Research On The Damage And Fracture Rules Of Concrete In Water Due To Explosion Loading

Concrete as a typical non-uniform brittle material, it has a broad application. Especially in recent years, with the rise of civil defense, water and coastal engineering, research on underwater concrete damage and fracture due to blast loading is of both theoretical and practical importance. Previous studies are mainly focused on air concrete damage and fracture under the blast loading, but researches on the mechanism of damage and failure of concrete medium subjected to underwater explosion shock wave are rare. This paper is based on our group research work and previous experiments, with emphasis on underwater concrete damage and fracture caused by explosive loading. Certain meaningful results are made.A simplified two-dimensional axisymmetric single-grid model is built, and the damage and failure of concrete target in different environments under an infinite plane explosion loading via numerical simulation is carried out. The damage and failure of concrete plane with different protective layers under explosion is analyzed. The protective effects of soft, hard, porous materials, as well as different combinations of the three forms are compared. A certain kind of protective form is proposed. Researches on damage and failure under blast loading of hollow concrete columns filling with different kinds of materials are analyzed.Based on the unit consumption experiment in 3rd RCC cofferdam removal of the Three Gorges Reservoir, numerical simulations via non-linear finite element explicit code LS-DYNA on blast damage of concrete in air and water were carried out. The side length of the cubic concrete is 1 meter and the charging structure is radial water-decoupling. Water-depth of 0 meters to 100 meters with charge of 50 grams as well as the case of water-depth of 25 meters with varying charge from 50 grams to 200 grams are calculated respectively. Numerical simulations fit experiment data well. The results indicate certain rules of water-depth effect on blast damage and show that the damage effect in air is much bigger. There is no significant change of explosion effect with the increasing water depth nearby blast center. However, it decreases dramatically in the outlying regions. This thesis conclude some results with certain engineering value, which can be used into the protective design of underwater concrete columns, concrete walls in civil defense projects and the cofferdam removal of water and coastal engineering.