A method for treating seepage water of a high-cold region mountain-adjacent traffic tunnel during operation period

Abstract

The application is suitable for the technical field of tunnel and underground engineering leakage water treatment, and provides a high-cold region mountain-adjacent traffic tunnel operation period seepage water treatment method, which comprises the following steps: drilling into the rock above the tunnel from the side slope outside the mountain-adjacent traffic tunnel to form a grouting hole which penetrates from the side slope surface to the rock above the tunnel roof; lowering a steel flower pipe into the grouting hole, the pipe wall of the steel flower pipe is provided with a grout outlet hole, and the flower pipe section of the steel flower pipe corresponds to the surrounding rock within the set range above the tunnel roof; pouring grout into the surrounding rock cracks through the steel flower pipe, and forming an anti-seepage curtain in the rock above the tunnel roof after grouting is completed; constructing a drainage hole above the grouting hole, the drainage hole is drilled from the side slope surface into the rock above the tunnel roof; filling the drainage hole orifice side slope with broken stones and fine-grained soil to form a frost protection cover; the application has the advantages of good treatment effect, strong durability, construction safety, low cost and the like, and is particularly suitable for the treatment of seepage diseases of the built mountain-adjacent traffic tunnel in the high-altitude and high-cold region during the operation period.

Description

Technical Field

[0001] This invention relates to the field of tunnel and underground engineering seepage control technology, specifically a method for controlling seepage during the operation of a mountain-side transportation tunnel in a high-altitude and cold region. Background Technology

[0002] Mountain-side tunnels in high-altitude, cold mountainous areas refer to transportation tunnels built along the mountainside, with one or both sides of the tunnel body adjacent to the mountain slope. These tunnels are widely distributed in the high-altitude regions of western my country and are crucial transportation infrastructure connecting mountainous areas with the outside world. Due to historical reasons and limitations in construction conditions, many mountain-side tunnels lacked systematic waterproof lining structures during construction, leaving the tunnel walls directly exposed to the surrounding rock (i.e., bare rock tunnel walls). Groundwater seeps into the tunnels along fissures in the surrounding rock. In winter in high-altitude, cold regions, the water seeping into the tunnels freezes on the road surface and tunnel walls, causing slippery roads, drastically deteriorating traffic conditions, seriously threatening driving safety, and even causing traffic disruptions. This has become a significant problem restricting the safe operation of transportation infrastructure in high-altitude, cold regions.

[0003] For seepage control in mountain-side tunnels, the following technical solutions are currently mainly used both domestically and internationally. One method is grouting of exposed rock inside the tunnel. This involves drilling holes in the exposed rock walls and injecting cement grout to seal fissures. However, because the exposed rock surface is free, the grout overflows into the tunnel along the fissures, resulting in a very low effective filling rate; the grout utilization rate is typically less than 30%. Furthermore, there are no effective grout-stopping devices at the borehole openings, requiring low-pressure grouting (usually <0.3MPa). This prevents the grout from being injected into micro-fissures less than 0.1mm wide, leading to a small grout diffusion radius (usually <0.5m) and loose overlap between holes, forming a discontinuous "honeycomb"-like water-stopping curtain. Simultaneously, the drastic temperature and humidity changes inside the tunnel cause the grouted rock mass to easily develop fissures under freeze-thaw cycles and vehicle vibrations, reopening the seepage channels. This is a typical example of "treating the symptoms but not the root cause." Conventional lining renovation technology waterproofs the entire tunnel cross-section by adding lining layers and waterproofing membranes. However, the lining layer thickness is typically 30-50cm, and the waterproofing and buffer layers are about 5-10cm, totaling an encroachment of 40-60cm on the cross-section. For traffic tunnels where no space was reserved in the early stages, the clearance height and width after implementation are significantly reduced, which may not meet the requirements of road design specifications for building clearances. Alternatively, the tunnel walls may need to be widened, and blasting or mechanical excavation may severely disturb the surrounding rock, requiring traffic interruption for several weeks to months during construction. Among the technologies of intercepting ditches and drainage tunnels on the tunnel roof, intercepting ditches are suitable for situations where the surface catchment area is clear and the terrain is flat. For traffic tunnels with steep mountain slopes on the roof, construction is difficult and the water interception effect is limited. Moreover, intercepting ditches mainly intercept surface runoff and have little effect on intercepting deep fissure water in the mountain. Drainage tunnels require a large construction cross-section and are very expensive. For existing traffic tunnels, the conditions above the tunnel roof are often not suitable for construction. Blind drain technology inside tunnels collects and drains seepage water by setting up blind drains and drainage ditches inside the tunnel. However, in the low-temperature winter environment of high-altitude and cold regions, blind drains and drainage ditches are prone to freezing and blockage, and the seepage water will eventually overflow onto the road surface and freeze. Moreover, this technology cannot reduce the seepage flow, and is a passive treatment. Surface pre-grouting technology during construction is only applicable to pretreatment before tunnel excavation and cannot be applied to existing operational traffic tunnels. Furthermore, it lacks supporting drainage, antifreeze, and surrounding rock reinforcement structures, and cannot solve the specific problems associated with operation in high-altitude and cold regions.

[0004] Existing technologies are unable to achieve systematic and long-term treatment of seepage from mountain tunnels in high-altitude, cold regions without disrupting traffic or encroaching on the passageway during operation. Therefore, there is an urgent need to provide a method for treating seepage from mountain tunnels in high-altitude, cold regions during operation, in order to overcome the shortcomings in current practical applications. Summary of the Invention

[0005] The purpose of this invention is to provide a method for treating seepage water in mountain tunnels in high-altitude and cold regions during operation, effectively solving the problems mentioned in the background art.

[0006] This invention is implemented as follows: a method for treating seepage water during the operation of a mountain-side transportation tunnel in a high-altitude, cold region, comprising the following steps: Step 1: Drill into the rock mass above the tunnel from the outer slope of the mountain access tunnel to form a grouting hole that runs from the slope surface to the rock mass above the tunnel top; Step 2: Insert a steel perforated pipe into the grouting hole. The pipe wall of the steel perforated pipe has grout outlet holes. The perforated pipe section corresponds to the surrounding rock within a set range above the tunnel top. Step 3: Grout is injected into the fissures of the surrounding rock through the steel pipe. After the grouting is completed, an anti-seepage curtain is formed in the rock mass above the tunnel. Step 4: Construct drainage holes above the grouting holes. The drainage holes are drilled from the slope surface into the rock mass above the tunnel roof. The termination position of the drainage holes is located above the seepage prevention curtain, and the drainage holes are horizontal holes with a slight upward inclination. Step 5: Fill the drainage hole opening and surrounding area with crushed stones and fine soil to form a frost-proof covering for the opening.

[0007] As a further aspect of the present invention: in step one: the termination position of the grouting hole is 2.5 to 3.5 m above the top of the tunnel; The spacing between the grouting holes is 1.5 to 2.5 m, and they are arranged linearly along the tunnel axis. The inclination angle of the grouting hole is 0° to 5°.

[0008] As a further aspect of the present invention: in step two: the perforated section of the steel perforated pipe corresponds to the rock mass within a thickness range of 2.5 to 3.5 m above the top of the tunnel; The steel pipe has grouting holes or longitudinal grooves arranged in a quincunx pattern on its wall.

[0009] As a further aspect of the present invention: in step three: the grouting is carried out according to the principle of sequence, and is carried out in sequence by sequence I holes, sequence II holes, and sequence III holes. The grouting pressure is controlled at 0.5–1 MPa.

[0010] As a further aspect of the present invention: the sequence holes are grouting holes arranged at a first interval to establish a preliminary water-stopping skeleton; The second-order holes are grouting holes arranged densely between the first-order holes to fill the water-stopping blind areas between the initial water-stopping skeleton; The third sequence holes are further densified grouting holes, forming a continuous and dense seepage-proof curtain.

[0011] As a further aspect of the present invention: in step four: the drainage hole is located 1 to 2 meters above the grouting hole; The inclination angle of the drainage hole is 5° to 10°.

[0012] As a further aspect of the present invention: in step five: the particle size of the crushed stone is 5-20 cm; The fine-grained soil is sandy soil; The thickness of the antifreeze cover is 1.5 to 2.5 m.

[0013] As a further aspect of the present invention: In step three: during the grouting process, monitor the grout seepage situation inside the tunnel. When grout seeps out inside the tunnel, reduce the grouting pressure or adjust the grout ratio. After the grout has initially set, increase the pressure and re-grout.

[0014] As a further aspect of the present invention: in step four: a drainage pipe is inserted into the drainage hole.

[0015] As a further aspect of the present invention: In step one: the spacing between grouting holes is adjusted according to the difference in grouting volume of each grouting hole. When the difference in grouting volume between adjacent grouting holes exceeds a set threshold, the hole spacing is increased. When the difference in grouting volume between adjacent grouting holes is less than the set threshold, the hole spacing is increased.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: This method abandons the traditional passive leak-sealing method inside the tunnel, and directly constructs an anti-seepage curtain at the source of seepage, namely the outer slope and the mountain top of the tunnel, to completely cut off the seepage channel. This solves the core defects of existing technologies, such as repeated leakage and only treating the symptoms without addressing the root cause, and the treatment effect is permanent and stable.

[0017] The insertion of steel perforated pipes transforms grouting from a "diffusion" to a "conduit" method, allowing grout to enter the designated area in an orderly and controllable manner through the outlet holes on the pipe wall. The support provided by the perforated pipes to the borehole wall enables high-pressure grouting. Combined with layered and sequential grouting and dynamic pressure control, the grouting effect changes from "uncontrollable" to "precisely controllable," significantly improving the effective utilization rate of the grout. All construction procedures are concentrated on the external slope of the tunnel, eliminating the need for work inside the tunnel, road closures, or traffic disruptions. It does not occupy the tunnel's traffic cross-section, requires no excavation or reconstruction, and allows the traffic tunnel to operate normally during construction, with no traffic loss or safety risks associated with construction inside the tunnel.

[0018] The newly added micro-tilted drainage holes and thick-layer anti-freeze covering structure, the crushed stone-fine soil composite covering is both the insulation layer of the drainage structure and the infiltration channel of water. It uses the physical properties of natural materials to solve the problem of freezing and blockage in winter. It does not rely on external energy, requires no continuous maintenance, has high long-term stability, and achieves stable seepage prevention and drainage throughout the year.

[0019] Simple grouting can only temporarily seal the seepage points and cannot eliminate the seepage force of groundwater. After the water pressure continues to accumulate, new seepage channels will inevitably be found. This invention adds high-level drainage holes on the basis of water sealing, actively guiding groundwater from the non-freezing area to the outside of the slope, eliminating the conditions for seepage into the tunnel from the power source. Through the synergistic effect of grouting to block water and drainage to relieve pressure, the continuous action of groundwater pressure on the anti-seepage curtain is avoided, preventing the curtain from being damaged by water pressure and freeze-thaw, and greatly improving the durability of the treatment structure.

[0020] Compared with the solution of lining and waterproofing after expanding the cross section, the slope drilling and grouting construction site is open, the working conditions are good, and the safety management is easy to achieve; there is no need to interrupt traffic, and the traffic maintenance cost is zero; the materials used in the project are all conventional building materials, which are easy to obtain and the cost is controllable, and the cost can usually be reduced by more than 90%.

[0021] Sequential grouting allows for dynamic adjustment of borehole spacing and grouting parameters based on geological conditions. It is well-suited for rock masses with uneven fracture development. Furthermore, during construction, the grouting pressure and grout mix ratio can be adjusted in real time based on the grout seepage situation inside the tunnel, ensuring reliable treatment results. Attached Figure Description

[0022] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of the grouting hole arrangement of the present invention; Figure 2 This is a schematic diagram of the drainage hole arrangement of the present invention; Figure 3 This is a schematic cross-sectional view of the present invention; Figure 4 This is a schematic longitudinal section of the present invention.

[0024] In the attached diagram: 1-Traffic tunnel, 2-Grouting hole, 3-Drainage hole, 4-Fine-grained soil, 5-Broken stone, 6-Infiltrated water, 7-Isolation cover. Detailed Implementation

[0025] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] This invention provides an integrated treatment method for seepage water in mountainous tunnels in high-altitude and cold regions during operation. This method combines tunnel roof reinforcement, layered grouting for water stoppage, high-level directional drainage, and antifreeze treatment of drainage outlets. All construction procedures are concentrated on the external slope of the tunnel, eliminating the need for work inside the tunnel, thus preventing traffic disruption and encroachment on the passageway. The purpose of this invention is to provide a method for treating seepage water in mountainous tunnels in high-altitude and cold regions during operation, addressing the technical challenges of existing technologies such as the severe impact on traffic safety caused by the freezing of seepage water in winter, the high construction risk and encroachment on the tunnel's internal cross-section by traditional lining waterproofing schemes, and the poor effectiveness and recurrence of grouting for water stoppage in exposed rock within the tunnel.

[0027] Specifically, the present invention includes the following objectives: Objective (1): To provide a method for systematically treating seepage water in mountainous tunnels in high-altitude and cold regions during operation without interrupting traffic within the tunnel or encroaching on the cross-section of the tunnel, thereby fundamentally avoiding the problems of traffic interruption or insufficient clearance caused by construction in traditional treatment schemes.

[0028] Objective (2): To provide a treatment method that can form a continuous, dense and durable long-term water-stop curtain in the rock mass above the top of the tunnel 1. By combining the near-horizontal grouting holes 2 on the slope with steel flower pipe reinforcement and sequential high-pressure grouting, the defects of the existing bare rock grouting in the tunnel, such as limited grouting pressure, serious grout loss, discontinuous water-stop curtain and insufficient durability, can be overcome.

[0029] Objective (3): To provide a system treatment method of "interception and drainage combination", which, while cutting off the main channel for groundwater to seep into the traffic tunnel 1 through the grouting curtain, safely drains the cut-off groundwater to the outside of the hillside through the micro-inclined drainage hole 3 above the tunnel top of the traffic tunnel 1, reduces the water pressure at the tunnel top, and prevents the water-stopping curtain from failing under long-term water pressure.

[0030] Objective (4): To provide a treatment method that can prevent the drainage system from freezing in winter. By covering the opening of the drainage hole 3 with a composite drainage body (i.e., antifreeze cover 7) that has both water permeability and heat insulation properties, the drainage hole 3 can be kept unobstructed in the extreme low temperature environment of high-altitude and cold regions, and the drainage hole 3 can be prevented from becoming blocked and ineffective due to freezing at the outlet.

[0031] Objective (5): To provide a safe, economical and reasonable treatment method with strong adaptability, which makes full use of the natural working conditions of the outer slope of the traffic tunnel 1, with open construction space, simple procedures, no disturbance to the surrounding rock inside the tunnel, and the hole spacing and grouting parameters of the grouting holes 2 can be flexibly adjusted according to the on-site geological conditions and construction effect. It is applicable to the treatment of seepage water in various existing unlined or simply lined traffic tunnels along the mountain.

[0032] To achieve the above objectives, this invention aims to provide a technical solution for treating seepage water during operation in mountain tunnels in high-altitude and cold regions, characterized by zero traffic interference, zero cross-sectional encroachment, long-term water stoppage, drainage and frost prevention, and safe construction. The following detailed description of the core structures and their interrelationships, in conjunction with specific embodiments, provides a comprehensive overview.

[0033] Example 1: Please refer to Figures 1-4 This embodiment uses a seepage control project of a mountain tunnel in a high-altitude, cold region as an example. The tunnel is located in a high-altitude, cold mountainous area where winter temperatures are low, resulting in severe water seepage and icy road surfaces, seriously affecting traffic safety. The tunnel has unlined bare rock walls, with the mountain above the tunnel ceiling.

[0034] The method for treating seepage water during the operation of mountain tunnels in high-altitude and cold regions, as described in this embodiment, is implemented according to the following steps: (I) Site survey and design First, on-site engineering geological survey and hydrogeological investigation were conducted to determine the lithology, degree of fissure development, groundwater occurrence status and seepage path of the overlying rock mass of the traffic tunnel 1.

[0035] Based on the survey results, the treatment design is as follows: Grouting holes 2 are arranged on the slope along the tunnel axis. The preferred termination position of grouting holes 2 is 3m above the tunnel top, which can be adjusted within the range of 2.5 to 3.5m according to geological conditions. The preferred hole spacing is 2m, which can be adjusted within the range of 1.5 to 2.5m according to geological conditions. Drainage holes 3 are arranged 1 to 2m above the grouting holes 2. The preferred inclination angle of drainage holes 3 is 8°, which can be adjusted within the range of 5° to 10° according to geological conditions. The hole spacing corresponds to that of the grouting holes.

[0036] (ii) Directional drilling of slope A drilling platform was selected on the outer slope of Tunnel 1, and a geological drilling rig was used to drill into the rock mass above the tunnel in a near-horizontal direction. The borehole trajectory was basically horizontal, with an inclination angle of 3°, which could be adjusted within the range of 0° to 5° during actual construction according to terrain conditions. The drilling depth was precisely controlled by surveying and setting out lines to ensure that the bottom of the hole terminated 3m above the tunnel top. After drilling was completed, high-pressure air was used to clean the hole to ensure that there was no rock cuttings blocking it.

[0037] (iii) Insert the steel flower tube The steel perforated pipe is inserted into grouting hole 2. The steel perforated pipe is made of steel tubing with grouting holes arranged in a quincunx pattern on its wall. The hole diameter and groove width are determined based on the particle size of the grouting material, allowing for smooth grout flow while preventing rock cuttings from clogging the hole. The outer diameter of the perforated pipe is slightly smaller than the borehole diameter for easier insertion. The length of the perforated pipe section corresponds to a 3m thick layer of rock mass above the tunnel ceiling; in practice, this can be adjusted within the range of 2.5 to 3.5m depending on geological conditions. After the steel perforated pipe is inserted, a grouting water pressure plug is installed at the borehole opening to prevent grout from overflowing during grouting.

[0038] The steel perforated pipe has multiple functions: as an internal skeleton, it provides radial constraint on the rock mass above the tunnel, improving the integrity and compressive strength of the rock mass in this area and preventing splitting, collapse, or roof fall damage of the rock mass above the tunnel under grouting pressure; as an internal grouting channel, it allows grout to overflow evenly along the entire length of the perforated pipe, avoiding concentrated loss of grout near the borehole opening and improving grouting uniformity; at the same time, it can prevent borehole collapse from causing blockage of the grouting channel and ensure unobstructed grouting channels.

[0039] (iv) Sequential and graded grouting The grouting material used is cement grout.

[0040] Grouting operations are carried out in sequence: First-order hole grouting: Select grouting holes as first-order holes according to the first spacing (such as holes arranged every 8m), and perform grouting first to establish a preliminary water-stopping skeleton.

[0041] Second-order hole grouting: Densify the hole spacing between first-order holes and perform second-order hole grouting to fill the water-stopping blind areas between the initial water-stopping skeleton.

[0042] Sequence III grouting: Further densify the spacing to the final grouting depth, then perform sequence III grouting to form a continuous and dense seepage barrier.

[0043] The grouting pressure is controlled at 0.5–1 MPa. This pressure range is sufficient to force the grout into the rock fissures and displace the fissure water, while being lower than the destructive strength of the rock mass above the tunnel after the perforated pipe reinforcement, thus ensuring construction safety.

[0044] Throughout the grouting process, designated personnel were assigned to observe grout seepage on the tunnel walls inside tunnel 1. When grout seepage was detected at any point within the tunnel, the grouting pressure was immediately reduced and the grout mix ratio adjusted (e.g., by adding a quick-setting agent). After the grout had initially set, the pressure was gradually increased for re-grouting. Through sequential densification and dynamic pressure control, the grouting effect was transformed from "uncontrollable" to "precisely controllable," ensuring that the grout effectively filled the surrounding rock fissures, forming a continuous, dense, and long-lasting water-stopping curtain. This overcame the shortcomings of traditional bare rock grouting, such as limited pressure, severe grout loss, discontinuous water-stopping curtains, and insufficient durability. Curing was carried out after all grouting was completed.

[0045] (v) Construction of slightly inclined drainage holes After the grouting is completed and reaches the designed strength (the cement grout usually needs 7-14 days of curing), construct the drainage hole 3 approximately 1-2 meters above the grouting hole 2. Drainage hole 3 is drilled using a slightly upward (5°-10°) trajectory to ensure the hole opening elevation is lower than the hole bottom elevation, so that the water flow inside the hole has a gravitational component flowing towards the hole opening. A drainage pipe is then inserted into drainage hole 3.

[0046] Drainage hole 3 is used to systematically guide and discharge the remaining groundwater and upstream water after the seepage barrier above the tunnel roof to the outside of the hillside, reducing the water pressure at the tunnel roof. The drainage hole cleverly utilizes the basic principle of water flowing downhill—because the water level inside the tunnel is lower than the upper seepage layer, groundwater naturally seeps into the tunnel; and the drainage hole is located below the seepage layer. After the water-stop curtain is completed and the seepage path is blocked, the drainage hole becomes the smallest energy outlet for groundwater. Groundwater flows smoothly from the higher ground to the outside of the slope through the drainage hole, thus eliminating the driving force for water to seep into the tunnel.

[0047] (vi) Filling the hole with an anti-freezing covering In the area around the drainage hole 3, crushed stones 5 and fine-grained soil 4 are filled to form an anti-freezing cover 7. Specifically, crushed stones 5, preferably with a particle size of 5–20 cm, are first spread in the hole area; then, fine-grained soil 4, preferably coarse sand, is covered on top of the crushed stones 5 to form the anti-freezing cover 7. The thickness of the anti-freezing cover 7 is preferably 2 m, but can be adjusted within the range of 1.5–2.5 m depending on the local frost depth. The anti-freezing cover 7 covers all drainage hole openings and extends outwards.

[0048] The anti-freeze cover 7 utilizes the large porosity of crushed stones to provide water permeability channels and energy dissipation space, and utilizes the thermal insulation properties of fine-grained soil to slow down the temperature change inside the drainage body. This ensures that the drainage body itself has sufficient water permeability, while preventing it from rapidly dropping to the freezing point under extreme low temperature conditions, thus preventing the water at the drainage hole outlet and inside the hole from freezing in winter and avoiding the failure of the drainage hole due to ice blockage.

[0049] (vii) Effect verification After the remediation project was completed, winter monitoring showed a significant reduction in seepage water 6 inside Traffic Tunnel 1, with no water accumulation or ice formation on the road surface inside the tunnel, resulting in a significant improvement in traffic conditions. During the remediation construction period, the traffic tunnel remained open to traffic.

[0050] The aforementioned stages are not isolated construction processes, but rather a synergistic and progressively reinforcing integrated "blocking-draining-prevention" treatment system: the water-stop curtain cuts off the concentrated replenishment path of seepage water into the tunnel at the source, achieving permanent water stoppage; the drainage holes actively depressurize and discharge residual groundwater above the water-stop curtain, further reducing water pressure, improving the reliability of water stoppage, and preventing the curtain from failing under long-term water pressure; the anti-freeze covering ensures the drainage holes remain unobstructed in winter, enabling the entire treatment system to operate effectively in extremely cold environments. This invention, through the system combination of "external interception + upper drainage + anti-freeze" and the key technological innovation of "perforated pipe reinforcement + high-pressure sequential grouting," completely solves the long-standing problem of "blocking leading to re-seepage and drainage leading to freezing" in traditional treatment schemes.

[0051] In this embodiment, the method abandons the traditional passive leak sealing method inside the tunnel and directly constructs an anti-seepage curtain on the outer slope of the mountain at the source of seepage replenishment, completely cutting off the seepage channel. This solves the core defects of existing technologies, such as repeated leakage and only treating the symptoms without addressing the root cause, resulting in permanent treatment effect and significantly improved stability.

[0052] The insertion of steel perforated pipes changes the grouting process from "diffusion" to "conduit" type. The grout enters the predetermined area in an orderly and controllable manner through the grout outlet holes on the steel perforated pipe wall. Combined with layered and sequential grouting (Sequences I, II, and III) and pressure control, the grouting effect changes from "uncontrollable" to "precisely controllable".

[0053] All construction procedures are concentrated on the outer slope of the tunnel, without the need to enter the interior of the traffic tunnel 1, without the need for shutdown, road closure, or traffic interruption, without occupying the traffic cross-section of the traffic tunnel 1, and without the need for expansion and reconstruction. It perfectly matches the management needs of the traffic tunnel in the high-altitude cold region that has been built and opened to traffic during the operation period, with no traffic loss and no construction safety risks.

[0054] The newly added micro-tilted drainage hole 3 and thick anti-freeze cover 7 structure, the anti-freeze cover 7 composed of crushed stone 5 and fine soil 4 cover, is both the heat insulation layer of the drainage structure and the water infiltration channel. It solves the problem of freezing and blockage in winter by utilizing the physical properties of natural materials. It does not rely on external energy, does not require continuous maintenance, has high long-term stability, and achieves stable seepage prevention and drainage throughout the year.

[0055] Compared with the solution of waterproofing after expanding the cross section, the slope drilling and grouting construction site is open, the working conditions are good, and the safety management is easy to achieve; there is no need to interrupt traffic, and the traffic maintenance cost is zero; the materials used in the project (steel pipe, cement grout, crushed stone 5 and fine soil 4) are all conventional building materials, which are easy to obtain and the cost is controllable.

[0056] Simple grouting can only temporarily seal seepage points and cannot eliminate the seepage force of groundwater. With continuous accumulation of water pressure, new seepage channels will inevitably be found. This patent adds a high-level drainage hole 3 to the existing grouting, actively guiding groundwater out of the non-freezing area and eliminating the conditions for seepage into the traffic tunnel 1 from the source, thus achieving permanent grouting. It overcomes the limitations of single grouting sealing technology by using the synergistic effect of grouting to stop water flow and drainage to prevent continuous groundwater pressure from acting on the seepage barrier, preventing damage from water pressure and freeze-thaw cycles, and significantly improving the durability of the treatment structure.

[0057] Example 2: The difference between this example and Example 1 is that the grouting hole 2 terminates at 2.5m above the top of the tunnel; the hole spacing is dynamically adjusted according to geological conditions and grouting effect; the inclination angle of the drainage hole 3 is 5°; and the broken stone layer and fine soil layer in the anti-freeze cover 7 are filled in layers.

[0058] This embodiment is applicable to seepage control in mountain-side transportation tunnels where the surrounding rock at the tunnel top is relatively broken and the fissures are unevenly developed.

[0059] Example 3: The difference between this example and Example 1 is that the grouting hole 2 terminates at 3.5m above the top of the tunnel; the steel perforated pipe adopts a longitudinal groove structure instead of the grouting hole; the inclination angle of the drainage hole 3 is 10°; and the crushed stone 5 and fine soil 4 in the antifreeze cover 7 are mixed and filled.

[0060] This embodiment is applicable to seepage control in mountain-side transportation tunnels with thick overburden and high groundwater pressure.

[0061] Example 4: The difference between this example and Example 1 is that the grouting material used is a cement-water glass dual-liquid grout, which shortens the initial setting time of the grout and is suitable for situations with well-developed fissures and high groundwater flow velocity. During the grouting process, the water glass dosage is dynamically adjusted according to the grout seepage situation in the tunnel to control the initial setting time of the grout within an appropriate range.

[0062] This embodiment is applicable to the treatment of seepage in mountain-side traffic tunnels with large seepage volume and fast fissure water flow velocity.

[0063] Example 5: This example provides a method for dynamically adjusting the spacing of grouting holes. In step one, the initial spacing of grouting holes 2 is 3m. After the grouting of the first-order holes in step three is completed, the grouting volume of each grouting hole is recorded. The uniformity of the development of fractures in the surrounding rock is judged based on the grouting volume of each first-order hole. If the grouting volume of adjacent first-order holes differs greatly, it indicates that the fracture development in this area is uneven and the grouting volume requirement varies greatly. In this area, the hole spacing needs to be increased and the spacing reduced. If the grouting volume of adjacent first-order holes is small and the difference is not significant, it indicates that the surrounding rock in this area is intact and the fractures are not developed. The hole spacing can be appropriately widened. By dynamically adjusting the spacing based on the difference in grouting volume, the final water-stopping curtain achieves optimal matching between hole spacing and grouting volume while ensuring continuity. This avoids material waste due to excessive grouting or the formation of water-stopping blind zones due to excessive hole spacing. It has good adaptability to rock masses with uneven fracture development.

[0064] In summary, the technical principle of this invention can be summarized as a three-stage synergistic mechanism: first, forming a water-stop curtain above the tunnel roof; second, actively draining water from a high position to relieve pressure; and finally, providing antifreeze protection for the drainage outlet. 1. The principle of sealing – establishing a water-stop curtain. A horizontal grouting hole 2 is drilled near the outer slope of tunnel 1 to a point approximately 3m above the tunnel ceiling. A steel perforated pipe is then inserted into grouting hole 2, followed by layered and sequential grouting. The grouting pressure is controlled between 0.5 and 1 MPa. The grout diffuses and solidifies along the fissures in the surrounding rock, forming a continuous and dense horizontal water-stop curtain above the tunnel ceiling. The steel perforated pipe is permanently left in place, simultaneously providing physical reinforcement to the surrounding rock above the tunnel, thus integrating reinforcement and water-stopping into one process.

[0065] 2. Drainage Principle – High-Level Directional Pressure Relief. Drainage holes 3, slightly inclined upwards (5°–10°), are drilled approximately 1–2 meters above the cutoff wall (i.e., the seepage recharge zone) to actively guide groundwater to the outside of the hillside for discharge. Drainage holes 3 cleverly utilize the basic principle of water flowing downhill – because the water level inside the tunnel 1 is lower than the upper seepage layer, groundwater naturally seeps into the tunnel 1; and since the orifice of drainage hole 3 is positioned below the seepage layer, after the cutoff wall is completed and the seepage path is blocked, drainage hole 3 becomes the smallest energy outlet for groundwater. Water flows smoothly from a higher position through drainage hole 3 to the outside of the slope, thus eliminating the driving force for water to seep into the tunnel 1.

[0066] 3. Principle of protection – Anti-freezing protection of drainage outlets. A 2m thick layer of crushed stones 5 and fine-grained soil 4 (i.e., anti-freezing cover 7) is placed over the drainage hole 3. This cover utilizes the large pore structure of the crushed stones 5 and the heat-insulating properties of the fine-grained soil 4 to slow down temperature changes inside the anti-freezing cover 7, preventing it from rapidly dropping to freezing point under extreme low temperatures. Simultaneously, it ensures sufficient permeability of the anti-freezing cover 7, allowing seepage water 6 to drain smoothly without forming ice blockages at the hole opening.

[0067] 4. Synergistic Effect of the Three Stages. The three stages mentioned above are not isolated construction processes, but rather work together and enhance each other step by step: the water-stop curtain cuts off the concentrated replenishment path of seepage water 6 into the traffic tunnel 1 at the source; the drainage hole 3 actively relieves pressure and discharges the residual groundwater above the water-stop curtain, further reducing water pressure and improving the reliability of water-stopping; the anti-freeze cover 7 ensures the continuous unobstructed flow of the drainage hole 3 in winter, enabling the entire treatment system to operate effectively even in extremely cold environments.

[0068] The beneficial effects of the technical solution of this invention are reflected in three aspects: technical effects, economic effects, and social effects. (1) Technical effects Completely eliminates seepage and freezing: By using a continuous grouting curtain 3m above the tunnel ceiling, the main channel for groundwater to seep into the tunnel is cut off, reducing the amount of seepage from the source and fundamentally alleviating or eliminating the freezing phenomenon in winter.

[0069] Ensuring structural safety: The perforated pipe reinforcement keeps the rock mass at the top of the tunnel stable during high-pressure grouting, avoiding the risk of tunnel roof collapse that may be caused by traditional high-pressure grouting; at the same time, the grouting stone and the perforated pipe together improve the integrity and long-term stability of the rock mass at the top of the tunnel.

[0070] The system is durable and reliable: the water-stop curtain is located inside the rock mass, avoiding the direct impact of drastic temperature and humidity changes and vehicle vibrations inside the tunnel; anti-freezing measures at the drainage outlets ensure the continuous operation of the drainage system during winter. The durability of the entire treatment system is significantly better than that of surface sealing measures inside the tunnel.

[0071] Adaptable to complex geology: Sequential grouting allows for dynamic adjustment of hole spacing and grouting parameters according to geological conditions, and has good adaptability to rock masses with uneven fracture development.

[0072] (2) Economic effects Saving on project investment: Compared with the "enlarged cross section + full cross section lining" scheme, this scheme does not require excavation inside the tunnel and concrete lining, and only targets the parts where water seeps out, which greatly reduces the amount of work and can usually reduce the cost by more than 90%.

[0073] Reduced traffic losses: Construction does not require traffic interruption, avoiding losses and social costs caused by road closures.

[0074] Reduced maintenance costs: After a one-time system treatment, the recurrence rate of seepage is extremely low, avoiding the repeated investment of existing technologies in the process of "treatment-recurrence-retreatment".

[0075] (3) Social effects Ensuring traffic safety: Eliminating the risk of ice formation inside the cave, significantly reducing the risk of traffic accidents in winter, and protecting the lives and property of people.

[0076] Protecting the ecological environment: The slope construction causes minimal disturbance to the mountain, and the drainage holes systematically drain groundwater, preventing the disorderly flow of seepage water inside the tunnel from polluting the environment outside the tunnel.

[0077] Extending the service life of traffic tunnels: This provides a feasible solution for extending the service life of early unlined traffic tunnels, avoiding the need for tunnel abandonment and reconstruction due to water seepage problems.

[0078] The embodiments of the present invention also provide the following alternatives: While meeting the core invention objectives of ensuring uninterrupted operation of mountain tunnels in high-altitude and cold regions, eliminating water seepage, preventing freezing and blockage, and not occupying cross-sections, there are some equivalent alternative solutions, but all of them have certain shortcomings and cannot completely surpass the technical solution of this patent.

[0079] Alternative Option 1: Slope Inclined Hole Grouting + Heated Drainage Ditch Inside the Tunnel. This option involves drilling inclined holes (not horizontal, with a large inclination angle) into the slope for water sealing, while simultaneously installing an electrically heated drainage ditch inside the tunnel to prevent icing. While inclined hole grouting allows for slope construction, the angle between the inclined hole trajectory and the direction of the cracks in the tunnel roof is uncertain, making it difficult to guarantee grout uniformity. The electric heating inside the tunnel requires a large amount of electricity over a long period, resulting in extremely high operating costs, and the heating equipment fails immediately upon malfunction. This option is feasible in terms of "not encroaching on the cross-section," but is significantly inferior to this option in terms of "long-term economic efficiency."

[0080] Alternative Option 2: Minimally Invasive Grouting Inside the Tunnel + Laying De-icing Cables on the Road Surface. This option involves injecting rapid-setting chemical grout through small holes drilled in the tunnel walls, while simultaneously laying de-icing cables under the road surface. Minimally invasive grouting still falls under the category of bare rock grouting inside the tunnel, resulting in poor water-stopping effects and a high recurrence rate. The de-icing cables only address road surface icing, failing to solve the problem of ice cones encroaching on the tunnel walls, and also consume enormous amounts of energy. This option fails to achieve the goal of "completely eliminating seepage."

[0081] Alternative Option 3: Implement drainage holes without grouting to stop the water flow. This option involves drilling horizontal drainage holes on the slope to directly drain groundwater from the tunnel roof without grouting. While this can draw groundwater out and reduce seepage within the tunnel, the drainage holes must bear all incoming water for an extended period. The holes are prone to expansion due to erosion from the flow velocity, resulting in poor long-term stability. Furthermore, the drainage holes themselves are at risk of freezing in winter (although they can be covered for frost protection, the cover layer may become saturated and freeze when the inflow is high). This option is essentially "drainage without interception," failing to achieve the goal of "systematic management," and its long-term effectiveness is unreliable.

[0082] Alternative Solution 4: Geotechnical Insulation Layer Replaces Soil-Rock Freeze-Proof Drainage Body. This solution uses composite geotechnical insulation material to cover the openings, replacing the crushed stone and fine-grained soil freeze-proof covering. However, in high-altitude, cold, and windy environments with freeze-thaw cycles, geotechnical materials are prone to aging, damage, and failure, exhibiting poor durability and lacking permeable drainage function, easily leading to water accumulation. Therefore, its long-term performance is far inferior to the crushed stone-fine-grained soil composite structure of this patent.

[0083] The aforementioned alternatives either have significant defects in technical effectiveness or are clearly inferior to this solution in terms of economy and durability. This patented solution, through the system combination of "external interception + top drainage + antifreeze" and the key technological innovation of "perforated pipe reinforcement + high-pressure sequential grouting," has the best comprehensive technical and economic performance in achieving the purpose of the invention and is currently the preferred solution for solving this type of engineering problem.

[0084] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for treating seepage water during the operation of a mountain-side transportation tunnel in a high-altitude, cold region, characterized in that, Includes the following steps: Step 1: Drill into the rock mass above the tunnel from the outer slope of the mountain access tunnel to form a grouting hole that runs from the slope surface to the rock mass above the tunnel top; Step 2: Insert a steel perforated pipe into the grouting hole. The pipe wall of the steel perforated pipe has grout outlet holes. The perforated pipe section corresponds to the surrounding rock within a set range above the tunnel top. Step 3: Grout is injected into the fissures of the surrounding rock through the steel pipe. After the grouting is completed, an anti-seepage curtain is formed in the rock mass above the tunnel. Step 4: Construct drainage holes above the grouting holes. The drainage holes are drilled from the slope surface into the rock mass above the tunnel roof. The termination position of the drainage holes is located above the seepage prevention curtain, and the drainage holes are horizontal holes with a slight upward inclination. Step 5: Fill the drainage hole opening and surrounding area with crushed stones and fine soil to form a frost-proof covering for the opening.

2. The method for treating seepage water during the operation of mountain tunnels in high-altitude and cold regions according to claim 1, characterized in that, In step one: the termination position of the grouting hole is 2.5 to 3.5m above the top of the tunnel; The spacing between the grouting holes is 1.5 to 2.5 m, and they are arranged linearly along the tunnel axis. The inclination angle of the grouting hole is 0° to 5°.

3. The method for treating seepage water during operation of mountain tunnels in high-altitude and cold regions according to claim 1, characterized in that, In step two: the perforated section of the steel perforated pipe corresponds to the rock mass within a thickness range of 2.5 to 3.5 meters above the tunnel ceiling; The steel pipe has grouting holes or longitudinal grooves arranged in a quincunx pattern on its wall.

4. The method for treating seepage water during operation of mountain tunnels in high-altitude and cold regions according to claim 1, characterized in that, In step three: the grouting is carried out according to the principle of sequence, and is carried out in sequence I holes, II holes, and III holes in order of increasing density; The grouting pressure is controlled at 0.5–1 MPa.

5. The method for treating seepage water during the operation of mountain tunnels in high-altitude and cold regions according to claim 4, characterized in that, The first sequence holes are grouting holes arranged at the first interval to establish a preliminary water-stopping skeleton; The second-order holes are grouting holes arranged densely between the first-order holes to fill the water-stopping blind areas between the initial water-stopping skeleton; The third sequence holes are further densified grouting holes, forming a continuous and dense seepage-proof curtain.

6. The method for treating seepage water during operation of mountain tunnels in high-altitude and cold regions according to claim 1, characterized in that, In step four: the drainage hole is located 1-2m above the grouting hole; The inclination angle of the drainage hole is 5° to 10°.

7. The method for treating seepage water during operation of mountain tunnels in high-altitude and cold regions according to claim 1, characterized in that, In step five: the particle size of the crushed stone is 5-20 cm; The fine-grained soil is sandy soil; The thickness of the antifreeze cover is 1.5 to 2.5 m.

8. The method for treating seepage water during operation of mountain tunnels in high-altitude and cold regions according to claim 1, characterized in that, In step three: During the grouting process, monitor the grout seepage inside the tunnel. When grout seeps out inside the tunnel, reduce the grouting pressure or adjust the grout mix ratio. After the grout has initially set, increase the pressure and re-grout.

9. The method for treating seepage water during operation of mountain tunnels in high-altitude and cold regions according to claim 1, characterized in that, In step four: a drainage pipe is inserted into the drainage hole.

10. The method for treating seepage water during the operation of mountain tunnels in high-altitude and cold regions according to claim 3, characterized in that, In step one: the spacing between grouting holes is adjusted according to the difference in grouting volume of each grouting hole. When the difference in grouting volume between adjacent grouting holes exceeds the set threshold, the hole spacing is increased. When the difference in grouting volume between adjacent grouting holes is less than the set threshold, the hole spacing is increased.

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