## 1 Introduction  
Tunnel blasting plays a pivotal role in modern subsurface engineering, particularly in the construction of essential infrastructures such as railways and highways. The effectiveness of blasting operations significantly influences not only the structural integrity of tunnels but also safety, cost-efficiency, and environmental impact. An essential aspect of evaluating blasting effectiveness is the assessment of half porosity, which refers to the residual voids left in the rock mass post-blasting. Half porosity serves as a critical indicator of blasting precision, as a higher rate of visible holes suggests better control over the blasting process and minimal overbreak. This metric is widely used to evaluate the quality of smooth blasting, ensuring that the energy from the blast is efficiently utilized and the tunnel wall remains as close to the design as possible [1]. Accurate measurement of half porosity is crucial for determining the quality of the excavation and ensuring compliance with engineering specifications. As tunnel construction projects grow in complexity, recent advancements in evaluation methodologies have highlighted the necessity for improved techniques to assess blasting effects comprehensively. Optimizing blasting parameters remains essential for enhancing both operational efficiency and safety in underground construction. Foundational studies in this field have examined how blast hole patterns and controllable blasting parameters impact rock fragmentation and overall structural stability, establishing principles that inform more effective blasting designs. Recent research has further emphasized the importance of maximizing half porosity, which allows for improved control over the blasting process and helps to minimize material waste. Collectively, these advancements reflect a growing emphasis on precision and sustainability in tunnel blasting practices, underscoring the field's continued evolution towards more refined and efficient techniques. Further progress has been made in 3D reconstruction and visualization techniques, which are essential for accurate and reliable blasting assessments. Methods such as Structure-from-Motion (SfM) photogrammetry enable the creation of detailed spatial representations of tunnel faces post-blasting, allowing for comprehensive evaluations of blasting impacts. Additionally, recent developments in point cloud data processing and noise reduction have improved the clarity and accuracy of 3D models, supporting safer and more precise maintenance strategies [2]. Table 1 summarizes these and other significant research advancements in the field of tunnel blasting effect evaluation, illustrating the evolution and sophistication of methodologies aimed at enhancing our understanding of blasting impacts. These advancements reflect a concerted effort to develop more precise, reliable, and efficient methods for assessing half porosity and other critical parameters. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multicolumn{1}{c}{**No. **} & \multicolumn{1}{c}{**Year**} & \multicolumn{1}{c}{**Author(s)**} & \multicolumn{1}{c}{**Research Content**} & \multicolumn{1}{c}{**Research Findings**} & \multicolumn{1}{c}{**Literatures**} \\ \hline \multirow{4}{*}{1} & \multirow{4}{*}{1979} & \multirow{4}{*}{[PERSON]} & This study utilized finite element analysis (FEA) to examine the effects of different blast hole patterns on rock damage, aiming to optimize blasting parameters for tunnel construction. & The findings established a foundational understanding of how blast hole arrangement impacts rock integrity, paving the way for more effective blasting designs in tunnel projects. & The findings established a foundational understanding of how blast hole arrangement impacts rock integrity, paving the way for more effective blasting designs in tunnel projects. & The foundational understanding of how blast hole arrangement impacts rock integrity, paving the way for more effective blasting designs in tunnel projects.