CN-121994173-A - Ultrasonic nondestructive testing method for measuring thickness of each layer of asphalt pavement surface layer

CN121994173ACN 121994173 ACN121994173 ACN 121994173ACN-121994173-A

Abstract

The invention relates to an ultrasonic nondestructive testing method for measuring thickness of various layers of an asphalt pavement surface layer, belongs to the technical field of thickness measurement of asphalt pavement, and solves the problem that when the thickness of the traditional asphalt pavement surface layer is measured, the traditional asphalt pavement surface layer cannot accurately locate the receiving position of a reflected wave signal, cannot accurately obtain the arrival time of an echo, and the measurement accuracy is not accurate enough. The ultrasonic nondestructive testing method for measuring the thickness of each layer of the asphalt pavement surface layer utilizes an ultrasonic oblique probe which is used for collecting the echo of each layer of the asphalt pavement surface layer, precisely positions the echo collecting position, and calculates the thickness of asphalt of each layer according to the sound velocity and the corresponding geometric relation by means of a more accurate calculation method for obtaining the arrival time of the echo. The nondestructive, rapid and accurate measurement of the thickness of each layer of the asphalt pavement surface layer is realized.

Inventors

GAO XIANGQIAN
ZHANG QINGQING
WANG GUOQING
HE CHANGZHENG
ZHOU TING
MING YANG
Zu hui
XU WANLI
LI PENGZHEN
SONG FEIFEI
DENG JUNTAO

Assignees

中铁隧道局集团有限公司
河南交投中原高速郑洛建设有限公司
北京华航无线电测量研究所

Dates

Publication Date: 20260508
Application Date: 20241030

Claims (10)

1. An ultrasonic nondestructive testing method for measuring thickness of each layer of an asphalt pavement surface layer is characterized by comprising the following steps: s1, an ultrasonic transmitting probe transmits ultrasonic waves to be obliquely incident on an asphalt pavement at a certain angle theta, the ultrasonic waves are reflected or diffracted in the asphalt pavement layer, and an ultrasonic receiving probe receives ultrasonic signals; S2, adjusting a span PCS between the transmitting probe and the receiving probe so that the receiving probe can receive the reflected echoes of the main sound beam of the transmitting probe at each layer interface in the asphalt pavement surface layer to obtain an echo arrival time t; S3, calculating the asphalt thickness H of each layer according to the following formula according to the sound velocity v and the corresponding geometric relation: Wherein H is the thickness of asphalt in mm, t is the arrival time of echo in mu s, v is the sound velocity in m/s, PCS is the span between the transmitting probe and the receiving probe in mm.
2. The detection method according to claim 1, wherein the asphalt pavement surface layer comprises a surface layer, an upper layer and a lower layer from top to bottom, wherein the target thickness h of the surface layer, the upper layer and the lower layer is h 1 、h 2 、h 3 , the target thickness h 1 is 3-5 cm, the target thickness h 2 is 5-7 cm, and the target thickness h 3 is 7-9 cm.
3. The method according to claim 1, wherein in S1, θ is an oblique incidence angle of the ultrasonic wave, satisfying
4. The detection method according to claim 3, wherein the tan θ is in a range of 1 to 2.
5. The method according to claim 1, wherein in S2, when adjusting the span PCS between the transmitting probe and the receiving probe, the value D of PCS is estimated based on the target thickness h and the oblique incidence angle θ, and the actual value D of PCS is determined by adjusting the value d=2h×tan θ within the error range of D.
6. The method of claim 5, wherein the error range of D is 5%.
7. The method of claim 5, wherein in S2, the PCS is adjusted once every 2mm until the receiving probe can receive the reflected echo of the main beam of the transmitting probe at the asphalt pavement interface.
8. The detection method according to claim 1, wherein in S1, the frequency of the ultrasonic wave emitted by the ultrasonic emission probe is 50-200 khz.
9. The method according to claim 1, wherein in S2, the echo arrival time t is obtained by the following method, comprising the steps of: S101, acquiring the envelope of each frame of signal in a certain time by utilizing Hilbert transformation; S102, obtaining an echo arrival time sequence t xl ＝{t 1 ,t 2 ,…,t m of each frame of signal by an envelope extremum method; S103, clustering the time sequence t xl by using a clustering algorithm to obtain a time center t c ＝{t c1 ,t c2 ,…,t cn of each class; S104, calculating the weight W i of each class of time centers to be equal to the number of elements in the class divided by the total number m of elements, namely: Wherein n i is the number of elements in a class; S105, calculating the arrival time of the echo, which is equal to the time center of each type multiplied by the weight of the echo, and summing, namely:
10. The method according to claim 9, wherein m is equal to or greater than 100, and n is equal to or greater than 10 and equal to or less than 20.

Description

Ultrasonic nondestructive testing method for measuring thickness of each layer of asphalt pavement surface layer Technical Field The invention relates to the technical field of asphalt pavement thickness measurement, in particular to an ultrasonic nondestructive testing method for measuring thickness of each layer of an asphalt pavement surface layer. Background Asphalt pavement is generally composed of a multi-layer structure consisting essentially of a base layer, a sub-base layer, an intermediate layer, and an uppermost surface layer. Among them, the surface layer is usually composed of fine-grained asphalt concrete, and has high wear resistance and skid resistance. The surface layer sequentially comprises a surface layer, an upper surface layer and a lower surface layer from top to bottom, wherein the common thickness is 3-5 cm, 5-7 cm and 7-9 cm respectively. At present, destructive core drilling sampling methods are mostly adopted for detecting the thickness of each layer of the asphalt pavement, and the methods are labor-consuming, time-consuming, high in cost and low in efficiency, and meanwhile, the pavement structure is damaged. Therefore, pavement detection technologies such as ground penetrating radar technology, image detection technology, ultrasonic detection technology and the like are developed, and the pavement detection technology is simple, convenient, rapid and nondestructive. However, in the thickness measurement of each layer in the asphalt surface layer, since the dielectric constants of each layer differ little or no from each other, and each layer is thinner, a higher thickness measurement accuracy is required. The ultrasonic detection technology with stronger layering thickness measurement capability and thickness measurement precision has obvious advantages compared with other technologies. However, on the one hand, the ultrasonic detection technology is greatly influenced by the material property and the internal structure, and the porosity, viscoelasticity and the like of asphalt concrete can influence the propagation and reflection of ultrasonic waves, so that the signal receiving position of reflected waves is difficult to accurately position. On the other hand, the high-sound attenuation asphalt pavement needs to adopt low-frequency ultrasonic detection, which can lead to the jumping of the arrival time of the echo signal in a certain time range, but the current acquisition technology of the arrival time of the echo signal, such as a maximum amplitude method, an echo matching method, a hilbert method and the like, is mainly applied to the condition that the signal is relatively stable, and the time cannot be accurately measured for the changed signal. Both of these aspects can adversely affect the thickness measurement accuracy. Disclosure of Invention In view of the above analysis, the embodiment of the invention aims to provide an ultrasonic nondestructive testing method for measuring the thickness of each layer in an asphalt pavement surface layer, which is used for solving the problem that the measurement precision is limited when the existing ultrasonic nondestructive testing is used for measuring the thickness of each layer in the asphalt pavement surface layer. In one aspect, the embodiment of the invention provides an ultrasonic nondestructive testing method for measuring the thickness of each layer of an asphalt pavement surface layer, which comprises the following steps: s1, an ultrasonic transmitting probe transmits ultrasonic waves to be obliquely incident on an asphalt pavement at a certain angle theta, the ultrasonic waves are reflected or diffracted in the asphalt pavement layer, and an ultrasonic receiving probe receives ultrasonic signals; S2, adjusting a span PCS between the transmitting probe and the receiving probe so that the receiving probe can receive the reflected echoes of the main sound beam of the transmitting probe at each layer interface in the asphalt pavement surface layer to obtain an echo arrival time t; S3, calculating the asphalt thickness H of each layer according to the following formula according to the sound velocity v and the corresponding geometric relation: Wherein H is the thickness of asphalt in mm, t is the arrival time of echo in mu s, v is the sound velocity in m/s, PCS is the span between the transmitting probe and the receiving probe in mm. Further, the asphalt pavement surface layer sequentially comprises a surface layer, an upper surface layer and a lower surface layer from top to bottom, wherein the target thickness h of the surface layer is h 1、h2、h3, the target thickness h 1 is 3-5 cm, the target thickness h 2 is 5-7 cm, and the target thickness h 3 is 7-9 cm. Further, θ is an oblique incidence angle of the ultrasonic wave, satisfying Further, the tan θ is in the range of 1 to 2. Further, in S2, when the span PCS between the transmitting probe and the receiving probe is adjusted, the value D of the PCS is estimated accordi