The Evolution Mechanism Of Curtain Body Performance In High-pressure Waterway And Its Influence On Seepage Safety

In order to improve the peak and frequency regulation and stable operation capabilities of China’s power grid,a large number of high-head pumped storage power stations have been built or put into production or are under construction.The design head of these pumped storage power stations is generally up to 300～1000m,and the anti-seepage curtain will withstand up to 2 With an infiltration pressure of～3MPa,the leakage problem is extremely prominent,and it is of great significance to study the mechanism of the evolution of the performance of the curtain body of the high-pressure waterway.However,due to the high seepage pressure and high hydraulic gradient of the underground water conveyance system,the environment of the lining and anti-seepage curtains is extremely complex,and there is a lack of systematic research on performance attenuation.At the same time,the relevant parameters in the numerical simulation process are difficult to determine,which is safe for the curtain body seepage control Evaluation brings many difficulties.In this paper,the multi-field coupling and seepage control safety of the curtain body of the high-pressure waterway is taken as the research object,combined with the multi-field coupling numerical model and parameter inversion model,the relevant research on the performance attenuation mechanism of the curtain body and the seepage safety is carried out.The main tasks are as follows:（1）In order to reveal the evolution law of the anti-seepage performance of the anti-seepage curtain of the high-pressure waterway,the performance evolution model of the curtain body was established from two aspects of chemical field and seepage field.First,the material properties of the grouting material and the curtain body are introduced.From the perspective of the chemical field and the seepage field,the governing equations and coupling process of the performance evolution of the curtain body on the multi-field coupling are analyzed.The mathematical model of the evolution of the performance of the high-pressure water channel anti-seepage curtain is established.On this basis,a finite element analysis model was established,the migration and diffusion process of Ca²⁺in the curtain body chemical field was studied,the law of permeability failure of the curtain body of the high-pressure water channel was revealed,and the analysis experiment of the composition of the precipitate in the drainage corridor was carried out to verify the Ca²⁺migration path.The results show that Ca²⁺precipitation is the main reason for the attenuation of the curtain body’s anti-seepage performance.The amount of precipitation can determine the current anti-seepage performance of the curtain body to a certain extent.（2）Aiming at the back analysis of the permeability coefficient of the curtain body,an inverse analysis method for the permeability coefficient of the curtain body of the high-pressure branch pipe based on ABC-SVM（Support vector machine model based on artificial bee colony optimization）is established.First,the support vector machine theory and the artificial bee colony algorithm are reviewed,and the artificial bee colony calculation is used to optimize the support vector machine parameter information;the orthogonal coefficient test design method and the finite element analysis method are combined to propose an inverse analysis model of permeability coefficient based on ABC-SVM.The non-linear relationship between permeability coefficient and seepage flow and uplift pressure is established,and then the permeability coefficient of anti-seepage curtain and rock mass is inversed according to the field measurement data.The method is applied to engineering examples to verify the effectiveness and accuracy of the proposed method.The results show that the artificial bee colony algorithm can effectively improve the global optimization effect and the generalization ability.The inversion model of the permeability coefficient of the high-pressure branch pipe curtain based on the ABC-SVM can accurately describe the nonlinear relationship between the permeability coefficient and the uplift pressure and the seepage flow.The relationship provides technical support for the analysis of the performance evolution mechanism of the high-pressure water pipe curtain body and the seepage safety evaluation.（3）Aiming at the problem of seepage safety of high-pressure branch pipe curtain body,a three-dimensional seepage finite element calculation model of high-pressure branch pipe curtain body was established,and the safety performance evaluation of curtain body seepage flow was carried out.Firstly,taking the anti-seepage performance analysis of the high-pressure bifurcated pipe curtain body of a power station as a background,comprehensively considering the geological conditions,groundwater level and the head pressure of the high-pressure bifurcated pipe area under the normal operation of the power station,the three-dimensional seepage finite element calculation of the high-pressure branch pipe curtain body The model defines the boundary conditions for seepage safety calculation.On this basis,the seepage safety evaluation of the high-pressure bifurcated pipe is carried out,the distribution law of the seepage field of the high-pressure bifurcated pipe is revealed,and the safety performance evaluation of the curtain body seepage is carried out in conjunction with the field monitoring data.The evolution law and influencing factors of the body’s anti-seepage performance.The results show that the curtain body bears about 75%～87.6%of the head pressure and has a good anti-seepage effect,but under the action of high permeability slope,the safety performance of the curtain body will be reduced accordingly,and the safety protection treatment of the curtain body is proposed,the measures provided technical support for the analysis of the performance evolution mechanism of the high-pressure water pipe curtain body and the seepage safety evaluation.