A numerical investigation on the use of pervious concrete for seawall structures

In this study, we propose a new design of prefabricated hollow blocks, which are made of pervious concrete. The effects of thickness of block walls are studied to optimize an adequate size. The comparison of performance of porous and solid blocks is studied through fluid-solid interaction models. A polyhedral finite element formulation (PFEM) is employed to analyse responses of the structure under equivalent static and dynamic wave load conditions. The effectiveness of PFEM is verified by comparing the obtained results with those of standard finite element method (FEM) using the commercial software ANSYS. Their accuracy is also proved via the validation model of a step -beam, in which the natural frequencies are used for comparison. In static analysis, the maximum displacement of block increases rapidly when porosity of concrete changes from 5% to 35%. The optimum porosity is found to be around 20%. The variable thickness of the block walls reasonably affects the displacement resistance. However, compared to porosity, the influence of thickness is not significant. The change of Poisson's ratio slightly affects the responses of the block. For dynamic analysis, the vibration of pervious concrete block types under the impact of wave load with small duration (<20 ms) lasts longer than the case attacked by long duration shock (around 50 ms). However, the amplitudes of displacement responses by long duration impact wave are greater than that of short impact. Study also showed that the porous concrete block could significantly reduce the run-down pressure acting on the structure compared to solid block.