VALUE ENGINEERING STUDY ON DRAINAGE DESIGN IN SLOPE

Jude Ting Mui Heng

Master of Engineering

(Civil Engineering)

2014

APPROVAL SHEET

The project report which entitled “Value Engineering Study on Drainage Design in

Slope”, was prepared by Jude Ting Mui Heng (14030076) is hereby read and approved

by:

_____________________________________ ______________

Associate Professor Dr. Nasser Rostam Afshar Date

(Supervisor)

VALUE ENGINEERING STUDY ON DRAINAGE DESIGN IN SLOPE

JUDE TING MUI HENG

Thesis is submitted to

Faculty of Engineering, Universiti Malaysia Sarawak

In Partial Fulfillment of the Requirements

For the Master of Engineering

(Civil Engineering)

2014

ii

To my beloved family and friends.

iii

ACKNOWLEDGEMENT

My utmost gratitude goes to my main and co-supervisors, Assoc Prof Dr Nasser

Rostam Afshar and Dr. Onni Suhaiza binti Selaman for their guidance, kindness, time,

moral, scientific support and most of all, for their patience in all the time of research

and writing of this thesis.

I would like to express my gratitude to staff of Kumpulan IKRAM Sdn Bhd,

Mr. Kamarudin for willing to share information about the slope management in

Malaysia. Not to forget Assoc Prof Dr Siti Noor Linda Taib for having a weekly

meeting on slope discussion which has solve most of the doubts that have in slope

especially the horizontal drain design in slope.

My appreciation goes to the Civil Engineering Department at Faculty of

Engineering Universiti Malaysia Sarawak for the support in my. Lastly, I would like to

express my gratitude to Universiti Malaysia Sarawak (UNIMAS) for providing me the

facilities and equipment for the completion of my study.

iv

ABSTRACT

This study evaluate the value of horizontal drain in slope using value

engineering process. The main focus in this study is to achieve the high value of

horizontal drain in slope. The usage of horizontal drain is one of the methods that

used to lower the high ground water table and hence stabilize the slope. Several

elements in the slope is evaluate and the horizontal drain in the slope is studied

on its value. The value of the installation of horizontal drain are investigates

through sets of different types of pipes.

Others components in slope such as degree of slope, drainage filter and

vegetations are studied as well. The combination of different components in the

slope is analyzed. Total proposed of 48 alternative design using different

combination are studied with their value.

From the evaluations obtained from the research, it can be concluded that the

pipe that being used in the initial design which is 75mm "Class D" UPVC can be

replaced by HDPE Grade PN 10 which will increase the value as much as

13.42%. However, the recommendation is given to the combination of the

alternative design which give the increase value as much as 15.77 % by

replacement of slope degree from 25o to 35

o and 75mm "Class D" UPVC to

HDPE Grade PN 10. This study also found that with the increase of slope from

25o to 35

o will cost 35.32 %more on vegetation which will only increase the

value by 1.85%.

`

v

ABSTRAK

Kajian ini menilai nilai paip mendatar di cerun menggunakan proses Value

Engineering. Fokus utama kajian ini adalah untuk mencapai nilai yang tinggi dalam

paip mendatar di cerun. Penggunaan paip mendatar adalah salah satu kaedah yang

digunakan untuk menurunkan aras air tanah yang tinggi dan menstabilkan cerun.

Beberapa elemen dalam cerun dinilai dan paip mendatar di cerun dikaji pada nilainya.

Nilai pemasangan paip mendatar dalam cerun disiasat dengan pelbagai set jenis paip.

Komponen lain dalam cerun seperti sudut cerun, kain pembalut paip dan jenis

tumbuhan juga dikaji dalam kajian ini. Gabungan daripada komponen yang berbeza

di dalam cerun dianalisis. Sebanyak 48 alternatif gabungan rekabentuk dicadangkan

dengan menggunakan pelbagai gabungan dan nilai setiap alternatif rekabentuk dikaji

nilainya.

Dari penilaian yang diperolehi daripada kajian ini, dapat disimpulkan bahawa

paip yang digunakan dalam cerun pada mulanya iaitu 75mm "Kelas D" UPVC boleh

digantikan dengan pipe HDPE PN Gred 10 yang akan meningkatkan nilai sebanyak

13.42%. Walaubagaimanapun, gabungan altenatif yang disyorkan ialah pengantian

sudut cerun dari 25o kepada 35

o dan paip 75mm "Kelas D" UPVC kepada paip 75mm

HDPE PN Gred 10 yang memberikan nilai peningkatan sebanyak 15.77%. Kajian ini

juga mendapati degan meningkatkan sudut cerun dari 25o kepada 35

o akan

memberikan kos 35.32 % lebih kepada rumput di cerun dengan hanya peningkatan

nilai sebanyak 1.85%.

vi

TABLE OF CONTENT

Page

Acknowledgement iii

Abstract iv

Abstrak v

Table of Contents vi

List of Tables ix

List of Figures x

List of Abbreviations xi

List of Symbols xii

CHAPTER 1 INTRODUCTION

1.1 General Review 1

1.2 Problem Statement 4

1.3 Aims of Study 5

1.4 Project Aims and Objectives

1.5 Scope of Study

5

5

1.6 Structure of Outline 5

CHAPTER 2 LITERATURE REVIEW

2.1 General Review of Landslide 7

2.2 Landslides Classification 8

2.3 Factors Affecting the Slope Stability 11

2.4 Horizontal Drain in Slope 12

2.5 Types of Horizontal Drain 13

2.5.1 Corrugated Aluminium Alloy Pipes 13

vii

2.5.2 Perforated Plastic (PVC or HDPE) 14

2.5.3 Concrete Pipes 15

2.5.4 Clay Pipes 15

2.6 Type of Vegetations 16

2.7 Economic Costs for Landslides 18

2.8 Introduction of Value Engineering 21

2.9 Study on Component in the Compass using Value

Engineering 23

2.10 Previous Study on Value Engineering 24

CHAPTER 3 METHODOLOGY

3.1 Introduction 26

3.2 Flow Diagram 27

3.2.1 Information 27

3.2.2 Function Analysis 28

3.2.3 Creativity 28

3.2.4 Evaluation 28

3.2.5 Develop Ideas 29

3.2.6 Presentation 29

3.3 Case Study Selection 29

3.4 Fast Diagram of Slope 30

CHAPTER 4 RESULTS, ANALYSIS AND DISCUSSION

4.1 Information 31

4.2 Component in Drainage Design of Slope 34

4.2.1 Slope 34

4.2.2 Drainage Pipe 35

4.2.3 Drain Envelope 35

4.2.4 Vegetation 36

4.2.5 Soil Material 37

4.3 Creativity 37

4.4 Evaluations 38

4.5 Development of Ideas 40

viii

4.6 Benefit Calculations of Horizontal Drains 43

4.7 Cost of Different Components 44

4.7.1 Horizontal Drains 44

4.7.2 Drainage Filter 45

4.7.3 Vegetation 45

4.8 Data Analysis 45

4.9 Ranking for B/C Value of the Alternative Design 48

4.10 Comparison of the Component with Initial Design 49

4.11 Determination of the Vital Component in Slope 51

CHAPTER 5 CONCLUSIONS AND RECOMMENDATIONS

5.1 Conclusions 53

5.2 Suggestions for Future Works 54

REFERENCES 55

APPENDIXES

Appendix A: Tencate Polyfelt Brochure 58

Appendix B: Cost of Components 60

ix

LIST OF TABLES

Table Page

2.1 Classification of Landslide Suggested by Varnes (1978) 9

2.2 Classification of Velocity of Movement According to Cruden

and Varnes (1996) and Australia Geomechanics Society (2002)

10

2.3 Factors that Cause Increases in Shear Stresses in Slopes 11

2.4 Factors that Cause Reduced Shear Strength in Slopes 12

2.5 Landslides in Malaysia (1973-2007) with Economic Costs

Exceeding RM 15 Million

20

2.6 Component and Functions of a Compass (Centre for Technology

Transfer and Consultancy, UNIMAS)

23

4.1 Details of the Studied Slope 33

4.2 Elements and Functions in Slope 34

4.3 Specification of Filter Cloth (JKR) 36

4.4 Common Values for Tropical Residual Soils (ICCBT 2008-E-

(04)-pp33-42)

37

4.5 Comparison of Method of Slope Stabilization 38

4.6 Alternatives Combinations of Component in Slope 42

4.7 Cost of Alternatives Horizontal Drain in Slope 44

4.8 Cost, Saving and B/C for Alternatives Design 46

4.9 Ranking for the B/C of Alternative Design 48

4.10 Value Difference with Initial Design 50

4.11 Components which Increase the Value 51

x

LIST OF FIGURES

Figure Page

2.1 Corrugated Aluminium Alloy Pipe (Qingdao Chemetals

Industries)

14

2.2 Perforated Plastic (PVC or HDPE), Shangdong Yanggu

Hengtai Industrial Co

14

2.3 Concrete Pipes (CPM Drainage) 15

2.4 Clay Pipes (GBH Clay Pipes) 16

2.5 Axonopus Compressus (Cow Grass), Hok Hing Trading 17

2.6 Pearl Grass, Hok Hing Trading 17

2.7 Annual Economic Costs due to Landslides from 1973 to 2007.

(National Slope Master Plan)

19

3.1 Step of Value Engineering Process 27

3.2 Fast Diagram of Slope 30

4.1 Locality of Landslide (Source: Google Maps) 32

4.2 Detailed Information (Source: Google Maps) 33

4.3 Cross Section of Slope Studied 35

4.4 Horizontal Drains Locations, Resistivity and Seismic Survey

Lines

41

xi

LIST OF ABBREVIATIONS

BEM - Board of Engineers Malaysia

PWD - Public Work Department

JKR - Jabatan Kerja Raya

VE - Value Engineering

PVC - Polyvinyl Chloride

HDPE - High-Density Polyethylene

WSDOT - Washington State Department of Transportation

UNIMAS - Universiti Malaysia Sarawak

U.S - The United States

GAO - Government Accountability Office

EPA - Environmental Protection Agency

TIA - Taoyuan International Airport

UPVC - Unplasticized Polyvinylchloride

ABS - Acrylonitrile Butadine Styrene

RM - Malaysia Ringgit

xii

LIST OF SYMBOLS

et al. - and others

e.g - example given

m - Meter

sec (s) - Second

Co - Company

Ʃ - Total

o - Degree

% - Percentage

ɣ - Unit Weight

c' - Cohesion

ɸ' - Effective Friction Angle

k - Saturated Permeability

H - Slope Height

tan β - Slope Inclination

con't - Continue

1

CHAPTER 1

INTRODUCTION

1.1 General

Slope is "vertical change" divided by the "horizontal change" between (any) two

distinct points on a line. A slope is simply an inclined ground separating two

different ground levels. Joining of two different levels will be an inclined ground we

call “the slope”. In Engineering, ways to describe how steep the slope is by the angle

in degrees, and the other is by the slope in a percentage.

The slope can be nature or manmade. The common examples of natural slope are

hills, mountains, riverbanks and coastal formation. Embankments, earth dam,

foundation excavation and trenches are manmade slope.

Landslides, slips, slumps, mudflows, rock falls are just some of the terms which are

normally used to describe movements of soils and rocks under the influence of

gravity. Many systems of classification for the different types of slope instability

have been proposed. These include the notable schemes by Sharpe (1983), Varnes

2

(1958) and Hutchinson (1967a) to which Skemptom and Hutchinson (1969) give a

comprehensive list of illustrative case records. We can divide the mass movement

into three major classes: slides, falls and flows. The major differences between these

three are in the way in which movement takes place.

In a slide, the moving material remains largely in contact with the parent or

underlying rocks during the movement, which takes place along a discrete boundary

shear surface. The term flow is used when the material becomes disaggregated and

can move without the concentration of displacement at the boundary shear. Lastly,

falls normally take place from steep faces in soil or rock, and involve immediate

separation of the falling material from the parent rock or soil mass, with movement

involving only infrequent or intermittent contact thereafter, until comes finally to

rest.

A slope failure is a phenomenon that a slope collapses abruptly due to weakened

self-retain ability of the earth under the influence of a rainfall or an earthquake.

When a slope near a roadway were to fail and block the road, it will cause some

traffic disruption. Where in a serious case where people live and the slope were to

fail, they would not only be traffic disruption and damages but likely loss of lives.

Because of sudden collapse of slope, many people fail to escape from it if it occurs

near a residential area, thus resulting in a higher rate of fatalities.

Attention was dramatically focused on the problem of the stability of slopes over the

years since the collapse of Tower 1 of Highland Towers in 11th

December 1993 that

killed 48 people. Numerous guidelines on policies for hill site development were

introduced with more stringent conditions for approval. The introduction of

Accredited Checkers in 2007 by BEM for geotechnical designs of hill site

3

development and the established of the Slope Engineering Branch in Public Works

Department (PWD) are some of the initiatives implemented to improve slope

engineering practices and mitigate the risk of landslides.

Factors that influence slope stability: (Applied Mechanics and Materials: Volumes

256-259)

i) Soil and rock strength (soil type and stratification)

ii) Discontinuities and planes of weakness

iii) Ground water and seepage

iv) External loading

v) Slope geometry

vi) Type of vegetation at slope

Most of the slope fail due to the existence of ground water and increase of pore

water pressure in ground. The control of water is the most important aspect of the

final design and construction of the slope. Because almost all slope failures are

caused or aided by water in one way of another, the control of water plays very

important role in the design and maintenance of the slope.

Horizontal drainage design in slope is a very essential in the slope to minimize the

failure of the slope. Horizontal drains are often used to lower water table elevations,

or reduce pore pressures, which increases shear strength of the soil and improve

stability.

4

1.2 Problem Statement

Every year, huge amount of money is required to do the slope rectification especially

during heavy raining season due to heavy rain fall. It was found that although the

slopes were reasonably well-designed and proper drainage was provided, the

maintenance of slope and drainage was very poor and in some cases, nonexistent.

The lack of maintenance was found to be so bad that entire slopes required costly

redesign and reconstruction. Some of the slopes had already failed, while others

were about to fail and could lead to costly damage including loss of life. This meant,

unnecessary waste of funds and exposure to needless risks to life and limb.

Various way can be done to minimize the unnecessary waste of funds and reduce the

failure of slope. Value engineering (VE) can be applied on the design in the slope.

VE analysis should be conducted as early as practicable in the planning or development

of a project, preferably before the completion of preliminary design. At a minimum, the

VE analysis is to be conducted prior to completing the final design.

Value engineering as an organized effort to analyze the functions of systems,

equipment, facilities, services, and supplies for the purpose of achieving essential

functions at the lowest life-cycle cost consistent with required performance, quality,

and safety.

Engineers have been doing this type of analysis as a matter of course in their work

since engineering was developed. It is important for optimizing expenditures of funds.

Value engineering is not a matter of reducing the scope of a project, compromising the

performance of an element, or simply substituting cheaper materials that will not

function with the required reliability.

5

1.3 Aim of Study

The main cause of occurrence of slope failure mostly due to the lack or improper

design of drainage. This is worsen during heavy rain or raining seasons. A study on

the drainage design in slope by using Value Engineering is performs to see the

feasibility of the design of horizontal drainage in slope.

1.4 Project Aims and Objectives

The application of value engineering in the drainage design in slope located in Putra

Jaya Precinct 9, Malaysia will be studied. Different combination of alternative

designs with different components in the slope will be evaluate in term of its value.

1.5 Scope of study

The horizontal drain have the ability to lower water table elevations, or reduce pore

pressures, which increases shear strength of the soil and improve stability. The

installation of horizontal drain will benefit the slope in long term. By using Value

Engineering, one of the component in slope design which is horizontal drain will be

evaluate.

1.6 Structure of Outline

The study of Value Engineering on drainage design in slope consists of five main

chapters which are the introduction, literature review, methodology, analysis and

results, and conclusion and recommendation.

Chapter 1: Introduction

The introduction chapter consists of general idea about the study which relates to

value engineering and drainage design in slope stability.

6

Chapter 2: Literature Review

This chapter describes aspect such as study on the causes of slope failure due to the

groundwater in slope and usage of horizontal drains in slope. The purpose of

literature review is to show the researched that has done and have some ideas and

limitations on what previous study that been done. However, it is not found that any

researcher has use Value Engineering to evaluate the horizontal drain in slope.

Chapter 3: Methodology

This chapter will explain on the method of how value engineering is being evaluate

on the study on drainage design in slope stability. All the details regarding the data

are presented clearly according to the method. The parameter and its detail that

needed are included in this chapter.

Chapter 4: Results, Analysis and Discussion

The method of analyze all the components in slope by using Value Engineering

method will be carry out in this chapter. The horizontal drain which is one of the

vital component in the slope will be performed by using the cost benefit analysis.

Based on the data and information that obtained, the data is analyzed and results will

be presented.

Chapter 5: Conclusion and Recommendation

This chapter discusses the conclusions based on the analysis using value engineering

and suggested the most economical selection without changing the function of the

component. Recommendations on this study in the future are also included.

7

CHAPTER 2

LITERATURE REVIEW

2.1 General Review

The drainage design that will affect the slope stability that has been done by previous

research is being studied and Value Engineering background together with its

application will be include in this chapter.

As mention from previous chapter, slope failure or landslide is a natural disaster

which occurs all around the world where the unstable slopes will slide and fail due to

the gravity pull.

Most of the slope fails because of the increase of the groundwater due to heavy or

prolonged rainfall. Ground water conditions responsible for slope failures are related

to rainfall through infiltration, soil characteristics, antecedent moisture content, and

rainfall history (Guzzetti et al., 2007). Heavy rainfall or continuous precipitation is

one of the main causes for a landslide to occur (Fuhrmann et al., 2002; Chowdhury

& Flentje, 2002; Ahrendt & Valentin Zuquette, 2003; Pedrozzi, 2004; McLeod,

2006; Guzzetti et al., 2007; Okada et al., 2007; Sivrikaya et al., 2007).

8

Pierson et al. (1992) observed that landslides in Hawaii coincided with or followed

an extremely heavy rainfall. From the research, rainfall threshold for the initiation of

landslides in central and Southern Europe done by Guzzeetti et al. (2007) shows that

rainfall will trigger slope failure. According to Sidle (2006), mountain roads have the

greatest impact on landslides per unit area on the place affected by landslide.

The groundwater’s pressure in the soil will cause the instability of a slope. The

increase of pore water pressure due to the rainwater penetrates into the soil will

decrease the shear strength of soil (Iverson, 1997; McLeod, 2006; Sivrikaya et al.,

2007). When, the shear strength of soil decrease, the slope will lost it strength to

resist the load (soil) above it. Hence, the slope will slide and fail.

2.2 Landslides Classification

There are various ways in which landslides can be classified within the field of

landslide research according to Glade et al. (2005). Landslides are normally

classified based on material types (e.g. rock, debris, earth), mechanisms of

movement (e.g. fall, topple, slide, flow, creep), degree of disruption of the displaced

mass and so forth.

In practice, it is difficult to assign a landslide to a particular class. Commonly,

landslides are complex processes, for example with rotational shear planes in the

upper part and flow structures in the lower reach.

The most commonly used landslide classifications are based on material type (e.g.

rock, debris, earth), mechanisms of movement (e.g. fall, topple, slide, flow, creep)

and degree of disruption of the displaced mass. Landslide classifications are

discussed by Hutchinson (1988), Crozier (1989), Cruden and Varnes (1996), and

9

Dikau et al. (1996). The classification of Landslides suggested by Varnes (1978) is

given in the table below:

Table 2.1: Classification of Landslides Suggested by Varnes (1978)

Type of movement

Type of material

Bedrock Engineering Soils

Predominantly coarse

Predominantly

fine

Falls Rock fall Debris fall Earth fall

Topples

Rock

topple Debris topple Earth topple

Slides

Rotational Few

units

Rock

slump Debris slump Earth slump

Translational Many

units

Rock

block slide Debris block slide

Earth block

slide

Rock slide Debris slide Earth slide

Lateral spreads Rock

spread Debris spread Earth spread

Flows

Rock flow

(deep

creep)

Debris flow Earth flow (soil

creep)

Complex and compound Combination of two or more principal types of

movements

The mechanism and severity of impact depends on the type of landslide, its impact

characteristics, and the location of elements at risk with respect to the particular

morphological components of the landslide. Schuster et al. (2002) observed that

most casualties were caused by high-velocity debris avalanches and high to medium-

velocity, highly mobile, long-run out debris flows. The impact potential or power of

a landslide is primarily a function of its mass and velocity. At the most dangerous

end of the power spectrum are rock avalanches that can attain volumes of tens of

millions of cubic meters and travel at velocities up to 60-80 m/sec (McSaveney,

2002). The range of landslide velocities is shown in Table 2.2

10

Table 2.2: Classification of Velocity of Movement According to Cruden and Varnes

(1996) and Australian Geomechanics Society (2002)

Speed

class Description

Velocity

(mm/s)

Typical

velocity Probable destructive significance

7 Extremely

fast

Disaster of major violence, buildings

destroyed by impact of displaced material,

many deaths, escape unlikely

5 x 103

5 m/sec

6 Very fast Some lives lost; velocity too great to permit

all persons to escape

5 x 101

3 m/min

5 Fast Escape evacuation possible; structures;

possessions and equipment destroyed

5 x 10-1

1.8 m/hr

4 Moderate Some temporary and insensitive structures

can be temporarily maintained

5 x 10-3

13

m/month

3 Slow

Remedial construction can be undertaken

during movement; insensitive structures can

be maintained with frequent maintenance

work if total movement is not large during a

particular acceleration phase

5 x 10-5

1.6

m/year

2 Very slow Some permanent structures undamaged by

movement

5 x 10-7

16

mm/year

1 Extremely

slow

Imperceptible without instruments,

construction possible with precautions