the control points

⑴ control orifice positioning error
In the above settings Secant Pile Top Construction guide wall (This project uses reinforced concrete guide wall, can also be recycled steel guide wall), the guide wall set positioning hole, the diameter should be bigger than the pile diameter 20 ~ 40mm. Rig in place, check the first one cannula inserted into the positioning hole and require the construction unit is adjusted so that the positioning around the casing to maintain a uniform gap between the holes.
⑵ urge the construction unit controls the vertical piles
According to design requirements, pile vertical deviation of not more than 3 ‰. Secant pile in order to ensure a sufficient thickness at the bottom of the amount of bite, in addition to its strict control orifice positioning errors, but also its vertical strictly controlled.
Pore-forming process to control the verticality of the pile, you must grasp the following three aspects of the work:
① straight cannula degree examination and correction
Secant piles on flat ground before casing straight degree examination and correction, dental machine first check and correct single casing straight degrees, and then will follow the entire length of the pile sleeve configured to connect together for the entire root sheath tube (15 ~ 25m) of straight deviation should be less than 10mm. Detection method: measured on the ground emit two mutually parallel lines, the sleeve is placed between the two lines, and a line for testing the hammer and ruler.
② pile into the hole during the vertical monitoring and inspection
a ground monitoring: ground select two mutually perpendicular directions using the line hammer monitoring above-ground parts of the vertical casing, correct any deviations found. This test in each pile into the hole process should adhere to from beginning to end, can not be interrupted.
b check: After installing each section of casing pressure casing before the next section, we must stop to use the "test loop" in the hole verticality checks, failed when the need for correction, until qualified to the next section casing construction.
③ correction
Pore-forming process, such as found in vertical deviation is too large, the importance of timely corrective adjustments require the construction unit, correcting There are three common methods:
a cylinder with a rig for correction: If the deviation is not greater than or buried casing is not deep (5m less), you can directly use the rig two jacking cylinders and two sliding vertical cylinder adjustment sleeve, you can achieve the purpose of correcting .
b pile Correction: If A pile buried 5m large offset occurs below, you can first use drill cylinder direct correction, such as below standard, can be filled with sand to the casing or clay, while filling side uprooted casing, until enhance the sleeve to the last pass the inspection place, and then straighten casing, check and re-qualified under vertical pressure.
c correction: B Pile A pile corrective method is basically the same, the difference is that the casing can not be filled while filling the same with the A pile of concrete, or they may be left in the soil between piles mezzanine, thus affecting the row Pile waterproof effect.
⑶ ultra-retarding Concrete Construction Quality Control
A pile of concrete retarding time should be based on time to determine the pile into the pile, pile into the pile time and geological conditions of the construction site, pile length, pile diameter and drilling capacity factors. According to bite Piles, A pile initial setting time of T = 3t + K + Q;
Where: T - A pile of concrete retarding time t - the time required for single pile into the pile
K - reserve time, usually 1.0t Q - Night downtime
A pile acrylic resin teeth general preliminary control initial setting time of 60h, the construction in the future be adjusted according to the scene.
⑷ occlusal thickness determination
Engagement between adjacent pile thickness d to select based on length of pile, pile shorter occlusal thickness is smaller, thicker pile longer bite, are calculated as follows:
2 (kl + q) ≤ d - 50mm (which is to ensure a minimum pile occlusal thickness not less than 50mm)
Where: l - pile length d - Secant Pile design occlusal thickness
k - pile verticality q - orifice positioning error tolerance