Stability Analysis And Numerical Simulation Of Multi-Structure Embankment In Seasonal Frozen Area

The stability of the Yellow River embankment is an important and difficult issue in the construction of water conservancy projects in China.Over the years,the Yellow River basin has been affected by extreme weather conditions,urban development,environmental pollution and other complex factors,making the stability of the Yellow River embankment face great challenges.Every winter,the Yellow River embankment is affected by extreme temperatures and experiences several freeze-thaw cycles,during which the soil is subjected to freezing,expansion and thawing,resulting in the destruction of fine soil particles and minerals in the embankment and changes in the microstructure of the soil,which affects the shear strength of the soil.The number of freezing and thawing increases with time,which reduces the strength of the embankment,and is accompanied by the scouring and erosion of the Yellow River,which increases the occurrence of embankment collapse.Therefore,the analysis of embankment stability under the action of multi-field coupling can deepen the understanding of embankment stress mechanism,improve the safety of water conservancy construction,and provide better theoretical guidance for maintaining the stability of the Yellow River embankment.This thesis carries out triaxial consolidation undrainage tests on different soils,different moisture contents,and different number of freeze-thaw cycles,and analyzes the effects of different factors on the mechanical properties of embankment soils after freeze-thaw cycles according to the test results;and analyzes the stability of embankment under the coupling effect of freeze-thaw seepage through field investigation and the results of triaxial tests,and analyzes the stability of embankment according to different scour patterns,and the results obtained are as follows:(1)Soil moisture content and ultimate stress are inversely proportional,the higher the moisture content,the weaker the shear strength of the Yellow River embankment soil;under the same moisture content,the more times the soil experiences freeze-thaw cycles,the lower the shear strength;the difference between the ultimate stress of loamy soil and sandy soil under 50 k Pa circumferential pressure is not large,and with the increasing circumferential pressure,the ultimate stress of sandy soil under 100 k Pa and 150 k Pa is larger than that of loamy soil.(2)Under the same freeze-thaw cycle,the cohesion and internal friction angle decrease with the increase of water content;the freeze-thaw cycle decreases the cohesion of soil,but has little effect on the internal friction angle;under the same water content and the same number of freeze-thaw cycles,the internal friction angle of sandy soil is higher than that of loamy soil,but the cohesion of loamy soil is higher than that of sandy soil.(3)There is a degradation effect of water level decline on the embankment stability,the precipitation period reduces the embankment safety coefficient by 0.03,and the freeze-thaw effect reduces the embankment safety coefficient by 0.08 on average,which is much higher than the effect of seepage on the embankment stability;under the coupling effect of freeze-thaw and seepage,the embankment safety coefficient decreases by 0.11 at the maximum.(4)Different scour patterns have different effects on the stability of the embankment.The safety coefficients of the embankment are 1.29,1.26 and 1.28 under the vertical scour pattern,and 1.21,1.20 and 1.23 under the erosion effect,with the greatest decrease under the erosion effect;the safety coefficients are the lowest during the precipitation period under different working conditions,so close attention and maintenance of the embankment safety are required during the annual precipitation period.