Selection of monitoring poles and key points in foundation construction
From height, wall thickness, cantilever arm to foundation size and embedded parts, the engineering basis for pole selection and common safety hazards are explained.
Pole height selection
| Height | Applicable | Instructions |
|---|---|---|
| 3.0～3.5 meters | Pedestrian passages in the community and inside the park | Easy to maintain and not easy to block |
| 4.0～6.0 meters | Park roads and parking lots | Most commonly used sections |
| 6.0～8.0 meters | Urban roads and bayonet gates | Need to consider hoisting and maintenance |
| More than 8 meters | Squares and large perimeters | Require special structural calculations |
Key parameters
- Wall thickness: Commonly used are 3~4mm (low pole) or 4~6mm (high pole). Insufficient wall thickness will cause significant shaking in strong winds. Leading to screen jitter and fatigue breakage.
- Material: Hot-dip galvanized steel pipe is the most common. It is recommended to use 304/316 stainless steel or strengthen anti-corrosion in coastal or chemical industry areas.
- Arm length: Generally 0.5~2.0 meters. The longer the cantilever arm, the higher the requirements for foundation and wall thickness.
- Wind load: Check based on the local basic wind pressure once in 50 years. Coastal and typhoon areas should focus on review.
- Hand holes and cable holes: Hand holes are reserved for inspection, and there is room for internal cables.
Basic construction
- Foundation size: related to pole height, cantilever arm and soil quality. The common 6-meter pole is 600×600×800mm (length×width×depth), Weak foundations need to be reinforced or piled.
- Embedded parts: Use anchor bolts + flange connections, and the bolt specifications and burial depths are implemented as designed. Check the positioning dimensions before pouring.
- Concrete: C25/C30 is commonly used, and it must be cured for no less than 7 days after pouring before pole erection.
- Grounding: The ground electrode is pre-embedded in the foundation, and the ground resistance meets the design requirements.
- Drainage: The top surface of the foundation should be 100~150mm higher than the surrounding ground to avoid water accumulation.
Common security risks
- The basic size is reduced based on experience, and the pole tilts or topples after strong winds.
- The position deviation of the embedded bolts is too large and they must be forcibly bent or cut on site.
- The wiring holes are not sealed waterproofly, and rainwater enters the foundation and equipment box along the pipes.
- The equipment box is not fixed or has poor heat dissipation. High temperatures in summer cause the equipment to restart frequently.
- If grounding is not done or the grounding resistance is unqualified, equipment will be damaged in batches during thunderstorms.
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