Characteristics of In-situ Stress Field in Dahuofang Reservoir Conveying-Water Tunnel

In order to find out whether the in-situ strees field affects rock mass stability in the area of Dahuofang reservoir conveying-water tunnel,geomechanics is applied to study the tectonic appearance.The evolution of stress field is clarified and divided into four stages firstly.Furthermore, based on the data measured,the distribution model of in-situ stress field is set up.The results indicate that this region is in middle horizontal tectonic stress field and the orientation of major principal stress is nearly EW. The angle belween maximum principal stress and tunnel axes is 39-46° which affects rock masses stability.