With the increase in the mileage of high‐speed railways around the world, subgrade problems related to the same have been emerging in large numbers. In view of the shortcomings of slow construction speed and large disturbance caused by conventional anti‐slide piles during emergency reinforcement of subgrades, an “arch–chord coupled anti‐slide structure” is proposed in this study, based on the three‐dimensional characteristics of the subgrade creep, and its anti‐slide mechanism is analyzed; furthermore, a theoretical calculation method for the same is proposed. The results show that the arch–chord coupled anti‐sliding structure can form a coupled body containing multiple surrounded piles when subjected to thrust, thus offering a pile–soil composite structure similar to a retaining wall. This results in a large anti‐sliding force. By setting a virtual pile to regularize the layout of the structural pile, the pile internal force can be accurately computed. The findings of this study provide a theoretical basis for the analysis and design of coupled anti‐sliding structures in future.

Arch‐chord coupled anti‐sliding structure is a new type of anti‐sliding structure composed of multiple single piles in a specific form. The coupling effect of pile and soil is the most important key point. In this article, the factors that affect the coupling bearing capacity and load sharing ratio of the arch‐chord coupled anti‐sliding structure are screened out, and the rule that the evaluation index is affected by each factor is analyzed. The results show that, with the increase of pile diameter, the value of structural coupling ultimate bearing capacity increases exponentially, but the growth rate slows down gradually. With the increase of pile spacing, the value of structural coupling ultimate bearing capacity decreases. With the increase of soil cohesion around the pile, the value of structural coupling ultimate bearing capacity increases linearly. The coupling ultimate bearing capacity and load sharing ratio of the anti‐sliding structure are the most sensitive to the change of the internal friction angle of the soil around the pile, and the pile diameter has little effect on the evaluation indexes.

The slope of an open cut tunnel is located above the exit of the Leijia tunnel on the Changgan high-speed railway. During the excavation of the open cut tunnel foundation pit, the slope slipped twice, a large landslide of 92500 m³ formed. The landslide body and unstable slope body not only caused the foundation pit of the open cut tunnel to be buried and the anchor piles to be damaged but also directly threatened the operational safety of the later high-speed railway. Therefore, to study the stability change in the slope of the open cut tunnel under heavy rain and excavation conditions, a 3D numerical calculation model of the slope is carried out by Midas GTS software, the deformation mechanism is analyzed, anti-sliding measures are proposed, and the effectiveness of the anti-sliding measures is analyzed according to the field monitoring results. The results show that when rainfall occurs, rainwater collects in the open cut tunnel area, resulting in a transient saturation zone on the slope on the right side of the open cut tunnel, which reduces the shear strength of the slope soil; the excavation at the slope toe reduces the anti-sliding capacity of the slope toe. Under the combined action of excavation and rainfall, when the soil above the top of the anchor pile is excavated, two potential sliding surfaces are bounded by the top of the excavation area, and the shear outlet is located at the top of the anchor pile. After the excavation of the open cut tunnel, the potential sliding surface is mainly concentrated at the lower part of the downhill area, and the shear outlet moves down to the bottom of the open cut tunnel. Based on the deformation characteristics and the failure mechanism of the landslides, comprehensive control measures, including interim emergency mitigation measures and long-term mitigation measures, are proposed. The field monitoring results further verify the accuracy of the anti-sliding mechanism analysis and the effectiveness of anti-sliding measures.

In this study, the damage mechanism due to near-fault ground motions on large-span arch bridges with concrete-filled steel tubes was investigated based on a case study. A tied-arch bridge with concrete-filled steel tubes with a span of 460 m has been examined using the numerical simulation method. The performance of the bridge was analyzed in terms of displacement, overall response, internal force changes, and damage probability considering the various near-fault and non-near-fault ground motions when imposing load onto the bridge. Then, the relationship between the bridge damage and the design parameters of ground motion intensities, near-fault velocity pulse, and excitation angle was obtained. The results indicated that the probability of damage caused by near-fault earthquakes is significantly higher than that by non-near-fault ground motions, and velocity pulses may cause more severe damages to certain components of the bridge during lower-intensity ground motions at certain excitation angles. And the damage furtherly resulted in the weakening of the bridge structure and decrease in its load-carrying capacity. Therefore, the near-fault ground motion should be fully considered in the design of large-span arch bridges with concrete-filled steel tubes in practical engineering.

Arch-chord-coupled antisliding structure is a new type of structure composed of multiple small-diameter piles for strengthening small- and medium-sized landslides, especially suitable for the reinforcement of slopes that are sensitive to deformation. In order to further explore the mechanical properties of the antisliding structure, physical model tests under four cases were carried out to study the deformation and stress characteristics of the structure under different types, and the optimal structural type was determined. The displacement test results show that even if there is no crown beam at the top of the piles, all the piles can deform in coordination, and when the number of rear piles is large, all the piles can basically deform synchronously. The test results of the bending moment of the pile body show that the crown beam has a great influence on the extreme value of the bending moment of each pile. For the structural type with more piles arranged in the rear row, the standard deviation of the extreme value of the bending moment of the pile body before and after adding the crown beam decreases from 2.0 to 1.03; the presence of crown beams effectively adjusts the internal force of each pile. The comprehensive analysis results show that the arch-chord-coupled antisliding structure with more piles in the rear row is the best.