Abstract
Water has a crucial effect on the time-dependent behavior of rocks. The long-term cyclical fluctuations of reservoir water level lead to dry–wet (DW) cycles of rocks on reservoir bank slopes, making this influential factor more complex. To deeply understand the time-dependent behavior of rocks under DW cycles, argillite from the reservoir bank slope of Longtan Hydropower Station was used to perform a series of triaxial creep tests. Subsequently, based on analysis of creep test results after different DW cycles, a damage nonlinear Burgers viscoelastic-plastic (DNBVP) model considering the effect of saturation–dehydration cycles was proposed by introducing a nonlinear viscoplastic body and a damage variable describing DW cycles. Then, the three-dimensional creep equations of the new model were derived and its creep parameters were identified. Comparison between the theoretical curves and the test results shows that the theoretical curves of the DNBVP model were able to describe rock creep tests results after different DW cycles. Furthermore, by comparing classical creep models with the proposed model, it was found that the DNBVP model can accurately reflect the nonlinear characteristics of rocks at the accelerated creep stage. Finally, the sensitivity of the DNBVP model was analyzed and discussed, and three-dimensional central difference expressions necessary for secondary development of the new model were also derived in detail. The proposed new model with secondary development may provide a basis for improving the geotechnical design of reservoir bank slopes and the control of reservoir bank landslides.
Highlights
The time-dependent behavior of rocks is closely related to the safety of geotechnical engineering [1,2]
Three rheological stages—decelerated stage, stable stage and accelerated stage—may appear only when the axial load approaches or reaches the critical failure value of rocks [33,35]. (iii) As shown in Figure 2a–c, when the number of DW cycle is small, e.g., n = 0, 1 or 5, obvious shear failure zones are observed after sample failure, and conjugate shear fractures occur, with approximately X-shaped sample fracture surfaces
A reasonable explanation of the above phenomenon is that the mechanical properties of the samples are degraded as the number of DW cycles increases, which results in propagation of numerous micro-fissures inside the samples
Summary
The time-dependent behavior of rocks is closely related to the safety of geotechnical engineering [1,2]. Numerical studies of engineering practices and other studies show that rock instability and failure have direct relationships with time [3,4], and variation in the mechanical properties of rocks over time can lead to natural disasters, especially landslides [5,6,7,8,9]. Water is considered a crucial factor in the time-dependent behavior of rocks [10,11,12,13]. The reservoir water level undergoes dramatic cyclic fluctuations every year, resulting in dry–wet (DW) cycles affecting rocks in the hydro-fluctuation belts of reservoir bank slopes. The effect is a cumulative process, with the damage and deterioration of rocks accelerating over time [16,17], leading to the development
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
