การประเมินสัณฐานวิทยาและประสิทธิภาพของหินโรยทางรถไฟที่ใช้งานแล้วจากกระบวนการเร่งการเสื่อมสภาพในห้องปฏิบัติการ บนพื้นฐานของการจำลองเชิงตัวเลข

Abstract

At present, the rail transport system has played an essential role in transportation in Thailand. The rail system is considered the most cost-effective transportation system. There are high transport limits. It is economical, safe, and emits little pollution when calculating the same amount of transportation. As mentioned above, developing the rail system to be more efficient is essential. Considering the railway system, it will be found that it has mainly deteriorated because of the settlement of the substructure. Ballast is the most crucial component of the substructure because it is the only external constraint applied to the track to restrain it. As mentioned above, ballast is important for the railway system. Currently, in Thailand, there is no study of the deterioration behavior of ballast at the laboratory level. There are no examples of deteriorated ballast on the actual site. In addition, there needs to be a clear guideline for studying the morphology of ballast that affects its strength. This research investigates a method for simulating the acceleration of the deterioration of fresh ballast at the laboratory level to have the same properties as used ballast using a Los Angeles machine. Use the fouling index and the void contamination index to measure the degree of ballast deterioration and study the change in particle size distribution as the rotation of the testing machine increases. At the end of this process, used ballast is obtained through an accelerated deterioration process in the laboratory. The morphological properties between fresh and used ballast were evaluated using flatness, elongation, convexity, sphericity, and roundness index in the evaluation through image processing by 3D scanner and MATLAB. Final, preliminary assessment of mechanical properties of Fresh and used ballast by 2D Biaxial shear test through the discrete element method using the LMGC90. The results of the study found that accelerating the deterioration of ballast in the laboratory using a Los Angeles machine at 3,500 cycles caused the ballast fouling index to be greater than or equal to 40 and void contamination index greater than or equal to 100 and become used ballast. The morphology study found that fresh ballast and used ballast have similar morphology, with the significant difference being the convexity, sphericity, and roundness index values. It can be explained that when ballast has a convexity value less than 0.9 and a sphericity value less than 0.8, it is likely to be fresh ballast. When a ballast has a convexity value greater than 0.9 and a sphericity value greater than 0.8, it is likely to be used ballast. Regarding studying the mechanical behavior at both the macro and micro levels of ballast, the overall mechanical behavior of fresh and used ballast was similar. It is possible to develop used ballast further and reuse it again.