View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by UTHM Institutional Repository i A CRITICAL PERFORMANCE STUDY OF INNOVATIVE LIGHTWEIGHT FILL TO MITIGATE SETTLEMENT OF EMBANKMENT CONSTRUCTED ON PEAT SOIL TUAN NOOR HASANAH BINTI TUAN ISMAIL A thesis submitted in fulfillment of the requirements for the award of the Doctoral of Philosophy Faculty of Civil and Environmental Engineering Universiti Tun Hussein Onn Malaysia March 2017 iii Specially Dedicated to My beloved husband and family Thanks for all the love and support Sincerely, Tuan Noor Hasanah binti Tuan Ismail iv ACKNOWLEDGEMENT In the name of Allah, the Most Gracious and the Most Merciful Syukur Alhamdulillah and all thanks are due to Allah for gave me strength and ability to complete my research successfully. First and foremost, I would like to express my deepest gratitude to my project supervisor, Prof. Dr. Devapriya Chitral Wijeyesekera for his supervision and guidance, invaluable assistance and his constant confidence in me. Without his continued guidance and support, this thesis would not have been a success. Forever I appreciate his patience and availability for any help whenever needed despite his heavy workload. I would like to express my sincere appreciation to Prof. Dato’ Dr. Ismail Hj. Bakar as my co supervisor for their helpful suggestions, assistance, and encouragement. His absolute support is greatly appreciated. I also gratefully acknowledge all the academic staffs and support staffs especially Mr As-Shar bin Kasalan and Mdm. Salina binti Sani for assisting and give the guidance to me during conducting the laboratory and field works. I am also very thankful to all my colleagues and other researchers I have met for their help, encouragement, motivation and friendship on my research work. Financial support from MTUN-COE grant and MyPhD scholarship are also gratefully acknowledged Heartfelt acknowledgements are expressed to my beloved husband and parents for their sacrifices, support and encouragement. Without them, I may never have overcome this long journey in my studies. Not forgetting my siblings for their friendship and support during the difficult times of my study. May Allah reward all of you. Thank you… v ABSTRACT Infrastructure construction now demands the development on soft ground such as peat. Discomfort of road users such as bumpy road need to be addressed with the use of appropriate lightweight and stiff backfill materials. Alternative lightweight fills used in current highway construction is critically reviewed in this research prior to the conceptual development of a stiff lightweight mat (Geocomposite Cellular Mat, GCM). The GCM concept is somewhat similar to the EPS concept by virtue of the mat form. However, the EPS is lighter than GCM, but the GCM is much stronger, stiffer, more porous and permeable. The performance of the GCM on hemic peat ground at the test site in Parit Nipah, Johor was compared with that from conventional backfill (sand fill). The typical geotechnical properties of Parit Nipah peat were high in organic content (85.3 %), high in moisture content (> 600 %) and low in undrained shear strength (< 15 kPa). The consolidation characteristics of Parit Nipah peat was obtained from both laboratory and field tests using Terzaghi’s, and hyperbolic methods. The settlement predicted by hyperbolic method gave a better agreement with the field data. The field tests were environmentally monitored and innovative field instrumentation for the settlement monitoring was specially designed for this research. The research effectively demonstrates potential for the use of GCM to mitigate settlement of highway embankment built on peat ground. The field observation showed that the maximum settlements were reduced up to 84 % with the adoption of GCM fills. Furthermore, 70 % differential settlement was reduced with GCM fill compared with sand fill. GCM fills not only reduces excessive settlement but also reduces the differential settlement. However, they also effectively accelerate the consolidation settlement within the sub-grade through the ease of dissipation of the excess pore water pressure through the open-porous cellular structure of the GCM fills. vi ABSTRAK Pembinaan infrastruktur di atas tanah lembut contohnya tanah gambut kini mendapat permintaan yang tinggi. Namun yang demikian, pembinaan jalan raya diatas tanah gambut memberi ketidakselesaan kepada pengguna jalan raya disebabkan oleh jalan yang beralun dan ini perlu ditangani dengan pendekatan yang sesuai seperti penggunaan bahan tambak yang ringan dan kuat. Melalui penyelidikan ini, kajian secara kritikal terhadap bahan alternatif tambak ringan yang digunakan dalam pembinaan jalan raya masa kini telah dilakukan sebelum pembangunan konseptual bahan tambak berbentuk tikar yang ringan dan keras (Geocomposite Celular Mat, GCM). GCM mempunyai konsep yang hampir sama dengan EPS iaitu berbentuk tikar. Namun yang demikian, EPS adalah lebih ringan berbanding GCM, tetapi GCM lebih kuat, keras, poros dan telap jika dibandingkan dengan EPS. Hasil ujikaji terhadap prestasi GCM ke atas tanah gambut hemik yang dilakukan di tapak ujikaji terletak di Parit Nipah, Johor dibandingkan dengan tambak konvensional berbentuk pasir. Ciri geoteknikal tanah gambut di Parit Nipah yang tipikal mempunyai kandungan organik yang tinggi (85.3%), kandungan kelembapan yang tinggi (> 600 %) dan kekuatan ricih yang rendah (< 15 kPa). Ciri-ciri pengukuhan tanah gambut ini diperoleh melalui ujikaji makmal dan lapangan dengan menggunakan kaedah Terzaghi dan hiperbolik. Kaedah hiperbolik menunjukkan ramalan pemendapan lapangan yang lebih baik berbanding dengan kaedah lain. Pemantauan terhadap persekitaran kawasan lapangan telah dilakukan dan penggunaan peralatan tapak telah direka khas dalam kajian ini untuk memantau pemendapan. Hasil kajian menunjukkan potensi penggunaan GCM bagi mengurangkan pemendapan penambakan jalan raya yang dibina diatas tanah gambut adalah sangat efektif. Kajian lapangan menunjukkan penggurangan sehingga 84% terhadap pemendapan maksimum berjaya dicapai dengan menggunakan GCM. Selain itu, perbezaan pemendapan juga berjaya dikurangkan sebanyak 70 % dengan penggunaan GCM. GCM bukan saja dapat mengurangkan jumlah dan perbezaan pemendapan, ianya juga mampu mempercepatkan pemendapan subgred secara efektif dengan memudahkan penyerapan lebihan tekanan air liang melalui struktur sel liang terbuka GCM. vii TABLE OF CONTENTS TITLE i DECLARATION ii DEDICATION iii ACKNOWLEDGMENT iv ABSTRACT v TABLE OF CONTENTS vii LIST OF TABLES xv LIST OF FIGURES xix LIST OF SYMBOLS AND ABBREVIATIONS xxviii LIST OF APPENDICES xxxiv CHAPTER 1 - INTRODUCTION 1.1 Preamble 1 1.2 Problem identification 3 1.3 Research hypothesis 5 1.4 Research aim and objectives 5 1.4.1 Aim of the research 5 1.4.2 Objectives of the research 5 1.5 Scope (boundary) of research 6 1.6 Research programme 8 1.7 Thesis outline 9 CHAPTER 2 – LITERATURE REVIEW 2.1 Introduction 10 2.2 Settlement induced failure of highways and infrastructures on soft 10 soil viii 2.3 Problematic soils in Malaysia 13 2.3.1 Definition of peat soil 13 2.3.2 Peatland in Malaysia 15 2.3.2.1 Peat morphology 17 2.3.2.2 Structural arrangement of peat soil 18 2.3.2.3 Classification of peat soil (engineering) 19 2.3.2.4 Characteristic properties of peat soils 21 2.3.2.5 Critical review of characteristic properties of peat 24 soils at Parit Nipah, Johor 2.4 Ground improvement methods 25 2.4.1 Alternative construction technologies using lightweight fill 29 materials particularly for road construction 2.4.1.1 Expanded polystyrene (EPS) geofoam 30 2.4.1.2 Shredded tires and tire bale fills 32 2.4.1.3 Foamed concrete (blocks/panel) 34 2.4.1.4 Bamboo grid frame 35 2.4.1.5 Other lightweight fill materials (mixed or added to 36 the soils) 2.4.2 Critical design properties of feasible lightweight fill blocks 39 used in embankment construction 2.4.3 Review of past literature on road embankments constructed 42 using lightweight fill material 2.5 Plastic (synthetic and semi-synthetic polymer) as an alternative 48 lightweight construction materials 2.5.1 Why recycled plastics? 50 2.5.2 Engineering and thermal properties of plastic 53 2.5.2.1 Properties of virgin plastic 53 2.5.2.2 Critical review of mechanical properties of 55 recycled plastic blends 2.5.3 Use of plastic in engineering field 58 2.6 Contributory advantages from cellular structure 61 2.6.1 Characteristic properties of cellular solids 65 2.6.2 Engineering applications of cellular structure 67 ix 2.7 Field monitoring instrumentation 70 2.7.1 Survey method for measuring vertical movement 72 2.7.2 Comparisons of field instrumentation 78 2.7.3 Appropriate field instrumentation for embankment over soft 79 ground 2.8 Consolidation settlement of soils 83 2.8.1 Consolidation model for peat soils 84 2.8.1.1 Cα/Cc concept (1977) 84 2.8.1.2 Rheological model for peat soil (1961) 86 2.8.1.3 Summary of rheological model 90 2.8.2 Consolidation behaviour of peat 90 2.8.3 One-dimensional consolidation test 94 2.8.4 Settlement prediction based on one-dimensional 96 consolidation test 2.8.5 Applicability of Terzaghi’s theory to predict settlement over 102 peat 2.8.6 Comparative overview of classical One-dimensional (1D), 104 three-dimensional (3D) and large strain consolidation theories 2.8.7 Settlement prediction during construction period 110 2.9 Alternative methods of settlement analysis 112 2.9.1 Hyperbolic method 112 2.9.2 Asaoka method 116 2.10 Guideline and standard for road embankment construction