Cable‐supported arch bridges have had many cable break accidents, which led to dramatic deck damage and even progressive collapse. To investigate the dynamic response and robustness of cable‐supported arch bridges subjected to cable breaking, numerical simulation methods were developed, compared, and analyzed, and an effective and accurate simulation method was presented. Then, the cable fracture of a prototype bridge was simulated, and the dynamic response of the cable system, deck, and arch rib was illustrated. Finally, the robustness evaluation indexes of the cable system, deck, and arch rib were constructed, and their robustness was evaluated. The results show that the dynamic response of the adjacent cables is proportional to the length of the broken cable, while the dynamic response of the deck is inversely proportional to the length of the broken cable. The dynamic amplification factor of the cable tension and deck displacement is within 2.0, while that of the arch rib bending moment exceeds 2.0. The break of a single cable will not trigger progressive collapse. When subjected to cable breaking, the deck system has the least robustness. The proposed cable break simulation procedure and the robustness evaluation method are applicable to both existing and new cable‐supported bridges.

In view of clay slope instability caused by environmental temperature and rainfall infiltration in summer and autumn, the mechanism of the effect of temperature and saturation on unsaturated clay slope stability is discussed. To achieve this objective, this study uses theoretical and numerical methods. Based on the theory of unsaturated clay and the law of heat conduction, the relationship between cohesion and matrix suction of unsaturated clay was derived considering the influence of temperature and saturation. Taking into consideration the effects of temperature and saturation, the coupling equation for the shear strength of unsaturated clay was constructed under conditions of rainfall infiltration. The coupling equation for temperature and saturation was used using the strength reduction method, and the slope stability was analysed using FLAC software. The results show that: (i) cohesion in the unsaturated clay slope increases with increasing depth; (ii) the safety factor is smaller when taking into consideration the coupled effect of temperature and saturation than when the temperature effect is not taken into consideration; and (iii) the clay slope is unstable when the coupled effect of temperature and saturation is taken into consideration, but is stable when the coupled effect of temperature and saturation is not considered and soil saturation reaches 80%. Thematic collection: This article is part of the Role of water in destabilizing slopes collection available at: https://www.lyellcollection.org/cc/Role-of-water-in-destabilizing-slopes

Given the structural stability of steel sheet pile support in a water-rich soft soil area, the interaction mechanical mechanism between steel sheet pile support and soft soil was analyzed in the paper. Based on the limit equilibrium theory of soil mass and the coordinated deformation effect of retaining structure and soil, the force equation and action coefficient considering the cohesion of soil and the friction angle of steel sheet pile to soil were obtained. According to the characteristics of the soil around the foundation pit, reasonable supporting spacing (d4m) could be obtained considering the friction angle of the steel sheet pile to soil properly without the cohesion of soil. The monitoring results show that the axial force during the support process is more reasonable considering the cohesion of soil and the friction angle of interaction with the wall and soil. The axial force of the measuring point was affected by the construction site and the layout of the utility tunnel foundation pit. The location with large deformation of the steel sheet pile and the most unfavorable range from the top of the foundation pit was 0.50.7H. For the mechanical analysis of the interaction between steel sheet pile and soil, the apparent cohesion and friction angle can be taken as 0.05rH and φ/3φ/2, respectively. The foundation pit in the water-rich soft soil area could operate stably with a better waterproof effect by the steel sheet pile under different working conditions.

The tie cable of the half-through tied-arch bridge generally uses external prestressed cables, which need to be replaced regularly similarly to cables and suspenders, but there is very little research in this area at present. Aiming at a method to replace the tie cable for this kind of bridge, this study takes the third Lingjiang bridge, which had damage to the tie cable, as an example. Based on whether there is a temporary cable force-replacement structure, eight replacement schemes are designed. Firstly, the replacement process of each scheme is simulated by the finite-element model, and the influence of each replacement scheme on the upper and lower structures is analyzed. Then, according to the analysis results, the replacement schemes were compared and selected, and the best scheme was determined. Finally, based on the best scheme, the design and construction method of the temporary cable force-replacement structure were given. The results show that the replacement of tie cables of the half-through tied-arch bridge significantly impacts the piles. The internal forces of the pile and arch rib change greatly with the non-substitution method. Adopting the temporary substitution method can not only ensure structural safety but also improve the replacement speed, and the temporary substitution method of replacing one by one symmetrically on both sides proved to be the best. This study can provide a reference for the tie cable replacement of a half-through tied-arch bridge.