Pakistan MOHMAND Hydropower Self-Drilling Pipe Roofing System
Project Background
The MOHMAND Hydropower Project is located on the Swat River, approximately 48 km north of Peshawar in northwestern Pakistan. It is a long-anticipated national project for the government and people of Pakistan. The project is of great significance in reducing flood disasters, improving food security, alleviating power shortages, and promoting Pakistan’s social and economic development.
Challenges
The dam foundation and surrounding rock inside the tunnels of the MOHMAND hydropower project mainly consist of strongly weathered formations such as sandy soil, gravel, and alluvial sand. Borehole collapse could easily occur after drilling, making the conventional construction method of drilling first and then inserting rebar anchor bolts impractical.
In addition, the casing drilling method had relatively low construction efficiency and required a longer construction period, which could not meet the project schedule requirements.
Solution
Based on the complex geological conditions and project delivery schedule, the project ultimately adopted R32N × 4 m hot-dip galvanized self-drilling hollow anchor bolts combined with cross alloy drill bits with an outer diameter of 51 mm. Each borehole was drilled to a depth of 8 m, and every two anchor bolts were connected and extended using hot-dip galvanized couplers.
Construction Process:
Material preparation → Drilling rig positioning → Connecting anchor rod and drill bit → Connecting drilling rig for drilling → Disconnecting drilling rig from anchor rod → Installing coupler and anchor rod → Repeating drilling until reaching design depth → Grouting
Results
The self-drilling hollow anchor bolt system successfully solved the support challenges in collapse-prone formations. Integrating drilling, grouting, and anchoring into one process, the self-drilling hollow anchor bolt significantly shortened the construction period and reduced overall costs.
The drilling time for each borehole was approximately 16–30 minutes, achieving high construction efficiency. Compared with casing drilling construction, the self-drilling hollow grouting anchor bolt system reduced costs by approximately 20–30%.
Customer Feedback
The customer highly recognized the performance of Sinorock self-drilling anchor bolts in complex geological conditions. The system effectively controlled borehole collapse issues and ensured smooth project progress. With its efficient installation process and reliable support performance, the self-drilling pipe roofing solution significantly improved construction efficiency and met the project schedule requirements.
