JP-7857037-B1 - Non-destructive testing method and apparatus for detecting internal deformation of concrete.

JP7857037B1JP 7857037 B1JP7857037 B1JP 7857037B1JP-7857037-B1

Abstract

[Problem] To provide a method for measuring the propagation speed of elastic waves that penetrate the inside of concrete, a non-destructive testing method for determining the presence or absence of deformation inside concrete, and apparatus thereof, which enable non-destructive and accurate testing of deformation inside concrete. [Solution] The method for measuring the propagation speed of elastic waves calculates the propagation speed of elastic waves as they pass through the concrete 5, based on the transmission time of the elastic waves generated by the impact on the concrete 5 and the round-trip time of the elastic waves within the concrete 5. [Selection Diagram] Figure 1

Inventors

岩野聡史

Assignees

リック株式会社

Dates

Publication Date: 20260512
Application Date: 20241030

Claims (2)

A non-destructive testing method for determining whether there is deformation inside concrete, characterized by performing a calculation method at multiple measurement points on the concrete to be measured to calculate the product of the ratio of the transmission time of elastic waves generated by impact on the concrete to be measured, the travel time of the elastic waves inside the concrete, and a predetermined constant, and determining whether there is deformation inside the concrete based on whether there is an abnormal value in the product of the ratio and the predetermined constant measured at those measurement points.
A striking means for striking the concrete to be measured, A receiving means for receiving elastic waves generated by the impact by the aforementioned impact means, A measuring device comprising: a calculation means for calculating the product of the ratio of the transmission time of the elastic wave through the concrete, determined by reception by the receiving means on a surface opposite to the striking surface of the concrete, and the round-trip time of the elastic wave through the concrete, determined by reception by the receiving means on the striking surface, and a predetermined constant ; This measuring device includes a determination means for determining whether or not there is any deformation inside the concrete based on whether or not there is an abnormal value in the product of the ratio calculated at multiple measurement points on the concrete to be measured and the predetermined constant , A non-destructive testing device for detecting the presence or absence of internal deformation in concrete, characterized by comprising the following features.

Description

This invention relates to a non-destructive testing method for determining the presence or absence of deformation inside concrete , and a non-destructive testing apparatus for determining the presence or absence of deformation inside concrete. Concrete structures can deteriorate over time with prolonged use. For example, highway bridges experience significant deformation due to aging, fatigue from heavy vehicle traffic, and salt damage, among other harsh environmental factors. Furthermore, concrete structures can develop internal defects such as voids and pitting during construction. Given this situation, non-destructive testing, which directly tests structures without damaging them, is an effective means of checking the occurrence of internal concrete deformation at the time of construction and for periodic inspections in the maintenance and management of concrete structures. In particular, non-destructive testing methods that have fewer constraints for application and can be carried out efficiently in a short time are effective. While various non-destructive testing methods exist, the impact elastic wave method is known as a non-destructive testing method that receives elastic waves generated by impacting a concrete surface (see, for example, Non-Patent Document 1). Annex A of Non-Patent Document 1 describes a method for measuring elastic wave propagation velocity using propagation time differences, and Annex B describes a method for measuring elastic wave propagation velocity using the frequency characteristics of multiple reflections; both methods are standardized. Japanese Society for Nondestructive Inspection Standard: Nondestructive Testing of Concrete - Elastic Wave Method - Part 2: Impact Elastic Wave, NDIS 2426-2:2014, Japanese Society for Nondestructive Inspection A schematic diagram shows a part of the method for measuring the propagation speed of elastic waves penetrating the inside of concrete and a method for non-destructive testing for the presence or absence of deformation inside concrete, using an apparatus for measuring the propagation speed of elastic waves penetrating the inside of concrete and an apparatus for non-destructive testing for the presence or absence of deformation inside concrete, according to one embodiment of the present invention, where (a) is a cross-sectional view and (b) is a plan view.The above diagram schematically shows other parts of the method for measuring the propagation speed of elastic waves passing through the inside of concrete and the non-destructive testing method for determining whether or not there is deformation inside the concrete, with (a) being a cross-sectional view and (b) being a plan view.(a) is a graph showing an example of an acceleration waveform received by the receiving means of the propagation speed measuring device on the impact surface side of the concrete, and (b) is a graph showing an example of an acceleration waveform received by the receiving means on the opposite surface side of the concrete. Hereinafter, one embodiment of the present invention will be described with reference to the drawings. In Figures 1 and 2, 1 represents a propagation speed measuring device (hereinafter simply referred to as measuring device 1). Measuring device 1 comprises a striking means 2, a receiving means 3, and a calculation means 4. This measuring device 1 measures the propagation speed of elastic waves inside concrete 5 of existing concrete structures, and is used in a non-destructive testing device 6 (hereinafter simply referred to as testing device 6) for non-destructive testing of the concrete 5. The striking means 2 applies an impact to the concrete 5 by striking it, causing elastic waves to propagate within the concrete 5. In this embodiment, the striking means 2 consists of one striking means 2a and another striking means 2b. One striking means 2a is for measuring the transmission time (one-way transmission time) of elastic waves inside the concrete 5. For example, a hammer or a steel ball can be used as the striking means 2a. In the illustrated example, a hammer is used as the striking means 2a. The other striking means 2b is for measuring the round-trip time of the elastic wave inside the concrete 5. Examples of other striking means 2b include a hammer or a steel ball. Preferably, the other striking means 2b uses steel balls with different masses depending on the thickness of the concrete 5. That is, it is preferable to prepare multiple types of steel balls with different diameters, i.e., masses, in advance as other striking means 2b, and to select the appropriate one according to the thickness of the concrete 5 being measured. Furthermore, the first striking means 2a and the other striking means 2b do not need to be separate and distinct; they may be the same. The receiving means 3 is an accelerometer (accelerometer sensor) for measuring the transmission time and round-trip time by receiving the elastic waves applied to the concrete 5 by the