Simulation And Analyses Of Controlling The Thermal Stress Of Overwintering Layer Of The RCC Dam In High-Cold Area

Thermal stress and temperature control have important meanings in the construction of mass concrete structure.Similaring to normal concrete dam, RCC dam has the question of cracking in dam. Although the hydration heat in RCC dam is lower than that in normal concrete dam, thermal stress becomes the question which can't be ignored owing to its material and construction characteristics. Especially in severe cold area, abominable climatic conditions and adopting long intermission type construction mode ,it is easily to induce thermal Stress between two compact layers and internal and external of concrete, thus it could cause greater stress of tension stress concentration on the surface of upstream and downstream, and cause greater horizontal tension stress in the intermediate position of overwintering layer, which bring greater difficulty for the crack control of massive concrete. This paper takes a research on setting an artificial stress -released joint on overwintering layer and combine with thermal insulation measure on the layer, in this way to control the thermal stress of overwintering layer.The paper is based on the heat conduction theory and the three-dimensional finite element(3-D FEM) theory,the3-D FEM theory formulas of temperature field are deduced; based on the heat stress theory and the 3-D FEM theory and creep theory of concrete,the3-D FEM theory formulas of thermal creep stress field are deduced. Study method is using the 3-D finite element relocating mesh method to realize the simulation analysis for the multifactorial thermal stress control measure in the overwinter layer. Through a typical example of simulation and analyses of temperature field and thermal-creep-stress field in RCC dam with three schemes during construction stage and operating period for example the scheme without any thermal control measure and the scheme without thermal insulation but having thermal stress -released joint and the scheme with thermal stress -released joint combined thermal insulation measure . This paper systematically studies the positive effect of taking the multifactorial thermal stress control measure on overwintering layer to the crack control of dam. The results indicate that adopting the measure with stress -released joint combined thermal insulation can evidently improve crack problem of dam caused by long intermission of overwintering layer. This research provides a new way to solve crack problem of high RCCD caused by long intermission of overwintering layer in the severe cold area.