Undrained examination of tidal responseof water-span lang=EN-US sty

Based on the Hsieh model, a novel but simple method is proposed to examine whether the undrained condition is satisfied for the response of well water-level to tidal stress action, by monitoring the change of amplitude and initial phase of tidal constituents of the water-level.Water-levels of the well C(Chuan)-18 and C-06 are analyzed with the examination method. The chosen amplitude and initial phase of tidal constituents (M2 and O1) of the water-level in C(Chuan)-18 and C-06 well, and theoretical tidal stress before and after the earthquakes, are calculated with the Baytap-G tidal analysis method. The result shows that the tidal response of the water-level in C-06 well was drained at first, then it was in an undrainedstate because seismic waves enhanced the aquifer hydraulic conductivity (permeability). Due to high hydraulic conductivity, the tidal response of the water-level in C-18 well meets undrained state. Finally, we figure out the Skempton coefficient and the Transmissivity of the aquifer tapped by the C-06 well, as well as the Skempton coefficient of the aquifer tapped by the C-18 well.