Subsoil 3D Imaging via Mobile Seismic Noise Interferometry
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Solution Overview
Problem
Existing seismic monitoring methods for subsoil anomalies, such as cavity detection under infrastructure, are limited to two-dimensional imaging and suffer from low signal quality due to ambient noise interference, failing to provide instantaneous and reliable three-dimensional imaging.
Innovation Solution
A method involving seismic wave sensors arranged on either side of a target area, using a mobile seismic noise source aligned with the sensors to record and reconstruct seismograms, which are then preprocessed for optimal quality, allowing for four-dimensional passive monitoring of the subsoil, enabling three-dimensional imaging through the movement of the source.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If a single line of seismic wave receivers is deployed along the railway track using ambient noise interferometry, then the monitoring coverage is established, but the imaging is limited to two-dimensional and does not provide three-dimensional subsoil image
Solution Approach 1:
The patent transitions from 2D imaging to 3D imaging by deploying sensors in multiple lines (at least two parallel lines) rather than a single line, and by utilizing a mobile noise source that moves along the track to provide signals from multiple positions, thereby reconstructing three-dimensional subsoil structure
Solution Approach 2:
The patent employs a mobile seismic noise source (such as a train) that moves along the railway track, dynamically changing its position relative to the sensor array. This movement allows the system to collect seismic signals from multiple source positions, enabling three-dimensional reconstruction of the subsoil beneath the target area
2Reliability
If purely passive ambient noise is used for interferometry, then the method is simple to implement, but the signal quality is low due to mixed noise and the noise source is far from receivers
Solution Approach 1:
The patent converts the mobile train, which produces seismic noise considered as interference, into a beneficial identified noise source. By selecting trains with known characteristics and trajectories, the system uses their seismic signals as intentional sources for interferometry, thereby improving signal quality while maintaining the passive nature of the receiver system
Solution Approach 2:
The patent introduces an identified mobile noise source (train) as an intermediary between the ambient environment and the receivers. This intermediary provides structured, traceable seismic signals that can be correlated with receiver positions and times, enabling better signal separation and quality improvement compared to unstructured ambient noise
3Measurement precision
If trains on the same track as the target area are used as noise sources, then the alignment with sensors is achieved, but the infrastructure safety is compromised by requiring trains to pass over the area to be studied
Solution Approach 1:
The patent segments the railway system into separate functional zones: a source track for mobile noise generation and a target track for monitoring. By dividing the railway infrastructure into distinct segments with different functions, the system achieves sensor-source alignment for precise measurement while eliminating the safety risk of requiring trains to pass over the area being studied
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach provides high-resolution, large-amplitude, and reliable three-dimensional imaging of the subsoil, enhancing the detection of anomalies and ensuring safety of terrestrial infrastructure by improving signal quality and reducing noise interference.
Implementation Method 1
recording seismic waves coming from a mobile source of seismic noise
Implementation Method 2
reconstructing a seismogram of the target area from these recordings by interferometry
Data Source
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AI summary
In order to monitor the subsoil of the earth under a target zone (3), seismic waves from an identified mobile noise source (24) are recorded by means of at least one pair of sensors (22) arranged on either side of the target zone (3), time periods corresponding to the alignments of the pairs of sensors (22) with the noise source (24) are selected, a seismogram of the target zone (3) is reconstructed by interferometry from the seismic waves recorded and the selected time periods, and an image of the subsoil of the target zone (3) is generated from the seismogram.