Determination of the horizontal (radial) coefficient of consolidation by from oedometer test with horizontal drainage using incremental loading method

ABSTRACT The radial (horizontal) coefficient of consolidation (c r) is a key parameter which impacts the total consolidation of the PVD-improved grounds In practice, the c r value can be interpreted from field tests and laboratory tests A radial consolidation test (RCT) might be conducted using incremental loading (IL) method with either a central drain (CD) or a peripheral drain (PD) The key goals of the research are: (1) to design and manufacture a multi-directional flow consolidometer (VCT, RCT-PD, RCT-CD) using incremental loading method; (2) to make a comparative study on the c r values obtained from the RCTIL using a PD and a CD; (3) to make a comparative study on the cr values derived from RCT-based method and CPTu-based method A desk study is carried out to secure the following: (1) a literature review on equipment used for the test and existing methods used to evaluate the cr value; (2) graphical design of a multi-directional flow consolidation cell Sampling and CPTu dissipation tests are carried out at sites Besides the basic physical lab tests, the RCT IL with a CD and a PD will be performed using the designed consolidation cell under same condition test Overall, the ratio of kr/kv is approximately equal the ratio of cr/cv The cr, PD & cr, CD are double to triple higher than cv The cr, CD values are about 1.5 times larger than figures of cr, PD Finally, the cr values determined from CPTu-based method are doubled higher than cr values obtained from RCT-based method The reliability of the new device is confirmed Moreover, the results of c r values in the case of both PD and CD obtained by interpreting with traditional method like square root time method is more reliable than non-graphical method The limitation of the study is that the amount of data is still limited so it is still not enough to fully confirm the reliability of the multidirectional flow consolidation cell In the future, the author intends to perform more consolidation and permeability tests to ensure that the new designated consolidation can be applied in routine performance i ACKNOWLEDGEMENTS I would like to express my sincere appreciation for the lecturers of Master of Infrastructure Engineering Program for their help during my undergraduate at Vietnam Japan University (VJU) My thesis supervisor Dr Nguyen Tien Dung for his enthusiasm, patience, advice and constant source of ideas Dr Dung has always been available to reply to my questions His support in professional matters has been priceless Special gratitude is given to LAS- XD 442 lab and the staff at Institute of Foundation and Underground, Golden Earth Inc for their kindly support for performing the laboratory work And finally, I want to spent my thank to my parents and friends for their unflinching support in the tough time Their support, spoken or unspoken, has helped me complete my master thesis ii TABLE OF CONTENTS ABSTRACT i ACKNOWLEDGEMENTS ii TABLE OF CONTENTS iii LIST OF FIGURES vii LIST OF TABLES ix LIST OF ABBREVIATIONS xi CHAPTER 1: INTRODUCTION 1.1 Background 1.2 Consolidation 1.2.1 Settlement with Prefabricated Vertical Drains (PVD) .3 1.3 Problem statement 1.4 Objectives and scope of present study CHAPTER 2: LITERATURE REVIEW 2.1 Fundamentals of One Dimensional Consolidation 2.1.1 Consolidation Theory with Vertical Drainage 10 2.1.2 Consolidation Theory with Horizontal Drainage 11 2.2 Consolidation Tests in Laboratory 15 2.2.1 Vertical oedometer consolidation test 15 iii 2.2.2Horizontal Consolidatio 2.3Determination of Coefficient of Consolidation 2.3.1Analysis of Time-Comp 2.3.2Graphical Method 2.3.2Non-graphical Method 2.4Falling Head Permeability Test 2.5The piezocone penetration test (CPTu) 2.5.1Introduction 2.5.2Pore-water Dissipation 2.5.3Coefficient of Consolid CHAPTER 3: METHODOLOGY 3.1Introduction 3.2Radial Consolidation Test 3.2.1Design of the equipme 3.2.2Manufacture of the equ 3.2.3Testing procedure 3.2.4Analysis procedure 3.3Vertical consolidation test 3.3.1Testing procedure 3.3.2Analysis of Time-Comp 3.4Permeability test 3.4.1Equipment of permeab 3.4.2Testing procedure iv 3.4.3 3.5 Analysis procedure CPTu dissipation test 3.5.1 Equipment 3.5.2 Testing procedure 3.5.3 Analysis procedure 3.6 Results verification and comparison CHAPTER 4: TEST RESULTS & DISCUSSIONS 4.1 Introduction 4.2 Summary of test performed 4.3 Comparison of cr,PD and cv 4.3.1 Square root time meth 4.3.2 Non-graphical method 4.3.3 Inflection point method 4.4 Comparison cr,CD and cv 4.4.1 Square root time meth 4.4.2 Non-graphical method 4.4.3 Inflection point method 4.5 Comparison cr,PD and cr, CD 4.5.1 Square root time meth 4.5.2 Non-graphical method 4.5.3 Inflection point method 4.6 4.6.1 Horizontal coefficient of consolidation (cr) from CPT Estimate cr value from m v 4.6.2 Estimate cr value from non-standard dissipation curves 59 4.7 Test verification 61 4.8 Comparison cr,PD, cr,CD vs cr, CPTu 62 CHAPTER 5: CONCLUSIONS & RECOMMENDATIONS 65 REFERENCES 68 vi LIST OF FIGURES Figure 1.1: Soil phase diagram (Das, 2008) Figure 1.2: Primary consolidation (Das, 2008) Figure 1.3: Typical oedometer settlement (Das, 2008) Figure 1.4: Settlement damage Figure 1.5: Drainage with and without drains Figure 2.1: Mechanism of consolidation Figure 2.2: Uv versus Tv relationship (Head, 1986) Figure 2.3: Schematic diagram of an RCT with central drain and peripheral drain Figure 2.4: (a) Scheme of arrangement of the consolidation test in the triaxial apparatus, with drainage towards the cylindrical surface; (b) Cylindrical element of the sample Figure 2.5: Distribution of pore pressures within the soil sample related to r and t Figure 2.6: Schematic of oedometer test (Head, 1986) Figure 2.7: Schematic of the apparatus used for conducting radial consolidation test Figure 2.8: Rowe cell test under equal strain loading, horizontal outward drainage Figure 2.9: Shapes of consolidation curve gained from oedometer test Figure 2.10: Theoretical curve linkage square-root time factor to degree of consolidation for vertical drainage (Taylor, 1942) Figure 2.11: Consolidation curve relating square-root time factor to for drainage radially outwards to periphery with equal strain loading (Head, 1986) Figure 2.12: (a) Theoretical Ur-log Tr curve for n = 5; (b) (dUr/d log Tr)-log Tr plot showing the inflection point (Sridhar and Robinson, 2011) Figure 2.13: Falling-head permeability test (Das, 2017) Figure 2.14: Principal sketch of horizontal and vertical trimming of samples from determining vertical and horizontal coefficient of permeability Figure 2.15: Overview of the cone penetration test per ASTM D 5778 procedures Figure 2.16: Strain path solution for CPTu1 dissipation tests (The and Houlsby, 1991) Figure 2.17: Strain path solution for CPTu2 dissipation tests (The and Houlsby, 1991) Figure 2.18: "Non-standard" dissipation curve ( Chai et al., 2012) Figure 3.1: Equipment for radial consolidation test with peripheral drainage vii Figure 3.2: Flow chart of the study 34 Figure 3.3: Equipment for radial consolidation test with central drainage 35 Figure 3.4: Manufacture of the equipment for radial consolidation with PD 36 Figure 3.5: Manufacture of equipment for radial consolidation test with CD 36 Figure 3.6: Radial consolidation with peripheral drain and central drain setup 37 Figure 3.7: Equipment of falling head permeability test 39 Figure 3.8: Falling head permeability test setup 40 Figure 3.9: The typical and complete electrical CPT system 42 Figure 4.1: Comparison of cv and cr,PD obtained from square root time method at 400 kPa & 800 kPa 46 Figure 4.2: Comparison of cv and cr,PD obtained from non-graphical method at 400 kPa & 800 kPa 47 Figure 4.3: Comparison of cv and cr,PD obtained from inflection point method at 400 kPa & 800 kPa 48 Figure 4.4: Comparison of cv and cr,CD obtained from square root time method at 400 kPa & 800 kPa 49 Figure 4.5: Comparison of cv and cr,CD obtained from non-graphical method at 400 kPa & 800 kPa 50 Figure 4.6: Comparison of cv and cr,CD obtained from inflection point method at 400 kPa & 800 kPa 51 Figure 4.7: Comparison of cr,PD and cr,CD obtained from square root time method at 400 kPa & 800 kPa 52 Figure 4.8: Comparison of cr,PD and cr,CD obtained from non-graphical method at 400 kPa & 800 kPa 53 Figure 4.9: Comparison of cr,PD and cr,CD obtained from inflection point method at 400 kPa & 800 kPa 54 Figure 4.10: Strain path solution for monotonic dissipation tests at 11 & 17m 57 Figure 4.11: Strain path solution for monotonic dissipation tests at 18.5 & 20.5m 58 Figure 4.12: Dilatory dissipation curve at 8.5m 59 Figure 4.13: Dilatory dissipation curve at 9.5 & 11.3 m 60 Figure 4.14: Results of test verification which compares the ratios between kr/kv with cr/cv 61 Figure 4.15: Comparison between cr,CPTu with cr,PD obtained from square root time method at 400 kPa 64 viii Figure 5.1 Comparison between results obtained from square root time, non-graphical and inflection point method at 400 kPa 67 Figure 5.2: Comparison between results obtained from square root time, non-graphical and inflection point method at 800 kPa 67 ix Figure 4.12: Dilatory dissipation curve at 8.5m 59 water pressure u (kPa0 Dissipation test 02 - 9.51 m pore t50 10 100 1000 10000 100000 Excess Time t (s) 10 Dissipation test 04 - 11.3 m 300 t50 250 200 150 100 10 100 1000 10000 100000 Figure 4.13: Dilatory dissipation curve at 9.5 & 11.3 m 50 60 4.7 Test verification Figure 4.12 illustrates the results of test verification which compares the ratios between kr/kv with cr/cv 3.8 cr,PD / cv 3.7 3.6 3.5 3.4 3.3 3.2 3.1 3.0 2.9 2.8 2.7 2.6 2.5 2.5 kr / kv 3.5 cr,PD / cv 3.4 3.3 3.2 3.1 3.0 2.5 2.4 2.4 kr / kv Figure 4.14: Results of test verification which compares the ratios between kr/kv with cr/cv 61 Coefficient of hydraulic conductivity can be measured base on the permeability test through equation 3.1 The coefficient of permeability is shown in Table 4.4 Table 4.5: Coefficient of permeability obtained from permeability tests Depth 8.0 – 9.0 m 9.0 - 10.0 m 16.5 - 17.3 m 4.8 Comparison cr,PD, cr,CD vs cr, CPTu The value of cr,PD , cr,CD obtained by using square root time method at 400 kPa and 800 kPa and cr derived from monotonic and dilatory dissipation curves are listed in table 4.4 Figure 4.12 presents the comparison between c r,PD obtained from square root time method at 400 kPa and cr estimated from dissipation curves 62 Table 4.6: Comparison cr,PD and cr,CD obtained by square root time method with cr,CPTu Depth (m) 8.0 – 9.0 9.0 – 10.0 10.5 – 11.5 16.5 – 17.3 18.0 – 18.7 19.5 – 20.5 63 0.035 0.030 r, PD c (cm2/s) 0.025 0.020 0.015 0.010 0.005 0.000 0.000 cr, CPTu (cm /s) Figure 4.15: Comparison between cr,CPTu with cr,PD obtained from square root time method at 400 kPa 64 CHAPTER 5: CONCLUSIONS & RECOMMENDATIONS For the accuracy of multi- directional flow consolidation cell is designed to conduct oedometer test with both peripheral drain and central drain is verified with the test results from permeability test The ratio of k r/kv is around which is satisfy the ranged of fine-grained soil In contrast, the fraction of c r/cv is also ranged from to with difference depth of soil samples These ratios is somewhat connect with each other and plot around 1:1 axis Hence the multidirectional consolidation cell could be response to the oedometer test in both case of peripheral drain and central drain The data obtained from multi-directional consolidation cell to estimate three important consolidation parameters of soil including vertical coefficient of consolidation and radial coefficient of consolidation with PD and CD at n = 2.21 Based on the results derived from consolidation curves, when applying the square root time method, the cr,PD value estimated is nearly double to the cv value at same loading condition of 400 kPa and 800 kPa Meanwhile, the c r,CD value is around three times to the c v value This indicates that the horizontal coefficient of consolidations obtained from multi-directional consolidation cell with both outward drainage and inward drainage are not identical as theory and it ranged from to 1.5 when conducted tests with new devices In other hand, when applying non-graphical method and inflection point method to analyze the time- settlement curves monitored from conventional oedometer test the results also fluctuate The horizontal coefficient of consolidation calculated from consolidation test with PD larger than approximately three times with vertical coefficient of consolidation In the same case, the c r,CD values is much larger and when compares with vertical coefficient of consolidation the ratios is also vicinity with Moreover, the results of radial coefficient of consolidation in the case of both 65 peripheral drain and central drain obtained by interpreting with these methods is somewhat the largely difference The ratios of cr,PD and cr,CD is ranged from 1.5 to which is far from the 1:1 ratio as the theory has approved Hence the interpreting of horizontal coefficient of consolidation with both inward and outward drainage by applying traditional method like square root time method is more reliable than non-graphical method Figure 5.1 and 5.2 illustrates the difference between the results obtained when depicting with three difference analytical methods The results of radial coefficient of consolidation estimated from CPTu dissipation tests is much higher than these value calculated when subjected by both 400 kPa and 800 kPa The ratios of these values are changed around 1:2 line In the future, the multi-directional flow consolidation cell should be conducted more tests at another place to verify its reliable before employing in routine performance The limitation of the study is that the amount of data is still limited due to the rush time so it is still not enough to fully confirm the reliability of the multi-directional flow consolidation cell In the future, the author intends to perform more consolidation and permeability tests to ensure that the new designated consolidation can be applied in routine performance 66 0.022 0.020 0.018 0.016 0.014 r, CD c (cm2/s) 0.012 0.010 0.008 0.006 0.004 0.002 0.000 0.000 Figure 5.1 Comparison between results obtained from square root time, non-graphical and inflection point method at 400 kPa 0.020 0.018 0.016 0.014 0.012 r, CD c 0.010 0.008 0.006 800 kPa from square root time, non-graphical and inflection point method at 800 kPa Figure 5.2: C o m p a r i s o n b e t w e e n r e s u l t s o b t a i n e d 67 REFERENCES ASTM D2435 / D2435M - 11 (2011) Standard Test Methods for One-Dimensional Consolidation Properties of Soils Using Incremental Loading ASTM International, West Conshohocken https://doi.org/10.1520/D2435_D2435M-11 Barron, R A., Lane, K S., Keene, P., & Kjellman, W (2002) Consolidation of finegrained soils by drain wells In Geotechnical Special Publication (Vol 113) Chai, J., Sheng, D., Carter, J P., & Zhu, H (2013) Corrigendum to “Coefficient of consolidation from non-standard piezocone dissipation curves” [Comput Geotech 41 (2012) 13–22] Computers and Geotechnics https://doi.org/10.1016/j.compgeo.2013.03.002 Chung, S., Lee, N., & Kim, S.-R (2009) Hyperbolic Method for Prediction of Prefabricated Vertical Drains Performance In Journal of Geotechnical and Geoenvironmental Engineering (Vol 135) https://doi.org/10.1061/ (ASCE)GT.1943-5606.0000042 Das, B M., & Sobhan, K (2008) Principle of Geotechnical Engineering In Global Engineering Fahey, M., & Carter, J P (2008) A finite element study of the pressuremeter test in sand using a nonlinear elastic plastic model: Reply Canadian Geotechnical Journal https://doi.org/10.1139/t94-096 Head, K H (1994) Manual of soil laboratory testing Vol Permeability, shear strength and compressibility tests In Geoderma https://doi.org/10.1016/0016-7061(95)90001-2 Jamiolkowski, M., Ladd, C C., Germaine, J T., & Lancellotta, R (1985) New developments in field and laboratory testing of soils , SAN FRANCISCO, 12-16 AUGUST 1985 11th Int Conf on Soil Mechanics and Foundation Engineering 68 Krage, C P., DeJong, J T., & Schnaid, F (2014) Estimation of the Coefficient of Consolidation from Incomplete Cone Penetration Test Dissipation Tests Journal of Geotechnical and Geoenvironmental Engineering https://doi.org/10.1061/(asce)gt.1943-5606.0001218 Mayne, P.W (2007) NEHRP-Cone Penetration Testing a Synthesis of Highway Practice In Nchrp Mayne, Paul W (2001) Stress-strain-strength-flow parameters from enhanced in-situ tests Proceedings of the International Conference on In-Situ Measurement, Bali, Indonesia, May 21-24, 2001 Robinson, R G., & Allam, M M (1998) Analysis of consolidation data by a non-graphical matching method Geotechnical Testing Journal https://doi.org/10.1520/GTJ10752J Sridhar, G., & Robinson, R (2011) Determination of radial coefficient of consolidation using log t method International Journal of Geotechnical Engineering https://doi.org/10.3328/ijge.2011.05.04.373-381 Sridharan, A., Prakash, K., & Asha, S R (1996) Consolidation behavior of clayey soils under radial drainage Geotechnical Testing Journal Teh, C I (1991) An analytical study of the cone penetration test in clay G&technique Vesic, A S (1973) On penetration resistance and bearing capacity of piles in sand 8th International Conference on Soil Mechanics and Foundation Engineering 69 ... routine test For a given soil under the same magnitude of applied pressure, the RCTIL of both drainage types should result in the same value of c r, but the problems associated with the test using. .. and scope of present study The key goals of the research are to investigate the effectiveness of the RCT IL using a PD compared with the test using a CD and to propose a comprehensive method to... multi-directional flow consolidation cell that should be able to perform the RCTIL using either a CD or a PD - To highlight the advantages of the test using a PD over the test using a CD in testing procedures