Water-Sealed Blasting Control Measures of the Metro Station Undercrossing Existing Structures in Ultra-Close Distances: A Case Study

Abstract

Based on the project of People’s Hall Station of Qingdao Metro Line 4 in China, the method of water-sealed blasting construction for vibration damping is proposed, as the blasting vibration of adjacent structures (Qingdao Metro Line 3) does not meet the control requirements during the blasting construction of the existing site blasting scheme. The effects of blasting on adjacent structures with different water-sealed charge structures and different axial decoupled charge factors are first studied by using the three-dimensional dynamic numerical simulation method. On this basis, a multi-case parametric analysis is carried out on the maximum single detonation charge, initiation interval, vibration-damping hole settings, and other factors that affect the blasting seismic effect. The results demonstrate that water-sealed construction blasting can significantly reduce the vibration response of adjacent structures. The lower-water-decking charge structure, the two ends-water-decking charge structure, and the top-water-decking charge structure can reduce the vibration velocity response of adjacent structures by 2.8, 24.5, and 27.8%, respectively. As the axial decoupling coefficient increases, the peak resultant vibration velocity increases first and then decreases. The peak resultant vibration velocity reaches the minimum value of 1.27 cm/s, which is lowered by 29.5% when the decoupling coefficient is 2.6. The after-detonation vibration response can be reduced by decreasing the amount of a single detonation charge and setting damping holes. When the detonation charge is reduced to 2.7 kg or 100 mm damping holes are set up, the vibration velocities at Line 3 People’s Hall Station are 1.10 cm/s and 1.11 cm/s, respectively. Both velocities are less than the 1.2 cm/s resultant vibration velocity control tolerance requirements. The results of this study can play an important guiding role in construction blasting in on-site metro stations and can serve as a reference for future similar projects.

Investigation of the Influence Area of the Excavation of a Double-Line Highway Tunnel under an Existing Railway Tunnel

“…The blast load waveform adopts the triangular load waveform, the peak load is reached quickly at 10 ms, and the unloading time is 100 ms. The peak load is determined by the empirical formula according to the literature [42], and the empirical formula is as follows:…”

Stability analysis of civil air defense tunnel under blasting vibration

“…Most of the existing studies are carried out based on numerical simulation. Among them, Wang Qiuyi [1] et al studied the changes in vibration frequency and amplitude in the tunnel and obtained the dynamic response characteristics of the tunnel at different locations. Li Qingsong et al used finite element numerical analysis to study the change characteristics of the tunnel and analyzed the distribution law of the dynamic response [2].…”