Evaluating Grid Frame-Type Railroad Derailment Containment Provisions with Drop Weight Impact Testing

Abstract This study evaluates the structural performance of newly designed and fabricated grid frame-type railroad DCPs (derailment containment provisions) classified as DCP type I, compatible with rapid assembly construction and maintenance on gravel tracks in railway service lines. Previous research only reviewed the durability of the structure under static loading conditions. However, this study proposed an evaluation method considering the importance of assessing the impact performance of the DCPs assembly structure subjected to dynamic impact loads from continuously colliding train wheels; this involved a drop weight test to analyze the behavior of the DCP assembly structure under accumulated impact energy applied to different collision positions. To this end, drop-impact weight tests were conducted to verify the structural performance of the derailment protection system connected to concrete sleepers using post-installed anchors. A test specimen and jig were fabricated to evaluate the structural performance and impact resistance of the anchoring connections. 15 drop weight impact tests were performed, and the resulting behavior under impact energy was analyzed. The results indicated that when a derailed train wheel collides with the DCP frame section, dominant loads act on the base plate anchor, resisting through shear and bearing strength of the anchor bolts. The DCP assembly structure demonstrated sufficient derailment containment performance, even under significant accumulated energy (21.0 kJ; six repeated impacts), with collision loads and displacement levels within acceptable limits. For repeated impact loads (3.5∼7.0 kJ; 1∼2 occurrences), the impact load absorbed by the DCP connection anchor averaged 241.22 kN, and the vertical displacement at the collision point averaged 14.23 mm. This value is 2.62 times (162%) greater compared to the case of a collision on the DCP frame and approximately 13% lower than the impact load that the DCP frame can absorb. Additionally, when a derailed wheel collided directly with the side of the base plate, the embedded anchors in the sleeper were identified as a relatively weak point. Therefore, reducing the base plate width (from 500 mm to 480 mm) to guide collisions toward the DCP frame section, which could absorb greater impact loads, was a more effective design. The test results demonstrated that the newly developed steel grid frame-type DCP combination structure sufficiently resists the impact loads from derailed wheels of high-speed trains traveling at 300 km/h. It effectively restricts excessive lateral movement of derailed trains and provides guiding capability. Furthermore, the drop weight test for the newly proposed DCP combination structure, which also considers impact energy, is deemed more suitable for analysis than conventional testing methods.