Long Zhou

When only a portion of the shield lining structures in a full-line tunnel are overloaded, their bearing and failure characteristics are significantly diffe

We develop assembled reinforcement structures (ARSs) composed of connection parts, connecting rods, and straight bolts to strengthen segmental joints in th

This study aims to investigate the factors and consequences of gas deflagration accidents in metro shield tunnels based on on-site investigation and numerical analysis. We built a numerical model and detection process for an underground shield tunnel subjected to an internal explosion from an actual accident. The tunnel geometry under consideration is the same as that used for the metro line. Concerning the limitations of research on the failure and recovery mechanism of shield segmental linings under the action of internal explosion load, an explosion accident of a shield segmental lining under construction caused by the shield tunneling machine destroying natural gas pipelines was discussed, in which the structure failure characteristics during the explosion and the structure repair method after the explosion were investigated. An interval repair scheme was proposed, which provides experience for the treatment of similar engineering accidents. To investigate the gas explosion within the tunnel during the accident, the finite element software Ansys LS-DYNA with the arbitrary Lagrangian–Eulerian (ALE) technique was employed to simulate the explosion scenario. Dynamic analyses were carried out to reproduce the blast scenario. The stress distribution within the segmental lining as well as the lining’s deformation were calculated. The potential applications of the treatment and planning of comparable engineering mishaps were discussed in the study.

The lighting design of a road tunnel focuses on the setting of pavement luminance. As for the tunnel sidewall luminance, it simply follows the principle of no less than 60% of the pavement luminance. In fact, the sidewall is one of the important components of the tunnel lighting environment; however, the impact of the improvement of sidewall brightness on the LED lighting environment in a tunnel has not attracted enough attention. In this study, the impact of the improvement of tunnel sidewall brightness on the lighting environment and visual characteristics of human eyes were analyzed based on the lighting experiments when the tunnel sidewalls were decorated with two different types of materials and illuminated by LED lamps with five different color temperatures. The test results show that the tunnel sidewall luminance will increase if the energy-storage and luminescent coating with high reflectance is decorated on tunnel sidewalls, and the pavement luminance increases with the increasing sidewall luminance. After the improvement of the sidewall and pavement luminance, the visible distance for a small object in the tunnel will increase to a certain extent. Furthermore, there is no discomfort for drivers during driving, and the changing of eye pupil diameter is relatively stable, which indicates that the increase in tunnel sidewall luminance has a positive effect on the visual performance of drivers.

The clean production and washing resistance of nano-coating have always been common issues in nano-functional polyester textiles because of the dense structure and chemically inert surface. Here, we developed a clean treatment strategy for preparing washable silver nanoparticle (AgNP)-coated polyester fibers through high-temperature, high-pressure hydrothermal self-assembly of AgNPs in polyester fibers. AgNPs with high affinity to polyester were prepared through the hydrothermal reduction of AgNO ₃ by hyperbranched poly(amide-amine)s. The as-prepared spherical AgNPs possessed a uniform particle size (∼7.52 nm), a positive charge (zeta potential of +54.52 mV), and good dispersibility and chemical stability at 110–130°C. The optimal clean treatment conditions had Ag concentrations of 1–50 mg/L, impregnation time of 2 h, and impregnation temperature of 110°C. Therefore, the Ag content of polyester fibers in the range 0–2,500 mg/kg could be precisely controlled. The as-prepared polyester fibers exhibited excellent antibacterial activities and washing resistance and low Ag release (0.00024% for 24 h). Even when the Ag content was as low as ∼50 mg/kg, the corresponding bactericidal rates increased to 99.99% for Escherichia coli and 99.93% for Staphylococcus aureus . The sample containing ∼200 mg/kg of Ag could achieve up to a 99.99% bactericidal rate for E. coli and 99.9% for S. aureus even after 50 standard washes.