For the risk of gas leakage and explosion that may occur during the serviceability of urban natural gas pipeline, based on the numerical simulation conducted by FLACS, the gas leakage, explosion and disaster risk under the different speed of wind are mainly studied with local climate characteristics for actual urban street. The results show that the wind speed has an obvious effect on the gas leakage and diffusion, the deviation of gas leakage direction is not obvious for the smaller speed of wind at the initial stage, the horizontal diffusion range gradually increases with the increase of wind speed, while the vertical diffusion range gradually decreases, and the volume of gas at the limit concentration of combustion and explosion gradually decreases. In urban buildings, the overpressure load of higher buildings is lower. After the explosion, the peak overpressure at the same monitoring point decreases with the increase of wind speed. With the increase of distance from the building to the explosion location, the overpressure load on the building decreases and the oscillation effect of overpressure load is relatively gentle. The thermal radiation after burning has great influence on the surrounding buildings and downwind position, especially the buildings around the leakage point.

For the possible damage to overhead pipelines caused by gas explosions in utility tunnels, an overall three-dimensional finite-element model of utility tunnel–soil–pipeline is established, the overpressure loads are applied to the inner wall of the gas chamber in the utility tunnel, the dynamic response laws of the utility tunnel and the pipeline are calculated and analyzed, and anti-explosion protection measures are proposed. The results show that the degree of damage to the pipe wall is determined by both the explosion-impacted area and the soil constraint. Under the same explosion-impacted area, the peak horizontal displacement of the monitoring point without soil constraint is 1.64 times that with soil constraint, and 1.29 times for the peak vertical displacement. The damage to the lower part of the pipeline is significantly greater than that to the upper part of the pipeline, and the damage to the pipeline decreases with an increase in the horizontal angle between the utility tunnel and the pipeline. The diameter deformation rates were 49% at α = 0° and 84% at α = 45°, with α = 90° showing the least damage. Therefore, it is suggested that the overhead pipeline is perpendicular to the utility tunnel. As the vertical distance between the utility tunnel and the pipeline increases, the diameter deformation rate and displacement of the pipeline both decrease, and when this distance is greater than 3 m, the influence on the pipeline significantly decreases. Therefore, it is recommended that the distance between the pipeline and the utility tunnel should be at least 3 m. In addition, the damage caused by gas explosions to the overhead pipeline can be reduced by reinforcing the gas chamber, using energy-absorbing materials around the utility tunnel, and setting up hollow piles between the utility tunnel and pipelines.

This paper analyzes the seismic performance and damage characteristics of high-rise frame-core-tube structures on soft soil, explicitly incorporating dynamic soil–pile–structure interaction (SSI). A refined 3D finite element model of a 52-storey soil–pile–structure system was developed in ABAQUS, utilizing viscous-spring boundaries and the equivalent nodal force method for seismic input. Nonlinear analyses under six seismic waves were compared to a fixed-base model neglecting SSI. Key findings demonstrate that SSI significantly alters structural response; it amplifies lateral displacements and inter-storey drift ratios throughout the structure, particularly at the top level. While total base shear decreased, frame column base shear forces substantially increased. SSI also reduced peak top-storey accelerations, diminished short-period spectral components, and prolonged the predominant period of response spectra. Analysis of member damage revealed SSI generally reduced compressive and tensile damage in core walls, floor slabs, and frame beams. Principal compressive stresses at the base of frame columns increased under SSI. These results highlight the necessity of including dynamic SSI in seismic analysis for high-rises on soft soil, specifically due to its detrimental amplification of forces in frame columns.

Urban subways, as critical strategic spaces, require underground structures with sufficient blast-resistant capabilities. To evaluate the blast resistance performance of underground station structures under ground-level nuclear explosion air shock waves, a three-dimensional finite element model of an underground station was developed using LS-DYNA. The blast mitigation effects of phononic crystals are primarily analyzed and the influence of parameters such as spatial arrangement, buried depth, and material properties of phononic crystals on the blast resistance of underground station structures is systematically examined. The results indicate that a denser configuration of phononic crystals enhances the blast mitigation effect, while the maximum displacement of the structure is increased. Considering the structure’s maximum response and economic feasibility, a spacing of 2 m between phononic crystals is recommended. Additionally, the blast mitigation effect stabilizes when the number of phononic crystal layers exceeds a certain threshold, with two layers being optimal. The buried depth of the phononic crystals has a limited effect on blast mitigation; therefore, positioning them midway between the ground surface and the structure at a depth of 2 m is advised. The material properties of the phononic crystals also have a significant impact on the blast protection. Rubber was found to yield the lowest dynamic response of the station structure, providing the best protective effect. These findings offer insights for designing phononic crystal-based blast protection in underground station structures.