Abstract
The dynamic characteristics of concrete are the key point of the dam seismic safety design. In order to study the dynamic characteristics of concrete, a CT scan test of concrete under dynamic load was carried out; CT scan images of the concrete loading process were obtained. Based on the definition of integrity, integrity area, and intercepted sections in the quantitative zoning theory, the concrete CT images were divided into the hole or crack area ( P 0 − λ 1 ), hardened cement stone area ( P λ 1 − λ 2 ), and aggregate area ( P λ 2 − 1 ). And the determination method of partition threshold is studied. Then, based on the CT resolution unit, a concrete numerical calculation model of structural random is established, and the numerical simulation experiment of concrete under uniaxial dynamic load is carried out. The results show that the concrete numerical calculation model of structural random is very close to the actual mesostructure of concrete, and the interface thickness between aggregate and hardened cement is very close to the actual interface thickness (which is 40~50 μm). Under the action of dynamic load, the damage of the sample is mainly concentrated in the upper part of the sample, and the damage is easy to occur at the initial defect place, and the damage occurs at multiple points at the same time. The damage crack is relatively straight, the phenomenon of the crack passing through the aggregate is obvious, and the crack expands along the fastest path of energy release.
Highlights
The dynamic characteristics of concrete are the key point of the dam seismic safety design
The results show that the concrete numerical calculation model of structural random is very close to the actual mesostructure of concrete, and the interface thickness between aggregate and hardened cement is very close to the actual interface thickness
The computed tomography (CT) test of concrete under dynamic uniaxial compression was carried out, and the concrete scanning images were quantitatively divided based on the damage zoning theory, and a structural random type numerical concrete model was established; the mechanical properties of concrete under uniaxial dynamic compression stress were studied by using the model
Summary
The mechanical properties of concrete are related to the safety evaluation of the dam concrete structure under dynamic load, which is the focus of current research. Wang et al [21, 22] have established the three-dimensional numerical model of a coal sample based on a CT scanning image and studied the seepage and deformation characteristics of different pore-fracture structures of coal at different temperatures. The elements of these models have great singularity, and the thickness of the interface in the model is large, which still has a certain gap with the real concrete To this end, the CT test of concrete under dynamic uniaxial compression was carried out, and the concrete scanning images were quantitatively divided based on the damage zoning theory, and a structural random type numerical concrete model was established; the mechanical properties of concrete under uniaxial dynamic compression stress were studied by using the model.
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