Point heat source mobile distributed seepage monitoring system and monitoring method thereof

Abstract

The invention discloses a point heat source mobile distributed seepage monitoring system and a monitoring method thereof. The monitoring system comprises a sensing heating element, a monitoring tube,a voltage-stabilized source, a fiber grating demodulator, a notebook computer, an armored cable and a wire. Sensing elements in the sensing heating element are connected in series by the armored cable; the armored cable is connected with the fiber grating demodulator; and multi-measuring-point synchronous measurement is carried out by using a wavelength division multiplexing technology. The fibergrating demodulator is connected with the notebook computer. The sensing elements in the sensing heating element are connected in series by the wire; and the two ends of the wire are connected with the voltage-stabilized source to form a closed loop for electrification and heating. The sensing heating element penetrates the monitoring tube. The point heat source mobile distributed seepage monitoring system has the advantages: with construction of the point heat source heating system, the influence on the seepage monitoring result by the seepage direction can be eliminated; a spatial resolutionproblem of the fiber grating quasi-distributed sensing system is solved by mobile distributed monitoring; and the monitoring line can be taken out from the monitoring tube to carry out repairing or replacement.

Description

technical field [0001] The invention relates to the technical field of geotechnical engineering seepage monitoring, in particular to an optical fiber grating point heat source moving distributed seepage monitoring system and a monitoring method thereof. Background technique [0002] Seepage problems exist in many geotechnical projects. Seepage will affect the stability of rock and soil mass and directly threaten the safety of the project. The well-known failure of the Teton Dam in the United States was caused by seepage damage. [1] . Seepage is concealed, random in space and time, and most of the prevention and control of seepage needs to be supplemented by certain monitoring methods. Therefore, seepage monitoring is an important monitoring content in the field of geotechnical engineering. [0003] Seepage monitoring methods are diverse, including: (1) Conventional monitoring methods. This type of method has a long history, with many engineering applications and experience...

AI Technical Summary

Problems solved by technology

[0007] (1) This technology uses a distributed optical fiber temperature measurement system based on Raman scattering, which has a low spatial resolution of about 1m, and the measured temperature is the average temperature within a range of 1m, with low accuracy;

[0008] (2) The heating method adopts resistance wire heating. The monitoring line of the earth-rock dam is long, and the resistance value of the resistance wire matched with the monitoring line is relatively large. To reach the predetermined heating temperature, a higher voltage and a longer heating time are often required ;

[0009] (3) The resistance value of the resistance wire will change with the change of temperature, therefore, it is difficult to ensure the stability of the heating power;

[0010] (4) There is a hidden danger of electric leakage when the cable is buried in wet soil for a long time;

[0011] (5) The heat source in the monitoring system is a linear heat source, which cannot eliminate the influence of the seepage direction on the monitoring results

This technology directly penetrates the fiber grating sensing string into the heating pipeline, and the two ends are sealed with hot melt adhesive. The position of the measuring point is fixed, but the position of the seepage is uncertain. When there is no measuring point near the seepage area , it will affect the identification accuracy of the seepage state

The monitoring range of earth-rock dams is large. To ensure spatial resolution and avoid missed judgments, it is necessary to increase the number of measuring points, thereby increasing monitoring costs.

[0016] (2) As the length of the monitoring line increases, the heating effect will weaken, thereby affecting the monitoring accuracy

[0017] (3) The heat source in the monitoring system is a linear heat source, which cannot eliminate the influence of the seepage direction on the monitoring results

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