Early warning method for surrounding rock support of subsurface tunnel

Abstract

The invention provides an underground excavation tunnel surrounding rock support early warning method, and relates to the technical field of tunnel support detection, geological radars are divided into two types of sensors which are respectively placed on a supported section and an unsupported section, and geological data in two different construction states can be acquired at the same time, so that a reference comparison system is established; according to the scheme, multiple characteristic indexes such as peak arrival time, maximum amplitude, total energy, main frequency and frequency bandwidth of reflected waves are extracted, multi-parameter comprehensive analysis is achieved, a difference degree index and a stability uniformity index are constructed, the two new indexes provide a more prospective view angle for risk analysis, and the risk analysis accuracy is improved. And in combination with the risk analysis model, the support risk index can be output, so that the identification of the potential problem of the unsupported section is more timely.

Description

Technical Field

[0001] The invention relates to the technical field of tunnel support detection, and in particular to an early warning method for surrounding rock support of a dark-cut tunnel. Background Art

[0002] Tunnel surrounding rock refers to the rock or soil surrounding 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 unsupported tunnel side walls, i.e. the surrounding rock, has always been a core issue of great concern. The risks of unsupported tunnel sections are mainly local collapse and falling of the surrounding rock. With the large-scale advancement of infrastructure projects, how to improve the safety and efficiency of tunnel construction has become a key direction for the development of the industry. At present, 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 upgrading of industry technology and laid the foundation for the realization of intelligent and precise construction.

[0003] In existing technologies, geological radar plays an important role as a key detection tool. Geological 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 tunnel structures. However, current applications are mostly focused on monitoring supported sections, lacking risk prediction for unsupported sections.

[0004] The shortcomings of existing technologies are mainly reflected in the limitations of data analysis and application. Although geological radar can provide rich data, its use in risk assessment of unsupported tunnel sections is limited. Traditional methods often focus on the analysis of a single data point, lack multi-parameter comprehensive analysis methods, and cannot flexibly use the information of supported sections for risk prediction. This leads to the identification of potential problems in unsupported sections not being timely enough, affecting the overall safety and efficiency of construction.

[0005] The above information disclosed in this Background section is only for enhancement of understanding of the background of the present disclosure and therefore it may contain information that does not constitute the prior art that is already known to one of ordinary skill in the art. Summary of the invention

[0006] The object of the present invention is to provide a surrounding rock support early warning method for a dark-excavated tunnel to solve the problems raised in the above-mentioned background technology.

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

[0008] A method for early warning of surrounding rock support of a dark tunnel, comprising the following specific steps:

[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] Furthermore, each geological radar starts to emit detection waves at the same time point and starts to record data. 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:

[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] 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 first type of sensors on the walls on both sides and the vault is:

[0020] 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:

[0021]

[0022] 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 ;

[0023] 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:

[0024]

[0025] 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 .

[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 sensors on the walls on both sides and the vault is as follows:

[0027] 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:

[0028]

[0029] 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 ;

[0030] 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:

[0031]

[0032] Among them, sd2 max 、td2 maxand 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 .

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

[0034] 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:

[0035]

[0036] Among them, QM w Represents the wall error index.

[0037] 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:

[0038]

[0039] Among them, GD w represents the vault error index;

[0040] The difference degree index is generated based on the wall error index and the vault error index, and the formula is as follows:

[0041] CYz=ω1*GD w +ω2*QM w

[0042] 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.

[0043] Furthermore, 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, and a modulus calculation is performed on each complex sequence to obtain the amplitude of each frequency component, and 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.

[0044] Furthermore, 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:

[0045]

[0046] 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 ;

[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 arch is:

[0048]

[0049] 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 .

[0050] Furthermore, the calculation formula for the stability uniformity index of the unsupported tunnel section is:

[0051]

[0052] 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.

[0053] Furthermore, 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:

[0054]

[0055] 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 ;

[0056] When judging whether to issue a support warning, if ZXz ≥ ZXy, a risk warning for the tunnel section that has not completed support is issued, otherwise no warning is issued, and ZXy represents the safety threshold.

[0057] Compared with the prior art, the present invention has the following beneficial effects:

[0058] The present invention divides the geological radar into two types of sensors, which are placed in supported and unsupported sections respectively, so that geological data under two different construction conditions can be obtained simultaneously, thereby establishing a benchmark comparison system. This setting allows flexible use of the information of the supported section to make more accurate risk predictions for the unsupported section. By extracting multiple characteristic indicators of the reflected wave, such as peak arrival time, maximum amplitude value, total energy, main frequency and frequency bandwidth, the scheme realizes multi-parameter comprehensive analysis. This comprehensive data analysis overcomes the shortcomings 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 indicators provide a more forward-looking perspective for risk analysis. Combined with the risk analysis model, the support risk index can be output, making the identification of potential problems in unsupported sections more timely, thereby improving the safety and efficiency of the overall construction. The present invention effectively solves the limitations of traditional methods in risk assessment of unsupported tunnel sections. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] Figure 1 It is a schematic diagram of the overall method flow of the present invention. DETAILED DESCRIPTION

[0061] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is 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 be understood by people with ordinary skills in the field to which the present invention belongs. The words "first", "second" and similar words used in the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. "Include" or "comprise" and similar words mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0063] Example:

[0064] See also Figure 1 , the present invention provides a technical solution:

[0065] A method for early warning of surrounding rock support of a dark tunnel, comprising the following specific steps:

[0066] Step 1: Deploy geological radars on the walls and vaults on both sides of the tunnel section, set the geological radars deployed in the unsupported tunnel section as the first type of sensor, and set the geological radars deployed in the supported tunnel section as the second type of sensor, and obtain the reflected wave data of all geological radars.

[0067] In this embodiment, 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 on both sides of the tunnel section are on the same horizontal plane, and the spacing between all the geological radars on the walls on both sides is also the same, and the spacing is calibrated as k c , and k c =1.5*k d .

[0068] When laying out the geological radar, determine the starting and ending positions of the tunnel section where the geological radar needs to be laid out, including sections without completed support and sections with completed support. According to the support status of the tunnel, the geological radar in the tunnel section without completed support is set as the first type of sensor, and the geological radar in the tunnel section with completed support is set as the second type of sensor. When laying out the geological radar in the center of the vault, ensure that it is aligned with the center line of the tunnel.

[0069] When installing geological radar on the walls on both sides of the tunnel, it is necessary to ensure that the installation height is consistent. Although the structures and environmental conditions of the walls on both sides may be different, the installation height and position of the radar equipment should be consistent on the left and right sides to ensure the symmetry and consistency of detection.

[0070] The side walls of the tunnel are vertical surfaces, while the vault is an arc-shaped or semicircular structure. The shape of the vault makes it different from the side walls in terms of force and geological characteristics. The vault of the tunnel usually bears a large load from above, especially the gravity and pressure from the upper strata. This concentrated force may cause displacement, settlement, cracks and other potential problems in the vault area. Therefore, the vault requires more intensive monitoring to capture possible structural changes in time, so the vault radar is more densely deployed, so the geological radar of the vault is more densely deployed, that is, the spacing is smaller.

[0071] Step 2: Based on the reflected wave data obtained from 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.

[0072] In this embodiment, each geological radar starts to emit detection waves and starts to record data at the same time point. The time when the detection wave is started to be emitted is calibrated as time zero as a 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:

[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 geological radars to emit detection waves at the same time can ensure the synchronization of the data. The time when the detection waves are emitted is marked as zero time, providing a unified time reference point. The timestamps of all data can be calculated for this reference point, thereby simplifying the timing analysis and ensuring that the detection waves emitted by all geological radars have the same frequency and amplitude, which helps to eliminate differences between different devices and improve the comparability of data. This makes the reflected wave signal more consistent during analysis, allowing data obtained by different radars to be directly compared and fused.

[0076] Scan each reflected wave signal on the time axis and find the maximum value of the signal intensity. The purpose is 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 feature is more significant, which may be related to the physical characteristics 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. The square of amplitude represents the instantaneous power. The total energy of the signal is the integral of the instantaneous power over time, which represents the total amount of energy carried by the signal within a specific time range. The integration process converts the signal from zero to t max The energy within the image is accumulated, ensuring that all signal contributions are accounted for, 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 is reflected back through the geological layer or structure and received after the radar signal is sent out. The peak arrival time is directly related to the depth of the reflection surface (such as the geological layer interface, cavity or groundwater). The longer the time means the deeper the reflection surface. This is because the radar wave propagates at a fixed speed underground. The longer the propagation time, the farther the wave propagates underground. The peak arrival time can also reflect the propagation characteristics of the medium. Different materials have different electromagnetic wave propagation speeds. By analyzing the reflection 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 that the reflecting surface is relatively smooth and flat. If the signal amplitude is small, it may indicate that the radar wave has encountered a large attenuation during the propagation process. This 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, not just the peak value at a single moment. This reflects the overall characteristics of the reflecting surface, including its reflection capability, surface area, and the propagation effect of radar waves in the area. A higher energy value may mean that the reflecting surface is very significant, such as underground cavities, strong discontinuous interfaces, etc.; lower energy may mean that the radar wave has been scattered multiple times or the reflecting surface is more dispersed, resulting in less energy reflected back.

[0081] 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 first type of sensors on the walls on both sides and the vault is:

[0082] 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:

[0083]

[0084] 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 .

[0085] 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:

[0086]

[0087] 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 .

[0088] 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 sensors on the walls on both sides and the vault is as follows:

[0089] 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:

[0090]

[0091] 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 .

[0092] 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:

[0093]

[0094] 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 top 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 among the second type of sensors, 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 .

[0095] By averaging multiple sets of reflection 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 have an overall understanding of the geological characteristics of the tunnel walls and vaults, because a single measurement value 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, which is convenient for understanding and evaluating the geological characteristics of the tunnel. The average values ​​of the vault and wall reflection waves need to be calculated separately because they have significant differences in structural morphology, stress distribution and geological environment, resulting in different reflection wave characteristics. Separate calculations can capture these differences more accurately and avoid introducing deviations by mixing data from different structural parts, thereby 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 and second sensors on the walls and the vault on both sides, generate data on the degree of deviation of the reflected waves collected by the second sensors relative to the reflected waves collected by the first sensors, and generate a difference index based on the degree of deviation data.

[0097] In an unsupported tunnel environment, the geological materials around the tunnel are still in a natural state. Since the stratum stress is not effectively managed and controlled, the materials around the tunnel may become loose, displaced, cracks may develop, and there may even be groundwater infiltration. Supported tunnels improve the geological environment around the tunnel, stabilize the stratum, and effectively manage ground stress by applying supporting structures (such as steel frames, concrete spraying layers, etc.). The role of the support system is to maintain the integrity of the stratum, reduce displacement and looseness, and increase the rigidity of the stratum and its ability to reflect radar waves.

[0098] In an unsupported environment, the rock and soil layers around the tunnel will become loose and uneven due to stress release and displacement. Due to the low density and rigidity of the material, the energy of the reflected wave will decay rapidly during propagation, resulting in a lower signal amplitude received by the sensor. The presence of looseness or cracks makes the wave propagation path more complicated, with more diffraction and scattering, resulting in a later arrival time of the wave peak relative to a supported tunnel. Due to multiple reflections and scattering, the total energy of the reflected wave is significantly reduced. When the tunnel is installed with a supporting structure, the supporting material itself has high rigidity and density. The supporting material (such as steel, concrete, etc.) has a large density and a complete structure, so the attenuation of the reflected wave is reduced, and the maximum amplitude value received by the sensor increases. The uniformity and high rigidity of the supporting material make the wave propagation more direct, the path more simplified, and the wave peak arrival time relatively early. Since the supporting material can effectively reflect radar waves, the energy loss is reduced and the total energy of the reflected wave increases.

[0099] When the reflected wave characteristics between supported tunnels and unsupported tunnels differ significantly, it indicates that the supporting material has a stronger reinforcement effect on the strata around the tunnel, changing the geological environment and the wave propagation path. On the contrary, if the difference is small, it may indicate a difference in effect between supported and unsupported, and the geological environment around the tunnel has not changed much from the unsupported state. A larger difference means that the supporting structure has a more significant effect on the tunnel, reflecting that the tunnel support is more effective in constraining the strata, redistributing stress, and making the material more compact. These changes help improve the stability of the tunnel and reduce the risk of collapse or deformation, indicating that the tunnel support system is more effective.

[0100] In this embodiment, the method for generating the difference degree index according to the deviation degree data is:

[0101] 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:

[0102]

[0103] Among them, QM w Represents the wall error index.

[0104] 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:

[0105]

[0106] Among them, GD w Represents the vault error index.

[0107] Each ratio represents the relative offset of a characteristic parameter, and the sum of the three provides a comprehensive offset measure. This form of sum can effectively integrate the offset of each characteristic parameter and provide an overall difference measure. The wall error index quantifies the difference between supported and unsupported reflection waves in wall reflection wave measurement through the relative offset 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 between supported and unsupported reflection waves in wall reflection wave measurement through the relative offset degree, and obtains the difference between vault features.

[0108] The wall error index can quantify the difference in wall reflection wave characteristics with and without support conditions. By comparing the reflection wave characteristics of the walls on both sides of the unsupported and supported tunnel sections, the impact of support on wall stability can be identified. If the wall error index is larger, it means that the maximum amplitude, peak arrival time and total energy of the wall reflection wave in the supported tunnel section are significantly improved compared with the unsupported tunnel section, indicating that the supporting structure is effective and can better reflect radar waves, indicating that the wall maintains better stability and integrity and reduces looseness and displacement. If it is smaller, it means that the difference in reflection wave characteristics between the unsupported and supported walls is not obvious, and in some cases the intensity of the reflection wave is even weakened, indicating that the support effect is not good, 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 reflection wave characteristics of the tunnel vault with and without support. By comparing the maximum amplitude value, peak arrival time and total energy of the vault, the influence of the support structure on the vault area can be evaluated. If the vault error index is large, it means that the vault of the supported tunnel section has a significant improvement in reflection wave characteristics compared to the vault of the unsupported tunnel section, indicating that the support structure at the vault is effective, the intensity of the reflection wave is enhanced, the stability of the vault is significantly improved, and the support structure can effectively manage the stress distribution of the vault. If it is small, it means that the difference in reflection wave characteristics of the vault under unsupported and supported conditions is not obvious, and in some cases the amplitude of the reflection wave is weakened, which may indicate that the support effect is not obvious, there are safety hazards in the vault, or the support structure has failed to effectively improve the stability of the vault.

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

[0111] CYz=ω1*GD w +ω2*QM w

[0112] 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.

[0113] The construction logic of the difference degree index is to comprehensively evaluate 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 the index will be explained in detail below.

[0114] When the arch error index and the wall error index are small, the difference degree index is small, and the difference between unsupported and supported is not large, which means that the better the self-support effect of the tunnel, the more stable the self-support structure of the unsupported tunnel. By combining the reflection characteristics of the arch and the wall, the overall safety of the tunnel structure can be fully reflected. This comprehensive index can provide a more comprehensive evaluation result. The purpose of setting the weight coefficient is to influence the calculation of the difference degree index according to the actual importance of the structure. The arch plays a more critical role in the overall stability of the tunnel, because the load and pressure borne by the arch directly affect the structural stability of the entire tunnel. A larger weight is set for the arch, and the normalization of the weight coefficient is ensured, so that the weight maintains a relatively reasonable proportional relationship in the calculation, ensuring the validity of the comprehensive index.

[0115] The smaller the difference index, the smaller the arch error index and the wall error index, indicating that the tunnel itself has a good support effect. Even if it has no support, the side structure is stable and can effectively reflect the good reflection wave characteristics. The larger the difference index, the larger the arch error index and the wall error index, which may have poor support effects or structural problems. By constructing the difference index, the reflection wave characteristics of the arch and the wall can be effectively integrated to quantify the overall stability of the tunnel structure under support conditions. 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 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.

[0117] In this embodiment, after performing 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, and a modulus calculation is performed on each complex sequence to obtain the amplitude of each frequency component, and 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.

[0118] After fast Fourier transform, the reflected wave data is converted from time domain to frequency domain, and the main frequency and frequency bandwidth data of the reflected wave can be extracted. What is obtained after 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 with the most concentrated energy in the signal. The frequency corresponding to the maximum amplitude value found in the reflected wave data is the main frequency of the signal.

[0119] The main frequency is the frequency component with the most concentrated energy in the reflected wave signal. For unsupported tunnels, the main frequency can reflect the stiffness and density of the tunnel sidewall's own structural material. When the material of the tunnel sidewall is relatively uniform, the main frequency is usually relatively stable. If the main frequency at different locations varies greatly, it may mean that there are large differences in the sidewall material 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 means 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 the material has discontinuity, heterogeneity or a multi-layer structure, resulting in a complex waveform and energy distribution in a wider frequency range.

[0120] If the material distribution of the tunnel's side walls is uniform, the main frequency should usually be close to the same at different locations, and the bandwidth should be relatively narrow, indicating that the material properties are relatively consistent and the fluctuations are small. If the main frequencies are significantly different at different measuring points, or the frequency bandwidth changes significantly, this may indicate the unevenness of the supporting structure. For unsupported tunnels, uniform material means that when there is no support, the support itself is relatively uniformly stressed, and there will be no local stress. It is not easy to have risks such as falling blocks and local collapse due to uneven bearing capacity.

[0121] Furthermore, 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:

[0122]

[0123] 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;

[0124] 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:

[0125]

[0126] 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 . .

[0127] Step 5: Based on the average value of the main frequency data and 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 frequency bandwidth data obtained by the first type of sensors, a stability uniformity index of the unsupported tunnel section is generated.

[0128] In this embodiment, the calculation formula of the stability uniformity index of the unsupported tunnel section is:

[0129]

[0130] 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.

[0131] The stability uniformity index is a parameter that measures the structural uniformity of a tunnel when it is not supported. It reflects the consistency of the structure of an unsupported tunnel section. The calculation of the index takes into account the differences in the geo-radar data of the vault and the wall, and measures the degree of discreteness of the data in the form of variance. If the deviation of the main frequency and frequency bandwidth of the vault and the wall from their average value is small, the stability uniformity index will be small, indicating that the uniformity of the tunnel's own side structure is better. On the contrary, if the deviation is large, the stability uniformity index will be large, indicating that the uniformity is poor.

[0132] When the stability uniformity index is large, it means that the main frequency and frequency bandwidth of the tunnel section's own side structure at different positions are quite different, reflecting the non-uniformity of its own side structure. This may be caused by factors such as the tunnel being located in a place with uneven geological materials. A large value may indicate that when no support is provided, there are potential safety hazards in its own support, and there may be a risk of local collapse or falling.

[0133] When the stability uniformity index is small, it means that the main frequency and frequency bandwidth data of the tunnel section's own side wall structure at different positions are relatively consistent, reflecting the good uniformity of the overall structure, which means that the overall performance of the tunnel's own side wall structure is relatively stable, without obvious weaknesses or discontinuities. A smaller support uniformity index value indicates that the supporting structure of the tunnel section is healthier and the overall structural performance is more reliable. The supporting structure at the vault is more critical, so the vault has a larger weight, followed by the wall with a smaller weight.

[0134] 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.

[0135] In this embodiment, the difference degree index and the stability uniformity index are comprehensively analyzed and processed to construct a risk analysis model, and the specific formula for the support risk index of the tunnel section without completed support is obtained as follows:

[0136]

[0137] 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 .

[0138] The overall values ​​of the stability uniformity index and the difference degree index are comprehensively evaluated by taking the average of the square sum. The logarithmic operation compresses the growth rate of the results, especially when the stability uniformity index and the difference degree index increase, this part of the results will no longer grow linearly. If the stability uniformity index and the difference degree index are both large, it means that the unsupported tunnel has poor self-support effect and there are large structural fluctuations, so the support risk index will increase. When the stability uniformity index and the difference degree index are small, the support risk index will become smaller, 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 nonlinear effect is enhanced through exponential operation. The denominator CYz+ZJz+∈ is used for normalization, so that when the two indexes are close, the change of the exponential part is relatively smooth. The exponential operation amplifies the interactive effect of the support uniformity index and the difference degree index. When both indexes are high, the result of this part will increase significantly, which means that the stability of the support effect itself is poor, and the structure may be uneven and unstable. On the contrary, if both indexes are small, the exponential part will tend to 1, and the amplification effect on the result is not obvious.

[0140] Introducing a smaller ∈ can effectively prevent the denominator from being 0, thereby ensuring the stability and effectiveness of the formula. The value of ∈ should be small enough to ensure that it has little impact on the result in actual calculations. Select range 10 ―9 to 10 ―6 It is ensured that the value of ∈ does not significantly affect the calculation of the support uniformity index and the heterogeneity index, especially when these values ​​are also small.

[0141] The support risk index is a quantitative indicator that reflects the stability of the side wall support system of an unsupported tunnel. It constructs a formula that includes a nonlinear amplification effect based on the interaction between the difference degree index and the stability uniformity index. A larger support risk index means that the tunnel's own support structure may be unstable or have structural weaknesses, and its own support effect is poor; while a smaller support risk index means that its own support structure is more uniform and stable, and its support effect is better. The support effect index can accurately reflect the tunnel's own support effect and provide a basis for safety assessment and support warning.

[0142] When judging whether to issue a support warning, if ZXz ≥ ZXy, a risk warning will be issued for the tunnel section that has not completed the support, otherwise no warning will be 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 there are in the support structure itself, and the worse the support effect. ZXy is a pre-set threshold, which indicates the maximum instability or risk level that the support structure can accept, which 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 means that the support risk index exceeds the set safety threshold, which means that the stability of the tunnel's own support structure may have reached an unacceptable level. Therefore, it is necessary to issue an insufficient support warning to remind relevant engineering personnel to pay attention to the risk of local collapse or falling of the tunnel.

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

[0145] The above formulas are all dimensionless and take their numerical values for calculation. The formulas are 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 formulas 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 in this article 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. 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] As described above, only the specific implementation manners of this application are provided, but the protection scope of this application is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed in this application, and all should be covered by the protection scope of this 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 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 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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