| 摘要 |
PROBLEM TO BE SOLVED: To properly predict liquefaction corresponding to the properties of soil, even if boring is not performed. SOLUTION: In a liquefaction determining method, at first, vertical steady excitation is conducted at the excitation point 3 set on the surface 2 of the target ground 1, to generate Rayleigh waves and the vertical amplitude of the Rayleigh waves and the passing timeΔt thereof are measured at measuring points 5 and 6 at each frequency. Next, a measured passing timeΔt is used to calculate the phase velocity (c) of the Rayleigh waves at every frequency to calculate dispersion characteristics and the S-wave velocity structure of the target ground 1 is determined from a dispersion curve (104-106). Next, the S-wave velocity structure is used to specify a target layer, and the phase velocity (c) and the corresponding frequency (f) are calculated in the target layer and the up and down amplitude (w) and phase velocity (c) of the S-wave velocity structure corresponding to the frequency (f) are used to calculate the internal attenuation (h) of the target layer by a predetermined calculation formula (107-109). Next, the calculated internal attenuation (h) is used to estimate the properties of soil of the target layer, and the need for determining liquefaction is judged (110). |
