Strain type rockburst occurrence section and grade early warning method for different open type TBM (tunnel boring machine) sections of tunnel

Abstract

The invention discloses an occurrence section and grade early warning method for strain type rockburst of different open type TBM sections of a tunnel, and relates to the technical field of rockburst risk early warning. Comprising the following steps: dividing an unexcavated area in front of a tunnel face into early warning units along a tunnel axis; microseismic monitoring information in the early warning unit is collected and processed; the proportion of the shear fracture number before excavation of the early warning unit is calculated, and whether the potential rockburst type in the early warning unit is strain type rockburst or not is judged; calculating a compression energy-depth index, micro-seismic activity intensity and the maximum change amplitude of the micro-seismic activity intensity in the early warning unit in the excavation process; the occurrence section of the strain type rockburst is judged and identified; early warning indexes of strain type rockburst of different open-type sections of the tunnel are obtained, and a case sample library of strain type rockburst of different sections is established; intelligent early warning models of strain type rockburst of different sections are established; and calculating an early warning index in the early warning unit, and obtaining an early warning rockburst grade. According to the method, the occurrence section of strain type rockburst of the open-type TBM tunnel is identified.

Description

Technical Field

[0001] This invention relates to the field of rockburst risk early warning technology, and more specifically to a method for early warning of the occurrence sections and levels of strain-type rockbursts in different open TBM sections of tunnels. Background Technology

[0002] Based on the structural composition, construction methods, and personnel and equipment distribution characteristics of open-face TBMs, the excavated tunnel section can be divided into three zones: the shield zone, the main beam zone, and the area behind the main beam. The shield zone roughly extends from the tunnel face to a distance of one tunnel diameter behind it; the main beam zone roughly extends from one to three tunnel diameters behind the tunnel face; and the area behind the main beam roughly extends three tunnel diameters behind the tunnel face. The corresponding strain-type rockbursts occurring in these three zones are: shield zone-strain-type rockburst, main beam zone-strain-type rockburst, and main beam rear-strain-type rockburst. The impact of strain-type rockbursts differs across zones. For example, when all rockbursts are of medium intensity, strain-type rockbursts occurring in the main beam zone and behind the main beam may cause severe equipment damage and threaten the safety of construction personnel. However, due to the shield's protective effect, strain-type rockbursts in the shield zone are unlikely to pose a threat to personnel and equipment. Therefore, it is necessary to conduct early warning studies for strain-type rockbursts in different zones.

[0003] In open-face TBM tunnels, the early warning requirements for strain-type rockbursts differ across different sections. For strain-type rockbursts in the shield zone, which occur earlier, early warning results need to be issued before excavation of the potential rockburst area to facilitate timely on-site control strategies. For strain-type rockbursts in the main beam zone, which occur relatively later, early warning results can be issued after a period of lag between the excavation of the warning unit and the actual rockburst. Therefore, early warning for strain-type rockbursts in the main beam zone can be developed based on multi-source information, taking into account the geological characteristics and high-stress failure characteristics of the exposed surrounding rock. Strain-type rockbursts occur latest in the rear of the main beam zone, allowing more time to acquire relevant multi-source information, thereby effectively optimizing the rockburst early warning effect.

[0004] Microseismic monitoring is the most effective and widely used method for rockburst monitoring. Based on microseismic monitoring, scholars have proposed many methods for predicting the spatiotemporal occurrence of rockbursts, including a time-delay type rockburst spatiotemporal early warning method for tunnel construction (CN110568477A), a classification-regression cascaded multi-task intelligent early warning method for rockbursts (CN118296936A), and an instantaneous rockburst time early warning method applicable to drill-and-blast tunnel excavation (CN117092692). This research has relatively accurately predicted potential rockburst areas and rockburst levels, as well as provided short-term early warnings of rockburst times. However, it has not considered the occurrence characteristics and early warning requirements of rockbursts in different sections of open-face TBM tunnels, and has not yet achieved the identification of strain-type rockburst occurrence sections or early warning of rockburst levels.

[0005] Therefore, proposing a method for early warning of the occurrence zone and level of strain-type rockburst in different open TBM sections of tunnels to solve the difficulties of existing technologies is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0006] In view of this, the present invention provides a method for early warning of the occurrence zone and level of strain-type rockburst in different open TBM sections of tunnels, in order to solve the technical problems existing in the prior art.

[0007] To achieve the above objectives, the present invention provides the following technical solution: A method for early warning of the occurrence and severity of strain-type rockbursts in different open-type TBM sections of tunnels, including the following steps: S1. The unexcavated area in front of the tunnel face is designated along the tunnel axis as... L x × L y × L z Early warning unit; S2. Collect and process microseismic monitoring information within the early warning unit; S3. Calculate the percentage of shear fractures before excavation of the early warning unit. S ,like S ≤ S SR If so, the potential rockburst type within the early warning unit is determined to be strain-type rockburst; S4. Calculate the compression energy-depth index during the excavation process within the early warning unit. Strong microseismic activity Spend and the maximum variation in the intensity of microseismic activity ; S5. Calculate the maximum compressible energy-depth index before the excavation of the early warning unit. Value, during the excavation process L MAI Values ​​are used to identify the areas where strain-type rockbursts occur; S6. Obtain early warning indicators for strain-type rockbursts in different open TBM sections of the tunnel, and establish a case sample library of strain-type rockbursts in different sections; S7. Establish intelligent early warning models for strain-type rockbursts in different sections; S8. Calculate the early warning indicators in the early warning unit, input the corresponding intelligent early warning model of the occurrence section, and obtain the early warning rockburst level.

[0008] Optional, in S1 L x Determined by the average daily tunnel advance or the advance per shift. L y , Lz pass y , z The distribution characteristics of microseismic events in different directions were determined.

[0009] Optional, in S3 S SR It is by using the early warning unit S The value is related to the early warning unit where existing strain-type rockburst, strain-structure plane slip-type rockburst, and fracture-type rockburst cases are located. S The threshold is obtained by comparing the values.

[0010] Optional, compression energy-depth index in S4 The formula for calculating the value is: ; in, E The energy released by accumulated microseismic events is expressed in J. For the first i The energy released by a microseismic event, expressed in J; For the first i The distance of each microseismic event from the center of the tunnel is expressed in meters. Microseismic activity intensity The calculation formula is: ; in, , The first The number of microseismic events and the energy released by microseismic events accumulated during the excavation of each excavation section; , They are respectively and The coefficient; Maximum range of change The calculation formula is: ; in, For the 0th~ i During each excavation section The maximum value.

[0011] Optionally, in S5, the maximum compressible energy-depth index before excavation of the early warning unit is calculated. Value, during the excavation process L MAI The specific details for identifying the occurrence zone of strain-type rockbursts are as follows: Peak threshold and The magnitude is determined by the excavation process of the early warning unit. Value and The value was determined by comparing it with the corresponding indicators during the excavation process of the early warning unit where existing cases of shield zone-strain rockburst, main beam zone-strain rockburst, and main beam rear-strain rockburst were located; The maximum compressible energy before excavation of the early warning unit - depth index Value, during the excavation process L MAI The value is compared with the corresponding threshold to identify the occurrence zone of strain-type rockburst.

[0012] Optionally, the case sample library in S6 is divided into the shield area-strain rockburst case sample library, the main beam area-strain rockburst case sample library, and the main beam rear-strain rockburst case sample library; The early warning indicators for shield zone-strain type rockburst include: cumulative number of microseismic events, cumulative microseismic release energy, cumulative microseismic apparent volume, instantaneous number of microseismic events, instantaneous microseismic release energy, and instantaneous microseismic apparent volume within the early warning unit; The early warning indicators for strain-type rockburst in the main beam area include: the cumulative number of microseismic events, the cumulative microseismic energy release, the cumulative microseismic apparent volume, the number of instantaneous microseismic events, the instantaneous microseismic energy release and the instantaneous microseismic apparent volume, the mean value of the instantaneous rockburst crater depth and the standard deviation of the penetration index. The early warning indicators for post-strain rockburst of the main beam include: the cumulative number of microseismic events, the cumulative microseismic release energy, the cumulative microseismic apparent volume, the number of time-dependent microseismic events, the time-dependent microseismic release energy and the time-dependent microseismic apparent volume, the mean value of the tail depth of the instantaneous rockburst crater, and the standard deviation of the penetration index.

[0013] Optionally, the specific content of establishing intelligent early warning models for strain-type rockbursts in different sections in S7 is as follows: 70% of the sample library of strain-type rockburst cases in different sections was used as training samples and 30% as test samples. The intelligent early warning model of strain-type rockburst in different sections was trained and tested using the sample library of strain-type rockburst cases in different sections.

[0014] Optionally, in S8, the early warning indicators in the early warning unit are calculated, and the corresponding intelligent early warning model for the affected area is input to obtain the specific details of the early warning rockburst level: The early warning indicators are dynamically calculated by combining changes in microseismic activity during the excavation of open-face TBM tunnels, and the early warning rockburst level is updated.

[0015] As can be seen from the above technical solution, compared with the prior art, the present invention discloses a method for early warning of the occurrence sections and levels of strain-type rockbursts in different open-type TBM sections of tunnels, and its beneficial effects are as follows: Microseismic information can be used to identify strain-type rockburst occurrence zones in advance. Microseismic early warning indicators can be used to achieve rapid early warning of strain-type rockburst in the shield zone. Multi-source parameter early warning of strain-type rockburst in the main beam zone and behind the main beam can be achieved through microseismic information, real-time rockburst information and TBM parameter information. The above methods provide a scientific basis for the timing of prevention and control of strain-type rockburst in open TBM tunnels and the design of prevention and control measures parameters. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0017] Figure 1 This is an overall flowchart of the method for early warning of the occurrence zone and level of strain-type rockburst in different open-type TBM sections of the tunnel provided in an embodiment of the present invention. Figure 2 A graph showing the calculation results of the percentage S of shear fractures before excavation in the early warning unit where different types of rockbursts are located, provided for an embodiment of the invention; Figure 3 The maximum value before excavation of the early warning unit for different sections of strain-type rockburst provided in the embodiments of the invention. CEDI Value results graph; Figure 4 The different sections of strain-type rockburst warning unit provided in the embodiments of the invention are during the excavation process. L MAI Value results graph; Figure 5 A VAE model diagram of shield zone-strain type rockburst level early warning provided for embodiments of the invention; Figure 6 VTP-net model diagram of strain-type rockburst level early warning for main beam area provided for embodiments of the invention; Figure 7 The fracturing mechanism before excavation of the early warning unit provided in the embodiments of the invention and CEDI Value evolution feature map; Figure 8 A spatial distribution characteristic map of microseismic events during the excavation process of the early warning unit provided in the embodiments of the invention; Figure 9 The early warning unit provided in the embodiments of the invention is used during the excavation process. MAI i and S MAIi Evolutionary feature map of values; Figure 10A spatial distribution diagram of microseismic activity within the early warning unit during the face advancement process, provided for an embodiment of the invention; Figure 11 The main beam area strain-type minor rockburst occurred at azimuth 12 to 1 in the region K22+861.8~K22+864.2 provided in the embodiment of the invention. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] See Figure 1 As shown, this invention discloses a method for early warning of the occurrence zones and levels of strain-type rockbursts in different open-type TBM sections of tunnels, including the following steps: S1. The unexcavated area in front of the tunnel face is designated along the tunnel axis as... L x × L y × L z A warning unit measuring (length × width × height); S2. Collect and process microseismic monitoring information within the early warning unit; S3. Calculate the percentage of shear fractures before excavation of the early warning unit. S ,like S ≤ S SR If so, the potential rockburst type within the early warning unit is determined to be strain-type rockburst; S4. Calculate the compression energy-depth index during the excavation process within the early warning unit. Strong microseismic activity Spend and the maximum variation in the intensity of microseismic activity ; S5. Calculate the maximum compressible energy-depth index before the excavation of the early warning unit. Value, during the excavation process L MAI Values ​​are used to identify the areas where strain-type rockbursts occur; S6. Obtain early warning indicators for strain-type rockbursts in different open TBM sections of the tunnel, and establish a case sample library of strain-type rockbursts in different sections; S7. Establish intelligent early warning models for strain-type rockbursts in different sections; S8. Calculate the early warning indicators in the early warning unit, input the corresponding intelligent early warning model of the occurrence section, and obtain the early warning rockburst level.

[0020] Furthermore, in S1 L x Determined by the average daily tunnel advance or the advance per shift. L y , L z pass y , z The distribution characteristics of microseismic events in different directions were determined.

[0021] Furthermore, in S3 S SR It is by using the early warning unit S The value is related to the early warning unit where existing strain-type rockburst, strain-structure plane slip-type rockburst, and fracture-type rockburst cases are located. S The threshold is obtained by comparing the values.

[0022] Furthermore, the compression energy-depth index in S4 The formula for calculating the value is: ; in, E The energy released by accumulated microseismic events is expressed in J. For the first i The energy released by a microseismic event, expressed in J; For the first i The distance of each microseismic event from the center of the tunnel is expressed in meters. Microseismic activity intensity The calculation formula is: ; in, , The first The number of microseismic events and the energy released by microseismic events accumulated during the excavation of each excavation section; , They are respectively and The coefficient; Specifically, , The values ​​are 0.4 and 0.6 respectively.

[0023] Maximum range of change The calculation formula is: ; in, For the 0th~ i During each excavation section The maximum value.

[0024] Furthermore, in S5, the maximum compressible energy-depth index before excavation of the early warning unit is calculated. Value, during the excavation process L MAI The specific details for identifying the occurrence zone of strain-type rockbursts are as follows: Peak threshold and The magnitude is determined by the excavation process of the early warning unit. Value and The value was determined by comparing it with the corresponding indicators during the excavation process of the early warning unit where existing cases of shield zone-strain rockburst, main beam zone-strain rockburst, and main beam rear-strain rockburst were located; The maximum compressible energy before excavation of the early warning unit - depth index Value, during the excavation process L MAI The value is compared with the corresponding threshold to identify the occurrence zone of strain-type rockburst.

[0025] Specifically, definition L MAI The indicator is to meet Peak value greater than Threshold, and Less than The threshold condition is the ratio of the distance from the center of the early warning unit to the tunnel face to the tunnel diameter.

[0026] Furthermore, the case sample library in S6 is divided into the shield area-strain rockburst case sample library, the main beam area-strain rockburst case sample library, and the main beam rear-strain rockburst case sample library; The early warning indicators for shield zone-strain type rockburst include: cumulative number of microseismic events, cumulative microseismic release energy, cumulative microseismic apparent volume, instantaneous number of microseismic events, instantaneous microseismic release energy, and instantaneous microseismic apparent volume within the early warning unit; The early warning indicators for strain-type rockburst in the main beam area include: the cumulative number of microseismic events, the cumulative microseismic energy release, the cumulative microseismic apparent volume, the number of instantaneous microseismic events, the instantaneous microseismic energy release and the instantaneous microseismic apparent volume, the mean value of the instantaneous rockburst crater depth and the standard deviation of the penetration index. The early warning indicators for post-strain rockburst of the main beam include: the cumulative number of microseismic events, the cumulative microseismic release energy, the cumulative microseismic apparent volume, the number of time-dependent microseismic events, the time-dependent microseismic release energy and the time-dependent microseismic apparent volume, the mean value of the tail depth of the instantaneous rockburst crater, and the standard deviation of the penetration index.

[0027] Furthermore, the specific content of establishing intelligent early warning models for strain-type rockbursts in different sections in S7 is as follows: 70% of the sample library of strain-type rockburst cases in different sections was used as training samples and 30% as test samples. The intelligent early warning model of strain-type rockburst in different sections was trained and tested using the sample library of strain-type rockburst cases in different sections.

[0028] Furthermore, in S8, the early warning indicators in the early warning unit are calculated and input into the intelligent early warning model of the corresponding occurrence section to obtain the specific content of the early warning rockburst level: The early warning indicators are dynamically calculated by combining changes in microseismic activity during the excavation of open-face TBM tunnels, and the early warning rockburst level is updated.

[0029] Example 1

[0030] TBM I, TBM II, and TBM III tunnels have circular cross-sections with diameters of 7.8m, 7.8m, and 7.0m respectively, and total lengths of 15.3km, 15.2km, and 20.1km respectively. All three tunnels were excavated using open-face TBMs. The rock composition of the three tunnels is primarily granite. During the construction of the three open-face TBM tunnels, the average advance per shift was approximately 1-2 [units of measurement missing]. D ( D (Indicates the tunnel diameter), which can be taken as... L x =1.5 D Invention patent CN117452497A provides a method for predicting fracture-type rockburst in deeply buried TBM tunnels based on microseismic information. The embodiments described have similar engineering geological conditions, and after reference, the following methods can be adopted. L y ∈[-3D, +3D], L z ∈[-3 D +3 D "+" indicates the positive direction of the corresponding coordinate axis, and "-" indicates the negative direction of the corresponding coordinate axis.

[0031] See Figure 2 The figure shown is a graph illustrating the calculated percentage (S) of shear fractures in early warning units for different types of rockbursts before excavation. By comparison, the threshold percentage of shear fractures in early warning units for strain-type rockbursts before excavation is determined. S SR =5%.

[0032] See Figure 3 As shown, this represents the maximum stress before excavation of the early warning unit where strain-type rockbursts occur in different sections. CEDI Value result diagram. After comparison, the maximum value before excavation of the early warning unit where the shield zone-strain type is located is... CEDI Value ≥ 2, the maximum value before excavation of the main beam area and the strain-type warning unit located behind the main beam. CEDI Value < 2. In addition, it should be noted that, based on statistical analysis, the three open-type TBM tunnels... L MAI The specific definition is to satisfy " Peak value > 7, and When the condition is <50%, the ratio of the distance from the center of the early warning unit to the tunnel face to the tunnel diameter. Figure 4 For different sections of strain-type rockburst during the excavation process of the early warning unit L MAI Value results. After comparison, during the excavation of the early warning unit where the shield area and the main beam are located (strain type),... L MAI <1, During the excavation of the early warning unit in the main beam area - strain type L MAI ≥1.

[0033] In summary, the identification method for strain-type rockburst occurrence zones in the above three open-type TBM tunnels is as follows: ① Shield zone - strain-type rockburst: maximum before excavation of the early warning unit. CEDI ≥2, or simultaneously present during the excavation process L MAI <1; ② Main beam area - strain-type rockburst: maximum before excavation of the early warning unit CEDI <2, during the excavation process L MAI ≥1; ③ Main beam post-strain type rockburst: maximum before excavation of the early warning unit CEDI <2, during the excavation process L MAI <1.

[0034] Based on the MixUp data augmentation method, interpolation enhancement is performed on rockburst data of different levels in different sections to increase the diversity of rockburst data. Then, using the cumulative number of microseismic events, the cumulative logarithm of microseismic energy release, the cumulative apparent volume of microseismic events, the number of instantaneous microseismic events, the instantaneous microseismic energy release, and the instantaneous apparent volume of microseismic events within the early warning unit as early warning indicators, a VAE model for shield zone-strain type rockburst level early warning is constructed. (See [link to relevant documentation]). Figure 5 As shown; Using the cumulative number of microseismic events, cumulative logarithmic microseismic energy release, cumulative apparent volume of microseismic events, instantaneous number of microseismic events, instantaneous microseismic energy release, instantaneous apparent volume of microseismic events, mean value of instantaneous rockburst crater depth, and variance of penetration index as early warning indicators, and employing a Domain-Adversarial Neural Network (DANN) as the transfer framework, a VTP-net (Variational-Transfer-Personalized Network) model for early warning of strain-type rockburst levels in the main beam area is constructed. (See [link to relevant documentation]). Figure 6As shown in the figure, the shield zone-strain rockburst is the source domain for transfer learning, and the main beam zone-strain rockburst is the target domain. Finally, using the cumulative number of microseismic events, the cumulative logarithmic microseismic energy release, the cumulative apparent volume of microseismic events, the number of time-dependent microseismic events, the time-dependent microseismic energy release, the time-dependent microseismic apparent volume, the mean of the tail depth of the instantaneous rockburst crater, and the variance of the penetration index as early warning indicators, and referring to the establishment method of the VTP-net model for the main beam zone-strain rockburst level early warning, a VTP-net model for the main beam rear-strain rockburst level early warning is constructed.

[0035] The following describes the application of the strain-type rockburst occurrence zone identification and rockburst level early warning method provided by this invention in the subsequent excavation section of the TBMⅡ tunnel: At 12:00 on July 30, 2023, when the tunnel face reached K22+860, the surrounding rock was generally dry and intact. Based on the method for determining early warning units in open-face TBM tunnels, the chainage range of the early warning units was determined to be K22+860~K22+872. Analysis of the microseismic rupture mechanism within the early warning units revealed that all microseismic events were tensional ruptures, indicating that the potential rockburst type in this area is strain-type rockburst. Figure 7 As shown. The intelligent rockburst early warning system calculates in real time the value of the rockburst before the excavation of the early warning unit. CEDI For details on value evolution, please refer to [link / reference]. Figure 7 As shown in the figure. It can be seen that the maximum [value] before excavation of the early warning unit [is...]. CEDI A value of 0.49 < 2 indicates that the possible occurrence zone of strain-type rockburst within the early warning unit is the main beam area or behind the main beam.

[0036] At 10:00 AM on July 31st, when the tunnel face reached K22+874, some micro-vibrations occurred within the early warning unit, lagging behind the tunnel face by a certain distance. However, the overall number of events was small and there was no obvious concentrated trend. Figure 8 As shown. The intelligent rockburst early warning system calculates and displays in real time the early warning unit during tunnel excavation. MAI i and S MAIi Evolutionary characteristics such as Figure 9 As shown. It can be seen that, MAI i The value shows a fluctuating trend, with its maximum value being 3.02 < 7. Therefore, L MAI A value greater than 1 indicates that the main beam area is the possible location for strain-type rockbursts within the early warning unit.

[0037] At 10:00 AM on July 31st, after the intelligent rockburst early warning system identified a potential strain-type rockburst risk in the main beam area within the early warning unit, further early warning parameter indicators within the unit were extracted (see Table 1) and used as input parameters into the established VTP-net model for main beam area strain-type rockburst level early warning. The output rockburst level early warning result was: no rockburst.

[0038] Table 1. Warning parameter information within the warning unit

[0039] During subsequent tunnel excavation, the intelligent rockburst early warning system continuously issued warnings for the area from K22+859 to K22+871, constantly updating the warning results. From 10:00 on July 31st to 18:00 on August 1st, during the advancement of the tunnel face, micro-seismic events continued to occur with a lag within the warning area, showing a tendency to cluster and form nuclei, such as... Figure 10 As shown in Table 1, at 18:00 on August 1st, the intelligent rockburst early warning system automatically calculated the early warning parameter indicators within the early warning unit and input them into the established VTP-net model for main beam area-strain type rockburst level early warning. The output rockburst level early warning result was: minor rockburst.

[0040] At 23:04 on August 1, 2023, a minor strain-type rockburst occurred in the area from K22+861.8 to K22+864.2, at the 12:00 to 1:00 azimuth. The rockburst was accompanied by a crisp crackling sound and rock fragment ejection, ultimately forming a long, shallow, elongated crater with a depth of 0.19m. Figure 11 As shown, the center of the crater lagged behind the working face by 22m when the rockburst occurred. There were no obvious structural surfaces within the crater, which indicates a strain-type rockburst in the main beam area, consistent with the early warning results.

[0041] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0042] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for early warning of the occurrence zone and level of strain-type rockburst in different open-type TBM sections of tunnels, characterized in that, Includes the following steps: S1. The unexcavated area in front of the tunnel face is designated along the tunnel axis as... L x × L y × L z Early warning unit; S2. Collect and process microseismic monitoring information within the early warning unit; S3. Calculate the percentage of shear fractures before excavation of the early warning unit. S ,like S ≤ S SR If so, the potential rockburst type within the early warning unit is determined to be strain-type rockburst; S4. Calculate the compression energy-depth index during the excavation process within the early warning unit. Strong microseismic activity Spend and the maximum variation in the intensity of microseismic activity ; S5. Calculate the maximum compressible energy-depth index before the excavation of the early warning unit. Value, during the excavation process L MAI Values ​​are used to identify the areas where strain-type rockbursts occur; S6. Obtain early warning indicators for strain-type rockbursts in different open TBM sections of the tunnel, and establish a case sample library of strain-type rockbursts in different sections; S7. Establish intelligent early warning models for strain-type rockbursts in different sections; S8. Calculate the early warning indicators in the early warning unit, input the corresponding intelligent early warning model of the occurrence section, and obtain the early warning rockburst level.

2. The method for early warning of the occurrence section and level of strain-type rockburst in different open-type TBM sections according to claim 1, characterized in that, S1 L x Determined by the average daily tunnel advance or the advance per shift. L y , L z pass y , z The distribution characteristics of microseismic events in different directions were determined.

3. The method for early warning of the occurrence section and level of strain-type rockburst in different open-type TBM sections according to claim 1, characterized in that, S3 S SR It is by using the early warning unit S The value is related to the early warning unit where existing strain-type rockburst, strain-structure plane slip-type rockburst, and fracture-type rockburst cases are located. S The threshold is obtained by comparing the values.

4. The method for early warning of the occurrence section and level of strain-type rockburst in different open-type TBM sections according to claim 1, characterized in that, S4 Compression Energy-Depth Index The formula for calculating the value is: ； in, E The energy released by accumulated microseismic events is expressed in J. For the first i The energy released by a microseismic event, expressed in J; For the first i The distance of each microseismic event from the center of the tunnel is expressed in meters. Microseismic activity intensity The calculation formula is: ； in, , The first The number of microseismic events and the energy released by microseismic events accumulated during the excavation of each excavation section; , They are respectively and The coefficient; Maximum range of change The calculation formula is: ； in, For the 0th~ i During each excavation section The maximum value.

5. The method for early warning of the occurrence zone and level of strain-type rockburst in different open-type TBM sections according to claim 1, characterized in that, S5 calculates the maximum compressible energy-depth index before the excavation of the early warning unit. Value, during the excavation process L MAI The specific details for identifying the occurrence zone of strain-type rockbursts are as follows: Peak threshold and The magnitude is determined by the excavation process of the early warning unit. Value and The value was determined by comparing it with the corresponding indicators during the excavation process of the early warning unit where existing cases of shield zone-strain rockburst, main beam zone-strain rockburst, and main beam rear-strain rockburst were located; The maximum compressible energy before excavation of the early warning unit - depth index Value, during the excavation process L MAI The value is compared with the corresponding threshold to identify the occurrence zone of strain-type rockburst.

6. The method for early warning of the occurrence zone and level of strain-type rockburst in different open-type TBM sections according to claim 5, characterized in that, The case sample library in S6 is divided into the shield area-strain type rockburst case sample library, the main beam area-strain type rockburst case sample library, and the main beam rear-strain type rockburst case sample library; The early warning indicators for shield zone-strain type rockburst include: cumulative number of microseismic events, cumulative microseismic release energy, cumulative microseismic apparent volume, instantaneous number of microseismic events, instantaneous microseismic release energy, and instantaneous microseismic apparent volume within the early warning unit; The early warning indicators for strain-type rockburst in the main beam area include: the cumulative number of microseismic events, the cumulative microseismic energy release, the cumulative microseismic apparent volume, the number of instantaneous microseismic events, the instantaneous microseismic energy release and the instantaneous microseismic apparent volume, the mean value of the instantaneous rockburst crater depth and the standard deviation of the penetration index. The early warning indicators for post-strain rockburst of the main beam include: the cumulative number of microseismic events, the cumulative microseismic release energy, the cumulative microseismic apparent volume, the number of time-dependent microseismic events, the time-dependent microseismic release energy and the time-dependent microseismic apparent volume, the mean value of the tail depth of the instantaneous rockburst crater, and the standard deviation of the penetration index.

7. The method for early warning of the occurrence zone and level of strain-type rockburst in different open-type TBM sections according to claim 1, characterized in that, The specific content of establishing intelligent early warning models for strain-type rockbursts in different sections in S7 is as follows: 70% of the sample library of strain-type rockburst cases in different sections was used as training samples and 30% as test samples. The intelligent early warning model of strain-type rockburst in different sections was trained and tested using the sample library of strain-type rockburst cases in different sections.

8. The method for early warning of the occurrence section and level of strain-type rockburst in different open-type TBM sections according to claim 1, characterized in that, In S8, the early warning indicators in the early warning unit are calculated and input into the intelligent early warning model of the corresponding occurrence section to obtain the specific content of the early warning rockburst level: The early warning indicators are dynamically calculated by combining changes in microseismic activity during the excavation of open-face TBM tunnels, and the early warning rockburst level is updated.

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