Physical and Mechanical Properties of Gravelly Soils Used in High Fill Project of Baihetan Hydropower Station

Abstract:

Baihetan Hydropower Station is the largest hydropower station under construction and has the world’s largest single-unit capacity. In order to avoid the flooding of the resettlement area of Qiaojia County when the reservoir is impounded， a high filling project is required. The filling material is the locally obtained gravelly soil. In this study， the particle size analysis test， the compaction test， the compression test， and the triaxial test as well as the onsite rolling test are conducted on the gravelly soils. The results show that the compaction characteristics of the soils depend on the gravel content. When the gravel （i.e.， particle size larger than 5 mm） content is 40%~70%， the soils will form a dense skeleton structure and show better compactability and mechanical properties. During the onsite rolling compaction process， it is necessary to control the moisture content based on the gravel content of the soils and the rolling equipment adopted. Gravelly soils with compaction degrees of 0.95 and 0.97 show significant differences in their compression properties and shear strength. Meanwhile， according to the stress-strain relationships of the soils， the parameters of the Duncan-Chang hyperbolic model are determined. The test results provide an important reference for the gradation and compaction design of the filler as well as the parameters of the filler for the Baihetan high fill project.