Low-pressure water-rich tunnel systematic full-face grouting water plugging construction method

Abstract

This invention discloses a systematic full-section grouting and water-blocking construction method for low-pressure water-rich tunnels, comprising the following steps: S10. During TBM excavation, the seepage point in the tunnel is determined to be a segmented, non-high-pressure, water-rich runoff-seepage mixed field; S20. The TBM continues to advance and passes the seepage point; S30. Multiple grouting holes and drainage holes are drilled circumferentially at each longitudinally spaced section of the tunnel seepage point for full-seal grouting operation; S40. After the grouting and water-blocking of each section is completed, the grouting holes and drainage holes of each section are observed to check and analyze the grouting and water-blocking effect. This construction method, through the full-seal grouting operation at the seepage point, drives the grout to diffuse and fill the micro-cracks in the surrounding rock, sealing the runoff-seepage path, thereby improving the water-tightness of the surrounding rock and changing the distribution of the runoff-seepage mixed field. It can quickly and effectively seal the seepage during TBM excavation, with minimal impact on TBM excavation, and is convenient and fast for on-site construction.

Description

Technical Field

[0001] This invention relates to the field of tunnel water plugging technology, and in particular provides a systematic full-section grouting water plugging construction method for low-pressure water-rich tunnels. Background Technology

[0002] my country has numerous mountains and rivers, and the geological conditions encountered during TBM construction are complex and varied. As the TBM reveals (traverses) water-rich fissures, the amount of water leaking (seeping, gushing) inside the tunnel increases non-linearly, posing a great risk to the safety of personnel and the TBM tunneling machine, and seriously affecting the construction.

[0003] When tunnels traverse water-rich and fractured strata, groundwater leakage can occur. To ensure construction safety and convenience, groundwater treatment is necessary, with the main approaches being drainage and water blocking. Water blocking or drainage through structural means can effectively reduce water pressure, but excessive drainage can damage the ecosystem. Focusing on the low-pressure, water-rich area of ​​the tunnel, addressing the issue of excessive leakage, using a localized, single-point polyurethane foam grouting method only alters the water outlet path; the leakage volume remains largely unchanged.

[0004] Furthermore, there is currently no suitable water-stopping method for segmented, non-high-pressure, water-rich, mixed-flow fields with long distances, leading to significant arbitrariness in construction and resulting in low efficiency and poor effectiveness. Therefore, it is crucial to study a full-section grouting method for water-stopping in segmented, low-pressure, water-rich fractured formations during TBM construction. This method is of great significance for effectively and quickly handling sudden water inrushes during TBM construction while ensuring construction safety. Summary of the Invention

[0005] Based on this, the present invention provides a systematic full-section grouting and water-blocking construction method for low-pressure water-rich tunnels, so as to standardize the water-blocking construction at tunnels in segmented non-high-pressure water-rich seepage mixed fields and improve water-blocking efficiency and effect.

[0006] To achieve the above objectives, the technical solution of this invention is: a systematic full-section grouting and water-blocking construction method for low-pressure water-rich tunnels, used to quickly and effectively seal seepage water during TBM excavation, comprising the following steps:

[0007] S10. During the TBM excavation process, it was determined that the seepage point in the tunnel was a segmented non-high-pressure water-rich channel-seepage mixed field;

[0008] S20. After the seepage occurred, the water was drained until the water level inside the tunnel dropped, and the TBM continued to move forward and passed the seepage point;

[0009] S30. At each longitudinally spaced section of the tunnel seepage point, drill multiple grouting holes and drainage holes circumferentially. The grouting holes include sequence I holes and sequence II holes arranged circumferentially. The diameter of the sequence I holes is larger than that of the sequence II holes, and the depth of the sequence I holes is greater than that of the sequence II holes. The drainage holes are located below the horizontal radial line. Grouting is performed to completely seal the seepage point using grout according to the following steps:

[0010] S301. Grouting and water plugging shall be carried out in the I-sequence holes and II-sequence holes of the tunnel top and sidewalls respectively, and grouting shall not be carried out at the ventilation duct location for the time being;

[0011] S302. Grout and plug the water in the I-sequence holes and II-sequence holes of the base plate respectively, until all grouting holes are completely sealed;

[0012] S303. Perform additional grouting and water plugging on the remaining ungrouted areas, such as the ventilation duct and the TBM's rear supporting facilities.

[0013] The grouting sequence is as follows: longitudinally from both ends to the middle, and radially from top to bottom. For each section, the first sequence hole is grouted first, followed by the second sequence hole. Grouting is carried out from top to bottom in the same section, and the grouting pressure of the second sequence hole is greater than that of the first sequence hole. Grouting ends when the grouting section stops grouting under the maximum test design pressure.

[0014] S40. After the grouting and water plugging of each section is completed, observe the grouting holes and drainage holes of each section, and check and analyze the grouting and water plugging effect.

[0015] Optionally, during the grouting process at a cross-section, the grouting of each sequence I hole is completed from top to bottom, followed by the grouting of sequence II holes from top to bottom. In the process of completing the sequence I hole grouting, the grouting of the top sequence I holes is completed first, followed by the grouting of the sequence I holes on both sides symmetrically, and finally the grouting of the sequence I holes in the bottom plate is completed. Then, the grouting of each sequence II hole is completed from top to bottom, followed by the grouting of sequence II holes from top to bottom. In the process of completing the sequence II hole grouting, the grouting of the top sequence II holes is completed first, followed by the grouting of the sequence II holes on both sides symmetrically, and finally the grouting of the sequence II holes in the bottom plate is completed.

[0016] Optionally, after drilling each sequence I hole and each sequence II hole, a one-way valve is connected to the outer end of each sequence I hole and each sequence II hole. The one-way valve only allows liquid to flow from the outside to the inside and prohibits liquid from flowing from the inside to the outside. After grouting, once the grout in the hole has solidified, each one-way valve is removed.

[0017] Optionally, when the grouting section has a large injection volume and is difficult to end, at least one of the following measures may be used: flow restriction, pressure restriction, volume restriction, intermittent grouting, or grouting.

[0018] Optionally, when multiple adjacent grouting holes are connected in a cross-flow, grouting can be synchronously injected into the adjacent grouting holes using grouting equipment, or the grouting plug valve in the connecting hole can be sealed.

[0019] Optionally, the length of the grouting section, the grouting pressure, the grouting concentration, or whether to add a quick-setting agent can be determined based on the seepage pressure and seepage volume before grouting.

[0020] Optionally, the slurry is a composition of cement slurry and water glass, with a mixing ratio of water glass Baume degree 30Be′, water-cement ratio of 0.6 to 0.7:1, volume ratio of cement slurry to water glass of 1:1, and slurry setting time of 30s.

[0021] Optionally, based on the presence of fracture structures, the amount of seepage water, and the presence of a mixed state of seepage field and runoff field at the seepage point in the tunnel, it can be determined whether the seepage point in the tunnel is a segmented non-high-pressure water-rich runoff-seepage mixed field.

[0022] Optionally, during the TBM excavation process, the fracture structure of the tunnel and the state of seepage water are observed. When the seepage water volume continues to increase and there are seepage field and runoff field conditions, it is determined to be a segmented non-high pressure water-rich runoff-seepage mixed field.

[0023] Preferably, before and after the completion of S301 grouting, the seepage volume a1 before grouting and sealing, the seepage volume a2 after grouting and sealing, and the seepage status are monitored and compared.

[0024] Before and after the completion of S302 grouting, monitor and compare the seepage water volume a2 before grouting, the seepage water volume a3 after grouting, and the seepage water area until the local dripping and a small amount of linear water flow become local dripping and seepage within the ventilation duct area.

[0025] Before and after the completion of S303 grouting, grouting was carried out intermittently in some special parts, and the seepage water volume a3 before grouting and the seepage water volume a4 after grouting were monitored and compared until there was no more seepage water after grouting.

[0026] Compared with existing tunnel construction water plugging methods, the technical advantages of the systematic full-section grouting water plugging construction method for low-pressure water-rich tunnels provided by this invention are mainly reflected in:

[0027] Firstly, the systematic full-section grouting and water-blocking construction method of the present invention, targeting the characteristics of segmented non-high-pressure water-rich seepage mixed fields, drills multiple grouting holes and drainage holes circumferentially at each section along longitudinal intervals at the seepage point. The grouting holes include sequence I holes and sequence II holes arranged circumferentially at intervals. The drainage holes are set below the horizontal radial line. Grout is used to grout and block water according to the sequence I holes and sequence II holes of the top, side walls and bottom walls. Then, for the remaining ungrouted parts such as the ventilation duct and the TBM-related parts, the grouting sequence is from both ends to the middle longitudinally and from top to bottom radially, realizing the grouting and water-blocking sequence of "high position first, then low position" and "both ends first, then middle", so that the grouting and water-blocking is orderly and efficient, convenient for on-site construction, and achieves a better water-blocking effect.

[0028] Secondly, the diameter of the drilled first-order holes is larger than that of the second-order holes, and the depth of the first-order holes is greater than that of the second-order holes. The first-order holes are grouted first, followed by the second-order holes, and the grouting is carried out from top to bottom in the same section. Furthermore, the grouting pressure of the second-order holes is greater than that of the first-order holes. This achieves the goal of first completing the water plugging at low pressure and high discharge, first completing the water plugging of deep structures, then completing the water plugging at high pressure and low discharge, and finally completing the water plugging of shallow structures. This reflects the principle of grouting and water plugging of "deep layers and high discharge" first, and then "shallow layers and low discharge", which facilitates on-site construction and achieves better water plugging effect. The water plugging structure formed by grouting and water plugging at different depths has strong stability and the water plugging effect is long-lasting and effective. Attached Figure Description

[0029] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments. The accompanying drawings, which are included to provide a further understanding of the invention and constitute a part of this application, illustrate exemplary embodiments of the invention and, together with their descriptions, serve to explain the invention and do not constitute an undue limitation thereof.

[0030] Figure 1 This is a schematic diagram of the process for the systematic full-section grouting and water plugging construction method for low-pressure water-rich tunnels.

[0031] Figure 2 The layout diagram of the grouting holes and drainage holes at the provided cross-section.

[0032] Figure 3 This is a schematic diagram of the process for grouting to completely seal the seepage points using the provided grouting material.

[0033] Figure 4 A schematic diagram illustrating the process of simultaneously conducting water-blocking construction and observing the grouting effect. Detailed Implementation

[0034] In grouting and water plugging construction in low-pressure, water-rich areas of tunnels, the currently used local single-point polyurethane foam grouting method can only change the water outlet path, without significantly altering the water discharge volume. Furthermore, there is currently no suitable water plugging method for long-distance, segmented, non-high-pressure, water-rich seepage-mixed fields, leading to significant arbitrariness in construction and resulting in low efficiency and poor effectiveness.

[0035] To address the aforementioned technical problems, this invention provides a systematic full-section grouting method for water plugging in low-pressure water-rich tunnels, which standardizes water plugging construction in segmented, non-high-pressure water-rich seepage mixed fields, thereby improving water plugging efficiency and effectiveness.

[0036] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. Unless otherwise specifically stated, the relative arrangement of the components and steps set forth in these embodiments does not limit the scope of the present invention.

[0037] like Figure 1 As shown, the present invention provides a systematic full-section grouting and water-blocking construction method for low-pressure water-rich tunnels, used to quickly and effectively seal seepage water during TBM excavation, including the following steps:

[0038] S10. During TBM excavation, the seepage point within the tunnel is determined to be a segmented, non-high-pressure, water-rich runoff-seepage mixed field. In specific implementations, preferably, the determination of whether the seepage point within the tunnel is a segmented, non-high-pressure, water-rich runoff-seepage mixed field is based on the presence of fracture structures, the amount of seepage water, and the presence of a mixed state of seepage and runoff fields. In some preferred embodiments, during TBM excavation, the fracture structures of the tunnel and the state of the seepage water are observed. When the amount of seepage water continuously increases, and a seepage field and a runoff field are present, it is determined to be a segmented, non-high-pressure, water-rich runoff-seepage mixed field.

[0039] S20. After seepage occurs, the water level inside the tunnel is lowered, and the TBM continues to move forward and passes the seepage point. In this way, it is not necessary to move the TBM back and forth along the tunnel, which facilitates the rapid entry of water-blocking equipment and helps to improve the construction speed.

[0040] S30. At each longitudinally spaced section of the tunnel at the seepage point, drill multiple grouting holes and drainage holes circumferentially, such as... Figure 2 As shown, the grouting holes include sequence I holes and sequence II holes arranged circumferentially. The diameter of the sequence I holes is larger than that of the sequence II holes, and the depth of the sequence I holes is greater than that of the sequence II holes. The drainage holes are located below the horizontal radial line. The grout is a combination of cement slurry and water glass, with a mixing ratio of water glass Baumé degree 30Be′, water-cement ratio 0.6-0.7:1, cement slurry to water glass volume ratio 1:1, and grout setting time 30s. Figure 3 As shown, the grouting operation for completely sealing the seepage points was carried out using grouting material following these steps:

[0041] S301. Grouting and water plugging shall be carried out in the I-sequence holes and II-sequence holes of the tunnel top and sidewalls respectively, and grouting shall not be carried out at the ventilation duct location for the time being;

[0042] S302. Grout and plug the water in the I-sequence holes and II-sequence holes of the base plate respectively, until all grouting holes are completely sealed;

[0043] S303. Perform additional grouting and water plugging on the remaining ungrouted areas, such as the ventilation duct and the TBM's rear supporting facilities.

[0044] The grouting sequence is as follows: longitudinally from both ends to the middle, and radially from top to bottom. For each section, the first sequence hole is grouted first, followed by the second sequence hole. Grouting is carried out from top to bottom in the same section, and the grouting pressure of the second sequence hole is greater than that of the first sequence hole. Grouting ends when the grouting section stops grouting under the maximum test design pressure.

[0045] Preferably, during the grouting process at a cross-section, the grouting of each sequence I hole is completed from top to bottom, followed by the grouting of sequence II holes from top to bottom. In the process of completing the sequence I hole grouting, the top sequence I holes are grouted first, followed by the sequence I holes on both sides symmetrically, and finally the sequence I holes of the bottom plate are grouted. Then, the grouting of each sequence II hole is completed from top to bottom, followed by the grouting of sequence II holes from top to bottom. In the process of completing the sequence II hole grouting, the top sequence II holes are grouted first, followed by the sequence II holes on both sides symmetrically, and finally the sequence II holes of the bottom plate are grouted.

[0046] Preferably, after drilling each sequence I hole and each sequence II hole, a one-way valve is connected to the outer end of each sequence I hole and each sequence II hole. The one-way valve only allows liquid to flow from the outside to the inside and prohibits liquid from flowing from the inside to the outside. After grouting, once the grout in the hole has solidified, each one-way valve is removed.

[0047] During grouting construction, the following measures are preferred: When the grouting section has a large injection volume and is difficult to terminate, at least one of the following measures should be used: flow restriction, pressure restriction, volume restriction, intermittent grouting, or grouting in general. When grout flows through multiple adjacent grouting holes, grout should be injected synchronously into the adjacent grouting holes using grouting equipment, or the grouting plug valve in the connecting hole should be sealed. The length of the grouting section, grouting pressure, grouting concentration, or whether to add a quick-setting agent should be determined based on the seepage water pressure and seepage volume before grouting.

[0048] S40. After grouting and water plugging are completed at each section, observe the grouting holes and drainage holes at each section to check and analyze the grouting and water plugging effect. For example... Figure 4 As shown, in some preferred embodiments, before and after grouting in step S301, the seepage volume a1 before grouting and the seepage volume a2 after grouting and the seepage status are monitored and compared; before and after grouting in step S302, the seepage volume a2 before grouting and the seepage volume a3 after grouting and the seepage area are monitored and compared until local dripping and a small amount of linear water flow become local dripping and seepage within the ventilation duct; before and after grouting in step S303, grouting is intermittently performed on some special parts, and the seepage volume a3 before grouting and the seepage volume a4 after grouting are monitored and compared until there is no more seepage after grouting. By observing the seepage volume and seepage status while plugging the water, and determining the subsequent implementation of the water plugging construction based on the observed phenomena, the water plugging process is orderly and traceable, effectively improving the efficiency of water plugging construction.

[0049] The following is a specific implementation example from a construction site. The provided method for systematic full-section grouting and water plugging treatment of low-pressure water-rich tunnels includes the following steps:

[0050] (1) During the tunneling process, after the TBM passes through the fractured strata or below the river, linear or strand-shaped seepage water appears at some points in the tunnel. According to the exposed conditions of the tunnel section, there are two fracture structures in the tunnel: F40: fault of unknown nature and Fx: inferred reverse fault, mainly the Hurige Formation of the Middle Jurassic. This section is a strongly weathered layer with well-developed joints and fractures.

[0051] (2) During the TBM's tunneling process, large-area linear water flow and stream-like water inrush occurred, with the inflow volume continuously increasing to 39,000 m³. 3 / day. The flow is primarily a seepage field, with some runoff present. In the section passing beneath the river, tunnel fissures connect with the surface river, providing water replenishment and resulting in large-area linear flow and confined watercourses, constituting a runoff field. It is determined to be a segmented, non-high-pressure, water-rich runoff-seepage mixed field.

[0052] (3) After seepage water occurs, continuing to excavate poses a significant risk of machine flooding and construction safety risks. However, since the TBM cannot provide a water-blocking working face due to obstruction, drainage operations are organized first. When the water level in the tunnel decreases, the TBM continues to advance and performs water-blocking operations after passing the sudden water inrush point.

[0053] Furthermore, step 2) includes the following steps:

[0054] (1) Grouting can fill the micro-cracks in the surrounding rock through grout diffusion, block the seepage path, improve the physical and mechanical properties of the surrounding rock, fully improve and utilize the water-proof properties of the surrounding rock, change the distribution of the seepage-runoff mixing field after tunnel excavation, reduce the discharge volume, and achieve the purpose of plugging leakage and preventing seepage.

[0055] (2) Grouting materials generally include cement grouting materials, chemical grouting materials, and composite grouting materials. Cement grouting materials are widely available and easy to apply, but their stability is poor. Water glass-based materials have low viscosity and good injectability, but their setting time is unstable. Polyurethane-based materials have small particle size, but their strength is low. Two-component grout (cement grout + water glass) is currently a commonly used material, overcoming the disadvantages of cement grout such as long setting time and susceptibility to erosion, and providing good grouting effect.

[0056] Furthermore, step 3) includes the following steps:

[0057] Each cross-section is equipped with 14-15 grouting holes, spaced 2m apart, with a hole depth of 3m, arranged in a grid pattern. Three drainage holes, 3.5m deep, are drilled along the waistline on both sides of each cross-section and in the middle of the bottom plate. Plastic ball valves are installed at the hole openings in the bottom plate. The diameter of the grouting holes is Φ≥42mm. The drilling direction must be accurate, with a hole bottom deviation not exceeding 8cm. Drilling of the grouting holes is carried out in sections and sequences according to the grouting procedure. If hole collapse occurs during drilling, a handheld twist drill should be used. The hole openings are protected with plugs while waiting for grouting or after grouting is completed.

[0058] Furthermore, step 4) includes the following steps:

[0059] (1) Two-component grouting material is used, with the mix proportion parameters controlled as follows: water glass Baume degree 30Be′, water-cement ratio 0.6~0.7:1 (P·42.5 silicate cement). During grouting, the volume ratio of cement grout to water glass is 1:1, the grout setting time is adjusted to 30s, and the weighing error of the grouting material is less than 5%. The grout mixing equipment uses a ZJ-400 high-speed mixer for grout preparation. Following the method for preparing single-component cement grout, water is added first, followed by the other materials for mixing; the grout must be stirred evenly and the grout concentration must be measured. After a long pause in grouting, all equipment and conveying pipelines should be thoroughly cleaned before resuming grouting.

[0060] (2) "Systematic full-section grouting and water plugging" refers to the water plugging operation using a combination of two-component grout (cement grout + water glass) grouting and single-point polyurethane foam supplementary grouting. Two-component grout is used to "sweep the holes" in a timely manner before implementing L·SAC (low-alkali sulfoaluminate rapid-hardening cement) single-component grouting for water plugging. The grouting principle is "grooving from both ends towards the middle longitudinally, and from top to bottom radially, first with pressureless sealing followed by concentrated sealing."

[0061] (3) During the grouting process, the setting time of the grout should be observed at all times to prevent the grout from solidifying and clogging the pump pipe. The grouting pressure is 0.5-1 MPa, the grouting pressure of the first sequence hole is 0.5 MPa, and the grouting pressure of the second sequence hole is 0.8-1.0 MPa. The grouting should proceed from both ends to the middle. For each section, the first sequence hole should be grouted first, followed by the second sequence hole, and the grouting should proceed from top to bottom within the same section. Grouting can be stopped when the grouting section stops injecting grout under the maximum test design pressure. After the grouting achieves the expected effect, the shotcrete and anchoring construction should be organized immediately to seal the grouting rock surface.

[0062] (4) Special Case Handling: If grout cross-contamination occurs in several holes, and the cross-contamination holes are ready for grouting, grouting can be carried out simultaneously. Otherwise, the grouting plug valve in the connecting hole should be closed. Grouting must be continuous. If it is interrupted for any reason, grouting should be resumed as soon as possible. Otherwise, depending on the actual situation, the borehole should be flushed or swept before grouting can be resumed. The pressure for resuming grouting can be the value before the interruption. For grouting holes with water inflow at the borehole opening, the water inflow pressure and water inflow volume should be recorded before grouting. Depending on the water inflow situation, the grouting section length can be shortened, the grouting pressure can be increased, and thick grout can be injected. Depending on the actual situation, an appropriate amount of quick-setting agent can be added to the grout. If the injection volume of the outer grouting section is large and it is difficult to finish grouting, measures such as flow restriction, pressure restriction, volume restriction, and intermittent grouting should be adopted for grouting.

[0063] Furthermore, step 5) includes the following steps:

[0064] (1) During the grouting process, due to the TBM itself, the obstruction of the ventilation duct at the top of the tunnel, and the water accumulation at the bottom of the tunnel, the full sealing grouting is mainly divided into three stages to eliminate infection:

[0065] Phase 1 (Grouting of the top and sidewalls): Grouting will be carried out on the top and sidewalls of the tunnel to reduce water leakage. Grouting will not be carried out at the ventilation duct location for the time being, and will be completed in Phase 3.

[0066] Second stage (bottom slab grouting - completion of full sealing): After the first stage of grouting is completed, the drainage volume decreases, the water accumulation is reduced, and the grouting construction is facilitated;

[0067] The third stage ("point-to-point" supplementary grouting): non-shrink single-liquid cement grout is used to supplement the grouting of the remaining ungrouted areas, such as the ventilation duct and the TBM rear-mounted equipment.

[0068] (2) Effect Analysis: After the first stage of grouting was completed, the on-site drainage volume was monitored, and the daily drainage volume decreased from the initial 39,000 m³ to 19,500 m³. The original streams of water and large-area linear flow changed to localized dripping and small amounts of linear flow. After the second stage of grouting was completed, the daily drainage volume decreased from 19,500 m³. 3 Reduced to 13200m 3 The water flow changed from localized dripping and small linear flows to localized dripping and seepage within the ventilation duct area. The third stage, a "point-to-point" supplementary grouting and water-stopping phase, was affected by TBM construction, resulting in intermittent grouting of certain special areas. The total grouting volume decreased from 13200 m³ to 11500 m³. 3 (For drainage of other tunnel sections), the tunnel has basically achieved a watertight effect.

[0069] By employing the above-mentioned technical solution, this invention has the advantages of rapid, convenient, easy-to-operate, and highly safe construction. The "systematic full-section grouting and water-blocking" method can effectively and promptly seal water-rich tunnels, ensuring the safety of TBM excavation and construction personnel. It also improves rock integrity, limits drainage volume, and reduces the risk of TBM downtime due to water inrush during subsequent excavation. This improves construction efficiency, shortens construction time, and reduces construction costs.

[0070] The above methods achieved the following results: First, full-sealing grouting effectively improves the funnel effect of water leakage, resulting in a good water-blocking effect. Second, for water-blocking tunnels (sections) in low-pressure, water-rich, fractured strata, the use of systematic full-sealing grouting can drastically reduce the leakage volume, achieving a state of localized dripping or even no leakage, with excellent results. Third, full-sealing grouting for water-rich tunnels (sections) avoids ecological damage caused by the drop in water levels around the tunnel, which is worthy of research and promotion.

[0071] The present invention provides a systematic full-section grouting and water-blocking construction method for low-pressure water-rich tunnels, which standardizes water-blocking construction in segmented, non-high-pressure water-rich tunnels with seepage-flow mixing fields, thereby improving water-blocking efficiency and effectiveness.

[0072] Specifically as follows:

[0073] Firstly, considering the characteristics of the segmented non-high-pressure water-rich seepage mixed field, multiple grouting holes and drainage holes are drilled circumferentially at each cross section along the longitudinal interval at the seepage point. The grouting sequence is longitudinal from both ends to the middle and radial from top to bottom, realizing the grouting and water blocking sequence of "high position first, then low position" and "both ends first, then middle". This makes the grouting and water blocking orderly, fast and efficient, convenient for on-site construction, and achieves a good water blocking effect.

[0074] Secondly, the method achieves water plugging in the low-pressure, high-volume areas first, followed by the deep structure, then the high-pressure, low-volume areas, and finally the shallow structure. This reflects the principle of grouting water plugging in the "deep, high-volume" first, followed by the "shallow, low-volume" second. This facilitates on-site construction, achieves better water plugging results, and the water plugging structure formed by grouting at different depths has strong stability and a long-lasting and effective water plugging effect.

[0075] Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this invention. The above drawings and specific embodiments are for illustrative purposes only, and this invention is not limited thereto. Minor modifications to this invention within the inventive spirit and scope defined by the claims of this invention all fall within the protection scope of this invention.

Claims

1. A systematic full-section grouting and water-blocking construction method for low-pressure, water-rich tunnels, used for rapidly and effectively sealing seepage water during TBM excavation, characterized in that... Including the following steps: S10. During the TBM excavation process, it was determined that the seepage point in the tunnel was a segmented, non-high-pressure, water-rich, mixed seepage field. S20. After the seepage occurred, the water was drained until the water level inside the tunnel dropped, and the TBM continued to move forward and passed the seepage point; S30. At each longitudinally spaced section of the tunnel seepage point, drill multiple grouting holes and drainage holes circumferentially. The grouting holes include sequence I holes and sequence II holes arranged circumferentially. The diameter of the sequence I holes is larger than that of the sequence II holes, and the depth of the sequence I holes is greater than that of the sequence II holes. The drainage holes are located below the horizontal radial line. Grouting is performed to completely seal the seepage point using grout according to the following steps: S301. Grouting and water plugging shall be carried out in the I-sequence holes and II-sequence holes of the tunnel top and sidewalls respectively, and grouting shall not be carried out at the ventilation duct location for the time being; S302. Grout and plug the water in the I-sequence holes and II-sequence holes of the base plate respectively, until all grouting holes are completely sealed; S303. Supplement grouting and water plugging in the remaining ungrouted areas; The grouting sequence is as follows: longitudinally from both ends to the middle, and radially from top to bottom. For each section, the first sequence hole is grouted first, followed by the second sequence hole. Grouting is carried out from top to bottom in the same section, and the grouting pressure of the second sequence hole is greater than that of the first sequence hole. Grouting ends when the grouting section stops grouting under the maximum test design pressure. S40. After the grouting and water plugging of each section is completed, observe the grouting holes and drainage holes of each section, and check and analyze the grouting and water plugging effect.

2. The method for systematic full-section grouting and water plugging construction of low-pressure water-rich tunnels according to claim 1, characterized in that: During the grouting process at a cross-section, the grouting of each sequence I hole is completed from top to bottom, followed by the grouting of sequence II holes from top to bottom. In the process of completing the grouting of sequence I holes, the grouting of the sequence I holes at the top is completed first, followed by the grouting of the sequence I holes on both sides symmetrically, and finally the grouting of the sequence I holes in the bottom plate is completed. Then, the grouting of each sequence II hole is completed from top to bottom, followed by the grouting of sequence II holes from top to bottom. In the process of completing the grouting of sequence II holes, the grouting of the sequence II holes at the top is completed first, followed by the grouting of the sequence II holes on both sides symmetrically, and finally the grouting of the sequence II holes in the bottom plate is completed.

3. The systematic full-section grouting and water-blocking construction method for low-pressure water-rich tunnels according to claim 1 or 2, characterized in that: After drilling each sequence I hole and each sequence II hole, connect a one-way valve to the outer end of each sequence I hole and each sequence II hole. The one-way valve only allows liquid to flow from the outside to the inside and prohibits liquid from flowing from the inside to the outside. After grouting, wait for the grout in the hole to solidify and then remove each one-way valve.

4. The systematic full-section grouting and water-blocking construction method for low-pressure water-rich tunnels according to claim 1 or 2, characterized in that: When the grouting section has a large injection volume and is difficult to end, at least one of the following measures should be used: flow restriction, pressure restriction, volume restriction, intermittent grouting, or grouting.

5. The systematic full-section grouting and water-blocking construction method for low-pressure water-rich tunnels according to claim 1 or 2, characterized in that: When grout flows through multiple adjacent grouting holes, grout is injected synchronously into the adjacent grouting holes using grouting equipment, or the grouting plug valve in the connecting hole is sealed.

6. The systematic full-section grouting and water-blocking construction method for low-pressure water-rich tunnels according to claim 1, characterized in that: Based on the seepage pressure and seepage volume before grouting, determine the length of the grouting section, grouting pressure, grouting concentration, or whether to add a quick-setting agent.

7. The method for systematic full-section grouting and water plugging construction of low-pressure water-rich tunnels according to claim 1, characterized in that: The slurry is a combination of cement slurry and water glass, with a mixing ratio of water glass Baume degree 30Be´, water-cement ratio of 0.6 to 0.7:1, cement slurry to water glass volume ratio of 1:1, and slurry setting time of 30s.

8. The method for systematic full-section grouting and water plugging construction of low-pressure water-rich tunnels according to claim 1, characterized in that: Based on the presence of fracture structures, seepage volume, and the presence of a mixed state of seepage and runoff fields at the seepage point inside the tunnel, it is determined whether the seepage point inside the tunnel is a segmented, non-high-pressure, water-rich runoff-seepage mixed field.

9. The systematic full-section grouting and water-blocking construction method for low-pressure water-rich tunnels according to claim 8, characterized in that: During TBM excavation, the fracture structure and seepage water status of the tunnel are observed. When the seepage water volume continues to increase and there are seepage and runoff fields, it is determined to be a segmented non-high-pressure water-rich runoff-seepage mixed field.

10. The method for systematic full-section grouting and water plugging construction of low-pressure water-rich tunnels according to claim 1, characterized in that: Before and after the completion of S301 grouting, the seepage volume a1 before grouting and the seepage volume a2 after grouting and the seepage status were monitored and compared. Before and after the completion of S302 grouting, monitor and compare the seepage water volume a2 before grouting, the seepage water volume a3 after grouting, and the seepage water area until the local dripping and a small amount of linear water flow become local dripping and seepage within the ventilation duct area. Before and after the completion of S303 grouting, grouting was carried out intermittently in some special parts, and the seepage water volume a3 before grouting and the seepage water volume a4 after grouting were monitored and compared until there was no more seepage water after grouting.

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