Asphalt pavements are prone to various distresses under complex environmental influences during service, which significantly affects their fatigue life. This study conducted complex environmental simulation tests, including pressure aging, ultraviolet (UV) aging, and coupling effects with salt solutions at different concentrations. A dynamic shear rheometer (DSR) was employed to perform frequency sweep tests, linear amplitude sweep (LAS) tests, and fatigue–healing–fatigue tests. The fatigue self-healing properties of fast-melting SBS (SBS-T)-modified asphalt were evaluated based on the viscoelastic continuous damage theory. The results indicate that coupled aging effects significantly increase the viscoelastic characteristic parameters of SBS-T-modified asphalt, with more elastic components transforming into viscous components. Compared to other aging effects, the coupled pressure-UV-salt solution condition induces the most severe degradation in the fatigue durability of SBS-T-modified asphalt. Simultaneously, the self-healing capability of aged asphalt is also reduced. Specifically, with increasing strain, more complex aging conditions lead to the faster deterioration of asphalt fatigue life and lower self-healing capacity. While asphalt demonstrates measurable fatigue life restoration through self-healing, the synergistic coupling of salt solution exposure and multi-factor aging significantly compromises both the absolute fatigue resistance and the relative recovery efficiency.

In shield tunneling, ensuring bonding performance at new-to-old concrete interfaces between segments and linings is crucial for composite lining stability. While extensive research exists on the mechanical bonding behavior of such interfaces, comparative studies on two prevalent treatment methods—scabbling and grooving—remain limited. This study systematically evaluates these techniques’ effects on interfacial bonding via direct shear tests, benchmarking against smooth-interface specimens. Complementary cohesive zone modeling simulations further analyze stress distribution and damage evolution during shear failure. The results demonstrate that scabbled specimens exhibit 10.5%~18.2% higher shear strength than grooved counterparts under increasing normal stress, with both treatments significantly enhancing load–transfer synergy through mechanical interlocking. Furthermore, the energy-based bilinear cohesive model accurately predicts full-interface behavior, providing practical guidance for interface treatment selection in tunneling engineering.

This paper introduces an alternative method for determining the shear strength parameters of concrete materials, specifically the rectangular section splitting method, to ascertain the shear strength parameters of concrete materials. Based on the Mohr–Coulomb failure criterion, formulas for calculating the cohesion (c) and the angle of internal friction (φ) of concrete materials are derived. Numerical simulation is employed to fit and solve for the coefficients involved in the formulas. Subsequently, the concrete rectangular section splitting method and direct shear tests are utilized to verify the derived formulas. The results indicate that there is a certain feasibility to the shear strength parameters obtained for concrete materials through the rectangular section splitting method. The cohesion (c) differs by approximately 3.65%, and the angle of internal friction (φ) differs by about 6.94% when compared to the shear strength parameters obtained through direct shear tests. This suggests that the rectangular section splitting method provides a viable approach for determining the shear strength parameters of concrete materials.

Aiming at the challenges of lining cracking and water seepage in water conveyance tunnels under high internal water pressure, joint waterproofing is the key to improving the structural anti-seepage performance. This paper investigates the mechanical and anti-seepage properties of joint sealing materials, as well as the stress-deformation characteristics of the anti-seepage structure. Uniaxial tensile tests, bond tensile tests, and interfacial shear tests were conducted on three types of sealants—polysulfide, polyurethane, and polyurea—to systematically obtain the fundamental mechanical parameters. The results show that polyurea has the highest ductility, polysulfide exhibits the highest tensile strength (1.27 MPa), and polyurethane presents balanced performance. The interfacial shear strength between polysulfide and concrete reaches 0.5 MPa, demonstrating outstanding bonding performance. Based on the cohesive zone model, a numerical model of the joint sealing system was established to analyze the evolution of stress and deformation under two working conditions: inner-side water seepage and double-sided (inner and outer) water seepage. The results indicate that water pressure induces stress peaks at the contact interface between the sealing material and the segment. The stress peak under internal water pressure alone is significantly higher than that under combined internal and external water pressures. Comprehensive comparison shows that polysulfide sealant offers better stability in resisting internal water pressure and controlling deformation. The selection of sealant type in engineering should consider the stress characteristics, deformation requirements, and construction conditions of different structural locations.