Study on Cemented-rockfill Dam in Hydropower Station Construction

Abstract

The selection of dam type is an important technical problem in hydropower station construction. Concrete face rockfill dam (CFRD) has been used to build many hydropower stations in recent years as it has less cost and can be built with local materials. In order to solve the great deformation of rockfill which may lead to concrete face and watertight seal structure of peripheral joints destroyed in CFRD, a new material named cemented-rockfill which has greater deformation modulus and higher compressive strength has been discussed. Cemented-rockfill is a kind of material made by adding little cement and water to the rockfill or sand-gravel without mixing or just simple mixing, continuously constructed by thin-layer roller compacted method. The cemented-rockfill material has an advantage over rockfill in greater deformation modulus which can improve the material property, and eliminate the probability of great deformation in rockfill dam. At the same time, the new material retains the construction method as the CFRD, so it has its great advantage. Based on the results of tests, the engineering properties of the cemented-rockfill material are analyzed including the constitutive law, strength properties, seepage properties, thermodynamics properties etc. The analysis results show that the cemented-rockfill material has many good properties for the dam construction; it has advantages both in technology and economy. Then, take the material property into consideration, the construction method and construction technologies of cemented-rockfill have been discussed. At last, the new types of dam based on this technology, named face cemented-rockfill dam (FCRD) and cemented-rockfill mixing dam (CRMD), are investigated. In FCRD, an impervious membrane for water tightness was placed on the upstream slope, concrete faced is more widely used for rockfill dams than before, at present, the two-graded compacted RCC tending to dominant in FCRD; and the spillway can be placed on the dam because of the greater deformation modulus and higher shear strength of cemented-rockfill. In CRMD, the cemented-rockfill is arranged on the main rockfill zone, and the rockfill is arranged on the secondary rockfill zone. It is less project quantity and more safety compared to CFRD.