LIQUEFACTION DETECTION METHOD OF GROUND AND DEVICE THEREOF

PROBLEM TO BE SOLVED: To contrive to predict liquefaction with high accuracy even when gas is dissolved in groundwater by blocking the upper end of a hollow pipe and guiding the grondwater produced by an excess void hydraulic pressure into this hollow pipe. SOLUTION: The upper end of a hollow pipe 1 is blocked while a strainer section 4 is formed on a lower side surface. This hollow pipe 1 is set up in the ground which is subjected to a liquefaction area. During earthquake time, the water level in the hollow pipe 1 rises while the air pressure in a sealed air chamber 2 in the hollow pipe 1 is increased. The increased amount of the air pressure in the sealed air chamber 2 is measured with a pressure gauge 3. Furthermore, the amount of rise in the water level in the hollow pipe 1 is measured directly with a hydraulic pressure gauge 5, which makes it possible to estimate the degree of liquefaction of the ground by determining the increased amount of an excess void hydraulic pressure in the ground even when the gas dissolved in the groundwater is dissolved out and mixed into the sealed air chamber 2 in the hollow pipe 1. It is, therefore, possible to predict the degree of liquefaction even when gas is dissolved in the ground water.