Surrounding Rock Mass Classification Of Underground Power House At Pubugou Hydroelectric Power Station On Dadu River

In the construction of big underground power station, surrouding rock classification and stability evaluation are two main contents at the stage of the investigation and design. In the thesis, the main problem of the traditional methods for surrouding rock classification is discussed. The excellence and shortcomings of four classification methods for surrounding rock mass are pointed out. Then the methods used in the thesis are chosen.Based on the analysis of high stratal stress distributiom in the west region in China, three main factors affecting surrounding rock mass classification are analysed, such as: high stratal stress, high water pressure and the combination ways of structure planes. Then the relationship between rock blasting degree and rock mass integration classification is established.A brief introduction of Project Pubugou Hydroelectric Power Station Project on Dadu River and the geological conditions is given, including topographical condition, stratum lithology, geological conformation, hydrogeological conditions; physical and mechanical properties of rock mass; stratal stress and earthquakes. Based on the above, the structure characteristics of rock mass and the geological engineering properties within the region of power house are studied. Both HC and Q system are used to classify the surrouding rocks located on the roof of undergroud power house at the Pubugou Hydroelectric Power Station. The code Unwedge is apppied into searching unstable rock body on the roof undergroud power house and evaluating the stability of surrouding rock, and then the worst combination ways of strcture planes can be obtained. By considering rock blasting caused by high stratal stress and the worst combination ways of structure planes, the above two classification methods are corrected. Then the correlation, compatibility and applicability of two methods are studied. It is shown that, in the region with high stratal stress, the improved methods of HC and Q system have better correlation, compatibility and applicability if considering main factors of high stratal stress, rock blasting and poor structure planes combination.