Study On Stability Of Underground Powerhouse Of Dachaoshan Hydropower Station

The paper introduces simply engineering conditions and mornitoring designs. According to the long-term observation data, analysizing emphatically variation of displacement of surrounding rocks , stress of reinforces ,load etc. getting preliminary evaluation about the stability of three tunnel chambers. Underground powerhouse and the room adjust the press of tail water are different in tunnel structure and geological characteristic, and the principle of displacement of variation of surrounding rocks is different from the biggest displacement lie on middle-low wall of backward position of underground powerhouse, considering on digging of tail water tunnel, the other is in middle wall. A curve variety is some steady, have no obvious step form, the measure points that this curve to opposite to is the parts that wall rock transform smallerly, another curve contain the mutation phenomenon, because being subjected to the influence by digging the border upon terrane cause to transmutation of wall rock enlarged suddenly, then tended to steady. Owing to skewback what subjected to force complicated, which cause to the wall rock to transform mainly, so the displacement of skewback is more biggetr than anywhere else, coMParely transmutation ia smaller at the top of skewback.. The main factor which cause to displacement of wall rock is the effect of time and space, which cause the wall rock come into being slowness distortion toward the center line of the hole room, and the coMParison is smaller that the displacement of wall rock cause to slowness distortion relative to entirely displacement, the wall rock stability standard that the Transform velocity less than 0.15%mm/d to the security of the hole room is not any threat. The stress of anchor pole is biggish at large where the arch of an arch of main factory premises, the anchor pole developped the function, and also the medium lower part of the side wall of the main factory premises and the room adjust the press of tail water. Definite rose to arrive the solid function of anchor pole. At the arch of the three biggish holeroom, the stress of the anchor pole is opposite smaller, the function that the anchor pole develop is very small. A part of the anchor pole where the medium upper part of the main factory premises and the room adjust the press of tail water have not fullly exertive their function, even some appear to the press stress. Analyzed its reason: first, the medium upper wall rock with the big scope transform for lord, but shorter anchor pole exertive obligation function only to transform of the partial district wall rock; another, arranged the anchor cables to solid the wall rock around the two great hole room which the length is 20m, and exerted about the 800 MPa stress on the anchor cable to made a big scope wall rock occur compression transform, and cause the anchor pole's stress descended, even being subjected to press. The anchor load of the obserbation anchor cable at the main factory premises and the room adjust the press of tail water have some rising of different degree, the anchor cable's anchor function have had fully exertived. Based on the result get on the analysis and coMPared to the design forecasting data and analyzed on 3-D finite element method, get the conclusion of the stability of the three hole room currently.