1.Introduction
The geokon Model 1300 (A-9) Retrievable Extensometer is designed primarily for short-term measurements of deformation in boreholes in concrete, rock, etc. The system is used in both pre-cast and cast-in-place concrete piles in plate load tests in rock and anywhere deformations need to be measured in boreholes, either drilled or cast in to the structure being analyzed.
The system consists of pneumatically actuated anchors with spring-loaded transducers that are connected to one another in series by a single connecting rod. When installed, the anchors are fixed in place and the transducers measure the deformation between the anchor positions. The connecting rods are held in tension to eliminate errors due to bowing and friction. Connecting rods of fiberglass, graphite epoxy, and stainless steel are available.
The standard system is designed to be used in a pipe crafted of either plastic or steel, with an I.D. of 46 to 53 mm (1.811 to 2.086").
Figure 1: Model 1300 (A-9) Retrievable Extensometer Anchor