Steel arch assembly type tunnel wireless intelligent monitoring system and method

Abstract

The application discloses a steel-arch-based assembled tunnel wireless intelligent monitoring system and method, relates to the technical field of tunnel engineering construction monitoring, and comprises a general adaptive base module, which is pre-welded to the inner side web surface of the initial support steel arch during the steel arch processing stage; an intelligent monitoring host module, which is detachably installed on the general adaptive base module through a quick-release connecting mechanism, and is internally integrated with a central processing unit, a power module, a wireless communication unit, a laser ranging unit, a MEMS attitude sensing unit and an alarm unit; the laser ranging unit is used for measuring the relative distance between another monitoring host on the same section of the opposite steel arch; and the MEMS attitude sensing unit is used for measuring the inclination angle of the monitoring point. The application adopts an assembled prefabricated structure, the base is pre-welded outside the steel arch field, the host can be installed and used immediately, drilling and bolting are not needed on site, the tunnel construction period is not occupied, and the construction efficiency is improved.

Description

Technical Field

[0001] This invention relates to the field of tunnel construction monitoring technology, specifically to a wireless intelligent monitoring system and method for prefabricated tunnels based on steel arch frames. Background Technology

[0002] With the rapid development of railway and highway tunnel engineering in China, surrounding rock monitoring and measurement has become a core technology for ensuring the stability of surrounding rock and controlling construction risks in the New Austrian Tunneling Method (NATM) tunnel construction. For soft surrounding rock sections such as loess and sandy loess, the surrounding rock deforms quickly and has weak self-stabilizing ability, requiring higher timeliness and completeness of monitoring data. Automated monitoring technology that can adapt to harsh working conditions has become an industry trend.

[0003] However, existing manual and wired automated monitoring technologies for tunnels have significant shortcomings in the narrow and multi-step construction scenarios of the three-stage method. Firstly, monitoring and construction are subject to significant interference, resulting in delayed and distorted initial readings. Traditional monitoring installation methods require the erection of the steel arch frame and shotcrete construction, followed by on-site drilling, installation of expansion bolts, and installation of measuring point hooks. This process typically necessitates suspending construction at the tunnel face, severely delaying the overall construction progress. Furthermore, the narrow construction space and numerous overlapping steps in the three-stage method often postpone the installation of monitoring points, directly resulting in the loss of crucial deformation data during the initial unloading of the surrounding rock, leading to severely delayed initial monitoring readings. Secondly, the layout... The challenges of on-site protection are significant. Existing automated monitoring instruments, such as hydrostatic levels and wired displacement gauges, require the laying of numerous signal and power cables on-site. The significant elevation difference at the three-tiered construction face, coupled with frequent operations by excavators, shotcrete trucks, and other construction machinery, makes monitoring cables highly susceptible to breakage and damage from being pulled or crushed. This results in high equipment protection difficulty and poor operational stability. Furthermore, the on-site survival rate of the equipment is low. Shotcrete operations in tunnels generate large amounts of slurry splashes and dust, which easily cover monitoring points and contaminate sensor lenses, making it difficult to locate measuring points and causing instrument failure. This hinders long-term effective monitoring and fails to meet the demands of routine, high-precision construction safety monitoring in tunnels. To address these challenges, we propose a prefabricated wireless intelligent monitoring system and method for tunnels based on steel arch frames. Summary of the Invention

[0004] To address the aforementioned technical problems, a prefabricated wireless intelligent monitoring system and method for tunnels based on steel arch frames is provided. This technical solution solves the problems of tunnel monitoring interference during construction, difficult wiring, and easy equipment failure.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: The prefabricated tunnel wireless intelligent monitoring system based on steel arch frames includes: The universal adapter base module is pre-welded to the inner web surface of the initial support steel arch during the steel arch processing stage. The intelligent monitoring host module can be detachably installed on a universal adapter base module via a quick-release connection mechanism. It integrates a central processing unit, a power module, a wireless communication unit, a laser ranging unit, a MEMS attitude sensing unit, and an alarm unit. The laser ranging unit is used to measure the relative distance between the host and another monitoring unit on the same cross section of the opposite steel arch. The MEMS attitude sensing unit is used to measure the tilt angle of the monitoring point. The anti-spraying protection module is located at the front end of the intelligent monitoring host module and includes an openable and closable mechanical cover plate. In the closed state, the mechanical cover plate seals and blocks the observation window of the laser ranging unit. Its outer surface protrudes from the plane of the steel arch frame flange plate, serving as a control reference plane for the thickness of the sprayed concrete. In the open state, the observation window is exposed for measurement.

[0006] Preferably, the universal adapter base module has a U-shaped groove structure with its opening facing the inside of the tunnel; The universal adapter base module is pre-welded to the inner web of the steel arch frame during the steel arch frame processing stage by fillet weld. Its installation depth ensures that the front end of the intelligent monitoring host module does not exceed the outer edge of the upper and lower flange plates of the steel arch frame, and forms external physical protection by relying on the upper and lower flange plates of the steel arch frame.

[0007] Preferably, the housing of the intelligent monitoring host module is provided with guide rail structures on both sides that match the U-shaped slide groove of the universal adapter base module, forming a quick-release connection mechanism; The intelligent monitoring host module is installed by sliding and plugging in the guide rail, and uses a spring pin or magnetic structure to achieve self-locking during installation. After assembly, the whole unit is fixed in a limited position. The housing protection level of the intelligent monitoring host module is IP68.

[0008] Preferably, the central processing unit is the core control unit of the system, used to receive data from each sensing unit, perform data calculation, storage, and limit judgment; The power module uses a lithium thionyl chloride battery pack with a sleep control circuit to provide continuous power to the whole device and support low-power sleep wake-up; the wireless communication unit supports ZigBee / Bluetooth Mesh short-range self-organizing network protocol and LoRa long-range transmission protocol; Multiple intelligent monitoring host modules at the same monitoring section form a local area network. The intelligent monitoring host module located at the top of the tunnel is configured as the master node, and the other intelligent monitoring host modules are configured as slave nodes. The master node will collect the data and upload it to the relay gateway in the tunnel through the LoRa long-distance transmission protocol, and then the relay gateway will forward it to the remote monitoring platform. The intelligent monitoring host module has a trigger wake-up mode. When the anti-spraying protection module switches from the closed state to the open state, the light sensor or Hall sensor detects the state change, automatically triggers the system to power on and collects the initial readings.

[0009] Preferably, the laser ranging unit is arranged at the front end of the intelligent monitoring host module, aligned with another monitoring host module on the opposite side of the same cross section, and collects the change in the distance between the two devices in real time through laser beam, thereby obtaining data on the change in tunnel clearance convergence.

[0010] Preferably, the MEMS attitude sensing unit is a dual-axis tilt sensor, which is fixedly arranged inside the intelligent monitoring host module to collect the change in tangent angle at the monitoring point of the steel arch in real time, providing raw attitude data for the inverse calculation of the deformation of the tunnel steel frame and the settlement of the arch.

[0011] Preferably, the anti-spraying protection module is hinged to the front end of the universal adapter base module or the intelligent monitoring host module via a damping hinge, and the damping hinge supports the mechanical cover plate to be suspended at any angle. The inner side of the mechanical cover is inlaid with a silicone pad, which can completely fit the front end face of the intelligent monitoring host module when closed, achieving full-sealed protection of the observation window. The outer surface of the mechanical cover is coated with Teflon and has a red handle.

[0012] Preferably, the mechanical cover plate has two working states: closed and open. In the closed state, the mechanical cover plate completely seals and blocks the observation window of the laser ranging unit, preventing the sprayed concrete slurry and dust pollution. The outer surface of the cover plate protrudes from the plane of the steel arch flange plate. Using the outer surface of the cover plate as a reference plane, the thickness of the sprayed concrete on site can be visualized and controlled. When open, the mechanical cover flips to avoid obstruction, fully exposing the observation window of the laser ranging unit, thus meeting the requirements for tunnel cross-section distance measurement operations.

[0013] Preferably, the method for wireless intelligent monitoring of prefabricated tunnels based on steel arch frames includes the following steps: S1. Prefabrication stage: At the steel arch frame processing plant, based on the design mileage of the monitoring section, the universal adapter base module is pre-welded to the predetermined position on the inner web of the steel arch frame to form the off-site prefabrication layout of the monitoring points. S2. Installation stage: When the steel arch frame is erected after the tunnel excavation, the intelligent monitoring host is slid into the welded universal adapter base module through the guide rail, and the anti-spraying protection module is placed in the closed state by the self-locking position of the spring pin or magnetic structure. S3, Protection and Construction Phase: Shotcrete operation is carried out, and concrete covers the steel arch and the perimeter of the system. The anti-spraying protection module, which is in a closed state, is used to block the observation window of the laser ranging unit from being contaminated by shotcrete slurry and dust. S4. Activation and Initial Reading Stage: After the shotcrete operation is completed, clean the laitance on the surface of the anti-shotcrete protection module and turn it on; the light sensor or Hall sensor detects the state change, automatically triggers the system to power on and performs laser beam and attitude measurement to obtain the initial convergence value L0 and the initial tilt angle value θ0. S5. Automated Monitoring Phase: The system automatically acquires the convergence distance L between the two monitoring hosts according to a preset acquisition frequency. t and the tilt angle θ of the monitoring point t The main node intelligent monitoring host module located on the arch aggregates data from each slave node in this section through the ZigBee / BluetoothMesh short-range self-organizing network protocol, and then uploads the aggregated data to the relay gateway in the tunnel through the LoRa long-distance transmission protocol. Finally, the relay gateway forwards the data to the remote monitoring platform.

[0014] Preferably, step S5 further includes a step of calculating and classifying the settlement of the arch based on multi-source sensor fusion: The change in tangent angle Δθ at the arch foot node of the steel arch frame is obtained using a MEMS attitude sensing unit; the change in clearance convergence ΔL between the two monitoring hosts is obtained using a laser ranging unit. Based on the geometric constraints of the steel arch frame as a rigid link, a displacement calculation model is established. Assuming the arc length of the steel arch frame remains constant, the net clearance convergence change ΔL, the tangent angle change Δθ, and the design curvature radius R of the steel arch frame are used as joint inputs to calculate the vertical settlement ΔV at the arch top node. The calculation formula is as follows: ΔV = f(ΔL, Δθ, R) When the rate of vertical settlement ΔV or the rate of change in net clearance convergence ΔL exceeds the preset threshold, the alarm unit triggers the corresponding action according to the preset alarm level: local audible and visual alerts during yellow alerts, alarm information is simultaneously uploaded via wireless communication unit during orange alerts, and emergency response procedures are triggered in conjunction with red alerts.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention employs a prefabricated assembly structure. The universally compatible base module is pre-welded during the off-site processing of the steel arch frame, eliminating the need for cumbersome operations such as drilling and bolting on the construction site. The intelligent monitoring host module can be erected and used immediately without interfering with the tunnel excavation and support cycle, effectively improving overall construction efficiency. Utilizing the upper and lower flanges of the steel arch frame to form natural collision protection, coupled with an openable anti-spraying protection module, it effectively resists spraying slurry, dust pollution, and impacts from falling rocks and mechanical scraping, preventing sensor failure and significantly improving the equipment's operational stability under harsh tunnel construction conditions. No delayed deployment is required. Once the measuring points are set up and the protective module is activated after the shotcrete construction is completed, it can automatically power on and collect initial readings. It can accurately capture the minute deformations in the early stage of unloading of the surrounding rock, solving the problems of lagging initial readings and missing early deformation data in traditional monitoring. It provides continuous and reliable raw data support for the assessment of surrounding rock stability. It adopts a battery-powered and wireless transmission architecture, relying on short-range self-organizing network protocol and LoRa long-range transmission protocol to complete data aggregation and uploading. It completely eliminates the need for wired cable laying and avoids the problems of cable damage and difficult wiring in the three-step construction scenario, realizing automated, wireless and stable transmission of monitoring data. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the system modules of the present invention; Figure 2 This is a schematic cross-sectional view of the device of the present invention installed inside an I-beam arch frame; Figure 3 This is an exploded structural diagram of the device of the present invention; Figure 4 This is a schematic diagram of the layout and network of the device of the present invention in a tunnel constructed using the three-stage method; Figure 5 This is a flowchart of the monitoring method of the present invention. Detailed Implementation

[0017] The following description is intended to disclose the invention and enable those skilled in the art to implement it. The preferred embodiments described below are merely examples, and other obvious variations will occur to those skilled in the art.

[0018] Reference Figure 1 As shown, the prefabricated tunnel wireless intelligent monitoring system based on steel arch frames includes: The universal adapter base module is pre-welded to the inner web surface of the initial support steel arch during the steel arch processing stage. The intelligent monitoring host module can be detachably installed on a universal adapter base module via a quick-release connection mechanism. It integrates a central processing unit, a power module, a wireless communication unit, a laser ranging unit, a MEMS attitude sensing unit, and an alarm unit. The laser ranging unit is used to measure the relative distance between the host and another monitoring unit on the same cross section of the opposite steel arch. The MEMS attitude sensing unit is used to measure the tilt angle of the monitoring point. The anti-spraying protection module is located at the front end of the intelligent monitoring host module and includes an openable and closable mechanical cover plate. In the closed state, the mechanical cover plate seals and blocks the observation window of the laser ranging unit. Its outer surface protrudes from the plane of the steel arch frame flange plate, serving as a control reference plane for the thickness of the sprayed concrete. In the open state, the observation window is exposed for measurement.

[0019] Example 1: Device Structure The universal adapter base module has a U-shaped sliding groove structure with its opening facing the inside of the tunnel. The universal adapter base module is pre-welded to the inner web of the steel arch frame during the steel arch frame processing stage by fillet weld. Its installation depth ensures that the front end of the intelligent monitoring host module does not exceed the outer edge of the upper and lower flange plates of the steel arch frame, and forms external physical protection by relying on the upper and lower flange plates of the steel arch frame.

[0020] The universal adapter base module 100 is made of Q235 steel plate through bending and forming, with a wall thickness of 4mm. In this embodiment, the initial support steel arch frame is an I20b I-beam, and the welding operation is completed during the steel arch frame processing stage, without taking up working time inside the tunnel. The installation depth of the base 100 has been designed and verified: the opening edge of the U-shaped groove ensures that the front end of the installed intelligent monitoring host module 200 does not exceed the outer edge of the I-beam flange plate 12, thereby relying on the upper and lower flange plates 12 of the steel arch frame to form external physical protection for the intelligent monitoring host module 200, realizing the hidden protection arrangement of the monitoring point.

[0021] The housing of the intelligent monitoring host module is equipped with guide rail structures on both sides that match the U-shaped slide grooves of the universal adapter base module, forming a quick-release connection mechanism; The intelligent monitoring host module is installed by sliding and plugging in the guide rail, and uses a spring pin or magnetic structure to achieve self-locking during installation. After assembly, the whole unit is fixed in a limited position. The housing protection level of the intelligent monitoring host module is IP68.

[0022] The outer shell is made of die-cast aluminum alloy. Guide rails 201 are set on both sides of the main body shell, which cooperate with the U-shaped sliding groove of the base 100 to form a quick-release connection mechanism. During on-site installation, the monitoring personnel slide the guide rail 201 along the U-shaped groove of the base 100 and insert it into place. The installation is self-locked by spring pins or magnetic attraction structure. After assembly, the whole is fixed in a limited position. The monitoring personnel can quickly complete the installation and replacement of the main module by one person. If it is necessary to replace the battery, upgrade the firmware or repair the fault of the main module during the monitoring period, the main module can be slid out in the opposite direction along the U-shaped groove without damaging the steel arch frame and the shotcrete layer.

[0023] The central processing unit is the core control unit of the system, used to receive data from each sensing unit, perform data processing, storage, and limit judgment; The power module uses a lithium thionyl chloride battery pack with a sleep control circuit to provide continuous power to the whole device and support low-power sleep wake-up; the wireless communication unit supports ZigBee / Bluetooth Mesh short-range self-organizing network protocol and LoRa long-range transmission protocol; Multiple intelligent monitoring host modules at the same monitoring section form a local area network. The intelligent monitoring host module located at the top of the tunnel is configured as the master node, and the other intelligent monitoring host modules are configured as slave nodes. The master node will collect the data and upload it to the relay gateway in the tunnel through the LoRa long-distance transmission protocol, and then the relay gateway will forward it to the remote monitoring platform. The intelligent monitoring host module has a trigger wake-up mode. When the anti-spraying protection module switches from the closed state to the open state, the light sensor or Hall sensor detects the state change, automatically triggers the system to power on and collects the initial readings.

[0024] The alarm unit includes a high-brightness LED strobe light, which can realize local audible and visual alarm functions; For example, the power module uses a 3.6V / 19Ah lithium thionyl chloride battery pack; at the preferred acquisition frequency of 1 time / hour, the equipment can work continuously for 12 months, meeting the maintenance-free requirements within a typical tunnel construction monitoring cycle; The wireless communication unit supports ZigBee / Bluetooth Mesh short-range self-organizing network protocol and LoRa long-range transmission protocol. For example, the LoRa communication module preferably operates at a frequency of 433MHz / 470MHz. The short-range protocol is used for data aggregation between multiple host modules within this monitoring section, and the long-range protocol is used to upload the aggregated data to a remote monitoring platform. Multiple intelligent monitoring host modules in the same monitoring section form a ZigBee local area network. When the mechanical cover of the anti-spraying protection module 300 switches from the closed state to the open state, the observation area sensed by the light sensor switches from the dark state to the bright state.

[0025] The laser ranging unit is positioned at the front end of the intelligent monitoring host module, aligned with another monitoring host module on the opposite side of the same cross section. It collects the changes in the distance between the two devices in real time through laser beam transmission, thereby obtaining data on the changes in tunnel clearance convergence.

[0026] The intelligent monitoring host module 200 integrates a laser ranging module (i.e., laser ranging unit). For example, the laser ranging unit has a range of 0.2~30m and a measurement accuracy of ±1mm.

[0027] The MEMS attitude sensing unit is a dual-axis tilt sensor, fixedly arranged inside the intelligent monitoring host module. It collects the changes in the tangent angle of the steel arch monitoring points in real time, providing raw attitude data for the back calculation of tunnel steel frame deformation and arch settlement.

[0028] The intelligent monitoring host module 200 integrates a MEMS dual-axis tilt sensor (i.e., a MEMS attitude sensing unit). For example, the tilt sensor has a measurement range of ±30° and a resolution of 0.001°.

[0029] The anti-spraying protection module is hinged to the front of the universal adapter base module or the intelligent monitoring host module via a damping hinge. The damping hinge supports the mechanical cover plate to be suspended at any angle. The inner side of the mechanical cover is inlaid with a silicone pad, which can completely fit the front end face of the intelligent monitoring host module when closed, achieving full-sealed protection of the observation window. The outer surface of the mechanical cover is coated with Teflon and has a red handle.

[0030] The anti-spraying protection module 300 includes a mechanical cover plate that is hinged to the front end of the universal adapter base module 100 or the intelligent monitoring host module 200 via a damping hinge. After the mechanical cover is closed, it can completely fit the observation window (i.e., the glass window area). The outer surface of the mechanical cover is coated with Teflon, which can effectively prevent the sprayed concrete slurry from sticking to the surface of the cover. The mechanical cover is also equipped with a red handle, which makes it easy for on-site workers to quickly identify and open the mechanical cover after the spraying is completed.

[0031] The mechanical cover plate has two working states: closed and open. In the closed state, the mechanical cover plate completely seals and blocks the observation window of the laser ranging unit, preventing sprayed concrete slurry and dust pollution. The outer surface of the cover plate protrudes from the plane of the steel arch frame flange plate. Using the outer surface of the cover plate as the reference plane, the thickness of the sprayed concrete on site can be visualized and controlled. When open, the mechanical cover flips to avoid obstruction, fully exposing the observation window of the laser ranging unit, thus meeting the requirements for tunnel cross-section distance measurement operations.

[0032] Visual control of shotcrete thickness on site refers to the process by which on-site workers use the outer surface of the cover plate as a reference to control the thickness of the shotcrete coating to not exceed that reference surface.

[0033] Example 2: Monitoring section layout and network in three-stage construction For tunnels constructed using the three-stage method, this system adopts a distributed self-organizing network layout.

[0034] The monitoring section adopts a 7-node distributed deployment method, with 7 nodes arranged on a typical monitoring section. In this embodiment, the nodes are denoted as N1 to N7 respectively: Arch crown node N1 is installed at the center of the upper step arch crown steel frame; upper step arch foot nodes N2 and N3 are installed 1m above the arch feet on both sides of the upper step steel frame; middle step nodes N4 and N5 are installed on both sides of the middle step steel frame; lower step nodes N6 and N7 are installed on both sides of the lower step steel frame. The universal adapter base 100 for each node has been pre-welded off-site at the steel arch frame processing plant and transported to the site for installation along with the steel arch frame.

[0035] ZigBee LAN networking After all nodes are powered on, they automatically search for and join the network via the ZigBee protocol. The intelligent monitoring host module located at the dome is configured as the master node, namely N1, and the other intelligent monitoring host modules are configured as slave nodes. The slave nodes send the data they collect, including laser distance, battery level, tilt angle, etc., to the master node N1.

[0036] LoRa long-distance data transmission The main node N1 has a built-in LoRa module with a working frequency of 433MHz / 470MHz. A relay gateway is installed on the tunnel lining trolley or the invert arch trestle. The N1 node sends the aggregated data to the relay gateway via LoRa signal. The relay gateway then uploads the data to the remote monitoring platform through the optical fiber network in the tunnel, realizing remote centralized management and real-time viewing of the monitoring data.

[0037] Example 3: Specific Flowchart of the Monitoring Method S1. Prefabrication stage: At the steel arch frame processing plant, based on the design mileage of the monitoring section, the universal adapter base module is pre-welded to the predetermined position on the inner web of the steel arch frame to form the off-site prefabrication layout of the monitoring points. S2. Installation stage: When the steel arch frame is erected after the tunnel excavation, the intelligent monitoring host is slid into the welded universal adapter base module through the guide rail, and the anti-spraying protection module is placed in the closed state by the self-locking position of the spring pin or magnetic structure. S3, Protection and Construction Phase: Shotcrete operation is carried out, and concrete covers the steel arch and the surrounding area of ​​the system. The anti-shotcrete protection module, which is in a closed state, blocks the observation window of the laser ranging unit from being contaminated by shotcrete slurry and dust. S4. Activation and Initial Reading Stage: After the shotcrete operation is completed, clean the laitance on the surface of the anti-shotcrete protection module and turn it on; the light sensor or Hall sensor detects the state change, automatically triggers the system to power on and performs laser beam and attitude measurement to obtain the initial convergence value L0 and the initial tilt angle value θ0. S5. Automated Monitoring Phase: The system automatically acquires the convergence distance L between the two monitoring hosts according to a preset acquisition frequency. t and the tilt angle θ of the monitoring point t The main node intelligent monitoring host module located on the arch aggregates data from each slave node in this section through the ZigBee / BluetoothMesh short-range self-organizing network protocol, and then uploads the aggregated data to the relay gateway in the tunnel through the LoRa long-distance transmission protocol. Finally, the relay gateway forwards the data to the remote monitoring platform.

[0038] The predetermined position refers to the workers welding the universal adapter base 100 to a specific position on the steel arch frame using a positioning mold according to the design drawings. This step does not take up any working time in the tunnel. The mechanical cover completely seals and blocks the observation window of the laser ranging unit. At the same time, the outer surface of the cover, which protrudes from the plane of the steel arch flange plate, also serves as a physical reference (i.e., the reference surface for shotcrete thickness) for controlling the thickness of the shotcrete. The light sensor inside the host detects a sudden change in light, switching from a dark state where the mechanical cover is blocked to a bright state where the mechanical cover is open. It automatically wakes up from deep sleep mode and performs a self-test. After passing the self-test, it performs laser beam refraction and attitude measurement. The initial convergence value L0 is obtained as the initial distance between the laser beam refraction of the two opposing monitoring hosts. The initial tilt angle value θ0 is the initial tangent angle of the monitoring point, which serves as the reference reading for the subsequent automated monitoring stage. The preset acquisition frequency is 1 time / hour.

[0039] Step S5 also includes a step of calculating and classifying the settlement of the arch based on multi-source sensor fusion: The change in tangent angle Δθ at the arch foot node of the steel arch frame is obtained using a MEMS attitude sensing unit; the change in clearance convergence ΔL between the two monitoring hosts is obtained using a laser ranging unit. Based on the geometric constraints of the steel arch frame as a rigid link, a displacement calculation model is established. Assuming the arc length of the steel arch frame remains constant, the net clearance convergence change ΔL, the tangent angle change Δθ, and the design curvature radius R of the steel arch frame are used as joint inputs to calculate the vertical settlement ΔV at the arch top node. The calculation formula is as follows: ΔV = f(ΔL, Δθ, R) When the rate of vertical settlement ΔV or the rate of change in net clearance convergence ΔL exceeds the preset threshold, the alarm unit triggers the corresponding action according to the preset alarm level: local audible and visual alerts during yellow alerts, alarm information is simultaneously uploaded via wireless communication unit during orange alerts, and emergency response procedures are triggered in conjunction with red alerts.

[0040] The arch foot nodes are N2 and N3, and the tangent angle is θ. t and convergence distance L t By comparing the values ​​with the initial values ​​obtained in stage S4, the change in the tangent angle Δθ = θ is obtained. t -θ0 and the net clearance convergence change ΔL=L t -L0; Using a rigid body rotation model, assuming the arc length of the steel arch remains constant, the vertical settlement ΔV of the arch top node (e.g., N1) can be calculated by jointly solving Δθ and ΔL. The calculation formula is as follows: ΔV = f(ΔL, Δθ, R) The warning threshold of this invention is determined by referring to the three-level warning standards such as DB14 / T 3510-2025 "Technical Specification for Monitoring and Measurement of Highway Tunnels" and the Guangdong Provincial Technical Guidelines for Highway Tunnel Structure Monitoring, and is comprehensively determined in conjunction with the alarm parameters of the 5mm / d high-brightness LED strobe light in the embodiment, as follows: Yellow alert: ΔV or ΔL rate > 3mm / d, local audio and visual alerts will be issued on the equipment. Orange alert: When the ΔV or ΔL rate is greater than 5 mm / d, a high-brightness LED strobe light will be activated and the alert information will be uploaded to the remote monitoring platform simultaneously. Red alert: ΔV or ΔL velocity > 10 mm / d, triggering on-site emergency response procedures.

[0041] Example 4: Extended Implementation Compatible with grating steel frame For tunnel applications using lattice steel frames, the welding surface of the universal adapter base module can be modified to a clamp structure, enabling it to be clamped onto the main reinforcement of the lattice steel frame, thus achieving off-site prefabrication functionality similar to that of the I-beam scheme.

[0042] Mobile data mule mode For tunnels without fiber optic cables, the intelligent monitoring host module can be configured as a store-and-forward mode: the module saves the monitoring data to local storage at a preset acquisition frequency; when an underground transport vehicle (typically a muck truck) passes by, if the vehicle is equipped with a specific Bluetooth beacon, the host module detects the beacon through Bluetooth Mesh and quickly sends the stored historical data to the vehicle. After the vehicle takes the data out of the tunnel, it is automatically uploaded to the remote monitoring platform, realizing the function of data transmission back to the vehicle.

[0043] Reference Figure 2The diagram shown is a cross-sectional view of the device of the present invention installed inside the I-beam arch frame, illustrating the fixing method of the adapter base and the I-beam arch frame, as well as the positional relationship between the main unit, the protective cover and the base. After spraying, the protective cover can protect the main unit.

[0044] Reference Figure 3 The diagram shown is an exploded view of the device of the present invention, clearly demonstrating the assembly relationship between the adapter base, the intelligent monitoring host, and the protective cover: the host can be inserted and installed along the sliding groove of the base, and the protective cover is hinged to the front end of the host and can be opened and closed.

[0045] Reference Figure 4 The diagram shows the node arrangement and networking of the device of the present invention in a tunnel constructed using the three-step method. It illustrates the layout of the main node at the top of the arch and the slave nodes of each step, as well as the communication relationship between the ZigBee self-organizing network and the LoRa backhaul to the mobile gateway.

[0046] Reference Figure 5 The diagram shown is a flowchart of the monitoring method of the present invention, illustrating the complete logical steps from off-site prefabrication, on-site installation, shotcrete protection, cover plate opening and activation, initial reading acquisition, to periodic automatic monitoring.

[0047] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention. The scope of protection claimed by the appended claims and their equivalents is defined.

Claims

1. A prefabricated tunnel wireless intelligent monitoring system based on a steel arch frame, characterized in that, include: The universal adapter base module is pre-welded to the inner web surface of the initial support steel arch during the steel arch processing stage. The intelligent monitoring host module can be detachably installed on a universal adapter base module via a quick-release connection mechanism. It integrates a central processing unit, a power module, a wireless communication unit, a laser ranging unit, a MEMS attitude sensing unit, and an alarm unit. The laser ranging unit is used to measure the relative distance between the host and another monitoring unit on the same cross section of the opposite steel arch. The MEMS attitude sensing unit is used to measure the tilt angle of the monitoring point. The anti-spraying protection module is located at the front end of the intelligent monitoring host module and includes an openable and closable mechanical cover plate; when closed, the mechanical cover plate seals and blocks the observation window of the laser ranging unit. Its outer surface protrudes from the plane of the steel arch flange plate, serving as a reference surface for controlling the thickness of the shotcrete; when open, the observation window is exposed for measurement.

2. The prefabricated tunnel wireless intelligent monitoring system based on steel arch frame according to claim 1, characterized in that, The universal adapter base module has a U-shaped sliding groove structure with its opening facing the inside of the tunnel. The universal adapter base module is pre-welded to the inner web of the steel arch frame during the steel arch frame processing stage by fillet weld. Its installation depth ensures that the front end of the intelligent monitoring host module does not exceed the outer edge of the upper and lower flange plates of the steel arch frame, and forms external physical protection by relying on the upper and lower flange plates of the steel arch frame.

3. The prefabricated tunnel wireless intelligent monitoring system based on steel arch frame according to claim 1, characterized in that, The housing of the intelligent monitoring host module is equipped with guide rail structures on both sides that match the U-shaped slide grooves of the universal adapter base module, forming a quick-release connection mechanism; The intelligent monitoring host module is installed by sliding and plugging in the guide rail, and uses a spring pin or magnetic structure to achieve self-locking during installation. After assembly, the whole unit is fixed in a limited position. The housing protection level of the intelligent monitoring host module is IP68.

4. The prefabricated tunnel wireless intelligent monitoring system based on steel arch frame according to claim 1, characterized in that, The central processing unit is the core control unit of the system, used to receive data from each sensing unit, perform data processing, storage, and limit judgment; The power module uses a lithium thionyl chloride battery pack with a sleep control circuit to provide continuous power to the whole machine and support low-power sleep wake-up; The wireless communication unit supports ZigBee / Bluetooth Mesh short-range self-organizing network protocol and LoRa long-range transmission protocol; Multiple intelligent monitoring host modules at the same monitoring section form a local area network. The intelligent monitoring host module located at the top of the tunnel is configured as the master node, and the other intelligent monitoring host modules are configured as slave nodes. The master node will collect the data and upload it to the relay gateway in the tunnel through the LoRa long-distance transmission protocol, and then the relay gateway will forward it to the remote monitoring platform. The intelligent monitoring host module has a trigger wake-up mode. When the anti-spraying protection module switches from the closed state to the open state, the light sensor or Hall sensor detects the state change, automatically triggers the system to power on and collects the initial readings.

5. The prefabricated tunnel wireless intelligent monitoring system based on steel arch frame according to claim 1, characterized in that, The laser ranging unit is positioned at the front end of the intelligent monitoring host module, aligned with another monitoring host module on the opposite side of the same cross section. It collects the changes in the distance between the two devices in real time through laser beam transmission, thereby obtaining data on the changes in tunnel clearance convergence.

6. The prefabricated tunnel wireless intelligent monitoring system based on steel arch frame according to claim 1, characterized in that, The MEMS attitude sensing unit is a dual-axis tilt sensor, fixedly arranged inside the intelligent monitoring host module. It collects the changes in the tangent angle of the steel arch monitoring points in real time, providing raw attitude data for the back calculation of tunnel steel frame deformation and arch settlement.

7. The prefabricated tunnel wireless intelligent monitoring system based on steel arch frame according to claim 1, characterized in that, The anti-spraying protection module is hinged to the front of the universal adapter base module or the intelligent monitoring host module via a damping hinge. The damping hinge supports the mechanical cover plate to be suspended at any angle. The inner side of the mechanical cover is inlaid with a silicone pad, which can completely fit the front end face of the intelligent monitoring host module when closed, achieving full-sealed protection of the observation window. The outer surface of the mechanical cover is coated with Teflon and has a red handle.

8. The prefabricated tunnel wireless intelligent monitoring system based on steel arch frame according to claim 1, characterized in that, The mechanical cover plate has two working states: closed and open. In the closed state, the mechanical cover plate completely seals and blocks the observation window of the laser ranging unit, preventing sprayed concrete slurry and dust pollution. The outer surface of the cover plate protrudes from the plane of the steel arch frame flange plate. Using the outer surface of the cover plate as the reference plane, the thickness of the sprayed concrete on site can be visualized and controlled. When open, the mechanical cover flips to avoid obstruction, fully exposing the observation window of the laser ranging unit, thus meeting the requirements for tunnel cross-section distance measurement operations.

9. A method for wireless intelligent monitoring of prefabricated tunnels based on steel arch frames, applied to the wireless intelligent monitoring system for prefabricated tunnels based on steel arch frames as described in any one of claims 1-8, characterized in that the steps... include: S1. Prefabrication stage: At the steel arch frame processing plant, based on the design mileage of the monitoring section, the universal adapter base module is pre-welded to the predetermined position on the inner web of the steel arch frame to form the off-site prefabrication layout of the monitoring points. S2. Installation stage: When the steel arch frame is erected after the tunnel excavation, the intelligent monitoring host is slid into the welded universal adapter base module through the guide rail, and the anti-spraying protection module is placed in the closed state by the self-locking position of the spring pin or magnetic structure. S3, Protection and Construction Phase: Shotcrete operation is carried out, and concrete covers the steel arch and the perimeter of the system. The anti-spraying protection module, which is in a closed state, is used to block the observation window of the laser ranging unit from being contaminated by shotcrete slurry and dust. S4. Activation and Initial Reading Stage: After the shotcrete operation is completed, clean the laitance on the surface of the anti-shotcrete protection module and turn it on; the light sensor or Hall sensor detects the state change, automatically triggers the system to power on and performs laser beam and attitude measurement to obtain the initial convergence value L0 and the initial tilt angle value θ0. S5. Automated Monitoring Phase: The system automatically acquires the convergence distance L between the two monitoring hosts according to a preset acquisition frequency. t and the tilt angle θ of the monitoring point t The main node intelligent monitoring host module located on the arch aggregates data from each slave node in this section through the ZigBee / Bluetooth Mesh short-range self-organizing network protocol, and then uploads the aggregated data to the relay gateway in the tunnel through the LoRa long-distance transmission protocol. Finally, the relay gateway forwards the data to the remote monitoring platform.

10. The prefabricated tunnel wireless intelligent monitoring method based on steel arch frame according to claim 9, characterized in that, Step S5 also includes a step of calculating and classifying the settlement of the arch based on multi-source sensor fusion: The change in tangent angle Δθ at the arch foot node of the steel arch frame is obtained using a MEMS attitude sensing unit; the change in clearance convergence ΔL between the two monitoring hosts is obtained using a laser ranging unit. Based on the geometric constraints of the steel arch frame as a rigid link, a displacement calculation model is established. Assuming the arc length of the steel arch frame remains constant, the net clearance convergence change ΔL, the tangent angle change Δθ, and the design curvature radius R of the steel arch frame are used as joint inputs to calculate the vertical settlement ΔV at the arch top node. The calculation formula is as follows: ΔV = f(ΔL, Δθ, R) When the rate of vertical settlement ΔV or the rate of change in net clearance convergence ΔL exceeds the preset threshold, the alarm unit triggers the corresponding action according to the preset alarm level: local audible and visual alerts during yellow alerts, alarm information is simultaneously uploaded via wireless communication unit during orange alerts, and emergency response procedures are triggered in conjunction with red alerts.

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