5 Precautions in Sensor Installation in Dynamic Pile Testing
1. The strain sensor and acceleration sensor shall be symmetrically installed in the surfaces of pile sides which are not less than 2D or 2B away from the pile top respectively; for the piles with large diameters, the distance between sensor and pile top may be reduced appropriately, but should not be less than D; the material and cross-sectional dimension of mounting surface of sensor shall be the same as that of original pile body, and the sensor shall not be installed near the position with abrupt change of cross-section;
2. The materials of mounting surface of each sensor shall be even, compact and smooth; when the mounting surface of sensor is not smooth, rub it down with an abrader;
3. The centers of strain sensor and acceleration sensor shall be on the same horizontal line; the horizontal distance between strain sensor and acceleration sensor at the same side shall not be more than 80mm;
4. The bolt hole of sensor shall be installed at the position perpendicular to the surface of pile side; the installed sensor shall stick close to the surface of pile body and the sensitive axis of sensor shall be parallel with the center axis of pile; the sensor cannot slide during hammering;
5. When the strain sensor is being installed, its original strain value shall be monitored; the initial strain value of sensor after installation shall not be too large.
