Research On Bedding Surface Features And Cracking Damage Mechanisms Of Roller-compacted Concrete Gracity Dam

The ultra-dry hardness concrete without slump was adopted in Roller-CompactedConcrete (RCC) gravity dam, meanwhile the construction method with continuouslamella casting in large area and the vibration crushing in bedding surface were used inthe RCC construction process. The RCC had been widely used in hydraulic engineeringand it possessed the advantages of rapid construction in large surface, reduction ofcement dosage, and simplification of temperature control measures etc. In the vibrationrolling procedure, the interstice and moisture in roller-compacted concrete were difficultto completely eliminate, and the phenomenon of segregation caused by transportationliquidation were hard to avoid entirely, thus it had led to the generation of weak surfacebetween layers within RCC. Currently, the experimental and numerical simulationresearches about the fracture damages between layer surfaces in RCC had beenpreceded at home and abroad, furthermore it had achieved superior results, but theresearch for RCC layer thickness and properties were not comprehensive and systematicdiscussed. According to information, especially in the analysis of the influence on thedam stress distribution and the cracks along the surface extending between the layerscaused by the construction RCC layer thickness, weren’t too much in-depth studyexisted among. In addition, for the numerical simulation of RCC gravity dam, aparticular research project was mostly valued and the research area was relativelynarrow. So, the systematic research of bedding surface features and crack damages toRCC were necessary to be conducted, and the results could be seen as a reliable basisfor the design and construction of RCC gravity dam.In this paper the research was depended on Long tan RCC gravity dam, themultiple finite element models were established based on large-scale finite elementanalysis software ABAQUS and then several works were to be made around the aspectsof RCC bedding surface features and thickness:1. The diverse roller compacted layer thickness isolator model of RCC wereestablished though ABAQUS software, and the different thickness of roller compactedlayer and the stress distribution discipline of normal concrete were analyzedrespectively.2. The diverse roller compacted layer thickness gravity model of RCC wereestablished though ABAQUS software, and the different thickness to the roller compacted layer of RCC dam and the stress distribution discipline of normal concretedam were analyzed respectively.3. The numerical simulation of cracking was conducted by the extended finiteelement method (XFEM), and then the different thickness to the roller compacted layerof RCC dam and the crack propagation discipline of normal concrete dam in diversifiedoverload condition were analyzed comparatively.The conclusions could be drawn through analyzing: above all the stressconcentration in RCC bedding surface was found obviously; meanwhile, the stressconcentration in thicker roller compacted layer of RCC dam and the crack propagationcondition were superior to the relatively thinner; and with the increase thickness of RCClayer the stress, displacement distribution to the dam in all regions and the crackpropagation discipline were more closely to the normal concrete dam. Furthermore inthe allowable circumstances of execution conditions and rolling compaction technologyin practical engineering, the security of dam and the reduction of erection time werebenefited from adopting relatively thicker layering laminate. Finally, for the high RCCdam the structure reinforcement measures should be taken to the bedding surface of theadjacent dam hell.