# BIM-Based Optimization of Drilling Angle and Hole Position of Outside Corner Anchor Rods
## 1 Introduction
applied BIM technology to the construction of the Haikou North Tower foundation pit project [24], while in 2021, [PERSON] et al. employed BIM technology in a complex foundation pit project located in a busy urban area [25]. Both applications involved detailed design, 4D simulation-based progress tracking during construction, and the use of visualization technology, ultimately resulting in significant time and cost savings in these projects. These applications ensured construction quality and safety, reduced environmental impact, minimized disruption to the lives of nearby residents, and notable economic and social benefits. \begin{table}
\begin{tabular}{c c c c} \hline
**Project Name** & **Number of Floors** & **Total Height (m)** & **Underground Excavation Depth (m)** \\ \hline Capital Mansion & 50 & 183.00 & \(-\)23.50 \\ \hline Main Building of Xinhua News Agency & 26 & 127.00 & \(-\)19.60 \\ \hline China International Trust Building & 28 & 101.60 & \(-\)13.50 \\ \hline Main Building of Beijing Library & 19 & 64.00 & \(-\)11.90 \\ \hline Beijing New Century Hotel & 35 & 109.00 & \(-\)10.80\(--\)14.00 \\ \hline Beijing International Hotel & 31 & 104.40 & \(-\)14.30 \\ \hline China Zun Building & 108 & 528.00 & \(-\)38.00 \\ \hline Jingxi Hotel & 29 & 96.60 & \(-\)11.00 \\ \hline XiyuanHotel & 22 & 71.80 & \(-\)11.12 \\ \hline Beijing Yu Yang Hotel & 28 & 96.60 & \(-\)11.60 \\ \hline Hotel New Otani Chang Fu Gong & 25 & 90.00 & \(-\)14.33 \\ \hline China Patent Office & 25 & 76.30 & \(-\)15.00 \\ \hline \end{tabular}
\end{table} 
Table 1: Situation table of some high-rise and super high-rise buildings in Beijing. BIM technology is now widely utilized in foundation pit projects, providing features such as visualization, simulation, and easy optimization and improvement. Compared with traditional methods, BIM technology can save a lot of time and cost [26; 27]. Applying it to concealed engineering can solve the problems that exist during design and reduce unpredictable construction risks [28; 29; 30; 31]. In 2015, [PERSON] et al. summarized the application of BIM technology in deep foundation pit engineering, realizing the collision inspection of the support structure [32]. In 2017, [PERSON] used Navisworks collision detection software to conduct collision detection on the anchor rod model in Revit. He verified the accuracy of the software via manual calculations. After that, he adjusted the anchor rod according to the \"Building Technical Specification of Protection of Foundation Pit\" manually and rechecked the stability of the anchor rod [33]. In 2018, [PERSON] et al. used BIM technology to manually adjust the collided anchor rods after completing the collision detection [34]. In 2023, [PERSON] et al. developed a set of Revit external family systems related to foundation pit engineering. He used Revit's collision check function to conduct collision detection on the model and solved the collision problem by adjusting the tilt angle of the family instance [29]. It can be seen that using BIM technology to solve the problem of anchor rod collision is a common method [35; 36; 37]. However, manual collision detection and anchor rod adjustment are still challenging due to the following factors:  
1. When facing a large number of anchor rods, adjustments cannot be made quickly, thereby consuming a lot of time and manpower as well as delaying working hours;
2. The accuracy is insufficient, and after adjustment, the angle and hole position may not meet the specifications, or collisions may occur between anchor rods that were originally collision-free;
3. The visualization is insufficient, and whether a collision occurs can be observed in the 3D model without intuitive data display. This paper focuses on the application of BIM technology in anchor rod support, and it proposes a method that can accurately and quickly optimize the drilling angle and the hole position of anchor rods at the external angle of the foundation pit by integrating BIM and visual programming software.