Investigation On Impact Elastic Wave Technique In Nondestructive Inspection Of Hydraulic Concrete Structures

Currently, domestic researchers has done a lot of work in strength detection and durability assessment of concrete structures, and got many progresses, but it is still lack of effective techniques in large concrete structures. This paper mainly develops impact elastic wave technique (IEWT) to solve this problem. The development history and fundamental principles of IEWT is introduced; and then, the feasibility of this technique used in project field inspection is studied by means of laboratory experiments; at last, its effective practical application in the non-destructive inspection of hydraulic concrete structure is presented by a typical example.Through a large number of laboratory experiments, the correlation between elastic wave velocity and mechanical properties of concrete is explored, and the main study of this paper can be generalized as follows:1) A series of mix proportion tests on normal concrete and air entrained concrete are conducted. The test results show that:the wave velocity increases with the age and the compressive strength of the concrete; there is a good correlation between elastic wave velocity of cube concrete specimen and compressive strength; the impact-echo method can effectively test the dynamic elastic modulus of concrete.2) The frost resistance of concrete specimens is detected with impact-echo method and the resonance method. The experimental results and theoretical analysis show that using impact-echo method to detect the frost resistance of hydraulic concrete is feasible and it can be applied to the durability assessment of hydraulic concrete.3) Based on the damage mechanic theory, the damage model of concrete durability degradation is established, and this model provides a new way for the concrete durability evaluation.4) Impact elastic wave technique in the practical application of hydraulic concrete structure is introduced.