To achieve the efficient, rapid construction of prestressed anchor cables, in this study, through an indoor pull-out test and field basic test, we investigated the mechanical behavior, expansion, drawing performance and bond properties of a new type of high-strength, fast anchorage agent. We analyzed the influence of the water material ratio and curing time on its performance and determined the corresponding construction. It was found that the new anchoring agent could be effectively applied in field construction and achieved a compressive strength of 30 MPa within 30 h. Moreover, during the solidification process, the hydration reaction node could be reached within 5–6 h when the material expansion was and the feedback to the water–material ratio were the strongest. In addition, in the drawing process, the anchorage agent exhibited a strong bond with the reinforcement and the rock layer, and the bonding of the anchorage agent to the rock layer was greater than that of the steel bar. Therefore, in order to provide anchorage, it is necessary to increase the contact area between the steel strand and the anchorage agent.

This article focuses on the effect of freeze–thaw cycling on a cement-based early-strength anchor material, the compressive strength of which at 24 h is 14 times that of ordinary cement, and the compressive strength at 7 h is twice that of ordinary cement. The setting time required to achieve the expected strength is 1/7 of that of ordinary cement. Through indoor freeze–thaw cycling tests, the appearance changes, quality loss, strength loss, and microstructure changes in the early-strength anchor after 0, 5, 15, 25, 50, 75, and 100 cycles were studied, revealing the evolution of the mechanical properties and micromechanisms of the cement-based early-strength anchor material under freeze–thaw cycling conditions. The sample freeze–thaw failure criteria were determined, evaluation indicators reflecting the degree of damage were defined, and their relationships with the number of freeze–thaw cycles were fitted to assess the durability of the cement-based early-strength anchor material under freeze–thaw environments. This provides a theoretical reference for further improvements in material properties and adaption to different environments.

Due to the complex hydrogeological conditions in coastal regions, the use of internal bracing systems is necessary for supporting coastal foundation pits. This paper introduces a novel prefabricated foundation pit bracing system based on Hollow Concrete-Filled Steel Tube (H-CFST) structures that can be reused, offering significant economic and societal benefits. However, there is a severe lack of research on the application of H-CFST bracing systems. Through model tests and finite element simulations, the load-displacement characteristics and failure modes of prefabricated H-CFST bracing under transverse bending were investigated. The study revealed that when a wall thickness of 1.5 d was chosen, the self-designed hoop effectively mitigated strength and stiffness reduction at the bracing connection point. When the load reached 150 kN, the outer steel tube of the H-CFST components experienced localized yielding, and when the load was increased to 300 kN, the end supports exhibited cracking. Finite element analysis provided a more accurate prediction of bracing failure at 147.18 kN, and it offered valuable insights for optimizing the bracing design. Based on the above research, theoretical methods for calculating the bearing capacity of each bracing component under transverse bending conditions have been proposed and validated against experimental results.

Underground space development is a crucial approach to addressing traffic congestion in China’s cities, especially through underground construction. However, the traditional pit internal support system, particularly the concrete internal support system, has significant drawbacks. These include high energy consumption and carbon emissions, which are increasingly prominent issues. In this paper, a hollow precast concrete-filled steel tube (H-CFST) internal support system is proposed and a node connection scheme is designed. Through numerical simulation, the load-bearing characteristics of H-CFST with different aspect ratios, hollow ratios, hoop thicknesses, and hoop lengths are investigated, and the optimal design parameters are obtained. Finally, following a field application, monitoring data reveal that the precast H-CFST internal support demonstrates superior load-bearing capacity compared to the concrete internal support, successfully meeting the criteria for replacement of the concrete support.