SIWES (IT) REPORT ON SUBSOIL INVESTIGATION (GEOTECHNICAL ASSESSMENT)

UNIVERSITY OF NIGERIA, NSUKKA

FACULTY OF PHYSICAL SCIENCES

DEPARTMENT OF GEOLOGY

REPORT ON STUDENT INDUSTRIAL WORK EXPERIENCE

SCHEME (SIWES) TRAINING PROGRAMME

AT

KDF KONSULT LIMITED

SUBMITTED IN PARIAL FUFILMENT OF THE REQUIREMENT FOR THE STUDENT INDUSTRIAL WORK EXPERIENCE SCHEME

BY

NAME: BASSEY, DANIEL KUFRE

MATRIC NO: 2010/170012

PROGRAMME: GEOLOGY

FROM: MAY - OCTOBER 2014

SUPERVISOR:

TITLE PAGE

A SIWESS REPORT ON GEOTECHNICAL ASSESSMENT

DEDICATION

I dedicate this report first and foremost to Almighty God who has been there right from the

beginning to this very point. Special dedication also to my ever supportive parents, friends, and

colleagues for their relentless support and compassion towards me during the course of my six

months SIWES training.

To God be all the glory.

ACKNOWLEDGMENT

With a deep sense of appreciation, respect and gratitude, I want to say a big thank you to my

parents, brother, sisters, and other relatives and non-relative for their caring attitude and support

from the beginning of my pursuit for B.Sc. degree in Geology to this point. I also want to express

my appreciation to the MD, KDF KONSULT LIMITED, Mr. OLAOYE KAYODE, my immediate

supervisors, Mr. ADENIRAN EMMANUEL TOPE and Mr. OYENIYI ADESHOLA, and other

staff of KDF KONSULT LIMITED for their intellectual support during our work together. Not

forgetting my other IT colleagues. My sincere appreciation also goes to everyone that has been by

me all this while. A Big thanks to you all.

Bassey Daniel Kufre

TABLE OF CONTENTS

Title page …………………………………………………………………………………i

Dedication ………………………………………………………………………………...ii

Acknowledgement ………………………………………………………………………..iii

Table of content …………………………………………………………………………..iv

List of figures ……………………………………………………………………………..

List of plates ……………………………………………………………………………….

CHAPTER ONE: INTRODUCTION

1.1 Brief history of SIWES ……………………………………………………………….1

CHAPTER TWO:

2.1 Company profile ……………………………………………………………………..5

2.2 Brief history of the company ………………………………………………………...6

2.3 Department of the company …………………………………………………………6

2.4 Organogram of company ……………………………………………………………7

CHAPTER THREE

3.1 Activity 1 …………………………………………………………………………....8

3.1.1 Process and Result …………………………………………………………………9

3.1.2 Skill acquired ……………………………………………………………………...17

3.2 Activity 2 ……………………………………………………………………………17

3.2.1 Process and Result …………………………………………………………………18

3.2.2 Skill acquired ………………………………………………………………………31

CHAPTER FOUR

4.1 Summary …………………………………………………………………………..34

4.2 Main activities of the company ……..……………………………………………...34

4.3 Benefits and Challenges …………………………………………………………....35

4.4 Recommendation …………………………………………………………………...35

4.5 Lesson/skills acquired ….…………………………………………………………...36

CHAPTER FIVE: CONCLUSION …………………………………….………….....37

LIST OF FIGURES

FIGURE NUMBER PAGE

FIGURE 1: Organizational chart of KDF KONSULT LTD…………………………………...7

FIGURE 2: Dutch Cone Penetrometer (2.5 Ton Capacity)……………………………………10

FIGURE 3: Schematic of a Geotechnical Borehole……………………………………………17

FIGURE 4: Geotechnical Borehole Log (1)……………………………………………………21

FIGURE 5: Geotechnical Borehole Log (2)…………………………………………………....23

FIGURE 6: Site Layout………………………………………………………………………...33

LIST OF PLATES

PLATE NUMBER PAGE

PLATE 1: Sounding Rod (1M) and Cone…………………………………………………….10

PLATE 2a: Showing activity on site……………………………………………………….....11

PLATE 2b: Showing activity on site……………………………………………………….....11

CHAPTER ONE

INTRODUCTION

BRIEF HISTORY OF SIWES

SIWES was established by ITF in 1973 to solve the problem of lack of adequate practical skills

preparatory for employment in industries by Nigerian graduates of tertiary institutions.

The Scheme exposes students to industry based skills necessary for a smooth transition from the

classroom to the world of work. It affords students of tertiary institutions the opportunity of being

familiarized and exposed to the needed experience in handling machinery and equipment which

are usually not available in the educational institutions.

Participation in Industrial Training is a well-known educational strategy. Classroom studies are

integrated with learning through hands-on work experiences in a field related to the student’s

academic major and career goals. Successful internships foster an experiential learning process

that not only promotes career preparation but provides opportunities for learners to develop skills

necessary to become leaders in their chosen professions.

One of the primary goals of the SIWES is to help students integrate leadership development into

the experiential learning process. Students are expected to learn and develop basic non-profit

leadership skills through a mentoring relationship with innovative non-profit leaders.

By integrating leadership development activities into the Industrial Training experience, we hope

to encourage students to actively engage in non-profit management as a professional career

objective. However, the effectiveness of the SIWES experience will have varying outcomes based

upon the individual student, the work assignment, and the supervisor/mentor requirements. It is

vital that each internship position description includes specific, written learning objectives to

ensure leadership skill development is incorporated.

Participation in SIWES has become a necessary pre-condition for the award of Diploma and

Degree certificates in specific disciplines in most institutions of higher learning in the country, in

accordance with the education policy of government.

Operators - The ITF, the coordinating agencies (NUC, NCCE, NBTE), employers of labor and the

institutions.-

Funding - The Federal Government of Nigeria

Beneficiaries - Undergraduate students of the following: Agriculture, Engineering, Technology,

Environmental, Science, Education, Medical Science and Pure and Applied Sciences.

Duration - Four months for Polytechnics and Colleges of Education, and Six months for the

Universities.

The following are some of the objectives of SIWES:

1. SIWES will provide students the opportunity to test their interest in a particular career before

permanent commitments are made.

2. SIWES students will develop skills in the application of theory to practical work situations.

3. SIWES will provide students the opportunity to test their aptitude for a particular career before

permanent commitments are made.

4. SIWES students will develop skills and techniques directly applicable to their careers.

5. SIWES will aid students in adjusting from college to full-time employment.

6. SIWES will provide students the opportunity to develop attitudes conducive to effective

interpersonal relationships.

7. SIWES will increase a student's sense of responsibility.

8. SIWES students will be prepared to enter into full-time employment in their area of

specialization upon graduation.

9. SIWES students will acquire good work habits.

10. SIWES students will develop employment records/references that will enhance employment

opportunities.

11. SIWES will provide students the opportunity to understand informal organizational

interrelationships.

12. SIWES will reduce student dropouts.

13. SIWES Students will be able to outline at least five specific goals with several staff members

by comparing performance with job duties and develop a draft plan with staff to accomplish

performance needs, supervision plan and rewards.

14. SIWES Students will be able to develop a draft agency or project budget and will be able to

identify methods of obtaining revenue to support the budget.

15. SIWES Students will be able to provide tools to use in prioritizing tasks of an assigned project

and create with staff a tentative schedule for completion based on these tasks.

16. SIWES Students will be able to develop a model policy that gives current front-line leaders

the permission and expectation to work with other staff on conflict resolution and explain how this

works to current front line leaders.

17. SIWES Students will be able to describe different skills leaders can use to Foster commitment

and collaboration with both internal and external constituents.

The 6 months Students Industrial Work Experience Scheme (SIWES) which is a requirement for

the completion of my course of study, Geology, was undertaken at KDF KONSULT LIMITED

located at 3, Balogun Street, Ikeja, Lagos state. The company functions to provide a professional,

efficient and sustainable geotechnical assessment, survey, report, and training.

CHAPTER TWO

2.1 KDF KONSULT LIMITED COMPANY PROFILE

KDF KONSULT LIMITED is a geotechnical and engineering company which has its head office

at NO. 3, Balogun Street, Ikeja, Lagos State. The company has a professional experience in the

application of scientific principle to engineering problems. As professionals, the engineers,

geologists, surveyors in the company owe a duty to the public as well as to their clients who receive

the final product; a final product that retains the same professional characteristics that meets the

professional standard. The company has extended the scope of the services rendered because of

the presence of the Industrial Training students so that we may actually appreciate the importance

of site supervision and borehole management as IT students.

Kdf Konsult Limited is a leading service provider in Geotechnical, Mining, Dredging, Water and

Environmental Engineering, Servicing and Construction sector using the best resources available

to maximize is returns and create positive impact in the industry. The company presently has client

spanning different sectors. These include:

Construction

Oil and Gas

Telecommunications

Financial Institutions

Government Parastatals

Net worth Individuals and more

2.2 BRIEF HISTORY OF KDF KONSULT LIMITED

KDF Konsult Ltd was established in 2002 and actually started full operation in 2003. Our company

was deliberately fashioned out, to focus on Engineering services, General Procurements and

Project Support Services.

We have a team of competent registered professionals with broad and deep experience in business

engineering and safety/ environmental field.

We have records of breakthrough and we are waxing stronger in proving services with diligence

and excellent level of practice. Our human resources development, structures and background gave

us ample opportunity to deal professionally in various field of life jointly with our technical partner.

Our simple profile reflects the summary of our key staff, that of our technical partner, and our

achievements in practice as individuals when working with previous bigger organization and as a

group now working in KDF Konsult Ltd.

2.3 DEPARTMENT OF THE COMPANY

The various departments in KDF KONSULT LTD include:

Administrative department

Human resources

Finance

Geotechnical Engineering and Piling

Maintenance

Geological

Quality assurance

Civil Engineering

Environmental Consulting

Fibre Optics

2.4 THE ORGANIZATIONAL STRUCTURE OF KDF KONSULT LTD

FIGURE I: ORGANIZATIONAL CHART

CHAPTER THREE

3.0 ACTIVITIES AT KDF KONSULT LIMITED

3.1 ACTIVITY 1: SUBSOIL INVESTIGATION

INTRODUCTION

Subsoil investigation is essential before any construction work is done on any land.

The purpose of the subsoil investigation include the following:

Determination of the subsoil and surface/groundwater conditions of the designated

location.

Evaluation of the subsoil stratigraphic sequence geotechnical/engineering

properties of the soil and the subsequent effects on foundation design and

construction.

Analysis of the data/results of tests carried out on the soil samples obtained and

provide recommendations on the fit-for-purpose and economic type of foundation

for the proposed structure.

To disclose and make provisions for difficulties and anomalies that may arise

during construction due to ground and other local conditions.

3.1.1 PROCESS AND RESULT

INTRODUCTION

DUTCH CONE PENETROMETER

The apparatus consists of a cylindrical probe, of 1000mm2 cross sectional area, and a conic head of apex

angle of 60o attached to a rod enclosed by an outer sleeve. The probe is forced down through the soil at a

steady rate of about 20mm/s in the closed position by exerting pressure force on outer sounding tube. If

desired the point resistance and the resistance to side friction can be measured separately. Although

originally designed for pile design, the cone penetrometer has also been used to estimate bearing capacity

and settlement of foundations. The results from CPT can be correlated with lab test results and other field

tests (usually Standard Penetrometer Tests) to build empirical relationship for soil strength and deformation

parameters. However, CPT is quick to perform with fewer performance error compared to SPT and can

provide continuous record of soil condition.

The machine consists of the following:

Sounding rods

Push/pull adaptor

Spiral anchor

Handle and T-piece

Mantle cone

Wrenches set

Testometer

FIGURE 2: 2.5 Ton Penetrometer PLATE 1: Cone and Rod

Six static cone penetration tests were carried out using a 2.5 Ton capacity testing equipment (machine) on

each point. The test involves advancing the cone into the ground slowly at a constant rate and the resistant

to penetration measured at predetermined intervals of 0.20m depth. The tests were terminated at depths

where the machine anchor legs lifted.

These tests were taken from the existing ground level down to depths of -5.00m in Pen1, -3.50m in Pen 2,

-4.00m in Pen 3, -4.25m in Pen 4, -4.00m in Pen 5 and -3.50m in Pen 6.

PLATE 2a; showing work on site PLATE 2b; showing work on site

SUBSOIL CONDITION

The subsoil condition of the site, based on the DCP and Borehole/SP carried out reveals

predominantly cohesive soil as observed from the DCP Plot and Borehole log.

Details of the subsoil characteristics encountered during the Penetrometer tests and Borehole/SP

test:

Soil Profile

Depth (m) Description of Stratum

0.00 to –.0.75 Dark brown cohesionless soil.

0.75 to –2.00 Firm to stiff cohesive soil.

2.00 to –5.00 Stiff to very stiff cohesive soil.

GEOTECHNICAL PROPERTIES

Depth (m) Geotechnical Properties

0.00 to –.0.75 Moderate geotechnical properties, moderate shear strength and

moderate compressibility potential.

0.75 to –2.00 Moderate to good geotechnical properties, moderate to high shear

strength and low compressibility potential.

2.00 to –5.00 Good geotechnical properties, high shear strength and low

compressibility potential

GEOTECHNICAL ENGINEERING PARAMETERS

Depth (m) P1 P2 P3

0.00 – 0.75m 5 – 10 14 – 26 12 – 15

0.75 – 2.00m 13 – 17 38 – 56 20 – 38

2.00 – 5.00m 23 – 152 74 – 147 44 – 152

Depth (m) P4 P5 P6

0.00 – 0.75m 15 – 18 10 – 20 15 – 18

0.75 – 2.00m 19 – 41 25 – 42 18 – 62

2.00 – 5.00m 48 – 150 54 – 156 60 – 148

SITE LOCATION

Several subsoil investigations were carried out during my time with KDF KONSULT LIMITED.

Presented in this paper is a case study on a site located at Muritala Mohammed Airport Way (Int`l),

off Concord Way, Ikeja, Lagos State. The project site is an open piece of land within residential

and commercial environment. Structures around site show no sign of distress at the time of our

investigation.

GEOLOGY OF THE AREA

Geologically, the site falls within the formation called the coastal plain sands. This formation has

a recent deposit called the alluvial deposit on it. Sands, clays and lignite, sometimes mixtures of

these constitute the material that makes up this formation.

GROUNDWATER CONDITION

Groundwater was encountered at depth 0.25m to 1.60m during the subsoil investigation. This level is

subjected to variation due to season.

RESULT ANALYSIS AND INTERPRETATION

PENETROMETER 1

PENETROMETER 2

PENETROMETER 3

PENETROMETER 4

PENETROMETER 5

PENETROMETER 6

3.1.2 SKILS AND KNOWLEDGE ACQUIRED

I got familiarized with the soil testing apparatus, its parts, and mode of operation.

Ability to effectively carry out subsoil investigation given the necessary tools.

Mentality of working with others (team work) was greatly developed.

3.2 ACTIVITY 2; GEOTECHNICAL BOREHOLE DRILLING

INTRODUCTION

STANDARD PENETRATION TESTS

Standard penetration tests (abbreviated as SPT) are used mainly in non-cohesive soils, but occasionally

also in cohesive soils as a means of determining density or strength and also of obtaining a relatively

undisturbed sample.

The test is carried out in a borehole by driving a 50 mm diameter split sample tube under the impact of a

63 kg hammer with a free fall of 760 mm. It is normal for the tube to be driven in three successive 150

mm increments and the ‘N’ value is taken as the number of blows for the last 300 mm. In dense sands,

very hard clays or weak rock, the full 450 mm penetration may not be practicable and the test is

discontinued.

FIGURE 3: GEOTECHINCAL BOREHOLE MACHINE SCHEMATIC

The test results are reported in the following form:

• In the case where full penetration is obtained with successive blow counts for each 150 mm of say 4, 6

and 7 as 4, 6, 7 ~`N = 13

• In the case where the test is discontinued short of full penetration, say after 15 blows for the first 150

mm and 30 blows for the next 40 mm as 15, 30/40 mm.

The results of the tests can be related empirically to the engineering properties of the soil.

Occasionally, the test method is used to obtain samples in 50 mm diameter thin walled sample tubes in

clays. In such circumstances, the test results are shown on the bore logs in brackets.

SITE LOCATION

The site is located at Muritala Mohammed Airport Way (Int`l), off Concord Way, Ikeja, Lagos

State. The project site is an open piece of land within residential and commercial environment..

Structures around site show no sign of distress at the time of our investigation.

3.2.1: PROCESS AND RESULT

GEOLOGY OF THE AREA

Geologically, the site falls within the formation called the coastal plain sands. This formation has a recent

deposit called the alluvial deposit on it. Sands, clays and lignite, sometimes mixtures of these constitute the

material that makes up this formation.

RESULT ANALYSIS AND INTERPRETATION

BOREHOLE 1

BOREHOLE/SPT TEST


0.00 to 1.00 Brown silty sand with clay binder.

1.00 to 6.75 Firm to stiff brown silty sandy CLAY.

6.75 to 12.75 Stiff to very stiff grey silty sandy CLAY with gravels

12.75 to 20.00 Medium dense to dense brown fine and medium SAND.


Depth (m)

Geotechnical Properties

0.00 to 1.00 Moderate to good geotechnical properties, moderate shear strength

and moderate compressibility potential.

1.00 to 6.75 Moderate to good geotechnical properties, moderate to high shear


6.75 to 12.75 Good to very good geotechnical properties, high shear strength

and low compressibility potential




FIGURE 4: GEOTECHNICAL BOREHOLE LOG (1)

Depth (m) N-value U4 sample

0.00 – 1.00m - -

1.00 – 6.75m - Retrieved at 3.00m and

6.00m

6.75 – 12.75m 14 - 16 Abortive

12.75 – 20.00m 20 - 32 N/A

BOREHOLE 2

BOREHOLE/SPT TEST


0.00 to 0.75 Dark brown silty sand with clay binder.

0.75 to 6.00 Firm to stiff grey silty sandy CLAY with gravels.

6.00 to 12.75 Medium dense to dense brown fine and medium SAND

12.75 to 16.50 Stiff brownish grey silty CLAY with sand at the bottom part.

16.50 to 20.00 Medium dense to dense brown fine and medium SAND


Depth (m)

Geotechnical Properties

0.00 to 0.75 Moderate geotechnical properties, moderate shear strength and

moderate compressibility potential.

0.75 to 6.00 Moderate to good geotechnical properties, moderate to high shear


6.00 to 12.75 Good geotechnical properties, high shear strength and low


12.75 to 16.50 Good geotechnical properties, high shear strength and low





FIGURE 5: GEOTECHNICAL BOREHOLE LOG (2)

Depth (m) N-value U4 sample

0.00 – 0.75m - -

0.75 – 6.00m - Retrieved at 3.00m

6.00 – 12.75m 14 - 16 Abortive

12.75 – 16.50m 20 - 32 N/A

16.50 – 20.00m 20 - 32 N/A

LABORATORY ANALYSIS

PROPOSED DEVELOPMENT AT MURITALA MOHAMMED AIRPORT ROAD LAGOS.

Samples are normally taken from the field for laboratory analysis to characterize the physical and mechanical

properties if soil strata. These parameters are used to design foundations and to evaluate the application of soils as

construction materials.

Disturbed samples (such as from Standard Sampler) are usually used for visual inspection and for tests to

determine the physical properties such as grain size, grain shape, and plasticity.

Undisturbed samples (such as from Thin-Walled Sampler) are used for both physical and mechanical assessment.

Test results, especially mechanical, are strongly affected by sampling, handling, transportation, and sample

preparation disturbances.

Care must be taken to protect the intact condition of soil samples. Wax is often used to coat soil samples to

prevent moisture loss.

LABORATORY ANALYSIS TABLE

BH No

Sample No

Depth

(m)

Soil Type

Moisture content %

Specific gravity

Cu

Ø

1

5

3.00

C

28

2.06

175

13

2

5

3.00

C

29

2.11

190

12

BH 1 Sample: 5 Depth: 3.00m

Undrained Cohesion 175KN/m2

Angle of Friction (PHI) 13 deg

BH 2 Sample: 5 Depth: 3.00m

Undrained Cohesion 190KN/m2

Angle of Friction (PHI) 12 deg

0

200

400

0 50 100 150 200 250 300 350 400 450 500 550 600 650 700 750 800 850 900 950 1000Sh

ear

Str

ess,

KN

/m2

Total Normal Stress, KN/m2

0

200

400

0 50 100 150 200 250 300 350 400 450 500 550 600 650 700 750 800 850 900 950 1000Sh

ear

Str

ess,

KN

/m2

Total Normal Stress, KN/m2

4.1.1 Proposed Development

No structural detail of the proposed development was made available to us prior to the subsoil

Investigation, thus our recommendations are based on the DCP and Borehole/SPT carried out.

The geotechnical issues considered relevant to the proposed development include

Soil bearing pressure

Level of groundwater

Recommendation of a suitable foundation type

RECOMMENDATION

The foundation type to be chosen for a particular structure depends largely on the followings;

- Loads to be transmitted

- Receiving soil strata

- Factor of safety against shear failure of the supporting soil must be adequate.

- Settlement should neither cause any unacceptable damage nor interfere with the function

of the structure.

Foundations can be classified as shallow foundation or as deep foundation.

The choice between shallow foundation and deep foundation can be arrived at after careful

consideration of the following elements:

1. The magnitude of the transmitted loads from the stratum,

2. The soil nature,

3. The economic aspects of the elements of the foundation work,

4. Problems concerning foundation construction.

Allowable bearing pressure calculated between ground surface and -3.00m

Allowable bearing pressure calculated in accordance with theoretical soil mechanics principle for depths

are indicated below:

KPA VALUES:

Differential Depth (m) Allowable bearing Capacity (KN/m2)

0.00 – 1.00 132

1.00 – 2.00 186

2.00 – 3.00 390

METHOD OF CALCULATING ALLOWABLE BEARING PRESSURE IN COHESIVE SOIL IS

GIVEN BY:

Empirical Method for calculating in Cohesive Soil is given by:

qult = 5.14Cu + ϪD (Prandtl method of estimating allowable bearing pressure)

qa= qult/F.S (3) – For Shallow foundation

If the Clay is very Sandy

Correlation between qc and SPT (N – Values)

N = qC / 2

qa = 10N, or 5.0N (If Submerged)

Correlation between qc and Cu

Cu = qc / 20 (KN/m2)

METHOD OF CALCULATING ALLOWABLE BEARING PRESSURE IN COHESSIONLESS

SOIL IS GIVEN BY:

qa = 2.7qc .Rw2 (Meyerhof method) (for all width of foundation and limit settlement to 25mm)

If Reinforced Raft Foundation is to be adopted qa calculated above could be doubled.

Correlation between qc and SPT (N – Values) in Cohessionless Soil

N = qC / 4 = N

qa = 10N, or 5.0N (If Submerged)

FOUNDATION RECOMMENDATION

The selection of parameters for foundation design should take into account the extent, quality and

adequacy of the ground investigation, reliability of the geological and geotechnical analysis model, the

appropriateness of the test methods, the representativeness of soil parameters for the likely field

conditions, the method of analysis adopted for the design, and the likely effects of foundation

construction on material properties. In principle, sophisticated analyses, where justified, should only be

based on high quality test results. The reliability of the output is, of course, critically dependent on the

representativeness and accuracy of the input parameters.

'Best-estimate' parameters, which are those representative of the properties of the materials in the field,

should be selected for design. Engineering judgment is always required in the interpretation of test results

and in the choice of design parameters, having regard to previous experience and relevant case histories.

In adopting well-established correlations for a given geological material, it is important to understand

how the parameters involved in the database for the particular correlation have been evaluated. In

principle, the same procedure in determining the parameters should be followed to safeguard the validity

of the correlations.

Shallow foundation

Shallow Foundation (Stiffened Raft Slab) is considered adequate for the proposed development on the

project site.

Stiffened Raft Slab helps to minimize differential settlement.

Settlement

Settlement for this allowable bearing pressure stated above would not exceed 50mm.

Our analysis on settlement is based on the method stated below

S = 1.1Mv x 0.55qn x h

Where S = Total settlement

Mv = Volume of compressibility potential

qn = net foundation base pressure

h = depth of foundation

The table below shows the permissible settlement as per I.S Code.

Soil type

Permissible total settlement

Permissible differential settlement

For isolated

footings

For raft footings

For isolated

footings

For raft footings

Sandy

4.0cm

4.cm to 6.5cm

2.5cm

2.5cm

Clays

6.5cm

6.5 to 10.0cm

4.0cm

4.0cm

Factor of Safety

Factor of safety of 3 was adopted for the estimation of allowable bearing pressure.

Excavation

Adequate preparation should be put in place to excavate into brown silty sandy clay

Excavation could be achieved using conventional excavating equipment.

Excavation support would not be required

General Precaution for Shallow Foundation Construction

It is recommended that the following general guidelines that govern the construction of shallow

foundation should be observed when work starts on the site:

Over excavation beyond the depths stated should not be done.

Ingress of water into the excavated foundation trench should be prevented if the stated

bearing value at the founding depth is to be achieved. A layer of concrete blinding should

therefore be provided within a trench once it has been excavated.

Adequate cover to the concrete should be allowed for the reinforcement bars to protect

them from possible effect of corrosion.

The sides of foundation should be backfilled up to existing ground level as soon as they are

cast.

CONCLUSION

Shallow Foundation (Stiffened Raft Slab) is considered adequate for the proposed development on

the project site.

Stiffened Raft Slab helps to minimize differential settlement.

Despite an objective soil investigation and reporting, a poorly designed and/or constructed

foundation may lead to structural failure if all other environmental conditions remain constant.

3.2.2 SKILS AND KNOWLEDGE ACQUIRED

I got familiarized with the soil testing apparatus (SPT), its parts, and mode of operation.

Ability to effectively carry out subsoil investigation (SPT) given the necessary tools.

Mentality of working with others (team work) was greatly developed.

SUMMARY

Geotechnical reports are based on information gained from limited subsurface test boring and

sampling, supplemented by knowledge of local geology and experience.

Description and Classification Methods

In general, descriptions cover the following properties - strength or density, colour, structure, soil

or rock type and inclusions.

Soil types are described according to the predominating particle size, qualified by the grading of

other particles present (e.g. sandy clay) on the following bases:

Soil Classification Particle Size

Clay = less than 0.002 mm

Silt = 0.002 to 0.06 mm

Sand = 0.06 to 2.00 mm

Gravel = 2.00 to 60.00 mm

Cohesive soils are classified on the basis of strength either by laboratory testing or engineering

examination.

The strength terms are defined as follows.

Classification Undrained Shear Strength kPa

Very soft less than 12

Soft 12—25

Firm 25—50

Stiff 50—100

Very stiff 100—200

Hard Greater than 200

Non-cohesive soils are classified on the basis of relative density, generally from the results of

standard penetration tests (SPT) or Dutch cone Penetrometer tests (CPT) as below:

Relative Density SPT “N” Value (blows/300 mm)

CPT Cone Value (qc — MPa)

Very loose less than 5 less than 2

Loose 5—10 2—5

Medium dense 10—30 5—15

Dense 30—50 15—25

Very dense greater than 50 greater than 25

Rock types are classified by their geological names. Where relevant, further information

regarding rock classification is given.

Sampling

Sampling is carried out during drilling to allow engineering examination (and laboratory testing

where required) of the soil or rock. Disturbed samples taken during drilling provide information

on colour, type, inclusions and, depending upon the degree of disturbance, some information on

strength and structure.

Undisturbed samples are taken by pushing a thin walled sample tube into the soil and

withdrawing with a sample of the soil in a relatively undisturbed state. Such samples yield

information on structure and strength, and are necessary for laboratory determination of shear

strength and compressibility. Undisturbed sampling is generally effective only in cohesive soils.

FIGURE 6: SITE LAYOUT

CHAPTER FOUR

SUMMARY

The benefits of the (SIWES) Programme is that it helped me to be acquainted with major activities

carried out in the geological industry and to appreciate the practical view of my study , especially

as regards geotechnical operations.

4.1 Main Activities

I was assigned to the geotechnical (subsoil investigation) department were I was taught on the

essence and methodology of soil testing using Dutch Cone Penetrometer (2.5 TON and 10 TON).

Some of the tools and terms that I familiarised myself with include:

Drilling rig : the machine used to drill a wellbore,the rig includes mud tanks,mud pumps, derrick,

rotary table, drill string, power generator equipment and auxilary equipment in other words it is a

package of special equipment put together to enable us drill into the earth.

Dutch Cone Penetrometer : apparatus/machine used to carry out subsoil investigation.

Probe (Rod) : one meter long metal attached to the cone and forced into ground.

Anchor : CPT machine legs used for stability of machine during operation.

water table : A level beneath the Earth's surface, below which all pore spaces are filled with water

and above which the pore spaces are filled with air aquifer.

4.2 BENEFITS AND CHALLENGES

BENEFITS

The benefits of the SIWES programme is that it helped me to be acquainted with most major

activities carried out in the geoscience world and to appreciate the practical view of my syudy,

especially as regards geotechnical operations, and also helped me improve in the area of

socialization.

CHALLENGES

The problems I encountered are listed below:

I. Though I was among the few students that found a place to work, it took some weeks

before I took part in the executions of project.

II. Unfavourable weather conditions sometimes obstruct smooth execution of projects.

III. More projects came at the time of my departure that I could have benefitted from.

4.3 RECOMMENDATION

For subsequent trainees being taken up by the company, I strongly recommend a more stringent

supervision of their training program, especially by the industry based SIWES supervisor. This

will go a long way in ensuring that trainees do not lose focus and will constantly remind them that

their services to the company remain valuable.

Also I suggest ITF should liaise with some companies where they will take up students for

industrial training. This will help students who find it difficult to find attachments or who end up

in companies where they do nothing.

4.4 LESSONS/SKILLS ACQUIRED

After my internship with KDF KONSULT LIMITED :

• I can effectively carry out soil testing usina a Dutch Cone Penetrometer.

• I can process raw Qc values from site

• I can accurately give recommendation on foundation design.

CHAPTER FIVE

CONCLUSION

This Industrial Training has afforded me the basic practical and theoretical knowledge that I may

not have gotten from the lecture room. It also gave me the opportunity to have a feel of what life

after school is like.

After my internship with KDF KONSULT LIMITED :

• I can effectively carry out soil testing usina a Dutch Cone Penetrometer.

• I can process raw Qc values from site

• I can accurately give recommendation on foundation design.

Other benefits include:

Good working ethics as a result of the close working relationship I had with the geologists and

engineers. These ethics include being able to handle situation with little or no help, being able to

provide solutions to lingering problems, etc.

I have been able to use this training to explore various avenues available at my disposal career-

wise. It has given me the opportunity to have a look into the future and assess my readiness for

employment or entrepreneurship.

SIWES (IT) REPORT ON SUBSOIL INVESTIGATION (GEOTECHNICAL ASSESSMENT)

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