Determining 3D in-situ stress with a new borehole deformeter by single overcore;

In the case of Goupitan Hydropower Plant s dam foundation excavation,borehole deformation modulus and single-hole acoustic wave velocity have been measureed,and their correlation relationship is established.

Using borehole strain data to forecast the Yanjin M5.1 Earthquake,Yunnan Province,on 22 July 2006;

We also discovered at various borehole strain-meter stations tidal response(tidal factor) are separate and have orderly anisotropy.

Since the setup of the high precision borehole strain at Wushi station in 1984,9 groups of earthquakes of magnitude 6 and above,16 times in all,have occurred within the range of 300 kilometers around Wushi station.

For this reason,in this paper the bore hole strain seismograph is calibrated with the result from harmonically fitting or with the displacement measured by pendulum,then the stress corresponding coefficient of the bore hole strain can be derived and the resolution of wave eguation can be substituted approximately by the resolutio.

The scale value, which is converted from the bore hole strain, by nse of the observed values in tidal frequency band of the bore hole strain and the elastic coefficients of the bore hole corescan can be used for coverting non tidal variation of the bore hole strain into variation of the non tidal stress of the same stratum.