阅读说明：本技术 基于光栅阵列的冻土路基变形场优化监测设备与方法 (Frozen soil roadbed deformation field optimization monitoring equipment and method based on grating array ) 是由 李震 富志鹏 赵力国 董长松 李博融 袁堃 苟超 于 2021-05-28 设计创作，主要内容包括：本发明涉及基于光栅阵列的冻土路基变形场优化监测设备,其高压液压管横向埋置于道路路基中并分节段布置,高精度光栅光纤压力传感器通过卡箍式三通设置在各节段的高压液压管之间令高压液压管形成密封管体,高压液压管中充注有防冻液；基准传感器和光纤解调仪设置于道路路基外侧,基准传感器设置在高压液压管终止端,高精度光栅光纤压力传感器和基准传感器通过铠装连接光纤依次连接并接入光纤解调仪。当土体沉降时,通过沉降盒与基准位置之间的液位压差反算出相对高差的变化,得到相对沉降变形,能在合理预测精确度与有限成本范围内,实现面向区域化、韧性化、自动化的冻土路基变形场监测技术,实时掌握冻土路基不均匀沉降的演化规律与发展趋势。(The invention relates to frozen soil roadbed deformation field optimization monitoring equipment based on a grating array, wherein a high-pressure hydraulic pipe is transversely embedded in a road roadbed and is arranged in sections, a high-precision grating optical fiber pressure sensor is arranged between the high-pressure hydraulic pipes of all the sections through a clamp type tee joint so that the high-pressure hydraulic pipes form a sealed pipe body, and anti-freezing liquid is filled in the high-pressure hydraulic pipes; the reference sensor and the optical fiber demodulator are arranged on the outer side of a road bed, the reference sensor is arranged at the termination end of the high-pressure hydraulic pipe, and the high-precision grating optical fiber pressure sensor and the reference sensor are sequentially connected with each other through armored connection optical fibers and are connected into the optical fiber demodulator. When the soil body subsides, the change of relative discrepancy in elevation is calculated back through the liquid level pressure differential between settlement box and the reference position, obtains the relative settlement deformation, can be in reasonable prediction accuracy and limited cost range, realizes the frozen soil roadbed deformation field monitoring technology towards regionalization, toughness ization, automation, masters the evolution law and the development trend of frozen soil roadbed differential settlement in real time.)

1. Frozen soil roadbed deformation field optimization monitoring facilities based on grating array, its characterized in that:

the device comprises a high-pressure hydraulic pipe (1), a high-precision grating optical fiber pressure sensor (2), an armored connecting optical fiber (7), a reference sensor (9) and an optical fiber demodulator (13);

the high-pressure hydraulic pipes (1) are transversely embedded in a road bed (11) and are arranged in sections, the high-precision grating optical fiber pressure sensors (2) are arranged among the high-pressure hydraulic pipes (1) of each section through the clamp type tee joints (3) to enable the high-pressure hydraulic pipes (1) to form a sealed pipe body, and anti-freezing liquid is filled in the high-pressure hydraulic pipes (1);

the reference sensor (9) and the optical fiber demodulator (13) are arranged on the outer side of the road bed (11), the reference sensor (9) is arranged at the termination end of the high-pressure hydraulic pipe (1), and the high-precision grating optical fiber pressure sensor (2) and the reference sensor (9) are sequentially connected and connected into the optical fiber demodulator (13) through the armored connection optical fiber (7).

2. The frozen soil roadbed deformation field optimization monitoring equipment based on the grating array as claimed in claim 1, wherein:

the starting end of the high-pressure hydraulic pipe (1) is provided with a plug head (8), the reference sensor (9) is connected with the high-pressure hydraulic pipe (1) at the terminating end through a clamp type tee joint (3), and the other end of the clamp type tee joint (3) is provided with the plug head (8).

3. The frozen soil roadbed deformation field optimization monitoring equipment based on the grating array as claimed in claim 2, wherein:

the high-precision grating optical fiber pressure sensor (2) together with the high-pressure hydraulic pipe (1) and the armored connecting optical fiber (7) at the position of the high-precision grating optical fiber pressure sensor are packaged in the sedimentation box (4).

4. The frozen soil roadbed deformation field optimization monitoring equipment based on the grating array as claimed in claim 3, wherein:

a semi-annular buckle (10) for fixing the high-precision grating optical fiber pressure sensor (2) and the high-pressure hydraulic pipe (1) is arranged in the sedimentation box (4), and small rollers (19) are arranged on the upper side and the lower side of the high-pressure hydraulic pipe (1);

the two sides of the sedimentation box (4) are provided with high-pressure hydraulic pipes (1) and through holes for connecting the armored optical fibers (7), and the sedimentation box (4) is internally provided with a sedimentation box inner ribbed (21).

5. The frozen soil roadbed deformation field optimization monitoring equipment based on the grating array as claimed in claim 4, wherein:

PVC pipes (5) are arranged outside the high-pressure hydraulic pipes (1) and the armored connecting optical fibers (7) outside the sedimentation box (4), and redundant high-pressure hydraulic pipes (1) are coiled in a hydraulic pipe coil groove (6).

6. The frozen soil roadbed deformation field optimization monitoring equipment based on the grating array as claimed in claim 5, wherein:

the high-pressure hydraulic pipes (1) are transversely arranged in a plurality of ways in the roadbed, and each high-pressure hydraulic pipe (1) is connected with one termination end in a gathering way and is provided with one reference sensor (9);

the high-precision grating optical fiber pressure sensors (2) on the high-pressure hydraulic pipes (1) are connected into the same optical fiber demodulator (13) through armored connecting optical fibers (7) and FC/APC joints.

7. The frozen soil roadbed deformation field optimization monitoring equipment based on the grating array as claimed in claim 6, wherein:

the high-precision grating optical fiber pressure sensor (2) is transversely arranged at a distance of 2m and longitudinally arranged at a distance of 4-6 m.

8. The frozen soil roadbed deformation field optimization monitoring equipment based on the grating array as claimed in claim 7, wherein:

the reference sensor (9) is arranged on a concrete foundation (10) outside a road bed (11).

9. The optimized monitoring method for the frozen soil roadbed deformation field based on the grating array, which is implemented by the device of claim 8, is characterized in that:

the method comprises the following steps:

the method comprises the following steps: the starting end of a high-pressure hydraulic pipe (1) in the equipment is sealed and blocked by a plug head (8), and after anti-freezing liquid is injected into the ending end, a pipe body is subjected to a pipe body pressure test and then sealed and blocked by the plug head (8);

step two: one end of the armored connecting optical fiber (7) is connected into an optical fiber demodulator (13) through an FC/APC joint, the initial wavelength value of the embedded grating optical fiber is measured, the liquid level pressure of the embedded position of the high-precision grating optical fiber pressure sensor (2) is calculated, and then the liquid level difference of the position relative to a reference sensor (9) is calculated, namely the relative settlement deformation of the roadbed at the moment;

step three: and extracting the settlement deformation value of each measuring point position, and performing ordinary Kriging spatial interpolation interpretation to form a roadbed settlement deformation field at the measured elevation position.

10. The frozen soil roadbed deformation field optimized monitoring method based on the grating array as claimed in claim 9, wherein the method comprises the following steps:

the equipment arrangement process is as follows:

the method comprises the following steps: after the road subgrade (11) is constructed to the monitoring measurement elevation, the measurement is carried out along the cross section, and the specific position of the arrangement of the subgrade transverse and longitudinal grating array subgrade settlement monitoring sensing equipment is determined;

step two: excavating sensing equipment by a machine to lay ditch positions, wherein the excavation depth is 30cm, leveling the bottoms of the ditches, then filling 5cm of fine sand, and sequentially laying the sensing equipment of each transverse section;

step three: after the sensor equipment is laid, detecting the integrity of the armored connecting optical fiber (7) to ensure that the sensors are all alive;

step four: collecting the armored connecting optical fibers (7) and the high-pressure hydraulic pipes (1) at node positions, arranging reference sensors (9) at the node positions, pouring concrete foundations (10) at the positions of natural ground (12), fixing the reference sensors (9) on the concrete foundations (10), and detecting the integrity of all the armored connecting optical fibers (7) again;

step five: and backfilling the slotting position of the roadbed, and mechanically leveling to finish the laying of the grating array roadbed settlement monitoring sensing equipment.

Technical Field

The invention relates to the field of road health monitoring and protection, in particular to frozen soil roadbed deformation field optimization monitoring equipment and method based on a grating array.

Background

Under the dual background of human engineering activities and environmental climate warming, the frozen soil ground temperature in permafrost regions rises, the thickness of the active layer increases, the area of the frozen soil decreases, and further engineering disasters such as hot melt deformation increase year by year, particularly for highway engineering, the disturbance to the permafrost layer under a roadbed is more severe and roadbed diseases are more serious due to the strong heat absorption effect of black pavements. Deformation diseases of roads in permafrost regions are mainly caused by freeze-thaw changes of permafrost and mainly represented by large local deformation and deflection, rapid longitudinal form change, wide disease distribution range, the traditional monitoring method has the outstanding problems of no specific scheme, backward means, too late intervention time and the like, and the traditional point type monitoring sensing can only monitor part of key parts and cannot give consideration to other parts to be tested, so that the monitoring content cannot completely reflect the actual evolution process of the wide catastrophe distribution range of the roadbed and the development degree of the large catastrophe deformation.

Aiming at the problems, a regional, toughened and automatic disaster monitoring method design is developed around the key technology of frozen soil roadbed deformation field monitoring, the fiber-based optical fiber monitoring technology has the advantages of light weight, severe environment resistance, electromagnetic interference resistance and no need of electricity at a sensing point, a large-range, high-precision and high-toughness grating optical fiber array displacement sensor based on the Bragg grating optical fiber monitoring technology is designed, a sensor optimal arrangement method is provided according to a Kriging space interpolation method, the optimal sensor arrangement interval is determined, a long-term dynamic monitoring and interpretation method of the frozen soil roadbed deformation field is provided, and an automatic networking monitoring system of the frozen soil roadbed deformation field is provided.

At present, the traditional single-point monitoring technologies such as a single-point displacement meter and a fiber grating static level gauge are widely applied to roadbed settlement deformation monitoring, novel monitoring methods such as three-dimensional laser scanning and satellite radar interference technologies are gradually applied, the layout distance and the layout form of sensors are provided by point monitoring means according to engineering experience, roadbed field variables are difficult to monitor, the novel monitoring means are limited by cost, roadbed field variables are difficult to observe in a long-term mode, roadbed surface deformation monitoring can only be carried out, and the monitoring methods aiming at roadbed three-dimensional deformation fields are still in an exploration stage.

Disclosure of Invention

The invention aims to provide frozen soil roadbed deformation field optimization monitoring equipment and method based on a grating array, which are suitable for long-term stable monitoring of a frozen soil roadbed deformation field, form a high-precision and high-toughness grating optical fiber array sensor suitable for large deformation, form a sensing array networking automatic monitoring method and provide data support for stability and safety evaluation of the frozen soil roadbed.

The technical scheme adopted by the invention is as follows:

frozen soil roadbed deformation field optimization monitoring facilities based on grating array, its characterized in that:

the device comprises a high-pressure hydraulic pipe, a high-precision grating optical fiber pressure sensor, an armored connecting optical fiber, a reference sensor and an optical fiber demodulator;

the high-pressure hydraulic pipes are transversely embedded in a road bed and are arranged in sections, the high-precision grating optical fiber pressure sensor is arranged between the high-pressure hydraulic pipes of all the sections through a clamp type tee joint so that the high-pressure hydraulic pipes form a sealed pipe body, and anti-freezing liquid is filled in the high-pressure hydraulic pipes;

the reference sensor and the optical fiber demodulator are arranged on the outer side of a road bed, the reference sensor is arranged at the termination end of the high-pressure hydraulic pipe, and the high-precision grating optical fiber pressure sensor and the reference sensor are sequentially connected with each other through armored connection optical fibers and are connected into the optical fiber demodulator.

The initiating terminal of high pressure hydraulic pressure pipe is provided with the chock plug, and the benchmark sensor passes through the clamp formula tee bend and is connected with high pressure hydraulic pressure pipe at the termination end, and the clamp formula tee bend other end is provided with the chock plug.

The high-precision grating optical fiber pressure sensor, the high-pressure hydraulic pipe and the armored connecting optical fiber at the position of the high-precision grating optical fiber pressure sensor are packaged in the sedimentation box.

A semi-annular buckle used for fixing the high-precision grating optical fiber pressure sensor and the high-pressure hydraulic pipe is arranged in the sedimentation box, and small rollers are arranged on the upper side and the lower side of the high-pressure hydraulic pipe;

the two sides of the sedimentation box are provided with high-pressure hydraulic pipes and through holes for armored connecting optical fibers, and the sedimentation box is internally provided with ribs.

PVC pipes are arranged outside the high-pressure hydraulic pipes and the armored connecting optical fibers outside the sedimentation box, and redundant high-pressure hydraulic pipe coils are placed in the hydraulic pipe coil grooves.

The high-pressure hydraulic pipes are transversely arranged in the roadbed in multiple ways, and each high-pressure hydraulic pipe is connected to one termination end in a gathering mode and is provided with a reference sensor;

the high-precision grating optical fiber pressure sensors on the high-pressure hydraulic pipes are connected into the same optical fiber demodulator through the armored connecting optical fibers and the FC/APC joints.

The transverse arrangement distance of the high-precision grating optical fiber pressure sensor is 2m, and the longitudinal arrangement distance of the high-precision grating optical fiber pressure sensor is 4-6 m.

The reference sensor is arranged on the concrete foundation outside the road bed.

The frozen soil roadbed deformation field optimization monitoring method based on the grating array implemented by the equipment is characterized by comprising the following steps of:

the method comprises the following steps:

the method comprises the following steps: the starting end of a high-pressure hydraulic pipe in the equipment is sealed and plugged by a plug head, and after anti-freezing liquid is injected into the ending end, a pipe body is subjected to a pipe body pressure test and then sealed and plugged by the plug head;

step two: one end of the armored connecting optical fiber is connected into an optical fiber demodulator through an FC/APC (fiber channel/automatic control) connector, the initial wavelength value of the embedded grating optical fiber is measured, the liquid level pressure at the embedded position of the high-precision grating optical fiber pressure sensor is calculated, and then the liquid level difference of the position relative to the reference sensor is calculated, namely the relative settlement deformation of the roadbed at the moment;

step three: and extracting the settlement deformation value of each measuring point position, and performing ordinary Kriging spatial interpolation interpretation to form a roadbed settlement deformation field at the measured elevation position.

The equipment arrangement process is as follows:

the method comprises the following steps: after the road subgrade is constructed to the monitoring measurement elevation, the measurement is carried out along the cross section, and the specific position of the arrangement of the subgrade transverse and longitudinal grating array subgrade settlement monitoring sensing equipment is determined;

step two: excavating sensing equipment by a machine to lay ditch positions, wherein the excavation depth is 30cm, leveling the bottoms of the ditches, then filling 5cm of fine sand, and sequentially laying the sensing equipment of each transverse section;

step three: after the sensor equipment is laid, detecting the integrity of the armored connecting optical fiber to ensure that the sensors are all alive;

step four: collecting the armored connecting optical fibers and the high-pressure hydraulic pipes at node positions, arranging reference sensors at the node positions, pouring a concrete foundation at the natural ground position, fixing the reference sensors on the concrete foundation, and detecting the integrity of all the armored connecting optical fibers again;

step five: and backfilling the slotting position of the roadbed, and mechanically leveling to finish the laying of the grating array roadbed settlement monitoring sensing equipment.

The invention has the following advantages:

(1) the grating optical fiber array sensor provided by the invention can realize high-precision, large-range and high-durability settlement deformation monitoring, and the sensor component can adapt to large external deformation without damage, so that the uneven deformation field of the frozen soil roadbed can be effectively monitored.

(2) The method is based on a common Kriging space interpolation model to carry out sensor layout optimization and frozen soil roadbed deformation field monitoring, and can realize the frozen soil roadbed deformation field monitoring based on limited sensing layout when the monitoring cost is considered.

(3) The frozen soil roadbed deformation field monitoring method based on sensor optimized layout can provide a frozen soil roadbed deformation field interpretation method with reasonable prediction precision and prediction error.

(4) The integrated monitoring method of the sensing array constructed by the invention can realize expandable and reproducible sensing networking monitoring.

(5) The grating optical fiber array sensor networking monitoring system provided by the invention enriches frozen soil roadbed deformation field monitoring methods and roadbed defect detection methods.

(6) All the systems of the invention are convenient to install, simple to operate, small in equipment volume, easy to carry out work on engineering sites and can be mastered in a short time.

Drawings

FIG. 1 is a grating fiber displacement array sensing design;

FIG. 2 is a transverse arrangement scheme for monitoring a deformation field of a frozen soil roadbed;

FIG. 3 is a longitudinal arrangement scheme for monitoring a deformation field of a frozen soil roadbed;

FIG. 4 is a sectional view showing the internal structure of the settling box;

FIG. 5 is a sectional view showing the internal structure of a hydraulic tube plate;

FIG. 6 is a calculation result of optimized layout of the lateral sensors;

FIG. 7 shows the calculation results of the optimized layout of longitudinal sensors.

In the figure, 1-high pressure hydraulic pipe, 2-high precision grating optical fiber pressure sensor, 3-clamp type tee joint, 4-settling box, 5-PVC pipe, 6-hydraulic pipe coil groove, 7-armored connecting optical fiber, 8-plug, 9-reference sensor, 10-concrete foundation, 11-road subgrade, 12-natural ground, 13-optical fiber demodulator, 14-coil groove bottom high pressure hydraulic pipe, 15-coil groove top high pressure hydraulic pipe, 16-annular spring, 17-annular hoop, 18-limiting groove, 19-small roller, 20-semi-annular buckle, and 21-settling box internal ribbing.

Detailed Description

The present invention will be described in detail with reference to specific embodiments.

The invention relates to frozen soil roadbed deformation field optimization monitoring equipment based on a grating array, which comprises a high-pressure hydraulic pipe 1, a high-precision grating optical fiber pressure sensor 2, an armored connecting optical fiber 7, a reference sensor 9 and an optical fiber demodulator 13; the high-pressure hydraulic pipes 1 are transversely embedded in a road bed 11 and are arranged in sections, the high-precision grating optical fiber pressure sensors 2 are arranged among the high-pressure hydraulic pipes 1 of each section through the clamp type tee joints 3, so that the high-pressure hydraulic pipes 1 form sealed pipe bodies, and the high-pressure hydraulic pipes 1 are filled with anti-freezing liquid; the reference sensor 9 and the optical fiber demodulator 13 are arranged on the outer side of the road bed 11, the reference sensor 9 is arranged at the termination end of the high-pressure hydraulic pipe 1, and the high-precision grating optical fiber pressure sensor 2 and the reference sensor 9 are sequentially connected through the armored connection optical fiber 7 and are connected into the optical fiber demodulator 13.

The initiating terminal of high pressure hydraulic pressure pipe 1 is provided with chock plug 8, and reference sensor 9 is connected with high pressure hydraulic pressure pipe 1 at the termination end through clamp formula tee bend 3, and the clamp formula tee bend 3 other end is provided with chock plug 8.

The high-precision grating optical fiber pressure sensor 2, the high-pressure hydraulic pipe 1 at the position of the high-precision grating optical fiber pressure sensor and the armored connecting optical fiber 7 are packaged in the sedimentation box 4. A semi-annular buckle 10 for fixing the high-precision grating optical fiber pressure sensor 2 and the high-pressure hydraulic pipe 1 is arranged in the sedimentation box 4, and small rollers 19 are arranged on the upper side and the lower side of the high-pressure hydraulic pipe 1; the two sides of the sedimentation box 4 are provided with a high-pressure hydraulic pipe 1 and a perforation of an armored connecting optical fiber 7, and the sedimentation box 4 is internally provided with a sedimentation box internal ribbed 21.

PVC pipes 5 are arranged outside the high-pressure hydraulic pipes 1 and the armored connecting optical fibers 7 outside the sedimentation boxes 4, and redundant high-pressure hydraulic pipes 1 are placed in a hydraulic pipe coil groove 6 in a coiled mode.

The high-pressure hydraulic pipes 1 are transversely arranged in a roadbed in multiple ways, each high-pressure hydraulic pipe 1 is connected to a termination end in a gathering mode and is provided with a reference sensor 9; the high-precision grating optical fiber pressure sensors 2 on the high-pressure hydraulic pipes 1 are connected into the same optical fiber demodulator 13 through armored connecting optical fibers 7 and FC/APC joints. The high-precision grating optical fiber pressure sensor 2 is transversely arranged at a distance of 2m, and is longitudinally arranged at a distance of 4-6 m. The reference sensor 9 is arranged on a concrete foundation 10 outside a road bed 11.

The frozen soil roadbed deformation field optimization monitoring method based on the grating array implemented by the equipment comprises the following steps:

the method comprises the following steps: the starting end of a high-pressure hydraulic pipe 1 in the equipment is sealed and blocked by a plug 8, and after anti-freezing liquid is injected into the ending end, a pipe body is subjected to a pipe body pressure test and then sealed and blocked by the plug 8;

step two: one end of the armored connecting optical fiber 7 is connected into an optical fiber demodulator 13 through an FC/APC joint, the initial wavelength value of the embedded grating optical fiber is measured, the liquid level pressure of the embedded position of the high-precision grating optical fiber pressure sensor 2 is calculated, and then the liquid level difference of the position relative to a reference sensor 9 is calculated, namely the relative settlement deformation of the roadbed at the moment;

step three: and extracting the settlement deformation value of each measuring point position, and performing ordinary Kriging spatial interpolation interpretation to form a roadbed settlement deformation field at the measured elevation position.

Wherein, the arrangement process of the equipment is as follows:

the method comprises the following steps: after the road subgrade 11 is constructed to the monitoring measurement elevation, the measurement is carried out along the cross section, and the specific position of the arrangement of the subgrade transverse and longitudinal grating array subgrade settlement monitoring sensing equipment is determined;

step two: excavating sensing equipment by a machine to lay ditch positions, wherein the excavation depth is 30cm, leveling the bottoms of the ditches, then filling 5cm of fine sand, and sequentially laying the sensing equipment of each transverse section;

step three: after the sensor equipment is laid, detecting the integrity of the armored connecting optical fiber 7 to ensure that the sensors are all alive;

step four: summarizing the armored connecting optical fibers 7 and the high-pressure hydraulic pipes 1 at node positions, arranging reference sensors 9 at the node positions, pouring concrete foundations 10 at the positions of natural ground 12, fixing the reference sensors 9 on the concrete foundations 10, and detecting the integrity of all the armored connecting optical fibers 7 again;

step five: and backfilling the slotting position of the roadbed, and mechanically leveling to finish the laying of the grating array roadbed settlement monitoring sensing equipment.

The working mechanism of the invention is as follows:

the measuring and interpretation of the deformation field of the frozen soil roadbed are realized by utilizing a sensor consisting of a high-precision grating optical fiber pressure sensor and a high-pressure hydraulic pipe, namely, the liquid level pressure difference in the high-pressure hydraulic pipe is used as an indirect measuring variable, the high-precision grating optical fiber pressure sensor is packaged in a sedimentation box, when the soil body and the sedimentation box occur, the hydraulic pressure of the high-pressure hydraulic pipe at the position of the sedimentation box relatively changes, the change of the relative height difference is calculated back through the liquid level pressure difference between the position and a reference position, and the relative sedimentation deformation is obtained. The invention provides a high-precision optical grating optical fiber pressure sensor space optimization layout based on a Krigin space interpolation model, provides a frozen soil roadbed deformation field integrated monitoring layout principle with a transverse spacing L1 of 2m and a longitudinal spacing L2 of 4-6 m, can realize real-time monitoring and interpretation of a frozen soil roadbed deformation field with high precision, large range and large deformation in a reasonable prediction precision and limited cost range, improves the current situation of 'measurement without measurement and incomplete measurement' of the traditional frozen soil roadbed monitoring method, forms a frozen soil roadbed deformation field monitoring technology facing regionalization, toughness and automation, and provides an optical grating array type roadbed settlement monitoring sensing equipment system which is convenient to install, simple to operate, small in equipment volume, easy to carry out work in an engineering field and can be mastered in a short time.

The invention is described in further detail with reference to the accompanying drawings:

the apparatus comprises: the device comprises a 21mm high-pressure hydraulic pipe 1, a high-precision grating optical fiber pressure sensor 2, a clamp type tee joint 3, a 250mm multiplied by 50mm settling box 4, a 50mm PVC pipe 5, a hydraulic pipe coil groove 6 and an armored connecting optical fiber 7.

The 21mm high-pressure hydraulic pipe 1 is connected into a non-leakage whole section of pipe body through a plurality of clamp type tee joints 3 arranged at a fixed interval L1, the high-precision grating optical fiber pressure sensors 2 are arranged at the top end interfaces of the top clamp type tee joints 3, and the high-precision grating optical fiber pressure sensors 2 are connected through armored connecting optical fibers 7.

And reserving 21mm high-pressure hydraulic pipes 1 with enough redundant length between the clamp type tee joints 3, coiling the redundant 21mm high-pressure hydraulic pipes 1 into a hydraulic pipe coil groove 6, sleeving 50mm PVC pipes 5 outside the rest sections of 21mm high-pressure hydraulic pipes 1, packaging the high-precision grating optical fiber pressure sensor 2 into a 250mm multiplied by 50mm settlement box 4, repeating the process, and assembling to form the grating array type roadbed settlement monitoring sensing equipment.

When in monitoring:

the method comprises the steps of constructing a road subgrade 11 to a monitoring measurement elevation, then carrying out paying-off measurement along a cross section, determining the specific arrangement position of subgrade transverse and longitudinal grating array subgrade settlement monitoring sensing equipment, excavating a sensing equipment arrangement groove position through machinery, wherein the excavation depth is 30cm, leveling the bottom of a groove, filling 5cm of fine sand, sequentially arranging sensing equipment of each transverse cross section, detecting the integrity degree of an armored connecting optical fiber 7 after the arrangement of the sensing equipment is completed, ensuring that the sensors are all alive, summarizing the armored connecting optical fibers 7 and a 21mm high-pressure hydraulic pipe 1 to a node position, arranging a reference sensor 9 at the node position, pouring a concrete foundation 10 at a natural ground 12 position, fixing the reference sensor 9 on the concrete foundation 10, and detecting the integrity degree of all the armored connecting optical fibers 7 again. And finally, backfilling the slotting position of the roadbed, and mechanically leveling to finish the laying of the grating array roadbed settlement monitoring sensing equipment.

The method comprises the steps of sealing and plugging a starting end of a 21mm high-pressure hydraulic pipe 1 in the grating array type roadbed settlement monitoring sensing equipment by using a plug 8, injecting an antifreezing solution into a stopping end of the 21mm high-pressure hydraulic pipe 1, performing a pipe body pressure test, and sealing and plugging by using the plug 8. One end of the armored connecting optical fiber 7 is connected into an optical fiber demodulator 13 through an FC/APC joint, the initial wavelength value of the embedded grating optical fiber is measured, the liquid level pressure of the embedded position of the high-precision grating optical fiber pressure sensor 2 is calculated, and then the liquid level difference of the position relative to the reference sensor 9 is calculated, namely the relative settlement deformation of the roadbed at the moment. And extracting the settlement deformation value of each measuring point position, and performing ordinary Kriging spatial interpolation interpretation to form a roadbed settlement deformation field at the measured elevation position.

The equipment of the invention can be divided into the following two systems:

1. grating array type roadbed settlement monitoring sensing equipment system

The grating array type roadbed settlement monitoring sensing equipment consists of a 21mm high-pressure hydraulic pipe, a high-precision grating optical fiber pressure sensor, a clamp type tee joint, a 250mm multiplied by 50mm settlement box, a 50mm PVC pipe, a hydraulic pipe coil groove and an armored connection optical fiber.

Determining the layout elevation of the grating array type roadbed settlement monitoring sensing equipment according to the structural form of the frozen soil roadbed, performing common Kriging space interpolation optimization analysis on the transverse layout spacing and the longitudinal layout spacing of the sensors, taking the minimum estimation mean square error and the average prediction accuracy as the evaluation criteria of deformation field prediction, and determining the optimal sensor layout parameters by combining with monitoring cost measurement and calculation. The correlation calculation results are shown in the attached figures 6-7, and the transverse arrangement distance is recommended to be 2m, and the longitudinal arrangement distance is recommended to be 4-6 m. Taking a roadbed monitoring field with the road width of 7m and the longitudinal length of 100m as an example, 68-104 grating array sensors are distributed in total.

And (3) taking the transverse spacing L1 to be 2m, determining the arrangement number of the high-precision grating optical fiber pressure sensors in the transverse section according to the width of the roadbed to be measured, wherein the design measurement range of the high-precision grating optical fiber pressure sensors is 0-50 kPa, the measurement precision is +/-0.5% F.S., and the measurement resolution is less than 0.02% F.S. Each pressure sensor is connected to a 21mm high-pressure hydraulic pipe through a clamp type tee joint, the 21mm high-pressure hydraulic pipe with the length of 2m is reserved between the clamp type tee joints, namely 2m relative settlement can be generated between adjacent sensors, a 21mm high-pressure hydraulic pipe disc with the redundant length is placed in a hydraulic pipe disc groove, each pressure sensor is connected with optical fibers in series through armor to form an array, each pressure sensor is packaged in a 250mm multiplied by 50mm settlement box, and grating roadbed array settlement monitoring sensing equipment is formed through assembly.

And taking the longitudinal distance L2 to be 4-6 m, sequentially completing the layout of each cross-section grating array type roadbed settlement monitoring sensing equipment, gathering the loop sensing equipment, then accessing the collected loop sensing equipment into a set reference sensor, and accessing the reference sensor into a data acquisition system for testing.

2. Data acquisition and deformation field interpretation system

The wavelength range of the fiber grating demodulator is 1527-1568 nm, the wavelength resolution is 1pm, the dynamic range is 45dB, and the demodulator is connected with the grating array type roadbed settlement monitoring sensing equipment through an FC/APC connector.

And measuring an initial wavelength value after the sensor is buried, subsequently monitoring to obtain the measured wavelength value, calculating the liquid level pressure of each measuring point position, and calculating the hydraulic pressure difference of the position relative to the reference sensing position, namely the relative settlement deformation of the roadbed of the measuring point at the moment. And repeating the calculation process to calculate the relative settlement deformation at each position in the monitoring field.

The liquid level pressure calculation process is as follows:

dλ_B＝(1-P_e)λ_BP/E (1)

in the formula, λ_bIs the center wavelength, n, of the grating fiber_effIs the finite refractive index of the fiber core, E is the Young's modulus of the fiber grating pressure sensing probe, P_eIs the effective elastic-optical coefficient of the optical fiber material, v is the Poisson's ratio, P of the optical fiber material₁₁And P₁₂The anisotropy of the optical fiber material is shown, and P is the test pressure.

The relative sedimentation deformation value is calculated as follows:

wherein, the delta H is the liquid level difference between the reference measuring point A and any measuring point B_A、μ_BRespectively, the liquid level test pressure, gamma, at point A, B_wThe volume weight of the antifreeze solution (the freezing point is 10.92kN/m at 60℃)³)。

The calculation and interpretation method of the subgrade settlement deformation field comprises the following steps:

and extracting the settlement deformation value of each measuring point position for ordinary Kriging space interpolation interpretation, wherein the calculation process is expressed as:

in the formula, z (x)₀) For subgrade settlement variable at x₀M is the expected value of the subgrade settlement variable in the search neighborhood, z (x)_i) For finding the true value, lambda, of the subgrade settlement variable in the neighborhood_iTo search for weights in the neighborhood, m (x)_i) The expected value is re-estimated at each evaluation location.

Selecting lambda with unbiased property and minimum estimation variance_iI.e. λ when the following condition is satisfied_iOptimally:

in the formula, E2]Shows that the expected value of the variable of the subgrade settlement, Var [ deg. ], is obtained]And the variable variance of the subgrade settlement is obtained. Solving equation (5) for the weighting factor λ_iThe minimum estimation variance of the roadbed settlement variable interpolation is obtained, the roadbed settlement variable value of an unknown point is predicted according to the formula (4), and the variable value of the roadbed settlement deformation field area is obtained through interpretation.

The invention is not limited to the examples, and any equivalent changes to the technical solution of the invention by a person skilled in the art after reading the description of the invention are covered by the claims of the invention.