STRATAL GAS CONCENTRATION MEASURING METHOD AND METHOD

PROBLEM TO BE SOLVED: To provide a stratal gas concentration measuring device and a stratal gas concentration measuring method by which the concentration of a gas element contained in a stratum can be grasped in a short time as the stratum is excavated by shield excavation or boring. SOLUTION: The stratal gas concentration measuring device includes a gas/liquid separating unit which separates gas elements from a fluid material in a stratum or from muddy water containing earth and sand produced by excavating the stratum, a gas retaining unit which retains the separated gas elements, a gas concentration measuring unit which measures the gas concentration of a target gas element among the gas elements retained in the gas retaining unit in correspondence to an elapsed time from the start of measurement, a stratal gas concentration corresponding information deriving means which derives information corresponding to a gas concentration in the stratum, based on the tendency of a change in the gas concentration in the gas retaining unit that is defined by the relation between the gas concentration measured by the gas concentration measuring unit and the elapsed time. COPYRIGHT: (C)2009,JPO&INPIT