SIZE MEASURING DEVICE FOR SOLID IN SOLID-LIQUID MIXED FLUID AND METHOD

PROBLEM TO BE SOLVED: To provide a size detection device for solid in solid-liquid mixed fluid and a method capable of detecting the size of a solid, such as a consolidated body of earth and sand included in muddy water, at a desired spot, such as the inside of a shield machine. SOLUTION: This size detection device for solid in solid-liquid mixed fluid is equipped with a radio wave transmission-reception means T, R for transmitting a radio wave into a pipe line P in which the solid-liquid mixed fluid comprising mixed solid and liquid flows and for receiving the radio wave propagated through the solid-liquid mixed fluid, and a means for measuring the average size of the solid in the solid-liquid mixed fluid based on a reception level of the radio wave received by the radio wave transmission-reception means T, R or on the state of the change with time of a propagation loss of the radio wave.