How Do I Choose the Best Treatment for Piles?

Short pile treatment refers to the comprehensive treatment of the foundation using a combination of rigid piles and rigid, semi-rigid or flexible short piles.

1. Preparation for construction

Level the site, remove ground debris and debris, and tamp it. 2.Measurement

The total station is staked out, and the pile is buried (requires the pile to be buried with concrete to avoid being disturbed), in order to check the pile position during the excavation process and determine the center position of the pile.

3, orifice waterproof

Set up drainage sluices and drainage ditches around the orifices, and do a good job of preventing and draining the ground surface. The depth of the drainage sluice should be 30cm below the ground, and the height of the sluice shovel should be controlled at 50cm. Into the hole, prepare a tarpaulin, and cover it in time when it rains.

4.Pile hole excavation

Excavation is performed layer by layer with a pick and a shovel from top to bottom. The digging sequence is to dig the middle first and then the perimeter, and control the cross-sectional size according to the design pile diameter plus 20 cm. The soil excavated in the hole is loaded into a bucket, and the dregs are transported vertically to the ground by using lifting equipment, piled up to a designated place or directly cleaned out of the construction site to prevent environmental pollution. Note that during the digging process, it is not necessary to trim the hole wall to a smooth surface. The hole wall must be slightly uneven to increase the friction of the pile.

During the excavation process, please arrange a full-time safety officer to monitor the construction on site. The technicians measure the diameter and verticality of the pile hole at any time, and find out problems and rectify in time to avoid error accumulation.

Permissible deviations and inspection methods

Serial number	project	Allowable deviation	Testing method
1	Top position	50mm	Measurement check
2	Hole center	50mm
3	Inclination	0.5%

5.Pile concrete treatment

Dig to the short pile, remove the surface scum, cut out the fresh concrete surface, and reinforce the steel bars. The steel joints should not be on the same section, and the distance between the top and bottom should be 35d, and not less than 50cm. The excavated steel bars and acoustic tubes are cleaned to remove surface mud and dirt. After removing the main reinforcement of the cage, calculate the length of the cage to be connected to ensure the length of the reinforcement in the platform after the overlap. The upper reinforcement cage of the pile is prepared in the rebar yard. The overlap of the reinforcement can be welded by single-sided or side bars. , The weld is full and smooth, the welding length is not less than 10d, the height is greater than or equal to 0.3d, not less than 4mm, the width is greater than or equal to 0.7d, and not less than 8mm, during the welding process, the perpendicularity of the reinforcing cage should be ensured not more than 1%, And can guarantee the requirements of the protective layer. The butt joint of the acoustic tube should be carried out at the same time as the overlap of the reinforced cage. The principle of the overlap is that the verticality meets the requirements. The weld at the joint is full and does not leak.

6. Treatment of water in the hole during digging

If the amount of water seepage inside the hole is small, manual iron buckets can be used to transport it out of the hole; if the amount of water seepage inside the hole is large, the height of the excavation should be shortened to prevent erosion of the hole wall and timely Protect the wall, and use a submersible pump to pump water out of the hole.

7, piling concrete pouring

After the concrete surface at the short pile is cleaned, the pile foundation template is supported according to the height of the supplementary pile, and after the site supervision and acceptance, the concrete with the same grade as the original pile foundation concrete is poured. After the pouring is completed, the concrete is cured and the surface is covered with geotextile to keep the concrete surface moist. ^[1]

The tools used in the construction mainly include high-pressure water guns, air compressors, air picks, wire hammers, 50 plug-in vibrators, electric welding machines, cotton yarn, and round-head short-handle shovel.

1.Drill holes

Mechanical excavation to 90cm below the height of the pile top was changed to manual digging, the depth of the hole was to the top of the cast-in-place concrete pile, and the diameter of the hole was 120cm for the concrete retaining wall.

2. Broken pile head concrete

Manually excavate the top of the cast-in-situ concrete pile to remove the concrete at the pile head. After the pile head is broken, there is no pinch and loose concrete on the concrete surface, and the concrete block in the hole is cleared out.

3. Reinforcement cage extension

Reinforcement cage main bar diameter 20 is welded by double-sided overlap welding, and the weld length is 5d.

4. Base concrete treatment

Clean the surface of the reinforced concrete, clean the surface of the reinforced steel, clean the small concrete and sand particles on the concrete surface, rinse with a high-pressure water gun, and clean the surface water and fine stone powder with cotton yarn.

5.Poured concrete

C40 concrete is adopted for the design of pile-receiving concrete, and the slump is 180-220mm. Layered irrigation, 30cm per layer, using insert vibrators, the upper concrete is vibrated and inserted into the lower concrete 5-10cm, the concrete surface elevation should be 2-5cm higher than the design pile top elevation when vibrating, the platform construction will cut the surface . ^[1]

1. The measured mid-point deviation of the staked out pile position should be protected and marked in time.

2. The allowable deviation of the guard line cross is less than 2mm. Prevent artificial or mechanical damage to the pile guard.

3. Welding seams of steel bars are full and no slag. The number of welded joints of reinforcing bars of the same section is less than 50%. It is strictly forbidden to burn the main tendon during welding. The stirrups are banded, and the allowable deviation of the spacing between the stirrups is (-20, +0) mm. The deviation of the center point of the concrete retaining wall is less than + 10mm. ^[1]

Under the premise of the effective operation of the original quality assurance system and quality assurance measures of the project department, the process control of the pile foundation construction process is further clarified, refined, and implemented.

1. On the premise of ensuring the operation of the quality assurance system, strengthen the self-inspection system, and the quality inspectors and technicians supervise and guide the whole process of pile foundation pouring.

2. Establish and improve the construction instructions and technical disclosure system for bored piles.

3. Strengthen technical knowledge, replace construction personnel, provide pre-post education and training for pile foundation construction personnel, so that they can grasp the correct method and sequence, and clarify construction precautions.

4. Provide technical training to on-site technicians, strengthen the control of on-site quality, strengthen the training and learning of construction management personnel and safety personnel at all levels, and carefully study technical specifications and quality standards. The project department will periodically Carry out centralized training and learning at different levels to further improve the quality of business, so that it can better implement the norms and standards during the construction process, perform its duties, improve the quality management level, and control the quality.

5. Establish a quality assurance system based on the project department's responsibility system. There are full-time quality inspection engineers under the project department, and each team has a part-time quality inspector to form a secondary quality management network to strictly control quality.

6. In order to ensure the effective operation of the system, Wang Qin, a full-time quality inspector, is assigned to take special responsibility for the quality of pile foundation construction. At the same time, members of the quality management team of the project department conduct regular or irregular inspections and supervision of the quality of the construction site, and deal with problems in a timely manner And rectification, and verify the results of rectification.

7. Strengthen the on-site construction management. During the construction process, operators must not be replaced at will. If there is any replacement, training must be qualified before the on-site construction.

8. The project department regularly conducts comprehensive inspections of the entire line of projects, strengthens process control, identifies problems and rectifies within a time limit, and conducts quality competitions for all construction operation groups across the line, with both rewards and penalties. ^[2]