| As an important part of hydraulic engineering,the sluice undertakes the flood discharge task of the reservoir.It is safe and stable operation is very important to the overall safety and service life of the project.For water conservancy projects in high altitude and cold areas in We stern China,because these projects are located at a high altitude and often have high dams and large reservoirs,the discharge channel is affected by many factors such as strong solar radiation,large temperature difference and high-speed sediment laden flow,which is easy to cause damage and damage to the surface concrete.Therefore,the analysis and Research on the concrete deterioration mechanism and damage law of high velocity sluice in high cold area can provide corresponding theoretical support for the design,construction and operation management of high velocity sluice in high cold area.In the current research on the damage and failure of high velocity sluice in high cold area,scholars have little research on the damage and failure law of sluice under the coupling of multiple factors.In this paper,aiming at the damage and failure of high velocity discharge channel in high cold area,firstly,the damage of high velocity discharge channel in typical high cold area is studied and analyzed.Secondly,the calculation model of high velocity discharge channel in high cold area is determined through analysis.Finally,taking the left bottom outlet discharge channel of a hydropower station in high cold area as the engineering background,the three-dimensional numerical model of discharge channel is established for calculation,and the solar radiation The damage and damage law of sluice under ambient temperature and high-speed sediment laden flow reveals the causes of concrete deterioration of high velocity sluice in high cold area,and puts forward the preventive measures at different stages of high velocity sluice in high cold area.The main research results of this paper are as follows:(1)The comprehensive analysis of 9 typical engineering cases of sluice damage in high and cold regions shows that most of the sluice damage occurs 1～2 years after the completion of the project,cavitation and abrasion damage occurs when the maximum flow does not exceed 40%of the design discharge,and the impact of environmental factors such as solar radiation and environmental temperature difference on the damage of the sluice can not be ignored.In the comparative study,ASHRAE clear sky model and standard model are selected as the calculation models of solar radiation and high-speed flow in the sluice,and Finnie model,DNV model and E/CRC model are used as the calculation models of particle erosion.The simulated value of pier wall is in good agreement with the original value,so the selected calculation model can be used for the damage and failure of sluice channel in high cold area.(2)The calculation results of solar radiation on the surface of the sluice show that the solar radiation on both sides of the wall is quite different.In summer,the solar radiation is mainly concentrated on the inner bottom and bottom plate of the left wall,and the maximum radiation is 1065W/m2;In winter,it is mainly concentrated on the outside of the right wall and the top of the left wall,with the maximum value of 388W/m2.The results of temperature calculation and analysis show that the temperature on the bottom plate surface,the inner side of the left wall and the top of the side wall is higher in summer;In winter,the inner side of the sluice is basically not exposed to the sun,and the minimum surface temperature is-5.7℃.The high solar radiation area of the discharge channel basically coincides with the high temperature area.(3)The analysis of the temperature stress calculation results of the sluice shows that the tensile stress appears at the inner bottom of the right wall in January,and the instantaneous maximum tensile stress is 2.9MPa;In July,due to the direct sunlight on the inner side of the left wall and the bottom plate,the internal concrete temperature increased,and the tensile stress appeared on the surface.The instantaneous maximum tensile stress was 1.7MPa.The tensile stress distribution of the bottom plate is close to the left wall in summer and the right wall in winter.From winter to summer,the solar altitude angle increases gradually.Affected by solar radiation and ambient temperature,the tensile stress area of the right wall of the sluice gradually disappears,and the tensile stress area begins to appear in the upper part of the left wall and moves to the lower part of the left wall and the bottom plate.The cantilevered stress of the flip nose is mainly distributed in the area not exposed to the sun.The typical daily instantaneous maximum tensile stress is 2.2MPa in winter and 1.9MPa in summer.(4)The analysis of the discharge channel fluid results shows that the flow velocity increases along the way,decreases locally at the aerator,and reaches the maximum velocity of 37.2m/s at the flip bucket.The results of particle abrasion calculation show that the damage obtained by Finnie model is the largest.The erosion effect,wear range and mass loss per unit area of particles on the inner wall increase significantly with the increase of particle size(6mm>4mm>2mm)and action time;The actual wear condition is estimated based on the sediment data of the code and the hydrological stations near the hydropower station.The results show that a large number of 2mm small suspended sediment will also produce large wear under the high-speed flow.Compared with the measured results,it is found that the damage of the numerical calculation results is similar to the measured damage.In this paper,numerical simulation is used to study the damage and failure law of high velocity sluice concrete in high cold area.The research results are of great significance to explore the damage and failure law of sluice concrete caused by multi factor coupling,and have a certain reference value for preventing the damage and failure of high velocity sluice concrete in different stages in high cold area. |
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