Application of high water-pressure test to deep borehole

Generally, conventional water-pressure test is always carried out with five phases and three pressure stages, 0.3, 6 MPa and 1 MPa. But for some Engineerings with high water pressure such as the dam and deep covered underground ones, the results of the conventional water-pressure test can’t reflect the true permeability characteristic of the rock mass. The experiment is carried out in a 500m borehole of a granite region, and the pressure stages are designed as 2, 4 MPa and 6 MPa. 21 typical segments are selected to carry out high water-pressure test and the length of each segment is 6.5 m.The seepage law of this area is obtained through high water-pressure test. The permeability is relatively low. The grouting pressure should be larger than 5MPa when treat with fracture rockmass.