A collaborative advance active reinforcement method for TBM tunneling

Abstract

This invention relates to the field of tunnel engineering construction technology and discloses a synergistic proactive reinforcement method for TBM excavation. The method includes acquiring geological information of the surrounding rock ahead of the excavation face, formulating a drilling plan based on the length of the pre-treatment area, and drilling using an onboard drilling rig or directional drilling rig. A waveguide is inserted into the borehole, and a microwave generator is activated to radiate the surrounding rock, inducing a network of interconnected fractures within the rock mass using thermal stress. After cleaning the borehole, a grouting pipe is inserted and sealed, and chemical grout is injected. The grout permeates along the fracture network and solidifies within a predetermined time, cementing the fractured rock mass to form an artificial and natural composite roof support structure. The TBM cutterhead then excavates under the protection of this composite structure. This invention utilizes the synergistic effect of microwave fracturing and grouting modification to solve the problems of difficult grouting in low-permeability surrounding rock and the lag of traditional support methods, thereby improving roof stability and excavation safety.

Description

Technical Field

[0001] This invention relates to the field of tunnel engineering construction technology, specifically to a collaborative advanced active reinforcement method for TBM excavation. Background Technology

[0002] Full-face tunnel boring machines (TBMs) are widely used in deep underground engineering construction, but when crossing complex geological sections such as fault fracture zones, weak rock layers or water-bearing strata, the stability control of the surrounding rock faces severe challenges.

[0003] When dealing with rock masses that are low-permeability or dense with well-developed microfractures, traditional grouting reinforcement techniques are often limited by the pore structure of the rock mass itself. The diffusion resistance of grout in dense rock strata is high, making it difficult to effectively penetrate deeper. This results in grout accumulating only around the borehole or fracturing and flowing away along dominant fractures, failing to form a uniform and effective reinforcement zone within the rock mass and thus hindering the grouting challenges in low-permeability formations.

[0004] Furthermore, traditional TBM construction often employs passive support methods, with support work lagging behind the excavation face and only being addressed after the surrounding rock is exposed. For loose, fractured, or soft rock formations with high ground stress, delayed support cannot effectively limit the initial deformation of the surrounding rock, easily leading to collapse or spalling of the roof rock mass in front of the cutterhead, and consequently, machine jamming accidents. Even with conventional pre-grouting methods, if the grout cannot adequately fill the rock fissures and increase the cohesion and internal friction angle of the surrounding rock, it is difficult to form a stable, self-supporting structure.

[0005] Meanwhile, existing advanced reinforcement technologies typically employ a single, fixed construction model, lacking adaptability to different geological hazard ranges. When facing adverse geological sections of varying lengths, the inability to flexibly adjust drilling and remediation plans often results in excessively long reinforcement operation cycles. The cumbersome drilling and grouting processes consume a significant amount of TBM operation time, causing prolonged equipment downtime and hindering the continuous and efficient tunneling rhythm of full-face tunnel boring machines. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a collaborative and proactive reinforcement method for TBM tunneling, which solves the problem that when a full-face tunnel boring machine (TBM) is tunneling under complex geological conditions, traditional support lags behind the deformation of the surrounding rock, and grouting is difficult in low-permeability surrounding rock, which can easily lead to collapse or machine jamming at the tunneling face.

[0007] To achieve the above objectives, the present invention is implemented through the following technical solution: a collaborative advanced active reinforcement method for TBM tunneling, which constructs an artificial and natural composite roof support structure in front of the TBM cutterhead through the collaborative operation of microwave thermal fracturing and permeability enhancement and chemical grouting modification.

[0008] The technical solution adopted in this invention is as follows:

[0009] The geological information of the surrounding rock in front of the tunnel face is obtained by using the detection equipment integrated on the full-face tunnel boring machine. Based on the geological information, a drilling layout plan and modification process parameters are formulated, and drilling construction is carried out to form boreholes.

[0010] After the drilling is completed, a waveguide is inserted into the borehole, and a microwave generator is activated to radiate microwave energy to the surrounding rock around the borehole. The dielectric heating effect of microwaves on rock minerals induces a network of interconnected fractures within the surrounding rock. After the operation is completed, fluid is used to clean the inside of the borehole to remove rock debris generated by thermal disintegration.

[0011] The grouting pipe is inserted into the cleaned borehole, and the predetermined section of the borehole is sealed using a sealing device. The grouting pressure pump is started to inject chemical grout into the borehole. The chemical grout penetrates along the fracture network under the grouting pressure and capillary action.

[0012] The chemical slurry reacts and solidifies within a predetermined time, cementing the broken rock mass to form an artificial and natural composite roof support structure with a certain strength; the cutterhead of the full-face tunnel boring machine performs tunneling operations under the protection of the artificial and natural composite roof support structure, cutting the modified rock mass.

[0013] Preferably, the specific process for formulating the borehole layout scheme includes: determining the longitudinal length of the advanced treatment area based on the geological information; if the longitudinal length is less than a preset length threshold, it is determined to be the first case; if the longitudinal length is greater than or equal to the preset length threshold, it is determined to be the second case, wherein the preset length threshold is 10m; when it is determined to be the first case, an airborne drilling rig arranged on the drilling platform of the full-face tunnel boring machine is used to construct advanced boreholes; when it is determined to be the second case, a directional drilling rig is used to construct directional boreholes along the design trajectory; the advanced boreholes constructed by the airborne drilling rig or the directional boreholes constructed by the directional drilling rig serve as physical channels for subsequent microwave intervention and grouting.

[0014] Preferably, the chemical slurry is a composite slurry of nano-silica sol and water glass; the initial viscosity of the prepared chemical slurry is less than 30 mPa·s to adapt to the microcrack scale induced by microwave; the predetermined time in the modification process parameters is set to 30-120 s, during which the chemical slurry solidifies to form a silica-calcium cement.

[0015] Preferably, the microwave generator includes a microwave source connected to a power switch and a control device. The power switch connects or disconnects the power supply to the microwave source, and the control device adjusts the output power and operating time of the microwave source. A circulator is installed on the output path of the microwave source to unidirectionally isolate the transmitted microwave energy and guide the microwave energy reflected back from the rock mass to a cooling fluid circulation device for absorption, preventing reflected waves from damaging the microwave source. A detector is installed in the circuit of the microwave generator to detect the incident and reflected currents of the microwaves in real time.

[0016] Preferably, the control device sets the output power density of the microwave source to 0.5-2.0 W / cm². 3 The single irradiation time is set to 30-120s; a backward segmented processing technology is adopted for the directional borehole; after the waveguide extends into the bottom of the hole, it moves from the bottom of the hole to the opening in the directional borehole, and the microwave energy is radiated in a backward segmented manner to ensure that the rock mass along the borehole axis is continuously covered.

[0017] Preferably, the microwave source is used to emit electromagnetic waves at a frequency of 915MHz or 2450MHz; the microwave energy in this frequency band is absorbed by the fissure water and clay minerals in the surrounding rock, causing the water inside the rock mass to vaporize and the mineral lattice to expand differentially; when the stress generated by the expansion exceeds the tensile strength of the rock matrix, tensile thermal stress is generated at the mineral grain boundaries and fissure tips of the surrounding rock, thereby causing the rock mass to undergo volumetric fracture and form three-dimensional interconnected fissures.

[0018] Preferably, the waveguide tail is provided with a threaded interface for connecting to the output end or transmission component of the microwave generator; a microwave hole is drilled in the front wall of the waveguide as a window for emitting microwave energy outward; the microwave hole is covered with a wave-transparent dielectric protective plate, which is used to block water vapor and rock debris from entering the interior of the waveguide, while allowing the microwave energy to penetrate and radiate to the rock mass.

[0019] Preferably, the sealing device is installed on the grouting pipe. The sealing device is used to expand radially to seal the borehole opening, or to expand within the borehole to isolate the borehole in sections. For the directional borehole, a backward segmented grouting process is adopted. The sealing device and the grouting pipe move from the bottom of the borehole to the opening within the directional borehole, and the chemical grout is injected into different depth regions of the directional borehole in a backward segmented manner.

[0020] Preferably, the grouting pressure pump is connected to a drive motor, which provides power output to the grouting pressure pump; the grouting pressure pump is also equipped with a grout inlet and a pressure gauge, which displays the grouting pressure; the output end of the grouting pressure pump is connected to one end of the grouting hose via a connector, and the other end of the grouting hose is connected to the grouting pipe, and the chemical grout is ejected through the grout outlet on the wall of the grouting pipe.

[0021] Preferably, in the step of cleaning the borehole interior and the fracture network with fluid, the fluid is selected from either high-pressure air or water flow, and is used to clear the fracture channels generated by microwave fracturing; the cutterhead of the full-face tunnel boring machine cuts the modified surrounding rock, and after the TBM passes through, permanent support construction is carried out in the excavated area to complete a reinforcement and excavation cycle.

[0022] This invention, through the aforementioned technical solution, utilizes the selective heating characteristics of microwaves on water and sensitive minerals in rocks to induce a network of micron- to millimeter-scale fractures in low-permeability rock masses, solving the problem of difficult grout penetration. Subsequently, a low-viscosity, fast-setting chemical grout is injected to fill the microwave-induced fractures and cement the loose rock mass. This synergistic effect of physical fracturing and chemical cementation transforms the unstable surrounding rock ahead of the working face into a robust, high-bearing-capacity artificial-natural composite roof before TBM excavation, ensuring continuous TBM excavation.

[0023] This invention provides a collaborative, proactive, and advanced reinforcement method for TBM tunneling. It offers the following advantages:

[0024] 1. This invention utilizes microwave-directed irradiation fracturing technology to generate uneven thermal stress within the rock mass by exploiting differences in the dielectric loss of minerals in the rock, thereby inducing a network of interconnected fractures in low-permeability or dense surrounding rocks. This physical modification method directly alters the microscopic pore structure of the rock mass, overcoming the technical bottleneck of traditional grouting processes where grout cannot diffuse in low-permeability formations, and providing the necessary physical channels for the deep penetration of subsequent chemical grouts.

[0025] 2. This invention utilizes a low-viscosity nano-silica sol composite grout, matched with microwave-induced fractures, to fill microwave-induced thermal stress fractures by leveraging the grout's rapid setting and high permeability. The silica-calcium cement formed after the grout solidifies re-bonds the loose and fractured rock mass, increasing the cohesion and internal friction angle of the surrounding rock. This constructs a highly integrated artificial and natural composite roof in front of the TBM cutterhead, effectively reducing the risk of collapse during tunneling.

[0026] 3. This invention achieves precise coverage of advanced treatment areas at different scales ahead of the tunnel boring machine by using a graded drilling construction and retreating segmented operation scheme based on geological exploration information. The flexible switching between long-distance directional drilling and short-distance advanced drilling, combined with the rapid collaborative operation of microwave and grouting, enables the advanced reinforcement process to adapt to the continuous operation rhythm of the full-face tunnel boring machine, reducing the long downtime of equipment due to surrounding rock treatment. Attached Figure Description

[0027] Figure 1 This is a flowchart of a collaborative advanced active reinforcement method for TBM tunneling according to an embodiment of the present invention;

[0028] Figure 2 This is a schematic diagram of the system layout when a full-face tunnel boring machine (TBM) is used to lay out advanced boreholes and perform microwave fracturing in an embodiment of the present invention.

[0029] Figure 3 This is a schematic diagram of the system layout for chemical grouting of advanced boreholes in an embodiment of the present invention;

[0030] Figure 4 This is a schematic diagram of the system layout when using a directional drilling rig to arrange directional boreholes and perform microwave fracturing in an embodiment of the present invention;

[0031] Figure 5 This is a schematic diagram of the system layout for chemical grouting during directional drilling in an embodiment of the present invention;

[0032] Figure 6 This is a schematic diagram of the structure of the microwave-directed fracturing and permeation-enhancing subsystem in an embodiment of the present invention;

[0033] Figure 7 This is a schematic diagram of the structure of the chemical grouting modification subsystem in an embodiment of the present invention;

[0034] Figure 8 for Figure 2 Enlarged diagram of point A in the middle.

[0035] Among them, 1. Waveguide; 2. Detector; 3. Coolant circulation device; 4. Microwave generator; 5. Circulator; 6. Power switch; 7. Cutterhead; 8. Drilling platform; 9. Grouting pipe; 10. Connector; 11. Grout inlet; 12. Pressure gauge; 13. Drive motor; 14. Grouting pressure pump; 15. Directional drilling; 16. Threaded interface; 17. Microwave hole; 18. Medium guard plate; 19. Control device; 20. Grout outlet; 21. Sealing device; 22. Grouting hose; 23. Advance drilling. Detailed Implementation

[0036] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0037] See attached document Figure 1 -Appendix Figure 8 This invention provides a collaborative advanced active reinforcement method for TBM tunneling. The collaborative advanced active reinforcement system is integrated into the drilling platform 8 of the full-face tunnel boring machine (TBM) and includes a geological advance prediction and decision-making subsystem, a microwave directional fracturing and permeability enhancement subsystem, and a chemical grouting modification subsystem.

[0038] The geological advance prediction and decision-making subsystem is configured to acquire geological information of the surrounding rock ahead of the tunneling face. Based on the length of the advance treatment area obtained from advance detection, the subsystem generates construction decisions: determining the longitudinal length of the advance treatment area based on geological information, classifying the longitudinal length as less than a preset length threshold as the first case (shorter advance treatment area), and classifying the longitudinal length as greater than or equal to the preset length threshold (longer advance treatment area) as the second case. In this embodiment, the preset length threshold is set to 10m. When the first case is identified (i.e., longitudinal length < 10m), the decision calls the full-face tunnel boring machine's onboard drilling rig to construct advance borehole 23; when the second case is identified (i.e., longitudinal length ≥ 10m), the decision calls the directional drilling rig to construct directional borehole 15. Advance borehole 23 and directional borehole 15 are collectively referred to as boreholes in subsequent embodiments. Meanwhile, the geological advanced prediction and decision-making subsystem intelligently matches the output power density, irradiation time, grout ratio, and grouting pressure parameters of the microwave generator 4 based on the detected lithology and water-bearing state.

[0039] See attached document Figure 5 The microwave-directed fracturing and permeability enhancement subsystem is used to induce a thermal stress fracture network within the rock mass. The subsystem mainly consists of a power switch 6, a microwave source, a control device 19, a waveguide assembly, and a cooling and protection unit. The microwave source uses an industrial-grade high-power magnetron, configured to generate high-frequency electromagnetic waves to ensure sufficient penetration depth into the rock mass. The microwave source is connected to the waveguide 1 via a transmission assembly to transmit microwave energy to the front end. The waveguide 1 has a threaded interface 16 at its tail end for connecting to the output end of the microwave generator 4; a microwave aperture 17 is drilled at the front end of the waveguide 1 as a microwave energy emission window. To prevent rock cuttings, dust, and water vapor from flowing back into the waveguide 1, the microwave aperture 17 is covered with a wave-transparent dielectric protective plate 18.

[0040] See attached document Figure 6 The chemical grouting modification subsystem is used to inject reinforcing materials into microwave-fractured rock masses. The subsystem includes a grouting pressure pump 14, a grouting pipe 9, a sealing device 21, and a two-component mixer. The grouting pressure pump 14 is configured to pressurize and pump the two-component grout. The grouting pipe 9 is designed as a tubular structure that extends deep into the bottom of the borehole, with grout outlets 20 arranged on its body. The sealing device 21 is installed on the grouting pipe 9 to seal the borehole opening or section, preventing grout leakage. The grout used in the chemical grouting modification subsystem is a composite grout of nano-silica sol and water glass, which has low viscosity and rapid setting characteristics, and the solidified body possesses high compressive strength.

[0041] Reference Appendix Figure 1 Based on the aforementioned collaborative proactive reinforcement system, the collaborative proactive reinforcement operation process implemented in this embodiment of the invention includes the following steps:

[0042] Step S1: Intelligent perception and parameter decision-making of the rock mass condition ahead of the tunnel face. Geological information ahead is obtained through advanced geological prediction technology. If the length of the area to be treated ahead is determined to be short (longitudinal length less than a preset length threshold), advance boreholes 23 are arranged using a full-face tunnel boring machine (TBM) onboard drilling rig; if the area to be treated is determined to be long (longitudinal length greater than or equal to the preset length threshold), directional boreholes 15 are arranged using a directional drilling rig. Operating parameters such as microwave power density and irradiation duration are set based on the content of sensitive minerals such as montmorillonite and the water content in the rock mass.

[0043] Step S2: Microwave-Directed Irradiation for Fracture Induction and Permeability Enhancement. After drilling is completed, the rock cuttings inside the borehole are cleaned. The waveguide 1 is inserted into the borehole to the predetermined depth, and the microwave generator 4 is activated. Microwave energy penetrates the dielectric protective plate 18 and radiates to the surrounding rock through the microwave aperture 17. The fissure water and clay minerals in the rock mass selectively absorb the microwave energy, generating volume expansion and thermal stress, inducing a three-dimensional interconnected fracture network at the micron to millimeter scale. For the directional borehole 15, a retreating segmented treatment process is adopted, that is, after irradiation for a predetermined time at the bottom of the hole, the waveguide 1 is retreated a certain distance for irradiation again until the entire target area is covered. After the operation is completed, the microwave source is turned off and the waveguide 1 is retrieved. Then, high-pressure air or water is used to perform a secondary cleaning of the borehole interior and the microwave-induced new fractures to remove rock cuttings and dust generated by thermal disintegration and ensure the unobstructed grouting channel.

[0044] Step S3: Chemical grouting and bonding. The grouting pipe 9 is inserted into the microwave-treated borehole, and the borehole is sealed using the sealing device 21. The grouting pressure pump 14 is started, injecting the nano-silica sol and water glass composite grout into the borehole. Driven by the combined grouting pressure and capillary action, the low-viscosity grout rapidly penetrates and fills the micro-fractures along the microwave-induced thermal stress fracture network. For the directional borehole 15, a retreating segmented grouting process is also used to ensure full grouting along its entire length.

[0045] Step S4: Grout solidification and composite roof formation. Within a predetermined time, the grout undergoes a sol-gel transformation, forming a high-strength calcium silicate cement that bonds the loose and fragmented rock mass into a cohesive whole. A composite load-bearing structure, composed of rock mass and solidified grout veins, is formed in front of the tunnel boring machine's excavation face. The uniaxial compressive strength, tensile strength, and deformation modulus of this composite load-bearing structure are significantly improved compared to the original rock.

[0046] Step S5: Safe and efficient tunneling. The cutterhead 7 of the full-face tunnel boring machine (TBM) performs tunneling operations under the protection of the composite load-bearing structure, cutting the modified surrounding rock, and then carrying out subsequent permanent support construction (i.e., after the TBM passes, anchor bolts are installed on the roof of the tunnel in the completed tunneling area), completing one tunneling cycle.

[0047] The aforementioned synergistic and proactive reinforcement method addresses the problem of traditional support methods lagging behind surrounding rock deformation through the combined physical and chemical effects of microwave fracturing and chemical grouting. Microwave fracturing provides uniformly distributed permeability channels for the grout, solving the problem of difficult grouting in low-permeability rock masses; chemical grouting repairs the damage caused by microwaves and further cements the original rock, thereby enhancing the self-bearing capacity of the surrounding rock.

[0048] See attached document Figure 6 The microwave-directed fracturing and permeability enhancement subsystem, as the execution device for step S2, is used to generate thermal stress fractures within the surrounding rock mass around the borehole. The microwave-directed fracturing and permeability enhancement subsystem mainly consists of a microwave generator 4, a transmission assembly, and a waveguide assembly.

[0049] The microwave generator 4 includes a microwave source, a power switch 6, a control device 19, a circulator 5, a detector 2, and a coolant circulation device 3. The microwave source uses an industrial-grade high-power magnetron, configured to emit electromagnetic waves at frequencies of 915MHz or 2450MHz. Microwaves at 915MHz have a greater penetration depth than those at 2450MHz, and this frequency band is more suitable for on-site rock-breaking equipment. The power switch 6 connects the high-voltage power supply to the microwave source, and the control device 19 is used to adjust the output power of the microwave source and set the heating time, converting electrical energy into microwave energy output. The output power of the microwave source is configured to be 30kW or higher to meet the energy requirements for fracturing hard rock downhole.

[0050] The microwave source is connected to the waveguide assembly via a transmission component. The transmission component includes a circulator 5, configured to provide unidirectional isolation of the transmitted microwave energy. When microwave energy is reflected by rocks during transmission, generating a backwave, the circulator 5 directs this reflected wave to the coolant circulation device 3. The circulating coolant absorbs the reflected microwave energy, preventing damage to the microwave source. The detector 2 is configured to detect and adjust the incident and reflected microwave currents. The coolant circulation device 3 is also connected to the microwave generator 4 to maintain the system's thermal balance.

[0051] The waveguide assembly includes a waveguide 1 and a microwave radiation structure disposed at the front end of the waveguide 1. The waveguide 1 has a threaded interface 16 at its rear end for connection to the output end of the microwave generator 4. A microwave aperture 17 is drilled in the front wall of the waveguide 1, serving as a window for microwave energy radiation into the rock mass. The microwave aperture 17 is covered by a wave-transparent dielectric protective plate 18, which prevents water vapor and rock cuttings from flowing back into the waveguide 1 while ensuring low-loss transmission of microwave energy.

[0052] In step S2, the microwave-directed fracturing and permeation-enhancing subsystem utilizes the volumetric heating effect of microwaves and the difference in dielectric loss between rock minerals. The fissure water and clay minerals such as montmorillonite in the surrounding rock mass act as microwave-sensitive media, polarizing under microwave irradiation and absorbing electromagnetic energy, converting it into heat energy, leading to localized temperature increases and volume expansion. The control device 19 strictly controls the microwave power density acting on the rock mass within 0.5-2.0 W / cm² by adjusting the microwave source. 3 Within the specified range. Meanwhile, the control device 19 is set to maintain a single irradiation time between 30 and 120 seconds.

[0053] Under the synergistic effect of power density and time, the uneven expansion of microwave-absorbing minerals within the rock mass generates tensile thermal stress. When this tensile thermal stress exceeds the tensile strength of the rock matrix, a three-dimensional interconnected fracture network ranging from micrometers to millimeters is induced within the rock mass. This three-dimensional interconnected fracture network alters the permeability structure of the rock mass and controls the average crack aperture to be greater than the maximum particle size of the solid particles in the chemical grout injected in subsequent step S3. This provides a physical channel for the diffusion of the grout in the low-permeability rock mass, resulting in a significant improvement in the rock mass's permeability.

[0054] See attached document Figure 7The chemical grouting modification subsystem is used to inject reinforcing materials into microwave-fractured rock masses. The subsystem mainly consists of a grouting pressure pump 14, grouting pipelines, and auxiliary components. The grouting pressure pump 14 is designed as a dual-liquid grouting pressure pump with precise metering capabilities. It is equipped with a grout inlet 11, a drive motor 13, and a pressure gauge 12. The drive motor 13 provides power to the grouting pressure pump 14, and the pressure gauge 12 displays the pressure values ​​during the grouting process in real time. The grouting pressure pump 14 is connected to a storage tank for the two-component grout through the grout inlet 11, enabling the pump to draw the prepared grout material into the pump body.

[0055] The grouting pipeline includes a grouting hose 22, a connector 10, and a grouting pipe 9. The output end of the grouting pressure pump 14 is connected to the grouting hose 22 via the connector 10, and the other end of the grouting hose 22 is connected to the grouting pipe 9. The grouting pipe 9 is a tubular structure that can penetrate deep into the bottom of the borehole, and its pipe wall is provided with a grout outlet 20 for spraying grout into the borehole. A sealing device 21 is installed on the grouting pipe 9. The sealing device 21 is configured to seal the borehole opening or isolate the borehole in sections during grouting to prevent grout from flowing out of the hole or backflow, ensuring that the grout diffuses into the deeper rock mass under pressure. The system is also equipped with a two-liquid mixer, which is set in the grouting pipeline to ensure that the two components, nano-silica sol and water glass, are mixed before entering the rock mass.

[0056] The grout system delivered by the chemical grouting modification subsystem must meet specific rheological and curing properties to adapt to the microcrack network generated by microwave-induced cracking. Specifically, the initial viscosity of the mixed grout is controlled to be below 30 mPa·s. This viscosity value is close to the fluidity of water, allowing the grout to effectively penetrate and fill the microwave-induced micron to millimeter-scale cracks under the combined drive of grouting pressure and capillary action.

[0057] Furthermore, to meet the continuous operation requirements of full-face tunnel boring machines, the grouting system controls the gel time of the grout between 30 and 120 seconds by adjusting the catalyst ratio. This rapid setting characteristic ensures that the grout quickly loses its fluidity and begins to build strength after penetrating to the correct location. The solidified rock mass formed by the grout has a uniaxial compressive strength greater than 15 MPa, thereby cementing the fractured roof rock mass into a composite structure with high load-bearing capacity.

[0058] See attached document Figure 1 Appendix Figure 2 Appendix Figure 4 and attached Figure 8 Step S1: Intelligent perception and parameter decision-making of the rock mass state in front of the tunnel face is the starting point of the collaborative and proactive reinforcement operation process.

[0059] Step S1 utilizes the detection equipment integrated on the full-face tunnel boring machine to acquire geological and hydrological information of the surrounding rock ahead of the tunnel face before the cutterhead 7 begins cutting operations. Based on this information, a borehole layout plan and modification process parameters are formulated. Specifically, Step S1 uses advanced geological prediction technology to scan and detect the geological environment ahead of the tunneling axis, identifying the specific range of the advanced treatment area, the lithological type of the rock mass, the degree of joint and fracture development, the water-bearing state, and the spatial distribution of weak and fractured zones. Based on the longitudinal length of the advanced treatment area determined by the detection, the advanced geological prediction and decision-making subsystem makes logical judgments and selections between two drilling construction and reinforcement modes.

[0060] See attached document Figure 2 and attached Figure 8 When the length of the pre-treatment area confirmed by detection is relatively short, the system decides to use an onboard drilling rig to construct pre-drilling holes 23. In this mode, the operators use the onboard drilling rig deployed on the TBM drilling platform 8 to drill multiple short-distance pre-drilling holes 23 into the surrounding rock ahead. This mode is suitable for situations where the local improvement area is relatively short.

[0061] See attached document Figure 4 When the length of the pre-treatment area confirmed by detection is relatively long, the system decides to use a directional drilling rig to construct directional borehole 15. In this mode, the directional drilling rig is called to drill long-distance directional boreholes 15 along the designed outline into the deep rock mass. Through a single long-distance borehole, combined with subsequent segmented continuous modification, coverage of a large target area can be achieved.

[0062] While determining the drilling plan, the system matches key operational parameters for microwave fracturing and chemical grouting based on the detected rock physical parameters. For the microwave fracturing process, based on the content and moisture content of fissure water and sensitive minerals such as montmorillonite in the rock mass, the output power density of the microwave generator 4 is set to 0.5-2.0 W / cm³. 3 Within the specified range, the single-point irradiation time is set between 30-120 seconds. For chemical grouting technology, the system determines the grout mix ratio, grouting pressure, and grouting volume of the grouting modification subsystem based on geological information to ensure that the gel time of the grout is controlled within the range of 30-120 seconds to adapt to the tunneling rhythm.

[0063] See attached document Figure 1 Appendix Figure 2 Appendix Figure 5 Appendix Figure 6 and attached Figure 8 Step S2: Drilling and microwave intervention is the implementation phase of the physical modification operation. This step aims to establish a physical channel capable of accommodating the microwave transmission components (i.e., waveguide 1) and precisely deploy the microwave energy emission unit to the predetermined operating location deep within the rock mass.

[0064] Based on the drilling plan determined in step S1 (i.e., intelligent perception and parameter decision-making of the rock mass state ahead of the tunnel face), the operators or the automated control system control the corresponding drilling equipment to carry out the construction operation. If the onboard drilling rig construction mode is executed, the onboard drilling rig on the full-face tunnel boring machine (TBM) drilling platform 8 is controlled, the drill arm angle is adjusted, and drilling is carried out along a predetermined trajectory in the top plate area behind the cutterhead 7 or in front of the shield, forming several advance boreholes 23 into the surrounding rock. If the directional drilling rig construction mode is executed, the directional drilling rig is controlled to adjust the opening azimuth and inclination angle, and guided by the measurement-while-drilling system, to drill long-distance directional boreholes 15.

[0065] The borehole diameter (referring to the advanced borehole 23 and the directional borehole 15) is designed to match the outer diameter of the waveguide 1, and a radial gap of 5 mm to 15 mm is usually reserved to ensure that the waveguide 1 can enter and exit smoothly and to prevent rock debris from scratching and damaging the medium guard plate 18 at the front end of the waveguide 1.

[0066] After drilling to the designed depth, a hole cleaning process is immediately performed. A high-pressure air hose or high-pressure water gun is inserted into the borehole to flush and blow away any remaining drill cuttings, rock dust, and accumulated water. The cleaning operation continues until the fluid returning from the borehole opening is clear or free of obvious particles. The purpose of this process is to remove loose media adhering to the borehole wall, preventing premature heating or sparking at the borehole opening caused by highly absorbing components in the rock cuttings during the initial microwave intervention, and ensuring that the dielectric guard plate 18 on the subsequent waveguide 1 is not scratched by sharp rock cuttings.

[0067] After cleaning the borehole, the microwave intervention process begins. The waveguide 1 of the microwave-guided fracturing and permeation enhancement subsystem is disconnected from the microwave generator 4 (or its internal microwave source) (if transported separately) or kept connected via a transfer mechanism. The front end of the waveguide 1, i.e., the radiating section equipped with the microwave aperture 17 and the dielectric shield 18, is aligned with the borehole opening. With the assistance of a robotic arm or manual intervention, the waveguide 1 is smoothly pushed into the borehole.

[0068] During the drilling process, the dielectric guard plate 18 acts as a physical barrier, preventing residual mud or water droplets from the borehole wall from entering the resonant cavity inside the waveguide 1 through the microwave port 17. The waveguide 1 is continuously pushed in until its tip reaches the deepest point of the borehole or the predetermined starting irradiation position. For long-distance directional boreholes 15, the waveguide 1 uses a multi-section tube body connected by a threaded interface 16 at the tail, which is sequentially connected and extended as the drilling depth increases.

[0069] Once the waveguide 1 reaches the predetermined position at the bottom of the borehole, its axial position is fixed by a mechanical locking device, and the coolant circulation device 3 is connected to the control device 19. At this time, the microwave generator 4 is in a ready state under the control of the control device 19, and the radiation window at the microwave aperture 17 faces the area of ​​the surrounding rock to be modified at the bottom of the borehole. The system is ready to perform a retreating segmented microwave irradiation operation. This deep-to-shallow intervention strategy ensures that the deep rock mass is treated first, and as the waveguide 1 gradually retreats, the treated area will not hinder the operation in the subsequent area. It also avoids the problem that the waveguide 1 cannot penetrate deeper due to the rock mass at the borehole opening fracturing and collapsing first.

[0070] See attached document Figure 1 Appendix Figure 2 Appendix Figure 4 and attached Figure 8 Step S3: Microwave fracturing and permeability enhancement is a key process for in-situ modification of the rock mass using physical fields. This step officially begins after the waveguide 1 is positioned at the predetermined location at the bottom of the borehole. The borehole specifically includes either a pre-drilled hole 23 or a directional drilled hole 15.

[0071] First, the control device 19 sends a start command to the microwave generator 4. The microwave source (preferably a high-power magnetron with a rated power of 30kW or more and an operating frequency of 915MHz or 2450MHz) operates according to the power parameters determined in step S1 (power density 0.5-2.0W / cm³). 3 Microwaves are initiated. During this process, detector 2 detects the incident and reflected currents of the microwaves in real time and feeds the signals back to control device 19 for matching and adjustment to ensure the stability of energy output. The generated microwave energy is transmitted to the microwave aperture 17 at the front end via circulator 5, transmission components, and waveguide 1. Electromagnetic waves penetrate the medium shield 18 and radiate into the surrounding rock medium around the borehole.

[0072] During a single irradiation cycle lasting 30-120 seconds, energy conversion occurs within the surrounding rock. Fissure water and sensitive clay minerals such as montmorillonite, present in the rock mass, act as microwave absorption centers, rapidly absorbing microwave energy and converting it into heat. The microwave energy causes vaporization of water within the rock mass and differential expansion of the mineral lattice, thereby creating strong tensile thermal stress at mineral grain boundaries and fracture tips. When this thermal stress exceeds the tensile strength of the rock, primary microfractures expand and connect, actively inducing the formation of a large network of interconnected tensile thermal stress fractures ranging from micrometers to millimeters within the rock mass.

[0073] To ensure the formation of a continuous permeability-enhancing zone in the rock mass along the borehole axis, this step employs a retreating segmented irradiation process. The specific operational logic is as follows: After completing a single irradiation at the current location, the control device 19 temporarily shuts off the microwave source or sets it to standby mode. Subsequently, the waveguide 1 is driven back a predetermined distance along the borehole axis towards the borehole opening via a transport mechanism. To prevent the formation of unfractured areas between adjacent irradiated zones, this retreat distance is set to be less than the effective axial radiation length formed by the microwave borehole 17 in the rock mass. This ensures that the heating zones of two adjacent irradiations partially overlap longitudinally, guaranteeing the continuous continuity of the fracture network throughout the entire target area.

[0074] The system repeatedly executes the cycle of irradiation, stop, retreat, and irradiation until waveguide 1 retreats to a safe distance from the borehole opening or covers the entire advanced treatment area.

[0075] During microwave fracturing, the rock mass undergoes thermal disintegration due to heat, and some rock fragments detach and fall into the borehole. Therefore, after the microwave operation is completed and the waveguide 1 is completely withdrawn from the borehole, a secondary cleaning procedure is immediately performed. Personnel or automated machinery use pneumatic cleaning devices (such as high-pressure air nozzles) or washing devices to extend into the borehole and clean the rock cuttings within the borehole and fractures. The technical purpose of this secondary cleaning step is to: remove large rock fragments generated by thermal disintegration to prevent them from obstructing the subsequent lowering of the grouting pipe 9; and use fluid pressure (such as air pressure) to clear the openings of the newly formed fractures induced by microwaves, remove accumulated dust, and ensure that the chemical grout in the subsequent step S4 can smoothly enter the deep fracture network.

[0076] See attached document Figure 1 Appendix Figure 3 Appendix Figure 5 and attached Figure 7 Step S4: Chemical grouting and bonding. This step follows immediately after step S3, utilizing the physical channels created by microwave fracturing to achieve high-pressure permeation grouting after microwave modification.

[0077] The operators insert the grouting pipe 9 of the chemical grouting modification subsystem into the borehole (including the advanced borehole 23 or the directional borehole 15) after secondary cleaning. For the advanced borehole 23 constructed by the air-mounted drilling rig, the grouting pipe 9 is inserted to the bottom of the hole in one go; for the directional borehole 15 constructed by the directional drilling rig, a segmented retreating grouting process is adopted, in which the grouting pipe 9 is first inserted to the deepest grouting section at the bottom of the hole.

[0078] After the grouting pipe 9 reaches the predetermined position, the sealing device 21 is operated by hydraulic or mechanical means. The sealing device 21 expands radially and fits tightly against the inner wall of the borehole, forming a closed grouting cavity. The closed grouting cavity ensures that the subsequently injected grout will not flow back and leak along the borehole axis, but will be forced to diffuse into the surrounding rock fissures.

[0079] Immediately, the grouting pressure pump 14 is started. The two independent pump cylinders of the grouting pressure pump 14 draw component A (nano-silica sol) and component B (modified water glass and catalyst) from the storage tank, respectively. The two fluid components enter the delivery pipeline under pressure and converge in a two-liquid mixer located at the front end of the grouting pipe 9 or within the pipeline. The mixing structure inside the two-liquid mixer forces the two fluids to undergo intense turbulent mixing, ensuring a homogeneous mixed slurry is formed before exiting the slurry outlet 20.

[0080] The mixed grout enters the closed section of the borehole through the outlet 20 of the grouting pipe 9. At this point, due to the microwave irradiation in step S3 inducing a connected microfracture network within the rock mass, and according to the grout system design, the initial viscosity of the mixed grout is controlled to be below 30 mPa·s (close to water). Driven by both the grouting pressure and the capillary action of the fractures, the grout can quickly overcome the seepage resistance and effectively penetrate and uniformly diffuse into the deep microfracture network of the rock mass surrounding the borehole. This penetration method avoids excessive damage to the surrounding rock caused by traditional single high-pressure fracturing grouting and achieves full-area filling of the fracture network.

[0081] When the grouting pressure reaches the preset cutoff pressure or the grouting volume reaches the theoretical calculation value, the grouting of the current section is stopped. For directional borehole 15, the sealing device 21 is operated to contract and unseal, the grouting pipe 9 is moved back one step, and the sealing device 21 is expanded again to carry out the next section of grouting until the grouting of the entire hole is completed.

[0082] Under the action of a catalyst, the grout injected into the rock fissures undergoes a sol-gel reaction within a predetermined gelation time (30-120 s). Nano-silica sol and water glass components chemically polymerize to form a silica-calcium cement with a three-dimensional network structure and a compressive strength greater than 15 MPa. This cement not only fills the microwave-induced micro-fractures and primary pores but also re-cements loose rock particles into a cohesive whole, thus forming a composite artificial and natural roof structure of a certain thickness in front of the tunneling face. The formation of this composite structure marks the completion of the advanced modification operation, creating conditions for the safe tunneling of the subsequent TBM.

[0083] See attached document Figure 1 Appendix Figure 2 Appendix Figure 4 Appendix 8, Step S5: Composite roof formation and TBM tunneling are the final steps in the collaborative advanced active reinforcement process.

[0084] After grouting is completed in step S4 and the grout reaches the predetermined gel time (30-120s), the grout injected into the rock mass undergoes a sol-gel transition and completely solidifies. At this time, in the top plate area in front of the cutterhead 7, the silica-calcium cement formed by the nano-silica sol and water glass components firmly bonds the rock mass on both sides of the fractures generated by microwave fracturing. The original rock matrix, the microwave-induced fracture network, and the high-strength consolidated body filling the fractures together constitute a highly integrated artificial and natural composite load-bearing arch.

[0085] After processing using the method described in this embodiment, the roof of the target area is transformed from loose and fractured rock mass into a magma composite material, resulting in a fundamental improvement in its mechanical properties. Specifically, the average cohesion (c-value) of the reinforced roof rock mass can be increased by 50%-150%, and the average internal friction angle ( The uniaxial compressive strength of the solidified slurry is greater than 15 MPa, which significantly increases the uniaxial compressive strength, tensile strength and deformation modulus of the composite roof, enabling it to resist high ground stress and mining effects.

[0086] After the composite roof is formed, a full-face tunnel boring machine (TBM) performs tunneling operations. The cutterhead 7 cuts the rock under the actively reinforced artificial and natural composite load-bearing arch. Because the self-supporting capacity of the roof rock mass has been fundamentally enhanced through the synergistic effect of microwave fracturing and chemical grouting, the initial roof collapse and high-risk areas at the working face are effectively prevented. The composite roof maintains its integrity as it is cut and moves forward with the shield, thus achieving safe, efficient, and high-quality tunneling. After the TBM passes, workers carry out permanent support construction, such as installing anchor bolts, in the safe area behind the completed tunneling area, completing a full construction cycle.

[0087] When the TBM advances to the effective coverage length of the advanced treatment area determined in step S1, the system determines that the current reinforcement cycle has ended, re-enters step S1, and begins the next cycle of advanced detection and reinforcement work until it passes through the unfavorable geological section.

[0088] In this embodiment, the artificial and natural composite roof support structure is formed based on the synergistic mechanism of microwave-induced thermal stress cracking and chemical grout penetration bonding.

[0089] Specifically, the microwave-directed fracturing and permeability enhancement subsystem utilizes the selective volumetric heating effect of microwave fields on fissure water and sensitive clay minerals (such as montmorillonite) in the surrounding rock to establish a transient non-uniform temperature field inside the rock mass.

[0090] During construction, a directional drilling rig is first used to create a directional borehole 15 within the surrounding rock. Then, a waveguide 1 is inserted into the directional borehole 15. Microwave energy is emitted through a microwave aperture 17 at the tip of the waveguide 1. Due to the difference in dielectric loss between the rock matrix and the water-bearing minerals, the microwave energy is selectively absorbed and converted into heat energy, causing vaporization of water within the rock mass and differential expansion of the mineral lattice. This uneven thermal expansion, within a short time (30-120 seconds), builds tensile thermal stress exceeding the tensile strength of the rock at the mineral grain boundaries and fracture tips. When this thermal stress exceeds the tensile strength of the surrounding rock, the primary microfractures expand and connect, inducing the generation of a large number of interconnected tensile thermal stress fracture networks ranging from micrometers to millimeters in size. This process significantly increases the permeability coefficient of the rock mass, creating the necessary seepage channels for subsequent grout injection.

[0091] Subsequently, the chemical grouting subsystem utilizes the highly permeable fracture network formed by the aforementioned microwave fracturing to inject a low-viscosity (<30 mPa·s) nano-silica sol and water glass composite grout into the surrounding rock.

[0092] At this point, the waveguide 1 is withdrawn from the directional borehole 15, and the grouting pipe 9 is inserted into the same directional borehole 15. Because the surface of the fractures generated by microwave fracturing is dry and has high roughness, the mechanical interlocking force between the grout and the rock interface is significantly enhanced. Driven by both the grouting pressure provided by the grouting pressure pump 14 and capillary action, the grout flows out through the outlet 20 of the grouting pipe 9, rapidly filling the microwave-induced secondary fractures and the original micropores of the rock. Within a predetermined gelation time, the grout undergoes a sol-gel reaction, solidifying to form a silica-calcium cement with a compressive strength greater than 15 MPa.

[0093] To further verify the authenticity of the above-mentioned formation mechanism and technical effects, this embodiment selected a typical coal mine roadway roof lithology rich in clay minerals: silty mudstone, for comparative testing. The experimental group was treated using the method of this invention: firstly, the microwave power density was set to 1.5 W / cm² using microwave generator 4. 3 The rock samples were subjected to directional irradiation for 90 seconds. Subsequently, a composite grout of nano-silica sol and water glass with an initial viscosity of 20 mPa·s was injected using a grouting pressure pump 14, with the grouting pressure controlled at 2.0 MPa, and the samples were allowed to solidify. The control group consisted of untreated homogeneous natural rock samples.

[0094] The shear strength parameters of two groups of rock samples were determined by triaxial compression tests. The results showed that:

[0095] Control group (natural rock sample): average cohesion (c value) was 1.8 MPa, average internal friction angle ( The value is 28.0°.

[0096] Experimental group (treated rock samples): average cohesion (c value) increased to 4.1 MPa, average internal friction angle ( The value was increased to 31.0°.

[0097] Calculations showed that the cohesion of the treated rock mass increased by approximately 127%, and the internal friction angle increased by approximately 10.7%. These experimental data fully validate that, after treatment using this method, the average cohesion (c-value) of the roof rock mass can be increased by 50%-150%, and the average internal friction angle (c-value) can be increased by approximately 10.7%. The value can improve the technical effect by 5%-15%. This indicates that through the synergistic effect of microwave and chemical grouting, loose and broken surrounding rock particles are re-cemented into a whole, and macroscopically transformed into an artificial and natural composite roof bearing structure with high load-bearing capacity.

Claims

1. A collaborative proactive reinforcement method for TBM tunneling, characterized in that, Includes the following steps: Geological information of the surrounding rock in front of the tunnel face is obtained by using the detection equipment integrated on the full-face tunnel boring machine. Based on the geological information, a drilling layout plan and modification process parameters are formulated, and drilling is carried out to form boreholes. The boreholes are either advance boreholes (23) or directional boreholes (15). After the drilling is completed, the waveguide (1) is inserted into the borehole, and the microwave generator (4) is started to radiate microwave energy to the surrounding rock around the borehole, inducing the formation of a fracture network inside the surrounding rock. After the operation is completed, the inside of the borehole is cleaned. Insert the grouting pipe (9) into the cleaned borehole, seal it with the sealing device (21), start the grouting pressure pump (14), and pressurize the chemical grout into the borehole; The chemical slurry solidifies within a predetermined time to form a composite load-bearing structure of artificial and natural roof slabs; wherein, the chemical slurry is a composite slurry of nano-silica sol and water glass, the initial viscosity of the chemical slurry is less than 30 mPa·s, the predetermined time is 30-120 s, and the chemical slurry solidifies to form a silica-calcium cement with a three-dimensional network structure and a compressive strength greater than 15 MPa. The cutterhead (7) of the full-face tunnel boring machine performs tunneling operations under the protection of the artificial and natural composite roof bearing structure; The drilling layout scheme specifically includes: Based on the geological information, the longitudinal length of the advanced treatment area is determined. If the longitudinal length is less than a preset length threshold, it is considered the first case. If the longitudinal length is greater than or equal to the preset length threshold, it is considered the second case. The preset length threshold is 10m. When the first situation is determined, the advanced borehole (23) is constructed using the onboard drilling rig of the full-face tunnel boring machine; when the second situation is determined, the directional borehole (15) is constructed using a directional drilling rig. The airborne drilling rig is arranged on the drilling platform (8) of the full-face tunnel boring machine. The microwave generator (4) is equipped with a microwave source, which is connected to a power switch (6). The power switch (6) is used to connect the power source to the microwave source. The microwave source is connected to a control device (19), which is used to adjust the output power of the microwave source. A circulator (5) is provided on the output path of the microwave source. The circulator (5) is used to unidirectionally isolate the transmitted microwave energy and guide the reflected wave to the coolant circulation device (3). A detector (2) is provided in the circuit of the microwave generator (4). The detector (2) is used to detect the incident current and reflected current of the microwave. The control device (19) sets the output power density of the microwave source to 0.5-2.0 W / cm². 3 The single irradiation time is set to 30-120s, and the output power of the microwave source is 30kW or higher. For the directional borehole (15), the waveguide (1) moves from the bottom of the borehole to the opening of the borehole within the directional borehole (15) and radiates the microwave energy in a backward segmented manner; The microwave source is used to emit electromagnetic waves with a frequency of 915MHz. The microwave energy is used to vaporize the water inside the surrounding rock and cause the mineral lattice to expand, thereby creating tensile thermal stress at the mineral grain boundaries and crack tips of the surrounding rock. The waveguide (1) is provided with a threaded interface (16) at its tail end. The threaded interface (16) is used to connect to the output end of the microwave generator (4). A microwave hole (17) is drilled on the front wall of the waveguide (1). The microwave hole (17) is used to emit microwave energy outward. The outside of the microwave hole (17) is covered with a dielectric protective plate (18). The dielectric protective plate (18) is used to prevent water vapor and rock debris from entering the interior of the waveguide (1) and to allow the microwave energy to penetrate.

2. The collaborative advanced active reinforcement method for TBM tunneling according to claim 1, characterized in that, The sealing device (21) is installed on the grouting pipe (9). The sealing device (21) is used to seal the opening of the borehole and to isolate the borehole in sections. For the directional borehole (15), the sealing device (21) and the grouting pipe (9) move from the bottom of the borehole to the opening of the borehole within the directional borehole (15), and the chemical grout is injected into the directional borehole (15) in a backward segmented manner.

3. The collaborative advanced active reinforcement method for TBM tunneling according to claim 1, characterized in that, The grouting pressure pump (14) is connected to a drive motor (13), which provides power to the grouting pressure pump (14). The grouting pressure pump (14) is also equipped with a grout inlet (11) and a pressure gauge (12). The output end of the grouting pressure pump (14) is connected to one end of the grouting hose (22) through a connector (10). The other end of the grouting hose (22) is connected to the grouting pipe (9). The grouting pipe (9) has a grout outlet (20) on its wall.

4. The collaborative advanced active reinforcement method for TBM tunneling according to claim 1, characterized in that, The borehole interior and fracture network are cleaned using a fluid selected from high-pressure air or water. The cutterhead (7) of the full-face tunnel boring machine cuts the modified surrounding rock and performs permanent support construction after passing through.

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