| 摘要 |
PROBLEM TO BE SOLVED: To provide an investigation apparatus for cavity volume under a structure of river bulkhead or the like, and an installation base such that a collapse and a subsidence of an earth layer in the back of a lining bulkhead concrete block can be easily and securely detected and an accident and a disaster caused thereby can be prevented.SOLUTION: A measurement box 2 is formed into a rectangular housing. A fixed frame 4 is stacked on a top-side observation window 3, which is fixed to the measurement box 2 with a fixed frame 4. On a lower side of the observation window 3, a measurement rule 5, a line weight 6, and a detection line cable 7 connected to one end of the line weight 6 and tensed around a pulley 9 are run through a guide pipe 10 joined to a bottom part of the measurement box 2, and the other end thereof is connected to a head of a sinking weight 11 buried in a ground earth layer a3.SELECTED DRAWING: Figure 3 |
