Luận văn Phân tích một số yếu tố ảnh hưởng đến cường độ nén nở hông của cọc xi măng đất tại công trình đường liên cảng Cái Mép – Thị Vải và đánh giá hiệu quả của phụ gia muội silic

 BÁO CÁO TỐT NGHIỆP Đề tài Phân tích số yếu tố ảnh hưởng đến cường độ nén nở hông cọc xi măng đất công trình đường liên cảng Cái Mép – Thị Vải đánh giá hiệu phụ gia muội silic ĐẠI HỌC QUỐC GIA TP.HCM CỘNG HOÀ XÃ HỘI CHỦ NGHĨA VIỆT NAM TRƯỜNG ĐẠI HỌC BÁCH KHOA Độc lập – Tự – Hạnh phúc TP Hồ Chí Minh, ngày … tháng … năm …… NHIỆM VỤ LUẬN VĂN TỐT NGHIỆP Khoa: Kỹ thuật Địa Chất Dầu Khí Bộ môn: Địa Kỹ Thuật Họ tên: NGUYỄN VĂN CƯỜNG MSSV: 30600264 Chuyên nghành: ĐỊA KỸ THUẬT Lớp: DC06KT Đề tài luận văn: FACTORS AFFECT ON UNCONFINED COMPRESSIVE STRENGTH OF SOIL CEMENT COLUMN IN THI VAI – CAI MEP INTER-PORT ROAD AND ASSESSING EFFECT OF SILICA FUME ADMIXTURE Nhiệm vụ luận văn: - Tiến hành trộn, bảo dưỡng, nén mẫu xi măng đất phòng thí nghiệm - Tổng hợp, thống kê, phân tích kết thí nghiệm, thiết lập biểu đồ thể mối tương quan, đánh giá kết thí nghiệm - Tiến hành so sánh khác biệt cường độ cọc đất xi măng thực tế so với mẫu trộn phòng thí nghiệm - Trình bày, luận giải yếu tố ảnh hưởng đến cường độ cọc xi măng đất Ngày giao nhiệm vụ luận văn: 01/08/2010 Ngày hoàn thành luận văn: 30/12/2010 Cán hướng dẫn: ThS Nguyễn Thanh Nhàn, TS Nguyễn Minh Trung CÁN BỘ HƯỚNG DẪN CÁN BỘ HƯỚNG DẪN (Ký ghi rõ họ tên) (Ký ghi rõ họ tên) Nội dung yêu cầu luận văn thông qua môn Ngày … tháng … năm 20… CHỦ NHIỆM BỘ MÔN (Ký ghi rõ họ tên) ACKNOWLEDGEMENT And there come a day when I graduated thesis, still there be joyful to get graduation The helps and continuous supports from teachers, friends, and family whom I am most grateful make me mature Without you, all of you, I don’t know who I am today I would like to thank each of you individually by word, but also I in my heart I would like to express my deepest gratitude to my supervisor, MSc Nguyen Thanh Nhan and Dr Nguyen Minh Trung, with a spirit of enterprise for his strong support and whole-hearted guidance, encouragement and advice in this study Especially, MSc Nguyen Thanh Nhan, I don’t forget the time when he spent with me in numerous discussions in this research His rich knowledge in the geotechnical engineering has also been most helpful in guiding this study I have learned a lot from his thorough and insightful review of this research and his dedication to producing high quality In additional, he made me many opportunities to practice Then I could directly practice almost theory which I had studied He made considerable contribution to my project During the time I study, I received helping from all teachers in my department, especially Dr Phan Thi San Ha She helped me to understand clay minerals, pozzolanic reaction and many problems in geotechnics My friends, my brothers helped me to my graduation thesis enthusiastically I am grateful to all of you Doing this project helped me improve my knowledge of major English very much With me, English is very important when I work in the future Although I tried my best to finish my graduation thesis in English language, I think it still had many mistakes I wish I will receive many contributions of you Best regards Nguyen Van Cuong i TÓM TẮT Đề tài LVTN: “Phân tích số yếu tố ảnh hưởng đến cường độ nén nở hông cọc xi măng đất công trình đường liên cảng Cái Mép – Thị Vải đánh giá hiệu phụ gia muội silic.” Tuyến đường liên cảng Cái Mép – Thị Vải nối liền hệ thống cảng khu công nghiệp chạy dọc sông Cái Mép - Thị Vải với tổng vốn đầu tư 6300 tỉ đồng Hiện thi công đoạn số (từ km + 199 – km + 612) Vị trí công trình nằm khu vực đất yếu thuộc trầm trích sông biển hỗn hợp có tính chất phức tạp Do để đảm bảo khả khai thác tuyến đường tải trọng cao đòi hỏi phải có giải pháp móng hợp lý kinh tế Với ưu điểm công tác xử lý đất yếu, công nghệ cột xi măng đất xem giải pháp tối ưu cần phải xem xét ứng dụng rộng rãi Để góp phần thực điều này, luận văn tác giả tập trung vào nghiên cứu vấn đề sau: - Tìm hiểu sở lý thuyết phương pháp cọc xi măng đất - Tiến hành trộn mẫu phòng để phân tích số yếu tố ảnh hưởng đến cường độ nén nở hông, đánh giá hiệu phụ gia muội silic đưa hàm lượng tối ưu - Nghiên cứu ảnh hưởng môi trường xung quanh: • Chịu ảnh hưởng nước (điều kiện nước ngầm) • Sự thay đổi hàm lượng muối đất • Môi trường đất tự nhiên xung quanh cọc - So sánh khác biệt cường độ cọc đất xi măng thực tế so với mẫu trộn phòng thí nghiệm ii ABSTRACT The graduation thesis: “Factors affect on unconfined compressive strength of soil cement column in Thi Vai – Cai Mep inter-port road and assessing effect of silica fume admixture.” The Cai Mep-Thi Vai inter-port road system connects to the ports system and industrial zones along the Cai Mep - Thi Vai River, total of initial investment equals 6300 billions VND The component project No.3 (Km 7+199 to Km 9+612) is being executed at present The construction is located on weak soil foundation of near shore marine – alluvial deposit which has complex properties Therefore, to ensure the effectively using of the super-weight construction needs to have a reasonable and economical geological solution With the specific advantage in weak soil foundation treatment, the soil cement column is considered a most optimal solution needs to research and apply To contribute to execute above matter, in this research (composition), the author has researched and analyzed some matter as follows: - To understand theory of soil cement column - Preparing, mixing, testing specimens in laboratory in order to analysis factors affecting on unconfined compressive strength of soil cement samples, assessing effect of silica fume admixture and outputting optimum mixture ratio - Researching effect of curing environment: • The effect of water to strength of soil cement columns • The effect of salt content in water to strength of soil cement columns • The effect of natural soil around columns - Research the correlation of unconfined compressive strength between laboratory mixed specimens and core samples of soil cement columns iii TABLE OF CONTENTS ACKNOWLEDGEMENT i TÓM TẮT ii ABSTRACT iii TABLE OF CONTENTS iv LIST OF FIGURES viii LIST OF TABLES xii INTRODUCTION 1 General .1 Purpose and scope of research Methodology of study Scientific significance of research Practical significant of research .5 Innovation of the research Limitations of research CHAPTER 1: LITERATURE REVIEW 1.1 History and application of soil cement column .6 1.1.1 History .7 1.1.2 Application 10 1.1.3 Typical arrangement patterns of soil cement columns 15 1.2 Overview of method of constructions soil cement columns 17 1.2.1 Dry Jet Mixing (DJM) 17 1.2.2 Wet Jet Mixing (WJM) 18 1.3 Investigation on reaction in soil cement columns 19 1.3.1 Composition of Portland Cement 19 iv 1.3.2 Basic mechanisms of soil cement stabilization .21 1.4 Silica fume admixture 31 1.4.1 Definition .31 1.4.2 Silica fume properties and reaction chemical 31 1.5 Factors affecting on unconfined compressive strength of soil cement columns 33 1.5.1 Effects of type, characteristics and Conditions of Soil to be improved 34 1.5.2 Effect of cement content 36 1.5.3 Effect of water/cement ratio 38 1.5.4 Effect of mixing condition .40 1.5.5 Curing condition 44 1.6 The correlation between strength and strain 48 1.7 Summary 52 CHAPTER 2: THE TESTING METHODS IN LABORATORY 53 2.1 Soil Characterization 53 2.1.1 Moisture Content (ASTM D 2216-98 and ASTM D 4643-00) .53 2.1.2 Particle Size Distribution (ASTM D 422-63) 53 2.1.3 Atterberg Limits (ASTM D 4318-00) 53 2.1.4 Classification (ASTM D 2478-00) 54 2.1.5 Organic Content (ASTM D 2974-00) 54 2.1.6 Specific Gravity (ASTM D 854-00) 54 2.1.7 pH (ASTM D 4972-01) 54 2.1.8 Sulfate Content (AASHTO T290-95) 54 2.1.9 Mineralogical Analysis 55 2.2 Laboratory of Research Variables, Defining related parameter and volume of research 55 2.2.1 Laboratory of Research Variables 55 2.2.2 Specimen Notation 56 v 2.2.3 Defining related parameter 56 2.3 Preparing for Laboratory research .57 2.3.1 Location of soil sample use to test and method of sample taking 57 2.3.2 Necessary equipments 57 2.4 Preparing, Curing specimens (JGS 0821-2000) 59 2.4.1 Preparing specimens 59 2.4.2 Curing specimens 60 2.4.3 Unconfined compressive strength test (ASTM D 2166-00) 62 2.5 Summary 64 CHAPTER THE FACTORS AFFECT ON UNCONFINED COMPRESSIVE STRENGTH OF SOIL CEMENT COLUMNS 64 3.1 General introduction of Cai Mep - Thi Vai inter-port route project 64 3.1.1 Soil Characterization .66 3.2 Analysis and valuation of test results in Laboratory 70 3.2.1 The correlation between unconfined compressive strength and cement content .70 3.2.2 Effect of water/cement ratio to unconfined compressive strength 73 3.2.3 Effect of Silica fume/cement ratio to unconfined compressive strength when cement content equals 220 kg/m3, water/cement ratio equals 0.7 .76 3.2.4 Effect of curing time to unconfined compressive strength 79 3.2.5 Effect of curing environment to unconfined compressive strength .82 3.3 Analysis and valuation of test results core sampling from soil cement columns 85 3.3.1 Affecting of cement content 85 3.3.2 The correlation between UCS and Water/ cement ratio 86 3.3.3 Correlation between stress and strain 88 3.4 Comparison between strength of specimens is mixed in LAB and FIELD 88 vi CONCLUSIONS AND RECOMMENDATIONS 95 AREAS FOR FUTURE RESEARCH 97 REFERENCES 98 APPENDIXES 101 vii “Chapter 3: The factors affect on unconfined compressive strength of soil cement columns” Unconfined Compressive Strength (kPa) 1600.0 "Field - A - 220 - 0.7 - 0% 1400.0 "Lab - 220 - 0.7 - 0% Field - B - 220 - 0.7 - 0% 1200.0 1000.0 800.0 600.0 400.0 200.0 0.0 14 21 28 35 Curing time (days) Cement content equals 220 kg/m3; water/cement ratio equals 0.7 Unconfined Compressive Strength (kPa) 1800.0 Field - A - 240 - 0.7 - 0% 1600.0 Lab - 240 - 0.7 - 0% 1400.0 Field - B - 240 - 0.7 - 0% 1200.0 1000.0 800.0 600.0 400.0 200.0 0.0 14 21 Curing time (days) 28 35 Cement content equals 240 kg/m3; water/cement ratio equals 0.7 89 “Chapter 3: The factors affect on unconfined compressive strength of soil cement columns” Unconfined Compressive Strength (kPa) 1400.0 Field - A - 260 - 0.7 - 0% 1200.0 Lab - 260 - 0.7 - 0% Field - B - 260 - 0.7 - 0% 1000.0 800.0 600.0 400.0 200.0 0.0 14 21 28 35 Curing time (days) Cement content equals 260 kg/m3; water/cement ratio equals 0.7 Unconfined Compressive Strength (kPa) 1400.0 Field - A - 220 - 0.8 - 0% 1200.0 Lab - 220 - 0.8 - 0% Field - B - 220 - 0.8 - 0% 1000.0 800.0 600.0 400.0 200.0 0.0 14 21 28 35 Curing time (days) Cement content equals 220 kg/m3; water/cement ratio equals 0.8 90 “Chapter 3: The factors affect on unconfined compressive strength of soil cement columns” 1800.0 Unconfined Compressive Strength (kPa) Field - A - 240 - 0.8 - 0% 1600.0 Lab - 240 - 0.8 - 0% 1400.0 Field - B - 240 - 0.8 - 0% 1200.0 1000.0 800.0 600.0 400.0 200.0 0.0 14 21 28 35 Curing time (days) Cement content equals 240 kg/m3; water/cement ratio equals 0.8 Unconfined Compressive Strength (kPa) 1400.0 Field - A - 260 - 0.8 - 0% 1200.0 Lab - 260 - 0.8 - 0% Field - B - 260 - 0.8 - 0% 1000.0 800.0 600.0 400.0 200.0 0.0 14 21 28 35 Curing time (days) Cement content equals 260 kg/m3; water/cement ratio equals 0.8 Figure 3.32: Comparison between strength of specimens mix in LAB and FIELD 91 “Chapter 3: The factors affect on unconfined compressive strength of soil cement columns” Laboratory mixing is often more complete than field mixing, and the strength of laboratory mixed specimens can be greater than the strength of field mixed materials at the same mixture proportions In research, the strength of field mixing by contractor A may vary from 100 to 115 percent of the strength of laboratory mixed specimens The strength of field mixingby contractor B may vary from 42 to 67 percent of the strength of laboratory mixed specimens Thence, we can realize that ability of contractors affects on confined compressive strength of soil cement column very much The difference in test result between contractor A and contractor B may be caused some reasons as following: • Mixing machines: - Contractor A: They made in Japan (highly evaluation in the World) and some machine made in China, they was improved quality after contractor A constructed Can tho airport project - Contractor B: They made in China • Type of mixing paddle, paddle angel 92 “Chapter 3: The factors affect on unconfined compressive strength of soil cement columns” Figure 3.33: Mixing paddle of contractor A • Weights and measures systems was intended for controlling weight of binder, water/cement ratio, mixing energy, penetration speed, mixing cycle,… (Figure 3.34) 93 “Chapter 3: The factors affect on unconfined compressive strength of soil cement columns” Figure 3.34: Operators Cabin For High Performance Quality Control (Photographic image from research of Ulli Wiedemann, Germany) According to EuroSoilStab (2002), the strength of field mixed materials may be from 20 to 50 percent of the strength of laboratory mixed specimens According to Coastal Development Institute of Technology (CDIT),(2002), the strength of field mixed materials may be from 20 to 100 percent of the strength of laboratory mixed specimens The percentage depends on the type and operation of the mixing equipment, as well as the soil type and mixing conditions 94 “Chapter 3: The factors affect on unconfined compressive strength of soil cement columns” CONCLUSIONS AND RECOMMENDATIONS  Conclusion From the research, author took out the conclusions following: - Optimum mixture ratio: The optimum cement content in laboratory mixed specimens and field mixed even equals 240 kg/m3 (in compare with wet density) The optimum water/cement ratio in laboratory mixed specimens equals 0.8 but it equals 0.7 in field mixed - Affect of curing environment Curing environment affect negligibly strength of soil cement columns The highest strength of specimens is cured in soil environment, lower in city water, NaCl 2.5 % and then NaCl 5% -Evaluating the effect of silica fume admixture: The optimum silica fume admixture equals 1% (in compare with weight of cement content) This result was showed on research time (60 days) We need to research on long term to evaluate effect of silica Because we have to notice pozzolanic reaction between Ca(OH)2 and clay material, especially in research area, type of clay is montmorillonite which is most active clay - Correlation between the strength of field mixed materials and laboratory mixed specimens: Strength of soil cement columns is depended on contraction very much In research, the strength of field mixed by contractor A may be 100 to 115 percent of the strength of laboratory mixed specimens The strength of field mixed by contractor B may be 36 to 67 percent of the strength of laboratory mixed specimens 95 “Chapter 3: The factors affect on unconfined compressive strength of soil cement columns”  Recommendation The highest strength of soil cement columns is at cement content equals 240 kg/m3 (qu = 700 - 15000kPa) But designer need to notice quality assurance in order to avoid wasting money because design strength of soil cement columns only equals 300kPa The preparing and mixing specimens is needed to conform to standard and have to carefully Because this process affects much on strength of soil cement samples Especially, noticing process of surface working samples Value of modulus (E) will decrease when surface working sample is prepared without care To continue research in order to assess effect of silica fume admixture and clear affecting of other factors 96 “Chapter 3: The factors affect on unconfined compressive strength of soil cement columns” AREAS FOR FUTURE RESEARCH Admixture is used for soil cement column To continue study silica fume on long term in order to evaluate effect of this admixture for soil cement columns Field Quality Control/Quality Assurance: Much work is need to develop and optimize quality control and quality assurance for soil cement column construction in the field Such procedure could include observations of column construction, laboratory test of specimens formed from grab samples, laboratory testing on core samples, direct penetration tests, reserve penetration (pull-out) test, pressuremeter tests, column load tests, and geophysical tests Modeling the behavior of soil cement columns under runway by finite element analysis (FEM) It is very useful for designer They can identify efficiency of subgrade soil when it improved by CDM, so we can correct design of construction Thenceforth, they are reliable economical effective 97 “Chapter 3: The factors affect on unconfined compressive strength of soil cement columns” REFERENCES Vietnamese Documents [1] Đậu Văn Ngọ (2009) “Các nhân tố ảnh hưởng đến cường độ xi măng đất” Tạp chí phát triển khoa học công nghệ Vol 12, 06-11- 2009 [2] Lý Huỳnh Anh Lý (2007) “Nghiên cứu ảnh hưởng môi trường xung quanh đến cường độ cọc đấ t xi măng” Luận văn tốt nghiệp cao học Trường Đại học Bách Khoa Thành Phố Hồ Chí Minh [3] Nguyễn Thành Đạt (2010) “N English Documents [1] Ahnberg, H., Ljungkratnz, C., 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www.raitoinc.com http://www.schnabel com http://www.raito.co.jp http://www.hatien1.com.vn http://www.eng.warwick.ac.uk 102 “Chapter 3: The factors affect on unconfined compressive strength of soil cement columns” APPENDIXES 103