Deep and long tunnel water inrush critical value analysis method

Abstract

The invention discloses a deep and long tunnel water inrush critical value analysis method, and relates to the technical field of tunnel engineering.The deep and long tunnel water inrush critical value analysis method comprises the steps that engineering geological parameters and hydrogeological parameters in front of a tunnel face are obtained; based on the engineering geological parameters and the hydrogeological parameters, constructing a water inrush critical value analysis model to calculate a water inrush critical pressure value; real-time water pressure in front of the tunnel face is monitored, and a real-time water pressure monitoring value is obtained; the real-time water pressure monitoring value is compared with the water inrush critical pressure value, and the water inrush risk level is evaluated according to the comparison result; and according to the water inrush risk level, generating and outputting a construction early warning and risk prevention and control instruction. According to the method, the engineering geological parameters and the hydrogeological parameters are acquired, the water inrush critical value analysis model is constructed to calculate the water inrush critical pressure value, the real-time water pressure is monitored, the risk level is compared and evaluated, and the prevention and control instruction is generated, so that the problems of insufficient parameter reliability and untimely risk evaluation in the prior art are solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of tunnel engineering, in particular to a deep and long tunnel water inrush critical value analysis method. BACKGROUND

[0002] With the continuous extension of tunnel engineering in the direction of deep and long distance in railway, highway and water conservancy engineering construction, deep and long tunnel construction is facing challenges such as complex geological conditions, large burial depth, high groundwater pressure, and tunnel water inrush disaster has become a key risk source threatening construction safety.

[0003] However, in the prior art, there is a lack of systematic connection between the geological exploration results and the water inrush critical value calculation model, the acquisition of engineering geological parameters and hydrogeological parameters depends on scattered detection means, and a quantitative process integrating geophysical exploration and drilling data has not been formed, resulting in insufficient reliability of model input parameters. The water inrush critical value analysis model adopts a single theoretical framework, and cannot construct adaptive analysis models for different geological conditions such as complete hard rock section and fault fracture zone, resulting in limited applicability and accuracy of the calculation results in complex strata. The dynamic comparison mechanism of real-time monitoring data and critical value calculation results is weak, the risk level assessment lacks clear threshold standards, and the early warning response has lag and uncertainty. At the same time, the technology system does not integrate the feedback mechanism of historical construction cases, cannot optimize the risk assessment process based on the prevention and control effect data of similar geological conditions, and it is more difficult to realize the intelligent generation of prevention and control instructions and the continuous correction of model parameters, which seriously restricts the timeliness and effectiveness of construction safety guarantee. SUMMARY

[0004] The main purpose of the present application is to provide a deep and long tunnel water inrush critical value analysis method, which aims to realize accurate evaluation and prevention and control of deep and long tunnel water inrush risk.

[0005] To achieve the above purpose, the deep and long tunnel water inrush critical value analysis method provided by the present application comprises: Obtaining engineering geological parameters and hydrogeological parameters in front of the tunnel face; Based on the engineering geological parameters and hydrogeological parameters, a water inrush critical value analysis model is constructed to calculate the water inrush critical pressure value; Monitoring the real-time water pressure in front of the tunnel face to obtain a real-time water pressure monitoring value; Comparing the real-time water pressure monitoring value with the water inrush critical pressure value, and evaluating the water inrush risk level according to the comparison result; According to the water inrush risk level, generating and outputting construction early warning and risk prevention and control instructions.

[0006] In an embodiment, the step of obtaining engineering geological parameters and hydrogeological parameters in front of the tunnel face comprises: The TSP seismic wave method and the ground-penetrating radar method were used to detect the area in front of the tunnel face; Based on the detection results, advance drilling will be carried out in the predicted high-risk areas; Based on the core samples obtained from the advanced drilling and the water pressure data obtained by direct measurement, the engineering geological parameters and the hydrogeological parameters are determined in conjunction with the detection results.

[0007] In one embodiment, after the step of determining the engineering geological parameters and the hydrogeological parameters, the method for analyzing the critical value of water inrush in deep and long tunnels further includes: The detection results and the advanced drilling data are fused and processed with three-dimensional geological interpretation to generate a three-dimensional geological-hydrological model in front of the tunnel face; The surrounding rock grade, rock mass structure features, rock strength, in-situ stress, pore water pressure and permeability coefficient features in the three-dimensional geological-hydrological model are quantified into the engineering geological parameters and the hydrogeological parameters.

[0008] In one embodiment, the step of constructing the critical value analysis model for water inrush includes: Determine whether the geological conditions ahead of the tunnel face belong to a complete hard rock section or a fault fracture zone; If it is a complete hard rock segment, a water pressure fracturing model based on the thick-walled cylindrical theory is established; If it is a fault fracture zone, a sliding instability and water inrush model is established that considers the connectivity of the structural surfaces and the properties of the filling material.

[0009] In one embodiment, the water pressure fracturing model is used to calculate the critical pressure value Pc of the water inrush, and the calculation formula is as follows: Pc = KIc / (Y * sqrt(π * a)) + σt; Where KIc is the rock fracture toughness, Y is the geometric correction factor, a is the maximum primary fracture half-length, and σt is the minimum principal stress of the surrounding rock.

[0010] In one embodiment, the step of monitoring the real-time water pressure in front of the tunnel face includes: The real-time water pressure monitoring value is achieved by a piezometer embedded in the pre-drilled borehole or a high-pressure stop valve with a pressure gauge installed at the borehole opening. The real-time water pressure monitoring value is transmitted in real time via wired or wireless transmission.

[0011] In one embodiment, the step of comparing the real-time water pressure monitoring value with the critical pressure value for water inrush and assessing the risk level of water inrush based on the comparison result includes: Set a safety threshold coefficient η, where 0 < η < 1; If the real-time water pressure monitoring value is less than the product of η and the critical pressure value of the sudden water inrush, it is determined to be a low-risk level. If the real-time water pressure monitoring value is between the product of η and the critical pressure value of the water inrush and the critical pressure value of the water inrush, it is determined to be a medium risk level and an early warning is issued. If the real-time water pressure monitoring value reaches or exceeds the critical pressure value for sudden water inrush, it is determined to be a high-risk level and an early warning is issued.

[0012] In one embodiment, when assessed as a high-risk level, the generated construction early warning and risk control instructions include: stopping tunneling, performing full-section curtain grouting, densifying steel frame support and adding anchor bolts, activating high-power pumping equipment, and shortening the excavation advance.

[0013] In one embodiment, after the step of comparing the real-time water pressure monitoring value with the critical pressure value for water inrush, and before the step of generating and outputting construction early warning and risk prevention instructions based on the water inrush risk level, the method for analyzing the critical value of water inrush in deep and long tunnels further includes: The real-time water pressure monitoring value, the critical water inrush pressure value, the actual construction parameters, and the surrounding rock condition data of the current construction section are stored as historical cases. The current risk assessment results are matched and compared with historical cases with similar geological conditions in the historical case database. Based on the prevention and control effect data of the matched historical cases, the construction early warning and risk prevention and control instructions to be generated are pre-optimized.

[0014] In one embodiment, after generating and outputting construction early warning and risk prevention instructions, the method for analyzing the critical value of water inrush in deep and long tunnels further includes: Collect data on actual water inrush events that occurred after the completion of the construction section, the final stability state of the surrounding rock, and the execution effect data of the aforementioned risk prevention and control instructions; The collected actual data is compared with the original prediction results of the water inrush critical value analysis model; Based on the comparison results, the calculation parameters in the water inrush critical value analysis model are inverted and corrected to obtain optimized model parameters, and the water inrush critical value analysis model is updated.

[0015] The technical solution of this invention systematically acquires the engineering geological and hydrogeological parameters ahead of the tunnel face and constructs a targeted critical water inrush value analysis model based on these parameters, solving the problems of unsystematic acquisition of geological parameters and single calculation models in existing technologies. By quantifying the engineering geological and hydrogeological parameters and inputting them into the analysis model, the accuracy and reliability of the critical water inrush pressure value calculation are ensured, avoiding the subjectivity and uncertainty of traditional experience-based judgment methods. Furthermore, by monitoring the water pressure ahead of the tunnel face in real time and dynamically comparing the real-time water pressure monitoring value with the calculated critical water inrush pressure value, timely and accurate assessment of the water inrush risk level is achieved. Because a clear risk level determination standard is established, it no longer relies on vague experience-based judgments, and the risk state can be identified at the first moment of water pressure change, effectively solving the problems of untimely early warning response and vague risk assessment standards in existing technologies. In addition, by automatically generating and outputting targeted construction early warning and risk prevention instructions based on the assessed water inrush risk level, risk identification and emergency response are closely linked, simplifying the on-site decision-making process and reducing reliance on the professional judgment of construction management personnel. Since the prevention and control instructions are generated based on the results of quantitative risk level assessment, they can ensure the scientific nature and effectiveness of emergency measures, significantly improve the prevention and control capabilities of water inrush disasters during the construction of deep and long tunnels, ensure construction safety and project progress, effectively overcome many shortcomings of existing technologies, and provide reliable technical support for the safety of deep and long tunnel construction. 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 some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0017] Figure 1 This is a flowchart illustrating an embodiment of the critical value analysis method for water inrush in deep and long tunnels provided by the present invention.

[0018] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0019] 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 a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0020] It should be noted that if the embodiments of the present invention involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a specific posture. If the specific posture changes, the directional indicators will also change accordingly.

[0021] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the use of "and / or" or "and / or" throughout the text includes three parallel solutions. For example, "A and / or B" includes solution A, solution B, or a solution where both A and B are satisfied simultaneously. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0022] As tunnel engineering in railway, highway, and water conservancy projects continues to extend deeper and over longer distances, the construction of deep and long tunnels faces challenges such as complex geological conditions, great burial depth, and high groundwater pressure. Tunnel water inrush disasters have become a key risk source threatening construction safety. Water inrush critical value analysis technology, as a core component of risk assessment and prevention, has evolved from early rough estimations relying on engineering analogies and empirical formulas to quantitative analysis models incorporating fracture mechanics and seepage theory. In recent years, it has increasingly tended towards a comprehensive approach integrating geological exploration, real-time monitoring, and risk assessment. Current industry practice mainly adopts a model combining advanced geological prediction and theoretical calculation. Construction units use geophysical methods such as TSP seismic wave detection and ground-penetrating radar to detect geological anomalies ahead of the tunnel face, supplemented by advanced drilling to verify hydrogeological conditions. In the calculation of critical values ​​for water inrush, water pressure resistance formulas based on thick-walled cylindrical theory or water inrush criteria based on limit equilibrium theory are commonly used. Some projects have deployed real-time water pressure monitoring systems, which use piezometers or orifice pressure gauges buried in advanced boreholes to obtain data and compare it with theoretical calculation values ​​to determine the risk level, thereby triggering emergency response measures such as grouting reinforcement and strengthening of support.

[0023] However, the existing technical system has several shortcomings. There is a lack of systematic connection between geological survey results and the calculation model for water inrush critical values. The acquisition of engineering geological and hydrogeological parameters relies on fragmented detection methods, lacking a quantitative process that integrates geophysical and drilling data, resulting in insufficient reliability of model input parameters. Water inrush critical value analysis models often employ a single theoretical framework, failing to construct suitable analysis models for diverse geological conditions such as intact hard rock sections and fault fracture zones, thus limiting the applicability and accuracy of calculation results in complex strata. The dynamic comparison mechanism between real-time monitoring data and critical value calculation results is weak, risk level assessment lacks clear threshold standards, and early warning responses exhibit lag and uncertainty. Furthermore, the technical system lacks a feedback mechanism based on historical construction cases, making it impossible to optimize the risk assessment process based on prevention and control effect data under similar geological conditions. It also makes it difficult to achieve intelligent generation of prevention and control instructions and continuous correction of model parameters, severely restricting the timeliness and effectiveness of construction safety assurance.

[0024] To address this technical problem, this invention proposes a method for analyzing the critical value of water inrush in deep and long tunnels.

[0025] Please see Figure 1 In one embodiment of the present invention, the method for analyzing the critical value of water inrush in deep and long tunnels includes: S10, obtain the engineering geological parameters and hydrogeological parameters in front of the tunnel face; S20. Based on the engineering geological parameters and hydrogeological parameters, construct a critical value analysis model for water inrush to calculate the critical pressure value for water inrush. S30 monitors the real-time water pressure in front of the working face and obtains the real-time water pressure monitoring value; S40, compare the real-time water pressure monitoring value with the critical pressure value for water inrush, and assess the water inrush risk level based on the comparison result; S50 generates and outputs construction early warning and risk prevention instructions based on the water inrush risk level.

[0026] For ease of understanding, the following explains some key terms in this embodiment: The critical value analysis method for water inrush in deep and long tunnels refers to a systematic method that assesses geological and hydrological conditions, monitors water pressure in real time, and calculates using a specific model during the construction of deep and long tunnels to determine the possibility and risk level of water inrush in front of the tunnel face, and takes corresponding prevention and control measures accordingly.

[0027] Engineering geological parameters refer to quantitative indicators that describe the mechanical properties and geological structural characteristics of the surrounding rock of a tunnel, such as rock strength, surrounding rock grade, rock mass structural features, and in-situ stress. These parameters directly affect the stability and bearing capacity of the surrounding rock.

[0028] Hydrogeological parameters are quantitative indicators that describe the occurrence, movement, and pressure characteristics of groundwater, such as pore water pressure, permeability coefficient, and aquifer thickness. These parameters directly affect the effect of groundwater on the surrounding rock of tunnels and its potential for water inrush.

[0029] A critical water inrush pressure analysis model is a mathematical or physical model used to simulate the mechanical response of the surrounding rock in front of a tunnel face under groundwater pressure and to calculate the maximum water pressure that the surrounding rock can withstand (i.e., the critical water inrush pressure value). This model is the basis for assessing the risk of water inrush.

[0030] The critical pressure value for water inrush refers to the groundwater pressure threshold at which the surrounding rock ahead of the tunnel face is about to become unstable and fail under the influence of groundwater, leading to a water inrush. When the actual water pressure reaches or exceeds this value, the risk of water inrush increases significantly.

[0031] Real-time water pressure monitoring values ​​refer to the actual pressure data of groundwater ahead of the tunnel face, continuously or periodically acquired through on-site monitoring equipment. This data reflects the dynamic changes in current formation water pressure.

[0032] Water inrush risk level refers to the classification and assessment of the probability and potential hazard of a water inrush event occurring in front of the tunnel face, based on the comparison between real-time water pressure monitoring values ​​and the critical water inrush pressure value. It is typically classified as low risk, medium risk, and high risk.

[0033] Construction early warning and risk prevention instructions refer to specific guidance issued to the construction site based on the results of a water inrush risk level assessment, regarding adjustments to the construction plan, the adoption of emergency measures, or the strengthening of safety protection. These instructions aim to reduce the risk of water inrush and ensure construction safety.

[0034] The specific implementation process of the critical value analysis method for water inrush in deep and long tunnels in this application is as follows: First, the engineering geological and hydrogeological parameters ahead of the tunnel face must be obtained. These parameters can be acquired through various methods. For example, traditional geological survey methods such as on-site reconnaissance, geological sketching, and borehole sampling analysis can be used, combined with experience-based judgment, to make preliminary determinations. Alternatively, existing data such as regional geological data and hydrogeological reports can be reviewed and compiled. These methods provide basic information on geological and hydrogeological conditions, laying the foundation for subsequent analysis.

[0035] Furthermore, based on the acquired engineering geological and hydrogeological parameters, a critical value analysis model for water inrush is constructed to calculate the critical pressure value for water inrush. This model can be constructed using numerical simulation methods, such as the finite element method or discrete element method, by inputting geological parameters and boundary conditions to simulate the mechanical behavior of the surrounding rock, thereby determining its bearing capacity. Alternatively, empirical or semi-empirical formulas can be used, based on statistical data and theoretical derivations from similar projects, to establish simplified calculation models. These models can transform complex engineering geological and hydrogeological conditions into quantifiable critical pressure values ​​for water inrush.

[0036] During tunnel construction, it is necessary to monitor the real-time water pressure ahead of the tunnel face to obtain real-time water pressure readings. This monitoring can be achieved by setting up observation wells ahead of the tunnel face and manually taking readings using simple pressure gauges. Alternatively, pressure sensors with display functions can be installed in the boreholes, with on-site personnel periodically inspecting and recording the data. These monitoring methods provide the actual current groundwater pressure and are crucial data for dynamically assessing the risk of water inrush.

[0037] Subsequently, the real-time water pressure monitoring values ​​are compared with the critical pressure value for water inrush, and the water inrush risk level is assessed based on the comparison results. Specifically, if the real-time water pressure monitoring value is much lower than the critical pressure value for water inrush, it is determined to be low risk. If the real-time water pressure monitoring value is close to the critical pressure value for water inrush, it is determined to be medium risk. If the real-time water pressure monitoring value reaches or exceeds the critical pressure value for water inrush, it is determined to be high risk. This comparison mechanism can intuitively reflect the current degree of water inrush risk.

[0038] Finally, based on the assessed risk level of water inrush, construction early warning and risk control instructions are generated and output. When the risk level is low, the instruction "Normal construction, continuous monitoring" can be output. When the risk level is medium, the instruction "Strengthen monitoring, prepare emergency supplies" can be output. When the risk level is high, the instruction "Immediately stop work, activate the emergency plan" can be output. These instructions aim to guide construction personnel to take appropriate measures to address potential water inrush risks.

[0039] The proposed method for analyzing the critical value of water inrush in deep and long tunnels overcomes the limitations of unsystematic parameter acquisition and single-model approach in existing technologies by systematically acquiring engineering geological and hydrogeological parameters and constructing a critical value analysis model based on these parameters. Furthermore, this method achieves timely and accurate assessment of the water inrush risk level through real-time water pressure monitoring and dynamic comparison of critical values, solving the problem of untimely early warning responses in existing methods. Therefore, it can generate and output targeted construction early warnings and risk control instructions based on the risk level, effectively improving the safety assurance level during the construction of deep and long tunnels.

[0040] In an embodiment of the present invention, the step of obtaining the engineering geological parameters and hydrogeological parameters in front of the tunnel face includes: S11, the TSP seismic wave method and the ground-penetrating radar method are used to detect the area in front of the tunnel face; S12, based on the detection results, conduct advance drilling in the predicted high-risk areas; S13. Based on the core samples obtained from the advanced drilling and the water pressure data obtained by direct measurement, and in conjunction with the detection results, determine the engineering geological parameters and the hydrogeological parameters.

[0041] Specifically, the TSP (Tunnel Seismic Prediction) method is used to detect the area ahead of the tunnel face. This method utilizes the differences in the propagation speed and attenuation characteristics of seismic waves in different geological media. By exciting seismic waves inside the tunnel and receiving their reflected or transmitted waves, information such as waveform, travel time, and amplitude is analyzed to detect macroscopic geological anomalies such as geological structures, faults, fracture zones, lithological interfaces, and water-rich areas within a certain range ahead of the tunnel face. The TSP method is characterized by its large detection depth and strong penetration, making it suitable for detecting geological conditions at greater depths ahead of the tunnel. Simultaneously, the Ground Penetrating Radar (GPR) method is used to detect the area ahead of the tunnel face. This method transmits high-frequency electromagnetic waves and receives the signals reflected back from the underground medium. Based on the intensity, travel time, and waveform changes of the reflected waves, it detects shallow geological anomalies, cavities, fissures, water-bearing structures, and loose zones in the surrounding rock ahead of the tunnel face. The GPR method is characterized by its high resolution and good detection accuracy, making it suitable for detecting geological details at shallower depths ahead of the tunnel. Combining the TSP seismic wave method with the ground-penetrating radar method can achieve a detection effect that combines deep and shallow depths, as well as macroscopic and microscopic aspects, thus comprehensively improving the understanding of the geological conditions ahead of the tunnel face.

[0042] After completing the aforementioned exploration, based on the results of the TSP seismic wave method and ground-penetrating radar method, a comprehensive analysis and risk assessment are conducted on potential geological anomalies, water-rich areas, and fault fracture zones ahead of the tunnel face, thereby predicting potential high-risk areas. For these predicted high-risk areas, targeted advance drilling is implemented. Advance drilling is typically achieved by drilling horizontal or inclined boreholes at the tunnel face, with the aim of obtaining more direct and detailed geological and hydrological information. During the drilling process, core samples can be obtained, which can be used for laboratory rock mechanics tests, permeability tests, mineral composition analysis, etc., to obtain the physical and mechanical parameters of the rock. Simultaneously, by installing piezometers or using high-pressure stop valves with pressure gauges in the borehole, groundwater pressure data within the borehole can be directly measured, providing direct evidence for the determination of hydrogeological parameters.

[0043] Finally, based on the analysis results of core samples obtained from advanced drilling and the water pressure data directly measured, combined with the detection results of TSP seismic wave method and ground-penetrating radar method, all acquired information is comprehensively analyzed and interpreted to determine the engineering geological parameters and hydrogeological parameters ahead of the tunnel face. Engineering geological parameters may include surrounding rock grade, rock mass structural features (such as occurrence, spacing, aperture, and infill material), rock strength (such as uniaxial compressive strength and tensile strength), and in-situ stress state; hydrogeological parameters may include pore water pressure, permeability coefficient, and aquifer distribution. Through this multi-source data fusion approach, these key parameters can be quantified more accurately and comprehensively.

[0044] By employing the aforementioned technical solutions, combining the TSP seismic wave method and ground-penetrating radar to probe the area in front of the tunnel face, comprehensive and efficient geological structural information at both deep and shallow depths can be obtained. This effectively identifies potential high-risk areas such as water-rich zones and fault fracture zones, overcoming the limitations of single detection methods or traditional exploration techniques. Based on the preliminary detection results, targeted pre-drilling is carried out in predicted high-risk areas, avoiding blind drilling and improving exploration efficiency and economy. The core samples obtained from pre-drilling and the directly measured water pressure data provide direct and reliable evidence for the accurate determination of engineering geological and hydrogeological parameters. Finally, by comprehensively analyzing the detection results and drilling data, a more accurate and comprehensive understanding of the geological and hydrological conditions in front of the tunnel face can be achieved. This provides high-quality input parameters for subsequent water inrush critical value analysis models, significantly improving the accuracy and reliability of water inrush risk assessment and providing a solid guarantee for tunnel construction safety.

[0045] In an embodiment of the present invention, after the step of determining the engineering geological parameters and the hydrogeological parameters, the method for analyzing the critical value of water inrush in deep and long tunnels further includes: S201, The detection results and the advanced drilling data are fused and processed with three-dimensional geological interpretation to generate a three-dimensional geological-hydrological model in front of the tunnel face; S202, the surrounding rock grade, rock mass structural features, rock strength, geostress, pore water pressure and permeability coefficient features in the three-dimensional geological-hydrological model are quantified into the engineering geological parameters and the hydrogeological parameters.

[0046] Specifically, the fusion processing and three-dimensional geological interpretation of the aforementioned detection results and advanced drilling data refers to the comprehensive analysis and processing of detection results obtained through TSP seismic wave methods and ground-penetrating radar methods (such as stratigraphic interfaces, faults, and distribution of water-rich areas), core sample information obtained from advanced drilling (such as lithology, fracture development, and infill materials), and directly measured water pressure data. Fusion processing can employ various data fusion algorithms, such as geostatistical methods, neural network algorithms, or expert systems, to eliminate uncertainties and errors between different data sources and improve data reliability and consistency. Three-dimensional geological interpretation utilizes specialized geological modeling software to construct the three-dimensional spatial structure of the complex geological body ahead of the tunnel face by combining the fused two-dimensional detection profiles and one-dimensional borehole data with the regional geological background.

[0047] Based on this, a three-dimensional geological-hydrological model of the area in front of the tunnel face is generated. Using geological modeling software, the geological bodies (including strata, faults, fracture zones, water-rich structures, etc.) and their hydrological characteristics (such as groundwater level, water pressure distribution, and permeability areas) within a certain range in front of the tunnel face are presented as a three-dimensional digital model. This model not only includes the geometric shape and spatial location of the geological bodies, but also their internal attribute information, such as lithology, structural parameters, and hydrogeological parameters, providing a visualization and data foundation for subsequent parameter quantification.

[0048] Furthermore, the surrounding rock grade, rock mass structural features, rock strength, in-situ stress, pore water pressure, and permeability coefficient characteristics of the three-dimensional geological-hydrological model are quantified into the engineering geological parameters and the hydrogeological parameters. This refers to extracting and calculating specific numerical parameters from the generated three-dimensional geological-hydrological model for the critical value analysis model of water inrush. For example, the surrounding rock grade can be derived from the lithology and structural information in the model according to rock mass quality classification standards (e.g., RMR, Q system); rock mass structural features (e.g., occurrence, spacing, aperture, infill material) can be directly identified and measured from the three-dimensional model; rock strength (e.g., uniaxial compressive strength, tensile strength) can be interpolated by combining core test results with the lithology distribution in the model; in-situ stress can be simulated by combining regional in-situ stress field data with the geological structure in the model; pore water pressure and permeability coefficient can be extracted from the hydrogeological units in the model or obtained through hydrogeological simulation calculations. These quantified parameters are the inputs for constructing the critical value analysis model of water inrush, and their accuracy directly affects the prediction accuracy of the model.

[0049] By fusing and interpreting detection results and advanced drilling data from different sources using the aforementioned technical solution, the limitations of a single data source can be overcome, improving the completeness and accuracy of geological information. A three-dimensional geological-hydrological model of the tunnel face is generated, allowing for a direct and accurate presentation of complex geological structures and hydrological conditions, providing a reliable spatial reference for subsequent parameter extraction. Based on this, features such as surrounding rock grade, rock mass structural features, rock strength, geostress, pore water pressure, and permeability coefficient in the three-dimensional geological-hydrological model are quantified, ensuring the comprehensiveness, accuracy, and consistency of engineering geological parameters and hydrogeological parameters. This effectively solves the problems of fragmented parameter acquisition and inaccurate quantification in traditional methods, providing high-quality input data for the water inrush critical value analysis model, thereby significantly improving the accuracy and reliability of calculating the water inrush critical pressure value, and ultimately enhancing the accuracy of water inrush risk assessment.

[0050] In an embodiment of the present invention, the step of constructing the critical value analysis model for water inrush includes: S21, determine that the geological conditions in front of the tunnel face belong to a complete hard rock section or a fault fracture zone; S22, if it is a complete hard rock section, then establish a water pressure splitting model based on the thick-walled cylindrical theory; S23. If it is a fault fracture zone, then establish a sliding instability and water inrush model that considers the connectivity of the structural surface and the properties of the filling material.

[0051] The determination of whether the geological conditions ahead of the tunnel face constitute a complete hard rock segment or a fault fracture zone aims to select the analytical model that best matches the mechanical behavior and water inrush mechanism based on the actual geological conditions ahead of tunnel excavation. This determination can be based on previously acquired engineering geological and hydrogeological parameters. For example, through the results of TSP seismic wave detection and ground-penetrating radar detection, analysis of core samples obtained from advance drilling (such as rock mass quality index RQD, rock mass integrity coefficient), and geological interpretation results, the integrity of the rock mass, the presence of large faults, and the distribution range and characteristics of fracture zones can be identified. When the rock mass structure is intact, fissures are not developed, and rock strength is high, it can be determined as a complete hard rock segment; when there is a large amount of fractured rock, fault gouge, dense joints, and good connectivity, it is determined as a fault fracture zone.

[0052] If the section is determined to be intact hard rock, a water pressure-resistant splitting model based on the thick-walled cylinder theory is established. The thick-walled cylinder theory is a classic method in elasticity mechanics used to analyze the stress distribution of a thick-walled cylinder subjected to internal and external pressures. Applying it to tunnel engineering, it can simulate the stress state of the surrounding rock under water pressure. The water pressure-resistant splitting model focuses on analyzing the critical conditions for tensile or shear failure of the surrounding rock under water pressure. In intact hard rock sections, water inrush is often caused by high water pressure leading to the creation of new cracks within the rock mass or the expansion of existing micro-cracks, ultimately resulting in macroscopic splitting failure. This model calculates the critical water pressure that causes rock mass splitting by considering factors such as the tensile strength of the surrounding rock, the geostress state, and the tunnel geometry.

[0053] If the fault fracture zone is identified, a sliding instability and water inrush model is established, considering the connectivity of structural surfaces and the properties of the infill material. The rock mass structure of a fault fracture zone is complex, typically composed of numerous fractured rock blocks, fault gouge, or infill material. The water inrush mechanism mainly manifests as sliding instability of the fractured rock mass along structural surfaces (such as faults and joints), leading to the collapse of the surrounding rock and accompanied by a large influx of water. The connectivity of structural surfaces reflects the degree of interconnection within the fracture zone and is a key factor in the formation of water flow channels and the path of rock mass instability and failure. The properties of the infill material, such as its strength, permeability, and frictional characteristics, directly affect the shear strength of the structural surfaces and the transmission of water pressure. This model calculates the critical water pressure leading to sliding instability in the fracture zone by comprehensively considering the geometric characteristics of the structural surfaces, mechanical parameters (such as internal friction angle and cohesion), the properties of the infill material, the weakening effect of water pressure on the effective stress of the structural surfaces, and the geostress state.

[0054] Through the above technical solutions, when constructing the critical value analysis model for water inrush, intelligent judgment can be made based on the actual geological conditions ahead of the tunnel face, distinguishing between intact hard rock sections and fault fracture zones. For intact hard rock sections, a water pressure-resistant fracturing model based on the thick-walled cylinder theory is adopted, which can accurately simulate the fracturing failure mechanism of hard rock under water pressure, thereby accurately calculating its critical water inrush pressure. For fault fracture zones, a sliding instability water inrush model considering the connectivity of structural surfaces and the properties of infill materials is established. This model can more realistically reflect the water inrush mechanism of sliding instability of fractured rock mass along structural surfaces, effectively assessing its critical water inrush pressure. This strategy of adaptively selecting water inrush models based on geological conditions significantly improves the accuracy and reliability of calculating critical water inrush pressure, avoids the prediction bias that may be caused by a single model, and thus provides a more solid data foundation for subsequent water inrush risk assessment, making the determination of risk levels and the generation of construction early warning and risk prevention instructions more targeted and effective.

[0055] In an embodiment of the present invention, the water pressure fracturing model is used to calculate the critical pressure value Pc of the water inrush, and the calculation formula is as follows: Pc = KIc / (Y * sqrt(π * a)) + σt; Where KIc is the rock fracture toughness, Y is the geometric correction factor, a is the maximum primary fracture half-length, and σt is the minimum principal stress of the surrounding rock.

[0056] Specifically, the water-pressure-resistant fracturing model is based on the thick-walled cylinder theory and is applicable to intact hard rock sections. It aims to predict the critical conditions for rock mass fracturing failure under water pressure. In the formula, KIc represents rock fracture toughness, a physical quantity that measures the rock's ability to resist crack propagation, which can be obtained through rock mechanics tests. Y is the geometric correction factor, whose value is related to the geometry, size, and boundary conditions of the fracture, and is usually determined through numerical simulation or empirical formulas. a is the maximum primary fracture half-length, referring to half the maximum size of the inherent fracture in the rock mass, which can be obtained through geological exploration, geophysical surveys, etc. σt is the minimum principal stress of the surrounding rock, representing the minimum compressive stress of the surrounding rock in the direction perpendicular to the tunnel axis, which can be obtained through geostress measurement or inversion analysis. Accurately determining these parameters provides a solid physical basis for calculating the critical pressure of water inrush in intact hard rock sections.

[0057] The sliding instability water inrush model is primarily applied to areas with complex geological conditions and well-developed structural planes, such as fault fracture zones, to assess the risk of rock mass shear sliding instability along structural planes under water pressure. The model is based on the Mohr-Coulomb strength criterion, a widely used strength theory in geotechnical engineering that describes the stress state of rock or soil masses at shear failure. Its strength parameters include the internal friction angle and cohesion. Furthermore, the model specifically considers the weakening effect of fracture water pressure on the effective stress of structural planes. This means that water pressure in fractures reduces the normal stress on structural planes, thereby decreasing their shear strength and making the rock mass more susceptible to sliding instability. This weakening effect allows the model to more realistically reflect the mechanical response of fault fracture zones under water pressure, improving the accuracy of water inrush risk assessment.

[0058] Through the above technical solutions, this application provides a specific and physically meaningful calculation method for the critical value analysis of water inrush in deep and long tunnels. For intact hard rock sections, a water pressure fracturing model based on thick-walled cylindrical theory is adopted, and its calculation formula and the physical meaning of each parameter are clarified, providing a solid theoretical foundation and operability for calculating the critical water inrush pressure value. For fault fracture zones, the Mohr-Coulomb strength criterion is introduced as the calculation basis for the sliding instability water inrush model, and the weakening effect of fracture water pressure on the effective stress of the structural surface is particularly emphasized. This allows the model to more accurately simulate the impact of water pressure on rock mass stability under complex geological conditions. The clarification of these specific calculation methods and parameters significantly improves the accuracy and reliability of the critical water inrush pressure value calculation, thus providing a more accurate basis for subsequent water inrush risk level assessment. This not only enhances the scientific nature of risk assessment but also provides more reliable guidance for the formulation of construction early warning and risk prevention instructions, effectively reducing the risk of water inrush in the construction of deep and long tunnels and ensuring construction safety.

[0059] In an embodiment of the present invention, the step of monitoring the real-time water pressure in front of the tunnel face includes: S31 is achieved by a piezometer embedded in the pre-drilled borehole or a high-pressure stop valve with a pressure gauge installed at the borehole opening. The real-time water pressure monitoring value is transmitted in real time via wired or wireless transmission.

[0060] Specifically, a piezometer embedded in a pre-drilled borehole is a sensor used to measure pore water pressure. After pre-drilling ahead of the tunnel face, the piezometer can be embedded deep within the borehole, allowing it to directly contact the groundwater in the surrounding rock, thereby accurately measuring the pore water pressure at depth. Piezometers typically employ vibrating wire or resistance principles, outputting an electrical signal by sensing the deformation of a diaphragm caused by water pressure. During installation, it is crucial to ensure good hydraulic communication between the piezometer and the surrounding rock, and to effectively seal the borehole to prevent external water pressure interference and damage to the piezometer, ensuring the accuracy and long-term stability of the measurement data.

[0061] On the other hand, a high-pressure stop valve with a pressure gauge, installed at the borehole opening, is a device that integrates pressure measurement and borehole sealing functions. After pre-drilling is completed, this device can be installed and fixed at the borehole opening. The high-pressure stop valve effectively seals the borehole, preventing groundwater from gushing out, while its integrated pressure gauge directly displays or outputs the water pressure inside the borehole. This method is suitable for measuring the overall water pressure inside the borehole, especially when the water pressure is high or when rapid acquisition of borehole pressure data is required. The stop valve is designed to withstand high pressure and ensure reliable sealing, while the pressure gauge must have sufficient range and accuracy.

[0062] Furthermore, real-time transmission refers to the immediate transmission of real-time water pressure monitoring values ​​measured by piezometers or high-pressure stop valves with pressure gauges to a data processing center or monitoring platform via a data transmission system. This can be achieved through either wired or wireless methods. Wired transmission typically uses cables or fiber optics, offering advantages such as stable transmission and strong anti-interference capabilities, making it suitable for short-distance or fixed installation scenarios. Wireless transmission utilizes wireless communication technologies (such as Wi-Fi, Bluetooth, LoRa, cellular networks, etc.), offering advantages such as flexible wiring and convenient deployment, making it suitable for complex terrain or mobile monitoring scenarios. Regardless of the method used, the data transmission system must ensure the integrity, timeliness, and reliability of the data so that subsequent flood risk assessments can be based on the latest water pressure data.

[0063] To address the challenge of real-time water pressure monitoring ahead of the tunnel face in deep and long tunnels, this application provides two specific and reliable monitoring methods: a piezometer embedded in the pre-drilled borehole and a high-pressure stop valve with a pressure gauge installed at the borehole opening. The piezometer penetrates deep into the surrounding rock to directly obtain accurate pore water pressure data, reflecting the state of groundwater within the rock mass; while the high-pressure stop valve with a pressure gauge effectively monitors the water pressure at the borehole opening, suitable for quickly assessing the overall water pressure within the borehole. The combination of these two methods enables comprehensive and accurate acquisition of real-time water pressure monitoring values ​​ahead of the tunnel face, overcoming the potential lag or inaccuracy issues of traditional monitoring methods. Simultaneously, real-time transmission of monitoring data via wired or wireless methods ensures the timeliness and reliability of data transmission, allowing the critical water inrush value analysis model to always be calculated and evaluated based on the latest water pressure data. This significantly improves the accuracy of water inrush risk assessment and the timeliness of early warning, providing more precise and efficient safety assurance for tunnel construction. It enables the identification of potential water inrush risks earlier and more accurately, and timely implementation of corresponding risk prevention and control measures, effectively ensuring the safety of construction personnel and equipment.

[0064] In an embodiment of the present invention, the step of comparing the real-time water pressure monitoring value with the critical pressure value for water inrush and assessing the risk level of water inrush based on the comparison result includes: S41, Set the safety threshold coefficient η, where 0 < η < 1; S42, if the real-time water pressure monitoring value is less than the product of η and the critical pressure value of the sudden water inrush, it is determined to be a low-risk level; S43, if the real-time water pressure monitoring value is between the product of η and the critical pressure value of the water inrush and the critical pressure value of the water inrush, it is determined to be a medium risk level and an early warning is issued; S44. If the real-time water pressure monitoring value reaches or exceeds the critical pressure value for water inrush, it is determined to be a high-risk level and an early warning is issued.

[0065] The safety threshold coefficient η is a preset decimal between 0 and 1, used to classify different risk level ranges based on the critical pressure value Pc for water inrush. The introduction of this coefficient transforms risk assessment from a simple "yes / no" judgment into a multi-level risk early warning mechanism based on the relative relationship between real-time water pressure monitoring values ​​and the critical pressure value Pc. For example, η can be set based on factors such as engineering experience, geological complexity, and construction safety requirements, with a common value range between 0.6 and 0.9. By adjusting η, the sensitivity and lead time of the early warning can be flexibly controlled.

[0066] When the real-time water pressure monitoring value is less than the product of η and the critical pressure value for water inrush, it indicates that the current water pressure in front of the tunnel face poses a relatively small threat to the surrounding rock, and the risk of water inrush is within a controllable and safe range. At this time, the system determines it to be a low-risk level, and usually no additional risk control measures are required. Construction can proceed normally, thus avoiding unnecessary work stoppages or waste of resources.

[0067] When the real-time water pressure monitoring value falls between the product of η and the critical pressure value for water inrush and the critical pressure value for water inrush, it indicates that the risk of water inrush is increasing and requires attention. At this time, the system determines it to be at a medium risk level and automatically issues an early warning. This warning can take various forms, such as audible and visual alarms, SMS notifications, and system interface prompts, to remind construction and management personnel to pay attention to changes in water pressure and prepare to activate corresponding risk prevention and control plans, such as increasing monitoring frequency, inspecting drainage equipment, and preparing grouting materials.

[0068] When the real-time water pressure monitoring value reaches or exceeds the critical pressure value for water inrush, it indicates that the surrounding rock in front of the tunnel face may already be in an unstable or imminent state, with an extremely high risk of water inrush and the possibility of water surge at any time. At this point, the system determines it to be at a high risk level and immediately issues the highest level of warning. This warning is usually accompanied by mandatory risk control instructions, such as requiring the immediate cessation of tunneling, evacuation of personnel, activation of high-power drainage equipment, and implementation of emergency grouting, in order to avoid or mitigate the occurrence of water inrush accidents to the greatest extent possible.

[0069] Through the above technical solution, this application refines the single critical pressure value Pc for water inrush into multiple risk level ranges. When the real-time water pressure monitoring value is far below the critical value, the system determines it as low risk, ensuring normal construction and avoiding unnecessary interference. As the water pressure gradually increases, when it falls between the product of η and the critical pressure value Pc and the critical pressure value Pc, the system can promptly identify and issue a medium-risk warning, providing valuable warning time for the construction party, enabling them to take preventative measures in advance, such as strengthening monitoring and preparing emergency supplies, thereby controlling potential risks at their inception. Once the real-time water pressure monitoring value reaches or exceeds the critical pressure value Pc, the system immediately determines it as high risk and issues an emergency warning, triggering the highest level of risk control instructions, ensuring that measures can be taken quickly and decisively before or in the early stages of a water inrush event, maximizing personnel safety and project stability. This tiered early warning mechanism makes risk assessment more refined and intelligent, effectively improving the scientific nature and initiative of water inrush risk management during the construction of deep and long tunnels, avoiding the lag or overreaction that may be caused by traditional binary judgment, and significantly improving construction safety and efficiency.

[0070] In an embodiment of the present invention, when the risk level is assessed as high, the generated construction early warning and risk control instructions include: stopping tunneling, performing full-section curtain grouting, densifying steel frame support and adding anchor bolts, activating high-power pumping equipment, and shortening the excavation advance.

[0071] Specifically, when the risk assessment for water inrush in deep and long tunnels is high-risk, immediately halting tunnel excavation is the primary and most direct risk control measure. This aims to prevent further disturbance of the surrounding rock, prevent stress concentration or damage to the rock structure caused by excavation activities, which could trigger or accelerate water inrush events, and buy valuable time and space for subsequent risk prevention and control measures. Simultaneously, full-face curtain grouting is an engineering measure that injects grout into the surrounding rock to fill fissures and pores, reduce permeability, and improve overall stability. In high-risk areas, full-face curtain grouting can form an effective water-stopping curtain, blocking or weakening the seepage channels of groundwater into the tunnel, thereby reducing water pressure and preventing water inrush. Grouting materials can include cement grout, chemical grout, or composite grout, selected based on geological conditions and hydrological characteristics. Strict control of grouting pressure and volume is necessary to ensure sufficient diffusion and solidification of the grout. Furthermore, the use of reinforced steel frame supports and additional anchor bolts significantly enhances the overall load-bearing capacity and stability of the tunnel, preventing deformation or collapse of the surrounding rock. It also anchors the steel frame support to the deep surrounding rock, further improving the integrity and deformation resistance of the support structure. This effectively resists the destructive effects of water pressure and ground stress on the surrounding rock, especially in areas at the tunnel bottom or sidewalls susceptible to water pressure. To address potential water inrushes, high-powered drainage equipment can efficiently remove accumulated water from the tunnel, lowering the water level and reducing the threat of water pressure to the support structure and construction personnel, thus creating conditions for subsequent emergency rescue and repair work. This equipment typically needs to be pre-deployed inside or near the tunnel, ensuring its power supply and unobstructed drainage channels. Finally, shortening the excavation advance refers to reducing the length of each blast or mechanical excavation during the tunneling process. In areas with a high risk of water inrush, this can reduce the area of ​​surrounding rock exposed at one time, reduce the risk of surrounding rock instability, and facilitate faster implementation of initial support and water-stopping measures. This keeps the risk within a smaller range, provides a safer working environment for construction workers, and facilitates the timely detection and handling of potential water inrush hazards.

[0072] The above technical solutions provide a comprehensive, systematic, and targeted risk prevention and control framework when deep and long tunnels face a high risk of water inrush. Specifically, immediately halting excavation prevents further disturbance of the surrounding rock, buying time for subsequent measures; full-face curtain grouting effectively blocks groundwater channels and reduces water pressure; densifying steel frame support and adding anchor bolts significantly enhances the stability of the tunnel structure, resisting water pressure and ground stress; utilizing high-powered drainage equipment ensures rapid drainage in the event of a water inrush, mitigating the damage; and shortening the excavation advance limits the risk to a smaller area, facilitating timely handling. These measures work together to form a multi-layered, three-dimensional safety defense line, effectively reducing the probability of water inrush events and minimizing losses in the event of one, ensuring the safety of construction personnel and the smooth progress of the project. Compared to simply issuing warnings, this solution provides specific and actionable response strategies, greatly enhancing risk management and emergency response capabilities during the construction of deep and long tunnels.

[0073] In an embodiment of the present invention, after the step of comparing the real-time water pressure monitoring value with the critical pressure value for water inrush, and before the step of generating and outputting construction early warning and risk prevention instructions based on the water inrush risk level, the method for analyzing the critical value of water inrush in deep and long tunnels further includes: F10 stores the real-time water pressure monitoring value, the critical water inrush pressure value, the actual construction parameters, and the surrounding rock condition data of the current construction section as historical cases. F20 matches and compares the current risk assessment results with historical cases with similar geological conditions in the historical case database. Based on the prevention and control effect data of the matched historical cases, the construction early warning and risk prevention and control instructions to be generated are pre-optimized.

[0074] Specifically, during tunnel excavation, the system continuously records and collects various key data for the current construction section. These include real-time water pressure monitoring values, which are data on the water pressure ahead of the tunnel face obtained through devices such as piezometers embedded in the pre-drilled boreholes or high-pressure stop valves with pressure gauges installed at the borehole openings; critical water inrush pressure values, which are thresholds calculated based on a constructed critical water inrush value analysis model; actual construction parameters, including but not limited to the current excavation method, support type, excavation progress, and grouting parameters; and surrounding rock condition data, which covers information such as surrounding rock grade, rock mass structural features, rock strength, ground stress, pore water pressure, and permeability coefficient. This data is structured and stored in a historical case database, forming a complete historical case record for subsequent retrieval and analysis.

[0075] Once the system completes the risk assessment of water inrush in the current construction section and determines the risk level, it uses an intelligent matching algorithm to search the historical case database for historical cases that are highly similar to the current geological conditions (such as surrounding rock type, hydrogeological conditions, and geostress environment). The matched historical cases not only include the geological and hydrological parameters and risk assessment results at the time, but also record in detail the risk prevention and control measures taken and their final effectiveness (e.g., whether water inrush was successfully avoided, the cost of the measures, implementation period, and impact on construction progress). Through analysis of this prevention and control effectiveness data, the system can intelligently adjust and optimize the initially generated construction warnings and risk prevention and control instructions. For example, it can adjust the grout mix ratio, grout hole spacing, support steel frame spacing, anchor bolt length and density, or adjust the power and start-up timing of the pumping and drainage equipment to ensure the scientific, economical, and effective nature of the instructions.

[0076] By storing real-time water pressure monitoring values, critical water inrush pressure values, actual construction parameters, and surrounding rock conditions of the current construction section as historical cases, and further matching and comparing the current risk assessment results with historical cases with similar geological conditions in the historical case database, past construction experience and risk prevention practices can be fully utilized. Based on the prevention and control effect data of the matched historical cases, the upcoming construction early warning and risk prevention instructions are pre-optimized, making the generated instructions more targeted, effective, and economical. This not only avoids the risks of blindly taking measures or taking insufficient measures, but also significantly improves the quality and efficiency of risk prevention and control decisions, ensures the safety and stability of tunnel construction, and effectively reduces the probability of water inrush accidents and the potential losses they may cause.

[0077] In an embodiment of the present invention, after the step of generating and outputting construction early warning and risk prevention instructions, the method for analyzing the critical value of water inrush in deep and long tunnels further includes: P10, collect data on actual water inrush events that occurred after the completion of the construction section, the final stability state of the surrounding rock, and the execution effect data of the aforementioned risk prevention and control instructions; P20, compare the collected actual data with the original prediction results of the water inrush critical value analysis model; P30. Based on the comparison results, the calculation parameters in the water inrush critical value analysis model are inverted and corrected to obtain optimized model parameters, and the water inrush critical value analysis model is updated.

[0078] Specifically, after the completion of a section of tunnel construction, detailed data collection on the actual conditions of that section is required. "Collecting data on actual water inrush events after the completion of the construction section" refers to recording and quantifying any water inrush phenomena that actually occur within that construction section, including the time, location, volume (e.g., hourly volume), water pressure, water quality characteristics, and duration of the inrush. This data can be obtained through on-site observation, flow meters, pressure sensors, and other equipment. "Final stable state of the surrounding rock" refers to assessing the long-term deformation, crack development, stress on the support structure, and overall stability of the surrounding rock after excavation of the construction section. This can be obtained through geological mapping, deformation monitoring (such as convergence meters and multi-point displacement gauges), and stress monitoring of anchor bolts or shotcrete. "Data on the effectiveness of risk control directives" refers to the evaluation of the actual implementation and effectiveness of construction warnings and risk control directives (such as grouting, drainage, and reinforced support) issued based on risk assessment results. This includes the scope of implementation, grouting volume, drainage volume, installation quality of the support structure, and the actual impact of these measures on surrounding rock stability and water pressure control. The collection of this data is fundamental to ensuring that the model can learn from practical experience.

[0079] Subsequently, the collected actual data is compared with the prediction results generated by the water inrush critical value analysis model during risk assessment in the construction section. For example, the model may predict a high risk of water inrush and a specific critical pressure value in a certain area, while the actual data shows that no water inrush occurred in the area or the water inrush volume was much lower than predicted, or vice versa. This comparison aims to identify the deviation between the model prediction and the actual situation, thereby identifying potential shortcomings of the model.

[0080] Based on these comparative results, the calculation parameters in the water inrush critical value analysis model are inverted and corrected. Inversion is a method of inferring unknown parameters from known results. For example, optimization algorithms, machine learning methods, or statistical analysis techniques can be used to adjust the calculation parameters within the model, such as rock mass strength parameters, permeability coefficient, structural surface connectivity, and in-situ stress, based on actual water inrush event data, the final stability state of the surrounding rock, and the execution effect data of risk prevention and control instructions. The correction process aims to reduce the error between the model's predicted values ​​and actual observations, enabling the model to more accurately reflect actual geological and hydrological conditions. Through this process, a set of optimized model parameters can be obtained, which can better explain the actual situation. Finally, these optimized model parameters are used to update the water inrush critical value analysis model, giving it higher prediction accuracy and reliability, and providing a more accurate basis for risk assessment of subsequent construction sections.

[0081] Through the above technical solution, this application introduces a mechanism for collecting actual data after the completion of the construction section and comparing it with the model's prediction results. This mechanism enables the inversion and correction of the calculation parameters in the water inrush critical value analysis model. This allows the model to learn from actual construction experience and continuously optimize its predictive capabilities, thereby overcoming potential biases in the initial model parameters or insufficient adaptability to complex geological conditions. The updated model parameters more accurately reflect actual geological and hydrological conditions, significantly improving the accuracy of subsequent water inrush risk assessments and the effectiveness of construction early warning and risk control instructions. This effectively reduces the risk of water inrush during tunnel construction, ensuring construction safety and project progress.

[0082] The following example will provide a more detailed explanation of the above technical solution: In section A of a long and deep tunnel project B, which faces challenges of complex geological conditions and high groundwater pressure, the construction team decided to adopt an advanced critical value analysis method for water inrush in order to effectively prevent water inrush disasters.

[0083] First, ahead of the tunnel face, the construction team acquired engineering geological and hydrogeological parameters through comprehensive geological exploration methods. Specifically, the TSP seismic wave method and ground-penetrating radar method were used to conduct advance exploration ahead of the tunnel face to identify potential geological anomalies and water-rich areas. Based on the preliminary exploration results, advance drilling was carried out in the predicted high-risk areas. Core samples were obtained through advance drilling, and water pressure data within the boreholes were directly measured. These core samples were used for laboratory testing to obtain the mechanical parameters of the rock, such as compressive strength, tensile strength, and fracture toughness. Simultaneously, the exploration results and advance drilling data were combined and processed with three-dimensional geological interpretation to generate a three-dimensional geological-hydrological model ahead of the tunnel face. In this model, characteristics such as surrounding rock grade, rock mass structural features, rock strength, in-situ stress, pore water pressure, and permeability coefficient were quantified into specific engineering geological and hydrogeological parameters. This systematic parameter acquisition and quantification method overcomes the problems of unsystematic and inaccurate parameter acquisition in existing technologies, providing reliable input for subsequent critical value calculations.

[0084] Next, based on these precise engineering geological and hydrogeological parameters, a critical water inrush value analysis model is constructed to calculate the critical water inrush pressure value. When constructing the model, the geological conditions ahead of the tunnel face are first determined. For example, if it is determined to be a complete hard rock section, a water pressure fracturing resistance model based on the thick-walled cylindrical theory is established. This model is used to calculate the critical water inrush pressure value Pc, and its calculation formula is Pc = KIc / (Y * sqrt(π * a)) + σt, where KIc is the rock fracture toughness, Y is the geometric correction factor, a is the maximum primary fracture half-length, and σt is the minimum principal stress of the surrounding rock. If it is determined to be a fault fracture zone, a sliding instability water inrush model considering the connectivity of structural surfaces and the properties of the infill material is established. Its calculation is based on the Mohr-Coulomb strength criterion and considers the weakening effect of fracture water pressure on the effective stress of the structural surfaces. This approach of establishing differentiated analysis models for different geological conditions avoids the limitations of single theoretical models in existing technologies and improves the applicability and accuracy of the calculation results.

[0085] During construction, the real-time water pressure in front of the tunnel face is continuously monitored. Water pressure readings are obtained in real time through piezometers embedded in the pre-drilled borehole, or through high-pressure stop valves equipped with pressure gauges installed at the borehole opening. These real-time water pressure readings are transmitted to the monitoring center via wired or wireless transmission.

[0086] Subsequently, the real-time water pressure monitoring value is compared with the critical pressure value for water inrush, and the risk level of water inrush is assessed based on the comparison result. In this process, a safety threshold coefficient η is set, for example, 0.7, where 0 < η < 1. If the real-time water pressure monitoring value is less than the product of η and the critical pressure value for water inrush (i.e., less than 0.7 times the critical pressure value), it is determined to be a low-risk level. If the real-time water pressure monitoring value is between the product of η and the critical pressure value for water inrush and the critical pressure value for water inrush (i.e., between 0.7 and 1 times the critical pressure value), it is determined to be a medium-risk level and an early warning is issued. If the real-time water pressure monitoring value reaches or exceeds the critical pressure value for water inrush, it is determined to be a high-risk level and an early warning is issued. This clear risk level assessment standard compensates for the shortcomings of existing technologies, such as vague risk assessment standards and untimely and inaccurate early warning responses.

[0087] Based on the assessed risk level of water inrush, the system automatically generates and outputs construction early warnings and risk control instructions. For example, when the assessment is high-risk, the generated instructions may include: immediately stopping tunneling operations, performing full-face curtain grouting to seal the water-bearing structure, densifying steel frame support and adding anchor bolts to enhance surrounding rock stability, activating high-power pumping equipment to lower the groundwater level, and shortening the excavation advance to reduce the exposed area. Before generating instructions, the system also stores the real-time water pressure monitoring values, critical water inrush pressure values, actual construction parameters, and surrounding rock conditions of the current construction section as historical cases. Simultaneously, it matches and compares the current risk assessment results with historical cases with similar geological conditions in the historical case database. Based on the control effectiveness data of the matched historical cases, the system pre-optimizes the upcoming construction early warnings and risk control instructions. This pre-optimization mechanism based on historical experience makes the control instructions more targeted and effective, improving the overall efficiency of construction safety assurance.

[0088] After the construction section is completed, the system also collects data on actual water inrush events, the final stability state of the surrounding rock, and the execution effect data of risk prevention and control instructions. The collected actual data is compared with the original prediction results of the water inrush critical value analysis model. Based on the comparison results, the calculation parameters in the water inrush critical value analysis model are inverted and corrected to obtain optimized model parameters, and the water inrush critical value analysis model is updated. This continuous model optimization mechanism solves the problem of insufficient experience feedback and model optimization in existing technologies, realizing the intelligent generation and continuous improvement of water inrush risk prevention and control measures, thereby continuously improving the accuracy of prediction and the effectiveness of prevention and control.

[0089] The above description is merely an exemplary embodiment of the present invention and does not limit the scope of protection of the present invention. Any equivalent structural transformations made based on the technical concept of the present invention and the contents of the specification and drawings of the present invention, or direct / indirect applications in other related technical fields, are included within the scope of protection of the present invention.

Claims

1. A method for analyzing the critical value of water inrush in deep and long tunnels, characterized in that, The critical value analysis method for water inrush in deep and long tunnels includes: Obtain engineering geological and hydrogeological parameters in front of the tunnel face; Based on the aforementioned engineering geological parameters and hydrogeological parameters, a critical value analysis model for water inrush is constructed to calculate the critical pressure value for water inrush. Monitor the real-time water pressure in front of the working face and obtain the real-time water pressure monitoring value; The real-time water pressure monitoring value is compared with the critical pressure value for water inrush, and the water inrush risk level is assessed based on the comparison result. Based on the water inrush risk level, construction early warning and risk prevention instructions are generated and output.

2. The method for analyzing the critical value of water inrush in deep and long tunnels as described in claim 1, characterized in that, The steps for obtaining the engineering geological parameters and hydrogeological parameters in front of the tunnel face include: The TSP seismic wave method and the ground-penetrating radar method were used to detect the area in front of the tunnel face; Based on the detection results, advance drilling will be carried out in the predicted high-risk areas; Based on the core samples obtained from the advanced drilling and the water pressure data obtained by direct measurement, the engineering geological parameters and the hydrogeological parameters are determined in conjunction with the detection results.

3. The method for analyzing the critical value of water inrush in deep and long tunnels as described in claim 2, characterized in that, Following the step of determining the engineering geological parameters and the hydrogeological parameters, the method for analyzing the critical value of water inrush in deep and long tunnels further includes: The detection results and the advanced drilling data are fused and processed with three-dimensional geological interpretation to generate a three-dimensional geological-hydrological model in front of the tunnel face; The surrounding rock grade, rock mass structure features, rock strength, in-situ stress, pore water pressure and permeability coefficient features in the three-dimensional geological-hydrological model are quantified into the engineering geological parameters and the hydrogeological parameters.

4. The method for analyzing the critical value of water inrush in deep and long tunnels as described in claim 1, characterized in that, The steps for constructing the critical value analysis model for water inrush include: Determine whether the geological conditions ahead of the tunnel face belong to a complete hard rock section or a fault fracture zone; If it is a complete hard rock segment, a water pressure fracturing model based on the thick-walled cylindrical theory is established; If it is a fault fracture zone, a sliding instability and water inrush model is established that considers the connectivity of the structural surfaces and the properties of the filling material.

5. The method for analyzing the critical value of water inrush in deep and long tunnels as described in claim 4, characterized in that, The water pressure fracturing model is used to calculate the critical pressure value Pc of the water inrush, and its calculation formula is as follows: Pc = KIc / (Y * sqrt(π * a)) + σt; Where KIc is the rock fracture toughness, Y is the geometric correction factor, a is the maximum primary fracture half-length, and σt is the minimum principal stress of the surrounding rock.

6. The method for analyzing the critical value of water inrush in deep and long tunnels as described in claim 1, characterized in that, The steps for monitoring the real-time water pressure in front of the tunnel face include: The real-time water pressure monitoring value is achieved by a piezometer embedded in the pre-drilled borehole or a high-pressure stop valve with a pressure gauge installed at the borehole opening. The real-time water pressure monitoring value is transmitted in real time via wired or wireless transmission.

7. The method for analyzing the critical value of water inrush in deep and long tunnels as described in claim 1, characterized in that, The step of comparing the real-time water pressure monitoring value with the critical pressure value for water inrush and assessing the risk level of water inrush based on the comparison result includes: Set a safety threshold coefficient η, where 0 < η < 1; If the real-time water pressure monitoring value is less than the product of η and the critical pressure value of the sudden water inrush, it is determined to be a low-risk level. If the real-time water pressure monitoring value is between the product of η and the critical pressure value of the water inrush and the critical pressure value of the water inrush, it is determined to be a medium risk level and an early warning is issued. If the real-time water pressure monitoring value reaches or exceeds the critical pressure value for sudden water inrush, it is determined to be a high-risk level and an early warning is issued.

8. The method for analyzing the critical value of water inrush in deep and long tunnels as described in claim 7, characterized in that, When assessed as a high-risk level, the generated construction early warning and risk control instructions include: stopping tunneling, performing full-section curtain grouting, densifying steel frame support and adding anchor bolts, activating high-power pumping equipment, and shortening the excavation advance.

9. The method for analyzing the critical value of water inrush in deep and long tunnels as described in claim 1, characterized in that, After the step of comparing the real-time water pressure monitoring value with the critical pressure value for water inrush, and before the step of generating and outputting construction early warning and risk prevention instructions based on the water inrush risk level, the method for analyzing the critical value of water inrush in deep and long tunnels further includes: The real-time water pressure monitoring value, the critical water inrush pressure value, the actual construction parameters, and the surrounding rock condition data of the current construction section are stored as historical cases. The current risk assessment results are matched and compared with historical cases with similar geological conditions in the historical case database. Based on the prevention and control effect data of the matched historical cases, the construction early warning and risk prevention and control instructions to be generated are pre-optimized.

10. The method for analyzing the critical value of water inrush in deep and long tunnels as described in claim 9, characterized in that, After generating and outputting construction early warning and risk prevention instructions, the method for analyzing the critical value of water inrush in deep and long tunnels further includes: Collect data on actual water inrush events that occurred after the completion of the construction section, the final stability state of the surrounding rock, and the execution effect data of the aforementioned risk prevention and control instructions; The collected actual data is compared with the original prediction results of the water inrush critical value analysis model; Based on the comparison results, the calculation parameters in the water inrush critical value analysis model are inverted and corrected to obtain optimized model parameters, and the water inrush critical value analysis model is updated.

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