Reaearch on Skempton's coefficient B based on the observation of groundwater of Changping station

Based on isotropic linear poroelastic theory and under the undrained condition, we summarize three equations connecting the Skempton's coefficient B with the groundwater level. After analysis, we propose a method to calculate the Skempton's coefficient B according to the relationship between water level and tidal strain. With this method we can get the value of B without the earthquake occurrence, which can provide the high frequency waves for research. Besides, we can also get the in-suit Skempton's coefficient B without the experiment of rock physics. In addition, we analyze the observed data of Changping station recorded in groundwater monitoring network (abv., GMN) before and after the Wenchuan M_S8.0 with this method, and find out there's a slight change of the value of B after the seismic waves passed by, which implies that the propagation of seismic waves may have brought some variations to the poroelastic medium of the well.