Mechanism of Splitting Failure for High Sidewall Cavern of Hydropower Station Based on Complex Function and Strain Gradient

Fan Li,Wen Xiang,Qiangyong Zhang

doi:10.3390/en14185870

Abstract

With the rapid development of society, the number of hydropower projects has increased. During the construction of these projects, due to excavation-induced unloading, the high sidewalls of the hydropower station are often subject to splitting failure, which produces many adverse effects on the construction of the cavern. In order to reveal the formation mechanism of splitting failure of hydropower stations, based on the strain gradient theory and elasto-plastic damage theory, we proposed an elasto-plastic damage softening model. Using the ODE45 program in MATLAB, we solved the numerical solution of displacement and stress of circular cavern based on our proposed elastoplastic damage model. Then, we apply the complex function method and use the Schwarz–Christoffel integral formula to obtain the mapping function from the outer domain of the high sidewall cavern to the outer domain of the unit circle. Finally, the elastic-plastic region and displacement distribution of the high sidewall cavern are obtained by mapping the obtained elastic-plastic solution of the circular cavern under the axisymmetric condition. In future research, it is necessary to further study the corresponding relationship between the internal length parameter of the material and its internal microstructure in order to accurately determine the internal length parameter.

Highlights

We propose an elasto-plastic damage softening model based on strain gradient theory and elasto-plastic damage theory
Considering the mechanical calculation model, when the length of the deep-buried horizontal cavern is large, it can be treated as a plane strain problem
R0 is the radius of the circular cavern, R p is the radius of the plastic zone

Summary

Introduction

With an increase in hydropower projects, it was discovered that some nonlinear deformations and failures occurred in the surrounding rock of caverns during the construction of these projects. The deformation failure mode of the splitting failure of the hydropower projects with a high sidewall is quite different from that of the shallow cavern, showing obvious discontinuity and nonlinear behavior. There is no clear understanding of the formation mechanism of splitting failure of high sidewall cavern, and the traditional continuum mechanics theory cannot provide a satisfactory explanation

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