CN105424000A - Tunnel ground surface settlement monitoring device based on distributed optical fiber sensing and monitoring method - Google Patents

Abstract

The invention relates to a tunnel ground surface settlement monitoring device based on distributed optical fiber sensing and a monitoring method. The tunnel ground surface settlement monitoring device based on distributed optical fiber sensing comprises distributed optical fibers, a datum point arranged at the position 3-5 times of the tunnel hole diameter away from the horizontal distance of the tunnel axis and multiple monitoring points which are symmetrically distributed at equal intervals by taking the tunnel axis as an axis; the datum point and the monitoring points are each provided with an installation base, the distributed optical fibers are arranged in the installation bases of the datum point and the monitoring points and communicate the datum point with the monitoring points. The tunnel ground surface settlement monitoring device based on distributed optical fiber sensing and the monitoring method are simple in step, high in operability and lower in cost.

Description

Based on Characters in Tunnel Surface Settlement monitoring device and the monitoring method of distributing optical fiber sensing

Technical field

The invention belongs to Tunnel Engineering Field Monitoring Technique field, relate to a kind of Characters in Tunnel Surface Settlement monitoring device based on distributing optical fiber sensing and monitoring method.

Background technology

The continuous propelling of the constantly perfect and Midwest Great developing strategy built along with national highway net, highway progressively strides forward to area, high and steep mountains, shallow embedding, bias voltage, large cross-section tunnel also get more and more thereupon, and the situation of the unfavorable geologies such as Soft Rock Tunnel, landslide, karst also gets more and more, its stability of surrounding rock in work progress will face great challenge.Meanwhile, China's urban subway tunnel also gets more and more in recent years, its inevitably face pass through surface buildings compact district, with the complex situations such as the crossings on different level of existing underground structure closely connects, it is higher to the requirement of surface settlement control in work progress.Because tunnel excavation will extend to earth's surface place to the stress disturbance of country rock, the stress-strain state of country rock directly will be reflected in ground settlement, is therefore extremely important to the monitoring of ground settlement in constructing tunnel process.

At present, Characters in Tunnel Surface Settlement monitoring is main adopts conventional engineering monitoring means, namely lays reference point and monitoring point on earth's surface, tunnel, utilize precision level and indium steel ruler to measure, then computational analysis draws the settling amount of each monitoring point.In practical engineering application, conventional means is adopted mainly to face following three aspect problems to Characters in Tunnel Surface Settlement monitoring:

1) scope of application has certain limitation.Existing surface subsidence monitoring method mainly contains levelling process, trigonometric leveling, but these two kinds of methods have intervisibility requirement, very easily by the restriction of topographic condition, especially at the mountainous terrain of earth's surface height big rise and fall, it is very big that it measures difficulty, and measuring accuracy is difficult to ensure; And when tunnel surface vegetation is luxuriant, conventional surface subsidence monitoring means almost cannot be carried out the work.

2) observation process is wasted time and energy.Routine monitoring means need people's movements and postures of actors chi, reading, record, and when monitoring point quantity is more, its observation process needs the manpower of at substantial; Especially, when weather is comparatively severe, monitoring difficulty is very big.

3) automatic monitoring and early warning cannot be realized.Existing monitoring means cannot complete lasting, continual surface subsidence monitoring, feedback monitoring data that cannot be dynamic, real-time, therefore cannot realize the monitoring and warning to Characters in Tunnel Surface Settlement, be unfavorable for the whole process analysis of Characters in Tunnel Surface Settlement, very easily omit dangerous situation.Given this, consider from the aspect such as monitoring effect, economic benefit, existing surface subsidence monitoring technology can not adapt to the development that Tunnel Engineering is built.

Summary of the invention

The present invention is directed to Problems existing in existing tunnel surface subsidence monitoring technology, and then provide simple, the workable and lower-cost Characters in Tunnel Surface Settlement monitoring device based on distributing optical fiber sensing of a kind of step and monitoring method.

The object of the invention is to be realized by following technological means:

Based on a Characters in Tunnel Surface Settlement monitoring device for distributing optical fiber sensing, it is characterized in that: the described Characters in Tunnel Surface Settlement monitoring device based on distributing optical fiber sensing comprises distribution type fiber-optic, be arranged on apart from the reference point in tunnel axis horizontal range 3 ~ 5 times of Tunnel footpaths and take tunnel axis as axle symmetrically multiple monitoring points of equidistantly distributing of shape; Described reference point and monitoring point are provided with mounting base, and described distribution type fiber-optic to be arranged in the mounting base of reference point and monitoring point and to be connected with monitoring point by reference point.

As preferably, mounting base of the present invention comprises concrete bed, fixed support, sleeve pipe and hollow circular-tube; Described casing pipe sleeve is contained in hollow circular-tube outside; The tube wall of described sleeve pipe is connected with concrete bed by fixed support; The inwall of described hollow circular-tube offers the first groove, the second groove and the 3rd groove; Angle between described first groove and the second groove and the 3rd groove is 180 ° and 90 ° respectively; A distribution type fiber-optic is laid with in described first groove, the second groove and the 3rd groove.

As preferably, mounting base of the present invention also comprises the epoxide-resin glue be filled in hollow circular-tube and the only plug being arranged on hollow circular-tube both ends.

As preferably, the longitudinal cross-section of concrete bed of the present invention is trapezoidal, the upper bottom side length of described concrete bed is not more than 40cm, the bottom of described concrete bed is failed to grow up in 20cm, the height of described concrete bed is not more than 50cm, and the buried depth of described concrete bed is not less than 1.5m.

As preferably, the length of hollow circular-tube of the present invention is not more than 10cm, the external diameter of described hollow circular-tube is not more than 6cm, the internal diameter of described hollow circular-tube is not more than 5cm, and the cross sectional dimensions of the first groove that described hollow circular-tube inwall is offered, the second groove and the 3rd groove is 3mm × 3mm.

As preferably, distribution type fiber-optic of the present invention is hard-pressed bale sheath straining and sensing optical cable, is packaged with polyurethane elastomeric materials protective seam outside the fibre core of described distribution type fiber-optic, and the diameter of described distribution type fiber-optic is 2mm, and weight is 2kg/km.

Based on a monitoring method for the foregoing Characters in Tunnel Surface Settlement monitoring device based on distributing optical fiber sensing, it is characterized in that: described monitoring method comprises the following steps:

1) at the earth's surface place excavation pit apart from tunnel axis horizontal range 3 ~ 5 Bei Dong footpath, casting concrete base, mounting and fixing bracket, at fixed support upper weld sleeve pipe;

2) hollow circular-tube be fixed on inside pipe casing and make hollow circular-tube and sleeve pipe bond firmly;

3) 3 distribution type fiber-optics are embedded respectively in the first groove, the second groove and the 3rd groove in hollow circular-tube, only plug is installed at hollow circular-tube two ends, inject epoxide-resin glue to hollow circular-tube inside, complete the laying of reference point;

4) according to step 1) ~ step 3) described method lays monitoring point, described monitoring point with tunnel axis be axle symmetrically shape equidistantly distribute;

5) carry out Real-Time Monitoring to Characters in Tunnel Surface Settlement, the specific implementation of described monitoring method is:

When a certain monitoring point with stratum produce sink time, be laid in respectively the first optical fiber in the first groove of hollow circular-tube inwall, the second groove and the 3rd groove, the second optical fiber and the 3rd fiber-optic monitoring to strain value be respectively ε ₁(x), ε ₂(x), ε ₃x (), fibre strain value ε (x) is axial strain ε _a(x) and bending strain ε _b(x) sum, that is:

ε(x)＝ε _a(x)+ε _b(x)(1)

Can obtain according to geometric relationship:

ε _b(x)＝-Rcos(θ)/ρ(x)(2)

Wherein:

X is certain some horizontal range to reference point on optical fiber;

R is the external diameter of hollow circular-tube;

θ is the angle between the line of the first optical fiber and the second optical fiber and horizontal direction;

The radius-of-curvature that ρ (x) is fibre-optical bending;

ε (x) is with ε _a(x) for axle be cosine fluctuation, and the first optical fiber and the second optical fiber symmetrically shape distribute, therefore can obtain:

${\mathrm{\ϵ}}_a\left(x\right)=\frac{{\mathrm{\ϵ}}_1\left(x\right)+{\mathrm{\ϵ}}_2\left(x\right)}{2}---\left(3\right)$

${\mathrm{\ϵ}}_b\left(x\right)=\frac{{\mathrm{\ϵ}}_1\left(x\right)-{\mathrm{\ϵ}}_2\left(x\right)}{2}---\left(4\right)$

The line of the 3rd optical fiber and the first optical fiber and the second optical fiber is perpendicular, then:

${\mathrm{\ϵ}}_3\left(x\right)={\mathrm{\ϵ}}_a\left(x\right)-\frac{Rsin\left(\mathrm{\θ}\right)}{\mathrm{\ρ}\left(x\right)}---\left(5\right)$

According to formula (5) known ε ₁(x), ε ₃x () is mutual remaining relation, then angle theta is:

$\mathrm{\θ}=arctan\frac{2{\mathrm{\ϵ}}_3\left(x\right)-{\mathrm{\ϵ}}_1\left(x\right)-{\mathrm{\ϵ}}_2\left(x\right)}{{\mathrm{\ϵ}}_1\left(x\right)-{\mathrm{\ϵ}}_2\left(x\right)}---\left(6\right)$

The vertical displacement Δ H of the monitoring point that should sink with stratum generation is:

$\mathrm{\Δ}H={\∫}_0^L{\∫}_0^L\frac{1}{\mathrm{\ρ}\left(x\right)}dxdx---\left(7\right)$

Wherein: L be with stratum produce sink monitoring point and reference point between horizontal range;

Formula (2), formula (6) are substituted into the subsidence value that can draw in formula (7) and produce the monitoring point sunk with stratum.

The present invention is compared with existing monitoring technology, and its remarkable advantage is:

The invention provides a kind of Characters in Tunnel Surface Settlement monitoring device based on distributing optical fiber sensing and monitoring method, this monitoring device mainly comprises reference point, distribution type fiber-optic, monitoring point, and wherein reference point mainly comprises concrete bed, fixed support, sleeve pipe, hollow circular-tube, epoxide-resin glue, only plug.Reference point is laid in the position apart from tunnel axis horizontal range 3 ~ 5 Bei Dong footpath; Monitoring point with tunnel axis be axle symmetrically shape equidistantly distribute; Fixed support and concrete bed is provided with below sleeve pipe; Hollow circular-tube is fixed on inside pipe casing; Be provided with 3 grooves inside hollow circular-tube, in each groove, lay 1 distribution type fiber-optic; Hollow circular-tube two ends are provided with only plug; Epoxide-resin glue is injected in hollow circular-tube inside, distribution type fiber-optic and hollow circular-tube is bonded as one.By measuring the strain value of distribution type fiber-optic, can determine that the relative distance between each monitoring point and reference point changes, and then realizing online, dynamic, the Real-Time Monitoring of Characters in Tunnel Surface Settlement.Specifically, the present invention has the following advantages: the automatic monitoring that 1) can realize Characters in Tunnel Surface Settlement, greatly improves monitoring efficiency, saves manpower, and can feed back ground settlement information in real time, dynamically, realizes the early warning to ground settlement; 2) by force, be not subject to working environment and artificial impact, its monitoring accuracy is higher for good operating stability of the present invention, applicability; 3) the invention process step is simple, workable, cost is lower, has good economic results in society and promotional value.

Accompanying drawing explanation

Fig. 1 is Characters in Tunnel Surface Settlement monitoring device structural representation provided by the present invention;

Fig. 2 is reference point structural representation of the present invention;

Fig. 3 is hollow circular-tube of the present invention and distribution type fiber-optic structural representation;

Fig. 4 is calculation of ground surface settlement model schematic of the present invention;

Description of reference numerals is as follows:

1-reference point; 2-distribution type fiber-optic; 3-monitoring point; 4-concrete bed; 5-fixed support; 6-sleeve pipe; 7-hollow circular-tube; 8-stops plug; 9-epoxide-resin glue; 10-groove; 11-1 optical fiber; 12-2 optical fiber; 13-3 optical fiber.

Embodiment

Below in conjunction with accompanying drawing and specific embodiment, device and method of the present invention is described in further detail:

See Fig. 1, Fig. 2 and Fig. 3, the invention provides a kind of Characters in Tunnel Surface Settlement monitoring device based on distributing optical fiber sensing, this device mainly comprises reference point 1, distribution type fiber-optic 2, monitoring point 3; Reference point 1 mainly comprises concrete bed 4, fixed support 5, sleeve pipe 6, hollow circular-tube 7, only plug 8 and epoxide-resin glue 9, and reference point 1 is laid in the position apart from tunnel axis horizontal range 3 ~ 5 Bei Dong footpath; Monitoring point 3 with tunnel axis be axle symmetrically shape equidistantly distribute; Fixed support 5 and concrete bed 4 is provided with below sleeve pipe 6; It is inner that hollow circular-tube 7 is fixed on sleeve pipe 6, the inwall of hollow circular-tube 7 is provided with 3 grooves 10 (the first groove, the second groove and the 3rd groove), angle between first groove and second groove, the 3rd groove is respectively 180 °, 90 °, lays 1 distribution type fiber-optic 2 in each groove 10; Hollow circular-tube 7 two ends are provided with only plug 8; Epoxide-resin glue 9 is injected in hollow circular-tube 7 inside, distribution type fiber-optic 2 and hollow circular-tube 7 is bonded as one.

Distribution type fiber-optic 2 is hard-pressed bale sheath straining and sensing optical cable, uses polyurethane elastomeric materials packaging protection outside its fibre core, and this optic cable diameter is 2mm, and weight is 2kg/km.

Concrete bed 4 longitudinal cross-section is trapezoidal, and upper bottom side length is 40cm, and the length of side of going to the bottom is 20cm, and be highly 50cm, its buried depth is not less than 1.5m.

Hollow circular-tube 7 length is 10cm, and external diameter is 6cm, and internal diameter is 5cm, is provided with 3 grooves 10 inside it, and groove 10 cross sectional dimensions is 3mm × 3mm; When laying distribution type fiber-optic 2 in groove 10, should ensure that the line of No. 1 optical fiber 11, No. 2 optical fiber 12 is vertical with No. 3 optical fiber 13.

Present invention also offers a kind of Characters in Tunnel Surface Settlement monitoring device construction method based on distributing optical fiber sensing, the steps include:

A (), at the earth's surface place excavation pit apart from tunnel axis horizontal range 3 ~ 5 Bei Dong footpath, casting concrete base 4, and mounting and fixing bracket 5, subsequently at fixed support 5 upper weld sleeve pipe 6;

B hollow circular-tube 7 is fixed on sleeve pipe 6 by () inner, should ensure that hollow circular-tube 7 and sleeve pipe 6 bond firmly;

C 3 distribution type fiber-optics 2 embed in 3 grooves 10 in hollow circular-tube 7 by () respectively, install only plug 8 at hollow circular-tube 7 two ends, and inject epoxide-resin glue 9 to hollow circular-tube 7 inside, and reference point 1 has been laid;

D () lays monitoring point 3 according to step (a) ~ (c), make monitoring point 3 with tunnel axis be axle symmetrically shape equidistantly distribute.

Present invention also offers a kind of Characters in Tunnel Surface Settlement monitoring principle based on distributing optical fiber sensing and method, the steps include:

As shown in Figure 4, when a certain monitoring point produces with stratum, 3 fiber-optic monitorings to strain value be respectively ε ₁(x), ε ₂(x), ε ₃x (), because fibre strain value ε (x) is axial strain ε _a(x) and bending strain ε _b(x) sum, that is:

ε(x)＝ε _a(x)+ε _b(x)(1)

Can obtain according to geometric relationship:

ε _b(x)＝-Rcos(θ)/ρ(x)(2)

Wherein x is certain some horizontal range to reference point on optical fiber; R is hollow circular-tube external diameter, and θ is the angle between 1, No. 2 optical fiber line and horizontal direction, the radius-of-curvature that ρ (x) is fibre-optical bending.

Because ε (x) is with ε _a(x) for axle be cosine fluctuation, and 1, No. 2 optical fiber symmetrically shape distribution, therefore can obtain:

${\mathrm{\ϵ}}_a\left(x\right)=\frac{{\mathrm{\ϵ}}_1\left(x\right)+{\mathrm{\ϵ}}_2\left(x\right)}{2}---\left(3\right)$

${\mathrm{\ϵ}}_b\left(x\right)=\frac{{\mathrm{\ϵ}}_1\left(x\right)-{\mathrm{\ϵ}}_2\left(x\right)}{2}---\left(4\right)$

Because No. 3 optical fiber are vertical with 1, No. 2 optical fiber line, then:

${\mathrm{\ϵ}}_3\left(x\right)={\mathrm{\ϵ}}_a\left(x\right)-\frac{Rsin\left(\mathrm{\θ}\right)}{\mathrm{\ρ}\left(x\right)}---\left(5\right)$

According to formula (5) known ε ₁(x), ε ₃x () is mutual remaining relation, then angle theta is:

$\mathrm{\θ}=arctan\frac{2{\mathrm{\ϵ}}_3\left(x\right)-{\mathrm{\ϵ}}_1\left(x\right)-{\mathrm{\ϵ}}_2\left(x\right)}{{\mathrm{\ϵ}}_1\left(x\right)-{\mathrm{\ϵ}}_2\left(x\right)}---\left(6\right)$

The vertical displacement Δ H of certain monitoring point is:

$\mathrm{\Δ}H={\∫}_0^L{\∫}_0^L\frac{1}{\mathrm{\ρ}\left(x\right)}dxdx---\left(7\right)$

In formula, L is the horizontal range between certain monitoring point and reference point; Therefore, formula (2), formula (6) are substituted into the subsidence value that can draw certain monitoring point in formula (7).

What finally illustrate is, above embodiment is only in order to illustrate technical scheme of the present invention and unrestricted, although with reference to most preferred embodiment to invention has been detailed description, those of ordinary skill in the art is to be understood that, can modify to technical scheme of the present invention or equivalent replacement, and not departing from aim and the scope of technical solution of the present invention, it all should be encompassed in the middle of right of the present invention.

Claims (7)

1. based on a Characters in Tunnel Surface Settlement monitoring device for distributing optical fiber sensing, it is characterized in that: the described Characters in Tunnel Surface Settlement monitoring device based on distributing optical fiber sensing comprises distribution type fiber-optic, be arranged on apart from the reference point in tunnel axis horizontal range 3 ~ 5 times of Tunnel footpaths and take tunnel axis as axle symmetrically multiple monitoring points of equidistantly distributing of shape; Described reference point and monitoring point are provided with mounting base, and described distribution type fiber-optic to be arranged in the mounting base of reference point and monitoring point and to be connected with monitoring point by reference point.

2. the Characters in Tunnel Surface Settlement monitoring device based on distributing optical fiber sensing according to claim 1, is characterized in that: described mounting base comprises concrete bed, fixed support, sleeve pipe and hollow circular-tube; Described casing pipe sleeve is contained in hollow circular-tube outside; The tube wall of described sleeve pipe is connected with concrete bed by fixed support; The inwall of described hollow circular-tube offers the first groove, the second groove and the 3rd groove; Angle between described first groove and the second groove and the 3rd groove is 180 ° and 90 ° respectively; A distribution type fiber-optic is laid with in described first groove, the second groove and the 3rd groove.

3. the Characters in Tunnel Surface Settlement monitoring device based on distributing optical fiber sensing according to claim 2, is characterized in that: described mounting base also comprises the epoxide-resin glue be filled in hollow circular-tube and the only plug being arranged on hollow circular-tube both ends.

4. the Characters in Tunnel Surface Settlement monitoring device based on distributing optical fiber sensing according to claim 3, it is characterized in that: the longitudinal cross-section of described concrete bed is trapezoidal, the upper bottom side length of described concrete bed is not more than 40cm, the bottom of described concrete bed is failed to grow up in 20cm, the height of described concrete bed is not more than 50cm, and the buried depth of described concrete bed is not less than 1.5m.

5. the Characters in Tunnel Surface Settlement monitoring device based on distributing optical fiber sensing according to claim 4, it is characterized in that: the length of described hollow circular-tube is not more than 10cm, the external diameter of described hollow circular-tube is not more than 6cm, the internal diameter of described hollow circular-tube is not more than 5cm, and the cross sectional dimensions of the first groove that described hollow circular-tube inwall is offered, the second groove and the 3rd groove is 3mm × 3mm.

6. the Characters in Tunnel Surface Settlement monitoring device based on distributing optical fiber sensing according to the arbitrary claim of claim 1-5; it is characterized in that: described distribution type fiber-optic is hard-pressed bale sheath straining and sensing optical cable; polyurethane elastomeric materials protective seam is packaged with outside the fibre core of described distribution type fiber-optic; the diameter of described distribution type fiber-optic is 2mm, and weight is 2kg/km.

7., based on a monitoring method for the Characters in Tunnel Surface Settlement monitoring device based on distributing optical fiber sensing as claimed in claim 6, it is characterized in that: described monitoring method comprises the following steps:

1) at the earth's surface place excavation pit apart from tunnel axis horizontal range 3 ~ 5 Bei Dong footpath, casting concrete base, mounting and fixing bracket, at fixed support upper weld sleeve pipe;

2) hollow circular-tube be fixed on inside pipe casing and make hollow circular-tube and sleeve pipe bond firmly;

3) 3 distribution type fiber-optics are embedded respectively in the first groove, the second groove and the 3rd groove in hollow circular-tube, only plug is installed at hollow circular-tube two ends, inject epoxide-resin glue to hollow circular-tube inside, complete the laying of reference point;

4) according to step 1) ~ step 3) described method lays monitoring point, described monitoring point with tunnel axis be axle symmetrically shape equidistantly distribute;

5) carry out Real-Time Monitoring to Characters in Tunnel Surface Settlement, the specific implementation of described monitoring method is:

When a certain monitoring point with stratum produce sink time, be laid in respectively the first optical fiber in the first groove of hollow circular-tube inwall, the second groove and the 3rd groove, the second optical fiber and the 3rd fiber-optic monitoring to strain value be respectively ε ₁(x), ε ₂(x), ε ₃x (), fibre strain value ε (x) is axial strain ε _a(x) and bending strain ε _b(x) sum, that is:

ε(x)＝ε _a(x)+ε _b(x)(1)

Can obtain according to geometric relationship:

ε _b(x)＝-Rcos(θ)/ρ(x)(2)

Wherein:

X is certain some horizontal range to reference point on optical fiber;

R is the external diameter of hollow circular-tube;

θ is the angle between the line of the first optical fiber and the second optical fiber and horizontal direction;

The radius-of-curvature that ρ (x) is fibre-optical bending;

ε (x) is with ε _a(x) for axle be cosine fluctuation, and the first optical fiber and the second optical fiber symmetrically shape distribute, therefore can obtain:

${\mathrm{\ϵ}}_a\left(x\right)=\frac{{\mathrm{\ϵ}}_1\left(x\right)+{\mathrm{\ϵ}}_2\left(x\right)}{2}---\left(3\right)$

${\mathrm{\ϵ}}_b\left(x\right)=\frac{{\mathrm{\ϵ}}_1\left(x\right)-{\mathrm{\ϵ}}_2\left(x\right)}{2}---\left(4\right)$

The line of the 3rd optical fiber and the first optical fiber and the second optical fiber is perpendicular, then:

${\mathrm{\ϵ}}_3\left(x\right)={\mathrm{\ϵ}}_a\left(x\right)-\frac{Rsin\left(\mathrm{\θ}\right)}{\mathrm{\ρ}\left(x\right)}---\left(5\right)$

According to formula (5) known ε ₁(x), ε ₃x () is mutual remaining relation, then angle theta is:

$\mathrm{\θ}=arctan\frac{2{\mathrm{\ϵ}}_3\left(x\right)-{\mathrm{\ϵ}}_1\left(x\right)-{\mathrm{\ϵ}}_2\left(x\right)}{{\mathrm{\ϵ}}_1\left(x\right)-{\mathrm{\ϵ}}_2\left(x\right)}---\left(6\right)$

The vertical displacement Δ H of the monitoring point that should sink with stratum generation is:

$\mathrm{\Δ}H={\∫}_0^L{\∫}_0^L\frac{1}{\mathrm{\ρ}\left(x\right)}dxdx---\left(7\right)$

Wherein: L be with stratum produce sink monitoring point and reference point between horizontal range;

Formula (2), formula (6) are substituted into the subsidence value that can draw in formula (7) and produce the monitoring point sunk with stratum.