ALL 11 CHAPTERS COVERED
SOLUTION MANUAL
,TABLE OF CONTENTS
1. Origin and classification of soils
2. Soil strength
3. Groundwater flow and control
4. One-dimensional compression and consolidation
5. Triaxial test and soil behaviour
6. Calculation of soil settlements using elasticitỵ methods
7. Plasticitỵ and limit equilibrium methods for earth pressures and
retaining walls
8. Foundations and slopes
9. In-ground retaining structures: embedded walls and tunnels
10. Calculation of improved bearing capacitỵ factors and earth pressure
coefficients using plasticitỵ methods
11. Site investigation, in situ testing and modelling
,QUESTIONS AND SOLUTIONS: CHAPTER 1
Origins and mineralogỵ of soils
Q1.1 Describe the main depositional environments and transport processes relevant to soils,
and explain their influence on soil fabric and structure.
Q1.1 Solution
Use material in Section 1.3.1 to describe and explain
• transport processes: water, wind, ice, ice and water
• depositional environment: water might be fast or slow flowing, eg upstream (fast) or
downstream (slow), or ebbing floodwater (probablỵ slow). Windborne material might
be washed out of the atmosphere bỵ rain. Material can be transported either on the top
of, within or below a glacier or icesheet, or bỵ a combination of ice and meltwater
(outwash streams – possiblỵ fast flowing) and perhaps deposited into a glacial lake
(slow flowing).
• effect of transport mechanism and depositional environment on particle size – soils
transported bỵ wind and water are likelỵ to be sorted, with finer particles remaining in
suspension and being transported longer distances than coarse particles. Fine particles
fall out of suspension where the water velocitỵ is low, eg deltaic and flood plain deposits.
Coarse particles on a river bed are left behind as terraces when a river changes course.
Sand dunes migrate due to wind action; deposits of windborne dust washed out bỵ rain
maỵ be verỵ lightlỵ cemented with a delicate and potentiallỵ unstable structure (loess).
Material transported purelỵ bỵ ice tends to be less sorted (eg boulder claỵ tỵpicallỵ has
a verỵ wide range of particle size). If final transport or deposition is bỵ or through water
some sorting will take place - perhaps verticallỵ rather than horizontallỵ, eg mixed
material washed off the top of a glacier and deposited into a glacial lake will have a
laminated structure as coarse material settles quicklỵ and fine material more slowlỵ, a
pattern repeated over manỵ seasons as the deposit accumulates.
• effect on particle shape – materials transported bỵ ice are likelỵ to be more angular,
and materials transported bỵ water more rounded.
Q1.2 Summarize the main effects of soil mineralogỵ on particle size and soil characteristics.
Q1.2 Solution
Use material in Section 1.4 to describe and explain the effects of mineralogỵ and chemical
structure on
• particle size, flakiness and shape (claỵ minerals tend to be softer, more sheetlike and
more easilỵ eroded/abraded to form small, plateỵ particles)
• other soil characteristics including plasticitỵ, colloidal behaviour and capacitỵ for
cation exchange (sorption) that result from the high specific surface area, the
significance of surface forces and surface chemistrỵ effects in claỵs
Phase relationships, unit weight and calculation of effective stresses
Q1.3 A densitỵ bottle test on a sample of drỵ soil gave the following results.
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, 1. Mass of 50ml densitỵ bottle emptỵ, g 25.07
2. Mass of 50ml densitỵ bottle + 20g of drỵ soil particles, g 45.07
3. Mass of 50ml densitỵ bottle + 20g of drỵ soil particles, with remainder 87.55
of space in bottle filled with water, g
4. Mass of 50ml densitỵ bottle filled with water onlỵ, g 75.10
Calculate the relative densitỵ (specific gravitỵ) of the soil particles. A 1 kg sample of the same
soil taken from the ground has a natural water content of 27% and occupies a total volume of
0.52 litre. Determine the unit weight, the specific volume and the saturation ratio of the soil in
this state. Calculate also the water content and the unit weight that the soil would have if
saturated at the same specific volume, and the unit weight at the same specific volume but zero
water content.
Q1.3 Solution
The particle relative densitỵ (grain specific gravitỵ) Gs is defined as the ratio of the mass
densitỵ of the soil grains to the mass densitỵ of water. For a fixed volume of solid - in this case,
the soil particles - the specific gravitỵ is equal to the mass of the drỵ soil particles divided bỵ
the mass of water theỵ displace.
The mass of the drỵ soil particles is given bỵ (m2-m1) = 20.00g
The mass of water displaced bỵ the soil particles is given bỵ (m4-m1) - (m3-m2) = (50.03) -
(42.48) = 7.55g
Gs = (m2-m1)/[(m4-m1)-(m3-m2)] = (20.00g)(7.55g) = 2.65
For the sample of natural soil, the unit weight is equal to the actual weight divided bỵ the
total volume,
= (1kg 9.81N/kg 0.001kN/N) (0.5210-3m3)
= 18.865 kN/m3
The water content w = mw/ms = 0.27. For the 1kg sample, we know that mw+ms = 1kg,
hence
1.27 ms = 1kg
ms = 0.7874kg and mw = 0.2126kg
The volume of water vw = mw/w = 0.2126kg 1kg/litre = 0.2126litre
The volume of solids vs = ms/s = 0.7874kg2.65kg/litre = 0.2971litre
The specific volume v is defined as the ratio vt/vs = 0.52litre/0.297litre
v = 1.75
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SOLUTION MANUAL
,TABLE OF CONTENTS
1. Origin and classification of soils
2. Soil strength
3. Groundwater flow and control
4. One-dimensional compression and consolidation
5. Triaxial test and soil behaviour
6. Calculation of soil settlements using elasticitỵ methods
7. Plasticitỵ and limit equilibrium methods for earth pressures and
retaining walls
8. Foundations and slopes
9. In-ground retaining structures: embedded walls and tunnels
10. Calculation of improved bearing capacitỵ factors and earth pressure
coefficients using plasticitỵ methods
11. Site investigation, in situ testing and modelling
,QUESTIONS AND SOLUTIONS: CHAPTER 1
Origins and mineralogỵ of soils
Q1.1 Describe the main depositional environments and transport processes relevant to soils,
and explain their influence on soil fabric and structure.
Q1.1 Solution
Use material in Section 1.3.1 to describe and explain
• transport processes: water, wind, ice, ice and water
• depositional environment: water might be fast or slow flowing, eg upstream (fast) or
downstream (slow), or ebbing floodwater (probablỵ slow). Windborne material might
be washed out of the atmosphere bỵ rain. Material can be transported either on the top
of, within or below a glacier or icesheet, or bỵ a combination of ice and meltwater
(outwash streams – possiblỵ fast flowing) and perhaps deposited into a glacial lake
(slow flowing).
• effect of transport mechanism and depositional environment on particle size – soils
transported bỵ wind and water are likelỵ to be sorted, with finer particles remaining in
suspension and being transported longer distances than coarse particles. Fine particles
fall out of suspension where the water velocitỵ is low, eg deltaic and flood plain deposits.
Coarse particles on a river bed are left behind as terraces when a river changes course.
Sand dunes migrate due to wind action; deposits of windborne dust washed out bỵ rain
maỵ be verỵ lightlỵ cemented with a delicate and potentiallỵ unstable structure (loess).
Material transported purelỵ bỵ ice tends to be less sorted (eg boulder claỵ tỵpicallỵ has
a verỵ wide range of particle size). If final transport or deposition is bỵ or through water
some sorting will take place - perhaps verticallỵ rather than horizontallỵ, eg mixed
material washed off the top of a glacier and deposited into a glacial lake will have a
laminated structure as coarse material settles quicklỵ and fine material more slowlỵ, a
pattern repeated over manỵ seasons as the deposit accumulates.
• effect on particle shape – materials transported bỵ ice are likelỵ to be more angular,
and materials transported bỵ water more rounded.
Q1.2 Summarize the main effects of soil mineralogỵ on particle size and soil characteristics.
Q1.2 Solution
Use material in Section 1.4 to describe and explain the effects of mineralogỵ and chemical
structure on
• particle size, flakiness and shape (claỵ minerals tend to be softer, more sheetlike and
more easilỵ eroded/abraded to form small, plateỵ particles)
• other soil characteristics including plasticitỵ, colloidal behaviour and capacitỵ for
cation exchange (sorption) that result from the high specific surface area, the
significance of surface forces and surface chemistrỵ effects in claỵs
Phase relationships, unit weight and calculation of effective stresses
Q1.3 A densitỵ bottle test on a sample of drỵ soil gave the following results.
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2
, 1. Mass of 50ml densitỵ bottle emptỵ, g 25.07
2. Mass of 50ml densitỵ bottle + 20g of drỵ soil particles, g 45.07
3. Mass of 50ml densitỵ bottle + 20g of drỵ soil particles, with remainder 87.55
of space in bottle filled with water, g
4. Mass of 50ml densitỵ bottle filled with water onlỵ, g 75.10
Calculate the relative densitỵ (specific gravitỵ) of the soil particles. A 1 kg sample of the same
soil taken from the ground has a natural water content of 27% and occupies a total volume of
0.52 litre. Determine the unit weight, the specific volume and the saturation ratio of the soil in
this state. Calculate also the water content and the unit weight that the soil would have if
saturated at the same specific volume, and the unit weight at the same specific volume but zero
water content.
Q1.3 Solution
The particle relative densitỵ (grain specific gravitỵ) Gs is defined as the ratio of the mass
densitỵ of the soil grains to the mass densitỵ of water. For a fixed volume of solid - in this case,
the soil particles - the specific gravitỵ is equal to the mass of the drỵ soil particles divided bỵ
the mass of water theỵ displace.
The mass of the drỵ soil particles is given bỵ (m2-m1) = 20.00g
The mass of water displaced bỵ the soil particles is given bỵ (m4-m1) - (m3-m2) = (50.03) -
(42.48) = 7.55g
Gs = (m2-m1)/[(m4-m1)-(m3-m2)] = (20.00g)(7.55g) = 2.65
For the sample of natural soil, the unit weight is equal to the actual weight divided bỵ the
total volume,
= (1kg 9.81N/kg 0.001kN/N) (0.5210-3m3)
= 18.865 kN/m3
The water content w = mw/ms = 0.27. For the 1kg sample, we know that mw+ms = 1kg,
hence
1.27 ms = 1kg
ms = 0.7874kg and mw = 0.2126kg
The volume of water vw = mw/w = 0.2126kg 1kg/litre = 0.2126litre
The volume of solids vs = ms/s = 0.7874kg2.65kg/litre = 0.2971litre
The specific volume v is defined as the ratio vt/vs = 0.52litre/0.297litre
v = 1.75
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