Method for nondestructively detecting highway guard rail upright post basic soil compaction degree by ultrasonic guide wave

Abstract

The invention relates to a method for nondestructively detecting the degree of compaction of foundation earth of a crash barrier post by using ultrasonic guided waves, which belongs to the field of nondestructive detection. The method comprises the following steps: firstly, determining parameters of the crash barrier post before embedding, and calculating the group velocity dispersion curve and the attenuation dispersion curve of the post before embedding the post into the ground; secondly, selecting a detecting frequency from the group velocity dispersion curve, and inputting the detecting frequency into an arbitrary function generator to generate a single-audio signal so as to excite a longitudinal axisymmetric guide wave mode in the post through a power amplifier module, a change-over switch module and a guided wave transceiver element; and thirdly, generating an end face back wave when the guided wave mode barges up against the end of the post, and transmitting the end face back wave to an oscilloscope through the guided wave transceiver element and the change-over switch module. The magnitudes of the end face back waves which are transmitted twice are determined and the guided wave signal attenuation is calculated; and the degree of compaction of the foundation earth can be determined through calculating the value of the attenuation factor. The method has the advantages of no damages to the post and the structure of the foundation earth, quick speed, low detection cost and the like.

Description

technical field [0001] The invention relates to a method for non-destructive testing of foundation soil compaction around a highway guardrail column partially embedded in a roadbed by using ultrasonic guided waves, and belongs to the field of non-destructive testing. Background technique [0002] In order to prevent traffic accidents caused by cars driving on the expressway rushing out of the road or entering the opposite lane of the road, anti-collision guardrails are erected on the roadside and central isolation belt of modern expressways, and the guardrail columns are the main load-carrying parts of the guardrails. part. Due to the complex conditions around the guardrail, it is easy to cause insufficient compaction of the foundation soil around the column during the embedding process, resulting in a decrease in the anti-collision performance of the guardrail column and causing accident hazards to transportation. Since the highway guardrail column is partially buried in t...

AI Technical Summary

Problems solved by technology

Due to the complex conditions around the guardrail, it is easy to cause insufficient compaction of the foundation soil around the column during the embedding process, which will cause the anti-collision performance of the guardrail column to decline, and cause accident hazards to transportation

Since the highway guardrail column is partially buried in the roadbed, its failure mode is very concealed, and it is very difficult to effectively detect it, especially the buried part.

[0003] The national standard currently uses methods such as sand filling method and ring knife method to detect the compaction degree of road subgrade, which will cause a certain degree of damage to the road subgrade. At present, there is no use of ultrasonic guided wave method to detect the compaction degree of guardrail foundation soil. related reports

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