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D. T. Bergado
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BEHAVIOR OF STIFFENED DEEP CEMENT MIXING PILE IN LABORATORY P. Jamsawang; D. T. Bergado; A. Bhandari; P. Voottipruex
Lowland Technology International Vol 11 No 1, June (2009)
Publisher : International Association of Lowland Technology

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The low strength and stiffness of Deep Cement Mixing (DCM) pile causes unexpected failure that has been mitigated with the introduction of stiffened deep cement mixing (SDCM) pile. The SDCM is a new type of DCM pile reinforced by concrete core pile. In this paper, the interface behavior of SDCM pile and its strength have been studied by various laboratory tests. The cement content was varied from 10 to 20% by dry weight of clay and mixed at the water content corresponding to its liquid limit to obtain optimum strengths. The interface friction between the core concrete pile and the cement-admixed clay was studied by means of the direct shear tests and Ko interface shear tests. The 15% cement content yielded optimum interface shear strength. The CIU triaxial compression test of model SDCM pile revealed that the concrete core pile length should be more than 75% of the DCM pile length in order to have significant improvement.
COMPARISON ON THE PERFORMANCE OF PREFABRICATED VERTICAL DRAIN (PVD) PRELOADING COMBINED WITH AND WITHOUT VACUUM AND HEAT J. Saowapakpiboon; D. T. Bergado; S. Artidteang
Lowland Technology International Vol 13 No 1, June (2011)
Publisher : International Association of Lowland Technology

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This paper focus on performance of prefabricated vertical drain (PVD) preloading combined with and without vacuum and heat to accelerate the consolidation of soft Bangkok clay. The laboratory tests were conducted using reconstituted specimens in large scale consolidometers combined with and without vacuum and heat. The flow parameters were back calculated in terms of the horizontal coefficient of consolidation (Ch) and the ratio between the horizontal permeability in undisturbed zone (kh) to the horizontal permeability in smear zone (ks) or (kh/ks) based on Hansbo (1979) method. The back-calculation analysis results show that the combination of vacuum pressure and heat can increase the horizontal coefficient of consolidation, Ch of 126.42% and decrease of kh/ks of 63.33%. Furthermore, vacuum can increase higher rate of consolidation temperature can decrease viscosity of pore water by reducing the drainage retardation effects in the smear zone around the PVD which resulted in faster rate of consolidation and higher magnitude of settlement.
INVESTIGATION OF TENSILE AND SOIL-GEOTEXTILE INTERFACE STRENGTH OF KENAF WOVEN LIMITED LIFE GEOTEXTILES (LLGS) S. Artidteang; D. T. Bergado; T. Tanchaisawat; J. Saowapakpiboon
Lowland Technology International Vol 14 No 2, Dec (2012)
Publisher : International Association of Lowland Technology

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Most geotextiles are made from polypropylene or polyester polymers formed into woven and nonwoven fabric. Recently, new type of geotextile called Limited life Geotextiles (LLGs) made of natural fibers are utilized. Natural fibers are renewable fibers that can be sustainable into woven geotextiles for various geotechnical engineering applications. Geotextiles have been widely used to improve short term stability of embankments on soft clay by two functions: tensile reinforcement and as a drainage element. The paper presents the results of experimental investigation from the suitable pattern of woven Kenaf LLGs for soil reinforcement. Three patterns of weaving Kenaf LLGs were obtained, namely: plain, knot-plain, and hexagonal patterns. Tensile strength tests were conducted in warp and weft directions to select the most appropriate pattern for soil reinforcement application. The plain pattern of woven Kenaf LLGs is the most appropriate pattern due to its high tensile strength. Moreover, large scale direct shear tests were carried out to find the interface strength of Kenaf woven LLGs with sand backfill material as well as the sand backfill materials under different normal confining pressures of 40, 80, and 120 kPa. The important variables for LLGs reinforcement structure design and analysis were investigated. Furthermore, pullout tests were performed using normal confining pressures of 20, 40 and 60 kPa which cover the range of possible applied confining pressures in the field applications. Slippage failure occurred below the normal confining pressure of 40 kPa and tensile failure occurred at higher normal confining pressures.
DISCUSSION ON “GEOTECHNICAL HAZARDS IN BANGKOK – PRESENT & FUTURE”, BY S. SHIBUYA, S. B. TAMRAKAR AND W. MANAKUL, LOWLAND TECHNOLOGY INTERNATIONAL, 5(1), 95-104 A. S. Balasubramaniam; N. Phienwej; D. T. Bergado; Y. N. Oh
Lowland Technology International Vol 6 No 1, June (2004)
Publisher : International Association of Lowland Technology

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The writers read with great interest the contribution on “Geotechnical Hazard in Bangkok – Present Future”. The writers had a long time interest in the subsidence of Bangkok since 1973 (see Piancharoen and Chuamthaisong, 1976; Piancharoen and Isarangula, 1974; Rammarong, 1974) or so.
3D FEM investigation on bending failure mechanism of column inclusion under embankment load S. Shrestha; J.-C. Chai; D. T. Bergado; T. Hino; Y. Kamo
Lowland Technology International Vol 17 No 3, Dec (2015)
Publisher : International Association of Lowland Technology

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Bending failure mechanism of column inclusions in soft clay deposit under embankment loading has been investigated by three dimensional (3D) finite element analyses. Firstly the effectiveness of the numerical procedure has been verified by comparing the simulated and the measured results of a centrifuge model test reported in the literature in terms of lateral displacement, settlement, and the bending moment in the column. Then the effects of the size of the column improved area from the toe toward the center of the embankment, stiffness of the column, the length of the column on the maximum bending moment in the column have been investigated numerically. The numerical results indicate that increase the size of the improved area, reduced the bending moment in the upper part (near ground surface) of the column; increase the stiffness of the column increased the maximum bending moment; and the maximum bending moment occurred at the end of the column in the case of an end bearing column, and in the upper part of the column for a floating column. The numerical results also indicate that when the whole area under the embankment is improved by end bearing columns with an area improvement ratio of 28 % and tensile strength of the column of 100 kN/m2, the embankment load can be applied with a factor of safety of about 2 for bending failure of the columns is about 13 times of the initial undrained shear strength of the soft deposit.
Effect of Polymer and Portland Cement on Strengthen Crushed Rock for Pavement Base S. Chaiyaput; D. T. Bergado; J. Ayawanna
Lowland Technology International Vol 21 No 3, Dec (2019)
Publisher : International Association of Lowland Technology

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The effect of concurrent use of liquid polymer and Portland cement as a reinforced material in crushed rock pavement base was investigated in this work. The strength of polymer-treated crushed rock (treated crushed rock) and ordinary crushed rock (untreated crushed rock) were characterized and compared. In strength analysis, the California bearing ratios (CBR) of untreated and treated crushed rock were determined under unsoaked and soaked conditions to simulate post-flood pavement damage. The unconfined compressive strength (UCS) was evaluated under unsoaked conditions for 2h, 1-day, 3-day, 7-day, and 28-day curing periods. The results showed that the CBR of untreated and treated crushed rock under soaked and unsoaked conditions were positively correlated with dry density. The CBR under the unsoaked condition of untreated crushed rock was identical to that of treated crushed rock. Meanwhile, under the soaked condition, the CBR of treated crushed rock was twice as higher than the untreated crushed rock. The swelling indices were 0% for both untreated and treated samples. The UCS of treated crushed rock showed positively correlation with the curing time. The use of liquid polymer and Portland cement, therefore, improved the strength of crushed rock pavement base in which effectively mitigate the post-flood pavement damage.
Co-Authors A. Asanprakit A. Bhandari A. S. Balasubramaniam C. Modmoltin C. Pothiraksanon C. Teerawattanasuk D. G. Lirr H. M. Abuel-Naga I. A. Chishtr J. Ayawanna J. C. Chai J. Maneecharoen J. Saowapakpiboon J.-C. Chai N. Chanmee N. Kovittayanon N. Phienwej P. Jamsawang P. Rujivipat P. Voottipruex S. Artidteang S. Chaiyaput S. Chaiyaput S. Chucheepsakul S. Hayashi S. R. Kim S. S. S. Acharya S. Shrestha S. Soralump S. Youwai T. H. Seah T. Hino T. P. de Zwart T. Ruenkrairergsa T. Tanchaisawat W. Mairaeng Y. J. Du Y. Kamo Y. N. Oh Y. Taesiri