A warning method for surrounding rock support of mined - out tunnel

Abstract

The present invention provides a warning method for the support of surrounding rock in a mined tunnel, which relates to the technical field of tunnel support detection. By dividing the ground penetrating radar into two types of sensors and placing them in the supported and unsupported sections respectively, the present invention can simultaneously obtain geological data under two different construction states, thereby establishing a benchmark comparison system. By extracting various characteristic indexes of the reflected wave, such as the peak arrival time, the maximum amplitude value, the total energy, and the main frequency and frequency bandwidth, the solution realizes comprehensive multi-parameter analysis, constructs a difference degree index and a stability uniformity index. These two new indexes provide a more forward-looking perspective for risk analysis. Combining with the risk analysis model can output a support risk index, making the identification of potential problems in the unsupported section more timely.

Description

Technical Field

[0001] The present invention relates to the technical field of tunnel support detection, and specifically provides a warning method for surrounding rock support of mined tunnels. Background Art

[0002] Tunnel surrounding rock refers to the rock or soil around the tunnel. In an unsupported tunnel, the side walls of the tunnel are all surrounding rock, so its properties and stability directly affect the safety of the tunnel. In the field of tunnel engineering, the construction safety of the side walls of an unsupported tunnel, that is, the surrounding rock, has always been a core issue of great concern. The risks in the unsupported tunnel section mainly include local collapse and falling of the surrounding rock part. With the large-scale advancement of infrastructure projects, how to improve the safety and efficiency of tunnel construction has become a key development direction in the industry. Currently, many advanced technologies are being combined with traditional tunnel construction methods to achieve more efficient risk management and construction control. This trend has promoted the technological upgrading of the industry and laid a foundation for realizing intelligent and precise construction.

[0003] In the prior art, ground penetrating radar has played an important role as a key detection tool. Ground penetrating radar can detect geological structures by emitting electromagnetic waves and obtain detailed information inside the tunnel. This technology can provide high-resolution data to help identify potential risks in the tunnel structure. However, current applications mostly focus on the monitoring of the supported sections and lack risk prediction for the unsupported sections.

[0004] The deficiencies of the prior art are mainly reflected in the limitations of data analysis and application. Although ground penetrating radar can provide rich data, its use in the risk assessment of unsupported tunnel sections is limited. Traditional methods often only focus on the analysis of a single data point and lack comprehensive analysis means of multiple parameters, and cannot flexibly use the information of the supported sections for risk prediction. This results in untimely identification of potential problems in the unsupported sections and affects the overall safety and efficiency of construction.

[0005] The above information disclosed in the background art section is only used to enhance the understanding of the background of the present disclosure, and thus it may include information that does not constitute the prior art known to those of ordinary skill in the art. Summary of the Invention

[0006] The purpose of the present invention is to provide a warning method for surrounding rock support of mined tunnels to solve the problems raised in the above background art.

[0007] To achieve the above purpose, the present invention provides the following technical solutions:

[0008] A warning method for surrounding rock support of mined tunnels, the specific steps include:

[0009] Step 1: Deploy geological radars on the walls and vaults on both sides of the tunnel section, and set the geological radars deployed in the tunnel section without support as the first type of sensor, and set the geological radars deployed in the tunnel section with support as the second type of sensor, and obtain the reflected wave data of all geological radars;

[0010] Step 2: According to the reflected wave data of each geological radar, obtain the peak arrival time and the maximum amplitude value of each reflected wave respectively, integrate each reflected wave data, calculate the total energy of each reflected wave, and calculate the average value of the peak arrival time, maximum amplitude value and total energy of the reflected wave data collected by the first type of sensor and the second type of sensor on the walls and the vault on both sides respectively;

[0011] Step 3: Analyze the average values ​​of the peak arrival time, maximum amplitude value and total energy of the first type of sensors and the second type of sensors on the walls and the vault on both sides, generate the offset degree data of the reflected wave collected by the second type of sensors relative to the reflected wave collected by the first type of sensors, and generate the difference degree index based on the offset degree data;

[0012] Step 4: Perform fast Fourier transform on the reflected wave data collected by the first type of sensor, convert the reflected wave data from the time domain to the frequency domain, obtain the main frequency data and frequency bandwidth data of the reflected wave data, and calculate the average values ​​of the main frequency data and frequency bandwidth data of the reflected wave data collected by the first type of sensor on the walls and the vault on both sides;

[0013] Step 5: Based on the average of the main frequency data and the frequency bandwidth data collected by the first type of sensors on the walls and the vault on both sides, and combined with the main frequency data and the frequency bandwidth data obtained by the first type of sensors, a stability uniformity index of the tunnel section without support is generated;

[0014] Step 6: Comprehensively analyze and process the difference degree index and the stability uniformity index, build a risk analysis model, obtain the support risk index of the unsupported tunnel section, compare the support risk index with the safety threshold, and determine whether to issue a risk warning.

[0015] Furthermore, a geological radar is arranged in the center of the vault, and the spacing between the geological radars at all vaults is the same, and the spacing is calibrated as k d All the geological radars arranged on the walls and vaults of the tunnel section are on the same horizontal plane, and the spacing between the geological radars on the walls is the same, and the spacing is calibrated as k c , and k c =1.5*k d .

[0016] Further, each ground penetrating radar starts to emit detection waves at the same time point and begins to record data. The moment when the detection waves start to be emitted is calibrated as the zero moment as a reference point. The frequencies and amplitudes of the detection waves emitted by all ground penetrating radars are the same. Each reflected wave signal is scanned along the time axis to find the maximum value of the signal intensity, and this signal intensity is calibrated as the maximum amplitude value of the reflected wave. The moment value corresponding to the maximum amplitude value is calibrated as the peak arrival time of the reflected wave. The formula for calculating the total energy of the reflected wave is:

[0017]

[0018] where E represents the total energy of the reflected wave, t max represents the peak arrival time of the reflected wave, s(t) represents the reflected wave data, and t represents the time variable.

[0019] Further, the specific logic for calculating the average values of the peak arrival time, maximum amplitude value, and total energy of the reflected wave data collected by the first type of sensors on both side walls and the vault is as follows:

[0020] Collect the maximum amplitude value, peak arrival time, and total energy of the reflected waves of the ground penetrating radars on both side walls of the tunnel section in the first type of sensors, and calculate the average value. The formula is:

[0021]

[0022] where sc1 max 、tc1 max and Ec1 respectively represent the average values of the maximum amplitude value, peak arrival time, and total energy of the reflected waves of the ground penetrating radars on both side walls of the tunnel section in the first type of sensors. N C1 represents the total number of the ground penetrating radars on both side walls of the tunnel section in the first type of sensors. sc1 i 、tc1 i and Ec1 i respectively represent the maximum amplitude value, peak arrival time, and total energy of the reflected waves of the i-th ground penetrating radar on both side walls of the tunnel section in the first type of sensors. i represents the number of the ground penetrating radars on both side walls of the tunnel section in the first type of sensors. i is a positive integer, and i = 1, 2,..., N C1 ;

[0023] Collect the maximum amplitude value, peak arrival time, and total energy of the reflected waves of the ground penetrating radars on the vault of the tunnel section in the first type of sensors, and calculate the average value. The formula is:

[0024]

[0025] where sd1 max, td1 max and Ed1 respectively represent the maximum amplitude value, peak arrival time, and average value of the total energy of the reflected wave of the ground penetrating radar located at the vault of the tunnel section in the first type of sensor. N d1 represents the total quantity of the ground penetrating radar located at the vault of the tunnel section in the first type of sensor, sd1 j , td1 j and Ed1 j respectively represent the maximum amplitude value, peak arrival time, and total energy of the reflected wave of the j-th ground penetrating radar located at the vault of the tunnel section in the first type of sensor. j represents the number of the ground penetrating radar located on both side walls of the tunnel section in the first type of sensor. j is a positive integer, and j = 1, 2,..., N d1 .

[0026] Furthermore, the specific logic for calculating the average value of the peak arrival time, maximum amplitude value, and total energy of the reflected wave data collected by the second type of sensor on both side walls and the vault is as follows:

[0027] Collect the maximum amplitude value, peak arrival time, and total energy of the reflected wave of the ground penetrating radar located on both side walls of the tunnel section in the second type of sensor, and calculate the average value. The formula is as follows:

[0028]

[0029] where, sc2 max , tc2 max and Ec2 respectively represent the maximum amplitude value, peak arrival time, and average value of the total energy of the reflected wave of the ground penetrating radar located on both side walls of the tunnel section in the second type of sensor. N C2 represents the total quantity of the ground penetrating radar located on both side walls of the tunnel section in the second type of sensor, sc2 m , tc2 m and Ec2 m respectively represent the maximum amplitude value, peak arrival time, and total energy of the reflected wave of the m-th ground penetrating radar located on both side walls of the tunnel section in the second type of sensor. m represents the number of the ground penetrating radar located on both side walls of the tunnel section in the second type of sensor. m is a positive integer, and m = 1, 2,..., N c2 ;

[0030] Collect the maximum amplitude value, peak arrival time, and total energy of the reflected wave of the ground penetrating radar located at the vault of the tunnel section in the second type of sensor, and calculate the average value. The formula is as follows:

[0031]

[0032] where, sd2 max , td2 maxEd1 and Ed2 respectively represent the maximum amplitude value, peak arrival time, and average value of the total energy of the reflected wave of the ground penetrating radar located at the vault of the tunnel section in the second type of sensor, N d2 represents the total amount of the ground penetrating radar located at the vault of the tunnel section in the second type of sensor, sd2 n td2 n and Ed2 n respectively represent the maximum amplitude value, peak arrival time, and total energy of the reflected wave of the nth ground penetrating radar located at the vault of the tunnel section in the second type of sensor. n represents the number of the ground penetrating radars located on both side walls of the tunnel section in the second type of sensor. n is a positive integer, and n = 1, 2,..., N d2 .

[0033] Furthermore, the method for generating the difference degree index based on the offset degree data is as follows:

[0034] Generate a wall error index based on the average values of the maximum amplitude value, peak arrival time, and total energy of both side walls of the tunnel section obtained by the first type of sensor and the second type of sensor. The formula is as follows:

[0035]

[0036] where QM w represents the wall error index.

[0037] Generate a vault error index based on the average values of the maximum amplitude value, peak arrival time, and total energy of the vault of the tunnel section obtained by the first type of sensor and the second type of sensor. The formula is as follows:

[0038]

[0039] where GD w represents the vault error index;

[0040] Generate a difference degree index by comprehensively considering the wall error index and the vault error index. The formula is as follows:

[0041] CYz = ω 1 *GD w + ω 2 *QM w

[0042] where CYz represents the difference degree index, ω 1 and ω 2 respectively represent the vault weight coefficient and the wall weight coefficient. ω 1 > ω 2 > 0, and ω 1 + ω 2 = 1.

[0043] Further, after performing a fast Fourier transform on the reflected wave data collected by the first type of sensor, the reflected wave data is converted into a complex number sequence composed of multiple complex numbers. Each complex number represents a frequency component. For each complex number sequence, a modulus calculation is performed to obtain the amplitude of each frequency component. The frequency that maximizes the amplitude of the frequency component is found and calibrated as the main frequency of the reflected wave data. The two frequency points where the amplitude drops to the maximum amplitude at the main frequency are found, and the frequency bandwidth is defined as the distance between these two frequency points.

[0044] Further, the formula for calculating the average value of the main frequency data and the frequency bandwidth data of the reflected wave data collected by the first type of sensor on both side walls is:

[0045]

[0046] where fc p and Bc p respectively represent the average values of the main frequency data and the frequency bandwidth data of the reflected waves of the ground penetrating radars located on both side walls of the tunnel section in the first type of sensor. N C1 represents the total number of ground penetrating radars located on both side walls of the tunnel section in the first type of sensor. fc pi and Bc pi respectively represent the main frequency and the frequency bandwidth of the reflected waves of the i-th ground penetrating radar located on both side walls of the tunnel section in the first type of sensor. i represents the number of the ground penetrating radars located on both side walls of the tunnel section in the first type of sensor, and i is a positive integer, and i = 1, 2,..., N c1 ;

[0047] The formula for calculating the average value of the main frequency data and the frequency bandwidth data of the reflected wave data collected by the first type of sensor on the vault is:

[0048]

[0049] where fd p and Bd p respectively represent the average values of the main frequency data and the frequency bandwidth data of the reflected waves of the ground penetrating radars located on the vault of the tunnel section in the first type of sensor. N d1 represents the total number of ground penetrating radars located on the vault of the tunnel section in the first type of sensor. fd pj and Bd pj respectively represent the main frequency and the frequency bandwidth of the reflected waves of the j-th ground penetrating radar located on the vault of the tunnel section in the first type of sensor. j represents the number of the ground penetrating radars located on both side walls of the tunnel section in the first type of sensor, and j is a positive integer, and j = 1, 2,..., N d1 ​

[0050] Furthermore, the calculation formula for the stability uniformity index of the tunnel section without completed support is as follows:

[0051]

[0052] Among them, ZJz represents the stability uniformity index, ω 1 and ω 2 respectively represent the vault weight coefficient and the wall weight coefficient, ω 1 > ω 2 > 0, and ω 1 + ω 2 = 1.

[0053] Furthermore, through comprehensive analysis and processing of the difference degree index and the stability uniformity index, a risk analysis model is constructed, and the specific formula for the support risk index of the tunnel section without completed support is as follows:

[0054]

[0055] Among them, ZXz represents the support risk index, ZJz represents the stability uniformity index, CYz represents the difference degree index, ∈ is a constant used to avoid the denominator being zero, and 10 ―9 ≤ ∈ ≤ 10 ―6 ;

[0056] When judging whether to issue a support warning, if ZXz ≥ ZXy, a risk warning for the tunnel section without completed support is issued; otherwise, no warning is issued. ZXy represents the safety threshold..

[0057] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0058] By classifying ground-penetrating radar into two types of sensors and placing them in the supported and unsupported sections respectively, the present invention can simultaneously obtain geological data under two different construction states, thereby establishing a benchmark comparison system. This setting allows for the flexible utilization of information from the supported section to perform more accurate risk prediction for the unsupported section. By extracting various characteristic indexes of the reflected wave, such as the peak arrival time, maximum amplitude value, total energy, and main frequency and frequency bandwidth, the solution realizes multi-parameter comprehensive analysis. This comprehensive data analysis overcomes the deficiency of single data point analysis in traditional methods and provides richer geological information.

[0059] The present invention constructs a difference degree index and a stability uniformity index. These two new indexes provide a more forward-looking perspective for risk analysis. Combining with the risk analysis model, the support risk index can be output, enabling more timely identification of potential problems in the unsupported section and improving the overall construction safety and efficiency. The present invention effectively solves the limitations of traditional methods in risk assessment of unsupported tunnel sections. Description of the Drawings

[0060] Figure 1 This is a schematic diagram of the overall method flow of the present invention. Detailed Description of the Invention

[0061] In order to make the objectives, technical solutions, and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below in conjunction with specific embodiments.

[0062] It should be noted that unless otherwise defined, the technical terms or scientific terms used in the present invention should have the ordinary meanings understood by those with ordinary skills in the field to which the present invention belongs. The "first", "second", and similar terms used in the present invention do not indicate any order, quantity, or importance, but are only used to distinguish different components. The terms such as "including" or "comprising" mean that the elements or objects appearing before this word cover the elements or objects listed after this word and their equivalents, without excluding other elements or objects. The terms such as "connected" or "coupled" are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. The terms such as "upper", "lower", "left", "right", etc. are only used to represent relative positional relationships, and when the absolute position of the object being described changes, the relative positional relationship may also change accordingly.

[0063] Embodiment:

[0064] Please refer to Figure 1 , the present invention provides a technical solution:

[0065] A warning method for the support of surrounding rocks in a mined tunnel, the specific steps include:

[0066] Step 1: Install ground penetrating radars on the two side walls and the vault of the tunnel section, set the ground penetrating radars installed in the tunnel section where the support has not been completed as the first type of sensors, set the ground penetrating radars installed in the tunnel section where the support has been completed as the second type of sensors, and obtain the reflected wave data of all ground penetrating radars.

[0067] In this embodiment, a ground penetrating radar is installed at the center of the vault, and the spacing between all ground penetrating radars at the vault is the same, and the spacing is calibrated as k d , all ground penetrating radars installed on the two side walls of the tunnel section are on the same horizontal plane, and the spacing between all ground penetrating radars on the two side walls is also the same, and the spacing is calibrated as k c , and k c = 1.5 * k d .

[0068] When deploying ground-penetrating radar (GPR), determine the start and end positions of the tunnel sections where GPR needs to be deployed, including sections without completed support and sections with completed support. According to the support status of the tunnel, set the GPR in the tunnel sections without completed support as the first type of sensor, and set the GPR in the tunnel sections with completed support as the second type of sensor. When deploying GPR at the central position of the vault, ensure that it is aligned with the center line of the tunnel.

[0069] When installing GPR on the side walls of the tunnel, it is necessary to ensure that the installation heights are the same. Although the possible structures and environmental conditions of the two side walls may be different, the installation heights and positions of the radar equipment should be the same on both the left and right sides to ensure the symmetry and consistency of detection.

[0070] The tunnel side wall is a vertical plane, while the vault is an arc-shaped or semi-circular structure. The shape of the vault makes it different from the side wall in terms of force-bearing and geological characteristics. The vault of the tunnel usually bears a large load from above, especially the gravity and pressure from the overlying strata. This concentrated force may cause potential problems such as displacement, settlement, and cracks in the vault area. Therefore, the vault requires more intensive monitoring deployment to promptly capture possible structural changes. So, the GPR deployment on the vault is denser, that is, the spacing is smaller.

[0071] Step 2: Based on the reflected wave data obtained from each GPR, respectively obtain the peak arrival time and the maximum amplitude value of each reflected wave. Integrate each reflected wave data to calculate the total energy of each reflected wave. Calculate the average values of the peak arrival time, maximum amplitude value, and total energy of the reflected wave data collected by the first type of sensor and the second type of sensor on the two side walls and the vault.

[0072] In this embodiment, each GPR starts emitting detection waves at the same time point and starts recording data. Mark the moment when the detection waves start to be emitted as the zero moment as a reference point. The frequencies and amplitudes of the detection waves emitted by all GPRs are the same. Scan each reflected wave signal along the time axis to find the maximum value of the signal intensity, and mark this signal intensity as the maximum amplitude value of the reflected wave. Mark the moment value corresponding to the maximum amplitude value as the peak arrival time of the reflected wave. The formula for calculating the total energy of the reflected wave is:

[0073]

[0074] where E represents the total energy of the reflected wave, t max represents the peak arrival time of the reflected wave, s(t) represents the reflected wave data, and t represents the time variable.

[0075] Starting all ground penetrating radars to emit detection waves at the same time point can ensure the synchronization of data. Marking the moment when the detection waves start to be emitted as the zero moment provides a unified time reference point. The timestamps of all data can be calculated based on this reference point, thus simplifying the timing analysis. Ensuring that the frequencies and amplitudes of the detection waves emitted by all ground penetrating radars are the same helps to eliminate the differences between different devices and improve the comparability of data. This makes the reflected wave signals more consistent during analysis, enabling the direct comparison and fusion of data obtained by different radars.

[0076] Scanning each reflected wave signal on the time axis and finding the maximum value of the signal intensity aims to identify the peak of the reflected wave. By obtaining the maximum amplitude value, the intensity and quality of the reflected wave can be determined, thereby judging the characteristics of the detected geological interface or structure. The total energy of the reflected wave can reflect the intensity and clarity of the signal. A larger total energy usually means that the detected reflection characteristics are more significant, which may be related to the physical properties of the geological interface (such as density difference, medium change, etc.).

[0077] The instantaneous power of a continuous-time signal is usually defined as the square of the amplitude of the signal at a certain moment. This is because power is proportional to the square of voltage, and amplitude represents the voltage magnitude, so the square of the amplitude represents the instantaneous power. The total energy of the signal is the integral of the instantaneous power over time, indicating the total amount of energy carried by the signal within a specific time range. The integration process accumulates the energy of the signal from the zero moment to t max to ensure that all signal contributions are included, which is more comprehensive than a single instantaneous measurement.

[0078] The peak arrival time of the reflected wave refers to the time point when the reflected wave returns after being reflected by the geological layer or structure after the radar signal is emitted. The peak arrival time is directly related to the depth of the reflecting surface (such as the geological layer interface, cavity, or groundwater). The longer the time, the deeper the reflecting surface. This is because the propagation speed of radar waves in the ground is fixed. The longer the propagation time, the farther the wave travels in the ground. The peak arrival time can also reflect the propagation characteristics of the medium. The electromagnetic wave propagation speeds of different materials are different. By analyzing the reflected signals at different times, the properties of the geological layer can be inferred.

[0079] The maximum amplitude value of the reflected wave refers to the maximum value of the reflected wave signal intensity. The maximum amplitude value is related to the reflection ability of the reflecting surface. A larger amplitude usually means that there is a large difference in dielectric constant between the reflecting surface and the surrounding medium, or the reflecting surface is relatively smooth and flat. If the signal amplitude is small, it may indicate that the radar wave has encountered significant attenuation during propagation, which may be due to highly absorbent materials underground, scattering effects, or a long signal propagation path.

[0080] The total energy represents the overall strength of the signal, rather than just the peak value at a single moment. This reflects the overall characteristics of the reflecting surface, including the reflection ability, surface area size, and the propagation effect of radar waves in this area. A higher energy value may indicate a very prominent reflecting surface, such as an underground cavity, a strong discontinuous interface, etc.; a lower energy may indicate that the radar waves have undergone multiple scatterings or the reflecting surface is relatively dispersed, resulting in less reflected energy.

[0081] Further, the specific logic for calculating the average values of the peak arrival time, maximum amplitude value, and total energy of the reflected wave data collected by the first - type sensors on both side walls and the vault is as follows:

[0082] Collect the maximum amplitude value, peak arrival time, and total energy of the reflected waves of the ground - penetrating radar on both side walls of the tunnel section in the first - type sensors, and calculate the average value. The formula is as follows:

[0083]

[0084] Among them, sc1 max , tc1 max and Ec1 respectively represent the average values of the maximum amplitude value, peak arrival time, and total energy of the reflected waves of the ground - penetrating radar on both side walls of the tunnel section in the first - type sensors. N C1 represents the total number of the ground - penetrating radars on both side walls of the tunnel section in the first - type sensors. sc1 i , tc1 i and Ec1 i respectively represent the maximum amplitude value, peak arrival time, and total energy of the reflected waves of the i - th ground - penetrating radar on both side walls of the tunnel section in the first - type sensors. i represents the number of the ground - penetrating radars on both side walls of the tunnel section in the first - type sensors. i is a positive integer, and i = 1, 2, …, N C1 .

[0085] Collect the maximum amplitude value, peak arrival time, and total energy of the reflected waves of the ground - penetrating radar on the vault of the tunnel section in the first - type sensors, and calculate the average value. The formula is as follows:

[0086]

[0087] Among them, sd1 max , td1 max and Ed1 respectively represent the average values of the maximum amplitude value, peak arrival time, and total energy of the reflected waves of the ground - penetrating radar on the vault of the tunnel section in the first - type sensors. N d1 represents the total number of the ground - penetrating radars on the vault of the tunnel section in the first - type sensors. sd1 j , td1 j and Ed1j respectively represent the maximum amplitude value, peak arrival time, and total energy of the reflected wave of the j-th ground penetrating radar located at the vault of the tunnel section in the first type of sensors. j represents the number of the ground penetrating radars located on both side walls of the tunnel section in the first type of sensors. j is a positive integer, and j = 1, 2, …, N d1 .

[0088] Furthermore, the specific logic for calculating the average values of the peak arrival time, maximum amplitude value, and total energy of the reflected wave data collected by the second type of sensors on both side walls and the vault is as follows:

[0089] Collect the maximum amplitude value, peak arrival time, and total energy of the reflected wave of the ground penetrating radars located on both side walls of the tunnel section in the second type of sensors, and calculate the average value. The formula used is:

[0090]

[0091] where sc2 max , tc2 max and Ec2 respectively represent the average values of the maximum amplitude value, peak arrival time, and total energy of the reflected wave of the ground penetrating radars located on both side walls of the tunnel section in the second type of sensors. N C2 represents the total number of the ground penetrating radars located on both side walls of the tunnel section in the second type of sensors. sc2 m , tc2 m and Ec2 m respectively represent the maximum amplitude value, peak arrival time, and total energy of the reflected wave of the m-th ground penetrating radar located on both side walls of the tunnel section in the second type of sensors. m represents the number of the ground penetrating radars located on both side walls of the tunnel section in the second type of sensors. m is a positive integer, and m = 1, 2, …, N c2 .

[0092] Collect the maximum amplitude value, peak arrival time, and total energy of the reflected wave of the ground penetrating radars located at the vault of the tunnel section in the second type of sensors, and calculate the average value. The formula used is:

[0093]

[0094] where sd2 max , td2 max and Ed2 respectively represent the average values of the maximum amplitude value, peak arrival time, and total energy of the reflected wave of the ground penetrating radars located at the vault of the tunnel section in the second type of sensors. N d2 represents the total number of the ground penetrating radars located at the vault of the tunnel section in the second type of sensors. sd2 n , td2 n and Ed2 nrespectively represent the maximum amplitude value, peak arrival time, and total energy of the reflected wave of the nth ground penetrating radar located at the vault of the tunnel section in the second type of sensor. n represents the number of the ground penetrating radar located on the two side walls of the tunnel section in the second type of sensor. n is a positive integer, and n = 1, 2, …, N d2 。

[0095] By averaging multiple sets of reflected wave data at the same type of location and under the same conditions, a more representative result can be obtained. It is very important to comprehensively understand the geological characteristics of the tunnel walls and vault because individual measurement values may not fully reflect the actual situation. The process of calculating the average value is to improve the reliability, representativeness, and stability of the data, so that clearer and more accurate results can be obtained during analysis and comparison, facilitating the understanding and evaluation of the geological characteristics of the tunnel. The average values of the reflected waves from the vault and the walls need to be calculated separately because there are significant differences in their structural forms, stress distributions, and geological environments, resulting in different reflected wave characteristics. Separately calculating can more accurately capture these differences and avoid introducing biases by mixing data from different structural parts, thus providing more accurate analysis results.

[0096] Step 3: Analyze the average values of the peak arrival time, maximum amplitude value, and total energy of the first type of sensor and the second type of sensor on the two side walls and the vault, generate the offset degree data of the reflected waves collected by the second type of sensor relative to the reflected waves collected by the first type of sensor, and generate a difference degree index based on the offset degree data.

[0097] In an unsupported tunnel environment, the geological materials around the tunnel are still in a natural state. Due to the ineffective management and control of the formation stress, phenomena such as loosening, displacement, and crack development may occur in the materials around the tunnel, and there may even be groundwater seepage. By applying a support structure (such as steel frames, shotcrete, etc.) to a supported tunnel, the geological environment around the tunnel is improved, the formation is stabilized, and the ground stress is effectively managed. The role of the support system is to keep the formation integral, reduce displacement and loosening, and increase the rigidity of the formation and the ability to reflect radar waves.

[0098] In an unsupported environment, materials such as rock and soil layers around the tunnel will become loose and uneven due to stress release and displacement. Since the density and rigidity of the materials are relatively low, the energy of the reflected wave will rapidly attenuate during propagation, resulting in a low signal amplitude received by the sensor. The presence of looseness or fractures makes the wave propagation path more complex, with more diffraction and scattering, causing the arrival time of the wave peak to be later than that of a supported tunnel. Due to multiple reflections and scattering, the total energy of the reflected wave is significantly reduced. When a support structure is installed in the tunnel, the support material itself has high rigidity and density. Support materials (such as steel, concrete, etc.) have a large density and a complete structure, reducing the attenuation of the reflected wave and increasing the maximum amplitude value received by the sensor. The uniformity and high rigidity of the support material make the wave propagation more direct and the path simpler, with the wave peak arriving earlier. Since the support material can effectively reflect radar waves, reducing energy dissipation, the total energy of the reflected wave increases.

[0099] When the differences in the characteristics of the reflected waves between the supported tunnel and the unsupported tunnel are significant, it indicates that the support material has a strong reinforcement effect on the surrounding strata of the tunnel, changing the geological environment and the wave propagation path. Conversely, if the differences are small, it may indicate the difference in the effects between supported and unsupported conditions, and the geological environment around the tunnel changes little compared to the unsupported state. A larger difference means that the support structure has a more significant effect on the tunnel, reflecting that the tunnel support is more effective in constraining the strata, redistributing stress, and densifying the materials. These changes help improve the stability of the tunnel, reduce the risk of collapse or deformation, indicating a better effect of the tunnel support system.

[0100] In this embodiment, the method for generating the difference degree index based on the offset degree data is as follows:

[0101] Generate a wall error index based on the average values of the maximum amplitude, peak arrival time, and total energy of the two side walls of the tunnel section obtained by the first type of sensor and the second type of sensor. The formula is as follows:

[0102]

[0103] where QM w represents the wall error index.

[0104] Generate a vault error index based on the average values of the maximum amplitude, peak arrival time, and total energy of the vault of the tunnel section obtained by the first type of sensor and the second type of sensor. The formula is as follows:

[0105]

[0106] where GD w represents the vault error index.

[0107] Each ratio represents the relative deviation degree of a characteristic parameter, and the sum of the three provides a comprehensive deviation measure. This summation form can effectively integrate the deviations of each characteristic parameter and provide an overall difference measure. The wall error index quantifies the difference in the presence or absence of support reflected waves in the measurement of wall reflected waves through the relative deviation degree. In this way, a comprehensive and standardized difference index between supported and unsupported walls can be obtained. The vault error index quantifies the difference in the presence or absence of support reflected waves in the measurement of wall reflected waves and obtains the differences between vault characteristics.

[0108] The wall error index can quantify the difference in the characteristics of wall reflected waves under supported and unsupported conditions. By comparing the reflected wave characteristics of the walls on both sides of the unsupported and supported tunnel sections, the influence of the support on the wall stability can be identified. If the wall error index is large, it indicates that the maximum amplitude value, peak arrival time, and total energy of the wall reflected waves in the supported tunnel section are significantly improved compared to the unsupported tunnel section, indicating that the support structure is effective and can better reflect radar waves, indicating that the wall maintains better stability and integrity, reducing looseness and displacement. If it is small, it indicates that the difference in the reflected wave characteristics of the wall under unsupported and supported conditions is not obvious, and even in some cases, the intensity of the reflected wave weakens, indicating that the support effect is poor, there are potential structural problems with the wall, or the geological conditions have not been significantly improved.

[0109] The vault error index can quantify the difference in the reflected wave characteristics of the tunnel vault under supported and unsupported conditions. By comparing the maximum amplitude value, peak arrival time, and total energy of the vault, the influence of the support structure in the vault area can be evaluated. If the vault error index is large, it indicates that the reflected wave characteristics of the vault in the supported tunnel section are significantly improved compared to the vault in the unsupported tunnel section, indicating that the support structure at the vault is effective, enhancing the intensity of the reflected wave, and the stability of the vault is significantly improved. The support structure can effectively manage the stress distribution of the vault. If it is small, it indicates that the difference in the reflected wave characteristics of the vault under unsupported and supported conditions is not obvious, and even in some cases, the amplitude of the reflected wave weakens, which may indicate that the support effect is not obvious, there are potential safety hazards in the vault, or the support structure fails to effectively improve the stability of the vault.

[0110] The difference degree index is comprehensively generated based on the wall error index and the vault error index, and the formula is as follows:

[0111] CYz = ω 1 *GD w + ω 2 *QM w

[0112] Among them, CYz represents the difference degree index, ω 1 and ω 2respectively represent the vault weight coefficient and the wall weight coefficient, ω 1 > ω 2 > 0, and ω 1 + ω 2 = 1.

[0113] The construction logic of the difference degree index lies in comprehensively evaluating the reflection characteristics of the wall and vault of the tunnel structure to reflect the safety and stability of the overall structure under the support conditions. Specifically, the construction logic of the formula, the weight setting, and the numerical meaning of this index will be described in detail below.

[0114] When the vault error index and the wall error index are small, the difference degree index is small, and the difference between without support and with support is not significant, indicating that the self-supporting effect of the tunnel is better, indicating that the self-supporting structure of the unsupported tunnel is more stable. By combining the reflection characteristics of the vault and the wall, the overall safety of the tunnel structure can be comprehensively reflected. This comprehensive index can provide a more comprehensive evaluation result. The purpose of setting the weight coefficient is to affect the calculation of the difference degree index according to the actual importance of the structure. The vault plays a more crucial role in the overall stability of the tunnel because the load and pressure borne by the vault directly affect the structural stability of the entire tunnel. A larger weight is set for the vault, and the normalization of the weight coefficient is ensured, so that the weights maintain a relatively reasonable proportional relationship in the calculation, ensuring the effectiveness of the comprehensive index.

[0115] The smaller the difference degree index, the relatively smaller the vault error index and the wall error index, indicating that the self-supporting effect of the tunnel is good. Even without support, the side structure is stable and can effectively reflect better reflected wave characteristics. The larger the difference degree index, the relatively larger the vault error index and the wall error index, indicating that there may be poor self-supporting effect or structural problems. By constructing the difference degree index, the reflected wave characteristics of the vault and the wall can be effectively integrated, and the overall stability of the tunnel structure under the support conditions can be quantified. The setting of the weight coefficient takes into account the relative importance of different parts in structural safety, and the value of the index reflects the quality of the support effect.

[0116] Step 4: Perform a fast Fourier transform on the reflected wave data collected by the first type of sensor, convert the reflected wave data from the time domain to the frequency domain, obtain the main frequency data and frequency bandwidth data of the reflected wave data, and calculate the average values of the main frequency data and frequency bandwidth data of the reflected wave data collected by the first type of sensor on both side walls and the vault respectively.

[0117] In this embodiment, after performing a fast Fourier transform on the reflected wave data collected by the first type of sensor, the reflected wave data is converted into a complex sequence composed of multiple complex numbers. Each complex number represents a frequency component. For each complex sequence, a modulus calculation is performed to obtain the amplitude of each frequency component. The frequency that makes the amplitude of the frequency component the largest is found and calibrated as the main frequency of the reflected wave data. The two frequency points that make the amplitude drop to the maximum amplitude at the main frequency are found, and the frequency bandwidth is defined as the distance between these two frequency points. After performing the fast Fourier transform, the reflected wave data is transformed from the time domain to the frequency domain, and the main frequency and frequency bandwidth data of the reflected wave can be extracted. What is obtained after the fast Fourier transform is a complex sequence, which represents the amplitude and phase of the signal at each frequency. The main frequency is the frequency with the maximum value in the amplitude spectrum, that is, the frequency where the energy in the signal is most concentrated. The frequency corresponding to the maximum amplitude value in the reflected wave data is the main frequency of the signal.

[0118] The main frequency is the frequency component with the most concentrated energy in the reflected wave signal. For an unsupported tunnel, the main frequency can reflect the stiffness and density of the material of the tunnel sidewall itself. When the material of the tunnel sidewall is relatively uniform, the main frequency is usually relatively stable. If the main frequencies at different positions vary greatly, it may mean that there are significant differences in the materials of the sidewalls of the unsupported tunnel. The frequency bandwidth refers to the frequency range that contains the main energy components in the spectrum. A narrower bandwidth usually indicates that the reflected wave has passed through a uniform and continuous material, the waveform is relatively simple, and the energy is concentrated near the main frequency. A wider bandwidth means that there are discontinuities, heterogeneity, or multi-layer structures in the material, resulting in a complex waveform and the energy being distributed over a wider frequency range.

[0119] If the material distribution of the tunnel sidewall is uniform, the main frequency should generally be close to the same at different positions, and at the same time, the bandwidth is relatively narrow, indicating that the material properties are relatively consistent and the fluctuations are small. If the main frequencies are significantly different at different measurement points, or the frequency bandwidth changes significantly, this may indicate the non-uniformity of the support structure. For an unsupported tunnel, uniform material means that when there is no support, the self-supporting force is relatively uniform and there will be no local stress conditions, and it is not easy to have risks such as spalling and local collapse due to uneven bearing force.

[0120] Furthermore, the formula for calculating the average value of the main frequency data and frequency bandwidth data of the reflected wave data collected by the first type of sensor on both side walls is:

[0121] Among them, fc

[0122]

[0123] and Bc p and prespectively represent the average values of the main frequency data and the frequency bandwidth data of the reflected waves of the ground penetrating radars located on the two side walls of the tunnel section in a type of sensor, N C1 represents the total number of the ground penetrating radars located on the two side walls of the tunnel section in the first type of sensor, fc pi and Bc pi respectively represent the main frequency and the frequency bandwidth of the reflected wave of the i-th ground penetrating radar located on the two side walls of the tunnel section in the first type of sensor. i represents the number of the ground penetrating radars located on the two side walls of the tunnel section in the first type of sensor, i is a positive integer, and i = 1, 2,..., N c1 ;

[0124] The formula for calculating the average values of the main frequency data and the frequency bandwidth data of the reflected wave data collected by the first type of sensor at the vault is:

[0125]

[0126] where, fd p and Bd p respectively represent the average values of the main frequency data and the frequency bandwidth data of the reflected waves of the ground penetrating radars located at the vault of the tunnel section in the first type of sensor, N d1 represents the total number of the ground penetrating radars located at the vault of the tunnel section in the first type of sensor, fd pj and Bd pj respectively represent the main frequency and the frequency bandwidth of the reflected wave of the j-th ground penetrating radar located at the vault of the tunnel section in the first type of sensor. j represents the number of the ground penetrating radars located on the two side walls of the tunnel section in the first type of sensor, j is a positive integer, and j = 1, 2,..., N d1 ..

[0127] Step 5: Generate the stability uniformity index of the tunnel section without completed support based on the average values of the main frequency data and the frequency bandwidth data collected by the first type of sensor on the two side walls and the vault, and in combination with the main frequency data and the frequency bandwidth data obtained by the first type of sensor.

[0128] In this embodiment, the formula for calculating the stability uniformity index of the tunnel section without completed support is:

[0129]

[0130] where, ZJz represents the stability uniformity index, ω 1 and ω 2 respectively represent the vault weight coefficient and the wall weight coefficient, ω 1 > ω 2 > 0, and ω 1 + ω 2 = 1.

[0131] The stability uniformity index is a parameter that measures the structural uniformity of a tunnel when no support is provided. It reflects the consistency of the unsupported tunnel section in terms of its own structure. The calculation of the index comprehensively considers the differences in ground penetrating radar data between the crown and the sidewalls, and measures the degree of data dispersion in the form of variance. If the deviation of the main frequency and frequency bandwidth of the crown and sidewalls from their average values is small, the stability uniformity index will be small, indicating better uniformity of the tunnel's own side structure. Conversely, if the deviation is large, the stability uniformity index will be large, indicating poor uniformity.

[0132] When the stability uniformity index is large, it indicates that there are significant differences in the main frequency and frequency bandwidth at different positions of the tunnel's own side structure, reflecting the non-uniformity of the side structure. This may be due to factors such as the tunnel being located in an area with non-uniform geological materials. A large value may indicate potential safety hazards in the self-support when no support is provided, and there may be risks of local collapse or falling.

[0133] When the stability uniformity index is small, it indicates that the main frequency and frequency bandwidth data of the tunnel's own sidewall structure at different positions are relatively consistent, reflecting better uniformity of the overall structure. This means that the overall performance of the tunnel's own sidewall structure is relatively stable, without obvious weaknesses or discontinuities. A smaller support uniformity index value indicates that the support structure of the tunnel section is relatively healthy, and the overall structural performance is relatively reliable. The support structure at the crown is more critical, so the weight of the crown is larger, and the weight of the sidewall is smaller.

[0134] Step 6: Conduct a comprehensive analysis and processing of the difference degree index and the stability uniformity index, construct a risk analysis model, obtain the support risk index of the tunnel section without completed support, and compare the support risk index with the safety threshold to determine whether to issue a risk warning.

[0135] In this embodiment, the specific formula for conducting a comprehensive analysis and processing of the difference degree index and the stability uniformity index, constructing a risk analysis model, and obtaining the support risk index of the tunnel section without completed support is as follows:

[0136]

[0137] Where, ZXz represents the support risk index, ZJz represents the stability uniformity index, CYz represents the difference degree index, ∈ is a constant used to avoid the denominator being zero, and 10 ―9 ≤∈≤10 ―6 。

[0138] The overall value of the stability uniformity index and the difference degree index is comprehensively evaluated by taking the average of the sum of squares. The logarithmic operation compresses the growth rate of the result. Especially when the stability uniformity index and the difference degree index increase, this part of the result will no longer grow linearly. If both the stability uniformity index and the difference degree index are large, it means that the self-supporting effect of the unsupported tunnel is poor and there are large structural fluctuations. Therefore, the support risk index will increase. When the stability uniformity index and the difference degree index are small, the support risk index will become small, indicating that the support structure is relatively stable.

[0139] The product of the stability uniformity index and the difference degree index is processed, and its non-linear influence is enhanced through exponential operation. The denominator CYz + ZJz + ∈ is used for normalization, so that when the two indices are close, the change in the exponential part is relatively smooth. The exponential operation amplifies the interaction effect of the support uniformity index and the difference degree index. When both of these indices are high, this part of the result will increase significantly, meaning that the stability of the self-supporting effect is poor and there may be risks of non-uniformity and instability in the structure. On the contrary, if both indices are small, the exponential part will tend to 1 and the amplification effect on the result is not obvious.

[0140] Introducing a small ∈ can effectively prevent the denominator from being zero, thus ensuring the stability and effectiveness of the formula. The value of ∈ should be small enough to ensure that its influence on the result is very small in actual calculations. The selection range of 10 ―9 to 10 ―6 can ensure that the value of ∈ will not significantly affect the calculation of the support uniformity index and the difference degree index, especially when these values are also small.

[0141] The support risk index is a quantitative index reflecting the stability of the self-sidewall support system of the unsupported tunnel. It constructs a formula containing a non-linear amplification effect based on the interaction effect of the difference degree index and the stability uniformity index. A larger support risk index means that there may be instability or structural weak points in the tunnel's self-supporting structure, and the self-supporting effect is poor; while a smaller support risk index indicates that the self-supporting structure is relatively uniform and stable, and the support effect is good. The support effect index can accurately reflect the tunnel's self-supporting effect and provide a basis for safety assessment and support warning.

[0142] When determining whether to issue a support warning, if ZXz ≥ ZXy, a risk warning for the unfinished support tunnel section is issued; otherwise, no warning is issued. ZXy represents the safety threshold. ZXz is an indicator that combines the difference degree index and the stability uniformity index and is used to evaluate the stability of the tunnel's own support. It reflects the uniformity and difference of the support structure. The larger the value, the more problems exist in the self-support structure and the worse the support effect. ZXy is a preset threshold that represents the maximum instability or risk level that the support structure can accept and is determined based on engineering experience, design specifications, or safety standards. It reflects the maximum degree of support problems allowed in tunnel engineering.

[0143] When ZXz ≥ ZXy, it indicates that the support risk index has exceeded the set safety threshold, which means that the stability of the tunnel's own support structure may have reached an unacceptable level. Therefore, a support deficiency warning needs to be issued to remind relevant engineering personnel of the risk of local collapse or falling of the tunnel.

[0144] When ZXz < ZXy, it indicates that the support risk index is within the acceptable range, and the self-support structure is still within the control of the safety standard, with a relatively small risk of local collapse or falling. Therefore, no support deficiency warning is issued, and the effect of the tunnel's own support is considered safe.

[0145] The above formulas are all dimensionless and take their numerical values for calculation. The formula is obtained by collecting a large amount of data for software simulation to get a formula closest to the actual situation. The preset parameters in the formula are set by those skilled in the art according to the actual situation.

[0146] The above embodiments can be implemented in whole or in part by software, hardware, firmware, or any other combination. When implemented using software, the above embodiments can be implemented in whole or in part in the form of a computer program product. Those skilled in the art can realize that the units and algorithm steps of each example described in combination with the embodiments disclosed herein can be implemented by electronic hardware or a combination of computer software and electronic hardware. Whether these functions are executed by hardware or software methods depends on the specific application and design constraints of the technical solution.

[0147] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units. They can be located in one place or distributed to multiple network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0148] The above are only specific embodiments of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present application can easily think of changes or substitutions, which should all be covered within the protection scope of the present application.

Claims

1. A method for early warning of surrounding rock support of a dark tunnel, characterized in that: The specific steps include: Step 1: Deploy geological radars on the walls and vaults on both sides of the tunnel section, and set the geological radars deployed in the tunnel section without support as the first type of sensor, and set the geological radars deployed in the tunnel section with support as the second type of sensor, and obtain the reflected wave data of all geological radars; Step 2: According to the reflected wave data of each geological radar, obtain the peak arrival time and the maximum amplitude value of each reflected wave respectively, integrate each reflected wave data, calculate the total energy of each reflected wave, and calculate the average value of the peak arrival time, maximum amplitude value and total energy of the reflected wave data collected by the first type of sensor and the second type of sensor on the walls and the vault on both sides respectively; Step 3: Analyze the average values ​​of the peak arrival time, maximum amplitude value and total energy of the first type of sensors and the second type of sensors on the walls and the vault on both sides, generate the offset degree data of the reflected wave collected by the second type of sensors relative to the reflected wave collected by the first type of sensors, and generate the difference degree index based on the offset degree data; Step 4: Perform fast Fourier transform on the reflected wave data collected by the first type of sensor, convert the reflected wave data from the time domain to the frequency domain, obtain the main frequency data and frequency bandwidth data of the reflected wave data, and calculate the average values ​​of the main frequency data and frequency bandwidth data of the reflected wave data collected by the first type of sensor on the walls and the vault on both sides; Step 5: Based on the average of the main frequency data and the frequency bandwidth data collected by the first type of sensors on the walls and the vault on both sides, and combined with the main frequency data and the frequency bandwidth data obtained by the first type of sensors, a stability uniformity index of the tunnel section without support is generated; Step 6: Comprehensively analyze and process the difference degree index and the stability uniformity index, build a risk analysis model, obtain the support risk index of the unsupported tunnel section, compare the support risk index with the safety threshold, and determine whether to issue a risk warning.

2. The method for early warning of surrounding rock support of a dark tunnel according to claim 1, characterized in that: The geological radar is arranged in the center of the vault, and the spacing between the geological radars at all vaults is the same, and the spacing is calibrated as k. d All the geological radars arranged on the walls and vaults of the tunnel section are on the same horizontal plane, and the spacing between the geological radars on the walls is the same, and the spacing is calibrated as k c , and k c =1.5*k d .

3. The method for early warning of surrounding rock support of a dark tunnel according to claim 1, characterized in that: Each geological radar starts to emit detection waves and start recording data at the same time. The time when the detection wave starts to be emitted is calibrated as time zero as the reference point. The frequency and amplitude of the detection waves emitted by all geological radars are the same. Each reflected wave signal is scanned along the time axis to find the maximum signal strength. The signal strength is calibrated as the maximum amplitude value of the reflected wave, and the time value corresponding to the maximum amplitude value is calibrated as the peak arrival time of the reflected wave. The formula for calculating the total energy of the reflected wave is: Where E represents the total energy of the reflected wave, t max represents the peak arrival time of the reflected wave, s(t) represents the reflected wave data, and t represents the time variable.

4. The method for early warning of surrounding rock support of a dark tunnel according to claim 1, characterized in that: The specific logic for calculating the average value of the peak arrival time, maximum amplitude value and total energy of the reflected wave data collected by the first type of sensors on the walls and the vault on both sides is: The maximum amplitude, peak arrival time and total energy of the reflected waves of the geological radar located on the walls of both sides of the tunnel section in the first type of sensor are collected, and the average value is calculated based on the formula: Among them, sc1 max 、tc1 max and Ec1 represent the maximum amplitude, peak arrival time and average total energy of the reflected waves of the geological radar located on the walls on both sides of the tunnel section in the first type of sensor, respectively. C1 Indicates the total amount of geological radars located on both sides of the tunnel wall in the first category of sensors, sc1 i 、tc1 i and Ec1 i They respectively represent the maximum amplitude value, peak arrival time and total energy of the reflected wave of the i-th geological radar located on the walls of both sides of the tunnel section in the first type of sensor, i represents the number of the geological radar located on the walls of both sides of the tunnel section in the first type of sensor, i is a positive integer, and i=1, 2, …, N C1 ; The maximum amplitude, peak arrival time and total energy of the reflected wave of the geological radar located at the vault of the tunnel section in the first type of sensor are collected, and the average value is calculated based on the formula: Among them, sd1 max 、td1 max and Ed1 represent the maximum amplitude, peak arrival time and average total energy of the reflected wave of the geological radar located at the top of the tunnel section in the first type of sensor, respectively. d1 Indicates the total amount of ground-penetrating radar located at the top of the tunnel section in the first category of sensors, sd1 j 、td1 j and Ed1 j They respectively represent the maximum amplitude value, peak arrival time and total energy of the reflected wave of the jth geological radar located on the vault of the tunnel section in the first type of sensor, j represents the number of the geological radar located on the walls on both sides of the tunnel section in the first type of sensor, j is a positive integer, and j=1, 2, ..., N d1 .

5. The method for early warning of surrounding rock support of a dark tunnel according to claim 4, characterized in that: The specific logic for calculating the average value of the peak arrival time, maximum amplitude value and total energy of the reflected wave data collected by the second type of sensors on the walls on both sides and the vault is: The maximum amplitude, peak arrival time and total energy of the reflected waves of the geological radar located on the walls of both sides of the tunnel section in the second type of sensor are collected, and the average value is calculated based on the formula: Among them, sc2 max 、tc2 max and Ec2 represent the maximum amplitude, peak arrival time and average total energy of the reflected waves of the geological radar located on the walls on both sides of the tunnel section in the second type of sensor, respectively. C2 Indicates the total amount of geological radars located on both sides of the tunnel wall in the second type of sensors, sc2 m 、tc2 m and Ec2 m They respectively represent the maximum amplitude value, peak arrival time and total energy of the reflected wave of the mth geological radar located on the walls of both sides of the tunnel section in the second type of sensor, m represents the number of the geological radar located on the walls of both sides of the tunnel section in the second type of sensor, m is a positive integer, and m=1, 2, …, N c2 ; The maximum amplitude, peak arrival time and total energy of the reflected wave of the geological radar located at the vault of the tunnel section in the second type of sensor are collected, and the average value is calculated based on the formula: Among them, sd2 max 、td2 max and Ed2 represent the maximum amplitude, peak arrival time and average total energy of the reflected wave of the geological radar located at the vault of the tunnel section in the second type of sensor, respectively. d2 Indicates the total amount of geological radar located in the vault of the tunnel section in the second type of sensor, sd2 n 、td2 n and Ed2 n They respectively represent the maximum amplitude value, peak arrival time and total energy of the reflected wave of the nth geological radar located on the vault of the tunnel section in the second type of sensor, n represents the number of the geological radar located on the walls on both sides of the tunnel section in the second type of sensor, n is a positive integer, and n=1, 2, …, N d2 .

6. The method for early warning of surrounding rock support of a dark tunnel according to claim 5, characterized in that: The method for generating the difference index based on the deviation degree data is: The wall error index is generated based on the average value of the maximum amplitude, peak arrival time and total energy of the walls on both sides of the tunnel section obtained by the first type of sensor and the second type of sensor, and the formula is as follows: Among them, QM w represents the wall error index; The vault error index is generated based on the average value of the maximum amplitude value, peak arrival time and total energy of the vault of the tunnel section obtained by the first type of sensor and the second type of sensor, and the formula is as follows: Among them, GD w represents the vault error index; The difference degree index is generated based on the wall error index and the vault error index, and the formula is as follows: CYz=ω1*GD w +ω2*QM w Among them, CYz represents the difference degree index, ω1 and ω2 represent the vault weight coefficient and the wall weight coefficient respectively, ω1>ω2>0, and ω1+ω2=1.

7. The method for early warning of surrounding rock support of a dark tunnel according to claim 1, characterized in that: After fast Fourier transform of the reflected wave data collected by the first type of sensor, the reflected wave data is converted into a complex sequence composed of multiple complex numbers, each complex number represents a frequency component, and modulus calculation is performed on each complex sequence to obtain the amplitude of each frequency component. The frequency that makes the amplitude of the frequency component maximum is found and calibrated as the main frequency of the reflected wave data, and the amplitude that makes the amplitude drop to the maximum amplitude at the main frequency is found. The frequency bandwidth is defined as the distance between the two frequency points.

8. The method for early warning of surrounding rock support of a dark tunnel according to claim 7, characterized in that: The formula for calculating the average value of the main frequency data and the frequency bandwidth data of the reflected wave data collected by the first type of sensor on the walls on both sides is: Among them, fc p and Bc p They represent the average values ​​of the main frequency data and frequency bandwidth data of the reflected waves of the geological radar located on the walls on both sides of the tunnel section in one type of sensor, N C1 represents the total amount of ground-penetrating radars located on both sides of the tunnel wall in the first category of sensors, fc pi and Bc pi They respectively represent the main frequency and frequency bandwidth of the reflected wave of the i-th geological radar located on the walls of both sides of the tunnel section in the first type of sensor, i represents the number of the geological radar located on the walls of both sides of the tunnel section in the first type of sensor, i is a positive integer, and i=1, 2, …, N c1 ; The formula for calculating the average value of the main frequency data and the frequency bandwidth data of the reflected wave data collected by the first type of sensor on the arch is: Among them, fd p and Bd p They represent the average values ​​of the main frequency data and frequency bandwidth data of the reflected wave of the geological radar located at the top of the tunnel section in the first type of sensor, N d1 represents the total amount of ground-penetrating radar located at the top of the tunnel section in the first category of sensors, fd pj and Bd pj They represent the main frequency and frequency bandwidth of the reflected wave of the jth geological radar located on the top of the tunnel section in the first type of sensor, respectively; j represents the number of the geological radar located on the walls on both sides of the tunnel section in the first type of sensor, j is a positive integer, and j=1, 2, ..., N d1 .

9. The method for early warning of surrounding rock support of a dark tunnel according to claim 8, characterized in that: The formula for calculating the stability uniformity index of the unsupported tunnel section is: Wherein, ZJz represents the stability uniformity index, ω1 and ω2 represent the vault weight coefficient and the wall weight coefficient respectively, ω1>ω2>0, and ω1+ω2=1.

10. The method for early warning of surrounding rock support of a dark tunnel according to claim 1, characterized in that: The difference degree index and the stability uniformity index are comprehensively analyzed and processed, and a risk analysis model is constructed to obtain the specific formula of the support risk index of the unfinished support tunnel section: Among them, ZXz represents the support risk index, ZJz represents the stability uniformity index, CYz represents the degree of difference index, ∈ is a constant to avoid the denominator being 0, and 10 -9 ≤∈≤10 -6 ; When judging whether to issue a support warning, if ZXz ≥ ZXy, a risk warning is issued for the tunnel section that has not completed support, otherwise no warning is issued, and ZXy represents the safety threshold.

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