UNDERGROUND DISPLACEMENT MEASUREMENT DEVICE

PROBLEM TO BE SOLVED: To provide an underground displacement measurement device that endures long-term use because of high water resistance, and enables accurate measurement, even when the device is installed in the underground having a high groundwater level. SOLUTION: This underground displacement measurement device includes a cylindrical storage member, an upper end blocking section for blocking the upper end section, a lower end blocking section for blocking the lower end section, and a measurement section forming section to be stored in the cylindrical storage member. The measurement section forming section includes a detecting section constituted by an FBG, a single optical fiber cable for transmission for transmitting the detected detection signal, a covering/protecting section for covering and protecting the detecting section and the optical fiber cable for transmission, and a tension applying member for connecting the lower end to the lower end blocking section and applying tension to the covering/protecting section. The optical fiber cable is inserted from the outside into the cylindrical storage member, is folded after installing the detecting section, and goes out to the outside. COPYRIGHT: (C)2008,JPO&INPIT