Anti-clogging foam injection system and method for shield construction

Abstract

This invention discloses an anti-clogging foam spraying system and method for tunnel boring machine (TBM) construction, relating to the field of TBM construction technology. Traditional methods involve setting up a foam supply unit and spraying modules, with foam spray nozzles often located on the inner wall of the soil chamber or the back of the cutterhead. This forces the foam to travel a relatively long path through the soil chamber or cutterhead to reach the working face, resulting in significant foam collapse during transport and difficulty in effectively improving the core area of ​​the working face at the front of the cutterhead. This leads to soil accumulation and compaction in front of the cutterhead, abnormal cutter wear, and the risk of clogging. This embodiment, by directly installing the spraying module on the front of the cutterhead and positioning the foam spraying end directly towards the working face, fundamentally shortens the foam's action path, ensuring that the foam acts directly on the area most in need of improvement with the highest activity and optimal concentration.

Description

Technical Field

[0001] This invention relates to the field of tunnel boring machine (TBM) construction technology, and in particular to an anti-clogging foam spraying system and method for TBM construction. Background Technology

[0002] Shield tunneling is one of the most widely used construction methods in urban underground engineering and long-distance tunnel construction. With the continuous development of shield tunneling technology, foam injection technology has been gradually introduced into shield tunneling and widely applied to improve the fluidity of the cutterhead cutting the soil, reduce cutter wear, and prevent the accumulation and compaction of excavated soil in the cutterhead and soil chamber. Foam injection technology injects foam into the tunnel face and soil chamber area to maintain the excavated soil in a good fluid plastic state, thereby effectively improving shield tunneling efficiency and construction safety.

[0003] Currently, the foam spraying system of tunnel boring machines typically consists of a foam generator, delivery pipelines, and spray nozzles located at the cutterhead or soil chamber. During construction, the foam concentrate is mixed with compressed air by the foam generator to produce foam, which is then transported through pipelines to the spray nozzles and injected into the cutterhead area or soil chamber to improve the soil at the tunnel face.

[0004] However, the injection nozzles of existing systems are mostly located on the inner wall of the soil chamber or the back of the cutterhead, making it difficult for the foam to act directly and promptly on the face in front of the cutterhead. This results in limited soil improvement at the face, and soil accumulation, compaction, and blockage are still prone to occur in the area in front of the cutterhead. Summary of the Invention

[0005] The main objective of this invention is to propose an anti-clogging foam spraying system and method for shield tunneling construction. This aims to solve the technical problem that in existing systems, the spray nozzles are mostly located on the inner wall of the soil chamber or the back of the cutterhead, making it difficult for the foam to act directly and promptly on the face in front of the cutterhead. This results in limited soil improvement at the face and the area in front of the cutterhead is still prone to soil accumulation, compaction, and clogging.

[0006] To achieve the above objectives, in a first aspect, the present invention provides an anti-clogging foam spraying system for tunnel boring machine (TBM) construction, comprising: A foam supply unit, wherein the foam supply unit stores foam concentrate; and, The spraying module is installed on the cutterhead of the tunnel boring machine. The foam spraying end of the spraying module is positioned facing the working face in front of the cutterhead. The spraying module is connected to the foam supply unit through a pipeline. A control valve is installed on the pipeline. The control valve can switch between an open state and a closed state, which opens the pipeline and sprays the foam concentrate toward the working face.

[0007] In one embodiment, the spraying module includes: A cylinder, one end of which is bolted to the cutterhead of the tunnel boring machine, an installation space is formed inside the cylinder, the cylinder extends from the cutterhead toward the working face in front of the cutterhead, and a liquid inlet communicating with the installation space is formed at the end of the cylinder near the cutterhead. A foam forming mechanism is installed at the end of the installation space away from the cutter head. A foam ejection space is formed within the foam forming mechanism. The foam forming mechanism can process foam concentrate entering the installation space through the inlet into foam and inject it into the foam ejection space. The end of the foam forming mechanism away from the cylinder forms a foam ejection end. A foam ejection mechanism is installed at the foam ejection end, and the foam ejection space can eject the foam formed and injected by the foam forming mechanism from the foam ejection mechanism toward the working face.

[0008] In one embodiment, the foam forming mechanism includes: A first connecting cylinder, one end of which engages with the end of the cylinder body away from the cutter head, and a first bubble-forming hole is formed at the end of the first connecting cylinder away from the mounting space; and... The second connecting tube is installed at the end of the first connecting tube away from the cylinder body. The foam ejection space is formed between the second connecting tube and the first firing hole of the first connecting tube. The cylinder body, the first connecting tube and the second connecting tube extend in the same direction.

[0009] In one embodiment, the end of the first connecting cylinder away from the cylinder body protrudes toward the end away from the cylinder body and forms a spherical protrusion, and the first bubble-forming hole is formed on the spherical protrusion; There are multiple first bubble-forming holes, and the array of multiple first bubble-forming holes is distributed on the spherical protrusion.

[0010] In one embodiment, a first groove is formed at the end of the cylinder away from the cutter head, and a second groove and a first engaging protrusion are respectively formed on the outer walls of both ends of the first connecting cylinder along its length direction, wherein the first engaging protrusion is sealed and engaged with the first groove. A second snap-fit ​​protrusion is formed on the inner wall of one end of the second connecting cylinder, and the second snap-fit ​​protrusion is sealed and engaged with the second slot.

[0011] In one embodiment, the foam ejection mechanism includes: A foam extrusion disc is installed at the end of the second connecting cylinder away from the first connecting cylinder. The foam extrusion disc has a plurality of second bubble-forming holes arranged in an array, and the second bubble-forming holes are in communication with the foam ejection space. A foam ejection disc is installed at the end of the foam extrusion disc away from the second connecting cylinder. Multiple baffle plates are installed on the foam ejection disc, and these baffle plates are spaced apart circumferentially and surround to form an ejection valve. The ejection valve is tapered away from the foam extrusion disc along the extending direction of the cylinder. A fixed plate is installed at the end of the foam ejection plate away from the foam extrusion plate, and the foam on the base of the foam extrusion plate can open the ejection valve and be ejected toward the working face.

[0012] In one embodiment, the cylindrical body includes; A third connecting cylinder, wherein the mounting space is formed within the third connecting cylinder, one end of the third connecting cylinder forms the first retaining groove, and the end of the third connecting cylinder away from the first retaining groove forms a liquid inlet; and... A connecting plate is installed at the end of the third connecting cylinder away from the first slot, and the first connecting plate is connected to the cutter head.

[0013] In one embodiment, the third connecting cylinder is further provided with a plurality of spheres, the diameter of which is larger than the diameter of the liquid inlet and the first bubble-forming hole.

[0014] Based on the same technical concept, in a second aspect, the present invention also proposes a method for spraying anti-clogging foam for tunnel boring machine (TBM) construction, using the anti-clogging foam spraying method for TBM construction described in the first aspect, wherein the spraying method includes the following steps: The spraying module is used to prepare the foam concentrate supplied through the pipeline into foam to be sprayed. The foam to be sprayed is sprayed toward the working face.

[0015] In one embodiment, prior to the step of spraying the foam to be sprayed toward the working face, the method further includes: Multiple steel balls are arranged inside the spray module; The foam concentrate entering the spraying module is controlled to drive the movement of the steel balls so that the foam is sprayed out in one direction toward the working face.

[0016] The technical solution of this invention, by setting up a foam supply unit and a spraying module, addresses the issue that in traditional methods, foam spray nozzles are often located on the inner wall of the soil chamber or the back of the cutterhead. This forces the foam to travel a long path through the soil chamber or cutterhead to reach the working face, resulting in significant foam collapse during transport and hindering effective improvement of the core area at the front of the cutterhead. This leads to soil accumulation and compaction in front of the cutterhead, abnormal cutter wear, and the risk of blockage. This embodiment, by directly installing the spraying module on the front of the cutterhead and positioning the foam spraying end directly towards the working face, fundamentally shortens the foam's action path, ensuring that the foam acts directly on the area most in need of improvement with maximum activity and optimal concentration. Through this structure, the fluidity of the soil at the working face is controlled in real-time and precisely, the cutterhead cutting resistance is significantly reduced, and the cutter wear rate is reduced by approximately 35%-45% compared to existing technologies. Simultaneously, it avoids soil compaction and blockage at the cutterhead spokes and openings, effectively improving the continuous tunneling efficiency and construction safety of the tunnel boring machine. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0018] Figure 1 A schematic diagram of the anti-clogging foam spraying system for tunnel boring machine construction provided by the present invention; Figure 2 for Figure 1 The example spray module is shown in the schematic diagram. Figure 3 for Figure 2 A schematic diagram of the structure in the explosive state; Figure 4 for Figure 3 The diagram shows the structure of the foam molding mechanism in the explosion state as shown in the example. Figure 5 for Figure 4 A schematic diagram of the internal structure of the example structure; Figure 6 for Figure 2 A side view of the structure shown in the example; Figure 7 This is a flowchart illustrating an anti-clogging foam spraying method for tunnel boring machine (TBM) construction, as an example of the present invention.

[0019] Figure label: 10. Foam supply unit; 20. Spraying module; 30. Control valve; 100. Cylinder; 110. Installation space; 120. Liquid inlet; 200. Foam forming mechanism; 210. Foam spraying space; 300. Foam spraying mechanism; 220. First connecting cylinder; 230. First bubble-forming hole; 240. Second connecting cylinder; 250. First slot; 260. Second slot; 270. First locking protrusion; 280. Second locking protrusion; 310. Foam extrusion disc; 320. Second bubble-forming hole; 330. Foam spraying disc; 340. Baffle plate; 350. Fixing disc; 130. Third connecting cylinder; 140. Connecting plate.

[0020] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0022] It should be noted that if the embodiments of the present invention involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a specific posture. If the specific posture changes, the directional indicators will also change accordingly.

[0023] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the use of "and / or" or "and / or" throughout the text includes three parallel solutions. For example, "A and / or B" includes solution A, solution B, or a solution where both A and B are satisfied simultaneously. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0024] This invention proposes an anti-clogging foam spraying system and method for tunnel boring machine (TBM) construction.

[0025] Please see Figure 1For ease of understanding, this anti-clogging foam spraying system for tunnel boring machine (TBM) construction includes: Foam supply unit 10, which stores foam concentrate; and, The spraying module 20 is installed on the cutterhead of the tunnel boring machine. The foam spraying end of the spraying module 20 is set facing the working face in front of the cutterhead. The spraying module 20 is connected to the foam supply unit 10 through a pipeline. A control valve 30 is installed on the pipeline. The control valve 30 can switch between an open state and a closed state, which opens the pipeline and sprays foam concentrate towards the working face.

[0026] Specifically, the foam supply unit 10 uses a storage tank with constant pressure output function, which stores foam concentrate pre-mixed to a set concentration. The spraying module 20 is fixedly installed on the front area of ​​the tunnel boring machine cutterhead via a high-strength connecting support. Its foam spraying end is equipped with multiple nozzles arranged in a matrix, with the axis of all nozzles facing the face directly in front of the cutterhead. The distance between the nozzle outlet and the face is controlled within the range of 300mm to 800mm, so that the foam can act directly on the excavation face with the shortest path. The spraying module 20 is connected to the foam supply unit 10 through a pressure-resistant pipeline. The pipeline is laid along the central rotary joint of the cutterhead and inside the main shaft of the tunnel boring machine. A control valve 30 is installed in series on the pipeline. The control valve 30 is an electromagnetically driven structure that can quickly switch between an open state (opening the pipeline and spraying foam concentrate towards the face) and a closed state (completely cutting off the pipeline) after receiving a command from the control system.

[0027] During construction, when the tunnel boring machine (TBM) reaches a stratum requiring soil improvement, the control system sends an opening command to control valve 30. Control valve 30 then switches to the open state, and the foam concentrate, driven by pressure from the supply unit, is stably delivered along the pipeline to the spraying module 20. It is then sprayed at high speed from multiple nozzles in a fan-shaped atomization pattern. Because the spraying end directly faces the tunnel face, the foam immediately comes into full contact with the soil upon leaving the nozzle, penetrating the soil pores in a very short time. This forms a lubricating film on the surface of soil particles, significantly reducing the internal friction angle and cohesion of the soil, thereby transforming the originally plastic or stiff plastic soil into improved slag with good flowability. This improved slag is easily flowable under the cutting action of the cutterhead, smoothly entering the soil chamber through the cutterhead opening, avoiding the compaction phenomenon caused by compression and frictional heat in front of the cutterhead.

[0028] In existing technologies, foam injection nozzles are mostly located on the inner wall of the soil chamber or the back of the cutterhead. The foam must travel a relatively long path through the soil chamber or cutterhead to reach the working face, resulting in significant foam collapse during transport. Furthermore, it is difficult to effectively improve the core area of ​​the working face at the very front of the cutterhead, leading to soil accumulation and compaction in front of the cutterhead, abnormal cutter wear, and the risk of blockage. This embodiment, by directly installing the injection module 20 on the front of the cutterhead and positioning the foam injection end directly towards the working face, fundamentally shortens the foam's action path, ensuring that the foam acts directly on the area most in need of improvement with the highest activity and optimal concentration. Through the implementation of this structure, the fluidity of the soil at the working face is controlled in real time and with precision, the cutterhead cutting resistance is significantly reduced, and the cutter wear rate is reduced by approximately 35%-45% compared to existing technologies. Simultaneously, it avoids soil compaction and blockage at the cutterhead spokes and openings, effectively improving the continuous tunneling efficiency and construction safety of the tunnel boring machine.

[0029] In one embodiment, the spraying module 20 includes: The cylinder 100 has one end bolted to the cutterhead of the tunnel boring machine. An installation space 110 is formed inside the cylinder 100. The cylinder 100 extends from the cutterhead toward the working face in front of the cutterhead. A liquid inlet 120 communicating with the installation space 110 is formed at the end of the cylinder 100 near the cutterhead. A foam forming mechanism 200 is installed at the end of the installation space 110 away from the cutter head. A foam ejection space 210 is formed within the foam forming mechanism 200. The foam forming mechanism 200 can form foam from the foam concentrate entering the installation space 110 through the inlet 120 and inject it into the foam ejection space 210. The end of the foam forming mechanism 200 away from the cylinder 100 forms a foam ejection end; and... The foam ejection mechanism 300 is installed at the foam ejection end. The foam ejection space 210 can eject the foam formed and injected by the foam forming mechanism 200 from the foam ejection mechanism 300 toward the working face.

[0030] Specifically, the spraying module 20 includes a cylinder 100, a foam forming mechanism 200, and a foam spraying mechanism 300. One end of the cylinder 100 is fixedly connected to the front of the cutterhead of the tunnel boring machine by bolts. An axially extending installation space 110 is formed inside the cylinder 100. The cylinder 100 extends a certain length from the cutterhead toward the working face in front of the cutterhead, so that the end away from the cutterhead is closer to the working face. A liquid inlet 120 communicating with the installation space 110 is formed at the end of the cylinder 100 near the cutterhead. The liquid inlet 120 is connected to the foam supply unit 10 through a pipeline. The foam forming mechanism 200 is installed at the end of the installation space 110 away from the cutter head. A foam ejection space 210 is formed within the foam forming mechanism 200. The foam forming mechanism 200 can mix the foam concentrate entering the installation space 110 through the inlet 120 with compressed air to form foam, which is then injected into the foam ejection space 210. The end of the foam forming mechanism 200 away from the cylinder 100 forms a foam ejection end. The foam ejection mechanism 300 is installed at the foam ejection end. The foam ejection space 210 can atomize and eject the foam formed and injected by the foam forming mechanism 200 towards the working face.

[0031] In this embodiment, the spraying module 20 is installed on the front of the cutter head. After the control valve is opened, the foam concentrate enters the inlet 120 of the cylinder 100 from the foam supply unit 10 through the pipeline, and then flows away from the cutter head along the installation space 110. When the foam concentrate reaches the foam forming mechanism 200 installed at the front end of the installation space 110, the mixing chamber inside the mechanism performs high-speed shearing and mixing of the foam concentrate with the synchronously introduced compressed air to form stable and fine foam, which is then pushed into the foam ejection space 210. Subsequently, the foam ejection mechanism 300 sprays these freshly generated foam directly onto the working face in a fan-shaped diffusion form through its multiple honeycomb-arranged nozzles. Since the cylinder 100 extends the foam forming mechanism 200 to the front of the cutter head near the working face, the path of the foam from generation to ejection is greatly shortened, avoiding the large-scale collapse phenomenon caused by the long-distance pipeline transportation of foam in the prior art. In this embodiment, the foam is generated on-site and immediately sprayed near the tunnel face. It penetrates directly into the soil pores at the tunnel face with maximum liquid content and optimal surface activity, rapidly reducing internal friction and cohesion. This keeps the cut soil in a good fluid state, allowing it to smoothly enter the soil chamber through the cutterhead opening. This process effectively solves the problem of soil accumulation, compaction, and blockage caused by the foam's inability to directly act on the tunnel face due to the injection nozzle being located on the inner wall of the soil chamber or the back of the cutterhead in existing technologies. It significantly reduces the fluctuation range of cutterhead torque, improving the tunneling efficiency and construction continuity of the tunnel boring machine.

[0032] In one embodiment, the foam forming mechanism 200 includes: A first connecting cylinder 220, one end of which engages with the end of the cylinder body 100 away from the cutter head, and a first bubble-forming hole 230 is formed at the end of the first connecting cylinder 220 away from the mounting space 110; and, The second connecting cylinder 240 is installed at the end of the first connecting cylinder 220 away from the cylinder body 100. A foam ejection space 210 is formed between the second connecting cylinder 240 and the first firing hole of the first connecting cylinder 220. The cylinder body 100, the first connecting cylinder 220 and the second connecting cylinder 240 extend in the same direction.

[0033] Specifically, the cylinder 100 of the spray module 20 is bolted to the front of the cutter head. The foam concentrate, after being opened by the control valve, enters the installation space 110 through the inlet 120 near the cutter head end of the cylinder 100 and is transported forward axially along the cylinder 100. When the foam concentrate reaches the end of the cylinder 100 furthest from the cutter head, it sequentially enters the first connecting cylinder 220, which is engaged with the cylinder 100, and then enters the foam ejection space 210 formed by the first connecting cylinder 220 and the second connecting cylinder 240 through the first bubble-forming hole 230 formed at the end of the first connecting cylinder 220. During this process, compressed air simultaneously enters the foam ejection space 210 through the air inlet channel located on the side wall of the first connecting cylinder 220, and undergoes intense turbulent mixing with the foam concentrate ejected through the first bubble-forming hole 230, completing the on-site generation of foam. The generated foam is further stabilized in the foam ejection space 210, and then directly sprayed into the face in front of the cutter head by the foam ejection mechanism 300 installed at the front end of the second connecting cylinder 240 in a high-pressure atomized form.

[0034] Because the cylinder 100, the first connecting cylinder 220, and the second connecting cylinder 240 are arranged in a coaxial extension manner, the foam generation position is significantly moved forward to a region closer to the tunnel face, greatly shortening the time and spatial distance from foam generation to its application to the soil. In the prior art, foam is usually pre-prepared in the generation device at the rear of the tunnel boring machine and then transported to the injection port on the back of the cutterhead or the inner wall of the soil chamber via long-distance pipelines. During this process, a large amount of foam breaks down and it is difficult to effectively improve the core area of ​​the tunnel face. In this embodiment, by engaging the first connecting cylinder 220 with the cylinder 100 and sequentially assembling the second connecting cylinder 240 with the first connecting cylinder 220, the foam mixing and generation stage is directly set in front of the cutterhead, realizing on-site mixing and spraying of foam. This ensures that the foam penetrates directly into the pores of the tunnel face soil in its most active state, rapidly improving the fluidity and plasticity of the soil. This effectively prevents the soil from hardening and clogging in front of the cutterhead due to compression and friction, reduces the peak torque of the cutterhead, reduces abnormal wear of the cutters, and improves the continuity and efficiency of tunnel boring.

[0035] In one embodiment, the end of the first connecting cylinder 220 away from the cylinder body 100 protrudes toward the end away from the cylinder body 100 and forms a spherical protrusion, and a first bubble-forming hole 230 is formed on the spherical protrusion; There are multiple first bubble-forming holes 230, and the array of multiple first bubble-forming holes 230 is distributed on the spherical protrusion.

[0036] Specifically, the cylinder 100 of the spraying module 20 is bolted to the front of the tunnel boring machine cutterhead. Its installation space 110 is connected to the foam supply unit 10 via a pipeline, and a control valve controls the flow of foam concentrate. The first connecting cylinder 220 is fitted to the end of the cylinder 100 away from the cutterhead by a snap-fit ​​mechanism, and the second connecting cylinder 240 is installed at the end of the first connecting cylinder 220 away from the cylinder 100. All three extend in the same direction, so that the foam spraying space 210 is formed between the first foam-forming hole 230 and the second connecting cylinder 240. When the control valve is switched to the open state, the foam concentrate enters the installation space 110 of the cylinder 100 from the inlet 120 and is transported forward. When it reaches the end of the first connecting cylinder 220, it is sprayed out sequentially through multiple first foam-forming holes 230 arranged in an array on a spherical protrusion. The spherical protrusions create a spatially curved distribution of the outlet positions of the foam-forming holes. The foam concentrate is ejected from multiple orifices at different minute angles, forming multi-point turbulent shear mixing with the synchronously introduced compressed air within the foam ejection space 210, generating microfoam with uniform particle size and high stability. Subsequently, these foams are directly sprayed in an atomized form onto the face of the cutter head via the foam ejection mechanism 300 at the front end of the second connecting cylinder 240.

[0037] Because the spherical protrusions increase the surface area of ​​the first foam-generating holes 230, and the multiple foam-generating holes are arranged in an array, the foam concentrate can be evenly dispersed into the foam ejection space 210 in the form of multiple fine streams, avoiding the localized uneven mixing phenomenon that easily occurs when injecting at a single point. In the prior art, the foam injection port is mostly located on the inner wall of the soil chamber or the back of the cutterhead, and the foam needs to travel a long path to reach the working face, resulting in a high failure rate and delayed action. In this embodiment, the spherical protrusion structure of the first connecting cylinder 220 further advances the foam-generating position and optimizes the fluid outlet shape, so that the foam immediately covers a large area of ​​the working face in the best active state after generation, quickly penetrates into the soil pores and forms a continuous liquid film, effectively reducing the internal friction angle and cohesion of the soil. As a result, the soil at the working face is transformed into a fluid plastic state in real time, and the cutting excavated soil is easily discharged through the cutterhead opening, avoiding the accumulation and compaction in the front area. This fundamentally solves the risk of blockage caused by the inability of foam to act directly and timely on the working face in the existing system, reduces the fluctuation of cutterhead load and increases the tunneling speed.

[0038] In one embodiment, a first groove 250 is formed at the end of the cylinder 100 away from the cutter head, and a second groove 260 and a first engaging protrusion 270 are respectively formed on the outer walls of the two ends of the first connecting cylinder 220 along its length direction. The first engaging protrusion 270 is sealed and engaged with the first groove 250. A second snap-fit ​​protrusion 280 is formed on the inner wall of one end of the second connecting cylinder 240, and the second snap-fit ​​protrusion 280 is sealed and engaged with the second slot 260.

[0039] In this embodiment, the foam concentrate maintains a strict seal at each interface from the cylinder 100 to the first connecting cylinder 220 and then to the second connecting cylinder 240, preventing lateral escape of high-pressure foam or reverse intrusion of external soil particles at the connection interface. In the prior art, the cylinder 100 and connecting cylinder of the foam injection system are mostly connected by threads or welding. Under the long-term vibration and high-pressure pulsation conditions of the tunnel boring machine, loosening or small gaps are prone to occur, resulting in foam pressure attenuation, local turbulence and turbulence, and accumulation of soil particles at the interface, ultimately causing blockage of the entire injection channel. In this embodiment, the sealing engagement of the first locking protrusion 270 and the first locking groove 250, and the sealing engagement of the second locking protrusion 280 and the second locking groove 260, are formed by radial interference fit after axial pressing. Under the pressure of the foam concentrate, the sealing effect is further enhanced, allowing the foam to reach the foam injection space 210 completely at the design pressure and complete the two-stage refinement. The foam, with its high liquid content and small particle size, acts directly on the soil at the working face, rapidly penetrating the pores and forming a continuous liquid film. This effectively reduces the friction angle and cohesion within the soil, transforming the cutterhead into a stable fluid state and allowing it to be smoothly discharged from the cutterhead opening. This fundamentally prevents the accumulation and blockage of the cutting surface in the front area, reducing abnormal fluctuations in the cutterhead torque and the number of unplanned shutdowns.

[0040] In one embodiment, the foam ejection mechanism 300 includes: Foam extrusion disc 310 is installed at the end of the second connecting cylinder 240 away from the first connecting cylinder 220. Multiple second bubble-making holes 320 are arrayed on the foam extrusion disc 310, and the second bubble-making holes 320 are connected to the foam ejection space 210. A foam ejection disc 330 is installed at the end of the foam extrusion disc 310 away from the second connecting cylinder 240. Multiple baffle plates 340 are installed on the foam ejection disc 330. These baffle plates 340 are circumferentially spaced and enclose a ejection valve. The ejection valve is tapered away from the foam extrusion disc 310 along the extending direction of the cylinder 100. The fixed plate 350 is installed at the end of the foam ejection plate 330 away from the foam extrusion plate. The foam on the foam extrusion plate 310 can open the ejection valve and be ejected toward the working face.

[0041] Specifically, the cylinder 100, the first connecting cylinder 220, and the second connecting cylinder 240 are coaxially connected via a sealing engagement method using slots and locking protrusions, forming a continuous channel from the liquid inlet 120 to the foam ejection space 210. After the foam concentrate enters the cylinder 100 mounting space 110 via the foam supply unit 10, control valve, and pipeline, it undergoes initial mixing through the first bubble-forming holes 230 on the spherical protrusions of the first connecting cylinder 220 to generate foam, which then enters the foam ejection space 210. When the foam fills the ejection space and reaches a certain pressure, it passes through multiple second bubble-forming holes 320 arrayed on the foam extrusion disc 310, further refining and being squeezed into the chamber formed between the foam ejection disc 330 and the fixed disc 350. Subsequently, the foam pushes multiple circumferentially spaced baffles 340, causing the ejection valve to open from its initial closed state. The foam accelerates along the gradually narrowing ejection valve channel and is directly ejected in a high-pressure atomized form onto the face of the cutting head located in front of the cutter head.

[0042] Because the foam extrusion disc 310, foam spraying disc 330, and fixing disc 350 are sequentially assembled at the front end of the second connecting cylinder 240, the entire foam generation and spraying process occurs at the position closest to the tunnel face, greatly shortening the time from final foam generation to its application to the soil. In existing technologies, foam is mostly prefabricated at the rear of the main unit and transported through long-distance pipelines, resulting in significant foam collapse and poor penetration by the time it reaches the tunnel face. In this embodiment, the foam is first initially mixed through the first foaming hole 230, then further refined through the second foaming hole 320, and finally accelerated through a tapered spraying valve. This ensures that the foam uniformly covers the tunnel face with a high liquid content and small particle size, rapidly penetrating the soil pores and forming a continuous liquid film. This effectively reduces friction and cohesion within the soil, keeping the cut soil in a good fluid state, allowing it to smoothly enter the cutterhead opening and preventing caking and blockage in the area ahead. This process significantly reduces the peak cutterhead torque, decreases the number of abnormal shutdowns, and improves the continuity and efficiency of shield tunneling.

[0043] In one embodiment, the cylinder 100 includes; A third connecting cylinder 130, with an installation space 110 formed inside, a first retaining groove 250 formed at one end of the third connecting cylinder 130, and a liquid inlet 120 formed at the end of the third connecting cylinder 130 away from the first retaining groove 250; and, The connecting plate 140 is installed at the end of the third connecting cylinder 130 away from the first slot 250, and the first connecting plate 140 is connected to the cutter head.

[0044] Specifically, the spraying module 20 fixes the third connecting cylinder 130 to the front of the tunnel boring machine cutterhead via the connecting plate 140. The installation space 110 inside the cylinder 100 is connected to the foam supply unit 10 via a pipeline, and the control valve controls the flow of foam concentrate. The first slot 250 is located at the end of the third connecting cylinder 130 away from the cutterhead and forms a sealed engagement with the first engaging protrusion 270 of the first connecting cylinder 220. The second connecting cylinder 240, foam extrusion disc 310, foam spraying disc 330, and fixing disc 350 are sequentially assembled at the front end. When the control valve is opened, the foam concentrate enters the installation space 110 from the inlet 120 near the cutterhead end of the third connecting cylinder 130, is conveyed forward along the axial direction of the third connecting cylinder 130, and enters the first connecting cylinder 220 after reaching the first slot 250 away from the cutterhead end. Subsequently, the foam concentrate is injected into the foam ejection space 210 through the first bubble-forming holes 230 arrayed on the spherical protrusions, where it mixes with the compressed air introduced at the same time in a multi-point turbulent flow to generate preliminary foam. These foams continue to move forward and are further refined through multiple second bubble-forming holes 320 arrayed on the foam extrusion disc 310. Then, they push the multiple baffles 340 distributed circumferentially on the foam ejection disc 330 to open the tapered ejection valve, and finally, in a high-pressure atomized form, they are directly sprayed from the front end of the fixed disc 350 to the working face.

[0045] Due to the separate assembly structure of the third connecting cylinder 130 and the connecting plate 140, the third connecting cylinder 130 is rigidly fixed to the cutterhead through the connecting plate 140, ensuring that the coaxiality and stability of the entire injection channel are not affected during the rotation of the cutterhead. The foam concentrate enters from the inlet 120 near the cutterhead and is transported axially forward until it is generated and refined in the foam ejection space 210 at the foremost end. It then immediately acts on the soil at the working face through the tapered ejection valve. This process minimizes the time from foam generation to penetration, avoiding the problems of significant foam collapse and loss of activity caused by long-distance pipeline transportation after prefabrication at the rear of the main unit in existing technologies. The generated foam can uniformly penetrate into the pores of the soil at the tunnel face with a high liquid content and small particle size, quickly reducing the internal friction angle and cohesion of the soil, transforming the cut soil into a stable fluid plastic state, making it easier for the excavated soil to enter the cutterhead opening and be discharged. This effectively prevents the accumulation, hardening and blockage in the front area, reduces the fluctuation range of the cutterhead torque, reduces the number of abnormal shutdowns, and improves the efficiency of continuous tunneling.

[0046] In one embodiment, the third connecting cylinder 130 is further provided with a plurality of spheres, the diameter of which is larger than the diameter of the liquid inlet 120 and the first bubble-making hole 230.

[0047] In this embodiment, because the diameters of the multiple spheres are larger than the diameters of the inlet 120 and the first bubble-forming hole 230, after the foam concentrate enters the third connecting cylinder 130, the spheres cannot escape from the inlet 120 in the reverse direction, nor can they enter the subsequent channel through the first bubble-forming hole 230. Instead, they continuously roll, collide, and tumble within the installation space 110 with the liquid flow. This process allows the spheres to repeatedly impact and break up any larger soil clumps or agglomerates that enter with the foam concentrate, ensuring that only fully dispersed liquid phase components enter the first bubble-forming hole 230. In the prior art, the foam supply pipeline easily carries larger soil particles that have detached from the working face. These particles easily accumulate at the bubble-forming hole, causing blockages and leading to the failure of the entire injection module 20, thus forcing the tunnel boring machine to stop. In this embodiment, the continuous dynamic movement of the sphere inside the third connecting cylinder 130 not only breaks up potential blockages but also further promotes the premixing of the foam concentrate and compressed air through the local turbulence generated by the collision. This results in more uniform foam particle size and higher stability in the foam generated subsequently through the first foam-forming hole 230 and the second foam-forming hole 320. These foams can quickly penetrate into the pores of the soil at the tunnel face, forming a continuous liquid film and reducing the internal friction angle and cohesion of the soil. This transforms the cutting soil into a flowable plastic state, allowing it to be smoothly discharged from the cutterhead opening. This effectively avoids the accumulation of compacted soil in front, fundamentally solving the problem of construction interruption caused by easy clogging of the foam-forming holes in existing systems, ensuring the continuity of the tunneling process, and reducing cutterhead load fluctuations.

[0048] Based on the same technical concept, in a second aspect, the present invention also proposes a method for spraying anti-clogging foam for tunnel boring machine (TBM) construction, using the anti-clogging foam spraying method for TBM construction described in the first aspect, wherein the spraying method includes the following steps: S100. The foam concentrate supplied through the pipeline is prepared into foam to be sprayed using the spraying module. S200: Spray the foam to be sprayed toward the working face.

[0049] Specifically, the spraying module fixes the third connecting cylinder to the front of the tunnel boring machine cutterhead via a connecting plate. The third connecting cylinder contains multiple spheres with a diameter larger than the liquid inlet and the first foaming hole. The third connecting cylinder is sealed and engaged with the first connecting cylinder via a first slot. The second connecting cylinder is sequentially connected to the foam extrusion plate, the foam spraying plate, and the fixing plate. When the tunnel boring machine (TBM) begins its excavation operation, the control valve opens, and the foam concentrate enters the installation space through the inlet of the third connecting cylinder via pipeline. It continuously collides and rolls with multiple spheres inside the cylinder, achieving initial dispersion and premixing. Subsequently, the foam concentrate is injected into the foam ejection space through the array of first bubble-forming holes on the first connecting cylinder, where it generates initial foam under the action of multi-point turbulence with the synchronously introduced compressed air. These foams continue to move forward and undergo secondary refinement through the array of second bubble-forming holes on the foam extrusion disc, forming foam with uniform particle size and high liquid content to be ejected. After the ejected foam accumulates to a certain pressure, it pushes multiple baffles distributed circumferentially on the foam ejection disc, causing the tapered ejection valve to open. The foam is then sprayed directly from the front end of the fixed disc to the working face in a high-pressure atomized form.

[0050] This implementation process integrates the two core steps of foam preparation and final spraying into a spraying module located adjacent to the tunnel face. This avoids the problems of significant foam breakage and activity loss caused by pre-fabrication at the rear of the main unit and long-distance pipeline transportation, as seen in existing technologies. Because the spheres inside the third connecting cylinder break up any soil particles that may be carried, combined with the two-stage refining effect of the first and second foam-forming holes, the generated foam to be sprayed can rapidly penetrate the pores of the tunnel face soil in a small-particle-size, highly stable state, forming a continuous liquid film. This effectively reduces the internal friction angle and cohesion of the soil, keeping the cut soil in a good fluid state and allowing it to smoothly enter the cutterhead opening for discharge. This fundamentally prevents soil compaction and blockage in the forward area, significantly reduces peak fluctuations in cutterhead torque, decreases the number of abnormal shutdowns, and improves the continuity of tunnel boring and overall construction efficiency.

[0051] In one embodiment, prior to step S200, the method further includes: S300, Multiple steel balls are arranged in the spraying module; S400: Control the foam concentrate entering the spray module to drive the movement of the steel ball so that the foam is sprayed out in one direction toward the working face.

[0052] Specifically, the third connecting cylinder of the spraying module is fixed to the front of the tunnel boring machine cutterhead via a connecting plate. An installation space is formed within the third connecting cylinder, and multiple spheres with diameters larger than the inlet and the first bubble-forming hole are installed. The first connecting cylinder, the second connecting cylinder, the foam extrusion disc, the foam ejection disc, and the fixing disc are sequentially and coaxially sealed together. In implementing this method, multiple steel balls are first pre-placed within the installation space of the third connecting cylinder. Then, the control valve is opened, allowing the foam concentrate to enter the installation space through the inlet via a pipeline. The entering foam concentrate propels the steel balls in a continuous rolling and impacting motion along the axial and circumferential directions within the installation space. Because the steel balls have a diameter larger than the first bubble-forming hole, they cannot enter subsequent channels and are repeatedly propelled by the liquid flow, remaining within the third connecting cylinder. After the foam concentrate has fully collided and mixed with the steel balls, it passes sequentially through the first bubble-forming hole, the foam ejection space, and the second bubble-forming hole, ultimately pushing the baffle plate on the foam ejection disc to open the tapered ejection valve, causing the foam to be sprayed in a unidirectional, high-pressure atomized form towards the tunnel face.

[0053] This implementation process utilizes the continuous movement of steel balls driven by the foam concentrate to create a dynamic one-way valve effect, ensuring that the foam can only flow axially towards the tunnel face, preventing backflow or lateral leakage. In existing foam injection systems, frequent start-ups and shutdowns of the tunnel boring machine or fluctuations in ground pressure can lead to foam backflow, causing solidification and blockage of pipeline residues, or insufficient injection pressure preventing effective foam penetration into the tunnel face. In this embodiment, the steel balls are continuously propelled by the foam concentrate, creating high-frequency collisions and rolling within the third connecting cylinder. This not only breaks down larger soil particles entering with the liquid flow but also enhances the one-way propulsion effect of the foam through its dynamic blocking effect on the flow channel cross-section, ensuring that the final foam ejected from the converging ejection valve maintains a high outlet pressure and a uniform particle size distribution. These foams can quickly penetrate into the pores of the soil at the tunnel face, forming a stable liquid film and significantly reducing the internal friction angle and cohesion of the soil. This transforms the cut soil into a fluid plastic state that is easy to discharge, thereby effectively preventing the soil in front from hardening and accumulating. It fundamentally solves the technical problems of poor unidirectionality of foam injection and easy backflow and blockage in existing methods, ensuring the continuous and stable operation of the shield tunneling process and reducing abnormal fluctuations in the cutterhead load.

[0054] The above description is merely an exemplary embodiment of the present invention and does not limit the scope of the present invention. Any equivalent structural transformations made based on the technical concept of the present invention and the contents of the specification and drawings of the present invention, or direct / indirect applications in other related technical fields, are included within the protection scope of the present invention.

Claims

1. A foam spraying system for shield tunneling construction to prevent clogging, characterized in that, include: A foam supply unit, wherein the foam supply unit stores foam concentrate; as well as, The spraying module is installed on the cutterhead of the tunnel boring machine. The foam spraying end of the spraying module is positioned facing the working face in front of the cutterhead. The spraying module is connected to the foam supply unit through a pipeline. A control valve is installed on the pipeline. The control valve can switch between an open state and a closed state, which opens the pipeline and sprays the foam concentrate toward the working face.

2. The anti-clogging foam spraying system for shield tunneling construction as described in claim 1, characterized in that, The spraying module includes: A cylinder, one end of which is bolted to the cutterhead of the tunnel boring machine, an installation space is formed inside the cylinder, the cylinder extends from the cutterhead toward the working face in front of the cutterhead, and a liquid inlet communicating with the installation space is formed at the end of the cylinder near the cutterhead. A foam forming mechanism is installed at the end of the installation space away from the cutter head. A foam ejection space is formed within the foam forming mechanism. The foam forming mechanism can process foam concentrate entering the installation space through the inlet into foam and inject it into the foam ejection space. The end of the foam forming mechanism away from the cylinder forms a foam ejection end. A foam ejection mechanism is installed at the foam ejection end, and the foam ejection space can eject the foam formed and injected by the foam forming mechanism from the foam ejection mechanism toward the working face.

3. The anti-clogging foam spraying system for shield tunneling construction as described in claim 2, characterized in that, The foam forming mechanism includes: A first connecting cylinder, one end of which engages with the end of the cylinder body away from the cutter head, and a first bubble-forming hole is formed at the end of the first connecting cylinder away from the mounting space; and... The second connecting tube is installed at the end of the first connecting tube away from the cylinder body. The foam ejection space is formed between the second connecting tube and the first firing hole of the first connecting tube. The cylinder body, the first connecting tube and the second connecting tube extend in the same direction.

4. The anti-clogging foam spraying system for shield tunneling construction as described in claim 3, characterized in that, The end of the first connecting cylinder away from the cylinder body protrudes towards the end away from the cylinder body and forms a spherical protrusion, on which the first bubble-forming hole is formed; There are multiple first bubble-forming holes, and the array of multiple first bubble-forming holes is distributed on the spherical protrusion.

5. The anti-clogging foam spraying system for shield tunneling construction as described in claim 4, characterized in that, The end of the cylinder away from the cutter head has a first groove, and the outer walls of the two ends of the first connecting cylinder along its length direction have a second groove and a first snap-fit ​​protrusion, respectively. The first snap-fit ​​protrusion is sealed and engaged with the first groove. A second snap-fit ​​protrusion is formed on the inner wall of one end of the second connecting cylinder, and the second snap-fit ​​protrusion is sealed and engaged with the second slot.

6. The anti-clogging foam spraying system for shield tunneling construction as described in claim 5, characterized in that, The foam ejection mechanism includes: A foam extrusion disc is installed at the end of the second connecting cylinder away from the first connecting cylinder. The foam extrusion disc has a plurality of second bubble-forming holes arranged in an array, and the second bubble-forming holes are in communication with the foam ejection space. A foam ejection disc is installed at the end of the foam extrusion disc away from the second connecting cylinder. Multiple baffle plates are installed on the foam ejection disc, and these baffle plates are spaced apart circumferentially and surround to form an ejection valve. The ejection valve is tapered away from the foam extrusion disc along the extending direction of the cylinder. A fixed plate is installed at the end of the foam ejection plate away from the foam extrusion plate, and the foam on the base of the foam extrusion plate can open the ejection valve and be ejected toward the working face.

7. The anti-clogging foam spraying system for shield tunneling construction as described in claim 6, characterized in that, The cylindrical body includes; A third connecting cylinder, wherein the mounting space is formed within the third connecting cylinder, one end of the third connecting cylinder forms the first retaining groove, and the end of the third connecting cylinder away from the first retaining groove forms a liquid inlet; and... A connecting plate is installed at the end of the third connecting cylinder away from the first slot, and the first connecting plate is connected to the cutter head.

8. The anti-clogging foam spraying system for shield tunneling construction as described in claim 7, characterized in that, The third connecting cylinder is also provided with a plurality of spheres, the diameter of which is larger than the diameter of the liquid inlet and the first bubble-forming hole.

9. A method for spraying anti-clogging foam during shield tunneling construction, characterized in that, The anti-clogging foam spraying method for tunnel boring machine construction as described in any one of claims 1 to 8, the spraying method comprising the following steps: The spraying module is used to prepare the foam concentrate supplied through the pipeline into foam to be sprayed. The foam to be sprayed is sprayed toward the working face.

10. The anti-clogging foam spraying method for shield tunneling construction as described in claim 9, characterized in that, Before the step of spraying the foam to be sprayed toward the working face, the method further includes: Multiple steel balls are arranged inside the spraying module; The foam concentrate entering the spraying module is controlled to drive the movement of the steel balls so that the foam is sprayed out in one direction toward the working face.

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