Slab Upwarping of Twin-Block Slab Track on Subgrade–Bridge Transition Section

Abstract

This study is a preliminary analysis of the causes of upwarping of reinforced concrete slabs of a twin-block slab track, specifically on the subgrade–bridge transition section. The analysis considers the structural features and force characteristics of slab track on the basis of site investigations and numerical simulation, and a corresponding repair method is proposed. It is determined that the temperature and temperature gradient of the slab, the connection status between the slab and the hydraulically bonded layer (HBL), and the position of the terminal spine are the main factors that lead to the upwarping of the slab. Model tests on the force transmission parameters between slab and HBL are carried out to measure the adhesive strength of the cohesive contact and the friction coefficient for the frictional contact. The adhesive strength is found to range from 0.803 to 1.57 MPa. The actual friction coefficient with large dispersion varies significantly from 1.5 to 3.0 because of the influence of the strength of the material and the friction roughness. The analysis output shows that the upwarping of the slab decreases with the reduction of temperature and temperature gradient of the slab, but the upwarping increases with the decrease in adhesive strength and friction coefficient. Increasing the number of terminal spines with 4-m spacing, which is optimized after the spacing effect, contributes to the reduction of the slab upwarping. A reasonable layout scheme for anchor pins can significantly improve the integrity and stability of track structure affected by slab upwarping. From the output of the analysis, a repair method that involves setting additional anchor pins between the slab and HBL is thus recommended.

Long-Term Monitoring for Track Slab in High-Speed Rail via Vision Sensing

“…With the increase of the service time of the high-speed rail (HSR) slab track infrastructure, the deterioration of track geometry caused by slab deformation gradually appears [1]. Typical structural defects associated with the slab deformation include inter-layer de-bonding and slab upwarping [2][3][4] (Fig. 1), which can reduce the track serviceability and compromise the operation safety [5].…”

Behavior and Control of the Ballastless Track‐Subgrade Vibration Induced by High‐Speed Trains Moving on the Subgrade Bed with Mud Pumping

“…Besides, the contact loss between concrete base and subgrade caused by the differential settlement of the subgrade can deteriorate the mechanical properties of the ballastless track structure, causing the increase of the undesirable vibration of the train-tracksubgrade. In order to analyze the vibration of the traintrack-subgrade induced by the contact loss, some vehicletrack-subgrade-coupled system models based on the finite element method have been established, as well as the development experimental model tests [30][31][32]. e increase in vibration of the train-track-subgrade caused by the contact loss adversely affects the comfort and safety of high-speed rail travel and the lifetime of the ballastless track structure.…”

“…e increase in vibration of the train-track-subgrade caused by the contact loss adversely affects the comfort and safety of high-speed rail travel and the lifetime of the ballastless track structure. Repair methods based on the uplift of the ballastless track structure combined with grouting technologies have been proposed to restore the contact between the layers and to reduce the vibration of the train-track-subgrade back to a normal condition [32,33]. Furthermore, repeated mud pumping, which is caused by rainwater infiltration during high-speed railway operation, can squeeze out a large number of fine particles from the subgrade bed through cracks in the expansion joint of the concrete base, as shown in Figure 1, and thus lead to contact loss between the concrete base and the subgrade bed.…”

Energy Method Solution for the Vertical Deformation of Longitudinally Coupled Prefabricated Slab Track

“…Some analytical models have been developed to study upwarping of the coupled slab. Ren et al preliminary analyzed the causes of upwarping of continuously reinforced concrete slabs for a twin-block slab track on the subgradebridge transition section and sorted out a repair scheme for upwarping of track slab through data analysis [3] The slab in the initial state longitudinal force of Bögl longitudinal connected ballastless track on high-speed railway bridge [8].…”