阅读说明：本技术 基于光纤传感技术的地表沉降准分布式监测装置及方法 (Surface subsidence quasi-distributed monitoring device and method based on optical fiber sensing technology ) 是由 夏开文 董鹏 徐颖 张开雨 赵玺 于 2019-10-24 设计创作，主要内容包括：本发明公开了一种基于光纤传感技术的地表沉降准分布式监测装置及方法,包括准分布式沉降监测站点、分布式光纤定点传感线路、PPP-BOTDA光纤数据采集仪和数据处理系统。每个所述准分布式沉降监测站点上布置定点锚固支架；所述分布式光纤定点传感线路包括分布式光纤进、回线部分,两部分分布式光纤均固定在定点锚固支架上；所述分布式光纤进线部分呈锯齿状布置,且,位于相邻两个定点锚固支架之间的分布式光纤进线部分的分布式光纤呈预拉伸状态；位于相邻两个定点锚固支架之间的分布式光纤回线部分的分布式光纤呈松弛状态。本发明在满足空间分辨率的条件下,既扩大了监测范围,又保证了监测精度,弥补了以往监测技术效率低、空间分辨率低、精度低的不足。(The invention discloses a surface subsidence quasi-distributed monitoring device and method based on an optical fiber sensing technology. A fixed-point anchoring support is arranged on each quasi-distributed settlement monitoring station; the distributed optical fiber fixed point sensing line comprises a distributed optical fiber incoming line part and a distributed optical fiber return line part, and the two parts of distributed optical fibers are fixed on the fixed point anchoring support; the distributed optical fiber incoming line part is arranged in a zigzag manner, and the distributed optical fiber of the distributed optical fiber incoming line part positioned between two adjacent fixed point anchoring brackets is in a pre-stretched state; the distributed optical fiber of the distributed optical fiber loop part positioned between two adjacent fixed point anchoring brackets is in a relaxed state. Under the condition of meeting the spatial resolution, the invention not only expands the monitoring range, but also ensures the monitoring precision, and makes up the defects of low efficiency, low spatial resolution and low precision of the traditional monitoring technology.)

1. The utility model provides a surface subsidence quasi-distributed monitoring devices based on optical fiber sensing technology which characterized in that includes:

quasi-distributed settlement monitoring sites which are arranged at intervals in a monitoring area, and a fixed-point anchoring support (1) is arranged on each quasi-distributed settlement monitoring site;

the distributed optical fiber fixed point sensing circuit comprises a distributed optical fiber incoming line part (3) and a distributed optical fiber return line part (4), wherein distributed optical fibers of the distributed optical fiber incoming line part (3) and the distributed optical fiber return line part (4) are fixed on the fixed point anchoring support (1); the distributed optical fiber incoming line parts (3) are arranged in a zigzag manner, and the distributed optical fibers of the distributed optical fiber incoming line parts (3) positioned between two adjacent fixed point anchoring supports (1) are in a pre-stretched state; the distributed optical fiber of the distributed optical fiber loop part (4) positioned between two adjacent fixed point anchoring supports (1) is in a relaxed state;

the distributed optical fiber incoming line part (3) and the distributed optical fiber return line part (4) are connected with the PPP-BOTDA optical fiber data acquisition instrument (5); and the number of the first and second groups,

and the PPP-BOTDA optical fiber data acquisition instrument (5) is connected with the data processing system.

2. The ground surface settlement quasi-distributed monitoring device based on the optical fiber sensing technology as claimed in claim 1, wherein the distributed optical fibers of the distributed optical fiber incoming line part (3) are fixedly connected to the fixed point anchoring support (1) through fixing clamps (2), and the difference between the height of the fixing clamp (2) on the quasi-distributed settlement monitoring station with even number and the height of the fixing clamp (2) on the quasi-distributed settlement monitoring station with odd number is 10cm, so that the distributed optical fiber incoming line part (3) is arranged in a zigzag manner.

3. The device for quasi-distributed monitoring of surface subsidence based on optical fiber sensing technology according to claim 2, wherein the fixing clamp (2) comprises:

the U-shaped clamp comprises a U-shaped clamp body, wherein the U-shaped clamp body comprises two clamping sections and an optical fiber pasting section (2-2), and the two clamping sections are respectively positioned on two sides of the optical fiber pasting section (2-2); the two clamping sections are clamped at two sides of the fixed point anchoring bracket (1); the distributed optical fibers of the distributed optical fiber incoming line part (3) are adhered to the optical fiber adhering sections (2-2);

the fixing screw (2-1), the said fixing screw (2-1) is connected to one of said grip segments, is used for fixing the said U-shaped clamp body on the said fixed point anchor support (1); and the number of the first and second groups,

the arc transition sections (2-3) are arranged on two sides of the optical fiber pasting section (2-2) and used for preventing distributed optical fibers of the distributed optical fiber incoming line part (3) from being bent.

4. The optical fiber sensing technology-based surface subsidence quasi-distributed monitoring device of claim 1, wherein the quasi-distributed subsidence monitoring stations are arranged one by one at intervals of 1m along a straight line in a monitoring area.

5. The monitoring method of the surface subsidence quasi-distributed monitoring device based on the optical fiber sensing technology is characterized by comprising the following steps of:

step a, site arrangement: arranging a series of fixed point anchoring supports (1) in a monitoring area to form a quasi-distributed settlement monitoring station;

step b, optical fiber pasting: connecting the distributed optical fiber with each fixed point anchoring support (1), and respectively arranging a distributed optical fiber incoming line part (3) and a distributed optical fiber return line part (4) of the distributed optical fiber fixed point sensing line;

step c, strain monitoring: and a PPP-BOTDA optical fiber data acquisition instrument (5) is adopted to monitor the strain change condition on the distributed optical fiber fixed point sensing line in real time and calculate the surface subsidence.

6. The monitoring method of the surface subsidence quasi-distributed monitoring device based on the optical fiber sensing technology is characterized in that in the step a, the method for arranging the fixed-point anchoring bracket (1) comprises the following steps:

step a1, in the monitoring area, selecting the measuring point position every 1m along the straight line;

step a2, implanting the tail end of each fixed point anchoring bracket (1) below the ground at the selected measuring point position to form a quasi-distributed settlement monitoring station.

7. The monitoring method of the surface subsidence quasi-distributed monitoring device based on the optical fiber sensing technology as claimed in claim 6, wherein in the step a2, the implantation depth of each fixed point anchoring bracket (1) is 30cm-40cm, and the surface exposure length is 30cm-40 cm.

8. The method according to claim 6, wherein in step b, the distributed optical fiber fixed-point sensing line is arranged by a method comprising:

b1, respectively installing a fixing clamp (2) on each fixed point anchoring support (1), and keeping each fixing clamp (2) at a uniform horizontal height;

b2, pasting the distributed optical fibers of the distributed optical fiber incoming line part (3) on the fixing clamp (2) at a fixed point, and keeping the distributed optical fibers of the distributed optical fiber incoming line part (3) in a prestretched state in the pasting process;

b3, adjusting the height of the fixing clamp (2) to ensure that the difference between the height of the fixing clamp (2) on the even number quasi-distributed settlement monitoring station and the height of the fixing clamp (2) on the odd number quasi-distributed settlement monitoring station is 10cm, and ensuring that the distributed optical fiber incoming line part (3) is arranged in a zigzag manner;

and b4, directly sticking the distributed optical fiber of the distributed optical fiber loop part (4) on the fixed point anchoring bracket (1) to keep the distributed optical fiber of the distributed optical fiber loop part (4) in a loose state.

9. The method for monitoring the surface subsidence quasi-distributed monitoring device based on the optical fiber sensing technology as claimed in claim 6, wherein in the step c, the method for calculating the surface subsidence is as follows:

step c1, any number one quasi-distributed settlement monitoring according to the geometric principleSettlement delta H of measuring station relative to former quasi-distributed settlement monitoring station_i,(i-1)Comprises the following steps:

in the formula, H_iThe initial sawtooth height of the distributed optical fiber incoming line part (3) in a sawtooth arrangement; l is the horizontal spacing of the quasi-distributed settlement monitoring stations; setting the distributed optical fiber between any one quasi-distributed settlement monitoring station and the previous quasi-distributed settlement monitoring station as the ith cross optical fiber, epsilon_iIs the strain change across the fiber;

step c2, assuming that each quasi-distributed settlement monitoring station only generates settlement displacement in the vertical direction, and calculating the settlement of each quasi-distributed settlement monitoring station relative to the No. 0 quasi-distributed settlement monitoring station according to a formula (2):

in the formula,. DELTA.H_N,0And the settlement of the Nth quasi-distributed settlement monitoring station relative to the 0 th quasi-distributed settlement monitoring station is obtained.

Technical Field

The invention relates to a geotechnical engineering monitoring technology, in particular to a surface subsidence quasi-distributed monitoring device and method based on an optical fiber sensing technology.

Background

The ground surface settlement can be caused by the construction of foundation pits and underground engineering, energy exploitation, underground water extraction and foundation consolidation settlement, and the safety, stability and healthy operation of ground surface building facilities and traffic pipelines are influenced. The monitoring of the surface subsidence is an important link for monitoring the construction safety of shallow underground engineering and foundation pit engineering, and also provides an important basis for evaluating the safety and stability of surface buildings and the healthy operation of traffic pipelines. Accurate and real-time surface settlement monitoring can provide necessary conditions for ensuring shallow underground engineering, safe construction of foundation pit engineering and early warning of disasters. Because the traditional earth surface monitoring method is mainly spot-collecting monitoring, the spatial resolution is insufficient, the workload is large, and the requirement of real-time monitoring cannot be met.

Brillouin Optical Time Domain Analysis (BOTDA) is a distributed optical fiber sensing technology with wide application prospect. The Brillouin scattering is affected by strain and temperature at the same time, when the temperature along the optical fiber changes or has strain, the frequency of the back Brillouin scattering light in the optical fiber shifts, and the shift amount of the frequency and the strain and the temperature change of the optical fiber have a good linear relation, so that the distribution information of the temperature and the strain along the optical fiber can be obtained by measuring the frequency shift amount of the back natural Brillouin scattering light in the optical fiber. Based on the BOTDA technology, the pre-pulse pumping Brillouin optical time domain analysis (PPP-BOTDA) based on the Brillouin scattering principle improves the spatial resolution (2cm) and the precision (5 mu epsilon) and has more obvious advantages.

At present, the existing earth surface settlement monitoring method based on the distributed optical fiber sensing technology mainly utilizes an elastic beam model to perform double integration on the variation under the condition of selecting a proper boundary so as to obtain settlement values at various positions. However, due to the error of the strain, the measured sinking value error is large when the integral distance is long. The invention provides a surface subsidence quasi-distributed monitoring method based on an optical fiber sensing technology, which not only expands the monitoring range but also ensures the monitoring precision under the condition of meeting the spatial resolution, and overcomes the defects of low efficiency, low spatial resolution and low precision of the traditional monitoring technology.

Disclosure of Invention

The invention provides a surface subsidence quasi-distributed monitoring device and method based on an optical fiber sensing technology, aiming at the defects of a conventional monitoring means and a conventional distributed optical fiber monitoring method, the monitoring range is expanded, the monitoring precision is ensured under the condition of meeting the spatial resolution, and the defects of low efficiency, low spatial resolution and low precision of the conventional monitoring technology are overcome.

The technical scheme adopted by the invention is as follows: a quasi-distributed monitoring device for surface subsidence based on optical fiber sensing technology comprises:

the system comprises quasi-distributed settlement monitoring stations, wherein the quasi-distributed settlement monitoring stations are arranged in a monitoring area at intervals, and fixed-point anchoring supports are arranged on each quasi-distributed settlement monitoring station;

the distributed optical fiber fixed point sensing circuit comprises a distributed optical fiber incoming line part and a distributed optical fiber return line part, and distributed optical fibers of the distributed optical fiber incoming line part and the distributed optical fiber return line part are fixed on the fixed point anchoring support; the distributed optical fiber incoming line part is arranged in a zigzag manner, and the distributed optical fiber of the distributed optical fiber incoming line part positioned between two adjacent fixed point anchoring brackets is in a pre-stretched state; the distributed optical fiber of the distributed optical fiber loop part positioned between two adjacent fixed point anchoring brackets is in a relaxed state;

the ends of the distributed optical fiber incoming line part and the distributed optical fiber return line part are connected with the PPP-BOTDA optical fiber data acquisition instrument; and the number of the first and second groups,

and the PPP-BOTDA optical fiber data acquisition instrument is connected with the data processing system.

Furthermore, the distributed optical fibers of the distributed optical fiber incoming line part are fixedly connected to the fixed point anchoring support through fixing clamps, the height difference between the height of the fixing clamp on the quasi-distributed settlement monitoring station in an even number and the height of the fixing clamp on the quasi-distributed settlement monitoring station in an odd number is 10cm, and therefore the distributed optical fiber incoming line part is arranged in a zigzag mode.

Wherein, the mounting fixture includes:

the U-shaped clamp comprises a U-shaped clamp body, wherein the U-shaped clamp body comprises two clamping sections and an optical fiber pasting section, and the two clamping sections are respectively positioned on two sides of the optical fiber pasting section; the two clamping sections are clamped at two sides of the fixed point anchoring bracket; the distributed optical fibers of the distributed optical fiber incoming line part are pasted on the optical fiber pasting section;

the fixing screw is connected to one of the clamping sections and used for fixing the U-shaped clamp body on the fixed point anchoring support; and the number of the first and second groups,

and the arc transition sections are arranged on two sides of the optical fiber pasting section and used for preventing the distributed optical fibers of the distributed optical fiber incoming line part from being bent.

Further, the quasi-distributed settlement monitoring stations are arranged in the monitoring area at intervals of 1m along a straight line.

The other technical scheme adopted by the invention is as follows: the monitoring method of the surface subsidence quasi-distributed monitoring device based on the optical fiber sensing technology comprises the following steps:

step a, site arrangement: arranging a series of fixed point anchoring supports in a monitoring area to form a quasi-distributed settlement monitoring station;

step b, optical fiber pasting: connecting the distributed optical fiber with each fixed point anchoring support, and respectively arranging a distributed optical fiber incoming line part and a distributed optical fiber return line part of the distributed optical fiber fixed point sensing circuit;

step c, strain monitoring: and monitoring the strain change condition on the distributed optical fiber fixed point sensing line in real time by adopting a PPP-BOTDA optical fiber data acquisition instrument, and calculating the surface settlement.

Further, in step a, the method for arranging the fixed point anchoring stent comprises the following steps:

step a1, in the monitoring area, selecting the measuring point position every 1m along the straight line;

step a2, implanting the tail end of each fixed point anchoring bracket into the ground at the selected measuring point position to form a quasi-distributed settlement monitoring station.

Further, in step a2, each of the fixed point anchor stents has an implantation depth of 30cm-40cm and a surface exposure length of 30cm-40 cm.

Further, in step b, the method for arranging the distributed optical fiber fixed point sensing line includes:

b1, respectively installing a fixing clamp on each fixed point anchoring bracket, wherein each fixing clamp is kept at a uniform horizontal height;

b2, pasting the distributed optical fibers of the distributed optical fiber incoming line part on a fixing clamp at a fixed point, and keeping the distributed optical fibers of the distributed optical fiber incoming line part in a prestretched state in the pasting process;

b3, adjusting the height of the fixing clamp to ensure that the difference between the height of the fixing clamp on the even number quasi-distributed settlement monitoring station and the height of the fixing clamp on the odd number quasi-distributed settlement monitoring station is 10cm, so that the distributed optical fiber incoming line part is arranged in a zigzag manner;

and b4, directly sticking the distributed optical fiber of the distributed optical fiber loop part on the fixed point anchoring bracket, and keeping the distributed optical fiber of the distributed optical fiber loop part in a loose state.

Further, in step c, the method for calculating the surface subsidence comprises the following steps:

step c1, according to the geometric principle, the settlement delta H of any one quasi-distributed settlement monitoring station relative to the previous quasi-distributed settlement monitoring station_i,(i-1)Comprises the following steps:

in the formula, H_iThe initial sawtooth height of the distributed optical fiber incoming line part in a sawtooth arrangement; l is the horizontal spacing of the quasi-distributed settlement monitoring stations; setting the distributed optical fiber between any one quasi-distributed settlement monitoring station and the previous quasi-distributed settlement monitoring station as the ith cross optical fiber, epsilon_iIs the strain change across the fiber;

step c2, assuming that each quasi-distributed settlement monitoring station only generates settlement displacement in the vertical direction, and calculating the settlement of each quasi-distributed settlement monitoring station relative to the No. 0 quasi-distributed settlement monitoring station according to a formula (2):

in the formula,. DELTA.H_N,0And the settlement of the Nth quasi-distributed settlement monitoring station relative to the 0 th quasi-distributed settlement monitoring station is obtained.

The invention has the beneficial effects that: the invention provides a quasi-distributed monitoring device and method for surface subsidence based on an optical fiber sensing technology, which can accurately monitor the surface subsidence of the surface caused by various reasons. The method has the first advantage that quasi-distributed settlement monitoring can be realized, and the spatial resolution can reach 1m, which is superior to the traditional monitoring method; the second advantage is that high-precision measurement is realized, and the relative settlement precision between adjacent monitoring stations can reach 0.1 mm; the third advantage is that the characteristics of the distributed optical fiber sensing technology are utilized to realize remote and high-efficiency real-time monitoring and reduce the monitoring cost; the fourth advantage is that the optical fiber and optical signal are safe and reliable, anti-electromagnetic interference, good electrical insulation, corrosion resistance and the like, and the optical fiber and optical signal monitoring device is suitable for long-term monitoring.

Drawings

FIG. 1: the invention discloses a distributed optical fiber fixed-point arrangement schematic diagram;

FIG. 2: the structure of the fixing clamp is schematic;

the attached drawings are marked as follows: 1. the device comprises a fixed point anchoring support, 2 parts of a fixing clamp, 2-1 parts of a fixing screw, 2-2 parts of an optical fiber pasting section, 2-3 parts of an arc transition section, 3 parts of a distributed optical fiber incoming line part, 4 parts of a distributed optical fiber return line part and 5 parts of a PPP-BOTDA optical fiber data acquisition instrument.

Detailed Description

In order to further understand the contents, features and effects of the present invention, the following embodiments are illustrated and described in detail with reference to the accompanying drawings:

the monitoring device comprises a fixed point anchoring support 1, a fixing clamp 2, a distributed optical fiber, a Brillouin optical time domain analysis technology (PPP-BOTDA optical fiber data acquisition instrument 5) and a data processing system. The distributed optical fiber is connected with the fixing clamp 2 in a glue injection mode, the fixing clamp 2 is installed on the fixed point anchoring support 1, and the distributed fixed point sensing optical cable arranged in a zigzag mode is formed by changing the horizontal height of the fixing clamp 2. The relative settlement monitoring of the adjacent fixed point anchoring supports 1 is realized by monitoring the strain change of the optical fiber between the adjacent fixed point anchoring supports 1, so that the settlement information of each fixed point support can be obtained.

As shown in fig. 1 and fig. 2, a quasi-distributed monitoring device for surface subsidence based on optical fiber sensing technology includes quasi-distributed subsidence monitoring stations, distributed optical fiber fixed-point sensing lines, a PPP-BOTDA optical fiber data acquisition instrument 5 and a data processing system.

The quasi-distributed settlement monitoring stations are arranged at intervals of 1m in a monitoring area, and fixed-point anchoring supports 1 are arranged on each quasi-distributed settlement monitoring station.

Distributed optical fiber fixed point sensing line includes distributed optical fiber inlet wire part 3 and distributed optical fiber return wire part 4, distributed optical fiber of distributed optical fiber inlet wire part 3 passes through mounting fixture 2 fixed connection in fixed point anchor support 1 is even number on the accurate distributed subsides monitoring site mounting fixture 2's height is than the odd number on the accurate distributed subsides monitoring site mounting fixture 2's height is 10cm low, makes distributed optical fiber inlet wire part 3 is the zigzag and arranges. The fixing clamp 2 comprises a U-shaped clamp body, a fixing screw 2-1 and an arc transition section 2-3, the U-shaped clamp body comprises two clamping sections and an optical fiber pasting section 2-2, and the two clamping sections are respectively positioned on two sides of the optical fiber pasting section 2-2; the two clamping sections are clamped at two sides of the fixed point anchoring bracket 1; the distributed optical fibers of the distributed optical fiber incoming line part 3 are pasted on the optical fiber pasting sections 2-2; the fixing screw 2-1 is connected to one of the clamping sections and used for fixing the U-shaped clamp body on the fixed point anchoring support 1; the arc transition sections 2-3 are arranged on two sides of the optical fiber pasting section 2-2 and used for preventing the distributed optical fibers of the distributed optical fiber incoming line part 3 from being bent. The distributed optical fiber of the distributed optical fiber loop part 4 is directly adhered to the fixed point anchoring bracket 1. The distributed optical fibers of the distributed optical fiber incoming line part 3 positioned between two adjacent fixed point anchoring brackets 1 are in a pre-stretched state; the distributed optical fiber of the distributed optical fiber loop part 4 positioned between two adjacent fixed point anchoring supports 1 is in a relaxed state.

The end parts of the distributed optical fiber incoming line part 3 and the distributed optical fiber return line part 4 are connected with the PPP-BOTDA optical fiber data acquisition instrument 5.

The PPP-BOTDA optical fiber data acquisition instrument 5 is connected with the data processing system.

The method for monitoring the surface subsidence quasi-distributed monitoring device based on the optical fiber sensing technology comprises the following steps:

step a, in a monitoring area, selecting measuring point positions every 1m along a straight line, arranging a series of fixed point anchoring supports 1 in the monitoring area at the selected measuring point positions, implanting the tail ends of the fixed point anchoring supports below the ground, wherein the implantation depth is 50cm, anchoring the fixed point anchoring supports, and exposing the top ends of the fixed point anchoring supports to the ground surface for 30-40cm, so as to form a quasi-distributed settlement monitoring station.

B, mounting the fixed clamps 2 on the fixed point anchoring supports 1, and keeping the fixed clamps 2 at a uniform horizontal height; the fixed clamp 2 is connected with the fixed point anchoring support 1 through a fixed screw 2-1; the fixing clamp 2 consists of an optical fiber pasting section 2-2 and an arc transition section 2-3; as shown in fig. 2.

And c, sticking the distributed optical fibers of the distributed optical fiber incoming line part 3 on the optical fiber sticking section 2-2 of the fixing clamp 2 at fixed points by using epoxy resin glue, and keeping the distributed optical fibers of the distributed optical fiber incoming line part 3 in a certain pre-stretching state in the sticking process.

D, adjusting the height of the fixed clamp 2, and reducing the height of the fixed clamp 2 on the even-numbered (second, fourth, sixth and … …) quasi-distributed settlement monitoring station by 10cm, so that the difference between the height of the fixed clamp 2 on the even-numbered quasi-distributed settlement monitoring station and the height of the fixed clamp 2 on the odd-numbered quasi-distributed settlement monitoring station is 10cm, the wire inlet part of the distributed optical fiber fixed point sensing line is arranged in a zigzag manner, and the height of the zigzag is 10 cm; as shown in fig. 1.

Step e, directly sticking the distributed optical fiber of the distributed optical fiber loop part 4 on the fixed point anchoring bracket 1, and keeping the distributed optical fiber of the distributed optical fiber loop part 4 in a loose state; as shown in fig. 1.

And f, connecting the distributed optical fiber incoming line part 3 and the distributed optical fiber return line part 4 to a PPP-BOTDA optical fiber data acquisition instrument 5, acquiring optical fiber strain signals, and monitoring the strain change condition on the distributed optical fiber fixed point sensing line in real time.

Step g, calculating the surface subsidence:

according to the geometric principle, the settlement delta H of any one quasi-distributed settlement monitoring station relative to the previous quasi-distributed settlement monitoring station_i,(i-1)Comprises the following steps:

in the formula, H_iThe initial sawtooth height of the distributed optical fiber fixed point sensing circuit which is arranged in a sawtooth shape; l is the horizontal spacing of the quasi-distributed settlement monitoring stations; setting the optical fiber between any one quasi-distributed settlement monitoring station and the previous quasi-distributed settlement monitoring station as the ith cross optical fiber, epsilon_iIs the strain change across the fiber;

assuming that each quasi-distributed settlement monitoring station only generates settlement displacement in the vertical direction, and calculating the settlement of each quasi-distributed settlement monitoring station relative to the No. 0 quasi-distributed settlement monitoring station according to a formula (2):

in the formula,. DELTA.H_N,0And the settlement of the Nth quasi-distributed settlement monitoring station relative to the 0 th quasi-distributed settlement monitoring station is obtained.

The invention discloses a surface subsidence quasi-distributed monitoring device and method based on an optical fiber sensing technology, and the principle is as follows: when the surface subsides, drive the fixed point anchor support 1 of quasi-distributed settlement monitoring station and produce and subside, through testing distributed optical fiber inlet wire part 3 and the distributed optical fiber return wire part 4 strain variation value of loosely arranged of zigzag arrangement, obtain the tensile or shrink length of optic fibre between the adjacent quasi-distributed settlement monitoring station, adopt data processing system to realize the timely analysis of data and the settlement calculation of quasi-distributed measurement station surface.

The invention has the characteristics of quasi-distribution, high precision and large measurement range, and is suitable for monitoring the harmful settlement of the earth surface caused by underground engineering construction, energy exploitation, underground water extraction, foundation consolidation and the like.

Although the preferred embodiments of the present invention have been described above with reference to the accompanying drawings, the present invention is not limited to the above-described embodiments, which are merely illustrative and not restrictive, and those skilled in the art can make many modifications without departing from the spirit and scope of the present invention as defined in the appended claims.