Study On Temperature Stress And Shrinkage Stress As Well As Seepage Characteristics Of Concrete Face Rock-Fill Dam

Modern concrete face rock-fill dams are being constructed with the trend of higher dams and larger engineering. Since the improvement of construction technology, the concrete face rock-fill dam is built gradually by adopting slipforming continuous deposit and quitting horizontal joints or the horizontal joints are treated as construction joints, therefore, the crack-resistant for concrete face slab becomes a technical problem for the safety of CFRD. Engineering practice shows that the occurrence of slab cracks especially the penetration cracks are often caused by temperature stress and shrinkage stress. Accordingly, the seepage destruction would be serious when the cracks occur and the sealing of joints in face slab is destroyed. Unfortunately, the study on temperature stress and shrinkage stress as well as seepage characteristics of CFRD hasn't been paid much attention or the study is still limited both home and abroad.In combination with the two CFRD engineerings to have been constructed, the paper deeply deals with the causes and its effects of cracks in face slab of concrete, and based on the through analysis on the characteristics of temperature deforming and shrinkage deforming in the face slab of concrete, the criteria for crack-resistant by temperature and humidity control is studied, as a result, the principle and method to determine the criteria for crack-resistant by temperature and humidity control is presented. With the analysis on validity and rationality as well as applicability of contact-friction interface element principle under general external loads offered by former researchers, the paper establishes the model of thermal conductivity and humidity conductivity of interface between slabs and cushion layer, and sets up the calculation model of temperature stress and shrinkage stress, by discussing the math model established by former researchers for concrete thermal field and temperature stress as well as humidity field and shrinkage stress, the paper provides the math model for analysis of concrete temperature shrinkage stress. The paper also studies the characteristics of concrete face slab structure and its construction, then the physics models for analysis of thermal field and humidity field of concrete face slab ,and the mechanics model for analysis of temperature stress and shrinkage stress of concrete face slab are worked out, meanwhile, the relevant solutions to someproblems in operation of the models are provided, as a result, a set of rather systematic FEM for analysis of temperature stress and shrinkage stress of concrete face slab is provided. Based on the water flow movement performance of equal-width crack and seepage mechanism of CFRD, the paper founds the model for seepage calculation of joints and cracks in face slab, and offers the equivalent quasi-continuum model for seepage calculation of face slab with intensive cracks, moreover, the seepage calculation model and calculating cases of CFRD are analyzed and some relevant solutions are accordingly introduced. Finally, in combination with one CFRD project to have been completed, the paper engages the following analysis on the temperature stress and shrinkage stress as well as temperature shrinkage stress of concrete face slab, and the seepage characteristics of dam body, obtains the varieties and distributions of temperature stress, shrinkage stress and temperature shrinkage stress, and seepage regulations of CFRD. The calculation results are in consistent with the field observed value, this proves that the models obtained in the paper are reasonable.The innovation points in the paper conclude the following: 1. According to the characteristics of temperature deforming and shrinkage deforming in the face slab of concrete, the principle and method to determine the criteria for crack-resistant by temperature and humidity control is offered. 2. The math model of thermal conductivity and humidity conductivity of interface between slabs and cushion layer is established. 3. The calculation model of temperature stress and shrinkage stress of interface between slabs and cushion layer is set up. 4. A set of rather systematic FEM for analysis of temperature stress and shrinkage stress of concrete face slab is provided. 5. The seepage calculation model of CFRD is obtained.The models and methods obtained in the paper present a lot in principle for the analysis of temperature stress and shrinkage stress as well as temperature shrinkage stress of the face slabs of CFRD, and for the analysis of seepage of CFRD. The calculation results have very important value in references and application.