Effect of Free Water on the Mechanical Properties and Blast Resistance of Concrete.

This study investigates the effect of free water on the mechanical properties and blast resistance of concrete. For this purpose, comparative experiments on saturated and normal concretes subjected to quasi-static compression, cyclic loading-unloading, quasi-static splitting, and dynamic compression are conducted. Thereafter, contact explosion tests are performed on saturated and normal concrete slabs. The results show that free water reduces the blast resistance of concrete slabs. This is primarily because free water alters the mechanical properties of concrete, including its compressive strength, tensile strength, damage evolution rate, and strain rate effect. Therefore, the material parameters of saturated concrete differed from those of normal concrete. It is unreasonable to employ the material parameters of normal concrete for simulating the cracks and damage modes in hydraulic concrete structures subjected to underwater explosions. Then, the material parameters of Holmquist-Johnson-Cook constitutive model for the saturated and normal concrete slabs are determined based on experimental data, respectively. Finally, the numerical simulation of concrete slabs subjected to contact explosions was carried out. The results show that the numerical predictions and the test data both for the saturated and normal concrete slabs subjected to contact explosions were in good agreement. [ABSTRACT FROM AUTHOR]