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 หัวเรื่อง:ไม่มีชื่อไทย (ชื่ออังกฤษ : Interaction between Geogrid and Tire Chips-Sand Mixture: Pullout Test Simulation) ผู้เขียน: ดร.ธวัชชัย ตันชัยสวัสดิ์, อาจารย์ ,  Dennes T. Bergado สื่อสิ่งพิมพ์:pdf AbstractThe aims of the study were to measure and calculate the interaction coefficient between geogrid and sand and between geogrid and a tire chips-sand mixture using a laboratory test and numerical simulations. Numerical simulation was imperative for the sensitivity analyses of the laboratory test results to find the important parameters. Two types of material were used as backfill, namely sand and a tire chips-sand mixture. The sand and tire chips in the mixture were in the proportion by weight of 70 and 30%, respectively. Polyfelt geogrid was used as geosynthetic reinforcement with a tensile strength of 97.48 kN/m from the in-air tensile test. Pullout tests were carried out on a large-scale pullout machine. The shear strength parameters of Ayutthaya sand and the tire chips-sand mixture were a 29.8? friction angle with cohesion of 15.6 kPa for sand and a 24.4? friction angle with 14.3 kPa cohesion for the tire chips-sand mixture. The results revealed that the interaction coefficient obtained from the pullout test was 0.7 and 0.6 for the sand and tire chips-sand mix, respectively. Numerical analyses were also performed using finite element software. The results of the numerical simulation agreed reasonably with the laboratory results. Sensitivity analyses were carried out for the pullout test by varying the interaction coefficient and axial stiffness of the geogrid. These two important parameters were found to affect the efficiency of the geogrid reinforcement. |
หัวเรื่อง:ไม่มีชื่อไทย (ชื่ออังกฤษ : Enhancement of PVD Performance by Thermal and Electro-Osmotic Techniques) ผู้เขียน:ดร.ธวัชชัย ตันชัยสวัสดิ์, อาจารย์, Dennes T. Bergado, Jaturonk Saowapakpiboon สื่อสิ่งพิมพ์:pdf AbstractThis paper examines the innovative techniques for enhancing the performance of the prefabricated vertical drain (PVD) consisting of thermal and electro-osmotic consolidation techniques. The electro-osmotic consolidation of soft Bangkok clay was first studied. Laboratory testing program were done on undisturbed and reconstituted sample in large consolidometer under voltage gradient of 60 and 120 V/m with 24 hours polarity reversal. The time to achieve 90% degree of consolidation induced by electro-osmosis ranged from 1.4 to 2.1 and 2.1 to 2.2 times faster than the normal consolidation with PVD only, for undisturbed and reconstituted samples, respectively. Faster rate of consolidation and higher magnitudes of settlement were achieved at higher voltage gradient. Subsequently, the performances of thermo-PVD which involves increasing simultaneously both the vertical effective stress and the surrounding clay temperature up to 90?C were investigated using the large consolidometer. The test results demonstrated that higher consolidation rates were observed for the clay specimen at elevated temperatures for both undisturbed and reconstituted specimens. This behavior can be attributed to the increase in the clay permeability with temperature. Therefore, raising the clay temperature can enhance the performance of PVD by reducing the drainage retardation at the smear zone around the PVD. |