(1. Geotechnical Research Institute，Hohai University，Nanjing，Jiangsu 210098，China；2. Key Laboratory of Ministry of Education for Geomechanics and Embankment Engineering，Hohai University，Nanjing，Jiangsu 210098，China)
Abstract：The sandstone with weak plane is sampled from the compressive zone of the left bank dam foundation of Xiangjiaba hydropower station. Shear rheology tests are carried out for the rock by using CSS–3940YJ rock shear rheology testing machine. The test results show that the sandstone is the typical soft rock，and the rock shows significant metastable rheological property under the constant shear stress. When the stress reaches a certain level，the accelerative creep damage of rock occurs after the primary creep and metastable creep. The nonlinear rheological component is improved according to the shear creep behavior of the sandstone with weak plane，and it is equivalent to Newton dashpot when the stress is less than threshold as well as nonlinear viscoplastic component when the stress exceeds threshold. By connecting the improved rheological component and generalized Kelvin model in series，a new four-component nonlinear viscoelasto-plastic rheological model of rock is proposed，which can fully reflect the metastable and accelerative creep properties of rock material. The model has advantages of simple structure and few parameters. The constitutive equation of this rheological model is deduced；and the nonlinear creep property of rock is carried out based on the theoretical analysis. The shear rheological parameter identification of the rock is carried out based on the proposed model，and the method of parameter identification is mainly investigated when the stress level exceeds the threshold. The comparisons between calculated results of nonlinear rheological model and tested results show that the proposed nonlinear viscoelasto-plastic rheological model is available and reasonable.
孙 钧. 岩土材料流变及其工程应用[M]. 北京：中国建筑工业出版社，1999.(SUN Jun. The rheology of the geotechnical material and its engineering application[M]. Beijing：China Architecture and Building Press，1999.(in Chinese))
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2011, Vol. 30 
