Numerical Analysis Of Roller Compacted Concrete Gravity Dam’s Thermal And Stress Field Based On The Equivalent Age

In recent years, roller compacted concrete gravity dams had been widely used in lots of hydropower projects at home and abroad. However, the cracking arond RCC gravity dam’s body still existed during construction, whose one main reason was the thermal stress. Therefore it is necessary to carry out a delicated simulation analysis for the construction of RCC gravity dam and determine the stress field’s sensitivity of temperature.Firstly, this paper conducted a series of hydraulic concrete strength tests at different curing temperatures to verify the applicability of equivalent age method. Then, based on the test data of concrete materials used in Longtan RCC gravity dam, this paper fitted the relationship between roller compacted concrete’s elastic modulus, creep degree, splitting tensile strength with age. Afterwards, according to RCC gravity dams’ characteristics of casting and rising by layers, birth-death element modules and APDL technology were adopted in widely used finite element software ANSYS. In this way, the numerical simulation of RCC gravity dams’complex and random process during construction was achieved, which was validated by temperature measuring data in site. In addition, the thermal results of different casting temperature and shutdown in summer were also compared in the analysis. When conducting the stress analysis, this paper introduced the equivalent age theory based on Arrhenius function. Hence two different calculating programs were choosen to compare their different effects on the dam’s stress field. Finally, crack index was applied to judge the risk of cracking in the dam during construction and analysis cracking’s sensitivity to temperature.The results showed that, when considering the equivalent age, compared to the actual age, the peak tensile stress of all nodes could significantly be reduced. Regardless of which method, external nodes constructed in summers suffer obvious peak tensile stress, while external nodes constructed in winters suffer low tensile stress.When considering the actual age, the maximum stress in altitude direction mainly concentrates in basis area of the dam. If the equivalent age is considered, stress in altitude direction showed longitudinal distribution, but not the seasonal characteristics along the altitude direction. Stress of strong and weak constraint zones in altitude direction is also small.If the actual age is considered, crack index in altitude direction of strong constraint zones turns to be lager. Not taking protective measures, horizontal fracture would take place in basis parts. To the equivalent age, there is no risk of horizontal fracture in basis parts.Method of equivalent age although underestimates the risk of cracking of various parts in the dam, especially the strong basis constraint area.However, but can also be a side show that a part of RCC gravity stress distribution is very sensitive to temperature. But from the side, it also shows that the RCC gravity dam’s stress distribution is very sensitive to temperature.