1. Entry control

1. The strength of the pipe pile shall reach 100% of the design value before it can be transported to the site.

2. The product qualification certificate, appearance and external dimensions shall be checked when entering the site.

(1) Appearance: no honeycomb, exposed concrete, cracks, uniform color, no cracks at the top of the pile.

(2) Shape: pile diameter ±5mm, pipe wall thickness ±5mm, pile tip center line less than 2mm, top surface flatness less than 10mm, pile top bending less than 1/1000L (L is the length of the pile).

(3) The pile body shall have the marking of pipe pile, manufacturing date and pipe pile number.

2. Site stacking

1. The two-point method is adopted when lifting the pipe pile, or the hook lifting can be used at both end plates, and the angle between the rope and the pile body is greater than 45°.

2. During loading, unloading and lifting, it should be moved horizontally. Throwing, collision and rolling are strictly prohibited.

3. The pile storage site must be flat and firm, with drainage measures.

4. The bottom layer of the pipe pile shall be set with two support points, and the support points shall be on the same horizontal plane, with a spacing of 2/3L (L is the length of the pile).

5. The pipe diameter of 400mm can be stacked for 4 layers, and the pipe diameter of 500mm and 600mm can be stacked for 3 layers. Each layer should be set with two support points.

6. Pile shall be stacked separately according to different specifications and models.

3. Pre-construction preparation work

1. The axis should be released with the introduction of national triangulation network control points, and should be verified for many times. The position of on-site axis control points should not be affected by pile sinking operation, and the number should not be less than two.

2. Check whether there are buildings near the construction site, poles and wires in the air, and pipelines underground, and take the following measures.

(1) Dig seismic ditches with a width of 0.5~0.8m and a depth according to the soil conditions and the self-supporting slope.

(2) Set up bag sand well, with diameter of 70-80㎜, spacing of 1~1.5m, depth of 10-12m.

3. Determine the order of piling according to the density of piles and the relationship with surrounding buildings.

(1) If the piles are dense and far away from the building, it is advisable to proceed from the middle to the periphery when the site is open.

(2) If the piles are dense, the site is long and narrow, and the ends are far away from the building, it is advisable to proceed from the middle to both ends.

(3) If the piles are dense and close to the building, it is advisable to start from the adjacent side of the building and proceed from near to far.

(4) According to the specifications of the pile, it is advisable to start with large and then small, long and short.

4. Check whether all parts of the pile driver are running normally and whether the connection is firm. The pressure gauge must be tested by an authoritative department before it can be used.

5. The installation site of the pile driver shall be treated according to the construction requirements. The site shall be leveled and the ground shall reach the average bearing capacity of 35kPa.

6. Check the pile position, the deviation shall not be greater than 20mm.

7. Mark the length of the pipe pile in meters.

IV. Quality control

1. Vertical deviation of pipe pile lifting and positioning shall not be greater than 0.5% when it is inserted into the ground. The verticality of the pile shall be monitored by setting up a theodolite from front and side at 90° direction with measuring instruments. It is advisable to pull out and reinsert the pile if necessary, and it is strictly prohibited to move the pile machine to correct the deviation.

2. When the pipe pile is extended, it is advisable to extend the pile head 0.5-1m above the ground.

3. When the pile is joined, the upper and lower sections of the pile should be kept straight, and the offset deviation should not be greater than 2mm.

4. Clean the joint surface and bevel when connecting. If the gap between the pile section is large, fill it with iron plate to weld firmly. The gap between the joint surface shall not be greater than 2mm.

5. During welding, start with symmetrical spot welding at points 4-6. Two certified welders shall then perform symmetrical welding. The number of welding layers must be no less than two: the first layer requires a 3.2mm diameter electrode for root pass, followed by a 4mm or 5mm diameter electrode for the second layer. After thoroughly cleaning the inner layer, proceed to the outer layer. The weld thickness should exceed the groove by 1mm, with the weld seam being full, continuous, and free from porosity, slag beads, or cracks.

6. After welding, the rest time is more than 5min, and it is strictly prohibited to use cold water cooling or welding pressure.

7. During the pile pressing process, the pressure, verticality of the pile, interval time between pile joints, connection quality and depth of pile pressing should be checked. For important projects, 10% of the welds of the pile joints should be inspected.

8. Do not weld when the temperature is lower than 0℃, rain, snow and other reliable measures are not available to ensure welding quality.

9. Each pile should be constructed continuously in one time to minimize downtime.

10. If the pile spacing is less than 3 times the pile diameter, the pile must be driven by jumping.

11. Control the elevation of the pile top, calculate the height of the pile driven according to the design elevation of the pile top, and mark it on the pile driver.

12. Protect the pile head above the ground. The cut pile should be cut with a cutting machine. It is strictly prohibited to hit or pull the cut pile with a hammer.