An optical fiber ground stress measurement system

Abstract

The invention discloses an optical fiber ground stress measurement system, which belongs to the fields of crustal deformation observation, earthquake monitoring and forecasting in geophysics, and comprises a sensing optical fiber, a reference optical fiber, a ground stress transmission unit and a signal processing unit; the ground stress transmission unit is fixed on In the bedrock, the sensing fiber is wound between the ground stress transmission units and the prestress can be adjusted to adjust its sensitivity; when the bedrock causes relative displacement due to ground stress, the ground stress transmission unit transmits the ground stress signal to the sensor The optical fiber causes the stress change of the sensing fiber; the signal processing unit calculates the phase change difference of the Rayleigh backscattered light of the sensing fiber and the reference fiber, and obtains the ground stress information at the bedrock position. The present invention adopts micro-structure point high-scattering-rate optical fiber as the sensitive unit, combines the sensitivity-increasing installation method and the temperature compensation algorithm, and can realize the high-precision ground stress detection with short baseline through the phase demodulation system, cascades through multiple units, and uses a The root fiber realizes distributed real-time detection.

Description

technical field [0001] The invention belongs to the field of crustal deformation observation, earthquake monitoring and forecasting in geophysics, and more specifically relates to an optical fiber ground stress measurement system. Background technique [0002] Crustal deformation observation is one of the core links in the study of geological tectonic processes and geological disasters such as earthquakes and volcanoes in geophysics, and it is also the basis for the study of geomechanics. Compared with general application scenarios, the strain signal to be observed in the geological structure process is extremely weak, and the sources of interference are complex, which accordingly puts forward higher requirements for sensing and measurement technology. Indium steel rod telescopic strain gauge technology is widely used in traditional crustal strain monitoring stations. In order to achieve nano-strain level measurement resolution, the length of the sensing probe must reach ten...

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Problems solved by technology

[0005] In view of the above defects or improvement needs of the prior art, the present invention provides an optical fiber ground stress measurement system, the purpose of which is to fix the system on the bedrock and sense the ground strain on the sensing optical fiber through the ground stress transfer unit , the sensing fiber is subjected to strain to produce a phase change, and the ground stress information can be obtained by demodulating the phase change, thereby solving the technical problem of high complexity in the construction of the existing electrical geodesic extensometer

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