Method for evaluating long-term safety of arch dam under action of valley width shrinkage deformation

Abstract

The invention belongs to the field of arch dam safety monitoring, and provides a method for evaluating the long-term safety degree of an arch dam under the action of valley width shrinkage deformation, which comprises the following steps: firstly, predicting the limit value of the valley width shrinkage deformation of the arch dam; establishing an overall finite element model of the arch dam foundation, and performing valley width shrinkage deformation inversion based on the predicted valley width shrinkage deformation limit value; applying displacement obtained through inversion to the boundary of the finite element model, and obtaining the maximum water level overload multiple during overall deformation of the arch dam foundation and the intensity reduction multiple during instability failure of the arch dam foundation through simulation by means of a water level overload method and then an intensity reduction method; and determining the long-term safety degree of the arch dam underthe action of valley contraction deformation based on the maximum water level overload multiple and the strength reduction multiple. Extreme loads such as flood and landslide surges possibly encountered in the long-term operation process of the arch dam and gradual degradation of the material characteristics of the dam body and foundation rock mass of the arch dam along with time are considered, consideration factors are comprehensive and objective, and the method has the advantage of high accuracy of arch dam safety evaluation.

Description

technical field [0001] The invention relates to the field of safety monitoring of arch dams, in particular to a method for evaluating the long-term safety of arch dams under the action of valley amplitude shrinkage deformation. Background technique [0002] At present, a batch of 300m-level extra-high arch dams such as Jinping I, Xiaowan, and Xiluodu in my country have been impounding and operating for many years. Shrinkage (i.e. reduction in valley width). Among them, after the Xiluodu arch dam was impounded, the maximum valley width contracted by about 36mm in the upstream and 18mm in the downstream; as of June 2018, the valley width in the upstream of the Xiluodu arch dam had shrunk by 67.27mm to 87mm cumulatively, and the valley width in the downstream had shrunk by 67.27mm to 87mm. The shrinkage ranges from 75.4mm to 78.88mm, and the valley width shrinkage deformation is relatively large and the deformation trend has not stopped, which exceeds the general engineering ex...

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Problems solved by technology

[0006] However, during the long-term operation of the arch dam, the foundation rock mass and the concrete material of the dam body will gradually deteriorate, and at the same time, it may encounter extreme conditions such as floods and landslide surges. None of these methods can reflect the above uncertain factors, and it is difficult to accurately analyze the bearing capacity and safety margin of the arch dam when it encounters extreme loads under the long-term extrusion of the mountain.

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