| 摘要 |
A hollow sensor rod (5), which is alternately formed of narrow diameter parts (7), and large diameter parts (8) which form a tiny gap with respect to the inner face of a cylindrical iron pipe (1), is inserted into the cylindrical iron pipe (1), and both ends thereof are anchored in the cylindrical iron pipe (1). Strain gauges (13) are adhered to the outer circumference faces of the narrow diameter parts (7) of the sensor rod, the lead lines whereof being inserted in the sensor rod (5) from lead line insertion holes (7a) which are opened in the narrow diameter parts (7) said lead lines being extruded from the top part of the cylindrical iron pipe (1). If the cylindrical iron pipe (1) bends and deforms due to earth movement, the sensor rod (5) bends and deforms in line with the bending and deformation of the cylindrical iron pipe (1) by the effect of the large diameter parts (8) which form the tiny gap with respect to the inner face of the cylindrical iron pipe (1). In such a circumstance, strain arises in the outer circumference faces of the narrow diameter parts (7) which is greater than the outer circumference faces of the large diameter faces (8), and it is possible to sense bending and deformation of the cylindrical iron pipes (1) with high sensitivity by the strain gauges (13) which are adhered to the outer circumferences of the narrow diameter parts (7). |
