Effect of Interlayer Water on Pore Water Saturation in Ballastless Track

Despite the direct relationship of the durability of ballastless track to the internal moisture content, the distribution characteristics of pore water saturation in ballastless track are unclear. In order to analyze the pore water saturation of CRTSⅡ slab track, the water absorption test was carried out to obtain the sorptivity of CA mortar. Subsequently, the calculation model of saturation in ballastless track was established. A two⁃step calculation process including steady⁃state and transient analysis was designed to determine the initial conditions for transient saturation analysis, and the effects of ambient humidity, interlayer water mode and water absorption time on saturation were analyzed. The results show that the effective porosity of the mortar is 4. 21%, with the sorptivity of 1. 225 5×10-11 m2 / s. In the absence of water, the equilibrium saturation formed in ballastless track follows approximately a trilinear distribution along the depth direction, with 6. 52% maximum annual difference of saturation in the mortar layer. When there is a single crack filled with water under the mortar layer, the saturation in the mortar layer will change from linear to quadratic polynomial distribution along the thickness direction. After seven days of capillary water absorption, the average saturation of the mortar layer increases 37. 6%, with the saturation at the bottom reinforcement in the track slab increasing to 70%, while the affected depth of the interlayer water on the crack front is about 0. 4 meters. When there are two cracks filled with water in the upper and lower interfaces of the mortar layer, the saturation of the mortar layer in the ponding area can reach 100% after 1. 5 days of capillary water absorption. © 2024 Science Press. All rights reserved.