The urban social environment is complex and changeable, and there are accidental and non-accidental explosion risks in tunnels. Performance analysis and assessment after tunnel explosions has become important work. In this study, a prefabricated frame structure (single-layer and double-layer) for urban road tunnels was designed. A three-dimensional refined dynamic response numerical model of a frame tunnel considering the joint effect was established, and the reliability of the modeling method was verified by a full-scale explosion test. Considering factors such as the explosion equivalent (100, 200, 300, and 400 kg), explosion distance (3, 6, 9, and 12 m), and central and external explosions, the deformation characteristics and damage evolution law of the prefabricated frame tunnel after the explosions were explored. The deformation failure mode of the prefabricated frame tunnel was analyzed. The study shows that the roof of a single-layer tunnel and the mid-partition of a double-layer tunnel are weak components of a prefabricated frame tunnel with steel column joints under a central explosion load. The deformation and damage at tunnel joints are greater than those at other positions. Under an external explosion load, the closer the explosion point is, the greater the damage and deformation of the prefabricated frame tunnel lining are. Furthermore, showing a high degree of locality. With the equal amplitude increase of the detonation distance (3–6 m, 6–9 m, 9–12 m), the lining displacement is relatively reduced by about 75.7%, 39.9%, and 10.0%, respectively, and the lining deformation is mainly represented by the overall bending deformation.

A low-clearance tunnel portal in the shallow-buried, joint-developed, broken, and loose surrounding rock slope deposit may cause safety issues during construction. In this study, the Guanyin Mountain Tunnel of the Chong-Ai expressway was taken as a case study, and the characteristics of the loose and broken surrounding rocks, their low clearance, and shallow buried bias were comprehensively studied. The three-dimensional numerical model of the Guanyin Mountain tunnel portal section was constructed by the Rhino, AutoCAD, and FLAC 3D software, and the whole construction process of the tunnel portal was simulated. Under the conditions of loose and broken surrounding rocks, the surrounding rock deformation, surface settlement, and slope stability at the portal of the shallow buried tunnel with a small clear distance during the construction of the center diaphragm (CD) method and circular reserved core soil method were studied. The following conclusions are drawn. During the simulated excavation of the tunnel, the maximum surface settlement is 10.74 mm, which meets the requirement of the specification. When the left tunnel is excavated, the surrounding rock deformation of the right arch shoulder should be carefully considered. The maximum deformation value can reach 14.314 mm. After excavation, the deformation rate of the right tunnel is large, and initial support should be installed in time. Since the stratum rock at the portal of the tunnel is strongly weathered, the uplift value of the arch bottom is large and gradually decreases along the axial direction. The tunnel arch bottom and arch foot are plastic areas prone to tensile damage. Therefore, it is imperative to strengthen the inverted arch support of the tunnel in the strongly weathered rock stratum. The excavation sequence of the tunnel portal section adopts the method of excavating the left tunnel first and then excavating the right tunnel, which is more conducive to ensuring the slope stability.

The application and promotion of grouted sleeve connectors in prefabricated structures are closely related to their high efficiency and intensive advantages. Numerous scholars have conducted experimental studies on the performance of sleeves, but there has been no systematic consolidation of these efforts. In this study, the latest developments in grouted sleeve connection technology are systematically reviewed and analysed, focusing on its applications and characteristics, performance testing, influencing factors, load-transfer mechanisms, and performance evaluation. First, the differences in sleeve code formulation across various countries are compared, the advantages and disadvantages of different sleeve types and grouting techniques are reviewed, and the application scenarios of sleeves are summarized. Second, an overview of the performance of grouted sleeves in tensile, fatigue, and seismic tests is provided, highlighting key factors affecting structural performance and experimental results. Furthermore, the effects of various factors (the anchorage length, diameter and strength of reinforcing bars; types and defects of grout materials; sleeve tube design; and temperature) on the performance of sleeves are investigated, and some beneficial conclusions are drawn. The load-transfer mechanisms of different sleeve types are subsequently compared, and the common features of the sleeves that meet the performance evaluation criteria are analysed. Finally, potential future research directions and innovations in sleeve technology are suggested to provide researchers and scholars with innovative ideas and research perspectives for developing new sleeves and advancing the application of grouted sleeve connectors.

As the main structural bodies of underground facilities such as subway stations, frame tunnel structures play an important role in urban development and construction. In recent years, with the frequent occurrence of explosions after vehicle impacts in tunnels, which have caused severe damage to frame tunnels, the lack of relevant papers makes it necessary to develop a dynamic response analysis of frame tunnels. In this paper, by optimizing the design of an original frame tunnel structure, a dynamic response numerical model of the frame tunnel considering the impact effect of a 3D solidified vehicle and the joint effect is investigated. The deformation trend and damage evolution of the frame tunnel are analysed under different collision masses (1.4, 2.4, 6 and 15 t), collision angles (5, 10, 15 and 75°), collision speeds (60, 80 and 100 km/h), blast delay times (10, 20 and 30 ms) and blast equivalents (50, 100 and 200 kg TNT). This paper improves the active and passive robustness of frame tunnels using both improved operational management and the optimal design of the tunnel structure as a way to ensure the structural safety and functional resilience of frame tunnels.