Ultrasonic wave head wave phase reversal testing method for depth of shallow fracture in surface of concrete

Abstract

The invention discloses an ultrasonic wave head wave phase reversal testing method for the depth of a shallow fracture in the surface of concrete. The method includes the following steps that (1), floating dust and dirt on the surface of a measured object are removed, whether water or steel bars or other foreign bodies exist in the fracture or not is observed, and it is guaranteed that the measured object is dry; (2), ultrasonic wave measuring points are symmetrically arranged in pairs with the measured fracture serving as the center, the measuring points are numbered in pairs, and each measuring distance is the distance between the inner edges of each pair of transducers; (3), ultrasonic wave measuring points are arranged on one side of the measured facture in pairs, the measuring points are numbered in pairs, and each measuring distance is the distance between the inner edges of each pair of transducers; (4), sound and time measurement without fracture crossing is conducted; (5), sound and time measurement with fracture crossing is conducted; (6), in the measurement with fracture crossing, when head wave phase reversal is found in a certain measuring distance, the depth value of the fracture is calculated through measured values of the measuring distance and two adjacent measuring distances. By means of the ultrasonic wave head wave phase reversal testing method, whether ultrasonic waves diffract to the bottom of the fracture or not is judged by observing the head wave phase change, and then the depth of the shallow fracture in the surface of the concrete is accurately detected.

Description

technical field [0001] The invention belongs to the field of non-damage detection of main structure concrete, and in particular relates to a method for testing the depth of shallow cracks on the surface of concrete by using ultrasonic first wave phase change, which is suitable for in-situ testing of building structural components. Background technique [0002] Concrete is a heterogeneous and brittle material composed of aggregates, cementitious materials, and gas and water trapped in them. Volumetric deformation occurs as concrete hardens under conditions of temperature and humidity changes. Due to the inconsistency of the deformation of various materials, the initial stress (tensile stress or shear stress) is generated due to mutual restraint, so that there are tiny cracks that can be observed by the naked eye on the bonding surface between the aggregate and the cement stone or the cement stone itself. [0003] In order to know the depth range of these cracks and know whe...

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Problems solved by technology

[0005] The purpose of the present invention is to overcome the deficiency that the testing method of the prior art often can not obtain the accurate testing result in concrete engineering practice, provide a kind of supersonic first wave phase reversal testing method of shallow crack depth on the concrete surface, the testing method The accuracy of the test results is higher

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