CN107083993B - The Embedment and installation structure and installation method of Safety Monitoring Instruments in the long tunnel of high water head - Google Patents

Abstract

The invention discloses a buried installation structure of a safety monitoring instrument in a long tunnel with high water head and a specific installation method thereof. The buried installation structure includes a plurality of buried installation units in tunnel monitoring sections, and the buried installation units in the tunnel monitoring section include temporary protection wooden boxes and Several fiber grating monitoring instruments, each fiber grating monitoring instrument is connected with a cable, the temporary protective wooden box is trapezoidal, the top has an openable cover, and one side has a slope suitable for the side of the long canal in the tunnel, and the box is provided with There are openings through which the cables connected by each fiber grating monitoring instrument are introduced into the temporary protective wooden box, and the cables are used to connect the temporary optical cables or the main transmission optical cables. The solution of the invention can effectively protect the tail cable of the monitoring instrument, improve the integrity rate of the instrument burial and the integrity of the monitoring data, and try not to repeat the wavelength measurement value of the fiber grating instrument on the same monitoring section, thereby improving the system wavelength division multiplexing efficiency.

Description

Buried installation structure and installation method of safety monitoring instrument in long tunnel with high water head

technical field

The invention belongs to the technical field of geotechnical engineering safety monitoring, and in particular relates to a buried installation structure of a safety monitoring instrument in a long tunnel with high water head and an installation method thereof.

Background technique

In geotechnical engineering, safety monitoring instruments must be installed to monitor all aspects of the site, so as to give early warning in case of abnormality and take corresponding measures in time. Safety monitoring instruments such as rebar gauges, strain gauges, and piezometers generally use differential resistance, vibrating wire and other electrical sensors. In recent years, with the implementation of long-distance water transfer projects and the development of fiber Bragg grating sensing and demodulation technology, sensors based on Fiber Bragg Grating (FBG) have been gradually applied in water diversion projects. Grating instruments have the advantages of long-distance signal transmission, flexible networking, anti-electromagnetic interference, and low insulation requirements.

The installation of monitoring instruments in tunnel construction has always been a difficult point in construction, because the tunnel distance is long, the space is small, and the construction is relatively extensive, which makes the installation and protection of safety monitoring instruments in tunnel construction more difficult than other projects, and even It is impossible to install at all, and sometimes even if it is installed in place, it is easy to cause damage to the monitoring equipment during the tunnel pouring process. Moreover, the data during the tunnel lining pouring process cannot be collected at all.

SUMMARY OF THE INVENTION

In order to solve the above problems, the present invention discloses a buried installation structure of a safety monitoring instrument in a long tunnel with high water head and a specific installation method thereof, which can realize the fast and stable installation of the safety monitoring instrument in the long tunnel.

In order to achieve the above object, the present invention provides the following technical solutions:

The method for burying and installing safety monitoring instruments in long tunnels with high water head includes the following steps:

Step 1: After the excavation and clearing of the foundation are completed, start to bind the steel bars. Before the steel bars are bound, the formwork trolley tracks are installed in the warehouse synchronously. At the same time, the formwork trolleys are assembled at the concrete position of the adjacent warehouse, and the upper edge of the steel bars on the monitoring section is monitored in the same tunnel. A plurality of fiber grating monitoring instruments are installed in the circumferential direction, and a temporary protective wooden box that is easy to remove is fixed on the steel reinforcement at the bottom of the tunnel. ;

Step 2: After the monitoring instrument pigtail cable enters the temporary protective wooden box, connect these pigtail cables one by one, and seal the gap between the opening of the protective wooden box and the cable with expanded foam to prevent the entry of concrete mortar;

Step 3: Connect each fiber grating monitoring instrument in series with the temporary optical cable leading to the lower warehouse concrete, and use a portable fiber grating demodulator to test whether the wavelengths of all the connected monitoring instruments can be collected normally. If the wavelengths overlap, adjust the string. connection method until normal measurement;

Step 4: The formwork trolley is moved into the concrete pouring site along the track in the axial direction of the tunnel. After each work is completed, the formwork trolley is unfolded, and the other special-shaped parts are sealed with wooden molds and then poured into concrete. After the formwork trolley enters the warehouse surface When pouring concrete, measure according to the required data collection frequency;

Step 5, after the concrete completes the initial setting, remove the formwork trolley, dig out the pre-embedded protective wooden box, and directly collect data one by one at the inverted arch part of the monitoring section, which is connected to the outgoing tail cable of the instrument;

Step 6: After the lining construction is completed, remove the temporary protective wooden box and take it out, install the optical cable splicing protection box in the space left by the temporary protective wooden box in the lining, connect the fiber grating monitoring instruments in series or in parallel and then spliced to the main optical cable. , and finally backfill with concrete after the commissioning is completed.

Further, the wavelength measurement values of the fiber grating instruments in the same group of the same monitoring section are not repeated.

Further, the fiber grating monitoring instrument is provided with at least one grating, and when two or more gratings are provided, a buffer zone of 0.5 nm is set between every two gratings.

Further, in the second step, the number of series connected sensors is less than 5 sensors or 10 wavelengths.

The buried installation structure of safety monitoring instruments in long tunnels with high water head includes several buried installation units in tunnel monitoring sections, and the buried installation units in tunnel monitoring sections include temporary protection wooden boxes and several fiber grating monitoring instruments buried on the circumference of the same tunnel monitoring section , each fiber grating monitoring instrument is connected with a pigtail cable, and each fiber grating instrument is connected in series or in parallel with each other, the temporary protection wooden box is trapezoidal, the top has an openable cover, and one side has a long canal in the tunnel. The box is provided with an opening on the inclined plane, and the cables connected by each fiber grating monitoring instrument are introduced into the temporary protective wooden box through the opening, and the cables are used to connect the temporary optical cable or the main transmission optical cable.

Further, the cable jacket is provided with a protective tube.

Further, the protection tube is a PE tube.

Further, the temporary protection wooden box is embedded in the platform at the bottom of the tunnel, and the height of its top surface is less than or equal to the height of the top surface of the platform.

Further, the opening is provided on the bottom surface of the protection box.

Further, each fiber grating monitoring instrument in the buried installation unit of the same tunnel section is connected in series through the flange for observation during the construction period.

Compared with the prior art, the present invention has the following advantages and beneficial effects:

1. Effectively protect the tail cable of the monitoring instrument, improve the burial integrity rate of the instrument, and collect the monitoring data during the period after the lining is poured and the formwork trolley is removed, which improves the integrity of the monitoring data and accurately obtains the reference value. The accuracy of subsequent data monitoring is greatly improved.

2. The wavelength measurement value of the fiber grating instrument of the same monitoring section should not be repeated as much as possible, so as to improve the system wavelength division multiplexing efficiency.

Description of drawings

FIG. 1 is a three-dimensional schematic diagram of a tunnel according to the present invention.

Figure 2 is a schematic diagram of the tunnel monitoring section.

Figure 3 is a schematic diagram of the structure of the temporary protection wooden box.

Figure 4 is a schematic cross-sectional view of the tunnel in the unfolded state of the formwork trolley.

Figure 5 is a schematic diagram of the wavelength distribution of fiber grating sensors in series, in the figure: ①: strain wavelength region; ②: buffer zone; ③: temperature wavelength zone; ④: buffer zone.

List of reference numbers:

1-tunnel, 2-temporary optical cable, 3-monitoring section, 4-temporary protection wooden box, 401-opening, 402-slope, 403-cover plate, 5-fiber grating monitoring instrument, 6-pigtail cable, 7-template table cart, 8-formwork trolley support, 9-concrete lining, 10-portable fiber grating demodulator, 11-long channel.

Detailed ways

The technical solutions provided by the present invention will be described in detail below with reference to specific embodiments. It should be understood that the following specific embodiments are only used to illustrate the present invention and not to limit the scope of the present invention.

The method for burying and installing a safety monitoring instrument in a long tunnel with high water head provided by the present invention includes the following steps:

Step 1: After the excavation and clearing of the foundation are completed, start to bind the steel bars for pouring the tunnel 1. Before the binding of the steel bars is completed, the formwork trolley tracks are installed in this warehouse synchronously, and the formwork trolley 7 is assembled at the concrete position of the adjacent warehouse. On the tunnel monitoring section 3, a plurality of fiber grating monitoring instruments 5 are bundled along the circumferential direction on the steel bars. The tail cables 6 connected by these instruments are covered with PE pipes (other materials with certain strength can also be used to replace PE) as protection, and the PE pipes are bound with plastic. The belt is bound instead of lead wire, to avoid the lead wire from cutting off the protection tube and the pigtail cable of the instrument when the concrete is vibrated, so as to ensure that the pigtail cable is not damaged. The tunnel monitoring section 3 is mostly fan-shaped, the bottom of the tunnel is a platform, and a long canal 11 is arranged in the middle of the platform that runs through the entire tunnel. The long canal is used to set the main transmission optical cable. A temporary protective wooden box 4 is bundled on the reinforcement bars at the bottom of the tunnel. The cross-section of the temporary protection wooden box is trapezoidal, the top width is 30cm, the bottom width is 40cm, the height is 25cm, and the length is 100cm. The top of the temporary protection wooden box is provided with an openable cover plate 403, and the bottom is provided with an opening 401, and the size of the opening is 20×30 cm. The tail cables 6 connected by the above-mentioned multiple fiber grating monitoring instruments 5 are drawn along the section fan-shaped steel bars and then pulled to the bottom of the section (as shown in FIG. 2 ), and are introduced into the temporary protective wooden box from the opening. The temporary protective wooden box is made of wood, which can be easily removed and taken out after the tunnel section is poured. The height of the top surface of the fixed temporary protection wooden box should be equal to or slightly less than the top surface height of the concrete platform to be formed at the bottom of the tunnel, so as to facilitate the excavation of the temporary protection wooden box. It should be noted that the tunnel monitoring section referred to in the present invention has a certain length along the tunnel axis, usually 1 to 2 m.

The series-connected FBG sensor array contains multiple sensing gratings, and the demodulator "addresses" each grating by the wavelength of the reflected light. Therefore, the wavelengths of the series-connected gratings should be unique, that is, the wavelengths of the sensors should avoid overlapping in the entire range. At the same time, it is required that the wavelength measurement values of the fiber grating instruments in the same group in the same monitoring section are not repeated, and the efficiency of the system wavelength division multiplexing is improved. There are generally two gratings (one for strain and one for temperature grating) in the fiber grating strain gauge or steel bar gauge, and the wavelength of the strain and temperature grating within the range of the sensor is between 1 and 3 nm. Of course, only one grating or a larger number of gratings can be set as required. To improve the reliability of the demodulator based on wavelength addressing, it is recommended to set a buffer zone of 0.5 nm between every two gratings to avoid overlapping wavelengths when adjacent gratings change within the sensor range. The wavelength distribution is generally shown in Figure 5.

Step 2: After the monitoring instrument tail cable enters the temporary protective wooden box, open the cover 403. These monitoring instruments should be divided into several groups. The tail cables of the monitoring instruments in the same group are connected in series with flanges one by one to connect each monitoring instrument in series. Generally, the number of series connections is less than For 5 sensors or 10 wavelengths, the wavelength measurements of the fiber grating instruments in the same group are not repeated. The tail cables of the monitoring instruments connected in series in each group are led out of the wooden box from the gaps of the wooden box or the openings of the wooden box, and the cover is covered and fixed to temporarily protect the gaps and openings of the wooden box, the openings and the tail cables. The voids are sealed with expanding foam to avoid the entry of concrete mortar.

Step 3: Connect the temporary optical cable 2 to the tail cable after the grouping and concatenation of the fiber grating monitoring instruments, lead the temporary optical cable out of the concrete of the warehouse, and connect the temporary optical cable to the portable fiber grating demodulator 10, as shown in Figure 1. , so that data collection can be carried out normally during the construction of concrete lining. Using a portable fiber grating demodulator can test whether the wavelengths of all connected monitoring instruments can be collected normally. If the wavelengths overlap, adjust the serial connection mode until the normal measurement.

After the above steps, the buried installation structure of the safety monitoring instrument in the long tunnel with high water head has been installed. As shown in Figures 1 and 2, the structure includes a number of tunnel monitoring section buried installation units, each section buried installation unit includes a temporary protection wooden box 4 and a plurality of fiber grating monitoring instruments 5 buried on the circumference of the same tunnel monitoring section, Each fiber grating monitoring instrument 5 is connected with a cable, and each fiber grating monitoring instrument 5 is connected in series or in parallel with each other. As shown in FIG. 3 , the temporary protection wooden box 4 is trapezoidal, with an openable cover plate 403 on the top, one side of which has a slope 402 adapted to the side surface 11 of the long canal in the tunnel, and an opening 401 (the opening is It is better to set it at the bottom, but the specific position of the opening can also be changed as needed), the cables connected by each fiber grating monitoring instrument are introduced into the temporary protective wooden box through this opening, and the cables connected by each fiber grating monitoring instrument The cable is used to connect the temporary fiber optic cable or the main transmission fiber optic cable.

Step 4: The formwork trolley is moved into the concrete pouring site along the track in the axial direction of the tunnel. After each work is completed, the formwork trolley is unfolded to form a complete fan shape as shown in Figure 4. Concrete is poured after other special-shaped parts are closed with wooden formwork. When pouring concrete after the formwork trolley enters the warehouse surface, the fiber grating demodulator should be used for measurement according to the required data collection frequency. After the pouring is completed, the temporary protective wooden box in the section buried installation unit and the fiber grating monitoring instrument are buried in the concrete.

The above steps of pouring concrete are as follows:

Concrete is delivered from the movable window of the formwork trolley by means of steel pipe pumping. Concrete is poured into the silo by horizontal layering and symmetrical pumping. The concrete formwork trolley is vibrated by an attached vibrator, which is assisted by an inserted vibrator around the feed window. The concrete pumping hose injects concrete from the feeding window of the formwork trolley (moving up gradually from the bottom window). The thin layer in the warehouse is laid flat, the side walls on both sides are symmetrically cut, and the height of one continuous pouring on one side is not more than 1m to prevent the overall deformation of the formwork.

Preferably, the concrete vibrator adopts a combination of artificial vibrators and plate vibrators. Manual vibrators are used below the second floor window at the bottom, and 8 evenly arranged plate vibrators are used for vibrating the above parts. This way the concrete is poured more evenly.

Step 5, generally 2-3 days after the concrete is poured, the initial setting of the concrete is completed, the formwork trolley is removed, the pre-embedded protective wooden box is dug out, and the tail cable of the instrument is exposed, which can be directly in the inverted arch of the monitoring section. Collect data one by one.

Step 6. After the construction of the concrete lining 9 is completed, the fiber grating monitoring instrument needs to be spliced to the main optical cable in series or in parallel. At this time, the temporary protection wooden box can be removed and taken out, and the optical cable fusion protection box can be installed in the temporary protection wooden box. In the space left in the original temporary protection wooden box, the cables in the original temporary protection wooden box are placed in the optical cable fusion protection box, and the cables are connected in series or parallel according to the needs. After the debugging is completed, all the cables are backfilled with concrete.

The technical means disclosed in the solution of the present invention are not limited to the technical means disclosed in the above embodiments, but also include technical solutions composed of any combination of the above technical features. It should be pointed out that for those skilled in the art, without departing from the principle of the present invention, several improvements and modifications can be made, and these improvements and modifications are also regarded as the protection scope of the present invention.

Claims (10)

1. the Embedment and installation method of Safety Monitoring Instruments in the long tunnel of high water head, which comprises the steps of:

Step 1 after the completion of excavating clear base, starts assembling reinforcement, and installation template platform is synchronized in this storehouse before reinforcing bar binding is completed Track road, while formwork jumbo is assembled in adjacent storehouse concrete position and is completed, it is circumferentially square on same tunnel monitoring section reinforcing bar To multiple FBG monitoring instruments are installed, the readily removable interim protection wooden case removed is fixed on tunnel floor reinforcing bar, it is the multiple The stern fast that FBG monitoring instrument picks out introduces in interim protection wooden case from interim protection wooden case opening；

The grouping of these stern fasts is together in series after monitoring instrument stern fast enters interim protection wooden case, temporarily protects wooden case by step 2 Gap between opening and cable is sealed using expanded foam, and concrete mortar is avoided to enter；

Step 3, grouping will connect with the temporary cable for guiding to lower storehouse concrete after each FBG monitoring instrument concatenation, use Portable fiber-optic grating demodulation instrument tests whether whole monitoring instrument wavelength of energy normal acquisition connection, if any overlapping wavelengths, then Tandem is adjusted, until normal measurement；

Step 4, formwork jumbo move into concreting position, after work in every is complete, template along the track of tunnel axial direction Trolley expansion closes after-pouring concrete in other special-shaped parts wooden model, enters storehouse surface after-pouring concrete in formwork jumbo When, data acquisition frequency measurement as required；

Step 5 removes formwork jumbo, pre-buried interim protection wooden case is dug out, instrument is connected after concrete completes initial set It draws stern fast and directly acquires data one by one at the inverted arch position of monitoring section；

Step 6 after the completion of lining construction, is removed interim protection wooden case and is simultaneously drawn off, optical cable welding protecting box is mounted on and is faced When the space that is left in lining cutting of protection wooden case, main cable will be fused to after FBG monitoring instrument serial or parallel connection, debugged It is last after the completion all to use concrete backfill.

2. the Embedment and installation method of Safety Monitoring Instruments in the long tunnel of high water head according to claim 1, it is characterised in that: The wavelength measured value of fiber grating instrument in same group of the same monitoring section does not repeat.

3. the Embedment and installation method of Safety Monitoring Instruments, feature exist in the long tunnel of high water head according to claim 1 or 2 In: at least one grating is set in FBG monitoring instrument, when 2 and the above grating is arranged, sets buffer area between every 2 gratings 0.5nm。

4. the Embedment and installation method of Safety Monitoring Instruments in the long tunnel of high water head according to claim 1, it is characterised in that: Serial number is less than 5 sensors or 10 wavelength in the step 2.

5. the Embedment and installation structure of Safety Monitoring Instruments in the long tunnel of high water head, it is characterised in that: disconnected including the monitoring of several tunnels Face Embedment and installation unit, the tunnel monitoring section Embedment and installation unit include interim protection wooden case and it is several be embedded in it is same FBG monitoring instrument on tunnel monitoring section circumference, each FBG monitoring instrument are respectively connected with stern fast, each optical fiber light Grid monitoring instrument is one another in series or in parallel, the interim protection wooden case be it is trapezoidal, top has openable cover board, side tool There is the inclined-plane being adapted with the side Chang Qu in tunnel, is provided with opening, the cable that each FBG monitoring instrument picks out on cabinet It is introduced in interim protection wooden case by the opening, the cable is for connecting temporary cable or main transmission cable.

6. the Embedment and installation structure of Safety Monitoring Instruments in the long tunnel of high water head according to claim 5, it is characterised in that: Protection pipe is arranged with outside the cable.

7. the Embedment and installation structure of Safety Monitoring Instruments in the long tunnel of high water head according to claim 6, it is characterised in that: The protection pipe is PE pipe.

8. the Embedment and installation structure of Safety Monitoring Instruments in the long tunnel of high water head according to claim 5, it is characterised in that: The interim protection wooden case is embedded in tunnel floor platform, and apical side height is less than or equal to platform apical side height.

9. the Embedment and installation structure of Safety Monitoring Instruments in the long tunnel of high water head according to claim 5, it is characterised in that: The opening setting is on temporarily protection wooden case bottom surface.

10. the Embedment and installation structure of Safety Monitoring Instruments, feature exist in the long tunnel of high water head according to claim 5 In: each FBG monitoring instrument is connected by flange for carrying out construction time sight in same tunnel section Embedment and installation unit It surveys.