Study On Simulation Of Thermo Stresses At Abutment Cracks For RCC Gravity Dams In The Cold Area

RCC gravity dam belongs to massive concrete structure, its surface contacts with water and air. The changes of external temperature, hydration heat caused by concrete and its own restriction will affect the inner or surface stress. Therefore, cracks always occur in the mass concrete structure, water deposit of high and cold area, after a certain time, the cracks occurred before will suddenly expand and becomes a head cut crack. The head cut cracks of many gravity dam deep to dozens of meters, some even cuts the dam to half, and cause severe leak and damages the security of dam. So the research of head cut cracks becomes very important.In the mass concrete structure, the greatest reason caused the cracks is the temperature changes, it affects the stress condition greatly, temperature stress may exceed other external load caused stress. So research the distribution and discipline of temperature field and stress is to resolve questions caused by temperature, and resolve problems of temperature cracks and controls.In this article according to finite element computational theory of mass concrete temperature field and temperature stress field, based on large general-purpose software ANSYS, using APDL language to design the simulation calculation program of roller compacted concrete gravity dam temperature field and temperature stress field in construction stage and during operation period. During preparation period of this program, we consider the effectiveness of stratified pouring,construction interval,the change of modulus of elasticity,the adiabatic rise of temperature,the change of ambient temperature,concrete creep,the breach flow of the roller compacted concrete gravity dam and so on. The life and death unit is used to simulate the concrete casting process. The calculated results can more genuinely reflect thermal field and thermal stress of mass concrete behavior.This paper combines the actual working condition of RCC concrete dam in certain high and cold area and process simulate analysis, aiming at dams already creates head cut cracks, and propose series of measures and preventions.Reasearch shows that the reason cracks happens is because the upper side of dam creates the great along the dam axis direct stress. The concrete of corridor build in May,2008, till July,2008, cracks occurs from side corridor to upper dam. This time the concrete stress resistant is still low, and the stress of along the dam axis direct expanded, and cracks easily happens at the top of the corridor that vertical to dam axes at late stage.This text calculating achievement of thermal field and thermal stress field will provides the certain reference and uses an effect to similar project as head cut crack field.