Dynamic Damage Analysis Of CFRD Slab Considering The Nonuniformity Of Concrete

The development of China’s economy has led to a sustained increasing demand of electricity. Therefore, as a clean and sustainable energy, the hydroelectric energy has been rapidly developed. More and more hydropower stations have been built in Southwest China where hydraulic energy resource is abundant. However, the complex geological conditions, high intensity seismic region, high ground stress and high osmotic pressure for instance, in Southwest China put forward higher requirements for the construction of hydraulic engineering. The concrete face rock-fill dam (CFRD) is widely used in engineering due to its simple structure, low cost, flexible construction et al.As the main impervious structure which affects the safety operation of the dam, the concrete face slab is a typical multiphase inhomogeneous composite material. Moreover, some weak links of the concrete face slab are inevitably due to the processing technology, for instance mixing, transportation, construction et al. Previous numerical simulation studies on concrete face slabs, which are simplified as homogenous and linear elastic material, may derive deviation between simulation and actual stress distributions. As the main impervious structure, the face slab is a guarantee to the normal operation of CFRD. Therefore, it is significant to illuminate the mechanism of damage of the face slab when subjected to seismic load on a meso-mechanics level.Combined meso-mechanics with the inhomogeneous property of concrete together, the present papar achieved the dynamic response of CFRD when subjected to seismic load. Hence, the damage development mechanism and failure mode of the face slab under seismic condition are achieved. The specific work is as following:(1)The meso-mechanic model of the concrete face slab was established and the mechanical parameters in the elements of the face slab were distributed according to Weibull probabilistic distribution. By the self-compiled FORTRAN program, the mechanics properties of the discrete elements were assigned. Consequently, the influences of the heterogeneity of components on the concrete elastic modulus and the tensile strength were analyzed.(2)Based on meso-mechanics theory, the random of Yang modulus and tensile strength of concrete were considered. Two-dimensional finite element analysis was employed to study the damage of face slab of CFRD under seismic load. The results showed that the nonuniformity of concrete has a significant influence on the damage of face slab. With the same homogeneity index, the damage distribution range and damage degree of face slab are basically the same. When the homogeneity index was different, the damage distribution range scattered with the decrease of the homogeneity index. On the contrary, the damage distribution range was narrowed with the decrease of the homogeneity index.(3)Meso-mechanics and elastic-brittle damage models were applied to analyze the CFRD with reinforced measure in the slab under the static state and strong earthquake condition. The results showed that steel bars in concrete slab can weaken the region of slab damage. Furthermore, the region of damage will be more obviously narrowed by double layers than single layer with the same steel ratio. When the reinforcement methods of CFRD are the same, the region of damage will be narrowed with the increase of the steel ratio. The research results could provide theoretical support for the design of reinforcement methods and steel ratios in CFRD.