HDL-180D1 Case Study
　　Location (Province): Guangdong Province
　　Location (City): Nanxiong City
　　Drill Rig Model: HDL-180D1
　　Drilling Tool Configuration: 146 casing + 76 drill pipe
　　Construction Technique: Casing + drill pipe dual-pipe drilling
　　Stratum Conditions: 1–2 m clay layer, 3–4 m sand-gravel layer, 5–12 m fully weathered red sandstone
　　Construction Angle (°): 90
　　Hole Diameter (mm): 150
　　Hole Depth (m): 11.5
　　Construction Efficiency (h): 0.5
　　Pure Drilling Time (h): 0.25
　　Pure Tool Disassembly Time (h): 0.15
　　Construction Technique Information:
　　1. Adjust the machine and align the hole position.
　　2. Drill the two connected casings directly through the clay layer without turning on the water pump, then use percussion drilling to pass through the gravel layer.
　　3. Use the drill pipe with the water pump on, and rotary-percussion drill to the required hole depth of 11.5 meters.
　　4. Remove the drill pipe.
　　5. Move the machine backward and lower the anchor rod using the winch and crown block.
　　6. Move the machine forward, clamp the casing with the gripper, slide and lift the feed frame to raise the casing to a position where the casing joint connects with the casing without interfering with the anchor rod, then pull out the casing with the power head.
　　Advantages of Top-Drive Drill Rig Construction:
　　1. High efficiency: a new operator can complete one pile in half an hour.
　　2. Low energy consumption: no high-power air compressor is required.
　　3. Good grouting effect: construction adjacent to grouted areas will not cause cross-hole leakage.
　　4. Good working environment for workers: water is used for slag discharge, so workers do not have to endure dust. The client and design institute relatively recognize the top-drive drill rig construction technique.