Analysis Of Stress Field In Engineering Rock Masses

The mechanical index or parameters of rock is similar to those of other materials, they are understood and accepted easily. However geostress is one inner stress stored up in rock mass, it isn' t rock-mass' inhesion characteristics like mechanical index, but it is a mechanical state in rock masses. The stress state is generally different in similar engineering rock mass but in different space. So the stress field can be determined only by measurement. At other hand, the importance of geostress to rock engineering stands out increasingly. The technology of measuring geostress is developed increasingly too. Through personnel practice experience and relevant international literature study, the geostress development history, research status and develop trend are summarized, the domestic research achievement is also quoted in this report.It is stated systematically in the thesis the method's theories and measuring principle of all kinds of geostress determination technology. In particular the four methods recommended in 1987 by the committee of test method of the International Society of Rock Mechanics, i.e. two over-coring methods of strain relief in boreholes, hydraulic fracturing method and stress furbish measurement which measures the surface stress. Two methods' principle of three dimensional stress determination developed from the above four basic ones by Yangtze River Scientific Research Institute are presented, one based on hydraulic fracturing and hydraulic tests on preexistent fractures in single borehole, another one based on CKX-97 hollow package 3 direction strain gauge.Through measurement and data regression analysis at Shuibuya Hydraulic Project, the characteristics of stress field in complex rock mass are also revealed. The stress distribution is far from uniform in this stratified rock, the horizontal stress magnitude in hard rock layers is significantly higher the that in soft layers.