Corporate Office, NHPC, Faridabad
The hydraulic fracturing technique for in-situ stress measurement has been adopted for power house cavern in Chamera Hydroelectric Project Stage II. In this technique, the portion of the borehole in between the two packers is pressured till such time that the rock fractures or an existing fracture opens. The pressure is then reduced such that the fracture closes. The pressure is increased again and this cycle is repeated two or three times. The information regarding the pressure at which the rock fractures and one at which the existing fracture closes are used to calculate the in-situ stresses. The magnitude of the principal horizontal stress has been calculated ranging from 2.72 MPa to 11 MPa. The direction of maximum horizontal stress is tallying with the Himalayan trend in this area.
