Sea area steel sheet pile cofferdam construction monitoring method and system based on optical fiber sensing

Abstract

The present application relates to the technical field of marine cofferdam structure monitoring and discloses a marine steel sheet pile cofferdam construction monitoring method and system based on optical fiber sensing. The method comprises: installing a protective sleeve inside the steel sheet pile and driving the steel sheet pile into the sea to form a marine steel sheet pile cofferdam structure; placing a prepared inclinometer tube in the protective sleeve and securing it; connecting one end of the optical fiber in the inclinometer tube to the pump light source interface of an analyzer, and connecting the other end of the optical fiber in the inclinometer tube to the continuous wave detection light source interface of the analyzer; the analyzer collects pump light data and detection light data while transmitting pulsed pump light to one end of the optical fiber and continuous detection light to the other end of the optical fiber, and obtains real-time monitoring results of the deformation of the marine steel sheet pile cofferdam structure based on the pump light data and detection light data. The present application can improve the measurement accuracy of steel sheet pile deformation monitoring in marine environments.

Description

Technical Field

[0001] The present application relates to the technical field of sea area cofferdam structure monitoring, and in particular to a sea area steel sheet pile cofferdam construction monitoring method and monitoring system based on optical fiber sensing. Background Art

[0002] Double-layer steel sheet pile cofferdams are temporary water retaining structures used in infrastructure projects such as water conservancy projects, bridges, tunnels, and marine projects. They create a dry construction site within aquatic environments, meeting the basic requirements of building structures in the ocean. During construction, assessing the stability of the steel sheet piles is crucial, requiring deformation monitoring to obtain information. Traditional measurement methods utilize a PVC (polyvinyl chloride) inclinometer tube. An inclinometer probe slowly descends through the tube to the bottom of the hole. After a period of constant temperature, displacement is measured from bottom to top. Tilt values ​​are measured at each depth point in each hole twice, and the average value is used as the raw offset. An inclinometer probe typically consists of a housing, sensor, circuitry, battery, and data transmission module. The sensor is a key component of the probe, and commonly used sensors include accelerometers and gyroscopes, which detect changes in the inclination of the inclinometer tube. The accelerometer-based inclinometer probe uses the direction of acceleration in the gravitational field to determine the tilt angle. When the probe is in a tilted state, the accelerometer will sense the components of gravity acceleration in different directions. By measuring the magnitude and direction of these components, the tilt angle of the probe relative to the plumb line can be calculated.

[0003] However, existing technologies struggle to maintain measurement accuracy in humid and corrosive marine environments, and the use of waterproof or anti-corrosion coatings or protective covers can affect measurement results. This method also suffers from slow monitoring speeds, discrete measurements, and the uneconomical nature of array monitoring for large-scale, deep-layer soil deformation.

[0004] Therefore, the existing technology still needs to be improved and developed. Summary of the Invention

[0005] The main purpose of this application is to provide a method and system for monitoring the construction of sea steel sheet pile cofferdams based on optical fiber sensing, aiming to solve the problem in the prior art that sea steel sheet pile deformation monitoring uses PVC inclinometer tubes, resulting in low measurement accuracy when used in a sea environment and inability to achieve real-time, all-weather monitoring.

[0006] According to a first aspect of an embodiment of the present application, there is provided a method for monitoring the construction of sea steel sheet pile cofferdams based on optical fiber sensing, the method comprising the following steps: installing a protective sleeve on the inner side of a steel sheet pile, and driving the steel sheet pile into the sea to form a sea steel sheet pile cofferdam structure; placing a prepared inclinometer tube in the protective sleeve for fixing; connecting one end of the optical fiber in the inclinometer tube to a pump light source interface of an analyzer, and connecting the other end of the optical fiber in the inclinometer tube to a continuous wave detection light source interface of an analyzer; the analyzer collects pump light data of the pulsed pump light and detection light data of the continuous detection light when transmitting pulsed pump light to one end of the optical fiber and transmitting continuous detection light to the other end of the optical fiber, and obtains monitoring results of the deformation of the sea steel sheet pile cofferdam structure based on the pump light data and the detection light data.

[0007] Optionally, in one embodiment of the present application, the protective sleeve is a galvanized steel pipe; the installation of the protective sleeve on the inner side of the steel sheet pile is specifically: welding a galvanized steel pipe on the inner side of the steel sheet pile, wherein the diameter of the galvanized steel pipe is larger than the diameter of the inclinometer tube, and the diameter difference between the galvanized steel pipe and the inclinometer tube is within a set range.

[0008] Optionally, in one embodiment of the present application, the prepared inclinometer tube is placed in the protective sleeve for fixing, which specifically includes: structurally modifying the original inclinometer tube, and installing at least one optical fiber in the modified inclinometer tube to obtain the prepared inclinometer tube; placing the inclinometer tube installed with the optical fiber into the galvanized steel pipe, and filling sand into the gap between the inclinometer tube and the galvanized steel pipe to fix it.

[0009] Optionally, in one embodiment of the present application, a first optical fiber and a second optical fiber are installed in the inclinometer tube; the structural modification of the original inclinometer tube and the installation of at least one optical fiber in the modified inclinometer tube to obtain the prepared inclinometer tube specifically include: providing a first guide groove, a second guide groove, a third guide groove, and a fourth guide groove on the inner wall of the original inclinometer tube, wherein the first guide groove and the second guide groove are symmetrically arranged, and the third guide groove and the fourth guide groove are symmetrically arranged; installing the first optical fiber along the first guide groove and the second guide groove using an adhesive so that one end and the other end of the first optical fiber extend out of the inclinometer tube, and installing the second optical fiber along the third guide groove and the fourth guide groove using an adhesive so that one end and the other end of the second optical fiber extend out of the inclinometer tube.

[0010] Optionally, in one embodiment of the present application, the method of using an adhesive to install the first optical fiber along the first guide groove and the second guide groove so that one end and the other end of the first optical fiber extend out of the inclinometer tube, and using an adhesive to install the second optical fiber along the third guide groove and the fourth guide groove so that one end and the other end of the second optical fiber extend out of the inclinometer tube specifically includes: winding the middle section of the first optical fiber around the bottom end of the inclinometer tube, using an adhesive to stick the first section of the first optical fiber in the first guide groove so that the first guide groove is completely covered vertically by the first section of the first optical fiber, and using an adhesive to stick the tail section of the first optical fiber in the second guide groove The second guide groove is completely covered by the tail section of the second optical fiber in the vertical direction, the middle section of the second optical fiber is wound around the bottom end of the inclinometer tube, the first section of the second optical fiber is pasted in the third guide groove with an adhesive, so that the first guide groove is completely covered by the first section of the second optical fiber in the vertical direction, and the tail section of the second optical fiber is pasted in the fourth guide groove with an adhesive, so that the fourth guide groove is completely covered by the tail section of the second optical fiber in the vertical direction; wherein, one end of the first optical fiber extends out of the first guide groove, the other end of the first optical fiber extends out of the second guide groove, one end of the second optical fiber extends out of the third guide groove, and the other end of the second optical fiber extends out of the fourth guide groove.

[0011] Optionally, in one embodiment of the present application, the original inclinometer tube is structurally modified, and at least one optical fiber is installed in the modified inclinometer tube to obtain a prepared inclinometer tube, which then further includes: installing a detachable protective cover at the upper end of the inclinometer tube and installing a sealed protective cover at the lower end of the inclinometer tube.

[0012] Optionally, in one embodiment of the present application, the monitoring result of the deformation of the sea area steel sheet pile cofferdam structure is obtained based on the pump light data and the detection light data, specifically including: calculating the frequency difference between the pulsed pump light and the continuous detection light based on the pump light data and the detection light data, and obtaining Brillouin frequency shift data based on the frequency difference; obtaining the strain data of the sea area steel sheet pile cofferdam structure based on the Brillouin frequency shift data; and obtaining the monitoring result of the deformation of the sea area steel sheet pile cofferdam structure based on the strain data.

[0013] A second aspect of an embodiment of the present application further provides a marine steel sheet pile cofferdam structure deformation monitoring system, wherein the marine steel sheet pile cofferdam structure deformation monitoring system comprises a protective sleeve, an inclinometer tube, and an analyzer, wherein the protective sleeve is used to be installed on the marine steel sheet pile, the inclinometer tube is sleeved in the protective sleeve, and at least one optical fiber is connected to the inclinometer tube, one end of the optical fiber is connected to the pump light source interface of the analyzer, and the other end of the optical fiber is connected to the continuous wave detection light source interface of the analyzer;

[0014] The analyzer is used to collect pump light data of the pulsed pump light and detection light data of the continuous detection light when transmitting pulsed pump light to one end of the optical fiber and transmitting continuous detection light to the other end of the optical fiber, and obtain monitoring results of the deformation of the steel sheet pile cofferdam structure in the sea area based on the pump light data and the detection light data.

[0015] Optionally, in one embodiment of the present application, the protective sleeve is a galvanized steel pipe, the diameter of the galvanized steel pipe is larger than the diameter of the inclinometer tube, the diameter difference between the galvanized steel pipe and the inclinometer tube is within a set range, and sand is filled between the galvanized steel pipe and the inclinometer tube.

[0016] Optionally, in one embodiment of the present application, a first optical fiber and a second optical fiber are installed in the inclinometer tube, and a first guide groove, a second guide groove, a third guide groove and a fourth guide groove are provided in the inclinometer tube, the first guide groove and the second guide groove are symmetrically arranged, and the third guide groove and the fourth guide groove are symmetrically arranged; the first section of the first optical fiber is installed in the first guide groove through an adhesive layer, the tail section of the first optical fiber is installed in the second guide groove through an adhesive layer, the first section of the second optical fiber is installed in the third guide groove through an adhesive layer, and the tail section of the second optical fiber is installed in the fourth guide groove through an adhesive layer, one end of the first optical fiber extends out of the first guide groove, and the other end of the first optical fiber extends out of the second guide groove, one end of the second optical fiber extends out of the third guide groove, and the other end of the second optical fiber extends out of the fourth guide groove.

[0017] Beneficial effect: The present application provides a method and system for monitoring the construction of sea steel sheet pile cofferdams based on fiber optic sensing. The present application first installs a protective casing and steel sheet piles to reserve an area for placing an inclinometer tube, then drives the steel sheet piles into the sea to form a sea steel sheet pile cofferdam structure, and then places the inclinometer tube into the protective casing and fixes it to prevent the construction process of driving the steel sheet piles into the sea from affecting the inclinometer tube structure, thereby improving the accuracy of subsequent monitoring results. When structural monitoring is required, pulse light is injected into one end of the optical fiber of the inclinometer tube and continuous light is injected into the other end of the optical fiber through an analyzer to measure the monitoring results of the deformation of the sea steel sheet pile cofferdam structure, thereby improving the measurement accuracy of steel sheet pile deformation monitoring in a marine environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments recorded in this application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0019] Figure 1This is a top view of a preferred embodiment of the marine steel sheet pile cofferdam structure deformation monitoring system of the present application;

[0020] Figure 2 This is a cross-sectional view from the front of a preferred embodiment of the sea area steel sheet pile cofferdam structure deformation monitoring system of the present application;

[0021] Figure 3 This is a cross-sectional view of an inclinometer tube in a preferred embodiment of the marine steel sheet pile cofferdam structure deformation monitoring system of the present application;

[0022] Figure 4 It is a flow chart of a preferred embodiment of the method for monitoring sea steel sheet pile cofferdam construction based on optical fiber sensing in this application.

[0023] Description of reference numerals:

[0024] 100, steel sheet pile; 210, galvanized steel pipe; 220, inclinometer tube; 221, first guide groove; 222, second guide groove; 223, third guide groove; 224, fourth guide groove; 225, first optical fiber; 226, second optical fiber; 300, analyzer; 301, pump light source interface; 302, continuous wave detection light source interface. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solutions and effects of this application clearer and more specific, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. The described embodiments are only possible technical implementations of this application and are not all possible implementations. Based on the embodiments in this application, those skilled in the art can fully combine the embodiments of this application to obtain other embodiments without creative work, and these embodiments are also within the scope of protection of this application.

[0026] First, the nouns involved in the embodiments of this application are introduced:

[0027] BOTDA, Brillouin Optical Time Domain Analysis, Brillouin optical time domain analysis technology;

[0028] SBS, Stimulated Brillouin Scattering, stimulated Brillouin scattering.

[0029] To address the problem of low measurement accuracy when using PVC inclinometer tubes for deformation monitoring of steel sheet piles in offshore environments, this application first installs a protective sleeve and steel sheet piles to reserve an area for the inclinometer tube, then drives the steel sheet piles into the sea to form a steel sheet pile cofferdam structure in the offshore area. The inclinometer tube is then placed in the protective sleeve and fixed to prevent the construction process of the steel sheet piles being driven into the sea from affecting the inclinometer tube structure, thereby improving the accuracy of subsequent monitoring results. When structural monitoring is required, the analyzer injects pulsed light into one set of optical fibers connected to the inclinometer tube and continuous light into the other set of optical fibers, thereby measuring the deformation monitoring results of the steel sheet pile cofferdam structure in the offshore area, thereby improving the measurement accuracy of steel sheet pile deformation monitoring in the offshore environment. This application improves corrosion resistance and measurement accuracy through optical fiber sensing, replacing discrete monitoring to achieve continuous, real-time, full-section deformation monitoring; automated data acquisition shortens the monitoring cycle, distributed monitoring reduces the number of sensors, and reduces the cost of large-scale deep deformation monitoring; and high-precision strain data is used to provide early warning of steel sheet pile instability risks, providing real-time basis for construction decisions.

[0030] This application can improve the monitoring accuracy of the deformation of steel sheet pile cofferdam structures in the sea area. The fiber optic sensing has a high resolution, which is far superior to the 0.5-meter interval discrete measurement of traditional inclinometers. This application is environmentally adaptable, and the inclinometer tube and optical fiber are integrated into a design to adapt to harsh conditions such as high pressure, corrosion, and sediment scouring in seawater.

[0031] The following specific embodiments are used to describe the technical solution of the present application in detail. The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described in detail in some embodiments.

[0032] like Figure 1 、 Figure 2 and Figure 3 As shown, an embodiment of the present application provides a marine steel sheet pile cofferdam structure deformation monitoring system, wherein the marine steel sheet pile cofferdam structure deformation monitoring system is constructed according to a marine steel sheet pile cofferdam construction monitoring method based on optical fiber sensing;

[0033] The marine steel sheet pile 100 cofferdam structure deformation monitoring system includes a protective sleeve, an inclinometer tube 220, and an analyzer 300. The protective sleeve is used to be installed on the marine steel sheet pile 100. The inclinometer tube 220 is sleeved in the protective sleeve. At least one optical fiber is connected to the inclinometer tube 220. One end a of the optical fiber is connected to the pump light source interface 301 of the analyzer, and the other end b of the optical fiber is connected to the continuous wave detection light source interface 302 of the analyzer.

[0034] The analyzer is used to collect pump light data of the pulsed pump light and detection light data of the continuous detection light when transmitting pulsed pump light to one end a of the optical fiber and transmitting continuous detection light to the other end b of the optical fiber, and obtain the monitoring results of the deformation of the sea area steel sheet pile 100 cofferdam structure based on the pump light data and the detection light data.

[0035] In one embodiment of the present application, the protective sleeve is a galvanized steel pipe 210, the diameter of the galvanized steel pipe 210 is larger than the diameter of the inclinometer tube 220, the diameter difference between the galvanized steel pipe 210 and the inclinometer tube 220 is within a set range, and sand is filled between the galvanized steel pipe 210 and the inclinometer tube 220.

[0036] In one embodiment of the present application, Figure 3 As shown, a first optical fiber 225 and a second optical fiber 226 are installed in the inclinometer tube 220. A first guide groove 221, a second guide groove 222, a third guide groove 223 and a fourth guide groove 224 are provided in the inclinometer tube 220. The first guide groove 221 and the second guide groove 222 are symmetrically arranged, and the third guide groove 223 and the fourth guide groove 224 are symmetrically arranged. The first section of the first optical fiber 225 is installed in the first guide groove 221 through an epoxy resin adhesive layer, and the tail section of the first optical fiber 225 is installed in the first guide groove 221 through an epoxy resin adhesive layer. In the second guide groove 222, the first section of the second optical fiber 226 is installed in the third guide groove 223 through an epoxy resin adhesive layer, and the tail section of the second optical fiber 226 is installed in the fourth guide groove 224 through an epoxy resin adhesive layer. One end a of the first optical fiber 225 extends out of the first guide groove 221, and the other end b of the first optical fiber 225 extends out of the second guide groove 222. One end of the second optical fiber 226 extends out of the third guide groove 223, and the other end of the second optical fiber 226 extends out of the fourth guide groove 224.

[0037] Specifically, the galvanized steel pipe 210 is welded to the inside of the steel sheet pile 100. A first guide groove 221, a second guide groove 222, a third guide groove 223, and a fourth guide groove 224 are provided within the inclinometer tube 220. The first guide groove 221 is symmetrically arranged with the second guide groove 222, and the third guide groove 223 is symmetrically arranged with the fourth guide groove 224. Two optical fibers are arranged in two groups: a first optical fiber 225 in one group and a second optical fiber 226 in the other. The first optical fiber 225 and the second optical fiber 226 are arranged adjacent to each other. Because the galvanized steel pipe 210 has a larger diameter than the inclinometer tube 220, the inclinometer tube 220 can be easily placed within the galvanized steel pipe 210. A viscous structure (such as sand) is provided in the gap between the inclinometer tube 220 and the galvanized steel pipe 210 to secure the tube.

[0038] It should be noted that the first guide groove 221, the second guide groove 222, the third guide groove 223 and the fourth guide groove 224 are provided in the inclinometer tube 220. The grooves may be directly cut in the tube wall of the inclinometer tube 220, or a pipe fitting having the first guide groove 221, the second guide groove 222, the third guide groove 223 and the fourth guide groove 224 is sleeved on the inner wall of the inclinometer tube 220.

[0039] The BOTDA mainframe consists of a pump light source, a continuous-wave probe light source, and a corresponding fiber-optic sensing network. The pump light source's modulation frequency matches the fiber's scattered frequency shift. The single-mode fiber is longer than the inclinometer tube 220, ensuring full coverage from end to end. During installation, adhesive is applied along the entire length of the fiber to ensure a perfect fit between the fiber-optic sensing cable and the grooves in the inner wall of the inclinometer tube 220. Accurate deformation monitoring data is generated by collecting and analyzing scattered light generated by the interaction of pump and probe light within the fiber.

[0040] The method for monitoring the construction of sea steel sheet pile cofferdams based on optical fiber sensing described in the preferred embodiment of this application is as follows: Figure 4 As shown, the method for monitoring sea area steel sheet pile cofferdam construction based on optical fiber sensing includes the following steps:

[0041] In step S101, a protective casing is installed inside the steel sheet pile, and the steel sheet pile is driven into the sea to form a sea area steel sheet pile cofferdam structure.

[0042] In one possible implementation, the protective sleeve is a galvanized steel pipe welded inside the steel sheet pile, wherein the diameter of the galvanized steel pipe is larger than the diameter of the inclinometer tube, and the diameter difference between the galvanized steel pipe and the inclinometer tube is within a set range.

[0043] Specifically, a galvanized steel pipe with a diameter slightly larger than the inclinometer pipe is welded and fixed on the inner side of the steel sheet pile web, and then the steel sheet piles are driven into the sea to construct a double-layer steel sheet pile cofferdam.

[0044] Furthermore, during the welding and securing process, galvanized steel pipes (thin-walled galvanized steel pipes) are welded to the inside of the steel sheet pile web. This provides an external protective sheath for the inclinometer tube and prevents interference with the sheet pile's inherent structural strength. The inner diameter of the galvanized steel pipe is slightly larger than the outer diameter of the inclinometer tube (for example, if the inclinometer tube has a 70mm outer diameter, the inner diameter of the galvanized steel pipe can be 75mm), ensuring smooth insertion. A continuous weld seam is used, with a weld height of at least 80% of the steel pipe wall thickness, to ensure resistance to peeling during long-term use in seawater. After welding, the weld area is secondary galvanized or coated with epoxy resin to prevent seawater corrosion.

[0045] It should be understood that in this embodiment, the elevation of the bagged sand counter-pressure slope is zero, the double-row steel sheet pile cofferdam body elevation is +3m (3m above the plane of the bagged sand counter-pressure slope), the crest elevation is +6m, and the weir width is 10m. The steel sheet piles are 30-33m long, connected by steel tie rods between the inner and outer rows. An L-shaped buttress retaining wall is installed at the crest of the weir, and the weir body is backfilled with medium-coarse sand. The cofferdam area 8m below sea level is backfilled with medium-coarse sand, and localized weak soil layers within the weir body are reinforced with jet grouting piles. The outer riprap fill is 10m wide and has a top elevation of -2.0m (2m below the plane of the bagged sand counter-pressure slope). From bottom to top, the fill consists of 50cm thick 20-80mm graded crushed stone, 50cm thick second-layer stone, and 500-600kg rubble. The fill has a 1:3 side slope and connects smoothly with the riprap footing. The riprap footing is made of 60-200kg boulders. The inner side of the cofferdam is back-pressured with film-bag sand and the surface is protected with film-bag concrete.

[0046] In step S102, the prepared inclinometer casing is placed in the protective casing and fixed.

[0047] In one possible implementation, the original inclinometer tube is structurally modified, and at least one optical fiber is installed in the modified inclinometer tube to obtain a prepared inclinometer tube; the inclinometer tube installed with the optical fiber is placed in the galvanized steel pipe, and the gap between the inclinometer tube and the galvanized steel pipe is filled with sand to fix it.

[0048] Specifically, an inclinometer tube with an optical fiber attached is buried in a galvanized steel pipe, and the gap between the inclinometer tube and the galvanized steel pipe is filled with sand.

[0049] Next, an inclinometer tube with optical fiber attached is placed inside a galvanized steel pipe, and the gaps are filled with medium-coarse sand. During the installation process, steel sheet piles welded to the galvanized steel pipe are driven into the seabed using a vibratory or hydraulic hammer, maintaining verticality deviation within a specified percentage. The cofferdam structure is assembled, with the inner and outer rows of steel sheet piles connected by steel tie rods to form a double-layer cofferdam structure with a crest elevation of +6 meters and a width of 10 meters.

[0050] In one possible implementation, a first optical fiber and a second optical fiber are installed in the inclinometer tube. A first guide groove, a second guide groove, a third guide groove, and a fourth guide groove are defined on the inner wall of the original inclinometer tube, wherein the first guide groove is symmetrically arranged with the second guide groove, and the third guide groove is symmetrically arranged with the fourth guide groove. The first optical fiber is installed along the first and second guide grooves using an adhesive, such that one end and the other end of the first optical fiber extend out of the inclinometer tube. The second optical fiber is also installed along the third and fourth guide grooves using an adhesive, such that one end and the other end of the second optical fiber extend out of the inclinometer tube.

[0051] Specifically, two groups of symmetrical slots are opened on the inner wall of the inclinometer tube, and the optical fibers are tightly fitted into the slots on the inner wall of the inclinometer tube.

[0052] Furthermore, during the installation of the inclinometer tube and one end of the optical fiber and the other end of the optical fiber, two sets of symmetrical grooves are processed on the inner wall of the inclinometer tube. The groove depth is slightly larger than the optical fiber diameter (such as 0.3mm) to ensure that the optical fiber fits tightly; the single-mode optical fiber is pasted along the groove of the inclinometer tube by applying adhesive along the entire length and fixed with adhesive to ensure that the optical fiber path is consistent with the axial direction of the inclinometer tube; the length of the optical fiber must be greater than the length of the inclinometer tube (for example, if the inclinometer tube is 30m long, the optical fiber can be selected to be 65m) to achieve full coverage.

[0053] In one possible implementation, the middle section of the first optical fiber is wound around the bottom end of the inclinometer tube, the first section of the first optical fiber is adhered to the first guide groove using epoxy resin adhesive, so that the first guide groove is completely vertically covered by the first section of the first optical fiber, and the tail section of the first optical fiber is adhered to the second guide groove using epoxy resin adhesive, so that the second guide groove is completely vertically covered by the tail section of the second optical fiber. The middle section of the second optical fiber is wound around the bottom end of the inclinometer tube, the first section of the second optical fiber is adhered to the third guide groove using epoxy resin adhesive, so that the first guide groove is completely vertically covered by the first section of the second optical fiber, and the tail section of the second optical fiber is adhered to the fourth guide groove using adhesive, so that the fourth guide groove is completely vertically covered by the tail section of the second optical fiber. One end of the first optical fiber extends out of the first guide groove, the other end of the first optical fiber extends out of the second guide groove, one end of the second optical fiber extends out of the third guide groove, and the other end of the second optical fiber extends out of the fourth guide groove.

[0054] Specifically, a specific section of fiber optic cable is wrapped around the bottom end of the inclinometer casing. The fiber is then attached along the notches in the casing's inner wall and secured with adhesive to ensure stability and accurate positioning within the casing. The inclinometer casing, with the attached fiber, is then placed into the aforementioned galvanized steel pipe, and the space between the steel pipe and the inclinometer casing is filled with sand. Once all installation is complete, the fiber optic sensing system can begin automatic monitoring.

[0055] In a possible implementation, a detachable protective cover is installed at the upper end of the inclinometer tube, and a sealing protective cover is installed at the lower end of the inclinometer tube.

[0056] Specifically, the inclinometer tube has an outer diameter of 70 mm and two symmetrical notches on its inner wall. These notches are precisely cut during production, with a depth slightly greater than the diameter of the fiber optic sensing cable to ensure a tight fit. The length can be increased based on site requirements. To prevent debris like mud and sand from entering and clogging the inclinometer tube, protective caps must be installed at both ends. The upper cap is designed to facilitate testing, while the lower cap is sealed with a special glue to prevent mud and sand from entering and ensure test accuracy.

[0057] In step S103, one end of the optical fiber in the inclinometer tube is connected to the pump light source interface of the analyzer, and the other end of the optical fiber in the inclinometer tube is connected to the continuous wave detection light source interface of the analyzer.

[0058] Specifically, one end of the optical fiber is connected to the BOTDA host pump light source interface and the other end is connected to the continuous wave detection light source interface.

[0059] In step S104, the analyzer collects pump light data of the pulsed pump light and detection light data of the continuous detection light when transmitting pulsed pump light to one end of the optical fiber and transmitting continuous detection light to the other end of the optical fiber, and obtains the monitoring results of the deformation of the steel sheet pile cofferdam structure in the sea area based on the pump light data and the detection light data.

[0060] In one possible implementation, based on the pump light data and the detection light data, the frequency difference between the pulsed pump light and the continuous detection light is calculated, and Brillouin frequency shift data is obtained based on the frequency difference; based on the Brillouin frequency shift data, the strain data of the sea area steel sheet pile cofferdam structure is obtained; and based on the strain data, the monitoring results of the deformation of the sea area steel sheet pile cofferdam structure are obtained.

[0061] Specifically, the deformation data of the steel sheet piles is obtained and uploaded through automatic monitoring by the instrument.

[0062] It is understood that the analyzer is a BOTDA host, or Brillouin Optical Time Domain Analyzer. The BOTDA host transmits pulsed pump light and continuous probe light, and detects the Brillouin scattered signal generated in the optical fiber to invert the Brillouin frequency shift at each point in the fiber, thereby achieving distributed monitoring of strain or temperature.

[0063] Specifically, high-frequency pulsed light (pump light) and low-frequency continuous light (probe light) are injected into both ends of the optical fiber respectively. The pump light is a pulse signal and the probe light is a continuous wave signal. When the frequency difference between the two beams of light meets certain conditions, stimulated Brillouin scattering will occur, and energy will be transferred from the pump light to the probe light. By detecting the power change of the probe light at each position of the optical fiber, the Brillouin gain at that position can be obtained. By scanning the frequency difference between the pump light and the probe light, the Brillouin gain spectrum at each position of the optical fiber can be reconstructed. The Brillouin frequency shift at each position of the optical fiber can then be obtained by fitting, ultimately realizing distributed strain sensing.

[0064] Furthermore, one end of the optical fiber is connected to the pump light source (short pulse light) of the BOTDA mainframe, and the other end is connected to a continuous-wave probe light source. Brillouin scattering excitation: As the pump light pulse propagates along the fiber, it stimulates Brillouin scattering with the probe light, generating a frequency shift signal related to the fiber strain. Data acquisition and preprocessing are performed. The scattered light signal is converted into an electrical signal via a high-speed photoelectric converter, and the Brillouin frequency shift data distributed along the fiber are recorded. Digital filtering algorithms (such as wavelet transform) are used to remove environmental noise (such as seawater flow and temperature fluctuations) and equipment errors, retaining the valid frequency shift signal. Strain calculation and spatial positioning are performed, and the frequency shift data is fitted with a Lorentz curve to accurately extract the strain value corresponding to the frequency shift peak. Combining the optical fiber length and inclinometer position calibration information, the strain data is mapped to the physical coordinates of the steel sheet pile, generating a strain curve distributed along the pile shaft. Deformation analysis and result output are performed, and the strain data is compared with the preset safety threshold (displacement value) to automatically mark areas exceeding the limit. Time series analysis is used to predict the long-term deformation trend of the steel sheet pile and generate a deformation warning report (monitoring results).

[0065] It should be noted that Brillouin scattering is a type of inelastic scattering. It occurs when light in an optical fiber is affected by external strain and temperature, resulting in a frequency shift in the scattered light. BOTDA (Brillouin Optical Time-Domain Analysis) primarily analyzes and calculates the frequency shift of Brillouin scattered light to infer changes in the external medium environment, thereby enabling monitoring of deep soil deformation. The principle is to inject a continuous probe beam and a pulsed pump beam into the two ends of a sensing optical fiber, each transmitting in opposite directions. When the frequency difference between the two beams meets certain conditions, stimulated Brillouin scattering occurs, with some energy transferred from the higher-frequency pump light to the lower-frequency probe light. By measuring the power change of the probe light at each location on the fiber, the Brillouin gain at that location is determined. By scanning the frequency difference between the pump and probe lights, the Brillouin gain spectrum at each location in the fiber can be reconstructed. The Brillouin frequency shift at each location in the fiber can then be determined through fitting, ultimately achieving distributed strain sensing. When determining the Brillouin scattering frequency shift, a curve fitting algorithm is usually used, including a nonlinear least squares curve fitting method based on an error vector, a curve fitting method based on a neural network, and a generalized regression neural network curve fitting method based on a mutant fruit fly optimization algorithm. In addition, non-curve fitting methods can also be used, including cross-correlation methods, deep learning methods, and sub-pixel center of gravity algorithms. The automated system calculates the distribution of energy transfer in the optical fiber by detecting the information of the anti-Stokes light triggered by the Brillouin frequency shift and performing data processing, thereby realizing distributed monitoring of deformation along the line. The present application improves the PVC tube inclinometer used in traditional inclinometers, grooves the inner surface of the inclinometer tube, and installs the sensing optical fiber in the groove of the inclinometer tube with an adhesive.

[0066] The analyzer receives and records scattered light data from the fiber-optic sensing network. It automatically tracks and records changes in the Brillouin frequency shift along the fiber optic path. These changes directly reflect the strain state of the steel sheet pile along the fiber optic path. The collected data is first converted into electrical signals by a high-speed photoelectric converter and then fed into the data processing unit. Preliminary data processing, including filtering and denoising, is crucial for improving data quality. Preliminary analysis of the frequency shift data using specialized software identifies and eliminates anomalous data caused by environmental noise or equipment errors. The frequency shift data is then processed using the Lorentz fitting method to accurately calculate strain values. This stage of processing aims to provide clean, accurate data for subsequent in-depth analysis and interpretation.

[0067] Understandably, BOTDA technology exhibits significant performance advantages over traditional monitoring technologies. Not only does it significantly improve monitoring efficiency, but more importantly, it utilizes advanced distributed measurement technology, effectively overcoming the inherent drawbacks of traditional monitoring methods, such as lengthy processing times and discrete data collection. For example, traditional inclinometers employ a discrete monitoring approach (discrete monitoring involves placing discrete sensors or monitoring points at specific locations on the monitored object, using these individual points to obtain information about the object's state, enabling overall or local condition assessment). These sensors or monitoring points are distributed across limited, independent locations, rather than continuously covering the entire object, making it difficult to fully reflect overall deformation characteristics. However, BOTDA technology, leveraging the unique advantages of distributed measurement (distributed monitoring involves deploying continuous sensing units across the object to collect global state information and obtain spatially distributed data on physical quantities such as strain and displacement), enables continuous and comprehensive monitoring of steel sheet pile deformation throughout the entire depth range. The monitoring curve it generates is smooth and fluent, effectively avoiding the problems of data jumping and distortion in traditional deep deformation monitoring methods, thereby being able to present the true deformation situation of the entire section more accurately and intuitively.

[0068] Leveraging advanced optical time-domain analysis technology, BOTDA can automatically collect and analyze large amounts of data in a short period of time, completing a single monitoring session in far less time than traditional inclinometers. This reduces manual effort and provides a more intelligent, precise, and automated system. Traditional inclinometers, on the other hand, use a point-by-point measurement method, requiring manual labor and mechanical devices to collect data from each monitoring point in turn. This method is not only cumbersome but also time-consuming. In engineering scenarios requiring real-time or large-scale monitoring, traditional inclinometers are inefficient and unable to meet rapidly changing engineering needs. Therefore, BOTDA offers a clear advantage in monitoring speed, better meeting the demands of modern engineering projects for efficient, real-time monitoring.

[0069] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or N embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and features of different embodiments or examples without contradiction.

[0070] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of technical features indicated. Thus, a feature specified as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of this application, "N" means at least two, for example, two, three, etc., unless otherwise specifically defined.

[0071] Any process or method description in a flowchart or otherwise described herein may be understood to represent a module, fragment or portion of code comprising one or N executable instructions for implementing a custom logical function or process step, and the scope of the preferred embodiments of the present application includes alternative implementations in which functions may be performed in a different order than shown or discussed, including performing functions in a substantially simultaneous manner or in a reverse order depending on the functions involved, which should be understood by those skilled in the art to which the embodiments of the present application pertain.

[0072] The logic and / or steps represented in a flowchart or otherwise described herein, for example, can be considered a sequenced list of executable instructions for implementing the logical functions, and can be embodied in any computer-readable storage medium for use by, or in conjunction with, an instruction execution system, apparatus, or device (e.g., a computer-based system, a system including a processor, or other system that can fetch and execute instructions from an instruction execution system, apparatus, or device). For purposes of this specification, a "computer-readable storage medium" can be any device that can contain, store, communicate, propagate, or transport a program for use by, or in conjunction with, an instruction execution system, apparatus, or device. More specific examples (not exhaustive) of computer-readable storage media include the following: an electrical connection with one or more wires (electronic devices), a portable computer disk cartridge (magnetic device), random access memory (RAM), read-only memory (ROM), erasable and programmable read-only memory (EPROM or flash memory), fiber optic devices, and a portable compact disc read-only memory (CDROM). In addition, the computer-readable storage medium may even be paper or other suitable medium on which the program is printed, since the program can be obtained electronically by optically scanning the paper or other medium and then editing, interpreting or processing it in other suitable ways as necessary, and then storing it in a computer memory.

[0073] It should be understood that various parts of this application can be implemented using hardware, software, firmware, or a combination thereof. In the above embodiment, the N steps or methods can be implemented using software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented using hardware, as in another embodiment, any one of the following technologies known in the art or a combination thereof can be used: a discrete logic circuit having logic gate circuits for implementing logical functions on data signals, an application-specific integrated circuit having suitable combinational logic gate circuits, a programmable gate array (PGA), a field-programmable gate array (FPGA), etc.

[0074] Those skilled in the art will understand that all or part of the steps in the method of the above embodiment can be completed by instructing related hardware through a program, and the program can be stored in a computer-readable storage medium. When the program is executed, it includes one or a combination of the steps of the method embodiment.

[0075] In addition, the functional units in the various embodiments of the present application may be integrated into a processing module, or each unit may exist physically separately, or two or more units may be integrated into a module. The above-mentioned integrated module may be implemented in the form of hardware or in the form of a software functional module. If the integrated module is implemented in the form of a software functional module and sold or used as an independent product, it may also be stored in a computer-readable storage medium.

[0076] The storage medium mentioned above may be a read-only memory, a magnetic disk, or an optical disk, etc. Although the embodiments of the present application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present application. Persons skilled in the art may make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present application.

[0077] It should be understood that the application of this application is not limited to the above examples. For ordinary technicians in this field, they can make improvements or changes based on the above description. All these improvements and changes should fall within the scope of protection of the claims attached to this application.

[0078] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for monitoring sea area steel sheet pile cofferdam construction based on optical fiber sensing, characterized in that: The method for monitoring sea area steel sheet pile cofferdam construction based on optical fiber sensing includes: Installing a protective casing inside the steel sheet piles, and driving the steel sheet piles into the sea to form a sea area steel sheet pile cofferdam structure; Putting the prepared inclinometer casing into the protective casing and fixing it; Connecting one end of the optical fiber in the inclinometer tube to the pump light source interface of the analyzer, and connecting the other end of the optical fiber in the inclinometer tube to the continuous wave detection light source interface of the analyzer; The analyzer collects pump light data of the pulsed pump light and detection light data of the continuous detection light when transmitting pulsed pump light to one end of the optical fiber and transmitting continuous detection light to the other end of the optical fiber, and obtains a monitoring result of the deformation of the steel sheet pile cofferdam structure in the sea area based on the pump light data and the detection light data; The prepared inclinometer casing is placed in the protective casing and fixed, specifically comprising: Structural modification is performed on the original inclinometer tube, and at least one optical fiber is installed in the modified inclinometer tube to obtain a prepared inclinometer tube; Putting the inclinometer tube with the optical fiber installed into a galvanized steel pipe, and filling the gap between the inclinometer tube and the galvanized steel pipe with sand to fix it; A first optical fiber and a second optical fiber are installed in the inclinometer tube; The structural modification of the original inclinometer tube and installation of at least one optical fiber in the modified inclinometer tube to obtain a prepared inclinometer tube specifically includes: A first guide groove, a second guide groove, a third guide groove and a fourth guide groove are provided on the inner wall of the original inclinometer casing, wherein the first guide groove is symmetrically arranged with the second guide groove, and the third guide groove is symmetrically arranged with the fourth guide groove; Using adhesive to install the first optical fiber along the first guide groove and the second guide groove so that one end and the other end of the first optical fiber extend out of the inclinometer tube, and using adhesive to install the second optical fiber along the third guide groove and the fourth guide groove so that one end and the other end of the second optical fiber extend out of the inclinometer tube; The method of installing the first optical fiber along the first guide groove and the second guide groove using an adhesive so that one end and the other end of the first optical fiber extend out of the inclinometer tube, and installing the second optical fiber along the third guide groove and the fourth guide groove using an adhesive so that one end and the other end of the second optical fiber extend out of the inclinometer tube, specifically includes: Winding the middle section of the first optical fiber around the bottom end of the inclinometer tube, using adhesive to adhere the first section of the first optical fiber to the first guide groove so that the first guide groove is completely vertically covered by the first section of the first optical fiber, and using adhesive to adhere the tail section of the first optical fiber to the second guide groove so that the second guide groove is completely vertically covered by the tail section of the first optical fiber; Winding the middle section of the second optical fiber around the bottom end of the inclinometer tube, using adhesive to adhere the first section of the second optical fiber to the third guide groove so that the first guide groove is completely vertically covered by the first section of the second optical fiber, and using adhesive to adhere the tail section of the second optical fiber to the fourth guide groove so that the fourth guide groove is completely vertically covered by the tail section of the second optical fiber; One end of the first optical fiber extends out of the first guide groove, the other end of the first optical fiber extends out of the second guide groove, one end of the second optical fiber extends out of the third guide groove, and the other end of the second optical fiber extends out of the fourth guide groove.

2. The method for monitoring sea area steel sheet pile cofferdam construction based on optical fiber sensing according to claim 1 is characterized in that: The protective sleeve is a galvanized steel pipe; The protective sleeve is installed inside the steel sheet pile, specifically: A galvanized steel pipe is welded inside the steel sheet pile, wherein the diameter of the galvanized steel pipe is larger than the diameter of the inclinometer tube, and the diameter difference between the galvanized steel pipe and the inclinometer tube is within a set range.

3. The method for monitoring sea area steel sheet pile cofferdam construction based on optical fiber sensing according to claim 2 is characterized in that: The method further comprises: modifying the structure of the original inclinometer tube and installing at least one optical fiber in the modified inclinometer tube to obtain a prepared inclinometer tube; and then: A detachable protective cover is installed at the upper end of the inclinometer tube, and a sealing protective cover is installed at the lower end of the inclinometer tube.

4. The method for monitoring sea area steel sheet pile cofferdam construction based on optical fiber sensing according to claim 2 is characterized in that: The monitoring results of the deformation of the steel sheet pile cofferdam structure in the sea area are obtained based on the pump light data and the detection light data, specifically including: Calculating a frequency difference between the pulsed pump light and the continuous probe light according to the pump light data and the probe light data, and obtaining Brillouin frequency shift data according to the frequency difference; Obtaining strain data of the sea area steel sheet pile cofferdam structure according to the Brillouin frequency shift data; The monitoring results of the deformation of the steel sheet pile cofferdam structure in the sea area are obtained based on the strain data.

5. A marine steel sheet pile cofferdam structure deformation monitoring system, characterized in that: The marine steel sheet pile cofferdam structure deformation monitoring system includes a protective sleeve, an inclinometer tube, and an analyzer. The protective sleeve is used to be installed on the marine steel sheet pile. The inclinometer tube is sleeved in the protective sleeve. At least one optical fiber is connected to the inclinometer tube. One end of the optical fiber is connected to the pump light source interface of the analyzer, and the other end of the optical fiber is connected to the continuous wave detection light source interface of the analyzer. The analyzer is used to collect pump light data of the pulsed pump light and detection light data of the continuous detection light when transmitting pulsed pump light to one end of the optical fiber and transmitting continuous detection light to the other end of the optical fiber, and obtain monitoring results of the deformation of the steel sheet pile cofferdam structure in the sea area based on the pump light data and the detection light data.

6. The marine steel sheet pile cofferdam structure deformation monitoring system according to claim 5 is characterized in that: The protective sleeve is a galvanized steel pipe, the diameter of the galvanized steel pipe is larger than the diameter of the inclinometer tube, the diameter difference between the galvanized steel pipe and the inclinometer tube is within a set range, and sand is filled between the galvanized steel pipe and the inclinometer tube.

7. The marine steel sheet pile cofferdam structure deformation monitoring system according to claim 6 is characterized in that: A first optical fiber and a second optical fiber are installed in the inclinometer tube. A first guide groove, a second guide groove, a third guide groove, and a fourth guide groove are provided in the inclinometer tube. The first guide groove and the second guide groove are symmetrically arranged, and the third guide groove and the fourth guide groove are symmetrically arranged. The first section of the first optical fiber is installed in the first guide groove through an adhesive layer; the tail section of the first optical fiber is installed in the second guide groove through an adhesive layer, the first section of the second optical fiber is installed in the third guide groove through an adhesive layer, and the tail section of the second optical fiber is installed in the fourth guide groove through an adhesive layer. One end of the first optical fiber extends out of the first guide groove, and the other end of the first optical fiber extends out of the second guide groove. One end of the second optical fiber extends out of the third guide groove, and the other end of the second optical fiber extends out of the fourth guide groove.

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