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BTEC Higher National Diploma in Civil Engineering MT/Bsc Civil/04/33
A.A.M.ASAM Page 1
Task 1 Engineering Geology (P1)
a) List the main types of rock according to their mode of formation.
In geology, a rock is a naturally occurring solid aggregate of one or more minerals or
mineralogist. For example, the common rock, granite, is a combination of the quartz, feldspar
and biotitic minerals. The Earth's outer solid layer, the lithosphere, is made of rock.
Rocks have been used by mankind through out history. From the Stone Age rocks have been
used for tools. The minerals and metals we find in rocks have been essential to human
civilization.[1]
Three major groups of rocks are defined: igneous, sedimentary, and metamorphic. The scientific
study of rocks is called petrology, which is an essential component of geology.
There are three basic types of rocks according to the mode of formation.
Igneous Rock
Sedimentary Rock
Metamorphic Rock
Igneous: these are rocks that solidified directly from molten silicates, which geologists
call magma. Igneous rock is formed by magma (molten rock) being cooled and becoming
solid. They may form with or without crystallization, either below the surface as intrusive
(plutonic) rocks or on the surface as extrusive (volcanic) rocks
Examples are: granite, basalt, pumice and flint (which is a form of quartz).
Sedimentary: these are formed when igneous rocks are eroded as a sediment under the
sea. Sedimentary rock is formed by deposition and consolidation of mineral and organic
material and from precipitation of minerals from solution. The processes that form
sedimentary rock occur at the surface of the Earth and within bodies of water.Fossils are
often found in this layer.
Examples are limestone, chalk, sandstone.
Metamorphic: Any of a class of rocks that result from the alteration of preexisting rocks
in response to changing geological conditions, including variations in temperature,
pressure, and mechanical stress. The preexisting rocks may be igneous, sedimentary, or
other metamorphic rocks.
Examples are: slate, marble, quartzite.
BTEC Higher National Diploma in Civil Engineering MT/Bsc Civil/04/33
A.A.M.ASAM Page 2
Task - 1
b) List the main types of soil based on their mode of transportation and deposition.
Types of soil
The types of soils can be presented in different forms which are shown below:-
Transported soils
Any soil that has been transported from its place of origin by wind, water or ice or any other agency and has been redeposit is called transported soil. These soils are more common as
compared to residual soils. The particles features such as size, shape, and texture of transported
soils depends on source by which they were transported. These soils can further be categorized
as alluvial, Lacustrine, Marine, Aeolian and Glacial deposits.
Residual soils
There is no specific or particular definition for residual soils, however all the definitions that are
in literature do indicate that these soils are formed on site as a result of weathering of rocks and
they remain at that same place.
Soils which are formed by weathering of rocks may remain in position at the place of region. Theses soils are found at large scale in area where the climate is hot and humid and cause the
weathering of rocks easily. The sizes of grains of these soils are not specific and may break into
smaller pieces by small amount of load.
So it can be conclude that soils which remain at the place where they were created from
weathering of rocks are known as residual soils and the soils which are moved or blown from
their original place of formation by different activities are transported soils.
Types of soils based on texture
Soil texture refers to the particle size of each mineral present in soil. It also includes the
proportion of each particle size in soil. Based on soil texture, the soils can be divided into three
types sand silt and clay.
Sand
The particle size for sand is considered to be largest as compared to other types. Most
classification systems considers the particle size of sand from 2mm to 0.05mm in diameter. The
soils which consists of high proportion of sandy particles is known as sandy soils
BTEC Higher National Diploma in Civil Engineering MT/Bsc Civil/04/33
A.A.M.ASAM Page 3
Clay
Clay consists of particle size lesser then 0.002mm.The soil which contains higher proportion of
clay particles is known as clayey.
Silt
The particle size for silt is considered to be from 0.05mm to 0.002mm or in some countries it
also taken as 0.02mm.However in case of silt the soil containing higher proportion of silt are
considered as loamy soils.
The loamy soils are further divided into different types based on proportion of clay, sand and slit
particles. Soils with sand and silt particles in higher proportion is called sandy loams or loamy
sands. Clayey particles in majority result in sandy clay loam or sandy clay. The soil containing
approximately the same quantity of clay, sand and silt particles is considered as clay loam.
Soil Components
The ideal soil consists of 50% solid particles, the solid part may consist of up to 5% of organic
matters. The rest of 50% is shared equally among air and water contents which cover 25% each
in soil composition.
Water
Water makes up 25% of soil composition in ideal situation. The amount of water can vary based
on conditions. In fully dry condition the water content is less as compared to saturated
conditions.
Air
Air is 25% of soil composition. Like water the air content also changes depending upon soil
condition. For example as it rains the voids in soil filled with air are replaced by water thus
reducing the quantity of air or when the soil becomes dry the void filled with water are occupied
by air.
Organic matter
The decaying process of living organisms such as plants and animals in soil results in formation
of organic matter.
The organs of dead animals, roots, leaves and wood of plants go through decaying process due to
physical and chemical activities due to this decomposition the organic matter is formed.
BTEC Higher National Diploma in Civil Engineering MT/Bsc Civil/04/33
A.A.M.ASAM Page 4
Mineral particles
The solid components of soils consist of crystalline material called minerals. Mineral particles
are categorized based on their structure and chemical composition. Oxygen and silicon minerals
are most significant to geo- technical engineers. Fine grained soils consist of mineral particles
which are platy in nature.
Task 02
BTEC Higher National Diploma in Civil Engineering MT/Bsc Civil/04/33
A.A.M.ASAM Page 5
a)
=
+
=
+
=
1 +
=
1 +1
=
1 +
b)
= +
+
= = (1 )
= = (1 )
= 1 =
1 =
1 +
,
=
=
(1 )1 + = (1 )
=
=
+ =
1 + (1 )1
= 1 + 1 = 1 + 1
1 + =(1 + )
1 +
BTEC Higher National Diploma in Civil Engineering MT/Bsc Civil/04/33
A.A.M.ASAM Page 6
Task-03
Sample size 75 75 30
Normal stress : 200 /2
Shear Stress at failure : 175 /2
a)
= 1 + 1 1
1 = 0,
= 1
175=200 1
1 =175
200
1 =ta1(175
200)
1 = 410
BTEC Higher National Diploma in Civil Engineering MT/Bsc Civil/04/33
A.A.M.ASAM Page 7
b)
Soil friction angle is a shear strength parameter of soils. Its definition is derived from the Mohr-
Coulomb failure criterion and it is used to describe the friction shear resistance of soils together
with the normal effective stress.
In the stress plane of Shear stress-effective normal stress, the soil friction angle is the angle of
inclination with respect to the horizontal axis of the Mohr-Coulomb shear resistance line.
Description USCS
Soil friction angle []
Reference min max
Specific
value
Well graded gravel, sandy gravel, with little or
no fines GW 33 40 [1],[2],
Poorly graded gravel, sandy gravel, with little
or no fines GP 32 44 [1],
Sandy gravels Loose (GW,
GP) 35 [3 cited in 6]
Sandy gravels Dense (GW,
GP) 50 [3 cited in 6]
Silty gravels, silty sandy gravels GM 30 40 [1],
Clayey gravels, clayey sandy gravels GC 28 35 [1],
Well graded sands, gravelly sands, with little
or no fines SW 33 43 [1],
Well-graded clean sand, gravelly sands Compacted
SW - - 38 [3 cited in 6]
Well-graded sand, angular grains Loose (SW) 33 [3 cited in 6]
Well-graded sand, angular grains Dense (SW) 45 [3 cited in 6]
Poorly graded sands, gravelly sands, with little
or no fines SP 30 39 [1], [2],
Poorly-garded clean sand Compacted SP - - 37 [3 cited in 6]
Uniform sand, round grains Loose (SP) 27 [3 cited in 6]
Uniform sand, round grains Dense (SP) 34 [3 cited in 6]
Sand SW, SP 37 38 [7],
Loose sand (SW, SP) 29 30 [5 cited in 6]
Medium sand (SW, SP) 30 36 [5 cited in 6]
BTEC Higher National Diploma in Civil Engineering MT/Bsc Civil/04/33
A.A.M.ASAM Page 8
Dense sand (SW, SP) 36 41 [5 cited in 6]
Silty sands SM 32 35 [1],
Silty clays, sand-silt mix Compacted SM - - 34 [3 cited in 6]
Silty sand Loose SM 27 33 [3 cited in 6]
Silty sand Dense SM 30 34 [3 cited in 6]
Clayey sands SC 30 40 [1],
Calyey sands, sandy-clay mix compacted SC 31 [3 cited in 6]
Loamy sand, sandy clay Loam SM, SC 31 34 [7],
Inorganic silts, silty or clayey fine sands, with
slight plasticity ML 27 41 [1],
Inorganic silt Loose ML 27 30 [3 cited in 6]
Inorganic silt Dense ML 30 35 [3 cited in 6]
Inorganic clays, silty clays, sandy clays of low
plasticity CL 27 35 [1],
Clays of low plasticity compacted CL 28 [3 cited in 6]
Organic silts and organic silty clays of low
plasticity OL 22 32 [1],
Inorganic silts of high plasticity MH 23 33 [1],
Clayey silts compacted MH 25 [3 cited in 6]
Silts and clayey silts compacted ML 32 [3 cited in 6]
Inorganic clays of high plasticity CH 17 31 [1],
Clays of high plasticity compacted CH 19 [3 cited in 6]
Organic clays of high plasticity OH 17 35 [1],
Loam ML, OL,
MH, OH 28 32 [7],
Silt Loam ML, OL,
MH, OH 25 32 [7],
Clay Loam, Silty Clay Loam
ML, OL,
CL, MH,
OH, CH
18 32 [7],
Silty clay OL, CL,
OH, CH 18 32 [7],
Clay CL, CH, 18 28 [7],
BTEC Higher National Diploma in Civil Engineering MT/Bsc Civil/04/33
A.A.M.ASAM Page 9
OH, OL
Peat and other highly organic soils Pt 0 10 [2],
Correlation between SPT-N value, friction angle, and relative density
SPT N3
[Blows/0.3 m - 1 ft] Soi packing
Relative Density
[%]
Friction angle
[]
< 4 Very loose < 20 < 30
4 -10 Loose 20 - 40 30 35
10 - 30 Compact 40 - 60 35 40
30 - 50 Dense 60 - 80 40 45
> 50 Very Dense > 80 > 45
REFERENCES
1. Swiss Standard SN 670 010b, Characteristic Coefficients of soils, Association of Swiss Road and Traffic Engineers
2. JON W. KOLOSKI, SIGMUND D. SCHWARZ, and DONALD W. TUBBS, Geotechnical Properties of Geologic Materials, Engineering Geology in Washington,
Volume 1, Washington Division of Geology and Earth Resources Bulletin 78, 1989, Link
3. Carter, M. and Bentley, S. (1991). Correlations of soil properties. Penetech Press Publishers, London.
4. Meyerhof, G. (1956). Penetration tests and bearing capacity of cohesionless soils. J Soils Mechanics and Foundation Division ASCE, 82(SM1).
5. Peck, R., Hanson,W., and Thornburn, T. (1974). Foundation Engineering Handbook. Wiley, London.
6. Obrzud R. &Truty, A.THE HARDENING SOIL MODEL - A PRACTICAL GUIDEBOOK Z Soil.PC 100701 report, revised 31.01.2012
7. Minnesota Department of Transportation, Pavement Design, 2007
BTEC Higher National Diploma in Civil Engineering MT/Bsc Civil/04/33
A.A.M.ASAM Page 10
Citation :
Geotechdata.info, Angle of Friction, http://geotechdata.info/parameter/angle-of-friction.html (as
of September 14.12.2013).
c)
= 1
= 150 410
= 130 /2
Task 04
a)
=
= 0.48
0.17 = 2.82
=()
= (0.27)2
0.480.17 = 0.89
BTEC Higher National Diploma in Civil Engineering MT/Bsc Civil/04/33
A.A.M.ASAM Page 11
b)
The Unified Soil Classification System (USCS) is a soil classification system used in
engineering and geology to describe the texture and grain size of a soil. The classification system
can be applied to most unconsolidated materials, and is represented by a two-letter symbol. Each
letter is described below (with the exception of Pt):
First and/or second letters Second letter
Letter Definition
G gravel
S sand
M silt
C clay
O organic
Letter Definition
P poorly graded (uniform particle sizes)
W well-graded (diversified particle sizes)
H high plasticity
L low plasticity
According to particle size distribution curve
Coarse grained soils more than 50% of retained on No 200 sieve
% of gravel
BTEC Higher National Diploma in Civil Engineering MT/Bsc Civil/04/33
A.A.M.ASAM Page 12
Task 05
a) Find the total expected settlement after the fill is placed.
Settlement in a structure refers to the distortion or disruption of parts of a building due to either;
unequal compression of its foundations, shrinkage such as that which occurs in timber framed
buildings as the frame adjusts its moisture content, or by undue loads being applied to the
building after its initial construction Settlement should not be confused with subsidence which
results from the load-bearing ground upon which a building sits reducing in level, for instance in
areas of mine workings where shafts collapse underground.
Some settlement is quite normal after construction has been completed, but unequal settlement
may cause significant problems for buildings. Traditional green oak framed buildings are
designed to settle with time as the oak seasons and warps, lime mortar rather than Portland
cement is used for its elastic properties and glazing will often employ small leaded lights which
can accept movement more readily than larger panes.
= ( + )
= ( 0.5 0.4
1 + 0.5) 4
= 0.27
b) Construction is expected to start after the consolidation is 90% complete. If the
coefficient of consolidation (cv) is 2.8 106 /, calculate the duration between placement of fill and commencement of construction work
=
0.848 = 2.8106
4
t = 1211428.57 min / 841days
BTEC Higher National Diploma in Civil Engineering MT/Bsc Civil/04/33
A.A.M.ASAM Page 13
c) What techniques would you recommend to speed up the consolidation process so
that construction work could start sooner?
Primary consolidation
This method assumes consolidation occurs in only one-dimension. Laboratory data is used to
construct a plot of strain or void ratio versus effective stress where the effective stress axis is on
a logarithmic scale. The plot's slope is the compression index or recompression index. The
equation for consolidation settlement of a normally consolidated soil can then be determined to
be:
where
c is the settlement due to consolidation.
Cc is the compression index.
e0 is the initial void ratio.
H is the height of the soil.
zf is the final vertical stress.
z0 is the initial vertical stress.
Cc can be replaced by Cr (the recompression index) for use in overconsolidated soils where the
final effective stress is less than the preconsolidation stress. When the final effective stress is
greater than the preconsolidation stress, the two equations must be used in combination to model
both the recompression portion and the virgin compression portion of the consolidation process,
as follows:
wherezc is the reconsolidation stress of the soil.
Secondary compression
Secondary compression is the compression of soil that takes place after primary consolidation.
Even after the reduction of hydrostatic pressure some compression of soil takes place at slow
rate. This is known as secondary compression. Secondary compression is caused by creep,
viscous behavior of the clay-water system, compression of organic matter, and other processes.
BTEC Higher National Diploma in Civil Engineering MT/Bsc Civil/04/33
A.A.M.ASAM Page 14
In sand, settlement caused by secondary compression is negligible, but in peat, it is very
significant. Due to secondary compression some of the highly viscous water between the points
of contact is forced out.
Secondary compression is given by the formula
Where H0 is the height of the consolidating medium
e0 is the initial void ratio
Ca is the secondary compression index
t is the length of time after consolidation considered
t90 is the length of time for achieving 90% consolidation
BTEC Higher National Diploma in Civil Engineering MT/Bsc Civil/04/33
A.A.M.ASAM Page 15
Task 07
a)
= 25 = 20 = 18/3
= 18 1.5 = 27/3
= + + 0.5
= 20 20.72 + 27 10.66 +1
2 18 6.765 1.5
= 793.567
Let FOS
=5
=793.597
3= 264.516
=
500
3
1.5 1.53
= 222.22/3
>
b)
= 750/3
1.5 1.5
= 333.33 /3
BTEC Higher National Diploma in Civil Engineering MT/Bsc Civil/04/33
A.A.M.ASAM Page 16
=1 + +
1
2
= 3
=1
3 20 20.72 + 27 10.66 +
1
2 18 6.765
=750/
1.5
750
1.5 =
1
3 20 20.72 + 27 10.66 +
1
2 18 6.765
1500 = (702.22 + 60.885)
0 = 60.8852 + 702.22 1500
= 1.841
c)
In developing the bearing capacity equations given in the preceding section we assumed that the
groundwater table is located at a depth much greater than the width, B of the footing. Three
different conditions can arise regarding the location of the groundwater table with respect to the
bottom of the foundation.
BTEC Higher National Diploma in Civil Engineering MT/Bsc Civil/04/33
A.A.M.ASAM Page 17
If the groundwater table is located at a distance D above the bottom of the foundation, the
magnitude of q in the second term of bearing capacity equation should be calculated as
= +
For shallow foundations, the negative effects of high water table on the added pressure to the soil
can be compensated by ensuring that the foundation is wide enough to distribute the resultant
force evenly on the ground. The influence of water table on the bearing capacity of a structure is
reduced. The worst scenario arises when the soil supporting a structure becomes completely
saturated.
When the level of water table is considered to be directly at the base of a foundation in
comparison to the slip lines, the water table influences the stability lines by extending them
deeper in lateral direction.
BTEC Higher National Diploma in Civil Engineering MT/Bsc Civil/04/33
A.A.M.ASAM Page 18
Task - 08
= 24 /3
= 17.5 /3
= 5 /2
= 28
= tan2 45
2
= tan2 45 28
2
= 0.361
= 1/ = 2.77
= 1 , = 5
a)
Active pressure
0.361 17.5 5
= 31.59 /2
Active force
= 0.5
0.5 31.59 5
= 78.97
Passive pressure
2.77 17.5 1
= 48.47 /2
BTEC Higher National Diploma in Civil Engineering MT/Bsc Civil/04/33
A.A.M.ASAM Page 19
Passive force
= 0.5( )
= 0.5 48.47 1
= 24.23
Pressure due to surcharge
0.361 5
= 1.81 /2
Surcharge force
=
= 1.81 5
= 9.05
b)
1 = 1 = 24 2 1 1 = 48
2 = 1 = 24 7 1 1 = 168
3 = 1 = 24 0.5 6 1 1 = 72
Overturning
| = / :
= (1 1) + (2 1.5) + (3 0.5) + ( 0.333)
( 2.5) + ( 1.666)
= 344.07/154.2
= 2.23 > = 1.5
BTEC Higher National Diploma in Civil Engineering MT/Bsc Civil/04/33
A.A.M.ASAM Page 20
c) Modern retaining wall types such as gabion walls and mechanically stabilized earth (MSE) walls are gaining popularity of conventional retaining walls types. Try to
explain the reasons for this trend by identifying the advantages they have over
conventional systems.
Traditionally, retaining walls were known as mass retainers or gravity walls and were made of stone
or rubble heavy enough to hold back the weight of the earth heaped against them. Often these
structures would be built at an angle, or batter, leaning back into the retained soil. This kind of
structure, however, is expensive because of the amount of material and labour involved in its
construction, and is now rarely used.
Due to advantages in economics, constructability, and
aesthetics, the construction of mechanically stabilized
earth (MSE) walls is now commonplace. An MSE wall
consists of soil, reinforcement, and facing to retain earth
and support overlying structures. Thirty- to forty-foot
high walls are not uncommon. Reinforcement often
consists of geogrids or steel reinforcement strips, while
the facing commonly consists of segmental precast
concrete units, gabion baskets, metallic panels, or
geosynthetic facing. There are many different MSE wall
construction materials, making it more important for
Contractors and design Engineers to understand how the
products work with the remainder of the system.
Advantages of gabion walls
1. Strong base that provides strength from being drag away by river or stream. 2. Reduce velocity of water as the energy dissipated by the rocks, thus reduce erosion. 3. Its flexibility gives allowance to small ground movement. 4. In most cases, as time goes, voids will be filled by vegetation and silt which will
reinforce the structure and give extra strength.
5. Depends on the availability of material and equipment, handling and transporting material is easy and this reduce the time of construction.
6. Voids can be easily seen between the rocks which makes high permeability to the gabion wall. It allows water to flow through the structure which can maintain the water level in
the ground (Groundwater level) to be low.
BTEC Higher National Diploma in Civil Engineering MT/Bsc Civil/04/33
A.A.M.ASAM Page 21
Task 9 Moment Distribution (P9, M3)
Determine the reactions at the supports (RA, RB, RC, MA) using the moment distribution method. Assume A is fixed and B & C are roller supports. EI is constant.
All calculations should be provided.
Fix end moment
FEMAB=W L2
12 =
1252
12= -25kN/M
FEMBA=+wL2
12=
1252
12= 25kN/m
FEMBC=PL
8=102.5
8=3.125kN/m
FEMCB=+PL
8=
102.5
8= 3.125kN/m
Stiffness factor
KAB=KBA =4EI
L=
4EI
5= 0.8EI
KBC = KCB=4EI
L=
4EI
2.5= 1.6EI
BTEC Higher National Diploma in Civil Engineering MT/Bsc Civil/04/33
A.A.M.ASAM Page 22
Distribution factor
DFAB=KBA
KAB +K wall=
0.8EI
0.8EI+(wall stiffness ) =0.0
DFBA=KBA
KBA +KBC=
0.8EI
0.8EI+1.6EI =0.33
DFBC=KBC
KBA +KBC =
1.6EI
0.8EI+1.6EI =0.67
DFCB=KCB
KCB= 1.00
Joints A B C
members AB BA BC CB
Distribution factor 0 0.33 0.67 1
Carry over factor 0.5 0.5 0.5 0.5
Computed end
moment
-25 25 -3.125 3.125
Distribution 7.218 14.656
Carry over moment 3.609 7.328