Engineering FINAL YEAR PROJECT FACULTY OF ENGINEERING KNS 4222 EFFECT OF FINE CONTENT ON SHEAR STRENGTH OF SAND. Name : Kho Joo Tiong

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1 Engineering FINAL YEAR PROJECT FACULTY OF ENGINEERING KNS 4222 EFFECT OF FINE CONTENT ON SHEAR STRENGTH OF SAND Name : Kho Joo Tiong Matrics No. : 6670 Bachelor of Engineering with Honour (Civil engineering) 2004

2 UNIVERSITI MALAYSIA SARAWAK BORANG PENYERAHAN STATUS TESIS Judul: Effect of Fine Content on Shear Strength of Sand Sesi Pengajian: Saya KHO JOO TIONG (HURUF BESAR) mengaku membenarkan tesis * ini disimpan di Pusat Khidmat Maklumat Akademik, Universiti Malaysia Sarawak dengan syarat-syarat kegunaan seperti berikut: 1. Tesis adalah hamilik Universiti Malaysia Sarawak. 2. Pusat Khidmat Maklumat Akademik, Universiti Malaysia Sarawak dibenarkan membuat salinan untuk tujuan pengajian sahaja. 3. Membuat pengdigitan untuk membangunkan Pengkalan Data Kandungan Tempatan. 4. Pusat Khidmat maklumat Akademik, Universiti Malaysia Sarawak dibenarkan membuat salinan tesis ini sebagai bahan pertukaran antara institusi pengajian tinggi. 5. ** Sila tandakan ( ) di kotak berkenaan SULIT (Mengandungi maklumat yang berdarjah keselamatan atau kepentingan Malaysia seperti yang termaktub di dalam AKTA RAHSIA RASMI 1972) TERHAD (Mengandungi maklumat TERHAD yang telah ditentukan oleh organisasi/badan di mana penyelidikan dijalankan). TIDAK TERHAD Disahkan oleh: (TANDATANGAN PENULIS) ALAMAT TETAP: Lot 9080, Taman Matang Jaya, Phase 20, Jalan Matang Jaya, 93050,Kuching Sarawak Tarikh: (TANDATANGAN PENYELIA) Nama Penyelia Tarikh: CATATAN * Tesis dimaksudkan sebagai tesis bagi Ijazah Doktor Falsafah, Sarjana dan Sarjana Muda ** Jika tesis ini SULIT atau TERHAD, sila lampirkan surat daripada pihak berkuasa/organisasi berkenaan dengan menyatakan sekali sebab dan tempoh tesis ini perlu dikelaskan sebagai SULIT dan TERHAD.

3 EFFECT OF FINE CONTENT ON SHEAR STRENGTH OF SAND KHO JOO TIONG This project is submitted in partial of fulfilment of the requirements for the degree of Bachelor of Engineering with Honours (Civil Engineering) Faculty of Engineering UNIVERSITI MALAYSIA SARAWAK 2005 i

4 The following Final Year Project Report: Title : EFFECT OF FINE CONTENT ON SHEAR STRENGTH OF SAND Name : KHO JOO TIONG Matrix Number : 6670 has been read and approved by : DR. PRABIR KUMAR KOLAY Date Project Supervisor ii

5 Dedicated to my family and beloved one iii

6 ACKNOWLEDGEMENTS First and foremost, the author would like to thank God, who reserves the highest of praise for His entire blessing. Without His love, guidance and comfort, the author will have a hard time for the difficulties encountered during the preparation of this final year project. A special thanks also goes to the Project supervisor, Prof. Zoynul Abedin and Dr. Prabir Kumar Kolay for his high vision, guidance, support and precious knowledge throughout the project work. Thanks for shepherding with diligence and patience. The author is very grateful to his family, especially Madam Chung Le Ling, who always give her full supports and love. Thank you for provide financial and emotional supports. Your advice and guidance will be always bear in mind. The author also take this opportunity to thank the laboratory assistants of Civil Engineering Program, Faculty of Engineering, Universiti Malaysia Sarawak for their guidance and assistance in carrying out the laboratory works during the project duration. To the beloved one, the author is fortunate to share the precious moment with you in his life. Thank you for the moral support given and hope all of this is worth for both of us. Last but not least, not forgetting to the author s friends Ong, Chai, Wong, Chong, Adrian, Dorothy, Ling and Oon who involved directly and indirectly in iv

7 helping for the completion of this project. This project work has been a work of knowledge and future for all of us. v

8 ABSTRACT The present study aims the effect of fine content (passing 75μm sieve) on the shear strength characteristics of sand. To achieve this goal, three sand samples collected from different location of Sarawak, namely Batu Kitang, Sibu and Damai, were mixed with different percentages (i.e. 0%, 5%, 10%, 20% and 30%) of fine content. Direct shear test has been conducted to determine the shear strength parameters of these mixtures. For Damai sand, the fine content is less than 1%, hence effect of fine content on shear strength properties could not be studied. The results reveal that with the increase of fine content, the angle of internal friction, φ, values decreases for all the mixed sand samples. With the 30% increase of fine content, the angle of internal friction, φ, decreases by 35.18% and 38.61% for Batu Kitang Sand (DS-5) and Sibu Sand (DS-10), respectively. On the other hand, the cohesion value, c increases from kn/m 2 to kn/m 2 and from kn/m 2 to kn/m 2, were observed with the increase of fine content by 30%, for DS-5 and DS-10, respectively. vi

9 ABSTRAK Kajian ini adalah berkaitan dengan pengkajian tentang kesan kandungan fine content (melepasi 0.075mm ayak) dengan ciri-ciri kekuatan ricih pasir. Untuk mencapai tujuan ini, tiga sampel pasir yang diperolehi daripada kawasan-kawasan berlainan di Sarawak seperti Batu Kitang, Sibu dan Damai dicampur dalam peratusan yang berlainan (contohnya, 0%, 5%, 10%, 20% and 30%) dengan fine content. Ujian Kotak Ricih telah dijalankan untuk mengenalpasti kekuatan ricih campuran tersebut. Untuk pasir Damai, jumlah fine content yang diperolehi adalah kurang daripada 1%, maka kesan kandungan fine content ke atas ciri-ciri kekuatan ricih pasir tidak dapat dikaji. Keputusan menunjukkan kekuatan ricih campuran tersebut akan semakin berkurangan dengan peningkatan kandungan fine content. Dengan penambahan sebanyak 30% fine content, nilai geseran antara zarah-zarah pasir, φ berkurang sebanyak 35.18% dan 38.61% bagi Pasir Batu Kitang (DS-5) dan Pasir Sibu (DS-10) masing-masing. Dalam kes lain, nilai kejeleketan, c bertambah dari kn/m 2 ke kn/m 2 dan dari kn/m 2 ke kn/m 2 untuk penambahan fine content sebanyak 30% bagi DS-5 dan DS-10 masing-masing. vii

10 TABLE OF CONTENTS CONTENTS APPROVAL LETTER APPROVAL SHEET TITLE PAGE ACKNOWLEDGEMENTS ABSTRACT ABSTRAK TABLE OF CONTENTS LIST OF TABLES LIST OF FIGURES LIST OF NOMENCLATURES PAGE i iii iv v viii ix xi CHAPTER 1 INTRODUCTION 1.1 General Statement of the problem Objective of the present study Organization of the thesis 5 CHAPTER 2 LITERATURE REVIEW 2.1 General Shear strength of soil and shear strength theories Mohr-Coulomb Theory Hvorslev Theory 9 viii

11 2.3 Shear strength of sand Effect of density on shear strength of sand Shear strength of compacted sands and gravels Strength of gypsum sandy silts Concluding remarks 20 CHAPTER 3 MATERIALS, TEST PROGRAMME AND PROCEDURE 3.1 General Test material Test programme Test procedure Separation of materials Determination of specific gravity Determination of shear strength 25 CHAPTER 4 RESULTS AND DISCUSSION 4.1 General Determination of grain size distribution Determination of specific gravity Determination of shear strength For Batu Kitang Sand For Sibu Sand 38 ix

12 4.4.3 For Damai Sand 40 CHAPTER 5 CONCLUSION AND RECOMMENDATION 5.1 Conclusion Recommendation 44 REFERENCES 45 APPENDIX A APPENDIX B APPENDIX C Method of calculations Experimental data Experimental graph x

13 LIST OF TABLES TABLE PAGE Table 3.1 Designation for the parent and fine samples collected 22 from different location. Table 3.2 Test Programme 23 Table 4.1 Physical (index) properties of original sand samples 30 Table 4.2 Physical (index) properties of parent sample mixed 31 with different percentages of fine content Table 4.3 Specific gravity of Batu Kitang, Sibu & Damai sand 33 and their mixtures with different percentages of fine content xi

14 LIST OF FIGURES TABLE PAGE Fig. 2.1 Mohr-Coulomb theory- Failure envelopes; 9 (a) Coulomb s envelope; (b) Mohr sgeneralized failure envelope (after, Venkatramaiah, 1995). Fig. 2.2 Coulomb s envelope; (a) sand soil ; and (b) 9 clay soil (after, Venkatramaiah, 1995). Fig. 2.3 Stress-strain-volume change data for dense 13 sand ( After Lee and Seed, 1967) Fig. 2.4 Stress-Strain-volume change data for loose 14 sand (After Lee and Seed,1967) Fig. 2.5 Relative density vs. friction angle for 16 cohesionless soils(after Fang, 1991) Fig. 2.6 Angle of internal friction vs. void ratio 17 (After Zolkov and Wiseman, 1965) Fig. 4.1 Particle size distribution graph for Batu 27 Kitang sand Fig. 4.2 Particle size distribution graph for Sibu sand 28 Fig. 4.3 Particle size distribution graph for Damai 29 sand Fig. 4.4 Shear Stress versus Percent Strain for Test 35 xii

15 No.DS-1 Fig. 4.5 Shear Stress versus Percent Strain for Test 36 No.DS-3 Fig. 4.6 Shear stress versus Normal stress for Batu 37 Kitang sand Fig. 4.7 Shear stress versus Strain for Test No.DS-6 38 Fig. 4.8 Shear stress versus Strain for Test No.DS-8 39 Fig. 4.9 Shear stress versus Normal stress for Sibu 39 sand Fig Shear stress versus Strain for Test No.DS Fig Shear stress versus Normal stress for 41 Damai sand xiii

16 LIST OF NOMENCLATURES φ angle of internal friction % percent c g kn g/cm 2 kn/m 2 m 2 mm μm s σ c e φ e e cohesion gram kilo newton gram per cubic centimetre kilo newton per cubic meter cubic meter milimeter micrometer shear stress normal stress effective cohesion effective friction angle equivalent consolidation pressure K 0 D R q c cohesion factor degree relative density cone resistance σ ff magnitude of the effective normal stress on the failure plane at xiv

17 failure φ s peak secant friction angle at σ ff p a reference stress, assumed equal to 98.1kPa φ o secant angle of friction at σ ff = 267kPa α β G s C u C z Coeff angle which describes the curvature of the failure envelope. degree of salt leaching specific gravity uniformity coefficient curvature coefficient coefficient xv

18 CHAPTER 1 INTRODUCTION 1.1 General Shear strength of a soil is perhaps the most important of its engineering properties. This is because all stability analysis in the field of geotechnical engineering, whether they relate to foundations, slopes of cuts or earth dams, earthretaining structures etc. Soil fills involve a basic knowledge of this engineering property of soil. Shearing strength of soil is the most difficult to comprehend in view of the multitude of factors known to affect it. A lot of maturity and skill may be required on the part of the engineer in interpreting the results of the laboratory tests for application to the conditions in the field. Moreover, in many occasion the collection of soil sample and laboratory tests may involve significant cost as compared to the volume of project. Geotechnical engineers have been addressing 1

19 these problems evolving simple field tests and correlating the results to shear strength of soil. It is a well-established fact that resistance due to interlocking, frictional resistance and adhesion (cohesion) between the soil particles are the principal sources in deriving the shear strength of a soil. Granular soil or sands may derive their strength from the first two sources, while cohesive soils or clays may derive their shear strength from the second and third sources. Highly plastic clays, however, may exhibit the third source alone for their shearing strength (Venkatramaiah, 1995). Most natural soil deposits and in some instances the artificial fill contain partly cohesive and partly granular soils. As such, they may inherit the strength due to the interplay of all the three contributors, like interlocking, friction and adhesion, of shear strength of soils. In other words, the strength of most of the soils is the functions of the complex combinations of the properties of soil grains of varying sizes or soil separates. Thus the matrix or the structural arrangement of the soil mass is significant in evaluating its shear strength properties. It is expected that the fine content in a coarse soil mass will change the soil matrix thus affecting the strength parameters. At lower fine contents, the dry coarse grained soil can exhibit its usual dense or loose structures, as because the in between voids of coarse grains can be filled up by fines only, not affecting the structure significantly. However, in case of larger amount of fine content the whole matrix of the soil mass may change thus affecting the strength parameters. 2

20 A significant volume of research work has been done on the various aspects of the properties of coarse-grained soils. However, the study on the effect of fine content on the coarse-grained soil is very limited. In practice, the uses of coarsegrained soils are enormous. The obvious reason may be its reliability as a good foundation soils in most of the cases. However, the undisturbed sampling and determination of shear strength of sandy soils are not always simple. The exploration cost is the other important factors for a construction project. As such, the simple insitu tests are always desirable to the engineers in order to estimate the strength properties of soils. Thus the present study was aimed at investigating the feasibility of using simple tests like determination of fine content to correlate the shear strength properties at certain density. 1.2 Statement of the Problem The effect of fine content on the properties of soil can be studied considering both in micro and macro structures of soil mass. The micro level includes the study of soil structures and fabrics using X-ray refractions and by other microscopic methods. Whereas, the macro level study emphasizes mainly the performance study. Keeping these views in mind, the present study is concentrating at the investigating of some physical and strength properties of sandy soil. Sand samples from several selected locations have been collected and fractions were separated to remix them in desired proportions to prepare sand samples having various proportions of fine contents. The 3

21 strength of the sand samples has been determined by using standard laboratory tests. The grain size distribution of the insitu (i.e., original sample) and prepared samples has also been done. The aim of the study is thus to quantify the fine content that can be accepted as the most important factor contributing to compressibility and shear strength of soils. The practical use of the findings may be used in any sand fill project by performing simple test like field density and fine content instead of more complicated and expensive laboratory tests. 1.3 Objectives of the present study The present study was aimed at investigating some selected physical and engineering properties of reconstituted sand samples having varying fine contents. Laboratory tests have been conducted in order to fulfill the following objectives. (i) To investigate the effects of fine contents on the shear strength of sand having similar density. (ii) To investigate the effect of soil fineness (fineness modulus as used in material science) on shear strength of soils. (iii) To review the available related literature in order to have an in depth view of the subject. 4

22 1.4 Organization of the thesis The present study has been carried under the curricula of two courses KNS 4223 and KNS 4256 in semester 1 and semester 2 respectively. This final outcome of this investigation (both KNS 4223 & KNS 4256) has been presented in a volume of five chapters. First chapter is essentially an introduction to the topic and the intended work. The second chapter includes the review of related literatures. Chapter three covers test programme, procedure and testing materials. Chapter four comprises of the experimental results and discussion. To summaries the work, chapter five presents the conclusion of the study and suggests the recommendations for future research. 5

23 CHAPTER 2 LITERATURE REVIEW 2.1 General The investigation is taken up to the study of the effect of fine content (sample passing 75 m) on the shear strength of sandy soils. In the following articles, the available literature related to the present study is briefly described. 2.2 Shear Strength of Soil and Shear Strength Theories The shear strength of a soil mass is the internal resistance per unit area that the soil mass can offer to resist failure and sliding along any inside plane (Das, 2002). It always refers to the resistance along a plane that passes between or along particle 6

24 surfaces (but not through the particle). The mineral composition of soil particles produce materials that have relatively high resistance to compressive and shear forces, and that rarely are fractured or sheared when a soil mass shears. A plane of resistance passing between or along particle surfaces is weaker than a plane of resistance through the solid particles (McCarthy, 2002). Thus, the failure plane as described for soil shear is an undulated surface rather than a true plane. As such, the soil shear plane may be visualized as a failure band having a finite thickness rather than a conventional plane surface. Thus, the shear strength and the failure phenomenon of soil are difficult to comprehend in view of the multitude factors known to affect this failure phenomenon. The shear strength of the soil may be attributed to three basic components: (i) resistance due to interlocking of the particles; (ii) adhesion between soil particles called cohesion; and (iii) frictional resistance between the individual soil grains, which may be either of the sliding or rolling frictions or the both. First two sources are mainly responsible for the shear strength of granular soils; second and third for the cohesive soils. It is neither easy nor practical to clearly distinguish the effects of these components on the shear strength of the soil, because these components in turn are influenced by many factors like; (i) heterogeneous nature of soil that typify most soil masses; (ii) the water table location and moisture contents; (iii) the drainage facility involving pore water pressure; (iv) the type and nature of construction; (v) stress history; (vi) structural disturbance of soil; (vii) chemical action; and (viii) environmental conditions. Therefore, the shear strength of a soil cannot be interpreted 7