Tunnel lining thickness identification method and system based on ground radar wavelet transform

Abstract

The invention belongs to the technical field of tunnel lining thickness detection, and discloses a tunnel lining thickness identification method and system based on geological radar wavelet transform. According to the characteristics that the reflection and refraction of electromagnetic waves are both in the two-dimensional plane, the geoelectric model of the concrete structure with different thickness of the tunnel lining is established. Using the ground radar antenna to carry out forward modeling simulation of the geoelectric model of the concrete structure with different thicknesses of the tunnel lining; according to the migration algorithm, the characteristic response of the ground radar is migrated; according to the time-frequency characteristics of the wavelet emitted by the ground radar, a Gaussian function is used to fit it Constructing GPR wavelet bases. According to the constructed geological radar wavelet base, the wavelet transform time energy density analysis program is written, and the wavelet transform time energy density method is used to analyze and identify the geological radar forward modeling signal and measured signal, and the thickness value of the tunnel lining concrete structure is obtained. The ground radar signal analyzed by the invention has high resolution, accurate result and small recognition error, which is less than 5% of the design value.

Description

technical field [0001] The invention belongs to the technical field of tunnel lining thickness detection, in particular to a tunnel lining thickness recognition method and system based on geological radar wavelet transform. Background technique [0002] At present, tunnel engineering is one of the key passages, nodes and key control projects of transportation infrastructure construction. As of the end of 2018, China's tunnel construction, including railway tunnels, highway tunnels, and urban rail transit tunnels, totaled 36,103km, with about 20,000km of tunnels under construction and about 20,000km of planned tunnels. During the construction of the tunnel project, due to poor smooth blasting effect on the surrounding rock of the tunnel, non-standard shotcrete construction technology and insufficient pressure of pumped molded concrete, etc., the gap between the surrounding rock and the lining structure and the shotcrete and waterproof board There are often voids and voids be...

AI Technical Summary

Problems solved by technology

[0006] (1) The pre-embedded steel bar method, drilling method and coring method will all damage the integrity of the tunnel lining structure (especially the tunnel waterproof system), and these detection methods are slow and can only sample a few selected sections Inspection, cannot fully guarantee the construction quality of the tunnel lining concrete structure

It is difficult to ensure that the tunnel laser profiler method is erected at the same position, and the measurement error before and after is also relatively large, which not only increases the workload of the inspectors, but also affects the construction progress in the limited working space of the tunnel

[0007] (2) When the geological radar method is used to identify the thickness of the reinforced concrete lining, the steel bars in the reinforced concrete lining of the tunnel strongly interfere with the detection of geological radar electromagnetic waves, resulting in rapid attenuation of electromagnetic wave energy, which makes the deep secondary lining concrete and shotcrete, shotcrete and enclosure The electromagnetic wave reflection signal at the reflection interface between the rocks is weak, and it is difficult to obtain the thickness of the reinforced concrete structure by using the geological radar profile method

[0008] (3) When the relative permittivity of the molded concrete lining is lower than that of the shotcrete lining, and the relative permittivity of the shotcrete lining is greater than that of the surrounding rock, the electromagnetic waves will have phase inversion at each interface. phase, but the instantaneous position of the reflected wave generated by the electromagnetic wave encountering the interface cannot be identified from the geological radar time section

[0009] The difficulty in solving the above problems and defects is that it is difficult to accurately identify the interface position between lining concrete and shotcrete, shotcrete and surrounding rock only by the peak and amplitude changes on the geological radar profile, and due to the strong interference of steel bars on electromagnetic waves, It greatly increases the difficulty of weak signal processing at the deep interface

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