1, pile position measurement and pile position positioning are verified and signed by the survey engineer of the general manager's office.
2. Material inspection: The required materials and concrete mixture ratio shall be examined and approved by the material engineer in the director's office.
3. The application for commencement shall be approved by the structural engineer of the director's office.
4, all kinds of machines and tools are safe and reliable, and the construction environment is up to standard.
5. The construction site must be equipped with generators and high-pressure mud pumps to prevent accidents.
Second, the examination and approval of the commencement report
Seven days before the commencement of construction, the construction party shall submit the application report for commencement, and the construction can only be started after the approval of the supervision engineer.
1, the use of machinery:
(1) Check whether the machinery is safe and reliable, and stop using the machinery with poor performance to avoid quality accidents and personnel accidents caused by mechanical failure.
(2) Check whether the selection of machinery meets the specification requirements. According to the different types of machinery in geological conditions, the supervision engineer approves the types of machinery used according to the requirements of the specification, and achieves the best results.
(3) Choose different construction methods according to different types of machinery. Check mud consistency.
2. The construction scheme of important sub-items of pile foundation must be approved by the director's office.
3. The qualification of construction personnel meets the specification requirements (technicians hold relevant certificates, electricians hold relevant certificates and welders hold relevant certificates).
Three. Examination and approval of important sub-item construction scheme of pile foundation: (attached with flow chart)
1, the examination and approval of the process flow is mainly about whether the examination and approval is rigorous, whether there is plagiarism or misappropriation of other engineering schemes, etc. , and each technological process must be strictly supervised or on standby during implementation;
2, the organization's approval plan must explain the specific personnel and qualifications of the quality assurance system, and review whether they are on the job;
3. Whether the safety and environmental protection measures are reasonable;
4. Emergency measures in different situations. Due to the geological conditions and geological conditions indicated in the design, the possibility of changes is relatively high, and the probability of accidents in pile foundation construction is relatively high. Therefore, the plan must include emergency measures when problems occur, and must report the accidents in time and take corresponding measures to solve the problems. (Several common accidents and emergency measures taken)
1) Buried hole: the hole collapse caused by geological conditions and the mud mixture ratio caused by man-made do not conform to the specifications, and the hole collapse caused by mechanical failure and human disturbance must be backfilled and re-drilled. In this case, machinery and backfill should be carefully selected, and coarse soil should be used as backfill;
2) Encountering boulder: When drilling sand layer or gravel layer, it is inevitable to encounter boulder. At this time, it is advisable to stop drilling and backfill immediately. Low-grade concrete should be used for backfilling to avoid downward deviation of the lower hole. It is best to use an impact drill, re-stir the mud and drill slowly.
3) Stuck: During the construction process, the drill gets stuck due to slow speed or encountering small boulder. If the forward and reverse circulation drilling and rotary drilling can rotate slowly, then slowly lift the drill pipe as much as possible, so that the drill bit and drill pipe will be smashed with an impact drill. If the percussion drill breaks the rope, it can be hooked out with a three-claw hook. If the drill bit is buried, it can be lightly washed with a small drill bit to find out the drill tail.
4) The lower end of the conduit is too close to the bottom of the pile, which will lead to no leakage of concrete poured into the pile, and the upper and middle concrete will exert pressure on the lower part, which will block the lower concrete. After lifting the conduit, the concrete in the conduit will not leak until the conduit is lifted to a certain height. At this time, if the conduit is poured again, the mud will be trapped in the pile, and the hole needs to be cleaned again. After the concrete and mud in the hole are cleaned with a high-pressure mud pump, the pile will be poured into the conduit.
5) Broken pile: the hole suddenly collapses during pile grouting. At this time, the conduit will be pulled out of the reinforcement cage as much as possible, and the unconsolidated concrete and collapsed soil will be quickly pumped out by the high-pressure mud pump (at the same time, the wall must be protected by mud to avoid collapse and expansion). Then drill the pile core with an impact drill with a diameter less than 20cm, and then take out the steel bar for reaming.
6) In nondestructive testing, there are local mud bags outside the pile, so high-pressure flushing can be used to impact the mud bags, and then high-pressure grouting can be used to inject high-standard mortar, but this method is not suitable for piles with more mud bags outside the pile;
7) The mud bag in the pile becomes the third kind of pile, and the hole is re-formed by coring and reaming with impact drill. There is an approved scheme for the above conditions.
Four, the supervision of each working procedure, each working procedure is closely related to each other, and the mistakes of one working procedure will inevitably lead to the failure of the next working procedure. Therefore, it is necessary to supervise carefully and record carefully to ensure the engineering quality.
Before supervision, supervisors must study the drawings carefully, be familiar with the specifications, explain the quality standards and allowable errors of each working procedure in time at the scene, and check whether each working procedure meets the standards at any time;
Five, the specification requirements involved in pile foundation construction
(1) Measure and locate the pile position. According to the relevant data, the construction unit can be determined after being rechecked by the survey engineer of the director's office;
(2) Setting of gasket
1, the inner diameter of the casing should be 200mm ~ 400mm；;
2. The vertical line in the center of the pile casing should coincide with the center line of the pile. Unless otherwise specified in the design, the allowable error of the plane is 50 mm, and the inclination of the vertical line is not more than 65438 0%;
3. The casing height should be 0.3m higher than the ground and not less than 1m higher than the pile top. When there is confined water in the drilling rig, it should be more than 2.0m higher than the stable confined water level;
4. The buried depth of the pile casing shall be determined according to the design requirements or the hydrogeological conditions of the pile location. Generally, the buried depth is 2~4m, which should be deepened under special circumstances to ensure the smooth drilling and concrete pouring.
5. The riverbed with scouring influence should sink below the local scouring line not less than1.0 ~1.5m;
6. The connection of the gasket requires that there are no protrusions in the barrel, and it should be able to resist tension, pressure and water leakage;
7, liners positioning, dry place can be measured positioning, water can rely on the guide frame positioning.