Construction techniques using the drilling and blasting method can markedly influence the stability of surrounding rock formations, posing potential risks such as landslides if not managed properly. Recent research has employed Acoustic Full Waveform Signal analysis to investigate the damage to tunnel surrounding rock caused by blasting activities. This innovative approach effectively monitors and quantifies the effects of cyclic blasting, enhancing our comprehension of rock stability and safety during tunnel construction.
The initiative stemmed from the Chongli Tunnel blasting project of the Beijing-Zhangjiakou High-speed Railway, primarily focusing on the oblique clastic gneiss of the Hongqiyingzi Formation. Researchers constructed formulas for evaluating blasting damage increments, incorporating concepts from elastic wave mechanics. They proposed to analyze Acoustic Full Waveform signals collected before and after blasting, facilitating insight on cumulative damage to surrounding rock due to repeated blasts.
The significance of this study lies not only in the establishment of theoretical frameworks but also practical applications of monitoring techniques. The analysis relied on varying factors including the Lorentz curve, Gini coefficient, and fractal theory to evaluate damage patterns, thereby demonstrating how complex acoustic wave mechanics can reflect underlying geological conditions.
Key findings reveal how blasting damage escalates alongside the number of blasts, but this increment slows over time. The acoustic signal processing highlighted significant shifts: as rock formations were subjected to blasting, various parameters such as wave speed and amplitude exhibited consistent declines, and the frequencies of acoustic waves shifted toward lower ranges. This indicated higher energy dissipation within the rock structure, correlatively reflecting the accumulation of damage.
Understanding the cumulative damage law is imperative, as it relates directly to the mechanical stability of the tunnel and the surrounding environment. The study confirmed the direct correlation between acoustic wave changes and the state of the surrounding rock, underscoring the importance of monitoring to optimize construction practices and mitigate risks associated with blasting.
The research also employed the Gini coefficient alongside the Lorentz curve to quantitatively assess damage distribution, adapting these traditional economic concepts for geological studies. Larger coefficients indicated increased variation and damage complexity within the rock structure, amplifying the significance of these findings for engineering applications.
Additional investigation utilized fractal dimension analysis to address the complexity of damage under varying blast frequencies. Fractal characteristics elucidated how damage patterns evolve, with initial blast-induced fractures displaying self-similarity and irregularity, supporting the notion of localized damage expansion leading to network formations within the rock.
The methodology involved rigorous monitoring, where researchers set up observation points and employed non-destructive acoustic wave detection techniques to gather data about the rock's response to blasting. Consideration for the anisotropic nature of rocks—where different directions exhibit varying properties—was integral to the acoustic wave interpretation process, affirming the necessity for precision and detail during analysis.
This comprehensive exploration exemplifies how newer technologies can contribute to improved assessments of rock stability during tunneling projects. By integrating acoustic monitoring with advanced analytical methods, engineers can gain insightful data leading to enhanced safety measures within construction zones.
Overall, the results deepen the current body of knowledge surrounding tunneling practices, particularly the responses of geological formations to blasting activities, heralding potential advancements toward more sustainable and safe engineering methodologies.