Safety requirements for construction of the hottes

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Safety requirements for the construction of manually dug cast-in-place piles

I. General safety requirements

l manually dug cast-in-place piles (hereinafter referred to as dug piles) are applicable to projects with good engineering geological and hydrogeological conditions, shallow bearing stratum and large single pile bearing capacity. If there is no reliable technology and safety measures. Digging pile construction shall not be carried out in sandy soil with high groundwater level (especially in the presence of confined water) and muddy soil layer with large thickness

2. Generally, the hole depth of dug pile should not exceed 40m. When the pile length L ≤ 8m, the diameter of the pile body (excluding the retaining wall, the same below) should not be less than 0.8m; When the pile length is 8m < L ≤ 15m, the diameter of the pile body should not be less than 1.0m; When the pile length is 15m < L ≤ 20m, the diameter of the pile body should not be less than 1.2m; When the pile length exceeds 20m, the diameter of the pile body should be appropriately increased. When the clear distance between piles is less than 4.5m, interval excavation must be adopted. The minimum net construction distance of row pile skip excavation shall not be less than 4.5m

3. the strength grade of the concrete for the retaining wall of the dug pile shall not be lower than C15. The height of each section of the retaining wall depends on the soil quality, which can generally be 0 m。

4. When digging piles are used in karst areas or in rock layers with uneven weathering, interlayers, soft and hard deformation, but unfortunately, it is advisable to drill an exploration borehole at each pile or column position. The drilling depth should generally reach 3 times the pile diameter below the hole bottom of the digging pile, so as to judge whether there are holes, fracture zones and weak interlayers in the bedrock within this depth range

5. For the buildings (structures) adjacent to the site, the formal test of the samples should be carried out after the relevant durometer is in the normal operation mechanism state before construction. The unit and the owner should conduct a detailed inspection, and the original cracks and special conditions of the buildings (structures) should be recorded for future reference. Reinforcement measures shall be taken in advance for adjacent houses that may be endangered by hole digging and pumping

6. Drainage ditches and water collecting wells should be set up on and around the site, and the treatment plan of mud and waste residue should be formulated. The excavation route at the construction site shall be unblocked

II. Construction safety measures

1. Workers engaged in hole digging pile operation should be healthy young men, and they can enter the construction site only after passing the health examination and safety operation training in underground, high altitude, electricity, hoisting and simple mechanical operation

2. Before the joint review of construction drawings and pile hole excavation, drilling data should be carefully studied, geological conditions should be analyzed, attention should be paid to the possible quicksand, piping, water inrush and harmful gases, and targeted safety protection measures should be developed. If there are doubts about safe construction, they should be raised with relevant units in advance

3. in order to prevent the hole wall from collapsing, a reliable construction method of supporting the hole wall should be adopted according to the pile diameter and geological conditions

4. the orifice operation platform shall form a stable system by itself to prevent it from being pulled down when the retaining wall sinks

5. All equipment, facilities, safety devices, tools, accessories and personal protective equipment at the construction site must be inspected frequently to ensure their integrity and safe use

the electric hoist and cage used must be qualified mechanical equipment, and should be equipped with automatic clamping safety device to prevent sudden power failure. Push button switches should be used for electric hoists. Before and after work, special personnel should strictly check and add enough lubricating oil every day to ensure that the switch processing process is flexible and accurate, the iron chain is undamaged, there are safety buckles and no knots, and the steel wire rope is not broken. The support frame shall be firm and stable, and its safe lifting capacity must be checked before use

6. workers must use steel ladders to get up and down the pile holes, and it is not allowed to use manual ropes to transport workers and feet. The most simple and useful way to avoid the rust of the hydraulic forming machine is to paint the press machine with anti-oxidation paint and step on the protective wall flange to get up and down the pile holes. Nylon safety rope is set on the inner wall of the pile hole and extended to the working face with the increase of the excavation depth as a backup for emergency

7. After pile hole excavation, site personnel should pay attention to the changes of the ground and buildings (structures). If the pile hole is close to the old building or dangerous building, reinforcement measures must be taken for the old building or dangerous building before construction. Strengthen the observation of water gushing in the soil layer of the hole wall, and take timely treatment measures if abnormal conditions are found

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