BEARING CAPACITY OF PARTIALLY SKIRTED FOOTINGS

ON SAND

Final Task

To fulfil the requirements of

Achieving S-1 graduate degree of Civil Engineering

Prepared by:

DANAR ARIANGGA WINDRA GAUTAMA

D 100 123 005

CIVIL ENGINEERING DEPARTMENT

ENGINEERING FACULTY

CIVIL ENGINEERING DOUBLE DEGREE

UNIVERSITAS MUHAMMADIYAH SURAKARTA

2017

iii

MOTTO

خير م الناس أنفع ه ل لناس

“Sebaik Baik Manusia Adalah Yang Paling Bermanfaat Bagi Orang Lain”

“As Good As The Most Common Man For Others”

ك م أحسنت م أحسنت م إ ن نف س ل

“Jika kalian berbuat baik, sesungguhnya kalian berbuat baik bagi diri kalian sendiri”

“If you do good, you do good for yourself”

(QS. Al-Isra:7)

”Rasulullah Shallallahualaihiwassalam bersabda,’Orang beriman itu bersikap ramah dan

tidak ada kebaikan bagi seorang yang tidak bersikap ramah. Dan sebaik-baik manusia

adalah orang yang paling bermanfaat bagi manusia”

“Rasulullah Shallallahualaihiwassalam said,’ The believer is friendly and there is no good

for a man who is not friendly. And the best man is the person most beneficial to humans”

(HR. Thabrani dan Daruquthni)

ين الله يرفع نكهم ءامنهوا الذ ين م هوا والذ هوت لم أ ه تعملهون ب ما والله درجات الع خب يره

“Allah akan meninggikan orang-orang yang beriman di antaramu dan orang-orang yang

diberi ilmupengetahuan beberapa derajat”

“Allah Almighty will exalt those who believe among you and those who are given some

degree of knowledge”

(Q.s. al-Mujadalah : 11)

iv

DEDICATION SHEET

By the say Alhamdulillah,

The author dedicates this work to :

Mr. Dr. H. Slamet Winaryo M.Si (father), Mrs. Dra. Hj. Riyani (mother),

my brother and my sister who give me guidance, love, hope, prayer and

morale or material encouragement.

Ms. Erlyn Sintya Wardani for her total support, love and endless patient.

My friends of International Majors for the joy, and the friendship.

My friends thank your for all the great moments and happiness.

Universitas Muhammadiyah Surakarta.

v

vi

PREFACE

Assalamu’alaikum Wr.Wb

Praise to Allah SWT for His grace and His mercy so the author could finish

the Final Task Report well.

ThepreparationofFinalTaskwiththetitle“BearingCapacityofPartially

SkirtedFootingsonSand”.TheFinalTaskarrangedforfulfiltherequirementsof

achieving S-1 graduate degree of Civil Engineering Department, Engineering

Faculty of Universitas Muhammadiyah Surakarta.

The Final Task can be finished with supports of several parties. Therefore

in this occasion, the author would like to say thank you to :

1. Mr. Ir. Sri Sunarjono, M.T, Ph.D as a Dean of Engineering Faculty of

Universitas Muhammadiyah Surakarta.

2. Mr. Mochamad Solikin, S.T, M.T, Ph.D as a Head Program of Civil

Engineering Major of Universitas Muhamamdiyah Surakarta.

3. Mr. Anto Budi Listyawan, S.T, M.Sc as an Acamedic Counselor and as the

first examiner.

4. Mr. Agus Susanto, S.T, M.T as an Advisor who is willingly to give the

guidance and briefing in finishing the report.

5. Mrs. Ir. Renaningsih, M.T as the second Examiner.

6. All lecturers of Civil Engineering Department who has provide knowledge

to the author in the implementation of academic activites.

7. To my parents, Mr. Dr. H. Slamet Winaryo and Mrs. Dra. Hj. Riyani for the

prayers and the blessing, support, and endless of affection

8. To my brother and sister and my entire family, thank you for the support

and love.

9. Special thanks to Ms. Erlyn Sintya Wardani for her endless love and

support.

10. To all my friends in Civil Engineering Department of Universitas

Muhammadiyah Surakarta thanks for the help.

11. ToCESA,mycivil’sfamily,keepgoingguys.

12. To all parties who cannot be mentioned one by one, thanks for the help.

viii

viii

TABLE OF CONTENTS

page

APPROVAL SHEET ..................................................................................... ii

MOTTO SHEET ............................................................................................. iii

DEDICATION SHEET .................................................................................. iv

STATEMENT OF FINAL PROJECT ............................................................. v

PREFACE ..................................................................................................... vi

TABLE OF CONTENTS ................................................................................ viii

LIST OF TABLES ......................................................................................... x

LIST OF FIGURES ........................................................................................ xi

LIST OF NOTES ........................................................................................... xii

ABSTRACT .................................................................................................. xiii

CHAPTER I. INTRODUCTION

A. Background ........................................................................................ 1

B. Problem Formulation .......................................................................... 2

C. Research Objective and Benefit .......................................................... 2

D. Limitation Problem ............................................................................. 3

E. Research Authenticity ........................................................................ 4

CHAPTER II. LITTERATURE REVIEW

A. Footing ............................................................................................... 6

B. Skirt Footings ..................................................................................... 6

C. Footings on Sand ................................................................................ 7

D. Suction Effect of Skirt Footings .......................................................... 8

E. Bearing Capacity of Skirt Foundations ............................................... 8

F. Similiar Research Review ................................................................... 9

CHAPTER III. BASIC THEORY

A. Bearing Capacity ................................................................................ 11

B. Ultimate Bearing Capacity .................................................................. 13

C. Settlement .......................................................................................... 14

D. Skirt (Vertical Plate) .......................................................................... 15

ix

E. Water Content and Compaction .......................................................... 15

CHAPTER IV. RESEARCH METHOD

A. General ............................................................................................... 16

B. Research Location .............................................................................. 16

C. Research Material ............................................................................... 16

D. Research Equipment ........................................................................... 16

E. Research Step ..................................................................................... 21

CHAPTER V. ANALYSIS AND DISCUSSION

A. General Test Result ............................................................................ 24

B. Ultimate Bearing Capacity .................................................................. 27

C. Settlement .......................................................................................... 30

D. The Differences with Previous Research ............................................. 36

CHAPTER VI. CONCLUSION AND RECOMENDATION

A. Conclusion ......................................................................................... 40

B. Recomendation ................................................................................... 41

REFFERENCES ............................................................................................. 42

APPENDIX .................................................................................................... 43

x

LIST OF TABLES

page

Table I.1 ThedifferencesbetweenthisstudyandAmr.ZELWakil’s ........... 4

Table V.1 Ultimate bearing capacity on different partilally skirt length ......... 27

Table V.2. Ultimate bearing capacity on the different diamater ..................... 28

Table V.3 Ultimate bearing capacity increment ............................................. 29

Table V.4 Settlement alteration on 2.00 kN load ........................................... 30

Table V.5 Load alteration at 10 mm of settlement. ........................................ 33

Table V.6. Ultimate bearing capacity on different diameter ........................... 36

Table V.7. Ultimate bearing capacity on different skirt length ....................... 37

Table V.8. The settlement on P = 2 kN,mm ................................................... 38

xi

LIST OF FIGURES

page

Figure III.1 Types of bearing capacity failure .............................................. 13

Figure IV.1 Partially skirted circular footings model ................................... 17

Figure IV.2 The Partially Skirted Footings .................................................. 18

Figure IV.3 The 9 partially skirted footings and 3 un-skirted footings ......... 18

Figure IV.4. Sketch setup of testing procedures ........................................... 19

Figure IV.5 The setup of testing procedures ................................................ 20

Figure IV.3 Flow Chart of Research ............................................................ 23

Figure V.1 Load-settlement relationship for footings 75 mm diameter ........ 24

Figure V.2 Load-settlement relationship for footings 100 mm diameter ...... 25

Figure V.3 Load-settlement relationship for footings 150 mm diameter ...... 26

Figure V.4 Ultimate bearing capacity, L/D ratio relationship, different L .... 27

Figure V.5 Ultimate bearing capacity, L/D ratio relationship,

different diamater ........................................................................................ 28

Figure V.6. Settlement analysis on footings diameter 75 mm ...................... 31

Figure V.7. Settlement analysis on footings diameter 100 mm .................... 31

Figure V.8. Settlement analysis on footings diameter 150 mm .................... 32

Figure V.9 Load analysis at 10 mm settlement on footings diamater

75 mm ........................................................................................................ 33

Figure V.10. Load analysis on 10 mm settlement of footings diamater

100 mm....................................................................................................... 34

Figure V.11 Load analysis on 10 mm settlement of footings diameter

150 mm....................................................................................................... 34

Figure V.11. Ultimate bearing capacity on different diameter ...................... 37

Figure V.12. Ultimate bearing capacity on different skirt length .................. 38

Figure V.13. The settlement on P = 2 kN ................................................... 39

xii

LIST OF NOTES

D = footings diameter (mm)

L = skirt length (mm)

Ts = thickness of skirt (mm)

Tf = thickness of footings (mm)

L/D = the ratio between skirt length (L) and footings diameter (D)

Dr = relative density

c = apparent cohesion

ɸ = angle of internal friction

Fɣ = skirt factor

Dfs = depth to foundation base below ground level (m)

B’ = total foundation width with skirts(B+2Bs) (m)

Bs = skirt thickness (m)

ɣ = unit weight of soil (kN/m3)

Nɣ, Nq, Nc = factor of bearing capacity, based on the internal friction

angle (φ) from the soil under the footing base.

Ds = depth to the lower edge of the skirt below the foundation

base(m)

qu = ultimate bearing capacity (kN/m2)

c2 = cohesion of soil under the footing (kN/m2)

Df = depth of footing (m)

B = width or diameter of footing (m)

ɣ1 = unit weight of soil above the footing base (kN/m3)

ɣ2 = unit weight of soil under the footing base (kN/m3)

Pmax = maximum load (kN)

A = area of footings (m2)

S = total of settlement (mm)

Si = immeditate settlement (mm)

Sc = primary consolidation (mm)

Ss = secondary consolidation (mm)

xiii

BEARING CAPACITY OF PARTIALLY SKIRTED

FOOTINGS ON SAND

Abstrak

Daya dukung tanah memiliki faktor yang sangat penting dalam menentukan tiper

pondasi. Penting untuk menemukan cara untuk meningkatkan dari kedua sektor

dasar baik itu pada pondasi atau pada tanah. Dengan menambahkan skirt sebagian

(penahan vertikal sebagian) mengelilingi permukaan pondasi dapat digunakan

sebagai salah satu alternatif dalam meningkatkan daya dukung pondasi. Penelitian

ini menggunakan duabelas model laboratorium skirt sebagian dengan berbagai

macam ukuran diameter dan panjang skirt sebagian, dengan pemadatan yang sama

pada tanah pasir sebagai media. Dari hasil percoban didapatkan skirt sebagian

meningkatkan daya dukung pondasi hingga 2,97 kali dari pondasi tanpa skirt. Skirt

sebagian juga mengurangi penurunan yang terjadi hingga 82% pada nilai beban

yang sama yaitu 2kN. Skirt sebagian yang memiliki skirt terpanjang menghasilkan

pengurangan penurunan yang terbaik.

Kata Kunci: skirt sebagian, pondasi melingkar, daya dukung, penurunan,

pondasi, pasir.

Abstract

Soil bearing capacity has the most important role to determine the type of

foundation. It is important to find an effort of improvement in both sectors of

fundamental area either it is on foundation or in soil itself. By adding the partially

skirt (partially vertical plate) surroundings under the footings surface can be used

as an alternative of improvement the bearing capacity of foundation. This research

is performing twelve laboratory models of partially skirted footings with different

diameter and partially skrit length, on the sand soil as a media with same

compaction method. From the laboratory test which has been done, it was found

that the partially skirts improve the bearing capacity of foundation up to 2.97 times

than the unskirted foundation. The partially skirt also reduce the settlement up to

82 % in average in the same value of 2 kN load. The partially skirt with the longest

skirt has the best result in reducing the settlement.

Keywords: partially skirt, circular footing, bearing capacity, settlement,

foundation, sand.