Research On The Displacement Monitoring Model And Monitoring Index For Arch Dam Of Xiluodu Hydropower Station

Due to the geographical imbalance of the distribution of water resources,large-scale hydropower projects in China often encounter problems of high dams and large reservoirs.Under this circumstance,arch dams are widely used because of many advantages they display.The arch dam is a high-order statically determinate structure with good structural safety.However,it is sensitive to temperature and the stability of dam foundation,and there is still possibility of damage for arch dam.Safety monitoring is of great significance for such large-scale hydropower dams.The results of dam safety monitoring can reflect the working state of the dam directly and accurately,which is conducive to the safety management and timely decision-making for the dam.The main purpose of quantitative analysis for monitoring data is to establish a mathematical model that can express the connection between monitoring effect size and external environmental factors,thus to grasp the change law of monitoring effect size,and set the monitoring index to make timely warning for abnormal behavior of the dam.As a kind of monitoring model,the deterministic model is more closely integrated with the mechanics principles and the finite element method(FEM),thus the mathematical model is more strict and can reflect the logical relationship between the effect size and the influence factors.Among all the monitoring effect size,the displacement can more intuitively reflect the working behavior of the structure,and the measured value is more stable.Establishing the arch dam displacement monitoring model and reasonably setting the monitoring index can ensure the long-term operation safety of the dam.This paper introduces the basic principle of the dam deterministic model and gives the technical path of the one-dimensional multi-measurement displacement deterministic model.Based on pre-processing software,the finite element pre-processing is realized,and the finite element mesh with higher precision is established.The model boundary calculation range is determined by model trial calculation and the weak interlayer in the dam foundation is considered.The load effect that should be included in the deterministic model considerations is determined.The model additionally considers the of the valley width deformation of Xiluodu dam,and adds it as a boundary condition to the finite element model.The establishment of temperature component and water pressure component model was completed by FEM calculation software.Through the regression analysis of the overall model and the measured values,the parameters of the aging component model are determined,and the overall deterministic model is corrected.The confidence interval method were used to make the monitoring index.In this paper,a one-dimensional multi-measurement deterministic model of the horizontal displacement of arch dam with better prediction accuracy and a well-prepared monitoring index are obtained,which is considered to have certain engineering value.