Shield muck improvement method for water-rich coarse-particle stratum

Abstract

The invention provides a shield muck improvement method for a water-rich coarse-particle stratum, and relates to the technical field of shield muck improvement, and the method comprises the following steps: calculating the volume Vs of a soil body cut by a cutter head of a shield tunneling machine in unit time according to the excavation diameter D and the tunneling speed v of the shield tunneling machine and the loose coefficient K of the coarse-particle stratum; calculating the flow q of the calcium-based clay mineral-sodium silicate mixed slurry in unit time by combining Vs with the injection ratio KIR; according to the preset volume ratio M of the calcium-based clay mineral slurry to the sodium silicate solution and the number N and q of the mixing containers, the flow qK and qG of the two raw materials in the single mixing container in unit time are calculated; starting a shield tunneling machine, pumping the two raw materials into a mixing container according to qK and qG by a pumping device to prepare mixed slurry, and injecting the mixed slurry into a soil bin to be mixed with shield muck. The mixed slurry mixes the shield muck with underground water by virtue of good bonding capacity, improves the plastic flow state of the muck, reduces the permeability, and avoids spewing and stagnant discharge of the muck, so that the stability of a tunnel face is guaranteed.

Description

Technical Field

[0001] This application relates to the field of shield tunneling spoil remediation, and more particularly to a method for remediating shield tunneling spoil in water-rich, coarse-grained strata. Background Technology

[0002] Earth pressure balance (EPB) shield tunneling has rapidly become a major construction method for urban tunnels due to its advantages in safety, efficiency, and economy. Especially in recent years, thanks to the rapid development of soil improvement technology, EPB shield tunneling has been successfully applied to various geological formations. During shield tunneling, the tunnel boring machine (TBM) cuts through the strata with its cutterhead. Conventional soil improvement methods typically mix the excavated soil from the cutterhead with materials such as foam, bentonite slurry, and polymers to form improved soil, which serves as a support medium to resist the water and soil pressure in front of the tunnel face. This improved soil can then be transported in a controlled manner via a screw conveyor to a belt conveyor and discharged from the tunnel. However, conventional soil improvement methods are insufficient to effectively reduce the permeability of the soil. The soil has extremely poor plasticity, and when the TBM traverses water-rich, coarse-grained strata, it presents a "soil and water" state, leading to frequent problems of gushing and soil stagnation, which can cause face instability and even surface collapse.

[0003] To address this issue, this application proposes a method for improving the excavated soil in water-rich, coarse-grained strata of shield tunnels to ensure the stability of the tunnel face. Summary of the Invention

[0004] The purpose of this application is to provide a method for improving shield tunneling excavated soil in water-rich, coarse-grained strata, in response to the above problems.

[0005] This application provides a method for improving shield tunnel excavated soil in water-rich, coarse-grained strata, including: S1: Calculate the volume of soil Vs cut by the tunnel boring machine cutterhead per unit time based on the tunneling diameter D, tunneling speed v, and loosening coefficient K of the coarse-grained stratum. S2: Calculate the flow rate q of the calcium-based clay mineral-sodium silicate mixed slurry per unit time based on the volume of soil cut by the tunnel boring machine cutterhead Vs and the injection ratio KIR per unit time. S3: Based on the preset volume ratio M of calcium-based clay mineral slurry to sodium silicate solution, the number of mixing containers N, and the flow rate q of the calcium-based clay mineral-sodium silicate mixed slurry per unit time, calculate the flow rate q of the calcium-based clay mineral slurry per unit time in a single mixing container. K And the flow rate q of the sodium silicate solution per unit time in a single mixing container. G The mixing container is used to mix the calcium-based clay mineral slurry fed into the first raw material silo and the sodium silicate solution fed into the second raw material silo. S4: Start the tunnel boring machine. The pumping device operates according to the flow rate q of the calcium-based clay mineral slurry per unit time. K And the flow rate q of sodium silicate solution per unit time G Simultaneously, the calcium-based clay mineral slurry in the first raw material silo and the sodium silicate solution in the second raw material silo are pumped into a mixing container to form a calcium-based clay mineral-sodium silicate mixed slurry. The calcium-based clay mineral-sodium silicate mixed slurry is then injected into the soil chamber of the tunnel boring machine to mix with the tunnel boring machine's excavated soil.

[0006] According to the technical solutions provided in certain embodiments of this application, before S1, the method further includes: According to the preset mass ratio of water to calcium-based clay mineral powder, calcium-based clay mineral powder and water are added to the first raw material silo; Stir the calcium-based clay mineral powder and water in the first raw material silo until a calcium-based clay mineral slurry is formed; Add sodium silicate solution to the second raw material silo.

[0007] According to the technical solutions provided in certain embodiments of this application, after S4, the method further includes: S5: At preset time intervals, take a mixture of calcium-based clay mineral-sodium silicate slurry and shield excavated soil from the conveyor belt of the tunnel boring machine and conduct an on-site slump test. Adjust the injection ratio KIR according to the slump value so that the slump value is greater than or equal to 15cm and less than or equal to 20cm.

[0008] According to the technical solutions provided in certain embodiments of this application, adjusting the injection ratio KIR based on the slump value to make the slump value greater than or equal to 15 cm and less than or equal to 20 cm includes: If the slump value is less than 15 cm, then increase the injection ratio by 5% and repeat S2-S5 until the slump value is greater than or equal to 15 cm and less than or equal to 20 cm. If the slump value is greater than 20 cm, reduce the injection ratio by 5% and repeat S2-S5 until the slump value is greater than or equal to 15 cm and less than or equal to 20 cm.

[0009] According to the technical solutions provided in certain embodiments of this application, the preset mass ratio of water to calcium-based clay mineral powder is 3:1.

[0010] According to the technical solutions provided in certain embodiments of this application, the preset volume ratio M of the calcium-based clay mineral slurry to the sodium silicate solution is 10:1 to 7:1.

[0011] According to the technical solutions provided in certain embodiments of this application, the injection ratio KIR is 10%~20%.

[0012] According to the technical solutions provided in some embodiments of this application, the number N of the mixing containers is 1 to 4.

[0013] According to the technical solutions provided in some embodiments of this application, the preset time period is 1 to 5 minutes.

[0014] According to the technical solutions provided in certain embodiments of this application, the pumping pressures of the calcium-based clay mineral slurry in the first raw material silo and the sodium silicate solution in the second raw material silo are equal and greater than the pressure inside the soil chamber of the tunnel boring machine.

[0015] This application provides a method for improving tunnel boring machine (TBM) excavation slag in water-rich, coarse-grained strata, comprising: S1: calculating the volume Vs of soil cut by the TBM cutterhead per unit time based on the TBM's excavation diameter D, tunneling speed v, and the loosening coefficient K of the coarse-grained strata; S2: calculating the flow rate q of the calcium-based clay mineral-sodium silicate mixed slurry per unit time based on the volume Vs of soil cut by the TBM cutterhead per unit time and the injection ratio KIR; S3: calculating the flow rate q of the calcium-based clay mineral slurry per unit time in a single mixing container based on the preset volume ratio M of the calcium-based clay mineral slurry to the sodium silicate solution, the number of mixing containers N, and the flow rate q of the calcium-based clay mineral-sodium silicate mixed slurry per unit time. K And the flow rate q of the sodium silicate solution per unit time in a single mixing container. G The mixing container is used to mix the calcium-based clay mineral slurry input from the first raw material silo and the sodium silicate solution input from the second raw material silo; S4: Start the tunnel boring machine, and the pumping device operates according to the flow rate q of the calcium-based clay mineral slurry per unit time. K And the flow rate q of sodium silicate solution per unit time G Simultaneously, the calcium-based clay mineral slurry from the first raw material silo and the sodium silicate solution from the second raw material silo are pumped into a mixing container to form a calcium-based clay mineral-sodium silicate mixed slurry. This slurry is then injected into the tunnel boring machine's (TBM) soil chamber to mix with the TBM excavation. Utilizing the excellent binding capacity of the calcium-based clay mineral-sodium silicate mixed slurry, the TBM excavation and groundwater are integrated, allowing larger pieces of excavation to be trapped within it. This transforms the originally dispersed and easily stuck large particles of excavation into a more fluid slurry, facilitating its discharge by the screw conveyor and preventing accumulation at the bottom of the soil chamber that could clog the conveyor. Furthermore, because finer particles of excavation are not lost, they effectively fill the pores between larger pieces of excavation, reducing the permeability coefficient and preventing blowouts, thus ensuring the stability of the tunnel face.

[0016] It should be understood that the descriptions of technical features, technical solutions, beneficial effects, or similar language in this application do not imply that all features and advantages can be achieved in any single embodiment. Rather, it is understood that the description of a feature or beneficial effect means that a specific technical feature, technical solution, or beneficial effect is included in at least one embodiment. Therefore, the descriptions of technical features, technical solutions, or beneficial effects in this specification do not necessarily refer to the same embodiment. Furthermore, the technical features, technical solutions, and beneficial effects described in this embodiment can be combined in any suitable manner. Those skilled in the art will understand that embodiments can be implemented without one or more specific technical features, technical solutions, or beneficial effects of a particular embodiment. In other embodiments, additional technical features and beneficial effects may be identified in specific embodiments that do not embody all embodiments. Attached Figure Description

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

[0018] Figure 1 A schematic diagram of shield tunnel face instability under a conventional slag improvement method provided in this application embodiment; Figure 2 A schematic flowchart illustrating a method for improving tunnel excavation soil in water-rich, coarse-grained strata, provided in an embodiment of this application. Figure 3 A schematic diagram illustrating the process of improving shield tunneling slag using a calcium-based clay mineral-sodium silicate mixed slurry, as provided in this application embodiment.

[0019] The text labels in the image represent: 1. Mixing container; 2. First raw material silo; 3. Second raw material silo; 4. Pumping device; 5. Soil silo; 6. Screw conveyor; 7. Water-rich coarse-grained stratum; 8. Muddy water; 9. Collapse cavity. Detailed Implementation

[0020] To enable those skilled in the art to better understand the technical solutions of this application, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. The descriptions in this section are merely illustrative and explanatory, and should not be construed as limiting the scope of protection of this application. Specifically, the described embodiments are only some embodiments of this application, not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort should fall within the scope of protection of this application.

[0021] It should be noted that similar reference numerals and letters in the following figures denote similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such process, method, product, or apparatus.

[0022] When a tunnel boring machine (TBM) is excavating in the water-rich, coarse-grained stratum 7, the excavated soil must be able to resist the water and soil pressure in front of the tunnel face and be discharged in a controlled manner through the screw conveyor 6. This requires the excavated soil to have low permeability and suitable plasticity. However, conventional excavated soil improvement methods are difficult to effectively improve the water-rich, coarse-grained stratum 7, such as... Figure 1 As shown, the shield tunneling excavation soil is in a state of "excavation soil and water water". Large chunks of shield tunneling excavation soil are stuck at the bottom of the soil chamber 5, while the ground water, together with some fine-particle shield tunneling excavation soil, turns into muddy water 8 and fills the upper part of the soil chamber 5. Under the action of water pressure, the muddy water 8 will spray out from the screw conveyor 6 outlet through the gaps of the large chunks of shield tunneling excavation soil at the bottom, causing a gushing accident, which in turn induces the instability of the tunnel face and causes the formation of collapse cavities 9.

[0023] In view of this, in order to solve the above problems, such as Figure 2 and Figure 3 As shown in the figure, this embodiment provides a method for improving shield tunneling excavated soil in water-rich, coarse-grained strata, including: S1: Calculate the volume of soil Vs cut by the tunnel boring machine cutterhead per unit time based on the tunneling diameter D, tunneling speed v, and loosening coefficient K of the coarse-grained stratum. Specifically, the calculation method for the volume of soil Vs cut by the cutterhead of the tunnel boring machine per unit time is shown in the following formula (1): Formula (1) Where Vs is the volume of soil cut by the tunnel boring machine cutterhead per unit time, K is the loosening coefficient of coarse-grained strata, D is the excavation diameter of the tunnel boring machine, and v is the tunneling speed of the tunnel boring machine.

[0024] The loosening coefficient K of coarse-grained strata refers to the ratio of the volume of soil after excavation or blasting to the volume in its original state. The loosening coefficient K varies for different types of soil and needs to be determined based on field tests.

[0025] S2: Calculate the flow rate q of the calcium-based clay mineral-sodium silicate mixed slurry per unit time based on the volume of soil cut by the tunnel boring machine cutterhead Vs and the injection ratio KIR per unit time. Specifically, the calculation method for the flow rate q per unit time of the calcium-based clay mineral-sodium silicate mixed slurry is shown in the following formula (2): Formula (2) Where q is the flow rate of the calcium-based clay mineral-sodium silicate mixed slurry per unit time, Vs is the volume of soil cut by the tunnel boring machine cutterhead per unit time, and KIR is the injection ratio.

[0026] S3: Based on the preset volume ratio M of calcium-based clay mineral slurry to sodium silicate solution, the number of mixing containers 1 N, and the flow rate q of the calcium-based clay mineral-sodium silicate mixed slurry per unit time, calculate the flow rate q of the calcium-based clay mineral slurry per unit time in a single mixing container 1. K And the flow rate q of the sodium silicate solution per unit time in a single mixing container 1. G The mixing container 1 is used to mix the calcium-based clay mineral slurry input from the first raw material silo 2 and the sodium silicate solution input from the second raw material silo 3. Specifically, one mixing container 1 is sufficient for shield tunneling muck modification operations. However, using multiple mixing containers 1 can improve the injection efficiency of the calcium-based clay mineral-sodium silicate mixed slurry. Therefore, the flow rate q of the calcium-based clay mineral slurry per unit time in a single mixing container 1 is... K The calculation method is shown in the following formula (3): Formula (3) Where, q K q represents the flow rate of the calcium-based clay mineral slurry per unit time, M represents the preset volume ratio of the calcium-based clay mineral slurry to the sodium silicate solution, N represents the number of mixing containers 1, and q represents the flow rate of the calcium-based clay mineral-sodium silicate mixed slurry per unit time.

[0027] The flow rate q of the sodium silicate solution per unit time in a single mixing container 1 G The calculation method is shown in the following formula (4): Formula (4) Where, q G q represents the flow rate of the calcium-based clay mineral slurry per unit time, M represents the preset volume ratio of the calcium-based clay mineral slurry to the sodium silicate solution, N represents the number of mixing containers 1, and q represents the flow rate of the calcium-based clay mineral-sodium silicate mixed slurry per unit time.

[0028] S4: Start the tunnel boring machine. Pumping device 4 operates according to the flow rate q of the calcium-based clay mineral slurry per unit time. K And the flow rate q of sodium silicate solution per unit time GSimultaneously, the calcium-based clay mineral slurry in the first raw material silo 2 and the sodium silicate solution in the second raw material silo 3 are pumped into the mixing container 1 to form a calcium-based clay mineral-sodium silicate mixed slurry. The calcium-based clay mineral-sodium silicate mixed slurry is then injected into the soil chamber 5 of the tunnel boring machine to mix with the tunnel boring machine's excavated soil.

[0029] Specifically, such as Figure 3 As shown, the tunnel boring machine is started, and the pumping device 4 operates according to the flow rate q of the calcium-based clay mineral slurry per unit time. K And the flow rate q of sodium silicate solution per unit time G Simultaneously, the calcium-based clay mineral slurry from the first raw material bin 2 and the sodium silicate solution from the second raw material bin 3 are pumped into the mixing container 1. The simultaneous pumping of the calcium-based clay mineral slurry and the sodium silicate solution ensures that their pumping times are equal, thereby guaranteeing that their flow rate ratio is equal to their volume ratio. This allows them to form a calcium-based clay mineral-sodium silicate mixed slurry according to a preset volume ratio M. This mixed slurry is then injected into the tunnel boring machine's soil chamber 5 to mix with the tunnel boring machine's excavated soil, forming a mixture of calcium-based clay mineral-sodium silicate mixed slurry and tunnel boring machine excavated soil. The tunnel boring machine's excavated soil generated during tunneling directly enters its soil chamber 5; while the pumping device 4 first pumps the calcium-based clay mineral slurry and sodium silicate solution into the mixing container 1 for mixing, and then transports the mixed slurry to the soil chamber 5 to mix with the tunnel boring machine excavated soil within the soil chamber 5. The pumping device 4 can be an electric pressure pump, or other equipment capable of performing the above functions; no specific limitation is made here.

[0030] This application involves mixing calcium-based clay mineral slurry and sodium silicate solution in a predetermined ratio to form a calcium-based clay mineral-sodium silicate mixed slurry, which is then injected into the tunnel boring machine's (TBM) soil chamber. This mixes the slag and excavated material in the TBM soil chamber. Utilizing the excellent binding ability of the calcium-based clay mineral-sodium silicate mixed slurry, the excavated material and groundwater are integrated, allowing larger pieces of excavated material to be trapped within it. This transforms the originally dispersed and easily stuck large particles of excavated material into a more fluid slurry, facilitating its discharge by the screw conveyor and preventing the accumulation of excavated material at the bottom of the soil chamber, which could cause blockages. Simultaneously, because fine particles of excavated material are not lost, they effectively fill the pores between larger pieces of excavated material, reducing the permeability coefficient of the excavated material and preventing blowout accidents, thereby ensuring the stability of the tunnel face.

[0031] In a preferred embodiment, prior to S1, the method further includes: According to the preset mass ratio of water to calcium-based clay mineral powder, calcium-based clay mineral powder and water are added to the first raw material silo 2; Stir the calcium-based clay mineral powder and water in the first raw material silo 2 until a calcium-based clay mineral slurry is formed; Add sodium silicate solution to the second raw material silo 3.

[0032] Specifically, such as Figure 3 As shown, before mixing the calcium-based clay mineral slurry and sodium silicate solution in mixing container 1, the calcium-based clay mineral slurry and sodium silicate solution should be prepared. According to the preset mass ratio of water to calcium-based clay mineral powder, calcium-based clay mineral powder and water are added to the first raw material silo 2. The calcium-based clay mineral powder and water in the first raw material silo 2 are stirred until a calcium-based clay mineral slurry is formed. The calcium-based clay mineral powder and water should be thoroughly stirred to ensure the uniformity of the calcium-based clay mineral slurry; the stirring time can be controlled to 5-10 minutes. Sodium silicate solution is added to the second raw material silo 3. By placing the calcium-based clay mineral slurry and sodium silicate solution in separate silos, premature contact and reaction between the two substances can be avoided, and subsequent pumping as needed can be facilitated.

[0033] In a preferred embodiment, after S4, the method further includes: S5: At preset time intervals, take a mixture of calcium-based clay mineral-sodium silicate slurry and shield excavated soil from the conveyor belt of the tunnel boring machine and conduct an on-site slump test. Adjust the injection ratio KIR according to the slump value so that the slump value is greater than or equal to 15cm and less than or equal to 20cm.

[0034] Specifically, testing the mixture of calcium-based clay mineral-sodium silicate slurry and tunnel boring machine (TBM) excavated soil at preset time intervals allows sufficient reaction time for both materials to react before testing, thus improving accuracy. Simultaneously, it enables real-time monitoring of the mixture's stability, preventing construction failures due to material ratio fluctuations. Limiting the slump value to 15cm or greater and 20cm or less is a common standard for judging material flowability through slump testing. A slump value that is too low (<15cm) indicates poor flowability, leading to hardened excavated soil that can clog conveyor belts or screw conveyors, causing construction stoppages. A slump value that is too high (>20cm) indicates excessive flowability, making it difficult to effectively resist the water and soil pressure in the TBM's forward direction, potentially causing instability at the tunnel face. The belt conveyor of the tunnel boring machine (not shown in the figure) is usually connected to the screw conveyor 6 at one end and a muck truck at the other end. It is used to transport the muck from the screw conveyor 6 over long distances and with high efficiency to the outside of the tunnel to complete the muck removal process.

[0035] In a preferred embodiment, adjusting the injection ratio KIR according to the slump value so that the slump value is greater than or equal to 15 cm and less than or equal to 20 cm includes: If the slump value is less than 15 cm, then increase the injection ratio by 5% and repeat S2-S5 until the slump value is greater than or equal to 15 cm and less than or equal to 20 cm. If the slump value is greater than 20 cm, reduce the injection ratio by 5% and repeat S2-S5 until the slump value is greater than or equal to 15 cm and less than or equal to 20 cm.

[0036] Specifically, if the slump value is less than 15 cm, it indicates that the fluidity of the mixture is poor, and the calcium-based clay mineral-sodium silicate slurry does not bind the shield excavation soil well, making the shield excavation soil still relatively loose. Therefore, the injection ratio KIR is increased by 5%, and S2-S5 are repeated until the slump value is greater than or equal to 15 cm and less than or equal to 20 cm. If the slump value is greater than 20 cm, it indicates that the fluidity of the mixture is too strong. Therefore, the injection ratio KIR is decreased by 5%, and S2-S5 are repeated until the slump value is greater than or equal to 15 cm and less than or equal to 20 cm.

[0037] In a preferred embodiment, the preset mass ratio of water to calcium-based clay mineral powder is 3:1.

[0038] Specifically, the preset mass ratio of water to calcium-based clay mineral powder is 3:1. This ratio allows the calcium-based clay mineral powder to be fully dispersed in the water, preventing clumping or uneven dispersion, thus laying the foundation for subsequent steps. Simultaneously, the calcium-based clay mineral-sodium silicate mixed slurry formed at this ratio has the best effect on improving the permeability and fluidity of the slag. The preset mass ratio of water to calcium-based clay mineral powder was obtained from field tests and can be adjusted according to actual site conditions during operation.

[0039] In a preferred embodiment, the preset volume ratio M of the calcium-based clay mineral slurry to the sodium silicate solution is 10:1 to 7:1.

[0040] Specifically, the preset volume ratio M of the calcium-based clay mineral slurry to the sodium silicate solution is 10:1 to 7:1. Within this ratio range, the calcium-based clay mineral-sodium silicate mixed slurry has the best effect on improving the permeability and fluidity of the tunnel boring machine excavation soil. The preset volume ratio M of the calcium-based clay mineral slurry to the sodium silicate solution is obtained from field tests and can be adjusted according to the actual field conditions during actual operation.

[0041] In a preferred embodiment, the injection ratio KIR is 10% to 20%.

[0042] Specifically, setting the injection ratio KIR clarifies the starting point of the experiment and provides a basis for subsequent calculations of the flow rate of calcium-based clay mineral slurry and sodium silicate solution per unit time. Setting the injection ratio KIR to 10%~20% is based on industry experience, which can reduce the number of invalid experiments and avoid entering an obviously erroneous range from the beginning. It only requires fine-tuning within a certain range, which saves more time, materials and labor costs compared to trial and error from scratch.

[0043] In a preferred embodiment, the number N of the mixing containers 1 is 1 to 4.

[0044] Specifically, one mixing container 1 is sufficient for shield tunneling excavation soil modification operations. However, using multiple mixing containers 1 can improve the injection efficiency of the calcium-based clay mineral-sodium silicate mixed slurry. However, the limitations of the actual working space should also be considered. Therefore, the number N of mixing containers 1 is determined to be 1 to 4. When there are multiple mixing containers 1, they are distributed to different locations in the soil chamber 5 to ensure uniform mixing of the calcium-based clay mineral-sodium silicate mixed slurry with the shield tunneling excavation soil within the soil chamber 5.

[0045] In a preferred embodiment, the preset time period is 1 to 5 minutes.

[0046] Specifically, the preset time period is set to 1-5 minutes, mainly based on the initial setting time of the calcium-based clay mineral-sodium silicate mixed slurry and the pumping time of the mixed slurry. At this time interval, samples are taken from the tunnel boring machine's conveyor belt every 1-5 minutes (the samples are a mixture of the calcium-based clay mineral-sodium silicate mixed slurry and the tunnel boring machine's excavated soil). This ensures that the pumping device 4 has successfully delivered the calcium-based clay mineral-sodium silicate mixed slurry into the soil chamber 5, and also ensures that the initial setting process of the calcium-based clay mineral-sodium silicate mixed slurry occurs in the soil chamber 5, rather than prematurely setting in the mixing container 1, thus avoiding blockage problems in the mixing container 1.

[0047] In a preferred embodiment, the pumping pressures of the calcium-based clay mineral slurry in the first raw material silo 2 and the sodium silicate solution in the second raw material silo 3 into the mixing container 1 are equal and both are greater than the pressure inside the soil chamber 5 of the tunnel boring machine.

[0048] Specifically, the pumping pressures of the calcium-based clay mineral slurry in the first raw material silo 2 and the sodium silicate solution in the second raw material silo 3 into the mixing container 1 are equal. This ensures stable flow rates and precise proportions of the two raw materials during their entry into the mixing container 1, preventing one material from being transported too quickly or too slowly due to pressure differences, which could affect the final performance of the mixed slurry and guarantee the subsequent soil improvement effect. Both pumping pressures are greater than the pressure inside the soil chamber 5 of the tunnel boring machine, allowing the calcium-based clay mineral slurry and sodium silicate solution to enter the soil chamber 5 and mix with the tunnel boring machine's excavated soil under this pressure. Simultaneously, it prevents the excavated soil or gas in the soil chamber 5 from flowing back into the mixing container 1. This ensures the stability of the calcium-based clay mineral slurry and sodium silicate solution transport process and avoids raw material contamination and blockage of the transport pipelines, thereby ensuring the normal progress of the tunnel boring machine construction.

[0049] This application mixes calcium-based clay mineral slurry with sodium silicate solution at a predetermined volume ratio to prepare a calcium-based clay mineral-sodium silicate mixed slurry. This slurry is injected into the soil chamber of a tunnel boring machine (TBM) and mixed with the TBM excavation material inside. Utilizing the excellent binding properties of this mixed slurry, the TBM excavation material and groundwater are tightly integrated, encapsulating large pieces of TBM excavation material within the slurry. This transforms the originally dispersed and easily stuck large particles of TBM excavation material into a more fluid slurry, facilitating smooth discharge via a screw conveyor and preventing screw conveyor blockage caused by TBM excavation material accumulating at the bottom of the soil chamber. Simultaneously, the fine particles of TBM excavation material do not leak out and can fully fill the pores of the larger TBM excavation material, effectively reducing the permeability coefficient of the TBM excavation material and thus preventing blowout accidents, ultimately ensuring the stability of the tunnel face. Unmodified coarse-grained slag is dispersed and hard. During tunneling, the cutterhead of the tunnel boring machine (TBM) has to overcome the compression, friction, and obstruction of slag particles. Modified slag, on the other hand, is pasty and has uniform stress, which reduces the friction and resistance that the cutterhead has to overcome, thereby extending the service life of the TBM cutterhead.

[0050] To facilitate understanding by those skilled in the art, the workflow of the shield tunneling spoil improvement method for water-rich, coarse-grained strata provided in this application is as follows: Water and calcium-based clay mineral powder are added to the first raw material silo 2 at a preset mass ratio of 3:1 and stirred to form a calcium-based clay mineral slurry. Simultaneously, sodium silicate solution is added to the second raw material silo 3. The volume of soil cut by the cutterhead per unit time, Vs, is calculated based on the tunnel boring machine's excavation diameter D, tunneling speed v, and the loosening coefficient K of the coarse-grained strata. The flow rate q of the calcium-based clay mineral-sodium silicate mixed slurry per unit time is determined based on the volume of soil cut by the cutterhead per unit time, Vs, and an injection ratio KIR of 10%~20%. The flow rate q of the clay slurry per unit time is calculated based on the volume ratio M of clay slurry to sodium silicate solution of 10:1~7:1, the number of mixing containers N, and the flow rate q of the calcium-based clay mineral-sodium silicate mixed slurry per unit time. K The flow rate q of sodium silicate solution per unit time G Start the tunnel boring machine, and pumping device 4 operates at a rate of q for the clay slurry per unit time. K The flow rate q of sodium silicate solution per unit time G The raw materials from the first raw material bin 2 and the second raw material bin 3 are simultaneously pumped into the mixing container 1 at a pumping pressure equal to and greater than the internal pressure of the soil bin 5 to form a calcium-based clay mineral-sodium silicate mixed slurry, which is then injected into the soil bin 5 to mix with the slag. A slump test is conducted on the mixture of calcium-based clay mineral-sodium silicate mixed slurry and shield slag on the belt conveyor of the tunnel boring machine. The injection ratio KIR is adjusted according to the slump value (if the slump is less than 15cm, the injection ratio KIR is increased by 5%; if it is greater than 20cm, it is decreased by 5%, and the test is repeated) so that the slump value is greater than or equal to 15cm and less than or equal to 20cm.

[0051] This application involves mixing calcium-based clay mineral slurry with sodium silicate solution at a predetermined volume ratio to prepare a calcium-based clay mineral-sodium silicate mixed slurry. This slurry is injected into the tunnel boring machine's (TBM) soil chamber and mixed with the TBM excavation material inside. Through the excellent binding properties of this mixed slurry, the TBM excavation material can be tightly bound to groundwater. This not only encapsulates large pieces of TBM excavation material within the slurry, transforming the originally dispersed and easily stuck large particles into a more fluid slurry, which can then be smoothly discharged via a screw conveyor, solving the problem of screw conveyor blockage caused by TBM excavation material accumulating at the bottom of the soil chamber, but also prevents the loss of fine-grained TBM excavation material. This effectively fills the pores between large pieces of TBM excavation material, reducing the permeability coefficient of the TBM excavation material and thus preventing blowout accidents, ultimately ensuring the stability of the tunnel face. In addition, the unmodified coarse-grained shield tunneling soil is dispersed and hard. When the shield machine is tunneling, the cutterhead rotation has to overcome the squeezing and friction between soil particles and the obstruction of large pieces of soil. However, the modified shield tunneling soil is pasty and has a uniform internal stress distribution. The friction and resistance that the cutterhead needs to overcome when rotating is greatly reduced. This change also extends the service life of the shield machine cutterhead.

[0052] This document uses specific examples to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this application. The above descriptions are only preferred embodiments of this application. It should be noted that due to the limitations of written expression, while there are objectively infinite specific structures, those skilled in the art can make several improvements, modifications, or changes without departing from the principles of this application, and can also combine the above technical features in an appropriate manner. These improvements, modifications, changes, or combinations, or the direct application of the inventive concept and technical solution to other situations without modification, should all be considered within the scope of protection of this application.

Claims

1. A method of improving a shield muck in a water-rich coarse-grained formation, characterized by, The method comprises: S1: calculating the volume Vs of the soil cut by the cutter head of the shield machine per unit time according to the excavation diameter D of the shield machine, the tunneling speed v and the loose coefficient K of the coarse-grained stratum; S2: calculating the flow rate q of the calcium-based clay mineral-sodium silicate mixed slurry per unit time according to the volume Vs of the soil cut by the cutter head of the shield machine per unit time and the injection ratio KIR. S3: calculating the flow rate q of the calcium-based clay mineral slurry per unit time in the individual mixing vessel (1) according to the preset volume ratio M of the calcium-based clay mineral slurry and the sodium silicate solution, the number N of the mixing vessels (1), and the flow rate q of the calcium-based clay mineral-sodium silicate mixed slurry per unit time K , and the flow rate q of the sodium silicate solution per unit time in the individual mixing vessel (1) G ; the mixing vessel (1) is used to mix the calcium-based clay mineral slurry input by the first raw material bin (2) and the sodium silicate solution input by the second raw material bin (3); S4: start the shield machine, the pumping device (4) pumps the calcium-based clay mineral slurry and the sodium silicate solution into the mixing container (1) according to the flow rate q of the calcium-based clay mineral slurry per unit time K and the flow rate q of the sodium silicate solution per unit time G At the same time, the calcium-based clay mineral slurry in the first raw material bin (2) and the sodium silicate solution in the second raw material bin (3) are pumped into the mixing container (1) to form a calcium-based clay mineral-sodium silicate mixed slurry, and the calcium-based clay mineral-sodium silicate mixed slurry is injected into the soil bin (5) of the shield machine to mix with the shield spoil.

2. The method of improving a shield muck of a water-rich coarse-grained formation according to claim 1, characterized in that, Before S1, the method further comprises: adding calcium-based clay mineral powder and water into the first raw material bin (2) according to a preset mass ratio of water to calcium-based clay mineral powder; stirring the calcium-based clay mineral powder and water in the first raw material bin (2) until a calcium-based clay mineral slurry is formed; adding a sodium silicate solution into the second raw material bin (3).

3. The method of improving a shield muck of a water-rich coarse-grained formation according to claim 2, characterized in that, After S4, the method further comprises: S5: performing a slump test on the mixture of the calcium-based clay mineral-sodium silicate mixed slurry and the shield muck taken from the belt conveyor of the shield machine every preset time period, and adjusting the injection ratio KIR according to the slump value so that the slump value is greater than or equal to 15 cm and less than or equal to 20 cm.

4. The method of improving a shield muck of a water-rich coarse-grained formation according to claim 3, characterized in that, The adjusting of the injection ratio KIR according to the slump value so that the slump value is greater than or equal to 15 cm and less than or equal to 20 cm comprises: if the slump value is less than 15 cm, increasing the injection ratio KIR by 5% and repeating S2-S5 until the slump value is greater than or equal to 15 cm and less than or equal to 20 cm; if the slump value is greater than 20 cm, decreasing the injection ratio KIR by 5% and repeating S2-S5 until the slump value is greater than or equal to 15 cm and less than or equal to 20 cm.

5. The method of improving a shield muck of a water-rich coarse-grained formation according to claim 2, characterized in that, The preset mass ratio of water to calcium-based clay mineral powder is 3:

1.

6. The method of improving a shield muck of a water-rich coarse-grained formation according to claim 1, characterized in that, The preset volume ratio M of the calcium-based clay mineral slurry to the sodium silicate solution is 10:1 to 7:

1.

7. The method of improving a shield muck of a water-rich coarse-grained formation according to claim 1, characterized in that, The injection ratio KIR is 10% to 20%.

8. The method of improving a shield muck of a water-rich coarse-grained formation according to claim 1, characterized in that, The number N of the mixing containers (1) is 1 to 4.

9. The method of improving a shield muck of a water-rich coarse-grained formation according to claim 3, characterized in that, The preset time period is 1 to 5 minutes.

10. The method of improving a shield muck of a water-rich coarse-grained formation according to claim 1, characterized in that, The pumping pressure of the calcium-based clay mineral slurry in the first raw material bin (2) and the sodium silicate solution in the second raw material bin (3) into the mixing container (1) is equal, and is greater than the pressure inside the soil bin (5) of the shield machine.

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