UWB Radar Technologies for Tunnel Detection

Dr. Sergey BondarenkoDr. Sergey BondarenkoEmail: [email protected]: [email protected]

The main difference between the approaches is object primary registration method. The The main difference between the approaches is object primary registration method. The first is based on wave reflection only, the second one can also use wave attenuationfirst is based on wave reflection only, the second one can also use wave attenuation

It follows surface units are unburied or slightly buried in contrast to borehole unitsIt follows surface units are unburied or slightly buried in contrast to borehole units However cross borehole techniques provide twice more underground space observation However cross borehole techniques provide twice more underground space observation

with equal system dynamic range for the both radarswith equal system dynamic range for the both radars Generally the both techniques allow computer tomography data processing and have Generally the both techniques allow computer tomography data processing and have

similar topography and differ only “borehole deepness”similar topography and differ only “borehole deepness” The most important part of UWB radar is RF unit especially buried wideband The most important part of UWB radar is RF unit especially buried wideband

antennaantenna

The most important process is energy accumulation: on the transmitter side (a The most important process is energy accumulation: on the transmitter side (a few MW in a short pulse like GPR “Loza”) or on the receiver side (stepped few MW in a short pulse like GPR “Loza”) or on the receiver side (stepped frequency continuous wave (SFCW) like 3d-Radar MARA Nord)frequency continuous wave (SFCW) like 3d-Radar MARA Nord)

Nowadays the both technologies are intensively developed for different applications Nowadays the both technologies are intensively developed for different applications (see, for example, LWD Borehole Radar presentation)(see, for example, LWD Borehole Radar presentation)

Under “unlimited processing time” SFCW approach becomes more attractive Under “unlimited processing time” SFCW approach becomes more attractive allowing to use both pulse synthesis method and multi-frequency phase allowing to use both pulse synthesis method and multi-frequency phase processing method.processing method.

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Direct Synthesis

Synthesis by Weighted Processing

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f=1000 МГц f=100 МГц

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UWB Surface Based Radar Technology UWB Surface Based Radar Technology for Tunnel Detection (Square Monitoring)for Tunnel Detection (Square Monitoring)

Transmitters (Tx) radiate power into the ground. Receivers (Rx) collect the received field and send the information Transmitters (Tx) radiate power into the ground. Receivers (Rx) collect the received field and send the information to the main station at a drone for tomography processing. Due to option of one way propagation mode and the to the main station at a drone for tomography processing. Due to option of one way propagation mode and the object primary registration method based on wave attenuation in addition to wave reflection the distances object primary registration method based on wave attenuation in addition to wave reflection the distances between transmitters and receivers can be a big enough (tens or hundreds meters depending on ground between transmitters and receivers can be a big enough (tens or hundreds meters depending on ground parameters).parameters).

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UWB Borehole Radar Technology UWB Borehole Radar Technology for Tunnel Detection (Borderline Monitoring 1)for Tunnel Detection (Borderline Monitoring 1)

Ground Penetrating Radar (GPR) methodology. Transmitter (Tx) of the transceiver unit radiates power Ground Penetrating Radar (GPR) methodology. Transmitter (Tx) of the transceiver unit radiates power driving along the borderline into the horizontal borehole. Receiver (Rx) of the unit collects the driving along the borderline into the horizontal borehole. Receiver (Rx) of the unit collects the scattered field during the drive and produces D-scan.scattered field during the drive and produces D-scan.

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UWB Borehole Radar Technology UWB Borehole Radar Technology for Tunnel Detection (Borderline Monitoring 2)for Tunnel Detection (Borderline Monitoring 2)

A few vertical boreholes along borderline are used. Transmitter radiates power (Tx) driving into a one A few vertical boreholes along borderline are used. Transmitter radiates power (Tx) driving into a one borehole. Receiver (Rx) collects the penetration field during the drive into the other borehole. borehole. Receiver (Rx) collects the penetration field during the drive into the other borehole. Collected information is used for tomography processing. Collected information is used for tomography processing.

Penetration field

TunnelTunnel

The main advantage of the radar method is a high constant difference of The main advantage of the radar method is a high constant difference of the permittivity between tunnel ( the permittivity between tunnel ( εεrr ≈ ≈ 1 1 ) and around space ( ) and around space ( εεrr ≥ ≥ 4-6 4-6 ) for ) for use of the reflective method on a one hand and significant tunnel width use of the reflective method on a one hand and significant tunnel width ((more than 2 metersmore than 2 meters) for use of the attenuation method on the other) for use of the attenuation method on the other

Nowadays there is a good opportunity to gather three well developed Nowadays there is a good opportunity to gather three well developed techniques, namely, tomography reconstruction, UWB radar (GPR) and techniques, namely, tomography reconstruction, UWB radar (GPR) and digital direct synthesizer (DDS) to successfully solve tunnel detection digital direct synthesizer (DDS) to successfully solve tunnel detection problemproblem

At last, combination acoustic (“hammer”) and UWB radar methods is At last, combination acoustic (“hammer”) and UWB radar methods is reasonablereasonable

There are many complete or good verified independent results in all these There are many complete or good verified independent results in all these fields fields

The mainstream is right coordination of independent research and The mainstream is right coordination of independent research and technological resources.technological resources.

Thank you for attention.Thank you for attention.

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