CN206772242U - A kind of tunnel wall rock deformation distributed optical fiber sensing device based on pipe shed support - Google Patents

Abstract

The utility model discloses a distributed optical fiber monitoring device for tunnel surrounding rock deformation based on pipe shed support. A single segment of a fiber measuring tube is composed of an optical fiber, an extension conversion joint and a hollow circular tube. There are orthogonal and symmetrical grooves, the optical fiber is pasted on the surface of the groove, and the end is provided with an extension conversion joint; the steel pipe of the pipe shed is hollow and the side wall is provided with a slurry outlet, and the guide pipe is inserted obliquely on the steel arch. A steel arch frame is installed on the top, the steel pipe of the pipe shed is located in the guide pipe, the single section of the fiber optic measuring tube is located in the steel pipe of the pipe shed, the drill bit of the drilling rig passes through the guide pipe, the drill pipe of the drilling rig is located in the steel pipe of the pipe shed, and the single section of the optical fiber measuring pipe is placed in the steel pipe of the pipe shed. One end of the section has an optical fiber lead-out pipe, and a grouting hole is opened on the optical fiber lead-out pipe, and the sensing optical fiber of the single-segment optical fiber measuring tube of the monitoring hole is connected in series through an extension conversion joint. The structure is simple and easy to use. A single segment of the optical fiber measuring tube is placed in the steel tube of the tube shed, which greatly increases the safety of tunnel construction.

Description

A distributed optical fiber monitoring device for tunnel surrounding rock deformation based on pipe shed support

technical field

The utility model belongs to the technical field of tunnel advance support monitoring, and more specifically relates to a distributed optical fiber monitoring device for tunnel surrounding rock deformation based on pipe shed support.

Background technique

In the process of tunnel excavation, it is often encountered in areas such as broken zones, loose zones, weak ground, water gushing, sand gushing, etc. If excavation is carried out under such geological conditions, if no advance pre-support is carried out, collapses are likely to occur. Leading to safety accidents will not only cause economic losses to related enterprises, increase project costs, but also greatly affect project construction progress and construction quality. Before the excavation of existing lines or buildings and rivers and lakes under the tunnel construction, if no advanced pre-support is carried out, it is easy to cause the settlement of the existing lines or buildings on the tunnel and the water gushing of rivers and lakes to bring various Security risks.

The advance support of the pipe shed is to drive a group of steel pipes (i.e. pipe shed pipes) into the ground along the outside of the excavation contour of the tunnel, and combine them with the steel arch to form a powerful pre-support reinforcement system for the shed. , to support the load from the upper surrounding rock of the pipe shed, and pressurize the grout into the formation through the grouting hole to strengthen the weak and broken formation and improve the self-stabilization ability of the formation. While stabilizing the excavation of the surrounding rock, the pipe-shelf support also produces corresponding deformation. By testing the deformation and combining the monitoring results of surface settlement, vault sinking and headroom convergence, a complete pipe-shelf support can be formed The surrounding rock stability evaluation system monitors the deformation of the surrounding rock supported by the pipe shed in real time, which greatly increases the safety of tunnel construction.

At present, in the field of tunnel advance support monitoring technology, especially the technical methods related to the monitoring of tunnel engineering during the construction period, there are mainly soil settlement monitoring technology in the ground, soil inclination measurement technology, surface and vault settlement monitoring technology, etc. There are many instruments and equipment Using subsidence instrument, inclinometer, total station, level and so on. These technical methods have the characteristics of point measurement, and the measurement points are sparse, so it is difficult to realize all-round monitoring of the measured object. Most of the conventional monitoring technologies still cannot realize real-time monitoring, and there are various sensing principles and data types, making it difficult to integrate a large-scale real-time monitoring system. Therefore, it is necessary to research and develop methods and technologies suitable for the advance real-time monitoring of surrounding rock deformation in tunnel pipe shed advance support tunnels, so as to meet the growing requirements of tunnel construction safety monitoring and theoretical research needs.

Pre-pulse-pumped Birlouin Optical Time-Domain Analysis (PPP-BOTDA) based on the principle of Brillouin scattering is a very promising strain and temperature monitoring technology. In addition to the corrosion resistance and anti-interference characteristics of general optical fiber sensing technology, this technology is also an upgraded product of the traditional BOTDA system, which realizes high-resolution (<10cm) and high-precision (<±8) measurement. and accuracy have obvious advantages. Before introducing the pulsed light, the technology loads the appropriate pulsed pre-pumped light to pre-excite the phonons, and then uses the stimulated Brillouin scattering effect of the pulsed light in the fiber and optical time domain reflection technology to realize the long-distance measurement of temperature and strain. Fully distributed measurement can obtain strain and temperature information at any point along the optical fiber. PPP-BOTDA distributed optical fiber is suitable for the detection and monitoring of the health status of large structures. At present, there is no relatively complete distributed optical fiber monitoring technology in the monitoring of tunnel surrounding rock advance support. It is especially suitable for special difficult areas, such as extremely broken rock mass, fault broken rock mass, landslide mass, rock cone section, sandy soil stratum, strong expansive stratum, strong rheological stratum, fractured rock mass, shallow buried large deviation Deformation monitoring of tunnel advance support in pressure equal surrounding rock.

Contents of the invention

The purpose of this utility model is to provide a distributed optical fiber monitoring device for tunnel surrounding rock deformation based on pipe shed support, which is simple in structure and easy to use. A single segment placed in the steel pipe shed can form a complete evaluation system for the stability of the surrounding rock supported by the pipe shed, and monitor the deformation of the surrounding rock supported by the pipe shed in real time, greatly increasing the safety of tunnel construction.

In order to achieve the above-mentioned purpose, the utility model adopts the following technical measures:

Its technical idea is: drive the steel pipe shed along the outer side of the excavation contour line of the tunnel into the ground for monitoring, and connect the steel pipes with screws; The single segment of the prefabricated segmented optical fiber measuring tube is spliced and assembled. Due to the narrow operating space in the tunnel, the single segment of the optical fiber measuring tube in the previous segment is sent into the steel pipe, and then spliced and assembled at the mouth of the steel pipe. The segmented optical fiber measuring tube is a single segment, and the splicing and assembling methods of the single segment of the optical fiber measuring tube of multiple segments are the same.

A distributed optical fiber monitoring method for tunnel surrounding rock deformation based on pipe shed support, the steps of which are:

Step 1. Use the pipe shed drilling rig to drill holes from the guide pipe and follow up the casing, drill monitoring holes along the set position outside the tunnel excavation contour line, and lay steel pipes horizontally; the pipe shed steel pipes are jacked in mechanically. The steel pipe segments are connected with screws;

Step 2. After the top of the steel pipe in the pipe shed is in place, connect the first groove and the second groove fiber conversion extension connector in series at the beginning end of the first segment of the fiber optic measuring tube, and the third groove and the fourth groove. Convert and extend the joints in series and overlap, seal and protect the optical fiber joints with plastic film, and slowly push in mechanically, and send the beginning end of the single segment of the optical fiber measuring tube into the steel pipe of the pipe shed, and reserve 0.18-0.22m at the steel pipe mouth The length of the single segment of the optical fiber measuring tube, pay attention to ensure that the first groove of the single segment of the optical fiber measuring tube is vertically upward;

Step 3: Splice the single segment of the fiber optic tube of the second segment at the mouth of the steel pipe with the end of the single segment of the fiber tube of the first segment by using an inner tube cementation method. When splicing, ensure that the single segment of the two fiber tubes is spliced The grooves are aligned, and the optical fibers are connected in series to form vertical and horizontal optical fiber loops with extended conversion joints. The optical fiber joints are sealed and protected with plastic films. Enter the steel pipe in the pipe shed, and reserve a length of 0.18-0.22m for a single segment of the fiber optic tube at the steel pipe mouth, and ensure that the first groove of the single segment of the fiber tube tube is vertically upward;

Step 4. The single-segment splicing method of the optical fiber measuring tube of other segments is the same as the single-segment splicing method of the second segment of optical fiber and the third segment of optical fiber measuring tube described in step 3, and finally the length of the steel pipe with the same length as that of the pipe shed can be obtained. Fiber optic tube single segment;

Step 5. Install the drilling and sealing device, use the grouting machine to inject the configured cement slurry until the slurry fills the gap between the single segment of the optical fiber measuring tube and the surrounding rock of the tube shed, and use the protective sleeve to pass the optical fiber through the cover of the drilling and sealing device The optical fiber lead-out hole on the lead out of the pipe shed steel pipe.

Step 6. Connect the sensing optical fiber of the single segment of the optical fiber measuring tube at different monitoring positions of the tunnel pipe shed support structure in series through the extension conversion joint, and use the PPP-BOTDA pre-pulse pumped Brillouin optical time domain analyzer to measure the optical fiber synchronously. The strain distribution constitutes a distributed optical fiber monitoring network. The two-dimensional displacement distribution of a single segment of the optical fiber measuring tube is calculated through strain difference and integral calculation, and the deformation of the surrounding rock supported by the tunnel pipe shed is monitored in advance in real time.

Through the above monitoring method, the deficiencies of the conventional monitoring methods and means of tunnel advance support are improved, and the distributed monitoring and advance monitoring of the surrounding rock of tunnel pipe shed support are realized, which overcomes the shortcomings of discontinuous measurement points of traditional monitoring methods, and high-density measurement points The spacing can reach 5cm, and it has the characteristics of economy, convenience, anti-interference and excellent durability.

A distributed optical fiber monitoring device for tunnel surrounding rock deformation based on pipe shed support. The groove, the fourth groove, the extension conversion joint, the guide pipe, the monitoring hole, the pipe shed steel pipe, the grout hole, the guide wall, the steel arch frame, the grout hole, the optical fiber lead-out pipe, and the drilling rig. The connection relationship is: optical fiber measurement The single section of tube is composed of optical fiber, extension conversion joint and hollow circular tube. The outer wall of single section of fiber optic tube is provided with the first groove, the second groove, the third groove and the fourth groove which are orthogonal and symmetrical. The optical fiber is pasted on the surface of the groove, and the end is equipped with an extension conversion joint for splicing; the steel pipe of the pipe shed is hollow and has multiple (60-120) on the side wall (the diameter of the slurry hole is 12mm, the hole spacing is 15cm, and it is arranged in a plum blossom shape) The slurry hole; the guide pipe and the guide wall play a guiding role for the drilling rig, and the guide pipe is obliquely inserted on the steel arch frame; the steel arch frame is installed on the guide wall, and the steel pipe of the pipe shed is located in the guide pipe. Advance towards the face of the tunnel, the single segment of the fiber optic measuring tube is located in the steel pipe of the pipe shed, the drill bit of the drilling rig passes through the guide pipe, the drill pipe of the drilling rig is located in the steel pipe of the pipe shed, and an optical fiber is led out at one end of the single segment of the fiber optic measuring tube The pipe has a grouting hole on the optical fiber lead-out pipe, through the grouting hole, the single segment of the optical fiber measuring tube and the steel pipe of the pipe shed are deformed under the action of the surrounding rock, and the optical fiber is drawn out from the optical fiber lead-out pipe to facilitate monitoring; different monitoring holes The single-segment sensing fiber of the optical fiber measuring tube is connected in series through an extension conversion joint, and the strain distribution of the fiber is measured synchronously by the PPP-BOTDA pre-pulse pumped Brillouin optical time domain analyzer.

The single segment of the optical fiber measuring tube includes a tight-skinned optical fiber, a conversion extension joint and a hollow circular tube. The tight-skinned optical fiber is glued to the groove surface of the outer wall of the hollow circular tube with epoxy resin, and is connected with the conversion extension at the end of the circular tube. The joints are connected in series; the outer wall of the hollow tube used is provided with a first groove, a second groove, a third groove and a fourth groove; the first groove, the second groove, the third groove The included angles between the groove and the fourth groove are 180 degrees, 90 degrees (counterclockwise direction) and 90 degrees (clockwise direction); the first groove and the second groove of the single segment of the optical fiber measuring tube The 1st, 3rd and 4th grooves are respectively pasted and arranged with predetermined lengths of tight-skinned optical fibers, and the ends of the optical fibers are provided with conversion extension connectors.

As a preference, the hollow round pipe used in the present invention is a PP-R pipe, which has good flexibility. The diameter of the hollow round pipe can be determined according to the inner diameter of the steel pipe used for pipe shed support, and is smaller than the inner diameter of the steel pipe.

As preferably, the length of the single hollow tube used in the utility model is generally 2 or 4m, the outer diameter of the hollow tube is not less than 40mm, the wall thickness of the hollow tube is not less than 5mm, and the hollow tube is not less than 5mm. The cross-sectional dimensions of the first groove, the second groove, the third groove and the fourth groove opened on the outer wall are all 3mm×3mm, and the ends of the two hollow round pipes can be cemented through the inner joint. Pay attention when connecting Groove alignment.

As a preference, the distributed optical fiber adopted in the utility model is a strain sensing optical fiber with a tight sheath, and the length of the optical fiber is slightly greater than the length of a single hollow tube, generally 2.2 or 4.2m, and each of the two ends of the hollow tube is 0.1 m longer. The length of the optical fiber is reserved, and both ends of the optical fiber are equipped with conversion extension connectors; the optical fibers corresponding to the first groove, the second groove, the third groove and the fourth groove of the hollow circular tube are connected in series with conversion extension connectors, and the The outer core of the distributed optical fiber is packaged with a protective layer of polyurethane elastic material, the diameter of the distributed optical fiber is 2 mm, and the weight is 2 kg/km.

Through the above-mentioned device, the shortcomings of inconvenient layout, difficult operation and heavy monitoring workload of traditional monitoring devices are overcome. A single optical fiber is used as both a sensing element and a signal transmission channel without additional wires, which is beneficial to data acquisition, transmission and construction. The optical fibers of monitoring holes at different positions can be connected in series, which makes data collection and extraction relatively simple and easy during large-scale deployment. It can be used for many monitoring projects, and the cost of large-scale monitoring is low, and the monitoring efficiency is improved;

A method for preparing (prefabricating) a single segment of an optical fiber measuring tube, the steps of which are:

A. Determine the length and quantity of the hollow circular pipe according to the length of the steel pipe supported by the tunnel pipe shed, and carry out groove processing on the hollow circular pipe, that is, the first groove, the second groove, and the third groove on the outer wall of the hollow circular pipe The cross-sectional dimensions of the groove and the fourth groove are both 3mm×3mm, and the included angles between the first groove, the second groove, the third groove and the fourth groove are respectively 180 degrees and 90 degrees (counterclockwise direction) and 90 degrees (clockwise);

B. After the slotting is completed, wash the adhesive surface of the groove with absolute ethanol and air dry to ensure that the adhesive surface is clean to ensure the quality of the adhesive;

C. Strictly adjust the epoxy resin in proportion, first spread the epoxy resin with a thickness of 0.4-0.6mm along the first groove at one end of the hollow tube, and lay the conversion extension joints at both ends along the first groove in time The tight-skinned optical fiber reaches the end of the groove of the hollow tube. Note that 0.1m of optical fiber is reserved at each end. During this process, ensure that the optical fiber is properly tightened and kept straight, and the initial bending defect of the optical fiber must not be artificially caused; after 30-40 minutes The underlying epoxy resin reaches the initial setting strength, readjust the epoxy resin, and scrape the covering epoxy resin until it reaches the designed coating thickness, so that the epoxy resin layer is basically consistent with the outer wall of the hollow tube;

D. The bonding method of the optical fiber in the second groove, the third groove and the fourth groove is the same as that of the first groove, and the specific operation repeats step C once;

According to classical mechanics of materials, among the various methods for calculating structural deformation, the strain quadratic integral method can directly establish the relationship between structural strain and deformation, and the calculation is as follows

In the formula: w(x) is the vertical deformation at the coordinate x of the structure axis, which is positive downward; ε(x) is the strain at the distance y away from the neutral axis at the lower part of the structure, and is positive under tension; A and B are respectively x = The rotation angle and deformation at 0, the rotation angle is positive in the counterclockwise direction.

The pipe shed steel pipes are arranged along the excavation contour line of the tunnel to the face of the tunnel according to a certain length of 10-45m. The axis of the steel pipes and the tunnel axis have a certain angle α=1-13°. The single-segment single-segment outlet end first undergoes settlement deformation, and the other end is relatively fixed in the forward direction (no rotation angle or displacement), which can be simplified as a cantilever beam model, with the axis of the steel pipe of the pipe shed as the coordinate axis x-axis, with Enter the boundary of the cantilever beam model x=0, w(0)=0; x=0, θ(0)=0 to the formula (1), get A=0, B=0, then the single segment of the fiber optic tube The displacement at any position x of the segment (Fig. 1) relative to the base point 0 is:

Projected to the coordinate system with the axis of the tunnel as the horizontal axis, the horizontal displacement distribution of a single segment of the fiber optic tube is given by formula (2). The vertical displacement distribution of a single segment is:

In the formula: Δε(x) is the difference between the first groove and the second groove or the third groove and the fourth groove of the hollow tube symmetrically arranged in the optical fiber strain change value (relative to the initial strain change value), D is the outer diameter of the hollow circular tube, α is the angle between the axis of the steel pipe and the axis of the tunnel, cosα is the cosine value of the angle between the axis of the steel pipe and the axis of the tunnel, W ₁ (x) is the vertical displacement distribution of a single segment of the optical fiber measuring tube; According to the formula (3), the vertical displacement distribution of the single segment of the optical fiber measuring tube can be calculated by performing difference and integral operations on the strains of the first and second grooves of the hollow tube; According to the formula (2), the displacement in the horizontal direction of the single segment of the optical fiber measuring tube can also be calculated by performing difference and integral operations on the strains of the two optical fibers on the left and right sides of the third groove and the fourth groove of the hollow tube distributed.

When the support structure of the tunnel tube shed deforms, the hollow circular tube will deform synchronously with the tube shed, and the four sensing optical fibers arranged in the hollow circular tube will generate corresponding strains with the deformation of the tube, and the first groove of the hollow circular tube will and the strain of the two optical fibers above and below the second groove, the difference and integral calculation can be used to calculate the vertical displacement distribution of the single segment of the optical fiber measuring tube. Similarly, the third groove and the fourth groove of the hollow tube The strain of the two optical fibers on the left and right of the groove can be calculated by performing difference and integral calculations to calculate the horizontal displacement distribution of a single segment of the optical fiber measuring tube. The subtraction operation refers to the subtraction of the strain values of the optical fibers distributed symmetrically between the first groove and the second groove or the third groove and the fourth groove of the hollow tube to obtain the vertical and horizontal two-dimensional values of the sensor respectively. Differential strain distribution; the displacement of any point of the hollow circular tube relative to the base point 0 is obtained by performing a quadratic integral operation on the differential strain distribution along the length of the hollow circular tube; Segmented and single-segment sensing fibers are connected in series through extended conversion joints, and the PPP-BOTDA pre-pulse pumped Brillouin optical time domain analyzer measures the strain distribution of the optical fibers synchronously, forming a distributed optical fiber monitoring network, and monitoring the tunnel tube in real time ahead of time The deformation of the surrounding rock supported by the shed.

Compared with the existing monitoring technology, the utility model has the biggest feature of providing a distributed optical fiber monitoring method and device for tunnel surrounding rock deformation based on pipe shed support. The advantages are as follows:

1) By placing the prefabricated optical fiber measuring tube into the steel pipe of the tunnel pipe shed, the dynamics of the surrounding rock supported by the pipe shed during the tunnel excavation are monitored to achieve advanced and real-time monitoring;

2) Distributed monitoring can be realized, and the distance between high-density measuring points can reach 5cm, which overcomes the shortcomings of discontinuous measuring points in traditional monitoring methods in tunnels.

3) A single optical fiber is used as both a sensing element and a signal transmission channel. It does not require additional wires, which is beneficial to data acquisition, transmission and construction. It has many advantages such as economy, convenience, anti-interference, excellent durability, and stable and reliable data;

4) Sensors can be connected in series to make data collection and extraction easier when deployed on a large scale, and can be used for many monitoring items, with low cost for large-scale monitoring and improved monitoring efficiency;

5) Based on the monitoring results of surface settlement, vault sinking and headroom convergence, a complete evaluation system for the stability of the surrounding rock supported by the pipe shed can be formed, and the deformation of the surrounding rock supported by the pipe shed can be monitored in real time, greatly increasing the tunnel construction. security;

Description of drawings

Figure 1 is a simplified schematic diagram of a monitoring principle model based on pipe shed support.

Fig. 2 is a schematic diagram of a single-segment structure of an optical fiber measuring tube.

Fig. 3 is a schematic cross-sectional view of a single segment of an optical fiber measuring tube.

Fig. 4 is a schematic diagram of the layout position of drilling holes for tunnel pipe shed support.

Fig. 5 is a structural schematic diagram of a pipe shed steel pipe.

Fig. 6 is a schematic cross-sectional view of a pipe-shelf composite pipe.

Fig. 7 is a schematic structural diagram of a distributed optical fiber monitoring device for tunnel surrounding rock deformation based on pipe shed support.

In the figure, 1-single segment of fiber optic measuring tube, 1-1-optical fiber, 1-2-hollow circular tube, 1-3-inner tube, 1-4-first groove, 1-5-second groove , 1-6-the third groove, 1-7-the fourth groove, 1-8-extended adapter, 2-guide pipe, 3-monitoring hole, 4-pipe shed steel pipe, 5-slurry hole, 6 - Guide wall, 7 - Steel arch frame, 8 - Grouting hole, 9 - Optical fiber outlet pipe, 10 - Drilling rig (ZSDL-160 multifunctional full hydraulic crawler drilling rig).

detailed description

Example 1:

According to Fig. 1, Fig. 2, Fig. 3, Fig. 4, Fig. 5, Fig. 6, and Fig. 7, it can be seen that a distributed optical fiber monitoring method for tunnel surrounding rock deformation based on pipe shed support, specifically includes the following steps:

Step 1. Use the pipe shed drilling rig 10 to drill holes from the guide pipe 2 and the steel pipe 4 to follow up. Drill the monitoring hole 3 and lay the steel pipe 4 horizontally along the set position outside the tunnel excavation outline; the pipe shed steel pipe 4. It is jacked by machinery, and the 4 sections of the steel pipe are connected with screws;

Step 2. After the top of the steel pipe 4 in the pipe shed is in place, the first groove 1-4 and the second groove 1-5 at the beginning of the first segment of the fiber optic tube single segment 1 are overlapped in series with the fiber conversion extension connector 1-8 , the third groove 1-6 and the fourth groove 1-7 optical fiber conversion extension joint 1-8 are connected in series, the optical fiber joint is sealed and protected with a plastic film, and the optical fiber measuring tube is single-segmented by mechanical slow jacking 1. Feed the starting end into the steel pipe 4 of the pipe shed, and reserve 0.2m length of the single segment 1 of the optical fiber measuring tube at the mouth of the steel pipe 4, and pay attention to ensure that the first groove 1-4 of the single segment 1 of the optical fiber measuring tube is vertically upward;

Step 3: Splice the single section 1 of the fiber optic tube of the second section at the mouth 4 of the steel pipe with the inner tube 1-3 cementation method, and splice it with the end of the single section of the single section 1 of the fiber optic tube of the first section. Ensure that the grooves of the single section 1 of the two optical fiber tubes are aligned. The optical fiber 1-1 is connected in series with the extension adapter 1-8 to form a vertical and horizontal optical fiber loop. The optical fiber joint is sealed and protected with a plastic film. Slowly jacking, send the single section 1 of the second section of fiber optic measuring tube into the steel pipe 4 of the pipe shed, and reserve 0.2m length of the single section 1 of the fiber optic measuring tube at the mouth of the steel pipe 4, pay attention to ensure that the fiber optic measuring tube The first groove 1-4 of the pipe single segment 1 is vertically upward;

Step 4. The splicing method of the single segment 1 of the fiber optic tube of other segments is the same as the splicing method of the single segment 1 of the second segment of the fiber tube tube and the single segment 1 of the third segment of the fiber optic tube described in step 3, and finally can be Obtain the single-segment single-segment 1 of the optical fiber measuring tube with the same length as the pipe shed steel pipe 4;

Step 5. Install the drilling and sealing device, inject the configured cement slurry through the grouting hole 8 until the slurry fills the gap between the single segment 1 of the optical fiber measuring tube and the surrounding rock of the pipe shed, and send the optical fiber 1-1 through the drilling and sealing device The optical fiber lead-out pipe 9 on the side leads out the pipe shed steel pipe 4;

Step 6. Connect the sensing optical fiber 1-1 of the single section 1 of the optical fiber measuring tube at the 3 different monitoring holes of the tunnel tube shed support structure in series through the extension conversion joint 1-8, and the Brillouin light is pumped by the PPP-BOTDA pre-pulse The time-domain analyzer simultaneously measures the strain distribution of the optical fiber 1-1 to form a distributed optical fiber monitoring network, calculates the two-dimensional displacement distribution of the single segment 1 of the optical fiber measuring tube through strain difference and integral calculation, and monitors the tunnel shed support in real time in advance Deformation of surrounding rock.

The difference and integral calculations refer to that when the tunnel pipe shed support structure is deformed, the first groove 1-4 and the second groove 1-5 or the third groove 1-6 and the fourth groove of the hollow circular pipe The strain values of the optical fibers 1-1 symmetrically distributed in the grooves 1-7 are subtracted to obtain the two-dimensional differential strain distributions of the single-segment single-segment 1 of the optical fiber measuring tube in the vertical and horizontal directions respectively; by comparing the differential strain distribution Carry out the second integral operation along the length of the hollow circular tube 1-2 to obtain the displacement of any point of the hollow circular tube 1-2 relative to the base point 0, and the single segment 1 The sensing fiber 1-1 is connected in series through the extension conversion joint 1-8, and the strain distribution of the fiber 1-1 is measured synchronously by the PPP-BOTDA pre-pulse pumped Brillouin optical time domain analyzer to form a distributed fiber monitoring network, which is ahead of time. Real-time monitoring of the deformation of the surrounding rock supported by the tunnel pipe shed.

The calculation formula of the integral operation is: under the coordinate system with the axis of the tunnel as the horizontal axis, the horizontal displacement distribution of the single segment of the optical fiber measuring tube is: The vertical displacement distribution of a single segment of the fiber optic tube is In the formula, Δε(x) is the difference between the first groove and the second groove or the third groove and the fourth groove of the hollow tube symmetrically arranged in the optical fiber strain change value (relative to the initial strain change value), and D is The outer diameter of the hollow circular tube, α is the angle between the axis of the steel tube and the axis of the tunnel.

Example 2:

According to Fig. 2, Fig. 3, Fig. 4, Fig. 5, Fig. 6, and Fig. 7, it can be seen that a distributed optical fiber monitoring device for tunnel surrounding rock deformation based on pipe shed support, which consists of a single section of optical fiber measuring pipe 1, an optical fiber 1-1, hollow round tube 1-2, inner connection tube 1-3, first groove 1-4, second groove 1-5, third groove 1-6, fourth groove 1-7, extension Conversion joint 1-8, guide pipe 2, monitoring hole 3, pipe shed steel pipe 4, slurry outlet 5, guide wall 6, steel arch frame 7, grouting hole 8, optical fiber outlet pipe 9, drilling rig 10, and its connection relationship Yes: the single section 1 of the fiber optic tube is composed of an optical fiber 1-1, an extension conversion joint 1-8 and a hollow circular tube 1-2, and the outer wall of the single section 1 of the fiber optic tube has a first orthogonally symmetrical groove 1 -4, the second groove 1-5, the third groove 1-6 and the fourth groove 1-7, the optical fiber 1-1 is pasted on the surface of the groove, and the end is provided with an extension conversion joint 1-8 to facilitate splicing The steel pipe 4 of the pipe shed is hollow and the side wall is provided with a plurality of slurry outlet holes 5; the guide pipe 2 and the guide wall 6 play a role in guiding the direction of the drilling machine 10, and the guide pipe 2 is obliquely inserted on the guide wall 6, and the guide wall 6 is installed There is a steel arch frame 7, the pipe shed steel pipe 4 is located inside the guide pipe 2, the drill bit of the drilling rig 10 passes through the guide pipe 2, the drill pipe of the drilling rig 10 is located inside the pipe shed steel pipe 4, and is continuously pushed toward the face of the drill rig 10 during the drilling process Finished, the single section 1 of the optical fiber measuring tube is located inside the steel pipe 4 of the pipe shed, an optical fiber outlet pipe 9 is opened at one end of the single section 1 of the optical fiber measuring pipe, and a grouting hole 8 is opened on the optical fiber outlet pipe 9. The grout hole 8 is injected to make the single segment 1 of the optical fiber measuring tube and the steel pipe 4 of the pipe shed coordinately deform under the action of the surrounding rock. The sensing fiber 1-1 of 1 is connected in series through the extension conversion joint 1-8, and the strain distribution of the fiber 1-1 is measured synchronously by the PPP-BOTDA pre-pulse pumped Brillouin optical time domain analyzer.

The single segment 1 of the optical fiber measuring tube includes a tight-skinned optical fiber 1-1, a conversion extension joint 1-8 and a hollow round tube 1-2, and the tight-skinned optical fiber 1-1 is glued to the hollow round tube 1-1 by epoxy resin glue. 2 The groove surface of the outer wall is connected in series with the conversion extension joint 1-8 at the end of the round pipe; the outer wall of the hollow round pipe 1-2 adopted is provided with a first groove 1-4 and a second groove 1-5 , the third groove 1-6 and the fourth groove 1-7; the first groove 1-4, the second groove 1-5, the third groove 1-6 and the fourth groove 1-7 The angles between them are 180 degrees, 90 degrees (counterclockwise direction) and 90 degrees (clockwise direction); the first groove 1-4, the second groove 1- 5. The third groove 1-6 and the fourth groove 1-7 are respectively glued and laid with a predetermined length of tight-skinned optical fiber 1-1, and the ends of the optical fiber 1-1 are provided with conversion extension connectors 1-8.

As preferably, the hollow circular pipe 1-2 adopted in the utility model is a PP-R pipe, which has good flexibility. The inner diameter is determined by 76mm or 108mm, and is smaller than the inner diameter of steel pipe 4.

As preferably, the length of the single hollow tube 1-2 used in the utility model is generally 2m or 4m, the wall thickness of the hollow tube 1-2 is 6.9mm or 10.3mm, and the outer wall of the hollow tube 1-2 is The cross-sectional dimensions of the first groove 1-4, the second groove 1-5, the third groove 1-6 and the fourth groove 1-7 are all 3mm×3mm, and the two hollow tubes 1 The end of -2 can be cemented through the inner connecting pipe 1-3, and the groove alignment should be paid attention to when docking.

As a preference, the distributed optical fiber 1-1 used in the present invention is a tight sheathed strain sensing optical fiber, and the length of the optical fiber 1-1 is slightly longer than the single length of the hollow tube 1-2, generally 2.2 or 4.2m. Both ends of the hollow tube 1-2 have an extra 0.1m to reserve the length of the optical fiber 1-1, and both ends of the optical fiber 1-1 are equipped with conversion extension connectors 1-8; the first groove 1-8 of the hollow tube 1-2 4. The optical fibers 1-1 corresponding to the second groove 1-5, the third groove 1-6, and the fourth groove 1-7 are connected in series using a conversion extension connector 1-8, and the fibers of the distributed optical fiber 1-1 A protective layer of polyurethane elastic material is packaged outside the core, and the diameter of the distributed optical fiber 1-1 is 2mm, and the weight is 2kg/km.

Through Embodiment 2, the disadvantages of inconvenient layout, difficult operation, and heavy monitoring workload of traditional monitoring devices are overcome. The single optical fiber 1-1 is used as both a sensing element and a signal transmission channel, without additional wires, and is useful for data collection and transmission. It is beneficial to the construction. The monitoring holes 3 and the optical fibers 1-1 at different positions can be connected in series, which makes data collection and extraction relatively simple and easy during large-scale deployment. It can be used for many monitoring projects, and the cost of large-scale monitoring is low, and the monitoring efficiency is improved.

Example 3:

A method for preparing a single segment of an optical fiber measuring tube, the steps of which are:

A. According to the length 16m of the supporting steel pipe 4 of the tunnel pipe shed, the single length of the hollow circular pipe 1-2 is determined to be 4m and the quantity is 4 pieces, and the hollow circular pipe 1-2 is grooved, that is, the outer wall of the hollow circular pipe 1-2 The cross-sectional dimensions of the first groove, the second groove, the third groove and the fourth groove opened on the top are all 3mm×3mm, the hollow tube 1-2 the first groove 1-4, the second groove 1-5, the angles between the third groove 1-6 and the fourth groove 1-7 are 180 degrees, 90 degrees (counterclockwise direction) and 90 degrees (clockwise direction);

B. After the slotting is completed, clean the hollow circular tube 1-2 with absolute ethanol to clean the first groove 1-4, the second groove 1-5, the third groove 1-6 and the fourth groove 1-7 The paste surface should be air-dried to ensure that the bonding surface is clean to ensure the paste quality;

C. Modulate the epoxy resin in strict proportion. First, apply 0.5mm thick epoxy resin evenly along the first groove 1-4 at one end of the hollow tube 1-2, and lay it along the first groove 1-4 in time. The tight-skinned optical fiber 1-1 with conversion extension connectors 1-8 at both ends reaches the end of the hollow tube 1-2 groove 1-4. Note that 0.1m of optical fiber 1-1 is reserved at each end. This process must be ensured The optical fiber 1-1 is properly tightened and kept straight, and the initial bending defect of the optical fiber must not be artificially caused; after 30 minutes, the underlying epoxy resin reaches the initial setting strength, and the epoxy resin is re-modulated, and the epoxy resin on the covering layer is scratched until the design coating is reached. Thickness, so that the epoxy resin layer is basically consistent with the outer wall surface of the hollow tube 1-2;

D. The bonding method of the second groove 1-5, the third groove 1-6 and the fourth groove 1-7 optical fiber 1-1 is the same as that of the first groove 1-4, and the specific operation repeats step C once;

The embodiments of the utility model have been described in detail above in conjunction with the accompanying drawings, but the utility model is not limited to the described embodiments. For those of ordinary skill in the art, within the scope of the principles and technical ideas of the utility model, various changes, modifications, replacements and deformations are made to these embodiments without departing from the purpose and scope of the technical solution of the utility model, All of them should be included in the scope of claims of the present utility model.

Claims (5)

1. A kind of 1. monitoring device of the tunnel wall rock deformation distribution type fiber-optic based on pipe shed support, it is characterised in that：It is by optical fiber Test tube single segmental（1）, optical fiber（1-1）, hollow circular-tube（1-2）, inner connecting tube（1-3）, the first groove（1-4）, the second groove（1- 5）, the 3rd groove（1-6）, the 4th groove（1-7）, extend crossover sub（1-8）, guide pipe（2）, monitoring holes（3）, pipe boron steel pipe （4）, slurry outlet（5）, be oriented to wall（6）, steel arch-shelf（7）, injected hole（8）, optical fiber introduction pipe（9）, rig（10）Composition, it is special Sign is：Optical fiber test tube single segmental（1）By optical fiber（1-1）, extend crossover sub（1-8）And hollow circular-tube（1-2）Composition, optical fiber Test tube single segmental（1）Lateral wall is provided with ortho-symmetric first groove（1-4）, the second groove（1-5）, the 3rd groove（1-6）With 4th groove（1-7）, optical fiber（1-1）Paste in groove surfaces, end, which is provided with, extends crossover sub（1-8）；Pipe boron steel pipe（4）In Empty and side wall is provided with slurry outlet（5）, guide pipe（2）Oblique cutting is in steel arch-shelf（7）On, it is being oriented to wall（6）It is upper that steel arch-shelf is housed（7）, Pipe boron steel pipe（4）Positioned at guide pipe（2）It is interior, optical fiber test tube single segmental single segmental（1）Positioned at pipe boron steel pipe（4）It is interior, rig（10） Drill bit passes through guide pipe（2）, rig（10）Drilling rod is located at pipe boron steel pipe（4）It is interior, in optical fiber test tube single segmental（1）One end is provided with light Fine introduction pipe（9）, in optical fiber introduction pipe（9）On be provided with injected hole（8）, monitoring holes（3）Optical fiber test tube single segmental（1）'s Sensor fibre（1-1）By extending crossover sub（1-8）Series connection.
2. 2. a kind of monitoring device of tunnel wall rock deformation distribution type fiber-optic based on pipe shed support according to claim 1, It is characterized in that：Described optical fiber test tube single segmental（1）Including tight skin optical fiber（1-1）, conversion extending connector（1-8）And open circles Pipe（1-2）.
3. 3. a kind of monitoring device of tunnel wall rock deformation distribution type fiber-optic based on pipe shed support according to claim 1, It is characterized in that：Described hollow circular-tube（1-2）Outer wall offer the first groove（1-4）, the second groove（1-5）, it is the 3rd recessed Groove（1-6）With the 4th groove（1-7）, described the first groove（1-4）, the second groove（1-5）, the 3rd groove（1-6）With the 4th Groove（1-7）Between angle be respectively 180 degree, 90 degree and 90 degree, described optical fiber test tube single segmental（1）The first groove （1-4）, the second groove（1-5）, the 3rd groove（1-6）With the 4th groove（1-7）The tight skin light for laying predetermined length is pasted respectively It is fine（1-1）, optical fiber end is equipped with conversion extending connector（1-8）.
4. 4. a kind of monitoring device of tunnel wall rock deformation distribution type fiber-optic based on pipe shed support according to claim 1, It is characterized in that：Described hollow circular-tube（1-2）Single length is in 2 or 4m, described hollow circular-tube（1-2）External diameter it is not small In 40mm, hollow circular-tube（1-2）Wall thickness is not less than 5mm, described hollow circular-tube（1-2）The first groove opened up on outer wall（1- 4）, the second groove（1-5）, the 3rd groove（1-6）With the 4th groove（1-7）Cross sectional dimensions be 3mm × 3mm, two are hollow Pipe（1-2）End is cementing by inner connecting tube, groove alignment.
5. 5. a kind of monitoring device of tunnel wall rock deformation distribution type fiber-optic based on pipe shed support according to claim 1, It is characterized in that：Described optical fiber（1-1）Length be more than hollow circular-tube（1-2）Joint length, in 2.2 or 4.2m, open circles Pipe（1-2）Both ends respectively have more 0.1m and reserve optical fiber（1-1）Length, optical fiber（1-1）Both ends are equipped with conversion extending connector（1-8）, Hollow circular-tube（1-2）, the first groove（1-4）, the second groove（1-5）, the 3rd groove（1-6）With the 4th groove（1-7）It is corresponding Optical fiber（1-1）Using conversion extending connector（1-8）Series connection, described optical fiber（1-1）Fibre core on the outside of be packaged with elastic polyurethane Material.