Real-Time Temperature Control for High Arch Dam Based on Decision Support System

It is important and difficult to control the temperature of mass concrete structure during high arch dam construction.A new method with decision support system is presented for temperature control and crack prevention.It is a database system with functions of data storage,information inquiry,data analysis,early warning and resource sharing.Monitoring information during construction can be digitized via this system,and the intelligent analysis and dynamic control of concrete temperature can be conducted.This method has been applied in the construction of the Dagangshan Arch Dam in China and has proven to be very convenient.Based on the decision support of this system and the dynamic adjustment of construction measures,the concrete temperature of this project is well-controlled.

Wave passage and incoherency effects on seismic response of high arch dams

The effects ofincoherency and wave-passage on the nonlinear responses of concrete arch dams are investigated in this study. A double curvature arch dam is selected as a numerical example. The reservoir is modeled as a compressible material and the foundation is modeled as a massless medium. Ground motion time-histories are artificially generated using the Monte Carlo simulation approach. Four different finite element models （FEM） are considered： uniform excitation; incoherence effect; wave passage effect; and both incoherence and wave passage effects. It was revealed that modeling multiple-supports excitation could have a significant impact on the structural response of the dam by inducing a pseudo-static effect. Also, it was concluded that the coherency effect overshadows the wave passage effect and the results obtained from non-uniform excitation of FEM, including the wave passage effect, is close to the results of the FEM when it is uniformly excited.

Calculation Model of Equivalent Strength for Induced Crack Based on Double-K Fracture Theory and Its Optimizing Setting in RCC Arch Dam

By means of fracture testing on roller-compacted concrete （RCC） three-point bending beams with two different specimen sizes, the P-CMOD complete curve for RCC was gained. Furthermore, by applying double-K fracture theory, KiniⅠC,KunⅠC, as well as the critical effective crack length and the critical crack tip opening displacement, were evaluated. Based on the double-K fracture parameters above, the calculation model of equivalent strength for induced crack was established, thus the calculation method on its initiation, stable propagation and unstable fracture was ascertained. Moreover, the finite element simulation analysis of stress field in ShaPai arch dam and the on-site observational splaying points of induced crack at different altitudes validated the reliability of the model. Finally, crack inducer′s optimal setting in RCC arch dam was studied. It improves the design level of induced crack in RCC arch dam and satisfies the necessity of engineering practice.

Study on equivalent strength for crack directors of RCC arch dam based on size effect rule

The size effect rule of roller compacted concrete (RCC) fracture toughness was reached on the analysis of fracture toughness of RCC specimens, which have been done by project team. And then the rule was applied to the calculation formula of equivalent strength of crack director in the RCC arch dam, thus a simple and useful formula was reached. The study shows that the equivalent strength of crack directors increases with the increasing intensity of concrete, but the surplus rate of strength of crack directors section decreases with the increasing intensity of concrete and the distance between centers of adjacent crack directors, and that bilateral interval crack directors are more efficient in weakening the strength of section than unidirectional interval crack directors in the case of the same distance between adjacent crack director centers. A good design for crack directors of RCC arch dam is proposed via the rule.

Arch-dam crack deformation monitoring hybrid model based on XFEM

An extended finite element method incorporated with the cohesive crack model(CCM-based XFEM) is developed in consideration of crack tip enrichment.It could improve the accuracy and is introduced into dam safety monitoring for the first time.Firstly,the proposed method is verified for a benchmark concrete beam by comparing the results with those of numerical investigations obtained by other researchers.Furthermore,it is adopted as an alternative method for building the deformation hybrid models of non-stable cracks in an arc dam,for the reason that classical FEMs are cumbersome in modeling the cohesive crack growth due to the need of remeshing the moving discontinuities.Case study proves that the fitted results of the mentioned deformation hybrid model,better than the classical statistical model,are well consistent with the measured data and reliable to forecast the development tendency of crack deformation.Therefore,the present CCM-based XFEM could provide a practical way to simulate and monitor the cracking process in concrete arch dam.

RCC Arch Dam Structure on the Taxi River and Water Storage Measure During Construction

The new structure of roller compacted concrete (RCC) arch dams is presented for extremely cold and earthquake prone areas. The influence of construction plans and improved materials on the stresses in the Taxi River dam is also given. Earlier impoundment of water is shown to not only benefit the engineering design but also improve the stresses during construction in winter. Low cement content in the concrete and artificial short joints improved the monolithic structure and the transmitted forces. The concrete plug installed in the first cooled part of the arch dam provides excellent force transmission in the arch, which increases the monolith of the earlier arch, reduces the increasing thermal stresses that occur later, and improves the deformation flexibility of the dam.