Arch Dam Abutment Stability Analysis Method Based on Plastic Volume Ratio and Its Rate of Change

The stability of the arch dam mainly relies on the abutment rock mass, so it is vital to study the stability of the abutment. To overcome the subjective nature of the plastic zone penetration assessment method, this paper proposes the turning point method for the change rate of the plastic volume ratio for quantitatively determining the overload safety factor and the equal plastic volume ratio method for evaluating the reinforcement effect. Using the above methods, a three-dimensional nonlinear finite element analysis is conducted on the abutment stability of the GX arch dam project. The results show that before reinforcement, the overload safety factor for the left abutment is 4.98, and for the right abutment, it is 5.62. After reinforcement, the overload safety factor for the left abutment is increased to 5.36, and for the right abutment, it is increased to 5.82. The overload safety factors for the left and right abutments increased by 7.63% and 3.56%, respectively, indicating that the reinforcement measures taken were reasonable and effective.