Fast analysis and treatment method and system for cutting and breaking mode of boulder by shield cutter

Abstract

This invention belongs to the field of shield tunnel construction technology and discloses a rapid analysis and treatment method and system for the fracture mode of isolated boulders cut by shield tunneling cutterheads. The invention obtains parameters of the isolated boulder, cutterhead, and tunneling; selects the Hertz-Mindlin with bonding V2 model and the JKR model as the contact models between the isolated boulder and the soil, respectively; calibrates microscopic parameters and establishes a model of the isolated boulder and soil using single-size particles; constructs a coupled model of the isolated boulder-soil-cutterhead for simulation; extracts the cutterhead stress, crack penetration rate, force chain evolution, and isolated boulder displacement to determine the fracture mode as overall fracture, partial fracture, or primarily movement, and then performs treatment. This invention is applicable to construction in central urban areas where ground treatment is difficult, providing a safe, feasible, and efficient solution to the industry problem of dealing with high-strength, easily rolling isolated boulders, greatly reducing the risks of shield tunneling stoppage, abnormal cutterhead damage, and excessive surface settlement.

Description

Technical Field

[0001] This invention belongs to the field of shield tunnel construction technology, and in particular relates to a rapid analysis and treatment method and system for the fracture mode of isolated boulders cut by shield roller cutters. Background Technology

[0002] Shield tunneling has been widely applied in urban tunnel and underground space engineering construction. When a shield tunnel passes through strata rich in boulders, whether the boulders can be effectively broken by the cutterhead's roller cutters directly affects the tunneling efficiency and construction safety. Currently, there are several main methods for dealing with boulders encountered during shield tunneling: The first method is to determine the location, size, and distribution of the boulders using geophysical exploration and drilling, and then select methods such as surface drilling and blasting, shaft treatment, or manual obstacle removal based on the size and depth of the boulders; the second method is to attempt to directly break the boulders using the roller cutters by adjusting tunneling parameters such as shield thrust, cutterhead rotation speed, and penetration depth, based on shield tunneling experience; the third method is to utilize the theory of roller cutter rock breaking in intact hard rock or composite strata, judging the hardness and rock breaking state of the boulders by the changes in roller cutter force, cutterhead torque, or tunneling parameters.

[0003] While the aforementioned existing technologies can address the challenges of constructing tunnels in boulder formations to some extent, they still have significant shortcomings. For the first type of method, methods such as surface drilling and blasting, constructing inspection wells, or manual clearing are heavily limited by surface conditions, especially in urban centers, densely built-up areas, areas with complex underground pipelines, or busy traffic areas. These methods are often difficult to implement, and even if feasible, they increase construction costs, extend the construction period, and introduce ground disturbance and environmental safety risks. For the second type of method, it relies heavily on construction experience to adjust shield tunneling parameters, lacking prior assessment of the boulder's fracturing mode. This can easily lead to insufficient parameters resulting in ineffective boulder fracturing, or excessive parameters causing problems such as cutterhead wear, cutterhead vibration, abnormal main bearing load, and increased ground disturbance. For the third type of method, the theory of intact hard rock fracturing typically assumes continuous constraints on the rock mass. However, boulders buried in soil have weaker constraints and a degree of mobility. When subjected to the action of the cutterhead, they may not undergo continuous fracturing but rather slippage, rolling, or deflection. Therefore, directly applying the hard rock fracturing theory cannot accurately reflect the actual fracturing behavior of boulder formations. Summary of the Invention

[0004] To address the challenges of establishing a coupled model of boulder, soil, and cutterhead under the action of a cutterhead, and transforming the boulder fracturing problem into software for accurate and rapid analysis of three fracturing modes, this invention discloses a rapid analysis and treatment method and system for boulder fracturing modes using shield tunneling cutterheads. The method addresses how to accurately determine the three fracturing modes of a boulder by combining cutterhead stress, boulder crack penetration rate, boulder force chain changes, and boulder displacement criteria. It also addresses how to transform the local fracturing mode and the movement-based fracturing mode of a boulder into a comprehensive fracturing mode, overcoming the shortcomings of existing technologies such as lack of quantitative criteria for boulder fracturing, direct application of hard rock tunneling parameters leading to blockage or ground disturbance, failure to reveal the three typical fracturing modes and their transformation mechanisms, and poor applicability and high risk of auxiliary treatment methods in urban centers. The technical solution is as follows: This invention is implemented as follows: a rapid analysis and treatment method for the fracture mode of isolated boulders cut by shield tunneling cutterheads, comprising the following steps: S1. Obtain the boulder parameters, shield cutter head structure parameters, and tunneling parameters of the target project, and substitute the obtained parameters into the discrete element method software EDEM; S2. Select the discrete element contact model between the boulder and the soil. The Hertz-Mindlin with bonding V2 model is used for the brittle fracture contact model of the boulder, and the JKR model is used for the discrete element contact model of the soil. S3. Based on the selected contact model, the microscopic parameters of the boulder and the soil are calibrated, and the boulder model and the soil model are established using single-size particles respectively. S4. Based on the calibrated parameters and the established model, construct an overall model of the isolated rock-soil-roll cutter coupling shield tunneling isolated rock strata to form a calculation sample for the roll cutter to cut the isolated rock strata; S5. Run simulation calculations and use EDEM post-processing tools to extract the roller cutter stress data, boulder crack penetration rate, boulder force chain evolution characteristic map, and boulder centroid relative movement rate. Based on the extracted data, determine whether the boulder belongs to the overall fracture mode, local fracture mode, or non-obvious fracture mode dominated by movement, and perform corresponding treatment operations based on the judgment results. When it is determined to be a local fracture mode, generate a treatment plan to increase the roller cutter penetration to transform the local fracture mode into an overall fracture mode. When it is determined to be a non-obvious fracture mode dominated by movement, generate a treatment plan to strengthen the soil constraint around the boulder to transform the non-obvious fracture mode dominated by movement into an overall fracture mode.

[0005] In step S1, the boulder parameter information includes: the boulder's size and appearance obtained through geophysical exploration and drilling; The shield cutterhead structural parameters include the cutterhead dimensions; The tunneling parameters include the penetration depth and cutterhead rotation speed set by the tunnel boring machine.

[0006] In step S3, the micro-parameters of the boulder and the soil are calibrated according to the selected contact model, including: the micro-parameters of the boulder are calibrated by uniaxial compression test and Brazilian splitting test, and the micro-parameters of the soil are calibrated by direct shear test.

[0007] In step S4, a calculation sample for cutting isolated rock formations with a cutter is formed, including: constructing a corresponding calculation sample for cutting isolated rock formations with a cutter based on the shield cutter structure parameters and tunneling parameters obtained from different engineering sites; the cutter model is located at the upper center of the isolated rock mass, and the cutter diameter and cutting width are set according to the shield cutter parameters for the corresponding working conditions; the isolated rock model is modeled based on the appearance of the isolated rock obtained from the engineering site, and the size of the isolated rock sample is set according to the corresponding working conditions.

[0008] In step S5, based on the extracted data, it is determined whether the isolated rock belongs to the overall fracturing mode, the local fracturing mode, or the non-obvious fracturing mode that is mainly characterized by movement, including: Extract the cutter force characteristics and boulder force chain evolution characteristics that reflect the boulder crushing mechanism, calculate the normal force peak-valley fluctuation coefficient, boulder crack penetration rate, and boulder centroid relative movement rate, and establish a quantitative discrimination system for three typical crushing modes. ; ; ; ; In the formula, The peak-valley fluctuation coefficient of the normal force. The average peak-to-valley difference Peak value of normal force The number of peak-trough combinations. For the first Normal force at each peak For the first A trough normal force, The penetration rate of cracks in isolated boulders. This is the vertical distance from the point of contact between the hobbing cutter and the boulder to the deepest point of the main crack. The vertical distance from the point of contact between the hobbing cutter and the boulder to the bottom of the boulder where the crack completely penetrates. The distance the center of mass of the boulder moved. This is the maximum axial dimension of the boulder. The relative mobility of the center of mass of the isolated rock.

[0009] Furthermore, the peak-valley fluctuation coefficient of the normal force of the roller cutter is used to analyze the three typical crushing modes. The penetration rate of cracks in isolated boulders Relative Motion of the Center of Mass of the Boulder As the primary quantitative criterion, auxiliary confirmation is made by combining the distribution and evolution characteristics of the internal force chains of the isolated rock, including: overall fragmentation mode, local fragmentation mode, and non-obvious fragmentation mode dominated by movement. The rapid quantitative analysis method is as follows: (1) Rapid analysis of the overall fragmentation mode; When the feature parameters extracted by numerical simulation simultaneously meet the following conditions, it is determined to be an overall fragmentation mode: a. Roller cutter stress characteristics: The extracted peak normal force of the roller cutter is the smallest compared to the other two boulder crushing modes. The stress curve exhibits non-stationary periodic fluctuations with a small peak-to-valley difference; the peak-to-valley fluctuation coefficient of the normal force is calculated from equation (1). Normal force peak-valley fluctuation coefficient The threshold is determined based on the optimal discrimination interval based on simulation results, and is adjusted in actual engineering according to the calibration model and field data; b. Crack penetration rate of isolated rocks: The crack penetration rate of isolated rocks is calculated by formula (3). The penetration rate of the cracks in the isolated rock The threshold is determined based on the optimal discrimination interval based on simulation results, and is adjusted in actual engineering according to the calibration model and field data; c. Force chain distribution characteristics: In the initial stage of crushing, particles below the cutter are compressed, forming a conical stress concentration zone where force chains concentrate, preferentially initiating microcracks. As the cutter continues to penetrate, the bonds in the core area break, the force chains are reconstructed, and stress is transferred to the surrounding area, forming the principal stress transmission path. After the cutter passes the boulder, microcracks extend along the force chains, the force chains in front of the principal cracks strengthen and disappear behind them, and secondary cracks form new branches. The force chains in the core area are completely broken into loose particles, while the force chains on the periphery remain continuous. Cracks penetrate, and the boulder is broken as a whole. The dominant factor in determining overall crushing is... Based on the characteristics of the force on the cutter and the evolution of the force chain, it was determined to be an overall fracture mode; (2) Rapid analysis of local fragmentation modes; When the feature parameters extracted by numerical simulation simultaneously meet the following conditions, it is determined to be a local fragmentation mode: a. Force characteristics of the hobbing cutter: Compared with the overall breakage of a boulder, the peak value of the normal force is significantly increased, and the fluctuation is more violent. The time for the normal force to climb from the trough to the peak value is shortened. Calculated from equation (1) ; b. Crack penetration rate and relative displacement of the isolated rock: The crack penetration rate of the isolated rock is calculated by equation (3), and the relative displacement of the isolated rock is calculated by equation (4). and Relative Motion of the Center of Mass of the Solitary Rock The threshold is determined based on the optimal discrimination interval based on simulation results, and can be adjusted in actual engineering according to the calibration model and field data.

[0010] c. Force Chain Distribution Characteristics: In the initial stage of fracturing, the high-strength rock mass inhibits the radial expansion of the force chains, causing them to concentrate mainly at the bottom of the boulders. The constraint of the bottom soil creates a local stress balance, resulting in high density and high strength of the bottom force chains. However, in the cutter contact area, due to particle breakage and bond fracture, the force chains are sparse and lighter in color. As the cutter continues to penetrate, the bottom force chains maintain high strength due to soil constraint, becoming the main path for stress transmission to the soil. As the fractured zone in the contact area expands, the force chains continuously break and reconstruct, failing to form a stable through-network. Simultaneously, the direction of the force chains shifts from vertical to the edge of the fractured zone, transferring stress to the unfractured rock mass to maintain overall structural stability. When and Based on the characteristics of the force and force chain evolution of the hobbing cutter, it was determined to be a localized fragmentation mode.

[0011] (3) Rapid analysis of the fragmentation mode dominated by movement; When the feature parameters extracted by numerical simulation simultaneously meet the following conditions, it is determined to be a non-significantly fragmented mode dominated by movement: a. Characteristics of the rolling cutter under stress: The peak normal force is the highest compared to the previous two types of isolated rock fragmentation, the stress curve is steep and accompanied by impact fluctuations; negative fluctuations appear in the later stage of rock breaking; calculated by equation (1) ; b. Crack penetration rate and relative displacement of the isolated rock: The crack penetration rate of the isolated rock can be calculated from equation (3), and the relative displacement of the isolated rock can be calculated from equation (4). and ; c. Force Chain Distribution Characteristics: In the initial stage of fracturing, because the rock mass strength far exceeds the range of the cutter's penetration force, the force chain extends radially inward from the contact point, forming a conical stress transmission structure. The force chain is concentrated directly below the cutter; only the surface particles in the contact area undergo slight fracturing, and the bond bonds are not significantly broken, so the force chain remains continuous overall. As the cutter continues to act, high-strength boulders are difficult to undergo penetrating fracturing, and the cutter force is more often converted into driving the displacement of the boulders. The force chain extends from the contact area to the edge and bottom of the boulders, forming a continuous skeleton covering the entire structure, especially densely distributed at the boulder-soil interface, indicating that the penetration force is transmitted to the interface through the force chain network, driving the boulders to overcome soil resistance and displace.

[0012] when and Based on the characteristics of the force on the hob and the evolution of the force chain, the crushing mode is determined to be mainly based on movement.

[0013] In step S5, the corresponding treatment operation is performed based on the judgment result, including: When the fracture mode is determined to be localized, the localized fracture mode is transformed into a global fracture mode by increasing the cutter penetration. The maximum normal overlap of the cutter in discrete element simulation characterizes the equivalent normal indentation depth during the contact process between the cutter and the boulder particle system; its physical meaning corresponds to the cutter penetration intensity in engineering. In actual shield tunneling, the maximum normal overlap is not directly adjusted. Instead, the equivalent penetration depth and normal intensity of the cutter on the boulder are changed by adjusting the matching relationship between the total shield thrust, penetration depth, advance speed, and cutterhead rotation speed. When the rock is determined to be in a non-significant fracturing mode dominated by movement, the soil constraint around the boulder is strengthened to transform the non-significant fracturing mode dominated by movement into a whole fracturing mode. Furthermore, the process transforms the predominantly mobile, non-significantly fractured mode into a fully fractured mode by enhancing the soil constraint around the boulder, achieved through grouting to reinforce the soil. This increases the strength parameters of the soil surrounding the boulder, thereby limiting the boulder's slippage, rolling, or deflection under the action of the cutter head.

[0014] In step S5, the treatment operation also includes: adjusting the cutterhead rotation speed, shield thrust, changing the cutter spacing, or drilling and blasting or freezing and thawing to break up the boulders.

[0015] Another objective of this invention is to provide a rapid analysis and treatment system for the fracture mode of shield tunneling cutterhead cutting boulders. This system is used to implement a rapid analysis and treatment method for the fracture mode of shield tunneling cutterhead cutting boulders. The system includes: The data acquisition module is used to acquire the boulder parameter information, shield cutter head structure parameters, and tunneling parameters of the target project, and then input the acquired parameters into the discrete element software EDEM. The model building module is used to construct an overall model of the isolated rock strata in the shield tunneling process, based on the Hertz-Mindlin with bonding V2 model and the JKR model, using the discrete element method software. The simulation analysis module is used to run simulation calculations and use the EDEM post-processing tool to extract the hob force data, boulder crack penetration rate, boulder force chain evolution characteristic map, and boulder centroid relative movement rate. The pattern determination module is used to determine, based on the extracted data, whether the isolated rock belongs to the overall fracturing mode, the local fracturing mode, or the non-obvious fracturing mode that is mainly moving. The treatment decision module is used to execute corresponding treatment operations based on the judgment results.

[0016] Combining all the above technical solutions, the beneficial effects of this invention are as follows: First, this invention, based on the Discrete Element Method (EDEM) software, focuses on the inherent fracturing characteristics of boulders and constructs an EDEM numerical model of the boulder-soil-cutter coupling system. Through numerical simulation, a large amount of data is obtained, and characteristic parameters of three typical boulder fracturing modes are identified, including differences in cutter stress characteristics, boulder fracturing degree, force chain evolution, and boulder displacement, clarifying the core distinguishing indicators for each fracturing mode. For the local fracturing and movement-dominant fracturing modes of boulders, combined with boulder parameters and cutter working parameters in actual engineering practice, influencing factors such as boulder strength, soil strength, and tunneling parameters are integrated and transformed into an overall fracturing mode. A scientifically feasible standard for judging boulder fracturing modes is established, clarifying rapid analysis and treatment methods for boulder fracturing modes under different working conditions.

[0017] Secondly, this invention does not merely perform a single simulation analysis of the boulder fracturing process, but rather forms a complete technical closed loop: engineering parameter acquisition—microscopic parameter calibration—coupling modeling of boulder-soil-roller cutter—multi-source feature extraction—fracturing mode discrimination—treatment scheme generation. Through this technical closed loop, before the tunnel boring machine (TBM) enters the boulder-affected area, it can predict three possible fracturing modes of the boulder under the action of the roller cutter: overall fracturing, partial fracturing, and non-obvious fracturing primarily involving movement. Based on the discrimination results, corresponding treatment measures can be taken, thereby improving the TBM's active control capability when traversing boulder strata.

[0018] Third, this invention establishes a coupled discrete element model of boulder-soil-roller cutter, incorporating the boulder's own fracture behavior, the constraint effect of the surrounding soil, and the cutting effect of the roller cutter into the same analytical system. This overcomes the shortcomings of traditional methods that analyze rock cutting alone or rely solely on construction experience to judge the fracturability of boulders. This model can reflect the microscopic evolution process of boulders under the action of the roller cutter, including crack propagation, local crushing, overall displacement, and force chain reconstruction, providing a calculable and reproducible analytical basis for identifying the fracture mode of boulders cut by shield tunneling roller cutters.

[0019] Fourth, this invention establishes a joint discrimination system based on the characteristics of the cutter's stress, the penetration rate of cracks in the boulder, the relative movement rate of the boulder's center of mass, and the distribution and evolution characteristics of the force chains within the boulder. Compared to existing technologies that rely solely on changes in the cutter's stress or field experience to determine whether a boulder is broken, this invention can distinguish between overall breakage caused by crack penetration, local breakage due to damage to the contact area but without penetration, and different physical processes such as the boulder sliding, rolling, or deflecting without obvious breakage. This reduces the risk of misjudging boulder movement as excessive rock strength or misjudging local breakage as overall breakage. Attached Figure Description

[0020] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with the disclosure of this invention and, together with the description, serve to explain the principles of the disclosure of this invention. Figure 1This is a flowchart of a rapid analysis and treatment method for the fracture mode of isolated boulders cut by shield tunneling cutter provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of the overall model for cutting a boulder according to an embodiment of the present invention; wherein, (a) is a front view of the overall model for cutting a boulder; (b) is a top view of the overall model for cutting a boulder; and (c) is a dimension diagram of the boulder cutting hob blade model. Figure 3 This is a graph showing the change of the normal force of the hobbing cutter over time under different boulder strength conditions provided in the embodiments of the present invention; Figure 4 This is a schematic diagram of a crack in a boulder provided in an embodiment of the present invention; Figure 5 This is a schematic diagram of the movement of a lone rock provided in an embodiment of the present invention; Figure 6 These are schematic diagrams illustrating the force chain changes in three crushing modes provided in this embodiment of the invention; (a) is a schematic diagram of the force chain of an isolated boulder when the roller cutter continuously crushes rock in the overall crushing mode; (b) is a schematic diagram of the force chain of an isolated boulder when the roller cutter continuously crushes rock in the partial crushing mode; and (c) is a schematic diagram of the force chain of an isolated boulder when the roller cutter continuously crushes rock in the moving-main crushing mode. Figure 7 This is a schematic diagram of the crack situation in the localized fracture-to-overall fracture mode provided in an embodiment of the present invention; Figure 8 This is a schematic diagram of the crack situation in the overall fracture mode with the movement as the main characteristic, provided by an embodiment of the present invention. Detailed Implementation

[0021] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0022] This invention does not simply perform numerical simulation of the process of roller cutter cutting boulders. Instead, it addresses the technical problem of "whether boulders can be effectively broken and how to promote their breakage" when a shield tunnel passes through a boulder stratum. It constructs a technical system centered on coupled analysis of the boulder, soil, and roller cutter, joint discrimination of multi-source features, and proactive transformation and treatment of breakage modes. This system incorporates the boulder's own fracture behavior, the constraint effect of the surrounding soil, and the cutting effect of the roller cutter into the same analytical framework. By extracting the roller cutter stress, crack penetration rate, relative centroid movement rate, and force chain distribution and evolution characteristics, it identifies three typical modes of boulder breakage: overall breakage, partial breakage, and non-obvious breakage mainly due to movement. Based on the discrimination results, measures such as enhancing the roller cutter effect or strengthening soil constraint are taken to transform unfavorable breakage modes into overall breakage modes. The innovation of this invention lies in: (1) A coupled analysis approach of boulder-soil-roller cutter for boulder strata is proposed. Unlike the traditional approach of simply equating boulders with continuous hard rock strata, this invention integrates boulder fracturing, soil constraint and roller cutting action into the discrete element analysis system. It can reflect the complex behaviors of boulders under the action of roller cutter, such as crack propagation, local crushing, overall slippage, rolling or deflection, and provides an analytical basis that is closer to engineering practice for the identification of boulder fracturing modes.

[0023] (2) A joint discrimination method for fracture modes based on multi-source characteristics of "force-crack-movement-chain" was established. This invention no longer relies solely on the force exerted by the cutter or on-site experience to determine whether a boulder has fractured. Instead, it uses the characteristics of the cutter's normal force, the penetration rate of cracks in the boulder, the relative movement rate of the boulder's center of mass, and the distribution and evolution characteristics of the force chains within the boulder as joint criteria to distinguish between three different physical processes: overall fracture, local fracture, and non-obvious fracture primarily due to movement. This method can reduce the risk of misjudging changes in force caused by boulder movement as excessive boulder strength or misjudging local crushing as overall fracture.

[0024] (3) A correspondence between the fracture mode of the boulder and the treatment strategy was established. For the local fracture mode, the present invention enhances the penetration effect of the cutter, adjusts the thrust, or optimizes the action parameters of the cutter to make the crack extend from the contact area of ​​the cutter to the depth of the boulder, thereby promoting the transformation of local fracture into overall fracture. For the non-obvious fracture mode that is mainly characterized by movement, the present invention strengthens the constraint of the soil around the boulder, such as by grouting to reinforce the soil, to limit the slippage, rolling or deflection of the boulder, so that the cutter load can be continuously accumulated inside the boulder and induce the formation of through cracks.

[0025] (4) A closed-loop rapid analysis process has been formed, from obtaining engineering parameters to outputting treatment solutions. This invention obtains boulder parameters, soil parameters, cutter head structure parameters, and tunneling parameters, completes the micro-parameter calibration and coupled model construction, and then extracts multi-source features and performs pattern discrimination through post-processing of simulation results, finally outputting the corresponding treatment solution. This process can be used for risk assessment before shield tunneling, optimization of tunneling parameters, and comparison of boulder treatment solutions, and is especially suitable for construction environments such as central urban areas where it is inconvenient to carry out ground drilling and blasting or excavation of maintenance wells.

[0026] Example 1, such as Figure 1 As shown, the rapid analysis and treatment method for the fracture mode of isolated boulders cut by shield tunneling cutter provided in this embodiment of the invention includes the following steps: S1. Obtain the boulder parameters, shield cutter head structure parameters, and tunneling parameters of the target project, and substitute the obtained parameters into the discrete element method software EDEM; On-site, the dimensions of the boulder were obtained through geophysical exploration and drilling; the parameters of the boulder were obtained through uniaxial and Brazilian splitting tests; the parameters of the soil were obtained through direct shear tests; and the tunneling parameters set for the tunnel boring machine were obtained. S2. Select the discrete element contact model between the boulder and the soil. The Hertz-Mindlin with bonding V2 model is used for the brittle fracture contact model of the boulder, and the JKR model is used for the discrete element contact model of the soil. S3. Based on the selected contact model, the microscopic parameters of the boulder and the soil are calibrated, and the boulder model and the soil model are established using single-size particles respectively. The parameters of the isolated rocks were calibrated by uniaxial compression tests using cylindrical rock specimens with a height of 760 mm and a diameter of 350 mm, and an average particle radius of 10 mm. Five rock materials with strength grades of 50 MPa, 70 MPa, 107 MPa, 150 MPa and 200 MPa were obtained. The parameters of the soil were calibrated by direct shear tests using cubic soil specimens of 600 mm × 600 mm × 600 mm, and an average particle radius of 10 mm.

[0027] S4. Based on the calibrated parameters and the established model, construct an overall model of the isolated rock-soil-roll cutter coupling shield tunneling isolated rock strata to form a calculation sample for the roll cutter to cut the isolated rock strata; like Figure 2 As shown in (a) and (b), the constructed roller cutter-cut boulder stratum sample has dimensions of 2000mm × 1900mm × 1100mm; the roller cutter model is located at the upper part of the center of the boulder mass, as shown in (a) and (b). Figure 2 As shown in (c), a single-edged constant-section hob with a diameter of 457 mm and a cutting width of 13.6 mm was used; the boulder sample was an ellipsoid with a major axis of 600 mm and a minor axis of 400 mm.

[0028] S5. Run simulation calculations and use EDEM post-processing tools to extract the roller cutter stress data, boulder crack penetration rate, boulder force chain evolution characteristic map, and boulder centroid relative movement rate. Based on the extracted data, determine whether the boulder belongs to the overall fracture mode, local fracture mode, or non-obvious fracture mode dominated by movement, and perform corresponding treatment operations based on the judgment results. When it is determined to be a local fracture mode, generate a treatment plan to increase the roller cutter penetration to transform the local fracture mode into an overall fracture mode. When it is determined to be a non-obvious fracture mode dominated by movement, generate a treatment plan to strengthen the soil constraint around the boulder to transform the non-obvious fracture mode dominated by movement into an overall fracture mode.

[0029] The preferred discrete element simulation platform is EDEM (Discrete Element Modeling). EDEM can establish a discrete particle system, characterizing the bond failure between isolated boulder particles, the contact constraints between soil particles, and the contact interaction between the cutter and the particle system. Simultaneously, it can output simulation results such as cutter stress, particle displacement, bond failure, and force chains between particles, meeting the needs of this invention for joint discrimination of cutter stress characteristics, crack penetration characteristics, relative displacement characteristics, and force chain evolution characteristics. This invention is not limited to EDEM software; any numerical computing platform capable of performing the above-mentioned discrete element modeling, simulation calculation, and result extraction functions can be used in this embodiment.

[0030] Crack penetration rate is extracted based on force chain distribution. The crack penetration rate and force chain evolution diagram are combined to illustrate the criterion for distinguishing the three failure modes using the force chain component. This supplements the force chain diagram, highlighting the significant differences in force chains among the three failure modes, resulting in noticeable visual differences. The force chain diagram is not the sole basis for determining the fracture mode of an isolated boulder; it is used in conjunction with quantitative indicators such as the peak-valley fluctuation coefficient of the cutter normal force, the crack penetration rate of the isolated boulder, and the relative movement rate of the boulder's centroid. Among these, the cutter stress characteristics, crack penetration rate, and relative movement rate of the centroid serve as the primary criteria, while the force chain evolution diagram helps explain the transmission path of the cutter force within the isolated boulder and at the boulder-soil interface, stress concentration areas, the bond fracture and reconstruction process, and the formation mechanism of the fracture mode. Comparative force chain diagrams for three modes—overall fracture, partial fracture, and non-obvious fracture primarily characterized by movement—have now been added. The force chain distribution patterns differ significantly among these three modes, corroborating the quantitative indicators and improving the reliability of the judgment results.

[0031] Simulation data is acquired, and characteristic parameters of three typical boulder fracturing modes are analyzed rapidly. Treatment is then carried out based on the results. The core improvement of this invention lies in step S5, which involves extracting the cutter force characteristics and boulder force chain evolution characteristics that reflect the boulder fracturing mechanism, calculating the normal force peak-valley fluctuation coefficient, boulder crack penetration rate, and relative displacement, establishing a quantitative discrimination system for the three typical fracturing modes, and proposing targeted proactive treatment methods based on this system.

[0032] The force characteristics of the cutter and the evolution characteristics of the boulder force chain, which reflect the boulder crushing mechanism, are extracted. The peak-valley fluctuation coefficient of the normal force, the crack penetration rate of the boulder, and the relative displacement rate of the boulder's center of mass are calculated to establish a quantitative discrimination system for three typical crushing modes. The peak-valley fluctuation coefficient of the cutter's normal force is used as the criterion for the three typical crushing modes. The penetration rate of cracks in isolated boulders Relative Motion of the Center of Mass of the Boulder As the primary quantitative criterion, and further confirmed by combining the distribution and evolution characteristics of the internal force chains of the isolated rock, the expression is: ; ; ; ; In the formula, The peak-valley fluctuation coefficient of the normal force. The average peak-to-valley difference Peak value of normal force The number of peak-trough combinations. For the first Normal force at each peak For the first A trough normal force, The penetration rate of cracks in isolated boulders. This is the vertical distance from the point of contact between the hobbing cutter and the boulder to the deepest point of the main crack. The vertical distance from the point of contact between the hobbing cutter and the boulder to the bottom of the boulder where the crack completely penetrates. The distance the center of mass of the boulder moved. This is the maximum axial dimension of the boulder. The relative mobility of the center of mass of the isolated rock.

[0033] The penetration rate of cracks in isolated rocks Relative Motion of the Center of Mass of the Boulder The discrimination threshold was determined based on the results of multiple sets of coupled discrete element simulations of boulder, soil, and cutter. Specifically, by changing the boulder strength, soil constraint conditions, and cutter action parameters, images of the cutter normal force response, boulder crack propagation depth, boulder centroid displacement, and force chain evolution under different working conditions were obtained, and these results were correlated with the macroscopic fracture morphology of the boulder after the simulation. The results show that when the boulder forms a through-crack and undergoes overall fracture, the crack penetration rate is usually significantly higher than that under local fracture conditions; when the boulder is only crushed or cracked near the cutter contact area, the crack penetration rate is in the middle range, and the relative centroid displacement is small; when the boulder does not form an effective crack and mainly exhibits slippage, rolling, or deflection, the crack penetration rate is close to zero, while the relative centroid displacement increases significantly.

[0034] In the typical simulation results of this embodiment, the crack penetration rate can reach 97.6% under the overall fracture mode; under the local fracture mode, the crack penetration rates corresponding to boulders of different strengths are 53.2%, 37.6%, and 29.1%, respectively, and the relative centroid movement rates are 0.0073, 0.0178, and 0.0353, respectively; under the non-significant fracture mode dominated by movement, the crack penetration rate is 0.23%, and the relative centroid movement rate is 0.221. It can be seen that the three fracture modes have obvious zoning characteristics in terms of crack penetration rate and relative centroid movement rate. Based on the above zoning characteristics, and combined with phenomena such as whether the force chain forms a penetrating failure network, whether the cutter force exhibits an impact peak and subsequent negative fluctuations, k≥70% is taken as the criterion for the overall fracture mode. and As a criterion for local fragmentation mode, take and This serves as a criterion for identifying non-obvious fragmentation modes that are primarily mobile. The aforementioned threshold is a conservative discrimination boundary determined based on the zoning characteristics of simulation results, used to reduce the risk of misjudgment between different fragmentation modes.

[0035] The three typical isolated rock fracturing modes include overall fracturing mode, local fracturing mode, and non-significant fracturing mode dominated by movement. Their quantitative and rapid analysis methods are as follows: (1) Rapid analysis of the overall fragmentation mode; When the feature parameters extracted by numerical simulation simultaneously meet the following conditions, it is determined to be an overall fragmentation mode: a. Force characteristics of hobbing cutters: such as Figure 3 As shown, the extracted peak normal force of the roller cutter is the smallest compared to the other two boulder breaking modes, and the peak normal force is the smallest. In softer soil, the peak normal force experienced by the roller cutter cutting a 50MPa boulder is approximately 130kN. In harder soil, the peak normal force is lower than in other modes. The stress curve exhibits non-stationary periodic fluctuations with small peak-to-valley differences. The peak-to-valley fluctuation coefficient of the normal force is calculated using equation (1). Normal force peak-valley fluctuation coefficient The threshold is determined based on the optimal discrimination interval based on simulation results; b. Crack penetration rate of isolated rocks: The crack penetration rate of isolated rocks is calculated by formula (3). It can be assumed that the crack completely penetrates the boulder, causing the boulder to be completely destroyed; the crack penetration rate of the boulder... The threshold is determined based on the optimal discrimination interval based on simulation results; c. Force chain distribution characteristics: In the initial stage of crushing, particles below the roller cutter are compressed, forming a conical stress concentration zone. Force chains concentrate here, preferentially initiating microcracks; such as Figure 6As shown in (a), the roller cutter continues to penetrate, causing the bonds in the core area to break, the force chain to reconstruct, and stress to transfer to the surrounding area, forming the principal stress transmission path. After the roller cutter passes the boulder, microcracks extend along the force chain, the force chain in front of the principal crack is strengthened and disappears behind it, and secondary cracks form new branches. The force chain in the core area is completely broken into loose particles, while the force chain in the periphery remains continuous. The cracks penetrate, and the boulder is broken as a whole. The dominant factor in the overall breakage is determined to be... Based on the characteristics of the rolling cutter's stress and force chain evolution, the fracture was determined to be an overall fragmentation mode; the cracks in the isolated rock resembled... Figure 4 As shown, the boulder moves as Figure 5 As shown; (2) Rapid analysis of local fragmentation modes; When the feature parameters extracted by numerical simulation simultaneously meet the following conditions, it is determined to be a local fragmentation mode: a. Force characteristics of hobbing cutters: such as Figure 3 As shown, compared to the overall breakage of the boulder, the peak value of the normal force is significantly increased, and the fluctuation is more violent; the time for the normal force to climb from the trough to the peak value is shortened, which can be calculated from equation (1). ; b. Crack penetration rate and relative displacement of isolated boulders: The crack penetration rate of isolated boulders is calculated using equation (3). The relative displacement of the isolated rock was calculated using equation (4). The crack penetration rate decreased in a stepwise manner compared to the overall fracture mode. Relative Motion of the Center of Mass of the Solitary Rock The threshold is determined based on the optimal discrimination interval based on simulation results; c. Force chain distribution characteristics: In the initial stage of fracturing, the high-strength rock mass inhibits the radial expansion of the force chains, causing them to concentrate mainly at the bottom of the boulders. The constraint of the bottom soil creates a local stress balance, resulting in high density and high strength of the force chains at the bottom. However, in the contact area of ​​the cutting cutter, due to particle breakage and bond fracture, the force chains are sparse and lighter in color; for example... Figure 6 As shown in (b), as the cutter continues to penetrate, the bottom force chain remains high due to soil constraint, becoming the main path for stress transmission to the soil; the fractured zone in the contact area expands, the force chain continuously breaks and reconstructs, failing to form a stable through-network; simultaneously, the force chain direction shifts from vertical to the edge of the fractured zone, and stress transfers to the unfractured rock mass to maintain overall structural stability; the force chain distribution exhibits asymmetrical characteristics; when and 1. Based on the characteristics of the force and force chain evolution of the hob, it was determined to be a localized fragmentation mode; (3) Rapid analysis of the fragmentation mode dominated by movement; When the feature parameters extracted by numerical simulation simultaneously meet the following conditions, it is determined to be a non-significantly fragmented mode dominated by movement: a. Force characteristics of hobbing cutters: such as Figure 3As shown, the peak normal force is the highest compared to the previous two types of boulder breakage, with a steep stress curve accompanied by impact fluctuations; the peak normal force of the 200MPa boulder exceeds 400kN, nearly 300% higher than that of the 50MPa boulder. The stress curve is steep and accompanied by impact fluctuations, and the peak-to-valley difference of the normal force under high boulder strength can reach 200-250kN. A significant negative fluctuation appears in the later stage of rock breaking, and the negative amplitude in hard soil can reach -50kN; calculated by equation (1) ; b. Crack penetration rate and relative displacement of the boulder: The crack penetration rate of the boulder is calculated by equation (3). The crack penetration rate of the 200MPa boulder was close to zero, indicating that the boulder hardly broke; the crack penetration rate was calculated by equation (4). This indicates that the fragmentation of the isolated rock was mainly due to movement. c. Force chain distribution characteristics: In the initial stage of fracturing, because the strength of the rock mass far exceeds the range of action of the cutter penetration force, the force chain extends radially inward from the contact point, forming a conical stress transmission structure. The force chain is concentrated directly below the cutter; only the surface particles in the contact area undergo slight fracturing, the bonding bonds are not significantly broken, and the force chain remains continuous overall. Figure 6 As shown in (c), with the continuous action of the cutter, the high-strength boulder is difficult to undergo penetrating breakage, and the cutter force is more converted into driving the boulder displacement; the force chain extends from the contact area to the edge and bottom of the boulder, forming a continuous skeleton covering the whole, especially densely distributed at the boulder-soil interface. The high-strength force chain shows an directional arrangement consistent with the displacement direction, indicating that the penetration force is transmitted to the interface through the force chain network, driving the boulder to overcome the soil resistance and move; this is judged as the most dangerous working condition.

[0036] In step S5, the treatment method includes: (1) Treatment for the transformation of isolated rocks from partial to overall fragmentation; While keeping all the above operating parameters unchanged, the maximum overlap in the normal direction of the hobbing cutter was increased, and the numerical simulation was repeated. The increased overlap caused more bond bonds to reach their normal strength limit instantaneously per unit time, such as... Figure 7 As shown, a penetrating fracture surface is formed inside the boulder, rather than a localized intrusion. The fracture pattern of the boulder and the embankment has undergone a fundamental change, from a localized fracture pattern to a global fracture pattern: the fracture area is no longer limited to the area directly affected by the cutter, but forms a fracture surface that penetrates the entire boulder and embankment. The fractured blocks are uniformly small, and the overall degree of fracture has been significantly improved.

[0037] (2) The treatment method shifts from primarily moving to overall fragmentation; The grouting reinforcement area preferably covers the soil region around the outer edge of the boulder within 0.3m-1.0m, and also covers the soil region in front of and on both sides of the boulder affected by cutterhead disturbance along the shield tunneling direction. When the boulder is large or the soil constraint is weak, the reinforcement area can be further expanded to 1.5m around the outer edge of the boulder. After grouting, the standard penetration test blow count, cohesion, internal friction angle, or deformation modulus of the soil around the boulder increases by 1.5 to 3.0 times compared to before grouting, or enables the soil around the boulder to reach a constraint strength that can limit the boulder's slippage, rolling, or deflection.

[0038] While keeping all the above working parameters unchanged, numerical simulations were conducted by enhancing only the soil constraints around the boulder (equivalent to replacing the softer soil parameters with harder soil parameters). The enhanced soil constraints effectively limited the lateral and cutting direction displacement of the boulder, allowing the cutting load of the hob to accumulate continuously and effectively within the boulder, such as... Figure 8 As shown, the initial crack extends continuously from the location of the cutting tool's action into the depths of the boulder, eventually forming a through crack. In actual engineering, the enhanced soil constraint around the boulder is achieved through pre-grouting reinforcement of the soil.

[0039] Example 2: The rapid analysis and treatment system for the fragmentation mode of shield tunneling cutterhead cutting boulders provided in this embodiment of the invention includes: The data acquisition module is used to acquire the boulder parameter information, shield cutter head structure parameters, and tunneling parameters of the target project, and then input the acquired parameters into the discrete element software EDEM. The model building module is used to construct an overall model of the isolated rock strata in the shield tunneling process, based on the Hertz-Mindlin with bonding V2 model and the JKR model, using the discrete element method software. The simulation analysis module is used to run simulation calculations and use the EDEM post-processing tool to extract the hob force data, boulder crack penetration rate, boulder force chain evolution characteristic map, and boulder relative displacement. The pattern determination module is used to determine, based on the extracted data, whether the isolated rock belongs to the overall fracturing mode, the local fracturing mode, or the non-obvious fracturing mode that is mainly moving. The treatment decision module is used to execute corresponding treatment operations based on the judgment results.

[0040] In Example 3, regarding treatment methods, in addition to "increasing the maximum normal overlap" and "advanced grouting", the same purpose can be achieved by adjusting the cutterhead speed, shield thrust, or changing the cutter spacing. Alternatively, the isolated rock can be broken by drilling and blasting or by cold and hot freeze-thaw cycles.

[0041] To further demonstrate the positive effects of the above embodiments, this invention explains the rationality of the technical solution based on existing theories of roller cutter rock breaking, full-size linear cutting tests, rotary cutting tests, confining pressure constraint tests, and penetration influence tests. The force on the roller cutter is related to the rock strength, the roller cutter's geometric parameters, penetration, and cutter spacing; crack propagation and penetration are important indicators of overall crushing; surrounding constraints affect the transformation of rock from slippage and extrusion to crushing failure; enhancing the roller cutter's penetration and strengthening surrounding constraints both have existing theoretical and experimental foundations. Existing theories on cutter rock breaking indicate that the rock-breaking force of the cutter is closely related to parameters such as rock compressive strength, tensile strength, cutter diameter, cutting edge width, penetration depth, and cutter spacing. CSM, Rostami, and other cutter stress prediction models all use rock mechanical parameters and cutter geometric parameters as important inputs for calculating the cutter normal force, tangential force, and rock-breaking efficiency. These existing models typically use parameters such as uniaxial compressive strength, Brazilian splitting tensile strength, cutter spacing, penetration depth, cutter diameter, and cutting edge width to calculate the single-cutter load. Therefore, this invention obtains the mechanical parameters of the boulder, the cutter structural parameters, and the tunnel boring machine parameters in its method, and uses these as the basic inputs for analyzing the boulder breaking mode, which aligns with the understanding of control parameters in cutter rock breaking theory.

[0042] Existing full-scale linear cutting and rotary cutting tests have shown that cutter penetration, cutter spacing, rock strength, and boundary constraints significantly affect cutter stress, fragment formation, and rock-breaking efficiency. Current research indicates that full-scale linear cutting, rotary cutting, and small-scale TBM tests are important experimental methods for determining cutter penetration, cutter spacing, and cutting geometry parameters. Linear cutting tests, in particular, can better account for scale effects, and their results can be used to evaluate TBM performance in practical engineering. Other studies have shown that full-scale cutter cutting tests typically use large-sized rock blocks and actual-sized cutters, considering actual cutter spacing and penetration, thus providing a more realistic reflection of the mechanical behavior of the TBM cutter and cutterhead. This demonstrates that this invention, which uses cutter stress, penetration, crack propagation, and fragmentation morphology as criteria for fragmentation mode discrimination, has an existing experimental foundation.

[0043] From the perspective of the crushing mechanism, existing studies generally agree that rock failure under the action of roller cutters is mainly related to shear failure and tensile crack propagation. The propagation and penetration of cracks between adjacent roller cutters or adjacent cutting grooves are important reasons for the formation of effective block fragmentation. Existing bidirectional confined pressure roller cutter indentation tests have shown that confined pressure conditions significantly affect the fracture surface morphology, fragmentation volume, and rock-breaking efficiency. When the constraint state changes, the failure mode can transform from shallow shear failure to bottom tensile failure, and the crushing efficiency also changes accordingly. Therefore, this invention uses crack penetration rate as an important criterion for overall and local crushing, and uses force chain transmission and fracture conditions to assist in judging crack propagation path, which conforms to the basic mechanism of "crack propagation - crack penetration - block formation" in roller cutter rock breaking.

[0044] Existing constrained tests also show that lateral constraints alter the failure morphology of rocks under the action of a cutting roller. For example, linear cutting tests of extremely hard diorite by a cutting roller show that under lateral constraints, rock failure is more likely to shift from slip and extrusion to crushing; while under unconstrained conditions, the rock is more prone to lateral spalling, and the distance of rock fragment ejection increases with increasing penetration. This pattern has the same mechanical implications as the boulder problem addressed in this invention: when the soil constraint around the boulder is insufficient, the energy input from the cutting roller is easily converted into boulder slippage, rolling, or deflection; when the surrounding constraint is enhanced, the cutting roller load is more likely to accumulate inside the boulder, promoting crack propagation and overall fragmentation. Therefore, this invention proposes to promote the transformation to overall fragmentation by enhancing the constraint of the surrounding soil in a non-significant fragmentation mode dominated by movement, which is supported by existing experimental data.

[0045] Existing cutter cutting tests have shown that increasing penetration depth increases the cutter's normal force and alters rock-breaking efficiency. However, beyond a certain range, simply increasing penetration depth does not always significantly improve rock-breaking efficiency. In relevant cutter cutting tests on extremely hard rock, the normal force increases with penetration depth, and there exists an optimal penetration range. This indicates that for locally fractured modes, the cracks should be encouraged to extend deeper by moderately enhancing cutter penetration, adjusting thrust, or optimizing cutter spacing, rather than indiscriminately increasing tunneling parameters. This invention correlates locally fractured modes with treatment measures that enhance cutter penetration, consistent with the relationship between cutter penetration depth and rock-breaking efficiency observed in existing tests.

[0046] Existing theories on rock breaking with roller cutters, full-scale roller cutter cutting tests, confining pressure tests, and penetration influence tests all demonstrate that the rock breaking process is jointly controlled by rock strength, roller cutter geometry, penetration, cutter spacing, and boundary constraint conditions. Crack propagation and penetration are key to overall fragmentation. Insufficient constraints make the rock mass more prone to slippage, spalling, or non-penetrating failure. Enhancing constraints and rationally adjusting roller cutter parameters can alter the fragmentation morphology. These theoretical and experimental findings align with the technical approach proposed in this invention: "coupled analysis of isolated rocks, soil, and roller cutters; joint discrimination of force-crack-movement-chain multi-source characteristics; and transformation from localized fragmentation or movement-dominant modes to overall fragmentation." This demonstrates the rationality and engineering feasibility of the invention's technical solution from both theoretical and experimental perspectives.

[0047] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications, equivalent substitutions and improvements made by those skilled in the art within the scope of the technology disclosed in the present invention and within the spirit and principles of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A rapid analysis and treatment method for the fracture mode of isolated boulders cut by shield tunneling cutterheads, characterized in that, The method includes the following steps: S1. Obtain the boulder parameters, shield cutter head structure parameters, and tunneling parameters of the target project, and substitute the obtained parameters into the discrete element method software EDEM; S2. Select the discrete element contact model between the boulder and the soil. The Hertz-Mindlin with bonding V2 model is used for the brittle fracture contact model of the boulder, and the JKR model is used for the discrete element contact model of the soil. S3. Based on the selected contact model, the microscopic parameters of the boulder and the soil are calibrated, and the boulder model and the soil model are established using single-size particles respectively. S4. Based on the calibrated parameters and the established model, construct an overall model of the isolated rock-soil-roll cutter coupling shield tunneling isolated rock strata to form a calculation sample for the roll cutter to cut the isolated rock strata; S5. Run simulation calculations and use EDEM post-processing tools to extract the roller cutter stress data, boulder crack penetration rate, boulder force chain evolution characteristic map, and boulder centroid relative movement rate. Based on the extracted data, determine whether the boulder belongs to the overall fracture mode, local fracture mode, or non-obvious fracture mode dominated by movement, and perform corresponding treatment operations based on the judgment results. When it is determined to be a local fracture mode, generate a treatment plan to increase the roller cutter penetration to transform the local fracture mode into an overall fracture mode. When it is determined to be a non-obvious fracture mode dominated by movement, generate a treatment plan to strengthen the soil constraint around the boulder to transform the non-obvious fracture mode dominated by movement into an overall fracture mode.

2. The rapid analysis and treatment method for the fracture mode of isolated boulders cut by shield tunneling cutterheads according to claim 1, characterized in that, In step S1, the boulder parameters include: the boulder's size and appearance obtained through geophysical exploration and drilling; The shield cutterhead structural parameters include the cutterhead dimensions; The tunneling parameters include the penetration depth and cutterhead rotation speed set by the tunnel boring machine.

3. The rapid analysis and treatment method for the fracture mode of isolated boulders cut by shield tunneling cutterheads according to claim 1, characterized in that, In step S3, the micro-parameters of the boulder and the soil are calibrated according to the selected contact model, including: the micro-parameters of the boulder are calibrated by uniaxial compression test and Brazilian splitting test, and the micro-parameters of the soil are calibrated by direct shear test.

4. The rapid analysis and treatment method for the fracture mode of isolated boulders cut by shield tunneling cutterheads according to claim 1, characterized in that, In step S4, forming a calculation sample for cutting isolated rock formations with a cutter head includes: constructing a corresponding calculation sample for cutting isolated rock formations with a cutter head based on the shield cutter head structure parameters and tunneling parameters obtained from different engineering sites; the cutter head model is located at the upper center of the isolated rock mass, and the cutter head diameter and cutting edge width are set according to the shield cutter head parameters for the corresponding working conditions; the isolated rock model is modeled based on the appearance of the isolated rock obtained from the engineering site, and the size of the isolated rock sample is set according to the corresponding working conditions.

5. The rapid analysis and treatment method for the fracture mode of isolated boulders cut by shield tunneling cutterheads according to claim 1, characterized in that, In step S5, based on the extracted data, it is determined whether the isolated rock belongs to the overall fracturing mode, the local fracturing mode, or the non-obvious fracturing mode that is mainly characterized by movement, including: The force characteristics of the cutter and the evolution characteristics of the boulder force chain, which reflect the boulder crushing mechanism, are extracted. The peak-valley fluctuation coefficient of the normal force, the crack penetration rate of the boulder, and the relative displacement rate of the boulder's center of mass are calculated to establish a quantitative discrimination system for three typical crushing modes. The peak-valley fluctuation coefficient of the cutter's normal force is used as the criterion for the three typical crushing modes. The penetration rate of cracks in isolated boulders Relative Motion of the Center of Mass of the Boulder As the primary quantitative criterion, and further confirmed by combining the distribution and evolution characteristics of the internal force chains of the isolated rock, the expression is: （1） （2） （3） （4） In the formula, The peak-valley fluctuation coefficient of the normal force. The average peak-to-valley difference Peak normal force The number of peak-trough combinations. For the first Normal force at each peak For the first A trough normal force, The penetration rate of cracks in isolated boulders. This is the vertical distance from the point of contact between the hobbing cutter and the boulder to the deepest point of the main crack. The vertical distance from the point of contact between the hobbing cutter and the boulder to the bottom of the boulder where the crack completely penetrates. The distance the center of mass of the boulder moved. This is the maximum axial dimension of the boulder. The relative mobility of the center of mass of the isolated rock.

6. The rapid analysis and treatment method for the fracture mode of isolated boulders cut by shield tunneling cutterheads according to claim 5, characterized in that, The following are three typical rapid quantitative analysis methods for fracture modes: (1) Rapid analysis of the overall fragmentation mode; When the feature parameters extracted by numerical simulation simultaneously meet the following conditions, it is determined to be an overall fragmentation mode: a. Roller cutter stress characteristics: The extracted peak normal force of the roller cutter is the smallest compared to the other two boulder crushing modes; the stress curve exhibits non-stationary periodic fluctuations with small peak-to-valley differences; the peak-to-valley fluctuation coefficient of the normal force is calculated from equation (1). ; b. Crack penetration rate of isolated rocks: The crack penetration rate of isolated rocks is calculated by formula (3). ; c. Force chain distribution characteristics: In the initial stage of crushing, particles below the cutter are compressed, forming a conical stress concentration zone where force chains concentrate, preferentially initiating microcracks. As the cutter continues to penetrate, the bonds in the core area break, the force chains are reconstructed, and stress is transferred to the surrounding area, forming the principal stress transmission path. After the cutter passes the boulder, microcracks extend along the force chains, the force chains in front of the principal cracks strengthen and disappear behind them, and secondary cracks form new branches. The force chains in the core area are completely broken into loose particles, while the force chains on the periphery remain continuous. Cracks penetrate, and the boulder is broken as a whole. The dominant factor in determining overall crushing is... Based on the characteristics of the force on the cutter and the evolution of the force chain, it was determined to be an overall fracture mode; (2) Rapid analysis of local fragmentation modes; When the feature parameters extracted by numerical simulation simultaneously meet the following conditions, it is determined to be a local fragmentation mode: a. Force characteristics of the hobbing cutter: Compared with the overall breakage of a boulder, the peak value of the normal force is significantly increased, and the fluctuation is more violent; the time for the normal force to climb from the trough to the peak value is shortened, which can be calculated by equation (1). ; b. Crack penetration rate and relative displacement of the isolated rock: The crack penetration rate of the isolated rock is calculated by equation (3), and the relative displacement of the isolated rock is calculated by equation (4). and ; c. Force Chain Distribution Characteristics: In the initial stage of fracturing, the high-strength rock mass inhibits the radial expansion of the force chains, causing them to concentrate mainly at the bottom of the boulders. The constraint of the bottom soil creates a local stress balance, resulting in high density and high strength of the bottom force chains. In contrast, the force chains in the cutter contact area are sparse and lighter in color due to particle breakage and bond fracture. As the cutter continues to penetrate, the bottom force chains maintain high strength due to soil constraint, becoming the main path for stress transmission to the soil. As the fractured zone in the contact area expands, the force chains continuously break and reconstruct, failing to form a stable through-network. Simultaneously, the direction of the force chains shifts from vertical to the edge of the fractured zone, transferring stress to the unfractured rock mass to maintain overall structural stability. When and Based on the characteristics of the force and force chain evolution of the hob, it was determined to be a localized fragmentation mode; (3) Rapid analysis of the fragmentation mode dominated by movement; When the feature parameters extracted by numerical simulation simultaneously meet the following conditions, it is determined to be a non-significantly fragmented mode dominated by movement: a. Characteristics of the rolling cutter under stress: The peak normal force is the highest compared to the previous two types of isolated rock fragmentation, the stress curve is steep and accompanied by impact fluctuations; negative fluctuations appear in the later stage of rock breaking; calculated by equation (1) ; b. Crack penetration rate and relative displacement of the isolated rock: The crack penetration rate of the isolated rock is calculated by equation (3), and the relative displacement of the isolated rock is calculated by equation (4). and ; c. Force Chain Distribution Characteristics: In the initial stage of fracturing, because the rock mass strength far exceeds the range of the cutter's penetration force, the force chain extends radially inward from the contact point, forming a conical stress transmission structure. The force chain is concentrated directly below the cutter; only the surface particles in the contact area undergo slight fracturing, and the bond bonds are not significantly broken, so the force chain remains continuous overall. As the cutter continues to act, high-strength boulders are difficult to undergo penetrating fracturing, and the cutter force is more often converted into driving the displacement of the boulders. The force chain extends from the contact area to the edge and bottom of the boulders, forming a continuous skeleton covering the entire structure. It is densely distributed at the boulder-soil interface, indicating that the penetration force is transmitted to the interface through the force chain network, driving the boulders to overcome soil resistance and move. When and Based on the characteristics of the force on the hob and the evolution of the force chain, the crushing mode is determined to be mainly based on movement.

7. The rapid analysis and treatment method for the fracture mode of isolated boulders cut by shield tunneling cutterheads according to claim 6, characterized in that, In step S5, the corresponding treatment operation is performed based on the judgment result, including: When the condition is determined to be a localized crushing mode, the localized crushing mode is transformed into a generalized crushing mode by increasing the penetration force of the roller cutter. When the rock is determined to be in a non-significant fracturing mode dominated by movement, the non-significant fracturing mode dominated by movement can be transformed into an overall fracturing mode by strengthening the soil constraint around the boulder.

8. The rapid analysis and treatment method for the fracture mode of isolated boulders cut by shield tunneling cutterheads according to claim 7, characterized in that, By enhancing the soil constraint around the boulder, the non-significant fracturing mode dominated by movement is transformed into an overall fracturing mode. This is achieved by grouting to reinforce the soil, thereby increasing the strength parameters of the soil around the boulder and limiting the boulder's slippage, rolling, or deflection under the action of the cutter head.

9. The rapid analysis and treatment method for the fracture mode of isolated boulders cut by shield tunneling cutterheads according to claim 7, characterized in that, The corresponding treatment operations based on the judgment results also include: adjusting the cutterhead speed, shield thrust, changing the cutter spacing, or drilling and blasting or freezing and thawing to break up boulders.

10. A rapid analysis and treatment system for the fracture mode of isolated boulders cut by shield tunneling cutterheads, characterized in that, This system is used to implement a rapid analysis and treatment method for the fracture mode of shield tunneling cutterhead cutting boulders as described in any one of claims 1-9. The system includes: The data acquisition module is used to acquire the boulder parameter information, shield cutter head structure parameters, and tunneling parameters of the target project, and then input the acquired parameters into the discrete element software EDEM. The model building module is used to construct an overall model of the isolated rock strata in the shield tunneling process, based on the Hertz-Mindlin with bonding V2 model and the JKR model, using the discrete element method software. The simulation analysis module is used to run simulation calculations and use the EDEM post-processing tool to extract the hob force data, boulder crack penetration rate, boulder force chain evolution characteristic map, and boulder centroid relative movement rate. The pattern determination module is used to determine, based on the extracted data, whether the isolated rock belongs to the overall fracturing mode, the local fracturing mode, or the non-obvious fracturing mode that is mainly moving. The treatment decision module is used to execute corresponding treatment operations based on the judgment results.

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