| Geological environment will be affected seriously by water impoundment of the Three Gorges reservoir. Some old landslides located on the bank of the reservoir may be revived and even losing stability, which is harmful to the Three Gorges engineering and people.As far as concrete face rockfill dam(CFRD) is concerned, its security is related with the rheological deformations of rockfill structure, which has been showed by correlative phenomenon of Tianshengqiao CFRD dam. This problem has attracted many workers in this field.So this paper is devoted to the rheological characters of geotechnical materials and numerical analysis of deformation and stability of landslide, including rheological tests, rehological mechanisms, and rheologic theory of sliding zone soils and rockfill as well as the analysis of deformation and stability of Xietan landslide in the Three Gorges with nonlinear finite element method(FEM).(1) Based on general review on the development of geotechnical rheology, especially integral model(IM) and differential model(DM), some questions of rheological model(RM) have been pointed out. An integral type of rheologicalIVequation(ITRE) for linear visco-elastoplastic RM is presented. Through comparing it with 4 kinds of basic DM such as Maxwell model, Bingham model, Kelvin model and Cunshan model, it is proved that such ITRE suits to not only viscoelastic RM but also visco-elastoplastical RM. According to the series type of 4 kinds of basic RM, a general ITRE is presented. When creep nucleus in the ITRE is a negative exponential function, corresponding general DM can be obtained and some mistakes in current paper have been pointed out. It has been proven that the IM and DM can be interchanged not only for the visco-elastic RM but also for the visco-elastic plastic RM. These results promote the new development of rheological theory.(2) A stress-control type of triaxial rheological compression apparatus has been refitted on a strain-control type of triaxial compression apparatus, and the creep tests of sliding zone soils and rockfill have been performed with it. The data acquisition of test apparatus is reliable.(3) For the rheologic mechanism and model of the sliding zone soils ate Xietan landslide, a Singh-Mitchell stress-strain-time model and a Mesri stress-strain-time model, as well as their parameters, are presented according to the test data. In spite of the fact that these models match the basic trend of the test data, the strain rate of the models in equal-speed creep phase is larger than that of test curves obviously, which shows that the abilities of simulation of rheological characters of sliding zone soils with Singh-Mitchell model and Mesri model are not very good. So idea of subsection simulation to creep process and a modified Mesri stress-strain-time model is present. New model can show the basic law of attenuation, equal-speed and stability phases of the creep. It is a generalized Mesri stress-strain-time behavior. A modified Mesri stress-strain-time model and its parameters of sliding zone soils in Xietan landslide have been given through subsection simulation of attenuation, equal-speed and stability phases of the creep curves. It has been shown that the simulation capability of the new model has been enhanced significantly. Furthermore, it can also simulate the accelerate creep phase.(4) Base on the triaxial creep tests a Duncan-Chang E ~μ/ model concerned with time effects is formulated to characterize the stress-strain-time behavior of slidingzone soils, whose equations of tangent elastic module and tangent Poisson's ratio with time effects are given. 12 parameters are in the newly-developed model in which k, Rf, Gand D are the functions of time. All parameters can be obtainedthrough triaxial creep tests and normal triaxial compression tests. So the time factor is involved into constitutive model of soil material, which connects the constitutive model with rheological characters of the material. For the new model, its parameter tests are not diffic...
|
PDF Full Text Request