การประเมินหน่วยแรงและการเสียรูปที่เกิดขึ้นของถุงจีโอเท็กซ์ไทล์บรรจุทรายภายใต้เงื่อนไขน้ำ หนักแบบกดบนพื้นฐานการพัฒนาเสถียรภาพความลาด

Abstract

The thesis aims to study the strength and deformation of geotextile bags filled with sand and the effect of the size of the filling sand under compressive loading. Then, the numerical model of a single sandbag is simulated by numerical analysis based on a finite element method for slope stability improvement. The testing results were obtained from the vertical compressive loading test without 1- directional lateral displacement, which the test was designed including to geotextile bags, materials, and testing equipment for application in this research especially, to support the 2-dimension model. There were 3 sample sand sizes of uniform-graded particles packed in bags. The test results show all sandbags have a highly bearing capacity with increasing strength, which increases slowly in the early vertical strain then increases steadily and increases significantly in the final vertical strain. The horizontal deformation behavior of all 3 sandbags is greater than vertical deformation, which is 2 times of vertical strain approximately in the initial vertical strain, after that it decreases and be constant until the final strain at 1.30 times of vertical strain approximately. The geotextile bags containing sand show the volume change behavior. At the first 5 percent of vertical strain, the volume of the sandbags increases due to (1) the arrangement of sand particles in the bag (2) the expansion of the geotextile and (3) the expansion of thickness of the geotextile. After that they continue to decrease the volume until the end of the test. This is due to a change in the width-to-height ratio of the bag and particle breakage during the test. However, there is the increase in volume while the volume was decreasing during this period due to the orientation of the sand, the expansion of the geotextile upon tensile strength and the dilation between the sand particles. The effect of the filling sand size has no effect on the deformation ratio of the sandbag. But it affects the stress behavior before the 25 percent vertical strain. It can be concluded that this period is mainly influenced by the shear strength of the filling sand. In contrast, after 25 percent vertical strain is the period mainly influenced by the tensile applying of the geotextile. The numerical analysis based on finite element method by PLAXIS2D program, which is based on the relational equation of Matsuoka and Liu (2003) to model the combined material model between geotextiles and sand. The modelis necessary to determine the volumetric strain before the analysis. This modelcan produce results of vertical and horizontal deformation that tend as same asthe test results. The stress results obtained in the model analysis tendsto be in the same range as in the test, only about 0-25 percent of verticalstrain. However, the slope stability improvement is sufficient for applicationin design with a limit of 25 percent vertical strain. The applying of the modelgreater than the limit strain should be aware of the results due to calculations and should be considered further.