Study on Interlayer Interface Deterioration of Double-Block Ballastless Track in Humid and Hot Environments Based on Acoustic Emission Technique

The deterioration of the interlayer interface of a double-block ballastless track is affected by the environmental temperature and moisture conditions, which will have a negative effect on its service life. Composite specimens with interlayer interfaces of double-block ballastless track were fabricated and deteriorated by an accelerated method, i.e., immersed in saturated ammonium chloride solution with various temperatures for different times. Then, the deterioration condition and mechanical properties of the composite specimens were investigated experimentally by a universal material testing machine and acoustic emission technique. The automatic sensor test (AST) method is capable of assessing the deterioration condition of the interlayer interface based on the relative wave velocity. The deterioration depth of the interlayer interface tends to increase with increasing solution temperature and immersion time. Both the solution temperature and immersion time have a negative impact on the splitting tensile strength and direct shear strength. A linear relation is found between the splitting tensile strength (direct shear strength) and the cumulative AE energy released at the fracture moment. The damage factor defined by the cumulative AE energy for most composite specimens is no greater than 0.2 before they are going to be fractured but increases sharply to 1.0 at the fracture moment.