Cảm biến đo dịch chuyển (Deformation Meters VW) Geokon 4430-1X
The Model 4430-1X Deformation Meter was designed for installation in crosshole sonic logging tubes in piles, to determine the loads (using the modulus and cross-sectional area of the pile) that will be transferred as a pylon is constructed on top of the pile.
Four sensors were installed, one in each of the 2 inch nominal diameter steel pipes embedded along the longitudinal axis of the concrete pile, at 90 degrees, close to the periphery.
The sensor comprised a sensitive vibrating wire displacement transducer, connected by a stainless steel extension rod (protected by a PVC tube) between two hydraulic bladder anchors. The displacement transducer had a measurement range of 3000 microstrain (approximately ±3 mm over the sensor length), a sensitivity of approx. 0.5 microstrain, and was fitted with a 30 m length signal cable which permitted connection to a datalogger at the surface.
On site, the deformation meter was attached to a threaded rod and inserted to the required depth, and set in place by actuating the hydraulic anchors via the attached high pressure tubing and hydraulic hand pump. The lower anchor was activated first and then, using a crosspiece and nut for fine adjustment, the deformation meter was tightened until the required zero reading was obtained, at which point the upper anchor was locked in place.