CN205655803U - Soil deformation distributed optical fiber monitoring is markd and test device - Google Patents

Abstract

The utility model relates to a soil deformation distributed optical fiber monitoring is markd and test device, including maring and experimental main tank, the sensing optical fiber of meeting an emergency, optical demodulation, image processing and analytical equipment, the two sides is transparent rigid slab, the inside soil body that has the compaction in layers of filling around the experimental main tank, the sensing optical fiber of meeting an emergency along the level to and/or vertically lay in the soil body piecemeal, optical demodulation is connected with the sensing optical fiber of meeting an emergency and gathers the inside strain data of the soil body, image processing and analytical equipment be used for measuring around with transparent rigid slab contact the soil body the displacement with meet an emergency. The utility model discloses interact and deformation coupling nature between the research soil body and the optic fibre can be markd to soil deformation's distributed optical fiber monitoring reading to acquire the space -time evolution law that internal portion meets an emergency of burying at different work condition such as loading, uninstallation, excavation, seepage flow.

Description

Soil deformation distributed optical fiber monitoring calibration and test device

technical field

The utility model relates to the technical field of soil deformation and distributed optical fiber monitoring engineering, in particular to a distributed optical fiber monitoring calibration and test device for soil deformation.

Background technique

The deformation of soil is an important index to evaluate the stable state of soil. For some large-scale projects such as slope filling, dam construction and tunnel excavation, the implementation of distributed deformation monitoring will help to obtain the abnormal parts of soil stress and deformation in time, and take corresponding engineering countermeasures to ensure the normal construction and operation of the project . Existing non-contact soil deformation measurement technologies, such as global positioning system, remote sensing, laser scanning, and photogrammetry, can only obtain deformation information on the soil surface, and their measurement accuracy is usually not high. Although rock and soil monitoring instruments such as slope inclinometers and borehole extensometers can measure the internal deformation of the soil in engineering, it is difficult to implement remote, real-time and long-term monitoring, and the measurement distance and range are usually not large. There are monitoring blind spots.

In recent years, distributed optical fiber monitoring technology has developed rapidly, and its application in soil deformation monitoring is also increasing. With the help of monitoring technologies such as quasi-distributed fiber Bragg grating (FBG), fully distributed Brillouin optical time-domain reflectometry (BOTDR) and Brillouin optical time-domain analysis (BOTDA), the strain, Distribution of monitoring information such as temperature. Compared with traditional monitoring methods, distributed optical fiber monitoring has the advantages of large data collection, small sampling interval, high accuracy of results, and is suitable for long-distance monitoring. Therefore, it has broad application prospects in the field of soil deformation measurement. Recently, some researchers at home and abroad directly embed the strain sensing optical fiber in the soil to be monitored, and analyze the deformation state and stability of the soil based on the optical fiber sensing data. This method is relatively convenient for construction, but the interaction mechanism and coordinated deformation between the soil and the strain sensing optical fiber have not been fully understood, and there is no scientific basis for the selection of the strain sensing optical fiber and the setting of the anchor point. The reliability of optical fiber monitoring results has great uncertainty, which greatly restricts the popularization and application of this technology in engineering.

Contents of the invention

Aiming at the deficiencies of the prior art, the purpose of the utility model is to provide a distributed optical fiber monitoring calibration and testing device for soil deformation.

The utility model adopts the following technical solutions: a distributed optical fiber monitoring calibration and testing device for soil deformation, including a calibration and testing main box, a strain sensing optical fiber, an optical fiber demodulator, and a digital image acquisition and analysis device; the calibration The front and rear sides of the test main box are provided with transparent rigid plates, and the other two side plates are rigid plates filled with layered and compacted soil. The strain sensing optical fiber is gradually The section is laid in the soil, the front and rear transparent rigid plates are provided with marking points around the corresponding strain sensing optical fiber, and the soil is also provided with a pressure device; the optical fiber demodulator and the strain sensing optical fiber connection; the digital image acquisition and analysis device is arranged at the front and back of the calibration and test main box; the strain sensing optical fiber is provided with a strain sensing sensor.

The rigid side plate is provided with a fiber penetration hole.

The digital image acquisition and analysis device includes a high pixel digital camera and a computer.

The pressurizing device includes a loading plate and weights or jacks.

Beneficial effect: adopting the soil deformation optical fiber monitoring calibration and test device of the utility model patent, the digital image acquisition and analysis device can be used to calibrate the readings of soil deformation optical fiber monitoring, and on this basis, the interaction mechanism between soil and optical fiber can be studied and deformation coupling, and obtain the spatio-temporal evolution law of the internal strain distribution of the soil under different working conditions such as loading, unloading, excavation, and seepage.

Description of drawings

Fig. 1 is a schematic structural view (front view) of an embodiment of the present invention.

Fig. 2 is a schematic structural view (section 1-1) of an embodiment of the present invention.

Fig. 3 is a nephogram of the horizontal linear strain of the side wall soil mass measured by using the method of an example of the present invention.

Fig. 4 is a comparison chart of the soil optical fiber strain value measured by using the method of an example of the present invention and the digital image processing result.

Fig. 5 is the calibration result of optical fiber strain data by using the method of an example of the present invention.

Fig. 6 is a strain-time distribution diagram of different parts of the soil under different loads measured by using the method of an example of the present invention.

detailed description

Below in conjunction with accompanying drawing and preferred embodiment the utility model is described more specifically.

A distributed optical fiber monitoring calibration and testing device for soil deformation, including a calibration and testing main box, a strain sensing optical fiber, an optical fiber demodulator, and a digital image acquisition and analysis device; the front and rear sides of the calibration and testing main box are transparent Rigid board, the other two side boards are rigid boards, filled with layered and compacted soil; the strain sensing optical fiber is laid horizontally and/or vertically in the soil segment by section; the optical fiber demodulation The instrument is connected to the strain sensing optical fiber and collects the strain data inside the soil; the digital image acquisition and analysis device is used to measure the displacement and strain of the soil in contact with the front and rear transparent rigid plates, and to calibrate the strain data of the optical fiber.

As a further optimization of the above scheme, the two rigid side plates of the calibration and test main box have a number of small holes for passing through the optical fibers arranged horizontally, and a number of paper circular marking points are pasted on the outside of the two transparent rigid plates.

Further, the digital image acquisition and analysis device also includes:

(1) Paper circular marking points; the paper circular marking points are pasted on the outside of the two transparent rigid plates at a certain interval;

(2) two high-pixel cameras; the two high-pixel cameras are respectively placed on the sides of the two transparent rigid plates, and photograph the soil body in contact with the transparent rigid plates;

(3) Digital image processing software; the digital image processing software is based on Digital Image Correlation (DIC for short) or Particle Image Velocimetry (PIV for short).

(4) Optical fiber strain calibration program; the optical fiber strain calibration program adopts the strain data obtained by digital image processing to calibrate the optical fiber strain data by ε _FOS = ζε _DIP , wherein ε _DIP is the strain data obtained by digital image processing, and ε _FOS is the optical fiber measurement The obtained strain data, ζ is the calibration coefficient.

Example

As shown in Figure 1 and Figure 2, a soil deformation optical fiber monitoring calibration and testing device, it includes calibration and testing main box, strain sensing optical fiber, optical fiber demodulator, digital image acquisition and analysis device; The front and rear sides of the test main box are transparent rigid plates, and the other two side plates are rigid plates filled with layered and compacted soil; the strain sensing optical fiber is laid horizontally and/or vertically on the soil In the body; the optical fiber demodulator is connected to the strain sensing optical fiber and collects strain data inside the soil; the digital image acquisition and analysis device is used to measure the displacement and strain of the soil in contact with the front and rear transparent rigid plates.

The two rigid side plates of the calibration and test main box have a number of small holes for passing through the optical fibers arranged horizontally, and a number of paper circular marking points are pasted on the outside of the two transparent rigid plates. The digital image acquisition and analysis device also includes: (1) paper circular marking points; the paper circular marking points are pasted on the outside of the two transparent rigid boards at a certain interval; (2) two high-pixel cameras; The two high-pixel cameras are respectively placed on the sides of the two transparent rigid plates, and photograph the soil body in contact with the transparent rigid plates; (3) digital image processing software; the digital image processing software is based on digital image coherence method or particle image velocimetry method, etc.; (4) Optical fiber strain calibration program; the optical fiber strain calibration program uses digital image processing to calibrate the optical fiber strain data according to ε _FOS = ζε _DIP , wherein ε _DIP is the strain data obtained from digital image processing, and ε _FOS is the strain data measured by the optical fiber, and ζ is the calibration coefficient.

The test method of the above-mentioned soil deformation optical fiber monitoring calibration and test device provided in this embodiment includes the following steps:

1) Paste paper circular marking points on the front and rear transparent rigid plates of the model box at certain intervals;

2) Prepare the soil samples for the test, and fill the foundation model layer by layer in the calibration and test main box by using the falling sand method or the compaction method;

3) When the ground is filled to the location where the strain-sensing optical fiber is laid, the strain-sensing optical fiber is pre-tensioned to a certain strain and laid in the soil;

4) After all the strain sensing optical fibers are laid, connect all the optical fibers to each other in parallel or in series, and use the transmission optical fiber to connect to the interface of the optical fiber demodulator. After the test starts, the optical fiber interrogator reads continuously;

5) Place a loading plate in the center of the surface of the filled foundation model, and use weights or jacks to apply loads in stages after the test starts;

6) Place two high-resolution digital cameras on both sides of the transparent rigid plate, and take continuous photos of the soil in contact with the transparent rigid plate after the test starts;

7) Use digital image processing software to analyze a series of photos taken by a high-resolution digital camera, compare the obtained soil strain results with the optical fiber monitoring results, and use the optical fiber strain calibration program to calibrate the optical fiber strain data.

When the soil deformation optical fiber monitoring calibration and test device of this embodiment is used in practice, the sandy soil with a moisture content of 4% is first passed through a 2mm sieve, and then the sand falling method is used in the calibration and test main box (size length × width × A sand foundation model (average density 1.47g/cm ³ , relative compactness 0.248) is filled in a height of 50cm×25cm×50cm). Three strain-sensing optical fibers are installed in layers inside the sand foundation model, with a vertical spacing of 3.3 cm, and three FBG strain-sensing sensors are connected in series on each optical fiber, with a sensor spacing of 10 cm. The number of the FBG sensor in the middle of each strain sensing fiber is 2, and the two sides are marked as 1 and 3. Connect the 3 strain sensing optical fibers (marked as H1, H2, H3 from top to bottom) to the FBG fiber optic interrogator respectively, and automatically collect readings. Of course, it is also possible to set two strain sensing optical fibers vertically to the ground in the same manner, denoted as V1 and V2, and connected to the FBG optical fiber demodulator. Paste 3 layers of paper circular markers at 10cm intervals on the front and rear transparent rigid plates of the model box. After the filling of the foundation model is completed, a 10cm×25cm×1cm aluminum plate is placed in the center as a loading plate, and then a static load is applied with weights. A total of three levels of load were applied in the test, and the load increments were 4kPa, 8kPa, and 8kPa, respectively. Every time a load is applied, a Canon EOS 600D digital camera is used to take continuous pictures outside the front and rear walls of the model box. The photographs obtained were analyzed by PIV digital image processing software, and the horizontal line strain nephogram of the side wall soil was obtained, as shown in Figure 3. Comparing and analyzing the soil strain obtained by FBG monitoring and the soil strain at the corresponding point of the side wall obtained by digital image processing, the FBG optical fiber monitoring results can be calibrated, as shown in Figure 4 and Figure 5. In this embodiment, the optical fiber strain calibration coefficient ζ=0.705. At the same time, the FBG also monitored the strain time history curves of different parts of the sand foundation model under various loads, as shown in Figure 6.

It should be noted that, in addition to the above-mentioned embodiments, the utility model patent may also have other implementation modes. All technical solutions formed by equivalent replacement or equivalent transformation fall within the scope of protection required by the utility model patent.

Claims (4)

1. A soil deformation distributed optical fiber monitoring calibration and test device is characterized in that it includes calibration and test main box, strain sensing optical fiber, optical fiber demodulator, digital image acquisition and analysis device; said calibration and test main box The front and rear sides of the box are provided with transparent rigid boards, and the other two side boards are rigid boards filled with layered and compacted soil. The strain sensing optical fiber is laid on the In the soil, marking points are provided around the corresponding strain sensing optical fiber on the front and rear transparent rigid plates, and a pressure device is also provided on the soil; the optical fiber demodulator is connected to the strain sensing optical fiber; The digital image acquisition and analysis device is arranged before and after the calibration and test main box; the strain sensing optical fiber is provided with a strain sensing sensor. 2 . The distributed optical fiber monitoring calibration and testing device for soil deformation according to claim 1 , wherein the rigid side plate is provided with an optical fiber penetration hole. 3 . 3. The distributed optical fiber monitoring calibration and testing device for soil deformation according to claim 1, wherein the digital image acquisition and analysis device includes a high-pixel digital camera and a computer. 4. The soil deformation distributed optical fiber monitoring calibration and test device according to claim 1, characterized in that, the pressurizing device includes a loading plate and a weight or a jack.