Automatic monitoring system for tunnel surrounding rock and primary support deformation in construction period

Abstract

The invention relates to the technical field of tunnel engineering construction monitoring, and discloses an automatic monitoring system for tunnel surrounding rock and primary support deformation in a construction period, which comprises an image acquisition and analysis unit arranged in a stable area, a ground reference unit and a primary support deformation monitoring and auxiliary lighting unit, the surrounding rock deformation monitoring unit is arranged in the primary support area and comprises a reflective target; and the primary support deformation monitoring and auxiliary illumination unit projects structured light to the surface of the primary support and illuminates the reflective target. An image unit is combined with a ground reference to carry out space resection so as to correct the position and posture of an observation station in real time, deep hole anchoring of a reflective target is matched with an isolation sleeve structure to realize deformation decoupling of a deep surrounding rock and a primary support structure, and narrow-band filtering and a time division multiplexing acquisition strategy are combined; the problems that the reference is unstable and the multi-dimensional features are difficult to synchronize in the construction environment are solved, and high-precision and high-stability automatic monitoring is achieved.

Description

Technical Field

[0001] This invention relates to the field of tunnel construction monitoring technology, specifically an automated monitoring system for the deformation of the surrounding rock and initial support of a tunnel during the construction period. Background Technology

[0002] In tunnel and underground engineering construction, deformation monitoring of the surrounding rock and support structure is a core component of the New Austrian Tunneling Method (NATM), playing a crucial role in assessing rock stability, verifying the rationality of support parameters, and ensuring construction safety. As tunnel construction moves towards mechanization and automation, non-contact automated monitoring technologies based on total stations, 3D laser scanners, or machine vision are gradually replacing traditional manual measurement methods.

[0003] However, existing automated tunnel monitoring technologies still have limitations in practical engineering applications. Firstly, the stability of the monitoring benchmark is difficult to guarantee. At tunnel construction sites, automated monitoring equipment is typically installed on the sidewalls or secondary lining trolleys near the tunnel face. This area is susceptible to the effects of blasting vibrations, heavy machinery operations, and the rheological properties of the surrounding rock itself, making the monitoring station foundation prone to minute displacements or attitude deviations. Due to the lack of a real-time absolute spatial benchmark verification mechanism, the rigid body displacement of the monitoring station itself is often incorrectly included in the monitoring data, leading to distorted deformation measurement results that fail to accurately reflect the convergence state of the surrounding rock.

[0004] Secondly, the coupling problem between deep rock deformation and support structure deformation has not been effectively solved. Current technologies often use observation points directly attached or shallowly buried on the surface of the initial support for measurement. The data obtained in this way is actually a superposition of deep rock compression deformation, initial support shotcrete shrinkage and creep, and overall settlement of the steel arch. Due to the lack of a physical isolation mechanism, it is difficult to decouple and distinguish the actual displacement of the deep rock from the deformation of the support surface, making it difficult to accurately determine the development range of the loosened zone and the stability trend of the deep rock mass.

[0005] Furthermore, tunnel construction environments are characterized by high dust levels, high humidity, and harsh lighting conditions. Existing visual monitoring solutions often struggle to simultaneously meet the requirements of high precision in point displacement measurement and full coverage of cross-sectional profile measurement. Relying solely on passive vision is susceptible to interference from stray light, while active vision solutions often suffer from overexposure or feature loss due to insufficient dynamic range when facing highly reflective targets and diffusely reflective lining surfaces. This makes it difficult to achieve synchronous, high signal-to-noise ratio acquisition of key rock displacement points and support structure profiles within the same monitoring system. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides an automated monitoring system for the deformation of surrounding rock and initial support in tunnels during the construction period. This system solves the problems of unreliable measurement data due to the susceptibility of the station benchmark to interference in the dynamic environment of tunnel construction, the difficulty in physically isolating and decoupling deep surrounding rock deformation and initial support structure displacement, and the difficulty in synchronously and accurately acquiring the displacement of key points in the surrounding rock and the surface contour of the support structure under complex lighting conditions.

[0007] To achieve the above objectives, the present invention provides the following technical solution: This invention provides an automated monitoring system for the deformation of surrounding rock and initial support in tunnels during the construction period. The automated monitoring system is deployed at the tunnel construction site, with its layout space divided longitudinally into a stable zone and an initial support zone. The stable zone is located behind the tunnel face where the surrounding rock deformation tends to converge or the secondary lining structure is completed, while the initial support zone is located near the tunnel face where excavation and support are underway.

[0008] The spatial layout of the automated monitoring system is characterized by separating the measurement base station from the measurement object. An image acquisition and analysis unit, a ground reference unit, and a primary support deformation monitoring and auxiliary lighting unit are set up within the stable area, while a surrounding rock deformation monitoring unit is set up within the primary support area. The monitoring field of view of the image acquisition and analysis unit covers the primary support area, enabling simultaneous observation of the measured target in the primary support area and the reference target in the stable area within the same field of view. The ground reference unit consists of ground targets fixed in the stable area, providing a static spatial position reference.

[0009] The surrounding rock deformation monitoring unit consists of reflective targets distributed across the cross-section of the initial support area. The initial support deformation monitoring and auxiliary lighting unit includes a structured light emitter and an auxiliary lighting device. The structured light emitter is used to project a measurement beam onto the inner contour surface of the initial support in the initial support area, and the auxiliary lighting device is used to project an illumination beam onto the location of the reflective targets.

[0010] For monitoring deep deformation of the surrounding rock, the reflective target employs a deep-hole anchoring and isolation force transmission structure. The reflective target includes an anchoring component, a force transmission rod, and a reflective component. The anchoring component is inserted into a deep hole inside the surrounding rock mass and establishes a rigid connection with the deep surrounding rock mass. One end of the force transmission rod is connected to the anchoring component, and the other end extends radially through the initial support layer into the tunnel cavity.

[0011] A protective sleeve is coaxially fitted around the outside of the force-transmitting connecting rod. This sleeve is pre-embedded in the initial support layer, and its inner diameter is larger than the outer diameter of the force-transmitting connecting rod. This structure maintains a non-bonded isolation between the force-transmitting connecting rod and the initial support layer. The force-transmitting connecting rod can freely extend, retract, or slide within the protective sleeve, thus shielding the rod from interference from the deformation of the initial support layer and ensuring that the reflective component only reflects the displacement of the deep surrounding rock. The reflective component is installed at the end of the force-transmitting connecting rod, and its integrated standard measurement interface can be adapted to a total station prism or reflector for easy manual verification.

[0012] For monitoring the deformation of the initial support surface, the structured light emitter uses a laser projection module to generate a fan-shaped light plane. The normal direction of this fan-shaped light plane is parallel to the tunnel axis, and the light plane intersects with the inner contour of the three-dimensional curved surface of the initial support, forming laser stripes on the support surface that reflect the shape of the cross-section contour. To improve the signal-to-noise ratio under complex lighting conditions, the structured light emitter emits a narrowband laser, and a narrowband filter with a matching transmission band is installed in front of the optical acquisition lens of the image acquisition and analysis unit to physically filter out stray light from the construction environment.

[0013] In terms of data acquisition and processing logic, the image acquisition and analysis unit includes an imaging acquisition component, a support and adjustment platform, and a computing and processing module. The imaging acquisition component is anchored to the bedrock or secondary lining structure in a stable area. The computing and processing module executes a time-division multiplexing acquisition strategy: within a single measurement cycle, the auxiliary lighting device and the structured light emitter are alternately activated through timing control to acquire a first frame image containing the characteristics of a bright reflective target and a second frame image containing the characteristics of laser stripes, respectively, thus solving the problem of dynamic range mismatch between bright targets and diffuse reflection light stripes under the same exposure parameters.

[0014] To eliminate displacement errors inherent to the station itself, the computational processing module utilizes ground reference units for real-time pose calibration. During acquisition, the module identifies ground target feature points located near the field of view and analyzes their pixel coordinate changes. Based on the principle of photogrammetric spatial resection, the real-time position coordinates and attitude angles of the imaging acquisition component in the absolute coordinate system are calculated. Subsequently, the system constructs a rigid body transformation matrix to uniformly transform the acquired reflective target coordinates and laser stripe point cloud data into the absolute coordinate system, eliminating rigid body displacement components caused by vibration or minor trolley movements.

[0015] Furthermore, for long-distance tunnel monitoring, multiple image acquisition and analysis units can be arranged at intervals along the longitudinal direction of the tunnel. An overlapping area is set between the fields of view of two adjacent units, and reflective targets or specially designed transfer station targets within the overlapping area are used as common connection points to achieve cascaded transformation and unification of coordinate systems of multiple stations.

[0016] This invention provides an automated monitoring system for the deformation of surrounding rock and initial support in tunnels during the construction phase. It offers the following advantages: 1. This invention adopts a spatial partitioning layout in which the image acquisition and analysis unit is placed in a stable area and the monitoring object is placed in the initial support area. It is combined with a ground reference unit arranged in the stable area. By acquiring the image data of the ground reference unit in real time and performing spatial resection calculation, the system can correct the station displacement and attitude changes caused by the micro-movement of the secondary lining trolley, bedrock vibration or thermal expansion and contraction in real time, thus ensuring the coordinate accuracy of the monitoring data in a dynamic construction environment.

[0017] 2. The reflective target in the surrounding rock deformation monitoring unit adopts an isolation structure of force transmission rod and protective sleeve. The protective sleeve shields the tangential bonding force and friction force generated by the initial support layer shrinkage or displacement on the internal force transmission rod, ensuring that the force transmission rod only transmits the displacement of the deep surrounding rock at the anchor end. This effectively distinguishes between the deep loosening of the surrounding rock and the deformation of the support structure itself, providing a real physical and mechanical basis for the tunnel stability evaluation.

[0018] 3. The system integrates a structured light emitter and an auxiliary lighting device. Combined with narrowband filtering technology and time-division multiplexing acquisition strategy, it physically filters out stray light from the construction background and matches the best exposure parameters for high-brightness reflective targets and diffuse reflection laser stripes respectively. The system can simultaneously acquire high signal-to-noise ratio initial support section contour data and surrounding rock point displacement data within a single monitoring field of view, realizing synchronous monitoring of point and surface. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the overall spatial layout of the automated monitoring system for the deformation of the surrounding rock and initial support of the tunnel during the construction period, according to an embodiment of the present invention. Detailed Implementation

[0020] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] See attached document Figure 1 The present invention provides an automated monitoring system for the deformation of the surrounding rock and initial support of a tunnel during the construction period. The automated monitoring system is arranged in the longitudinal extension space of the tunnel construction site.

[0022] The automated monitoring system includes a surrounding rock deformation monitoring unit, an initial support deformation monitoring and auxiliary lighting unit, an image acquisition and analysis unit, and a ground reference unit.

[0023] Based on the tunnel construction sequence and the stability of the surrounding rock, the space for the automated monitoring system is divided longitudinally into a stable zone and a primary support zone. The stable zone is located behind the tunnel face and belongs to the section where the secondary lining structure has been completed or the surrounding rock deformation is approaching convergence. The primary support zone is located in front of the tunnel face and belongs to the section where excavation and support construction are underway and the surrounding rock deformation is active.

[0024] The image acquisition and analysis unit is fixed within a stable area. Specifically, the image acquisition and analysis unit is fixedly mounted on the tunnel sidewall, arch, or secondary lining trolley within the stable area using brackets, and its installation location has a stable structural foundation. The image acquisition and analysis unit includes an optical acquisition lens, the optical axis of which points towards the primary support area, forming a monitoring field of view covering the primary support area.

[0025] The ground reference unit is arranged within a stable region. Each ground reference unit consists of several ground targets, which are fixedly installed on the tunnel floor, sidewalls, or the already formed secondary lining surface within the stable region. All ground targets are located within the monitoring field of view of the image acquisition and analysis unit, providing a static spatial coordinate reference.

[0026] The surrounding rock deformation monitoring unit is deployed on the tunnel cross-section in the initial support area. Each unit consists of several reflective targets. These targets are spaced apart along the tunnel cross-section contour and located deep within the surrounding rock at the tunnel arch, arch waist, and sidewalls. Each reflective target is within the monitoring field of view of the image acquisition and analysis unit.

[0027] The execution components of the initial support deformation monitoring and auxiliary lighting unit are arranged in a stable area. This unit includes a structured light emitter and an auxiliary lighting device. The structured light emitter is fixedly installed in the stable area (e.g., on the tunnel sidewall, arch waist, or secondary lining trolley) and located adjacent to the image acquisition and analysis unit. The projection window of the structured light emitter faces the inner contour surface of the initial support at the same cross-section, projecting visible laser stripes onto the initial support surface.

[0028] The auxiliary lighting device is positioned in the stable region or the initial support region, and its illumination direction is directed towards the location of the reflective target in the initial support region. In this embodiment, the auxiliary lighting device is arranged adjacent to the image acquisition and analysis unit in the stable region, and projects an illumination beam forward to stimulate the reflective properties of the reflective target.

[0029] Through the above spatial layout, the image acquisition and analysis unit can simultaneously acquire the laser stripe image projected onto the primary support surface by the structured light emitter, as well as the reflected light spot image formed by the reflective target under the illumination of the auxiliary lighting device, and simultaneously acquire the image information of the ground target within a unified monitoring field of view.

[0030] See attached document Figure 1 The surrounding rock deformation monitoring unit consists of multiple reflective targets distributed on the same monitoring section. The reflective targets are installed inside the tunnel surrounding rock by deep burial through boreholes. Each reflective target physically includes an anchoring component, a force transmission link, and a reflective component.

[0031] The anchoring component is located at the end of the reflective target and is inserted into a pre-drilled deep hole in the surrounding rock mass. The anchoring component establishes a rigid connection with the deep surrounding rock mass through grouting or mechanical anchoring at a specific depth inside or outside the loosened zone of the surrounding rock along the tunnel excavation outline.

[0032] One end of the force-transmitting link is fixedly connected to the anchoring assembly, and the other end extends radially toward the tunnel interior. The length of the force-transmitting link is greater than the thickness of the initial support layer of the tunnel. The force-transmitting link passes through the initial support layer (including shotcrete, steel arch, or steel mesh), and the link body remains unbonded or isolated from the initial support layer to ensure that the displacement of the force-transmitting link is independent of the surface displacement of the initial support layer, transmitting only the deformation of the deep surrounding rock.

[0033] To achieve the aforementioned isolation, a flexible isolation sleeve or a rigid protective sleeve is coaxially fitted around the outside of the force transmission link. The inner diameter of the protective sleeve is larger than the outer diameter of the force transmission link, and the space between them is filled with flexible grease or has a gap. The protective sleeve is pre-embedded in the initial support layer, allowing the force transmission link to freely expand, contract, or slide inside the protective sleeve, thereby shielding the force transmission link from the tangential friction or adhesive forces generated by the contraction or misalignment of the initial support layer.

[0034] The reflector assembly is fixedly mounted on the end of the force transmission link exposed within the tunnel cavity. The reflector assembly includes a support base and an optical reflector mounted on the support base. The optical reflector has directional retroreflective properties, and its surface is coated with a microprism array or a high-refractive-index glass microsphere coating. This optical reflector is configured to receive incident light and reflect it back along its original path or at a specific angle to the optical acquisition lens of the image acquisition and analysis unit.

[0035] In one specific implementation, the reflective target is constructed as a unidirectional reflective target. This type of optical reflector has a single principal reflective plane. An angle adjustment mechanism is provided between the support base and the force transmission link. This mechanism is used to adjust the normal direction of the principal reflective plane so that it points towards the image acquisition and analysis unit within the stable region.

[0036] In another specific implementation, the reflective target is constructed as a multi-directional reflective target. This type of optical reflector has a multifaceted prism structure or a spherical structure. The multifaceted prism structure contains multiple reflective surfaces facing different spatial quadrants, while the spherical structure has its surface omnidirectionally covered with reflective material. This structure allows the reflective target to reflect incident light from multiple different positions, supporting observation from different angles by multiple image acquisition devices.

[0037] The reflective assembly's support base also integrates a standard measurement interface. The mechanical dimensions of this standard measurement interface match the mounting interface of the total station prism or total station reflector. During the operation of the automated monitoring system, operators can temporarily mount the total station prism onto the standard measurement interface and use the total station to manually verify the spatial position of the reflective target, achieving a direct comparison between automated monitoring data and manual measurement data.

[0038] See attached document Figure 1 The initial support deformation monitoring and auxiliary lighting unit consists of a structured light emitter located in the stable region and an auxiliary lighting device located in the stable region or the initial support region. These two components work independently or collaboratively in terms of electrical connection, but functionally they work together to enhance the visual features of the section under test.

[0039] A structured light emitter is one or more laser projection modules. It is rigidly mounted on a stable bedrock, secondary lining structure surface, or independent support in a stable area, maintaining a relatively fixed spatial position relative to the image acquisition and analysis unit. The structured light emitter includes a laser diode light source, a heat dissipation base, and a linear optical lens group (such as a cylindrical mirror or a Powell prism). When powered on, the laser diode light source generates a high-brightness monochromatic continuous beam. This beam is shaped by the linear optical lens group and expanded into a fan-shaped light plane with a preset fan angle.

[0040] The structured light emitter is mounted such that the normal direction of the fan-shaped light plane is approximately parallel to the tunnel axis, and this fan-shaped light plane intersects the inner surface of the initial support. Due to the three-dimensional curved surface characteristics of the initial support, the fan-shaped light plane intercepts a continuous laser stripe on the initial support surface, which varies with the surface undulations. Under the diffuse reflection characteristics of the initial support surface, this laser stripe forms a high-contrast light band that can be captured by a remote imaging device. The geometry of this light band directly characterizes the real-time inner contour shape of the initial support section.

[0041] To improve the signal-to-noise ratio in the complex lighting environment of tunnels, the laser wavelength emitted by the structured light emitter is selected to be a specific narrowband band (e.g., 635nm red light or 808nm near-infrared light). Correspondingly, a narrowband filter matching this band is installed in front of the optical lens of the image acquisition and analysis unit. This narrowband filter only allows light of the corresponding band from the structured light emitter and auxiliary lighting devices to pass through (e.g., the auxiliary lighting devices also emit monochromatic light with the same wavelength as the structured light, or their spectral energy is concentrated to cover this narrowband band), physically filtering out background stray light generated by other construction lighting sources within the tunnel. Furthermore, the structured light emitter supports pulse modulation mode, enabling microsecond-level synchronization with the camera's exposure shutter, activating the laser only at the moment of camera exposure, further reducing heat accumulation and power consumption.

[0042] The structured light emitter's housing adopts a dustproof and waterproof industrial protective structure, and integrates a constant current drive circuit inside to maintain the stability of the output laser power and prevent the light strip brightness from flickering due to voltage fluctuations at the tunnel construction site.

[0043] The auxiliary lighting device is a high-power area array illuminator or spotlight illuminator. In Figure 1 In the illustrated embodiment, the auxiliary illumination device is positioned in a stable area and installed adjacent to the image acquisition and analysis unit. The auxiliary illumination device includes an array of light-emitting elements (such as an LED array) and beam-shaping optics. The light-emitting element array emits a spectral range covering the visible or near-infrared bands and is matched to the optical response characteristics of the reflective target.

[0044] A beam-shaping optical element is positioned at the front end of the light-emitting element array to confine the diverging light within a specific projection cone angle. This projection cone angle covers the spatial distribution area of ​​all reflective targets within the initial support region, ensuring that light energy is concentrated on the monitored object and reducing ineffective illumination of other non-measuring areas of the tunnel wall. When the auxiliary lighting device is activated, its emitted illumination beam illuminates the distant reflective target. Utilizing the retroreflective properties of the reflective target, the incident light returns along its original optical path, thus forming a high-brightness feature spot in the background of the image acquisition end's field of view. The brightness of this feature spot is higher than the brightness of the surrounding ambient light.

[0045] See attached document Figure 1 The image acquisition and analysis unit consists of an imaging acquisition component located in a stable area, a support and adjustment platform, and a computing and processing module. The imaging acquisition component is rigidly anchored to the stable bedrock of the tunnel lining structure, sidewalls, or floor slab via the support and adjustment platform, ensuring that the spatial position of the monitoring base station remains relatively constant.

[0046] The imaging acquisition unit comprises one or more high-resolution industrial vision sensors. Each vision sensor is equipped with a photosensitive chip (such as a CCD or CMOS sensor) sensitive to specific wavelengths of light and fitted with a fixed-focus optical lens. The focal length and aperture parameters of the optical lens are designed to match the monitoring distance from the stable region to the initial support region, ensuring that its field of view completely covers all reflective targets and laser stripes projected by the structured light emitter within the initial support region, while also covering the ground reference unit within the stable region. The depth of field of the optical lens covers the spatial depth from the nearest ground target to the farthest reflective target, ensuring that targets at different object distances can form clear real images on the photosensitive chip.

[0047] Considering the high dust environment during tunnel construction, the protective housing of the imaging acquisition component also integrates an air knife cleaning device or a mechanical wiper device at its front end. The air knife cleaning device is connected to a high-pressure air source on site, and continuously blows away adhering dust or water mist by forming a high-speed air curtain on the lens protective glass surface, maintaining the cleanliness of the optical window.

[0048] The computational processing module is connected to the imaging acquisition component via a high-speed wired or wireless data transmission link. This module integrates image processing and photogrammetric algorithms to perform tasks such as image acquisition control, feature extraction (including light stripe center extraction and spot centroid localization), and 3D spatial coordinate calculation.

[0049] To eliminate station displacement errors caused by tunnel construction vibrations, air disturbances, or minor deformations of the support structure, the system configures ground reference units within the field of view of the stable region. Each ground reference unit consists of at least three spatially fixed ground targets, which serve as control points for the absolute coordinate system. During each measurement cycle, the imaging acquisition component synchronously acquires image information from the ground targets. The computational processing module analyzes the pixel coordinate changes of the ground targets in the images and uses the principle of spatial resection to calculate the six-degree-of-freedom position and attitude parameters of the imaging acquisition component in the absolute coordinate system at the current moment. These parameters are then used to perform rigid body transformation correction on the measurement data in the initial support region, thereby eliminating displacement interference from the station itself.

[0050] For long tunnels where the monitoring distance exceeds the depth of field or field of view coverage of a single camera, the image acquisition and analysis unit is constructed as a multi-station cascaded network. In this network, multiple imaging acquisition units are arranged at intervals along the tunnel's longitudinal direction, with overlapping areas between the fields of view of adjacent imaging acquisition units. Reflective targets or specially designed transfer station targets located within this overlapping area are defined as common connection points. By identifying the coordinates of these common connection points in the fields of view of different stations, the system establishes a transformation matrix between the coordinate systems of adjacent stations, uniformly transforming the segmented acquisition of surrounding rock and initial support deformation data into the global engineering coordinate system, thus achieving continuous monitoring of long-distance tunnels.

[0051] See attached document Figure 1 The operation process and measurement principle of the system of this invention are based on the collaborative working mechanism of computer vision and photogrammetry. When the system is in working state, the computing and processing module of the image acquisition and analysis unit acts as the main control center, controlling the opening and closing of the auxiliary lighting device and the structured light emitter according to the preset timing logic, and simultaneously triggering the imaging acquisition component to perform image exposure.

[0052] Specifically, the preset timing logic employs a time-division multiplexing acquisition strategy. Within a single measurement cycle, the computational processing module first sends a first trigger signal to activate the auxiliary illumination device and deactivate the structured light emitter, controlling the imaging acquisition component to acquire a first frame image with low gain or short exposure time, specifically for extracting high-brightness reflective target features. Subsequently, a second trigger signal is sent to deactivate the auxiliary illumination device and activate the structured light emitter, controlling the imaging acquisition component to acquire a second frame image with high gain or long exposure time, specifically for extracting diffuse reflection structured light stripe features. The computational processing module fuses the target coordinate data from the first frame image with the light stripe contour data from the second frame image at the same timestamp, thereby preventing high-brightness targets from producing halos covering laser stripes under long exposures and solving the problem of insufficient dynamic range.

[0053] During the surrounding rock deformation measurement phase, the system executes a point displacement tracking process. The control command first triggers the auxiliary lighting device to activate, projecting an illumination beam onto the initial support area. Upon receiving the illumination beam, the reflective targets deeply embedded within the surrounding rock utilize the retroreflective properties of their optical elements to concentrate and reflect the light energy back to the stable region along the original optical path. At this time, non-cooperative targets in the environment (such as rock walls and mechanical equipment) appear as a dark background, while the reflective targets are imaged as clusters of high grayscale pixels on the photosensitive surface of the image sensor. The computational processing module performs binarization thresholding and connected component analysis on the acquired images to identify the light spot regions corresponding to each reflective target. Subsequently, a sub-pixel grayscale weighted centroid algorithm is used to extract the precise center coordinates of each light spot. Based on the pre-calibrated camera intrinsic parameter matrix (including focal length, principal point coordinates, and distortion coefficients) and the spatial positional relationships of each reflective target at the initial moment, the system, according to the number of sensors configured in the imaging acquisition component, selects either a perspective N-point localization algorithm based on monocular vision or a forward intersection algorithm based on binocular / multi-view stereo vision to calculate the three-dimensional spatial coordinates of each reflective target at the current moment. By calculating the difference vector between the current coordinates and the initial coordinates, the specific displacement of the deep surrounding rock in the directions of crown subsidence and peripheral convergence can be obtained.

[0054] During the initial support deformation measurement phase, the system executes a surface profile reconstruction process. Control commands trigger the activation of the structured light emitter located in the stable region. The fan-shaped laser plane projected by the structured light emitter truncates the inner surface of the initial support, forming laser stripes that curve with the surface geometry. Since there is a calibrated relative positional relationship (i.e., triangulation baseline) between the optical center of the image acquisition and analysis unit and the projection center of the structured light emitter, according to the principle of triangulation, the depth change of the initial support surface is directly mapped to the lateral offset of the laser stripes in the image. After the imaging acquisition component captures an image containing the laser stripes, the computational processing module uses the Stieg algorithm or the centroid method to extract the sub-pixel coordinate sequence of the light stripe center along the stripe normal direction. Combining the spatial equation of the structured light plane with the camera's perspective projection model, the system backprojects the two-dimensional light stripe coordinates on the image into three-dimensional space, reconstructing the profile curve of the initial support section covered by the laser stripes. By comparing the profile curve data at different time periods, the system quantitatively analyzes the overall deformation trend and local abrupt change characteristics of the initial support structure.

[0055] To ensure the spatial reference consistency of the two types of measurement data, the system synchronously executes a station pose self-calibration process during each acquisition operation. Simultaneously with acquiring images of the initial support area, or within the same measurement sequence, the imaging acquisition component captures images of ground targets within the stable area. Since the ground targets are physically anchored to immovable bedrock, their absolute geodetic coordinates are known and constant. The computational processing module identifies feature points of the ground targets in the images and uses the principle of spatial resection to calculate the real-time position coordinates of the optical center of the imaging acquisition component in the absolute coordinate system. and three-axis attitude angles The system uses the real-time pose parameters to construct a rigid body transformation matrix, and performs rigid body transformation correction on the coordinate data of the surrounding rock reflective target and the light stripe point cloud data of the initial support. This eliminates rigid body displacement errors caused by vibration of the measuring station support, thermal expansion and contraction, or micro-movement of the secondary lining trolley, ensuring that the output deformation only includes the actual physical deformation of the measured object.

[0056] Based on the above process, this system achieves synchronous monitoring of deep rock deformation and initial support surface deformation. The reflective target and structured light stripes are located on the same monitoring section, and image acquisition occurs at the same time or within a very short time window, enabling the system to construct a rock-support interaction data model with strict temporal synchronization and spatial correspondence. Furthermore, when verifying the accuracy of the automated monitoring data, operators install a total station prism on the standard interface reserved on the reflective target and independently determine the spatial coordinates of the point using the total station. The system compares the total station measurement results with the automated visual measurement results from the same time period. If the deviation is within the allowable range, the system is confirmed to be operating normally; if a systematic deviation exists, the system's calculation parameters are corrected and updated using manual measurement data.

Claims

1. An automated monitoring system for deformation of surrounding rock and initial support during tunnel construction, characterized in that, This includes an integrated monitoring station deployed in the longitudinal stability zone of the tunnel and cooperative target components deployed in the initial support zone; The integrated monitoring station includes an image acquisition and analysis unit, a ground reference unit located within the field of view of the image acquisition and analysis unit, and an initial support deformation monitoring and auxiliary lighting unit. The cooperative target component includes reflective targets for monitoring surrounding rock deformation distributed across the cross section of the initial support area; The monitoring field of view of the image acquisition and analysis unit covers the cooperative target component; The initial support deformation monitoring and auxiliary lighting unit is configured to project a light plane onto the inner contour of the initial support through a structured light emitter, and to project a light beam through an auxiliary lighting device to illuminate the reflective target for imaging by the image acquisition and analysis unit.

2. The automated monitoring system for deformation of surrounding rock and initial support during tunnel construction as described in claim 1, characterized in that, The reflective target includes an anchoring assembly, a force transmission link, and a reflective assembly. The anchoring component is inserted into a deep hole inside the surrounding rock mass and connected to the surrounding rock mass. One end of the force transmission link is connected to the anchoring assembly, and the other end extends radially toward the tunnel interior and passes through the initial support layer. The force transmission link body and the initial support layer are kept in a non-bonded and isolated state; The reflective component is installed at the end of the force transmission link that is exposed inside the tunnel.

3. The automated monitoring system for deformation of surrounding rock and initial support during tunnel construction as described in claim 2, characterized in that, The force transmission link is coaxially fitted with a protective sleeve. The inner diameter of the protective sleeve is larger than the outer diameter of the force transmission link. The protective sleeve is embedded in the initial support layer. The force transmission link extends, contracts or slides inside the protective sleeve.

4. The automated monitoring system for deformation of surrounding rock and initial support during tunnel construction as described in claim 2, characterized in that, The reflective assembly includes a support base and an optical reflector disposed on the support base; The support base integrates a standard measurement interface, the mechanical dimensions of which are matched to the mounting interface of the total station prism or total station reflector.

5. The automated monitoring system for deformation of surrounding rock and initial support during tunnel construction as described in claim 1, characterized in that, The structured light emitter includes a laser projection module; The laser projection module generates a fan-shaped light plane, the normal direction of which is parallel to the tunnel axis, and the fan-shaped light plane intersects with the inner contour surface of the initial support to form laser stripes.

6. The automated monitoring system for deformation of surrounding rock and initial support during tunnel construction as described in claim 5, characterized in that, The structured light emitter emits a narrowband laser, and the spectral band emitted by the auxiliary lighting device covers the wavelength range of the narrowband laser. A narrowband filter is installed in front of the optical acquisition lens of the image acquisition and analysis unit. The transmission band of the narrowband filter matches the transmission band of the structured light emitter and the auxiliary lighting device.

7. The automated monitoring system for deformation of surrounding rock and initial support during tunnel construction as described in claim 1, characterized in that, The image acquisition and analysis unit includes an imaging acquisition component, a support and adjustment platform, and a computing and processing module; The imaging acquisition component is anchored to the bedrock or secondary lining structure of the stable area via the support and adjustment platform. The imaging acquisition component is connected to the computing and processing module.

8. The automated monitoring system for deformation of surrounding rock and initial support during tunnel construction as described in claim 7, characterized in that, The computation processing module is configured to execute a time-division multiplexing acquisition strategy; Within a single measurement cycle, the computational processing module first turns on the auxiliary lighting device and turns off the structured light emitter to acquire the first frame image, then turns off the auxiliary lighting device and turns on the structured light emitter to acquire the second frame image.

9. An automated monitoring system for deformation of surrounding rock and initial support during tunnel construction, as described in claim 7, is characterized in that, The computational processing module is configured to identify the feature points of the ground target. The calculation and processing module analyzes the changes in the pixel coordinates of the ground target, calculates the position coordinates and attitude angles of the imaging acquisition component in the absolute coordinate system, and constructs a rigid body transformation matrix to correct the reflective target and laser stripe data.

10. An automated monitoring system for deformation of surrounding rock and initial support during tunnel construction, as described in claim 1, is characterized in that... The image acquisition and analysis unit is arranged in multiple sets at intervals along the longitudinal direction of the tunnel; An overlapping area is provided between the fields of view of two adjacent groups of image acquisition and analysis units, and a reflective target or transfer target is provided in the overlapping area as a common connection point.

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