Yufang Zhang

The objective of this study is to investigate the potential risks posed by snowdrifts, a prevalent cause of natural disasters in northern China, on railway subgrades, and to assess their risk level. As a wind-driven process of snow migration and redeposition, snowdrifts pose a significant threat to the safety of transportation infrastructures. This study focuses on the Afu Railway in Xinjiang, situated on the northern slopes of the Eastern Tianshan Mountains, where it experiences periodic snowdrifts. We employed a combination of the Analytic Hierarchy Process (AHP) and fuzzy comprehensive evaluation (FCE) to construct an integrated evaluation system for assessing the risk of snowdrift to railway subgrades. The results indicate that subgrade design parameters and regional snowfield conditions are two key metrics affecting the extent of snowdrift disasters, with topography, vegetation coverage, and wind speed also exerting certain impacts. The evaluation method of this study aligns with the results of on-site observations, verifying its accuracy and practicality, thereby providing a solid risk assessment framework for snowdrifts along the railway. The scientific and systematic hazard assessment method of railway subgrades developed in this research provides basic data and theoretical support for future research, and provides a scientific basis for relevant departments to formulate countermeasures, so as to improve the safety and reliability of railway operations.

Case study of the vertical slope excavation near existing buildings based on visual monitoring of intelligent robots is conducted in the paper. A recent development in Western China required the excavation and vertical cut of a rock slope, which might cause large deformation or failure of existing buildings above the slope. The minimum horizontal distance between the buildings and the cut edge of the slope was 3 meters and the maximum excavation depth was 20 meters. The rock slope was composed of soil, weathered mudstone, sandstone and a set of bedding planes inclining outward was observed. Stabilizing piles strengthened by a series of tie-back anchors were designed to protect the cut slope. The lateral loads acting on the anchor cable and piles was determined by maximal value of the at-rest pressure and modified active pressure. It was observed that the construction sequence had a significant impact on the stability of the slopes. To achieve the efficient computer based analysis, the novel visual monitoring system and intelligent robot is combined. The motion control system of the intelligent robot controls the machine equipment and performs industrial operations and the core of the intelligent robot is the motion control system. A novel motion control algorithm is designed to deal with the challenges in complex scenarios. Through the testing on various applications, the robustness is validated.

The landslide at the entrance of a railway tunnel is large scale, and serious diseases are prone to appear under natural disasters, which threaten the safety of the tunnel. According to its characteristics, on‐site long‐term monitoring experiments and numerical analysis were carried out, and the mechanism of interaction between landslide and tunnel engineering was analyzed. The results show that under the impact of rainfall and earthquake, the original internal stress balance in the landslide body is disturbed, leading to the increase in landslide thrust and damage of the tunnel lining. Simultaneously, the excavation of the tunnel can slack the surrounding rock to increase the landslide thrust and make the landslide be finally formed; this landslide conversely acts on the tunnel, resulting in deformation and destruction of the tunnel. During the monitoring, under the influence of rainfall and earthquake, the stress of the secondary lining was continuously increased by 25%. Tunnel construction caused a maximum deformation of 30 mm in the antislide pile at a distance of 2.12 m, and the slope and the tunnel were also affected. Under extreme conditions such as rainfall and earthquake, shear failure occurred at the vault, bottom, and waist of the right‐line tunnel located at the junction of soil and rock; at this time, the tensile strength of the tunnel reached 93.8% of the limit value of concrete, which seriously affected the safety of the tunnel. As for the weakened tunnel structure, measures such as dense planting and strengthening of concrete strength should be adopted to enhance the safety of the tunnel structure.

The landslide at the entrance of a railway tunnel in the southwestern region is relatively large, especially due to earthquakes and other factors, which are prone to severe disasters and threaten the safety of the tunnel. Through the long‐term monitoring test and numerical calculation analysis on‐site, the mechanism of the influence of the earthquake‐induced landslide on the characteristics of the tunnel’s force and deformation is studied. The research results show that the earthquake caused the landslide thrust to increase. Because of the existence of the supporting structure, the landslide thrust was consumed, and the remaining part resulted in the compression failure of the tunnel. During the seismic monitoring period, the stress loss of the antislide pile anchor cable was 3.73% and the stress of the second lining of the tunnel increased by 25%. Under the condition of extreme seismic, shear failure occurred at the vault, bottom, and waist of the right‐line tunnel, and the tensile strength of the right‐line tunnel reached 93.8% of the limit value. For the weak links of the tunnel structure, dense reinforcement planting and strengthening of concrete strength should be adopted to enhance the safety of the tunnel structure. While designing the supporting structure, the rock‐socketing depth of the antislide piles and the number of antislide piles should be considered a priority. The impact of the antislide pile spacing is relatively small.

With the development of the Chinese railway, the high‐steep slope is irreversible to be faced; especially under severe conditions such as heavy rainfall and earthquake, this kind of slope is prone to geological disasters, which seriously affects the safety and stability of the bridge substructure. Aiming to this, long‐term monitorization and numerical analysis were carried out in this research, and the influence mechanism of the high‐steep slopes on the stress and deformation characteristics of the bridge structure was studied. The research results show that under the effect of rainfall and earthquake, the original stress balance in the high‐steep slope is broken, and the possibility of landslide thrust increases; under the comprehensive impact of residual landslide thrust, traction force at slope foot, vertical gravity of bridge slab and vehicle, and the bridge cap will deform. Besides, the deformation of the bridge pier exceeds the allowable lateral displacement of the top of the bridge pier, reaching 111.7%∼112.4% of the limit, which seriously affects the stability of the bridge structure and the safety of the railway service. Therefore, by increasing the support strength of the slope foot and the diameter of the bridge pile foundation, the traction force of the slope foot can be reduced, and the sliding resistance of the bridge pile foundation can be improved so as the safety of the bridge structure can be promoted.