Drilling and blasting tunnel advance stratum wireless monitoring and stress release coefficient inversion method
By combining a wireless flexible displacement surveying system with advanced small guide pipes in drill-and-blast tunnels, the stress release coefficient can be monitored and calculated in real time. This solves the problems of inaccurate calculation and non-real-time monitoring of the stress release coefficient in drill-and-blast tunnels, and achieves high-precision stress release coefficient inversion.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- STATE GRID SHANGHAI MUNICIPAL ELECTRIC POWER CO
- Filing Date
- 2026-04-07
- Publication Date
- 2026-07-03
AI Technical Summary
Existing technologies lack precise methods for calculating stress release coefficients in drill-and-blast tunnels. Traditional monitoring methods are affected by blasting operations and equipment obstruction, making it impossible to achieve real-time monitoring of unexcavated strata. Furthermore, WSS equipment is inconvenient to install and has low positioning accuracy, making it difficult to meet the needs of advanced strata monitoring.
A wireless flexible displacement surveying system (WSS) combined with advanced small guide pipes is used to monitor the settlement value of the unexcavated strata 0.7-3.7m in front of the tunnel face in real time. A precise calculation method for the stress release coefficient is established through numerical modeling and softening modulus method. The WSS system is improved to adapt to the drill-and-blast tunnel environment and achieve recycling.
It enables real-time monitoring of unexcavated strata, improves the calculation accuracy of stress release coefficient, adapts to the construction environment of drill-and-blast tunnels, and ensures the positioning accuracy and reusability of monitoring equipment.
Smart Images
Figure CN122333596A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of tunnel and underground engineering disaster monitoring technology, specifically involving a method for wireless monitoring of strata ahead of drilling and blasting tunnels and inversion of stress release coefficients. Background Technology
[0002] In drill-and-blast tunnel excavation, accurately determining the stress release coefficient of the surrounding rock is a key technical challenge in tunnel engineering design and construction. The stress release coefficient directly determines the design parameters and construction timing of the support structure, and its accuracy is crucial to the long-term stability of the tunnel structure. If the stress release coefficient is estimated too low, the support structure design will be overly conservative, resulting in project waste; if it is estimated too high, it may lead to support structure failure, causing minor issues such as excessive tunnel deformation and lining cracking, or even major safety accidents such as tunnel collapse.
[0003] However, existing technologies have the following shortcomings: they mainly rely on empirical values and simple numerical inversion, lacking precise calculation methods based on measured data, making it difficult to guarantee the accuracy of the values; traditional monitoring methods are affected by blasting operations and large machinery obstruction, and can only perform low-frequency deformation monitoring of the excavated section once every 1 to 2 days, failing to capture the stress release process of the unexcavated strata in front of the tunnel face; existing WSS equipment is not optimized for the complex environment of drill-and-blast tunnels, and has problems such as inconvenient installation, low positioning accuracy, and difficulty in recycling and reuse, failing to meet the needs of real-time monitoring of advanced strata.
[0004] Therefore, a new method is urgently needed. Summary of the Invention
[0005] The purpose of this invention is to provide a method for advanced wireless monitoring of the strata and inversion of stress release coefficient in drill-and-blast tunnels. This method relies on advanced small guide pipes to realize real-time monitoring of longitudinal settlement of the 0.7-3.7m unexcavated strata in front of the tunnel face under blasting conditions, filling the gap of traditional monitoring; improving the accuracy of stress release coefficient; and after improvements such as flexible hinges, the WSS can be adapted to the construction environment, ensure accuracy, and be recycled.
[0006] To achieve the above objectives, this invention provides a method for wireless monitoring of strata ahead of drilling and blasting tunnels and inversion of stress release coefficients, comprising the following steps: S1. Insert the wireless flexible displacement inclinometer system into the advance small guide pipe and fix it in place to measure the settlement value of the unexcavated strata in front of the tunnel face; S2. Use the wireless flexible displacement surveying system deployed in S1 to obtain tunnel structure design parameters and geological parameters at the construction site; S3. Based on the tunnel structure design parameters and construction site geological parameters in S2, a numerical model is built; S4. Set the stress release coefficient in the numerical model constructed in S3, use the softening modulus method to calculate the formation stress release process, extract the simulated settlement value of the corresponding measuring point, and establish a database of the correspondence between the coefficient and the settlement. S5. Based on the measured longitudinal settlement value in S1 as the benchmark data, the least squares method is called to compare the benchmark data with the simulated settlement value corresponding to the stress release coefficient in the correspondence library of S4 point by point, calculate the error between the simulated value and the measured value, and obtain the actual surrounding rock stress release coefficient.
[0007] Preferably, the wireless flexible displacement inclinometer system in S1 includes a single-section wireless flexible displacement inclinometer rod, which is connected sequentially via movable hinges to form a flexible deformation measurement body; a clamping sleeve is used to securely connect each single-section inclinometer rod; a data transmission antenna is connected to a microelectromechanical system sensor on the single-section inclinometer rod, and the collected deformation data such as the inclination angle of the inclinometer rod is transmitted to the wireless intelligent gateway via the antenna, and then the gateway uploads the data.
[0008] Preferably, the formula for calculating the settlement difference between the two ends of the wireless flexible displacement inclinometer rod is as follows: ; Where 500 is the length of one section of the inclined plane rod. This is the initial tilt angle monitoring value. This is the tilt angle monitoring value.
[0009] Preferably, the measurement in S1 of the area in front of the working face specifically includes: The measurement range starts 0.7m in front of the tunnel face and is divided into 6 monitoring intervals at 0.5m intervals: 0.7m-1.2m, 1.2m-1.7m, 1.7m-2.2m, 2.2m-2.7m, 2.7m-3.2m, and 3.2m-3.7m.
[0010] Preferably, in S4, the softening modulus method is used, which replaces the original elastic modulus of the strata in the excavation area with an equivalent softening modulus. The formula for the proportion of the softening modulus is: ; Where λ is the stress relief coefficient; Equivalent softening modulus; This is the original elastic modulus.
[0011] This invention also provides a wireless monitoring system for advanced formations and a stress release coefficient inversion system for drill-and-blast tunnels, including: The data acquisition module is used to insert and fix the wireless flexible displacement inclinometer system into the advance small guide tube to measure the settlement value of the unexcavated strata in front of the tunnel face; The parameter collection module is connected to the data acquisition module and acquires tunnel structure design parameters and construction site geological parameters based on the wireless flexible displacement inclinometer system. The numerical model building module is connected to the parameter collection module and builds a numerical model based on the tunnel structure design parameters and the geological parameters of the construction site. The database module is connected to the numerical model construction module. Based on the stress release coefficient set in the numerical model, the softening modulus method is used to calculate the formation stress release process, extract the simulated settlement value of the corresponding measuring point, and establish a database of the correspondence between coefficients and settlement. The stress release coefficient inversion module is connected to the database module. Based on the measured longitudinal settlement value as the reference data, it calls the least squares method to compare the reference data with the simulated settlement value corresponding to the stress release coefficient in the corresponding relational database point by point, calculates the error between the simulated value and the measured value, and obtains the actual surrounding rock stress release coefficient.
[0012] Therefore, the present invention employs the above-mentioned method for advanced wireless monitoring of strata and stress release coefficient inversion in drill-and-blast tunnels. Compared with the prior art, the technical solution of the present invention has the following beneficial effects: (1) The present invention adopts an improved WSS system, relying on advanced small guide pipes as a protective structure to overcome the problems of being unable to monitor the deformation of the unexcavated strata in front of the tunnel face and poor monitoring timeliness, and realizes real-time monitoring of the longitudinal settlement of the unexcavated strata within 0.7-3.7m in front of the tunnel face under blasting conditions, filling the monitoring gap of traditional methods; (2) This invention establishes a calculation system of “measured data + numerical model”. Based on WSS high-precision data, it constructs a corresponding relation database by combining the softening modulus method. Through optimization algorithm inversion, it overcomes the problem of lack of accurate calculation methods based on measured data for stress release coefficient and improves the calculation accuracy of stress release coefficient. (3) The present invention makes targeted improvements to WSS by setting up a flexible hinge mechanism, an elastic fixed ring assembly, and a recovery traction device to overcome the problem that the existing WSS equipment cannot adapt to the special environment of drill-and-blast tunnels. This makes WSS adaptable to the installation path, ensures positioning accuracy, and enables recycling, thus adapting to the special construction environment of drill-and-blast tunnels.
[0013] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description
[0014] Figure 1 This is a flowchart illustrating an embodiment of the method for wireless monitoring of strata and inversion of stress release coefficients in drill-and-blast tunnels according to the present invention. Figure 2 This is a structural design diagram of a flexible inclinometer system according to an embodiment of the method for wireless monitoring of strata and inversion of stress release coefficient in drill-and-blast tunnels of the present invention. Figure 3 This is a schematic diagram of the longitudinal section of the unexcavated strata longitudinal settlement monitoring equipment in front of the tunnel face in an embodiment of the method for wireless monitoring of advanced strata and stress release coefficient inversion in drill-and-blast tunnels of the present invention. Figure 4 This is a schematic diagram of the softening modulus method in an embodiment of the method for wireless monitoring of strata ahead of drilling and blasting tunnels and inversion of stress release coefficients according to the present invention. Detailed Implementation
[0015] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of 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, not all embodiments. All other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Unless otherwise defined, the technical or scientific terms used in the present invention should have the ordinary meaning understood by those skilled in the art.
[0016] Example 1 like Figures 1-4 As shown, the method for wireless monitoring of strata and inversion of stress release coefficient in drill-and-blast tunnels according to the present invention includes the following steps: S1. Deploy and improve the wireless flexible displacement measurement system and collect advanced ground settlement data; In this step, such as Figure 2 As shown, a specially improved wireless flexible displacement inclinometer system (WSS) is adopted, and its core improvements and structural parameters are as follows: The longitudinal dimension is 3700mm, and it is functionally divided into a signal transmission section and a deformation measurement section. The signal transmission section is located at the front end of the system and consists of a 700mm long antenna module, which is specifically responsible for wireless data transmission. The deformation measurement section consists of six 500mm long standard measurement units arranged linearly, each with a 28mm diameter circular cross-section design. The inclination measurement units are connected by a flexible hinge mechanism, giving the WSS system flexible deformation capabilities in three-dimensional space. It can bend adaptively according to the installation path of the advanced small guide tube, facilitating equipment pushing and positioning. A matching elastic fixing ring assembly was developed, with an inner ring diameter of 28mm to fit tightly against the outer wall of the inclinometer rod; the outer ring diameter was customized according to the inner wall size of the advanced small conduit used on site, and the monitoring equipment was firmly embedded and accurately positioned in the pipeline through interference fit. A recovery traction device is integrated at the top of the WSS. After the data analysis task after the blasting is completed, the monitoring system can be easily removed from the advanced support pipeline through this device, so as to realize the recycling of equipment and cost control. Each measurement unit is equipped with a microelectromechanical system (MEMS) tilt sensor, which outputs tilt angle information relative to the horizontal plane along three orthogonal axes: X, Y, and Z. According to the measurement procedure, the change in X-axis angle serves as the basic data for longitudinal deformation calculation, while the monitored values of Y-axis and Z-axis angles are used to evaluate the spatial stability of the entire measurement system. The on-site deployment process is as follows: The WSS system was deployed on-site during the steel arch frame erection process in the tunnel construction cycle. During implementation, one pre-support pipe was reserved for monitoring without grouting. Before installation, the matching ring fasteners were installed on each inclination module one by one. Then, the assembled WSS system was pushed into the reserved monitoring pipe and positioned and locked. The data collection process is as follows: From the longitudinal profile of the tunnel, the 0.7m antenna section at the front end of the system does not participate in deformation monitoring; it is only responsible for communication. The effective measurement range starts 0.7m in front of the tunnel face and is evenly divided into 6 monitoring intervals at 0.5m intervals: 0.7-1.2m, 1.2-1.7m, 1.7-2.2m, 2.2-2.7m, 2.7-3.2m, and 3.2-3.7m. The settlement difference between the two ends of each section of the inclinometer rod is calculated using the following formula: ; Where 500 represents the length of one section of the inclined plane rod, in mm. This is the initial tilt angle monitoring value. This is the tilt angle monitoring value; Deformation data collected from each monitoring section is wirelessly transmitted via a front-end antenna module to an intelligent receiving terminal deployed at the tunnel entrance. This terminal needs to be deployed in an area with 4G network coverage. The effective distance of WSS wireless transmission is 900 meters. When the distance between the monitoring point and the receiving terminal exceeds this range, additional signal relay equipment needs to be configured to ensure data transmission quality. To improve the accuracy of subsequent stress release coefficient calculations, the WSS system should be deployed in as many advanced small guide pipes as possible in the tunnel cross section to obtain more comprehensive ground deformation data. S2. Use S1 to deploy the WSS system to collect tunnel structural design parameters, including tunnel cross-sectional shape, cross-sectional dimensions, support structure type and specific parameters, as well as geological parameters at the construction site, including surrounding rock grade, stratum mechanical parameters (elastic modulus, Poisson's ratio, internal friction angle, cohesion, etc.) and in-situ stress state (such as the magnitude and direction of initial in-situ stress). S3. Based on the tunnel structure design parameters and construction site geological parameters in S2, a three-dimensional numerical model of tunnel excavation matching the actual project is constructed using numerical simulation software. S4. In the three-dimensional numerical model constructed in S3, a series of stress release coefficients with different values are set; the softening modulus method is adopted, by replacing the original elastic modulus of the strata in the excavation area with an equivalent softening modulus. The proportional formula for the softening modulus is: ; in, This is the stress relief coefficient, with a value range of (0 ≤ ≤1); Equivalent softening modulus; The original elastic modulus of the formation; Through multiple iterative calculations and gradual adjustments The value of is used to simulate the formation stress release process under different stress release coefficients; S5. Based on the measured longitudinal settlement value in S1 as the benchmark data, the least squares method or other optimization algorithm is called to compare and analyze the benchmark data with the simulated settlement deformation value corresponding to each stress release coefficient in the S4 database point by point, calculate the error between the simulated value and the measured value, and select the numerical model with the smallest error; the stress release coefficient corresponding to the numerical model is the actual surrounding rock stress release coefficient.
[0017] Therefore, the present invention adopts the above-mentioned method of wireless monitoring of strata ahead of drilling and blasting tunnels and inversion of stress release coefficient. This method relies on advanced small guide pipes to realize real-time monitoring of longitudinal settlement of 0.7-3.7m unexcavated strata ahead of the tunnel face under blasting conditions, filling the gap of traditional monitoring; improving the accuracy of stress release coefficient; and after the WSS is improved with flexible hinges, it is adapted to the construction environment, ensures accuracy and can be recycled.
[0018] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.
Claims
1. A method for wireless monitoring of strata ahead of drilling and blasting tunnels and inversion of stress release coefficients, characterized in that, Includes the following steps: S1. Insert the wireless flexible displacement inclinometer system into the advance small guide pipe and fix it in place to measure the settlement value of the unexcavated strata in front of the tunnel face; S2. Use the wireless flexible displacement surveying system deployed in S1 to obtain tunnel structure design parameters and geological parameters at the construction site; S3. Based on the tunnel structure design parameters and construction site geological parameters in S2, a numerical model is built; S4. Set the stress release coefficient in the numerical model constructed in S3, use the softening modulus method to calculate the formation stress release process, extract the simulated settlement value of the corresponding measuring point, and establish a database of the correspondence between the coefficient and the settlement. S5. Based on the measured longitudinal settlement value in S1 as the benchmark data, the least squares method is called to compare the benchmark data with the simulated settlement value corresponding to the stress release coefficient in the correspondence library of S4 point by point, calculate the error between the simulated value and the measured value, and obtain the actual surrounding rock stress release coefficient.
2. The method for wireless monitoring of strata and inversion of stress release coefficient in drill-and-blast tunnels according to claim 1, characterized in that, The wireless flexible displacement inclinometer system in S1 includes a single-section wireless flexible displacement inclinometer rod, which is connected in sequence through movable hinges to form a flexible deformation measurement body. The clamping sleeve is used to securely connect each individual section of the inclinometer rod; the data transmission antenna is connected to the microelectromechanical system sensor on the individual section of the inclinometer rod, and the collected deformation data such as the inclination angle of the inclinometer rod is transmitted to the wireless intelligent gateway via the antenna, and then the gateway uploads the data.
3. The method for wireless monitoring of strata and inversion of stress release coefficient in drill-and-blast tunnels according to claim 2, characterized in that, The formula for calculating the settlement difference between the two ends of the wireless flexible displacement inclinometer rod is as follows: ； Where 500 is the length of one section of the inclined plane rod. This is the initial tilt angle monitoring value. This is the tilt angle monitoring value.
4. The method for wireless monitoring of strata and inversion of stress release coefficient in drill-and-blast tunnels according to claim 3, characterized in that, The specific measurement in S1 of the area in front of the working face is as follows: The measurement range begins 0.7m in front of the tunnel face and is divided into 6 monitoring zones at 0.5m intervals: 0.7m-1.2m, 1.2m-1.7m, 1.7m-2.2m, 2.2m-2.7m, 2.7m-3.2m, 3.2m-3.7m.
5. The method for wireless monitoring of strata and inversion of stress release coefficient in drill-and-blast tunnels according to claim 4, characterized in that, In S4, the softening modulus method is used, which replaces the original elastic modulus of the strata in the excavation area with an equivalent softening modulus. The formula for the proportion of the softening modulus is: ； Where λ is the stress relief coefficient; Equivalent softening modulus; This is the original elastic modulus.
6. A wireless monitoring and stress release coefficient inversion system for drill-and-blast tunnels, applied to the wireless monitoring and stress release coefficient inversion method for drill-and-blast tunnels as described in any one of claims 1-5, characterized in that, include: The data acquisition module is used to insert and fix the wireless flexible displacement inclinometer system into the advance small guide tube to measure the settlement value of the unexcavated strata in front of the tunnel face; The parameter collection module is connected to the data acquisition module and acquires tunnel structure design parameters and construction site geological parameters based on the wireless flexible displacement inclinometer system. The numerical model building module is connected to the parameter collection module and builds a numerical model based on the tunnel structure design parameters and the geological parameters of the construction site. The database module is connected to the numerical model construction module. Based on the stress release coefficient set in the numerical model, the softening modulus method is used to calculate the formation stress release process, extract the simulated settlement value of the corresponding measuring point, and establish a database of the correspondence between coefficients and settlement. The stress release coefficient inversion module is connected to the database module. Based on the measured longitudinal settlement value as the reference data, it calls the least squares method to compare the reference data with the simulated settlement value corresponding to the stress release coefficient in the corresponding relational database point by point, calculates the error between the simulated value and the measured value, and obtains the actual surrounding rock stress release coefficient.