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Das - Principles of Foundation Engineering SI 10/e (Homework)

James Finch

Engineering, section 1, Fall 2019

Instructor: Dr. Friendly

Current Score : 2 / 24

Due : Sunday, January 27, 2030 12:00 EST

Last Saved : n/a Saving...  ()

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  • Instructions

    A must-have resource for all foundation engineering courses, Das' PRINCIPLES OF FOUNDATION ENGINEERING (SI Edition), 10th Edition carefully balances current research with practical field applications as it introduces your civil engineering students to the core concepts and applications of foundation analysis design. Throughout this best-selling book, Dr. Das emphasizes how to develop the critical judgment civil engineers need to properly apply theories and analysis to the evaluation of soils and foundation design. A new chapter (Ch. 10) focuses on the uplift capacity of shallow foundations and helical anchors. This edition provides more worked-out examples and figures than any other book of its kind. New figures and updated worked-out examples accompany new learning objectives and illustrative photos to emphasize the skills most critical for students to master as successful civil engineers. WebAssign's customizable online resources further assist in reinforcing foundational skills.

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1. 1/2 points  |  Previous Answers DasPrincFoundEng10SI 4.2.001. My Notes
Question Part
Points
Submissions Used
1 2
1/1 0/1
2/100 5/100
Total
1/2
 
  • This exercise will let students review and reference question concepts.
  • Read It links are available as a learning tool under each question so students can quickly jump to the corresponding section of the eTextbook.
  • Students get just-in-time learning support with Watch It videos that contain narrated and closed-captioned videos walking students through the proper steps to solve a similar problem.

A sandy soil has maximum and minimum dry unit weights of 18.62 kN/m3 and 15.18 kN/m3, respectively, and a dry unit weight of compaction in the field of 16.81 kN/m3. Calculate the following.
(a)
the relative compaction in the field (in percent)
Correct: Your answer is correct. Your value is acceptable.%
(b)
the relative density in the field (in percent)
Incorrect: Your answer is incorrect.
Your response is within 10% of the correct value. This may be due to roundoff error, or you could have a mistake in your calculation. Carry out all intermediate results to at least four-digit accuracy to minimize roundoff error.%

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2. –/4 points DasPrincFoundEng10SI 4.3.002. My Notes
Question Part
Points
Submissions Used
1 2 3 4
–/1 –/1 –/1 –/1
0/100 0/100 0/100 0/100
Total
–/4
 
  • This exercise will let students review and reference question concepts.
  • Read It links are available as a learning tool under each question so students can quickly jump to the corresponding section of the eTextbook.
  • Students get just-in-time learning support with Watch It videos that contain narrated and closed-captioned videos walking students through the proper steps to solve a similar problem.

A silty clay soil has a plasticity index (PI) of 38. Use the following equations.
wopt(%) = (1.99 − 0.165 ln(E))(PI)
γd(max)(kN/m3) = L − Mwopt
where
L = 14.34 + 1.195 ln(E)
M = −0.19 + 0.073 ln(E)
Calculate the optimum moisture content (in percent) and the maximum dry unit weight of the soil (in kN/m3) for soil that has been compacted using the following tests.
(a)
the standard Proctor test
optimum moisture content % maximum dry unit weight kN/m3
(b)
the modified Proctor test
optimum moisture content % maximum dry unit weight kN/m3

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3. –/4 points DasPrincFoundEng10SI 4.3.003. My Notes
Question Part
Points
Submissions Used
1 2 3 4
–/1 –/1 –/1 –/1
0/100 0/100 0/100 0/100
Total
–/4
 
  • This exercise will let students review and reference question concepts.
  • Read It links are available as a learning tool under each question so students can quickly jump to the corresponding section of the eTextbook.
  • Students get just-in-time learning support with Watch It videos that contain narrated and closed-captioned videos walking students through the proper steps to solve a similar problem.

A silty clay soil has a plastic limit (PL) of 39. Use the following equations.
wopt(%) = (1.95 − 0.38 log10(E))(PL)
γd(max)(kN/m3) = 22.68e−0.0183wopt(%)
Calculate the optimum moisture content (in percent) and the maximum dry unit weight of the soil (in kN/m3) for soil that has been compacted using the following tests.
(a)
the standard Proctor test
optimum moisture content % maximum dry unit weight kN/m3
(b)
the modified Proctor test
optimum moisture content % maximum dry unit weight kN/m3

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4. –/1 points DasPrincFoundEng10SI 4.4.004. My Notes
Question Part
Points
Submissions Used
1
–/1
0/100
Total
–/1
 
  • This exercise will let students review and reference question concepts.
  • Read It links are available as a learning tool under each question so students can quickly jump to the corresponding section of the eTextbook.
  • Students get just-in-time learning support with Watch It videos that contain narrated and closed-captioned videos walking students through the proper steps to solve a similar problem.

The following are given for a natural soil deposit.
moist unit weight γ = 17.7 kN/m3 moisture content w = 14%
Gs
 = 2.7
This soil is to be excavated and transported to a construction site for use in a compacted fill. If the specification calls for the soil to be compacted at least to a dry unit weight of 18.6 kN/m3 at the same moisture content of 14%, how many cubic meters of soil from the excavation site are needed to produce 25,750 m3 of compacted fill?
m3

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5. 1/1 points  |  Previous Answers DasPrincFoundEng10SI 4.4.005. My Notes
Question Part
Points
Submissions Used
1
1/1
4/100
Total
1/1
 
  • This exercise will let students review and reference question concepts.
  • Read It links are available as a learning tool under each question so students can quickly jump to the corresponding section of the eTextbook.
  • Students get just-in-time learning support with Watch It videos that contain narrated and closed-captioned videos walking students through the proper steps to solve a similar problem.

A proposed embankment fill required 6,500 m3 of compacted soil. The void ratio of the compacted fill is specified to be 0.6. Four available borrow pits are shown below, along with the void ratios of the soil and the cost per cubic meter for moving the soil to the proposed construction site.
Borrow Pit Void Ratio Cost ($/m3)
A 0.96 8
B 0.84 9
C 0.78 11
D 0.90 7
Make the necessary calculations to select the pit from which the soil should be brought to minimize the cost. Assume
Gs
 to be the same for all borrow-pit soil.
     Correct: Your answer is correct.

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6. –/2 points DasPrincFoundEng10SI 4.6.006. My Notes
Question Part
Points
Submissions Used
1 2
–/1 –/1
0/100 0/100
Total
–/2
 
  • This exercise will let students review and reference question concepts.
  • Read It links are available as a learning tool under each question so students can quickly jump to the corresponding section of the eTextbook.
  • Students get just-in-time learning support with Watch It videos that contain narrated and closed-captioned videos walking students through the proper steps to solve a similar problem.

For a vibroflotation work, the backfill to be used has the following characteristics.
D50 = 2.4 mm
D20 = 0.66 mm
D10 = 0.61 mm
Determine the suitability number of the backfill.
How would you rate the material?
    

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7. –/2 points DasPrincFoundEng10SI 4.6.007. My Notes
Question Part
Points
Submissions Used
1 2
–/1 –/1
0/100 0/100
Total
–/2
 
  • This exercise will let students review and reference question concepts.
  • Read It links are available as a learning tool under each question so students can quickly jump to the corresponding section of the eTextbook.
  • Students get just-in-time learning support with Watch It videos that contain narrated and closed-captioned videos walking students through the proper steps to solve a similar problem.

For a vibroflotation work, the backfill to be used has the following characteristics.
D50 = 3.8 mm
D20 = 0.30 mm
D10 = 0.11 mm
Determine the suitability number of the backfill.
How would you rate the material?
    

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8. –/3 points DasPrincFoundEng10SI 4.8.008. My Notes
Question Part
Points
Submissions Used
1 2 3
–/1 –/1 –/1
0/100 0/100 0/100
Total
–/3
 
  • This exercise will let students review and reference question concepts.
  • Read It links are available as a learning tool under each question so students can quickly jump to the corresponding section of the eTextbook.

Consider the following figure.
A soil profile with three layers has an evenly distributed surcharge at ground level.
  • The top layer consists of sand with the groundwater table in the middle of the layer.
  • The middle layer consists of clay with thickness Hc.
  • The bottom layer consists of sand.
For a large fill operation, the average permanent load [Δσ′(p)] on the clay layer will increase by about 72 kN/m2. The average effective overburden pressure on the clay layer before the fill operation is 110 kN/m2. For the clay layer, which is normally consolidated and drained at top and bottom, the following values are given.
Hc = 8 m Cc = 0.27 eo = 1.02 cv = 0.52 m2/month
(a)
Determine the primary consolidation settlement of the clay layer (in m) caused by the addition of the permanent load Δσ′(p).
m
(b)
Determine the time required (in months) for 79% of primary consolidation settlement under the additional permanent load only. Use this table as necessary.
months
(c)
Determine the temporary surcharge, Δσ′(f) (in kN/m2) that will be required to eliminate the entire primary consolidation settlement in 12 months by the precompression technique. Use this figure as necessary.
kN/m2
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9. –/2 points DasPrincFoundEng10SI 4.9.010. My Notes
Question Part
Points
Submissions Used
1 2
–/1 –/1
0/100 0/100
Total
–/2
 
  • This exercise will let students review and reference question concepts.
  • Read It links are available as a learning tool under each question so students can quickly jump to the corresponding section of the eTextbook.
  • Students get just-in-time learning support with Watch It videos that contain narrated and closed-captioned videos walking students through the proper steps to solve a similar problem.

The diagram of a sand drain is shown in the figures below.
A sand drain is shown in section view and plan view.
  • The section view begins at the bottom with a sand layer, above that is a clay layer, and another sand layer above that.
    • The groundwater table comes to the middle of the top sand layer.
    • A surcharge is applied downward from the top.
    • Two vertical sand drains are shown going from the surface downward and ending at the top of the lower sand layer. These drains have radius rw and provide radial drainage.
    • Vertical drainage occurs between the sand drains.
    • The thickness of the clay layer is Hc.
  • The plan view shows that the sand drain is approximately hexagonal with an effective drainage diameter of de and radius rw. The drainage diameter is measured as the distance between midpoints of opposite sides.
Within a clay layer of thickness Hc a sand drain is shown with an effective drainage diameter of de (radius re). The sand drain has radius rw and is within a smeared zone. The radial distance from the center of the sand drain to the farthest point of the smeared zone is rs, where
rw < rs < re.
We are given the following.
rw
 = 0.27 m
rs
 = 0.37 m
de
 = 4.4 m
cv = cvr
 = 0.3 m2/month
kh⁄ks
 = 2
Hc
 = 9.1 m
Assume that the surcharge is applied instantaneously.
(a)
Determine the average degree of consolidation (in percent) for the clay layer caused only by the sand drains after six months of surcharge application.
%
(b)
Determine the average degree of consolidation (in percent) for the clay layer that is caused by the combination of vertical drainage (drained on top and bottom) and radial drainage after six months of the application of surcharge.
%

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10. –/3 points DasPrincFoundEng10SI 4.9.012. My Notes
Question Part
Points
Submissions Used
1 2 3
–/1 –/1 –/1
0/100 0/100 0/100
Total
–/3
 
  • This exercise will let students review and reference question concepts.
  • Read It links are available as a learning tool under each question so students can quickly jump to the corresponding section of the eTextbook.
  • Students get just-in-time learning support with Watch It videos that contain narrated and closed-captioned videos walking students through the proper steps to solve a similar problem.

Use any necessary data from the figure below.
Several curves are plotted on a coordinate plane, with horizontal axis Time factor Tv and vertical axis Degree of consolidation Uv(%). Each curve represents a different Tc value beginning on the left with Tc = 0 and increasing to Tc = 5 for the rightmost curve.
The curves go down and to the right ending at the x-axis. Curves with larger Tc have a steeper slope in the middle of the curve and flatter slope at the beginning and end of the curve than curves with lower Tc.
Some approximate points are given below for various values of Tc as (Tv, Uv).
  • for Tc = 0.04: (0.03, 8.035), (0.067, 24.21), (0.1, 31.83), (0.23, 51.61)
  • for Tc = 0.2: (0.2, 33.65), (0.24, 41.19), (0.3, 49.79), (0.42, 62.81)
  • for Tc = 1: (1, 69.46), (1.1, 76.47), (1.23, 82.95), (1.3, 85.66)
  • for Tc = 2: (2, 83.45), (2.13, 88.16), (2.2, 90.04), (2.3, 92.22)
For a sand drain project (see figure below),
A sand drain is shown in section view and plan view.
  • The section view begins at the bottom with a sand layer, above that is a clay layer, and another sand layer above that.
    • The groundwater table comes to the middle of the top sand layer.
    • A surcharge is applied downward from the top.
    • Two vertical sand drains are shown going from the surface downward and ending at the top of the lower sand layer. These drains have radius rw and provide radial drainage.
    • Vertical drainage occurs between the sand drains.
    • The thickness of the clay layer is Hc.
  • The plan view shows that the sand drain is approximately hexagonal with an effective drainage diameter of de (the distance between midpoints of opposite sides of the hexagon) and radius rw.
the following are given.
Clay: Normally consolidated
Hc
 = 3.35 m (one-way drainage)
Cc
 = 0.3
eo
 = 0.74
cv
 = 0.015 m2/day
Effective Overburden Pressure at the Middle of Clay Layer = 88 kN/m2
Sand Drain
rw
 = 0.07 m
rw
 =
rs
de
 = 2.8 m
cv
 =
cvr
A surcharge is applied as shown in the figure below.
A piecewise function is plotted on a coordinate plane, with horizontal axis Time (days) and vertical axis Surcharge (kN/m2). The function begins at the origin and goes up and right with constant slope to point (30, 70). The function then continues horizontally to the right.
Enter your value for Uv (in percent) from the table above.
%
Calculate the average degree of consolidation (in percent).
%
Calculate the consolidation settlement (in mm) 50 days after the beginning of the surcharge application.
mm

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