Key points of quality control in construction supervision of pile foundation engineering?

The following is the related content of quality control points of pile foundation engineering construction supervision brought by Zhong Da Consulting for your reference.

1. Project overview

The total construction area of this project is 62,000 square meters, and residential buildings mainly include underground garages and six residential buildings, with the lowest 10 floor underground and the highest 16 floor above ground. The foundation engineering adopts static PHC-AB pipe pile, with concrete strength of C80, pile diameter of 500mm (wall thickness of 125mm), effective pile length of 12m, 18m and 22m respectively, pile tip type of A (cross), and the corresponding standard value of vertical ultimate bearing capacity of single pile is 3300KN.

According to the requirements of the design institute, the final pressure of pile sinking is controlled according to the following two conditions: ① When the elevation of pile top has reached the design elevation, but the loading pressure value does not meet the design requirements, it is controlled according to the elevation; (2) If the loading pressure value has reached the design value, but the pile top elevation has not reached the design elevation, it should be controlled according to the pressure value, and the loading pressure value should be ≥5200 kn. Before the pressurization is terminated, it shall be recompressed for three times (full loading-unloading-reloading, repeated for three times), and the loading pressure value of each stroke of the static pressure pile driver shall be recorded, and the actual elevation of the pile top shall be measured.

2. Key points and methods of supervision quality control

Static pressure pile sinking construction was used earlier in coastal cities, but it was only used and popularized in northwest China in recent years. The construction technology and management level are uneven, which brings certain difficulties to on-site supervision. The quality control described in this paper is mainly aimed at the quality control of static pressure pile construction supervision and the content closely related to this process. The construction procedure of static pressure pile sinking is as follows:

Measuring and positioning-checking pile position-pile driver in place-hanging pile and inserting pile-aligning and straightening pile body-static pressure piling-pile connection-static pressure piling-pile delivery-final piling.

According to the static pressure pile construction process engineering, the key points of supervision quality control should be divided into three stages: before, during and after.

2. 1 Prior control:

(1) Before the project starts, carefully review the construction organization design of the construction unit. The content should be complete, in line with the relevant design requirements and the actual situation of engineering construction.

(2) Supervise the construction unit to establish a quality, technology and safety guarantee system, and all kinds of personnel shall be in place as required and have corresponding qualifications.

(3) Require the construction unit to be familiar with the construction drawings and geological data carefully, and the supervision unit shall take the lead in organizing relevant units to conduct the blue prints.the design, and record relevant issues and treatment methods in detail in the minutes of the blue prints.the design.

(4) Because the pile foundation requires high accuracy of positioning and setting-out dimensions, it is necessary to carefully check the indoor calculation results (data coordinates of each pile position) measured by the construction unit, and conduct on-site positioning and setting-out after review by the supervisor. Only after the construction unit has passed the self-inspection and is approved by the supervisor can it enter the next working procedure.

(5) Number the pile position of each engineering pile on the construction drawing to avoid duplicate or missing numbers, so as to master and understand the construction situation of each pile and check whether there are any missing piles.

(6) The pre-stressed pipe piles entering the site must have the manufacturer's certificate and the specific quantity, which shall be reported to the supervisor for confirmation, and can only be used after passing the appearance inspection. The unqualified pipe piles are strictly prohibited. At the same time, it should be noted that the on-site stacking shall not exceed seven floors.

(7) Prepare the detailed rules for the implementation of the construction supervision of static pressure pile sinking and the side-by-side plan.

Flatness is the key to the quality of pile pressing, which must be highly valued. First of all, the site should be flat and have enough bearing capacity to ensure the stability and verticality of the static pile driver. Secondly, the verticality deviation during pile insertion shall not exceed 0.5%. Finally, when sinking piles, use theodolite erected in two vertical directions to adjust, and the adjusted verticality is within the allowable value of the specification before the pile sinking construction in the first section can be carried out. During pile sinking, the change of pile footage should be observed at any time. If there are obstacles in the geological layer and the pile body deviates, it should be straightened gradually once or twice.

(5) Pile extension:

(1) Pile extension shall be carried out at about 1m from the ground. At the same time, it is necessary to ensure that the upper and lower piles are straight and misaligned.