High water-pressure test in the borehole and its application in hydroelectric project

摘要

In underground projects such as pressure diversion tunnels, reservoir dams and underground powerhouse, with the pressure of 0.3MPa, 0.6MPa, 0.9MPa, the conventional water-pressure test can't reflects the percolation properties of rock mass under the actual water pressure. Because of the effects of high water head, the macro-fissures in rock mass may open or extend, changing the permeability. Rock stratums are not permeable under low pressure, but permeable under high pressure and its permeability increase obviously. So it is very necessary to take high pressure water-pressure test in these projects. Only at the position of the rock mass in the exploration holes and in accordance with the actual water pressure, can the water-pressure test achieve reliable information about rock mass's permeability. Application in many project shows that the light, convenient and practical borehole high pressure water-pressure test system we developed has stable and reliable property, high precision, and can be used continually and repeatedly, so that the boring and test period can be shortened greatly, the cost decreased. It is a set of ideal facility for rock mass permeability test for underground projects.