Physical Model Test And Numerical Simulation Of Deformation Process Of Complex Landslide In Reservoir Environment

A large number of domestic and foreign examples have confirmed that in the reservoir environment,the revival of old landslides is one of the most important disaster problems that threaten the safe operation of the reservoir and the safety of the residents' lives and property.Since the Three Gorges Reservoir impounded in June 2003,hundreds of large landslides have occurred,most of which are old landslides resurrected.The research on the landslide resurrection mechanism and deformation process taking the old landslides in the Three Gorges reservoir area as the object has always been a hot issue in domestic reservoir landslide research.However,previous studies have focused on simple landslides with single-layer slip belts,and there are no studies on complex landslides with multi-layer slip belts.In order to systematically explore the deformation characteristics and resurrection mechanism of complex structural landslides under the fluctuation of reservoir water level,the paper takes the Chaiwan landslide in the Three Gorges Reservoir area with three layers of sliding zones and different permeability of sliding bodies as the prototype.Physical model tests and Combined with numerical simulation research methods,the deformation process and activity mechanism of complex structural landslides under the conditions of reservoir water fluctuations are carried out.In this study,based on the similarity theory,three landslide models with different sequence of permeability(K1 <K2 <K3)of different sliding bodies were constructed.The full-section flexible FBG grating sensor and image tracking surface marker method were used to monitor the simulated reservoir water level.The deformation process of the landslide model during the fluctuation process;based on the inversion of the landslide model test results,the numerical simulation study of the landslide deformation process under more conditions was carried out;the control law of the sliding body permeability to the complex structural landslide activity characteristics was discussed.(1)When the reservoir water level fluctuates,the deformation of the landslide is controlled by the rate of rise and fall of the reservoir water.The landslide models with different structures all show different levels of stratified activity trends.The characteristics of landslide activity vary significantly with the location of the landslide.During the rising stage of the reservoir water level,the landslide with weak upper permeability and lower permeability is more deformed,but the acceleration of the reservoir water speed will inhibit its sliding;during the stage of the decline of the reservoir water level,each structural landslide model has different degrees of displacement performance,especially precipitation At this stage,the faster the deceleration,the greater the displacement of the K1 layer sliding body with the weakest permeability.(2)Combining the results of model tests and numerical simulations,it is found that the structural characteristics of complex landslides are closely related to the permeability of layered landslides.Under the condition of the same reservoir water level rise rate,the displacement of the middle and lower sliding bodies from the front edge to the trailing edge of the landslide has a small difference,and when the permeability of the upper sliding body is stronger than that of the underlying sliding body,the displacement decreases from the front edge to the rear When the permeability of the upper sliding body is weaker than the permeability of the underlying sliding body,the displacement increases from the front edge to the rear;when the reservoir water at the same rate drops,the displacement trend of each layer of the landslide can be roughly divided into three categories:(1)When the upper sliding body When the permeability is weakest,the displacement of the upper-layer sliding body decreases backward from the front edge,and the difference between the displacement of the middle and lower layers is small;(2)When the permeability of the lower-layer sliding body is weakest,the displacement of the sliding body of each layer of the landslide increases from the front edge to the rear;(3)When the permeability of the middle sliding body is weakest,the displacement of the upper sliding body of the landslide increases from the front edge to the rear,and the displacement of the middle and lower sliding bodies decreases from the front edge to the rear.(3)At the same position of the upper,middle and lower layers of the same section,when the reservoir water level rises,the displacement trend of each layer of the landslide can be roughly divided into three categories:(1)When the permeability of the upper layer sliding body is weakest,the cumulative displacement of the upper layer sliding body is the largest,The difference between the displacement of the middle and lower layers of the sliding body is small,and the permeability coefficient of the sliding body is negatively correlated with the displacement increase;(2)When the permeability of the lower sliding body is the weakest,the displacement gap of the three-layer sliding body of the landslide is small,The displacement increment is positively correlated;(3)When the permeability of the middle sliding body is weakest,the displacement of the middle sliding body is the largest and the displacement of the lower sliding body is very small;when the water level of the reservoir at the same rate drops,the displacement of the weakest sliding body The largest,the permeability coefficient of each layer of sliding body is roughly negatively correlated with the displacement increment.