For 1st year civil engineering students.

1. Introduction to
Geotechnical
Engineering

2. At least 17 families lost their homes in a landslide in Barangay Poblacion in
Bakun town, Benguet due to bad weather caused by Typhoon Maring.

3. Slope failure in the Payatas landfill in Quezon City, Philippines. This
failure, which killed at least 330 persons, occurred July 10th 2000 after
two weeks of heavy rain from two typhoons.

4. 1999 Cherry Hills landslide
On August 3, 1999, heavy rain induced by Typhoon Ising (Olga) spelled
disaster for residents of Cherry Hills Subdivision in Antipolo City, when the
ground beneath them broke apart and slid down the mountain.

5. 2018 Itogon, Benguet landslides
Most of the fatalities were recorded in landslides that occurred at a mining town
in Itogon, Benguet on September 15, 2018. At least 58 people have been
reported dead, 31 of whom lived in Barangay Ucab where the biggest landslide
happened.

6. Toppled apartment buildings Niigata, Japan 1964 Earthquake

7. The Leaning Tower of Pisa
-leaning since 13th century

8. ❖ Landslide in Bakun town, Benguet
❖ Payatas landfill in Quezon City
❖ Cherry Hills landslide
❖ Itogon, Benguet landslides
❖ Toppled apartment buildings Niigata, Japan
❖ The Leaning Tower of Pisa
Soil Failures:
▪ Slope Stability
▪ Soil Liquefaction
▪ Soil Settlement

9. SOIL STABILITY is a measure of the ability of soil aggregates—soil particles that
bind together—to resist breaking apart when exposed to external forces such as
water erosion and wind erosion, shrinking and swelling processes, and tillage.

10. SOIL LIQUEFACTION occurs when a cohesionless saturated or partially
saturated soil substantially loses strength and stiffness in response to an applied
stress such as shaking during an earthquake or other sudden change in stress
condition, in which material that is ordinarily a solid behaves like a liquid.

11. SOIL SETTLEMENT is defined as the downward vertical movement of the
ground due to changes in stresses within it. Excessive ground movements can
cause damage in buildings, structures and transport infrastructure, from
bridges and tunnels to road pavements and railways.

12. What is a
Geotechnical
Engineer?
What do they
do?
What do they
design?
Geotechnical Engineering
Overview

13. What is a
Geotechnical
Engineer?
What do they
do?
What do they
design?
Geotechnical Engineering
Overview

14. GEOTECHNICAL ENGINEERING is the branch of civil engineering concerned
with the engineering behavior of earth materials. It uses the principles of soil
mechanics and rock mechanics for the solution of its respective engineering
problems.

15. What is a
Structural
Engineer?
What do they
do?
What do they
design?
Structural Engineering
Overview

16. GEOTECHNICAL ENGINEERS are involved in all stages of the design of
structures, from concept to construction. Their work is essential in the
design and planning process as they assess the integrity of soil, clay, silt,
sand, and rock, prior to construction commencing.
The role of a geotechnical engineer is so important because they are
responsible for evaluating the ground conditions of a site prior to build-out.
Ground conditions can vary greatly even on a small site, and with added
challenges such as climate change impacting the environment with
droughts and floods, the role of a geotechnical engineer is becoming even
more significant. They must determine whether the ground can withstand
the added pressures or changes brought by construction, which can
ultimately avoid costly issues further into the project.

17. The important test conducted on soil before building and road construction are:
1. Moisture content test
2. Atterberg limits tests
3. Specific gravity of soil
4. Dry density of soil
5. Compaction test (Proctor’s test)
OVEN DRYING method is most common
and accurate method to determine the
moisture content of soil. In this method the
soil sample is taken and weighed and put it
in oven and dried at 110o + 5oC. After 24
hours soil is taken out and weighed. The
difference between the two weights is
noted as weight of water or moisture
content in the soil.
OVEN DRYING

18. Atterberg Limits Test on Soil
To measure the critical water content of a fine grained soil, Atterberg provided
3 limits which exhibits the properties of fine grained soil at different conditions.
The limits are liquid limit, plastic limit and shrinkage limit. These limits are
calculated by individual tests as follows.
Liquid Limit Test on Soil
In this test, Casagrande’s liquid limit device is used which consist a cup with
moving up and down mechanism. The cup is filled with soil sample and groove
is created in the middle of cup with proper tool. When the cup is moved up and
down with the help of handle the groove becomes closed at some point.
CASAGRANDE’S

19. Plastic Limit Test on Soil
Take the soil sample and add some
water to make it plastic enough to shape
into small ball. Leave it for some time
and after that put that ball in the glass
plate and rolled it into threads of 3mm
diameter.
Shrinkage Limit Test on Soil
In case of shrinkage limit, the
water content in the soil is just
sufficient to fill the voids of soil.
That is degree of saturation is of
100%. So, there is no change in
volume of soil if we reduce the
shrinkage limit. It is determined by
the below formula for the given
soil sample

20. PYCNOMETER is weighed in 4 different cases that is empty weight (M1),
empty + dry soil (M2), empty + water + dry soil (M3) and Pycnometer
filled with water (M4) at room temperature. From these 4 masses specific
gravity is determined by below formula.

21. Proctor’s Compaction Test on Soil
Proctor’s test is conducted to determine compaction characteristics of
soil. Compaction of soil is nothing but reducing air voids in the soil by
densification. The degree of Compaction is measured in terms of dry
density of soil
The Sand cone apparatus is used to
determine the volume of the test hole.
Fill the apparatus with calibrated sand
and weigh it. The scale and balance
must be leveled and properly adjusted
before any weighing are made. The
volumeter may also be used for this
determination, in which case weighing
is not necessary.

22. CLASSIFICATION OF SOIL
In general, there are two major categories into which the classification
system developed in the past can be grouped.
1. Textural classification system by US Department of Agriculture
(USDA). The textural classification is based on the particle-size
distribution of the percent of sand, silt, and clay-size fractions present in
a given soil.
2. The other major category is based on the engineering behavior of soil
and takes into consideration the particle-size distribution and the
plasticity (ie., liquid limit and plasticity index).
-AASHTO classification system
- Unified Classification System (USCS)

24. Grain Size Distribution:
Course Fraction: Retained on No. 200 sieve
Gravel: Retained on No. 4 sieve
Sand: Passed No.4 sieve but retained No. 200 sieve
Fine Fraction: Passed on No. 200 sieve
Unified Classification System (USCS)
Sieving Analysis
A sieve analysis (or gradation test) is a practice or
procedure used in civil engineering and chemical
engineering to assess the particle size
distribution (also called gradation) of a granular
material by allowing the material to pass through a
series of sieves of progressively smaller mesh size
and weighing the amount of material that is
stopped by each sieve as a fraction of the whole
mass

26. US Department of Agriculture (USDA Method
This classification method is based on the particle-size limits as described
under the USDA system:
Gravel: Greater than 2 mm grain size
Sand: 2 mm to 0.05 mm grain size
Silt: 0.05 mm to 0.002 mm grain size
Clay: Less than 0.002 mm grain size

27. American Association of Highway and Transportation Officials Method According
to this system, soil is classified into seven major groups: A-1 through A-7.
-Soils classified under groups A-1, A-2, and A-3 are granular materials of which
35% or less of the particles pass through the No. 200 sieve
-Soils of which more than 35% pass through the No. 200 sieve are classified
under groups A-4, A-5, A-6, and A-7
To classify a soil according to AASHTO, one must apply the test data from left
to right. By process of elimination, the first group from the left into which the
test data fit is the correct classification.

29. What is a
Structural
Engineer?
What do they
do?
What do they
design?
Structural Engineering
Overview

30. Geotechnical engineering is the study of the behavior of soils under the
influence of loading forces and soil-water interactions. This knowledge is
applied to the design of foundations, retaining walls, earth dams, clay liners,
and geosynthetics for waste containment.
Following are different types of foundations used in construction:
1.Shallow foundation
1. Individual footing or isolated footing
2. Combined footing
3. Strip foundation
4. Raft or mat foundation
2.Deep Foundation
1. Pile foundation
2. Drilled Shafts or caissons

31. 1. Individual Footing or Isolated Footing
Individual footing or an isolated footing is
the most common type of foundation
used for building construction. This
foundation is constructed for a single
column and also called a pad foundation.
The shape of individual footing is square
or rectangle and is used when loads from
the structure is carried by the columns.
Size is calculated based on the load on
the column and the safe bearing capacity
of soil. Rectangular isolated footing is
selected when the foundation
experiences moments due to the
eccentricity of loads or due to horizontal
forces.

32. 2. Combined Footing
Combined footing is constructed when two or more columns are close enough
and their isolated footings overlap each other. It is a combination of isolated
footings, but their structural design differs. The shape of this footing is a
rectangle and is used when loads from the structure is carried by the columns

33. 3. Spread footings or Strip footings and Wall footings
Spread footings are those whose base is wider than a typical load-bearing
wall foundations. The wider base of this footing type spreads the weight
from the building structure over more area and provides better stability.

34. 4. Raft or Mat Foundations
Raft or mat foundations are the types of foundation which are spread across the
entire area of the building to support heavy structural loads from columns and
walls. The use of mat foundation is for columns and walls foundations where the
loads from the structure on columns and walls are very high. This is used to
prevent differential settlement of individual footings, thus designed as a single
mat (or combined footing) of all the load-bearing elements of the structure.

35. TYPES OF DEEP FOUNDATION
5. Pile Foundations
Pile foundation is a type of deep
foundation which is used to transfer
heavy loads from the structure to a
hard rock strata much deep below the
ground level. Pile foundations are used
to transfer heavy loads of structures
through columns to hard soil strata
which is much below ground level
where shallow foundations such as
spread footings and mat footings
cannot be used. This is also used to
prevent uplift of the structure due to
lateral loads such as earthquake and
wind forces.

36. 6. Drilled Shafts or Caisson
Foundation
Drilled shafts, also called as caissons,
is a type of deep foundation and has
an action similar to pile foundations
discussed above, but are high
capacity cast-in-situ foundations. It
resists loads from structure through
shaft resistance, toe resistance
and/or combination of both of these.
The construction of drilled shafts or
caissons are done using an auger.

37. Retaining walls are relatively rigid walls used for supporting soil laterally so that it
can be retained at different levels on the two sides. Retaining walls are structures
designed to restrain soil to a slope that it would not naturally keep to.

38. Earth dam is a large artificial dam. It is typically created by the placement
and compaction of a complex semi-plastic mound of various compositions
of soil or rock. It has a semi-pervious waterproof natural covering for its
surface and a dense, impervious core.

39. A clay liner serves as a hydraulic barrier to flow of fluids. Clay liners are used
to minimize infiltration of water into buried waste (cover systems) or to
control release of leachate from the waste (liner systems). To meet these
objectives, clay liners must have low hydraulic con- ductivity over long
periods of time.
Geosynthetic clay liners (GCLs)
represent a relatively new
technology (developed in 1986)
currently gaining acceptance
as a barrier system in municipal
solid waste landfill applications.
Federal and some state
regulations specify design
standards for bottom liners and
final covers.