1. Stakeout positioning

Before the start of the project, a survey control network is established in the site according to the axis and pile position layout, and then the core points of each pile position are measured and placed according to the control network.

2. Rotary digging machine in place

The drilling rig must be stable, upright, level, and positioned. The error between the core of the drill bit and the core of the pile position should not exceed 10mm.

3. Buried protective tube

The diameter of the protective tube should be 200mm larger than the diameter of the pile hole, and the length should meet the requirement that the bottom of the protective tube enters the clay layer not less than 0.5m, the top of the protective tube is 0.3m above the ground, and the inclination of the protective tube should be controlled within 1% , The embedment deviation of the protective tube shall not exceed 30mm, and the surrounding of the protective tube shall be backfilled with clay and compacted in layers.

4. Rotary digging machine makes holes

Use modern tool rotary excavator for hole formation: After the protective tube is buried and positioned, use the SR-250 rotary excavator for drilling. The drilling rig has large torque, high speed, and high hole forming efficiency, which is suitable for drilling in the middle weathered layer. .

The drilling rig should be re-measured and positioned when it is in place, and mud wall protection should be used during the hole forming process. The mixing action of the drill bit on the soil during the drilling process is used to make the mud naturally, and the specific gravity of the mud can be adjusted according to actual needs. The specific gravity of the mud is generally controlled between 1.2 and 1.3 during the construction process. The mud is on the surface of the hole wall during the circulation process. The mud skin is formed, and the weight of the mud and the mud protect the hole wall and prevent the hole wall from collapsing.

Through hole construction, the mud wall protection effect is better, which can fully meet the needs of construction. The specific gravity of the mud can be adjusted by digging out the slag bucket and adding clean water to the hole. According to the actual construction needs, the specific gravity of the mud can be controlled above 1.3, which is conducive to drilling and the stability of the hole wall.