# Safety Assessment of the Cover-and-Cut Method Under Blasting Vibration Induced by Tunnel Excavation
## 1 Introduction  
### Challenges and Advances in Vibration Control for Urban Tunnel Construction  
The cover-and-cut method has become popular for tunnel and metro station construction due to its efficiency and minimal disruption to surrounding areas. This study focuses on the Guiyang Metro Line 3, specifically the Guizhou University Station, which presents unique geological and construction challenges. The project site involves mixed artificial fill, clay, karst formations, and argillaceous dolomite, conditions rarely addressed in previous studies. By analyzing blasting vibration effects under these specific circumstances, this research contributes practical insights into urban metro construction safety [1, 2, 3]. However, when blasting is used in tunnel excavation, vibrations can propagate through nearby structures, potentially causing damage or even collapse. Ensuring structural safety in these conditions requires precise control of blasting vibrations. Blasting-induced vibrations impact various structural elements, such as foundation pits, retaining walls, and bridge columns. Understanding the propagation and interaction of these vibrations with adjacent structures is crucial to prevent lasting damage. Research shows that both the intensity and frequency of seismic waves significantly affect structural integrity, with vibrations within a structure's natural resonance range posing a heightened risk. In urban subway projects, where adjacent buildings are common, vibration control is essential to ensure public safety [4, 5, 6, 7]. Numerous studies have examined the effects of blasting vibrations [8; 9; 10]. [PERSON] et al., for instance, developed empirical models to predict vibration amplitude and frequency in subway tunnels [11; 12; 13]. [PERSON] used finite element simulations to study seismic wave behavior in rock surfaces, demonstrating how deep tunnel blasts can create high-amplitude waves on the surface. Other studies focus on how underground blasting impacts infrastructure like roads, pipelines, and existing subway tunnels, emphasizing the role of wave intensity and frequency in determining vibration-induced damage [14; 15; 16; 17]. [PERSON]'s research employed 3D Distinct Element Code simulations to predict surface structural damage from tunnel blasting [18], linking damage severity to both wave intensity and frequency [19; 20; 21; 22]. Yet, most studies emphasize vertical loads, pressure effects on diaphragm walls, and settlement of surrounding structures, with less attention to the specific impacts of blasting vibrations on diaphragm walls, roof plates, and central columns within foundation pits [23; 24; 25]. To address this gap, this study investigates the Guizhou University Station on Guiyang Metro Line 3, where the cover-and-cut method is used. Field tests and simulations using FLAC3D software assess how vibrations from multiple blasting cycles affect critical structures, such as diaphragm walls, central pillars, and roof plates. The three-dimensional model provides insights into vibration velocity, frequency distribution, and structural responses to repeated blasts [26; 27]. The assessment of blasting vibration impacts on underground structures, especially those caused by subway tunnel excavations, has become a critical area of research in geotechnical and structural engineering. [PERSON] developed a 3D numerical model for assessing the safety of a buried DN1200 water pipeline subjected to blasting vibrations from subway tunnel excavation. The model, validated by field blasting monitoring data, indicated that the pipeline remained safe in both empty and water-filled states under blasting-induced vibrations, using a parallel cut blasting method. In a related study, [PERSON] explored the blasting vibration response in an existing railway cross tunnel, examining the evolution of peak particle velocity and frequency. The study introduced a dimensional analysis method for evaluating the influence of frequency on vibration response, incorporating wavelet packet analysis and structural dynamics.