Pile Foundation Engineering
Material Requirements
Precast piles must have factory certification and inspection reports. All incoming components should be clearly labeled and free from visible defects. Their identification marks, model specifications, and appearance quality must comply with design requirements.
Construction Requirements
1. Reinforcement Cage Production and Storage
-
The production and storage area for reinforcement cages must be concrete-hardened.
-
Finished reinforcement cages should be stacked neatly to prevent mud contamination.
2. Precast Pile Construction
(1) Site Preparation
-
If the ground bearing capacity is insufficient for machinery operation, methods such as soil replacement, preloading, or surface reinforcement should be applied.
-
For static pressure pile sinking, the ground bearing capacity must be ≥1.2 times the machine’s grounding pressure.
-
The site must be leveled and free of water before pile rig installation.
(2) Equipment Leveling
-
After positioning, use the pile rig’s vertical control system or dual-directional leveling instruments for adjustment.
(3) Verticality Monitoring
-
During pile sinking, a theodolite must monitor pile verticality.
3. Pile Head Treatment
(1) Cast-in-Place Piles
-
Before breaking, mark a control line 30cm above the cushion elevation.
-
Mechanically remove concrete above the line; below it, use light manual tools to expose dense concrete.
(2) Precast Piles
-
Cut with professional equipment—avoid sledgehammer use.
-
Clean the inner wall, then fill with concrete flush with the pile top.
4. Pile Head Embedment & Rebar Anchoring
(1) Embedment Depth
-
Pile embedment into the cap must meet design specs; clean the side mud thoroughly.
(2) Low Pile Head Adjustment
-
Shape the pile side into a “wok bottom,” plaster with mortar, ensuring >5cm protrusion.
(3) Rebar Anchoring
-
Straighten longitudinal rebars; weld extensions if the anchorage length is insufficient.
-
For prestressed piles, anchor bars should incline at 75° (see Fig. 3-8).
5. Site Marking
-
Mark pile centers, deviations, and structural member positions on the cushion layer.
Inspection
-
Conduct real-time checks on materials, fabrication, pile formation, and head treatment.
-
Post-construction, randomly inspect 3 points for pile heads and markings—results must comply.
Excavation Engineering
Construction Requirements
1. Retaining Pile Head Treatment & Anchoring
-
Before capping beam rebar binding, level and clean pile/wall tops.
-
Ensure embedment depth and rebar anchorage meet design criteria.
2. Concrete Strut Formwork
-
Maintain precise formwork alignment and rigidity.
3. Strut Alignment & Elevation Control
(1) Axis Control
-
Align struts via string lines; max deviation: 10mm.
(2) Elevation Marking
-
Cap beams/struts must match design elevations. Weld 4 m-spaced level markers and label clearly.
4. Structure Protection
-
Prevent excavation machinery from damaging supports.
-
Cover critical zones (e.g., piles, dewatering wells) with soil/steel plates and mark signs.
Excavation Monitoring
1. Monitoring Points
-
Quantity, placement, and methods must match approved plans.
-
Use standard sensors, fix them securely, and label each point.
2. Reference Benchmarks
-
Install on stable ground using ≥C20 concrete (Fig. 4-5).
3. Crack Gauges
-
Fix with 40mm expansion screws on sides (Fig. 4-6).
4. Cap Beam Displacement Points
-
Drill holes (5cm wider than sensors) and backfill with M7.5 mortar (Fig. 4-7).
5. Deep Displacement Sensors
-
Use 10 cm-wider boreholes, backfilled with compact sand; protect tube mouths (Fig. 4-8).
6. Axial Force Sensors
-
Bind with wire, sheath cables, and extend >500mm beyond concrete with protective casings.
7. Public Display
-
Post monitoring summaries and conclusions onsite (Fig. 4-9).
Inspection
-
Supervise materials, construction, and monitoring in real time.
-
Sample-test 3 random points for pile integrity, markers, and strut appearance post-completion.
