De La Salle University

DASMARIÑAS
CITY OF DASMARIÑAS, CAVITE, PHILIPPINES

COLLEGE OF ENGINEERING, ARCHITECTURE AND TECHNOLOGY

Civil and Sanitary Engineering Department

Engr. Jeric Sarte

Engr. Jeffrey Tepace

 MODULE 1: COURSE INTRODUCTION

Introductory Remarks

Good day Fellow Lasallian! 

Welcome to our Geotechnical Engineering 1 course! We hope you’re ready for a rewarding learning
experience with plenty of comprehensive lessons, engaging discussions, and gainful assessments.

This course deals with the study of the identification and classification of soils and rocks, site
investigation and subsurface exploration, the physical and index properties of soil, compaction, water
flow through soils, subsurface stress and deformation phenomena in soils, and the relevance of these
topics as they affect soil strength, compressibility, stability, and drainage. A thorough knowledge of
engineering geology and mechanics of deformable bodies is imperative. 

Your path ahead may not be easy but with enough determination and active participation we hope that
you'll finish this course with substantial learning. Rest assured that we will do our best to be very attentive
to your concerns and that despite this unique situation we are in right now, we will be able to accomplish
all the challenges ahead. Here's hoping for a fruitful journey for us this semester. 

Good luck and God Bless.

Animo La Salle! 

Gospel Reading
3 
Then he told them many things in parables, saying: “A farmer went out to sow his seed. 4 As he was
scattering the seed, some fell along the path, and the birds came and ate it up. 5 Some fell on rocky places,
where it did not have much soil. It sprang up quickly, because the soil was shallow. 6 But when the sun
came up, the plants were scorched, and they withered because they had no root. 7 Other seed fell among
thorns, which grew up and choked the plants. 8 Still other seed fell on good soil, where it produced a crop
—a hundred, sixty or thirty times what was sown.
Matthew 13:3-8

Although this is often known as the parable of the sower and the seed, it can also be said this is a parable
about the soil. All four types of soil are essentially the same dirt but are in different conditions and
respond in different ways to cultivation. How I apply this passage is by asking questions: Can I be
“cultivated” in my life? How correctable am I? How quickly do I repent? Can I self-correct? The greater
my yielding to God’s cultivation the greater the capacity of my fruitfulness in life.

Learning Objectives

In this module we aim to understand the development of Soil Mechanics throughout history: from its first
application in the construction of pyramids of Egypt to the more recent developments spearheaded by the
likes of Karl Terzaghi. With this understanding we may not just have a deeper grasp on the fundamentals
of Geotechnical Engineering but also on its significance to actual applications to Civil Engineering
structures. 
Introduction to Soil Mechanics

For engineering purposes, soil is defined as the uncemented aggregate of mineral grains and decayed
organic matter (solid particles) with liquid and gas in the empty spaces between the solid particles. Soil is
used as a construction material in various civil engineering projects, and it supports structural
foundations. Thus, civil engineers must study the properties of soil, such as its origin, grain-size
distribution, ability to drain water, compressibility, strength, and its ability to support structures and resist
deformation.

Soil mechanics is the branch of science that deals with the study of the physical properties of soil and the
behavior of soil masses subjected to various types of forces. Soils engineering is the application of the
principles of soil mechanics to practical problems. Geotechnical engineering is the subdiscipline of civil
engineering that involves natural materials found close to the surface of the earth. It includes the
application of the principles of soil mechanics and rock mechanics to the design of foundations, retaining
structures, and earth structures.

The record of a person’s first use of soil as a construction material is lost in antiquity. In true engineering
terms, the understanding of geotechnical engineering as it is known today began early in the 18th century.
For years, the art of geotechnical engineering was based on only past experiences through a succession of
experimentation without any real scientific character. Based on those experimentations, many structures
were built—some of which have crumbled, while others are still standing.

Refer to the printed powerpoint lecture on Introduction to Soil Mechanics (Lesson 1. Soil Mechanics)
for a more detailed discussion on this topic.

Discussion Assessment:

Search for actual construction site incidents/videos/cases/designs involving soil or soil behavior.
Anything that shows the need for knowledge of soil mechanics. (e.g. construction workers buried in
collapse of excavated soil).

 If from an online source, you may attach link to the video or article. If from anywhere near you or
within your community, you may attach actual photo. Anything that can prove authenticity of
your sample case.
 Give your personal insight as to how this particular case proves the importance of knowledge of
soil mechanics in civil engineering constructions. 
 MODULE 2: ENGINEERING SOIL PROPERTIES

Gospel Reading
33 
But seek ye first the kingdom of God, and his righteousness; and all these things shall be added unto
you.
Matthew 6:3

The Almighty calls us to seek first the kingdom of God instead of worrying about what we’ll eat, how
we’ll dress — temporal or superficial concerns. Our Father, who is love and far more trustworthy than
man, encourages us through Matthew 6:33 and other Bible verses to keep an eternal perspective even as
we cross each day off of our calendars. You and I are called to refuse worry and anxiety. Instead, we seek
first the kingdom of God.

Learning Objectives

In this module, we aim to accomplish the following:

 Understand how soil is formed by weathering of rock; the different properties of soil such as
particle size distribution, void ratio, porosity, degree of saturation, moisture content,  and unit
weight.
 Understand the four basic states of soil depending on its moisture content. The soil moisture
content of soil is the quantity of water it contains. Water content is used in a
wide range of scientific and technical areas and is expressed as a ratio, which can
range from 0 (completely dry) to the value of the materials’ porosity at
saturation.
 Define the different standards in classification of soils. Classification systems provide a
common language to concisely express the general characteristics of soils, which are
infinitely varied, without detailed descriptions.

Topic Discussion

Origin of Soil

In general, soils are formed by weathering of rocks. The physical properties of soil are dictated primarily
by the minerals that constitute the soil particles and, hence, the rock from which it is derived. In this
lesson we will discuss the following:
 The formation of various types of rocks and the rock cycle.
 Formation of soil by mechanical and chemical weathering of rock.
 The basic types of rocks based on their origin
 Classification of rocks

Refer to the printed lecture powerpoint on Soil Formation (Lesson 2. Soil Formation) for a more
comprehensive discussion on this topic.
Particle Size Distribution

Based on the size of the particles, soil can be classified as gravel, sand, silt, and clay. In this lesson, two
laboratory procedures in determining particle size distribution of soil will be discussed. Moreover, some
significant properties of soil, soil classification standards, and soil particle shapes will also be introduced. 

Refer to the printed lecture powerpoint on Particle Size Distribution (Lesson 3. Soil Grain Size) for a
more comprehensive discussion on this topic.

Weight-Volume Relationships

A given volume of soil in natural occurrence consists of solid particles and the void spaces between the
particles. The void space may be filled with air and/or water; hence, soil is a three-phase system. If there
is no water in the void space, it is a dry soil. If the entire void space is filled with water, it is referred to as
a saturated soil. However, if the void is partially filled with water, it is a moist soil. Hence it is important
in all geotechnical engineering works to establish relationships between weight and volume in a given soil
mass. In this chapter we will discuss the following:
 Define and develop nondimensional volume relationships such as void ratio, porosity, and degree
of saturation.
 Define and develop weight relationships such as moisture content and unit weight (dry, saturated,
and moist) in combination with the volume relationships.

 Refer to the printed lecture powerpoint on Weight Volume Relationships (Lesson 4) for a more
comprehensive discussion on this topic.

Atterberg Limits

When clay minerals are present in fine-grained soil, the soil can be remolded in the presence of some
moisture without crumbling. This cohesive nature is caused by the adsorbed water surrounding the clay
particles. In the early 1900s, a Swedish scientist named Atterberg developed a method to describe the
consistency of fine-grained soils with varying moisture contents. At a very low moisture content, soil
behaves more like a solid. When the moisture content is very high, the soil and water may flow like a
liquid. Hence, on an arbitrary basis, depending on the moisture content, the behavior of soil can be
divided into four basic states—solid, semisolid, plastic, and liquid—as shown in the figure below.
The moisture content, in percent, at which the transition from solid to semisolid state takes place is
defined as the shrinkage limit. The moisture content at the point of transition from semisolid to plastic
state is the plastic limit, and from plastic to liquid state is the liquid limit. These parameters are also
known as Atterberg limits. This lesson describes the procedures to determine the Atterberg limits. Also
discussed in this lesson are soil structure and geotechnical parameters, such as activity and liquidity
index, which are related to Atterberg limits.

Refer to the printed lecture powerpoint on Plasticity of Soil (Lesson 5) for a more comprehensive
discussion on this topic.

Soil Classification

Different soils with similar properties may be classified into groups and subgroups according to their
engineering behavior. Classification systems provide a common language to concisely express the general
characteristics of soils, which are infinitely varied, without detailed descriptions. Most of the soil
classification systems that have been developed for engineering purposes are based on simple index
properties such as particle-size distribution and plasticity. Although several classification systems are now
in use, none is totally definitive of any soil for all possible applications because of the wide diversity of
soil properties.

In general, there are two major categories into which the classification systems developed in the past can
be grouped.
1. 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. In this lesson, we will discuss the textural classification
system developed by the U.S. Department of Agriculture.
2. The other major category is based on the engineering behavior of soil and takes into consideration
the particle-size distribution and the plasticity (i.e., liquid limit and plasticity index). Under this
category, there are two major classification systems in extensive use now:
       a. The AASHTO classification system, and
       b. The Unified classification system.

The guidelines for classifying soil according to both aforementioned systems will be discussed in detail in
the printed lecture powerpoint on Lesson 6. Soil Classification.
Midterm Enabling Assessment 1

 Based on your class number, answer the corresponding set of problem questions for Midterm
Enabling Assessment 1.
o Set A: Class Nos. 1, 5, 9, 13, 17, 21, 25, 29
o Set B: Class Nos. 2, 6, 10, 14, 18, 22, 26, 30
o Set C: Class Nos. 3, 7, 11, 15, 19, 23, 27, 31
o Set D: Class Nos. 4, 8, 12, 16, 20, 24, 28, 32

 Write your number, ID number, section, class number, and signature at the top of each page of
your answer.
 Present your solution in an orderly manner. Box your final answer.

Midterm Summative Assessment 1

 Based on your class number, answer the corresponding set of problem questions for Midterm
Enabling Assessment 1.
o Set A: Class Nos. 1, 7, 11, 16, 19, 21, 23, 27
o Set B: Class Nos. 3, 5, 9, 12, 15, 26, 28, 32
o Set C: Class Nos. 2, 6, 13, 17, 20, 25, 29, 31
o Set D: Class Nos. 4, 8, 10, 14, 18, 22, 24, 30

 Write your number, ID number, section, class number, and signature at the top of each page of
your answer.
 Present your solution in an orderly manner. Box your final answer.
 MODULE 3: SOIL COMPACTION AND PERMEABILITY

24 
“Anyone who listens to my teaching and follows it is wise, like a person who builds a house on solid
rock. 25 Though the rain comes in torrents and the floodwaters rise and the winds beat against that house,
it won’t collapse because it is built on bedrock. 26 But anyone who hears my teaching and doesn’t obey it
is foolish, like a person who builds a house on sand. 27 When the rains and floods come and the winds beat
against that house, it will collapse with a mighty crash.”

Matthew 7:24-27

Learning Objectives

In this module, we aim to accomplish the following:

 Understand the principles of soil compaction in the laboratory and in the field: its significance,
laboratory test methods, factors affecting compaction, and empirical relationships related to
compaction. We aim to be able to solve problems involving different void ratios in soil.
 Understand how water flows through voids in soil. We aim to perform and solve problems
regarding hydraulic conductivity of soils

Topic Discussion

Soil Compaction

In the construction of highway embankments, earth dams, and many other engineering structures, loose
soils must be compacted to increase their unit weights. Compaction increases the strength characteristics
of soils, which increase the bearing capacity of foundations constructed over them. Compaction also
decreases the amount of undesirable settlement of structures and increases the stability of slopes of
embankments. Smooth-wheel rollers, sheepsfoot rollers, rubber-tired rollers, and vibratory rollers are
generally used in the field for soil compaction. Vibratory rollers are used mostly for the densification of
granular soils. Vibrofoot devices are also used for compacting granular soil deposits to a considerable
depth. Compaction of soil in this manner is known as vibroflotation. This lesson discusses in some detail
the principles of soil compaction in the laboratory and in the field.

This lesson includes elaboration of the following:

 Laboratory compaction test methods
  Factors affecting compaction in genera
 Empirical relationships related to compaction
 Structure and properties of compacted cohesive soils
 Field compaction
 Tests for quality control of field compaction
 Special compaction techniques in the field

Check the powerpoint on Soil Compaction (Lesson 7) for the full discussion.

Soil Permeability

Soils are permeable due to the existence of interconnected voids through which water can flow from
points of high energy to points of low energy. The study of the flow of water through permeable soil
media is important in soil mechanics. It is necessary for estimating the quantity of underground seepage
under various hydraulic conditions, for investigating problems involving the pumping of water for
underground construction, and for making stability analyses of earth dams and earth-retaining structures
that are subject to seepage forces.
One of the major physical parameters of a soil that controls the rate of seepage through it is hydraulic
conductivity, otherwise known as the coefficient of permeability. In this lesson, we will study the
following:
 Definition of hydraulic conductivity and its magnitude in various soils
 Laboratory determination of hydraulic conductivity
 Empirical relationship to estimate hydraulic conductivity
 Equivalent hydraulic conductivity in stratified soil based on the direction of the flow of water
 Hydraulic conductivity determination from field tests

You may check in detail the discussion on this topic in the powerpoint attached (Lesson 8. Soil
Permeability).

Seepage

In the preceding chapter, we considered some simple cases for which direct application of Darcy’s law
was required to calculate the flow of water through soil. In many instances, the ow of water through soil
is not in one direction only, nor is it uniform over the entire area perpendicular to the ow. In such cases,
the groundwater ow is generally calculated by the use of graphs referred to as flow nets. The concept of
the flow net is based on Laplace’s equation of continuity, which governs the steady flow condition for a
given point in the soil mass.

In this chapter, we will discuss the following:

 Derivation of Laplace’s equation of continuity and some simple applications of the equation
 Procedure to construct ow nets and calculation of seepage in isotropic and anisotropic soils
 Seepage through earth dams
You may check in detail the discussion on this topic in the powerpoint attached (Lesson 9. Seepage).

Midterm Enabling Assessment 2

 Based on your class number, answer the corresponding set of problem questions for Midterm
Enabling Assessment 1.
o Set A: Class Nos. 2, 6, 10, 14, 18, 22, 26, 30
o Set B: Class Nos. 1, 5, 9, 13, 17, 21, 25, 29
o Set C: Class Nos. 4, 8, 12, 16, 20, 24, 28, 32
o Set D: Class Nos. 3, 7, 11, 15, 19, 23, 27, 31

 Write your number, ID number, section, class number, and signature at the top of each page of
your answer.
 Present your solution in an orderly manner. Box your final answer.

Midterm Summative Assessment 2

 Based on your class number, answer the corresponding set of problem questions for Midterm
Enabling Assessment 1.
o Set A: Class Nos. 4, 8, 10, 14, 18, 22, 24, 30
o Set B: Class Nos. 2, 6, 13, 17, 20, 25, 29, 31
o Set C: Class Nos. 3, 5, 9, 12, 15, 26, 28, 32
o Set D: Class Nos. 1, 7, 11, 16, 19, 21, 23, 27

 Write your number, ID number, section, class number, and signature at the top of each page of
your answer.
 Present your solution in an orderly manner. Box your final answer.