -5, -10, -13, -16 m (with z measured from the existing ground surface). b). Calculate and plot the additional effective stress due to the fill to a depth of 16 m. Use the same points as in part a). c). If the load applied on the foundation is 4 MN, calculate and plot the effective stress increase due to the footing to a depth of 16 m. Use the 2:1 approximate method and the same points as in part a). Summarize your calculations in an Excel spreadsheet and present sample calculations for z = 0, -3, -10 and -16 m (with z measured from the existing ground surface). All three vertical effective stress profiles should be shown on the same plot. Hint: the additional stress due to the fill will be constant with depth as the fill is placed over a large area. -Z DI Bedrock Q = 4 MN 4 mx 5 m 3.0 m Fill y= 20 kN/m³ Sand y = 18 kN/m³ Ysat 19 kN/m³ Clay Ysat = 16 kN/m³ 2.0 m JA 10.0 m 6.0 m Figure 4. Stress increase due to the combined effect of backfill and footing
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