According to the layout plan, set out the pile, determine the elevation datum point, draw a circle with the pile center as the center, the pile body+wall thickness as the radius, and sprinkle lime line as the excavation line of the pile hole. After the pile alignment is determined, it shall be rechecked by relevant departments, and excavation shall be carried out after the pre-inspection procedures are completed.

2, the excavation of the first section pile hole earthwork

During construction, the periphery of the middle soil direction should be expanded first, and the section size of the pile hole should be controlled, and the height of each section should be 0.9-1.2m. ..

3, support wall steel binding, template installation

After the hole is formed, a retaining wall needs to be set up. It is suggested that it is best to use cast-in-place reinforced concrete retaining wall and then combine it with earth wall, so that the stability and integrity are better and the force is more uniform.

When installing retaining wall formwork, fixtures and fasteners should be used to fix it, or circular arcs should be set at the top and bottom of each formwork, and the inner steel ring made of channel steel should be used as internal support to prevent the deformation of the internal formwork.

4, pouring concrete retaining wall

During construction, it is better to pour concrete immediately after each section is completed, and its slump should be controlled within 100 cm, and it should be vibrated and compacted. If there is water seepage, it can be accelerated.

5, check the pile (center) axis and elevation.

After the retaining wall construction is completed, it is necessary to check whether the axis and elevation of the pile location are normal, and then repair it. The hole depth should be measured one by one based on the datum point.

6, erection of vertical transport frame

After the pile hole is drilled, a vertical transportation support should be erected, and the support should be stable.

7, install electric hoist or hoist

Install pulleys, electric hoists or cranes on the transport frame. Set a soft ladder in the hole to facilitate workers to get up and down, and then install electric hoist, hanging cage and other equipment.

8. Install buckets, pumps or ventilators.

Install tools such as bucket and bottom hole lighting as required. If the amount of underground water is not large, it can be transported out in buckets. If the amount of underground water seepage is large, it can be pumped by water pump to keep the water level stable.

9. Earthwork Excavation of Pile Hole in the Second Section

Starting from the second quarter, use lifting equipment to move soil. After digging to the design depth, check the radian and perpendicularity of the hole wall with a brace, and then trim the hole wall.

10, the second quarter retaining wall steel binding, template installation

Fasten the reinforcement of the retaining wall in the second section as required, and then install the formwork. Note that the retaining wall formwork can be reused.

1 1. pour the second section of concrete.

When pouring concrete, it should be tamped. If there is water seepage in the soil layer, the concrete can be quickly hardened with an accelerator. In addition, when pouring, the height of each retaining wall should be controlled within 30-50 cm, and the concrete should be poured as it is dug.

12, check the pile centerline and elevation.

According to the orifice positioning line, check the center line and elevation of the pile and adjust it section by section.

13, step by step,

When the hole depth reaches the design depth, the virtual soil should be removed, and then the soil quality should be checked. Note that the pile bottom must be on the bearing layer.

14. Dig and enlarge the bottom.

There are two kinds of pile bottom, one is enlarged and the other is not enlarged. When expanding the bottom, it is necessary to dig a pile tube at the bottom, and then cut the soil from top to bottom according to the size and shape of the bottom. In order to prevent the earth from collapsing when expanding the bottom, it is necessary to excavate at intervals, and it is best to leave 4-6 soil ribs as support, and then pour concrete after excavation.

15, inspection and acceptance

After the above steps are completed, the construction records should be made, and the acceptance procedures should be handled, waiting for the relevant units to conduct acceptance appraisal.

16, hoisting reinforcing cage

When hoisting the reinforcing cage, aim at the hole position, and then lower it slowly to avoid collision with the hole wall. When it is placed in the design position, it should be fixed immediately. When two reinforcing cages need to be connected, they should be connected by double-sided welding.

17, pouring pile concrete

When pouring, stones with particle size less than 5 cm should be used, and the slump should be controlled at 8- 10 cm. In addition, when pouring concrete, it should be done continuously and vibrated by layers. Generally, the top surface of the enlarged bottom is poured first, and then the upper part is poured until the pouring is finished.

What problems should be paid attention to in the construction process:

1. Technical safety disclosure shall be made before construction, and safety measures shall be taken according to the construction plan.

2. Check whether the mechanical equipment is normal before operation.

3. The soil dug out from the hole should arrive at the designated place and should not be piled up at the orifice.

4, when pouring concrete, vibrating while pouring.