Construction method and construction system for blocking flowing water channel in grading mode

Abstract

The invention relates to the technical field of tunnel underground water treatment, in particular to a construction method and a construction system for blocking a flowing water channel in a grading mode. According to the method, a steel pipe grating framework is placed in a flowing water channel in the direction perpendicular to water flow, and a first-stage water stop body is formed; a plurality of water-permeable and slurry-impermeable film bags are arranged on the upstream side of the steel pipe grating framework, cement slurry is injected into each film bag, and after the film bags and the cement slurry are solidified, a second-stage water stop body is formed; and ordinary cement grouting is conducted on the remaining gaps among the multiple film bags, and a third-level reinforcing layer is formed. According to the method, a three-order cooperative structure of a steel pipe grating framework, a film bag water stop body and a conventional grouting layer is sequentially established, a three-dimensional protection system is formed, high-pressure large-flow gushing water is effectively blocked, the water blocking rate is larger than 95%, the water leakage risk in the tunnel operation period is remarkably reduced, the engineering durability is improved, long-term stable operation of traffic infrastructures is guaranteed, and the service life of the tunnel is prolonged. The method has the advantages of high efficiency, low operation and maintenance cost, high construction safety, environmental protection and the like.

Description

Technical Field

[0001] This invention relates to the field of tunnel groundwater treatment technology, and more specifically, to a construction method and system for graded sealing of flowing water channels. Background Technology

[0002] When tunnels traverse areas with highly developed karst topography, they often encounter flowing water channels connected to surface underground rivers, large karst cavities, or high-pressure fissure conduits. These channels typically exhibit the following hydrogeological characteristics: high flow velocity, generally exceeding 1.5 m / s in measured values, and even reaching 4-5 m / s or higher under extreme conditions; high water pressure, with static pressure generally above 0.8 MPa, and exceeding 2 MPa in deeply buried tunnels; and concentrated flow, with instantaneous water inrushes often exceeding 500 m³ / h. 3 / h, in the form of a catastrophic surge; the channel morphology is complex, with drastic changes in the diameter of the cavities or the opening of the fissures, and local "throat" or "inverted siphon" structures.

[0003] The above conditions cause conventional materials such as traditional cement grouting to be diluted by high-speed water flow during the injection process, making it difficult for them to deposit and solidify at the predetermined location, resulting in the technical bottleneck of "not being able to be injected, not being able to be retained, and not being able to be sealed tightly".

[0004] Specifically, the one-time sealing method using quick-setting paste is ineffective in sealing high-flow-rate, water-rich sections, and the high dosage of quick-setting agent increases material costs by 60%-80%. Drilling for pressure relief and backfilling with concrete requires large-scale construction, and the concrete is prone to segregation in flowing water, resulting in "sandwich" or "hollow shell" phenomena, leading to a leakage rate of over 40% in the later stages.

[0005] Currently, the average water-blocking rate of water-rich sections that have been sealed using conventional methods is only about 30%, making it difficult to achieve safe, efficient, and economical management of high-pressure water inrush in karst tunnels. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a construction method and construction system for graded sealing of flowing water channels.

[0007] The technical solution of the present invention to solve the above-mentioned technical problems is as follows: This invention provides a construction method for staged sealing of flowing water channels, comprising the following steps: S1. A steel pipe grid frame is placed in the water channel in a direction perpendicular to the water flow to form a primary water stop. S2. Multiple water-permeable but grout-impermeable membrane bags are installed on the water-facing side of the steel pipe grid frame, and cement grout is injected into each membrane bag. After the membrane bag and cement grout have solidified, a secondary waterstop is formed. S3. Ordinary cement grouting is performed on the remaining gaps between the multiple membrane bags to form a three-level reinforcement layer.

[0008] Based on the above technical solution, the present invention can be further improved as follows.

[0009] Furthermore, the steel pipe grid frame is composed of multiple steel pipes with a diameter of 70-80 mm and a wall thickness of 6-10 mm, arranged in a matrix with a center distance of 150-250 mm, to reduce the water flow velocity by 25-40%.

[0010] Furthermore, the density of the membrane bag fabric is 250-350 g / m³. 2 The equivalent aperture O90 is 0.06-0.08 mm, and the tensile strength is greater than or equal to 45 kN / m.

[0011] Furthermore, the membrane bag fabric is double-layered, with the outer layer being polypropylene woven fabric and the inner layer being polyester nonwoven fabric.

[0012] Furthermore, the cement paste is a cement paste, the components of which include P.O42.5 cement, ultrafine mineral powder, silica fume, polycarboxylate superplasticizer and water.

[0013] Furthermore, the cement slurry is a modified paste, the components of which include P.O42.5 cement, ultrafine mineral powder, silica fume, polycarboxylate superplasticizer, water, and also aluminum sulfate-based quick-setting agent and cellulose ether anti-dispersant.

[0014] Furthermore, in step S2, the modified paste is injected in a bottom-up, skip-hole sequence. During the injection process, the unfolding rate of the membrane bag is monitored in real time to ensure that the unfolding rate of the membrane bag is greater than or equal to 95% under the condition that the high flow rate during injection is less than or equal to 5 m / s.

[0015] Furthermore, the injection of the modified paste includes the following steps: S2-1, Grouting during the filling period: Grouting is carried out at a pressure of 0.3~0.5MPa and a flow rate of 40~60L / min until the membrane bag expands to 90% of the design volume; S2-2, Grouting during the compaction stage: Use a grouting pressure of 0.5~0.8MPa and a flow rate of 20~30L / min to inject grout and remove residual air and water; S2-3, Grouting during the stabilization period: Grouting is carried out at a pressure of 1.0 MPa and a flow rate of 5-10 L / min to form a dense stone body.

[0016] Furthermore, before step S1, the flow velocity v of the flowing water in the water channel is detected in real time, and construction is carried out based on the flow velocity v. The determination method is as follows: When the dynamic water flow velocity v is less than 2 m / s, proceed directly to step S2; When the dynamic water flow velocity is greater than or equal to 2 m / s, step S1 is executed first, followed by steps S2 and S3 in sequence.

[0017] The present invention also provides a construction system as described above, comprising: the steel pipe grid skeleton, the membrane bag, the cement slurry, and the ordinary cement; and further comprising a positioning and lowering device, an intelligent grouting pump station, and a monitoring system, wherein the monitoring system is used to collect flow velocity, pressure, and flow rate.

[0018] The beneficial effects of this invention are as follows: (1) The construction method of the graded sealing of the water channel of the present invention establishes a three-stage collaborative structure of steel pipe grid skeleton, membrane bag water stop body and conventional grouting layer in sequence to form a three-dimensional protection system similar to "skeleton + muscle + skin" so as to effectively seal high pressure and large flow of water. (2) The construction method of the graded sealing of the water channel of the present invention uses membrane bags and cement grout to establish a secondary water stop body. Combined with the grouting process, it can effectively reduce grout loss, reduce material waste, and improve construction efficiency and the strength of the stone body. (4) The construction method of graded sealing of the water channel of the present invention has a water blocking rate of more than 95%, which can significantly reduce the risk of water leakage during tunnel operation, improve the durability of the project, and ensure the long-term stable operation of transportation infrastructure. (5) The construction method of the graded blocking of the water channel of the present invention is efficient, low in operation and maintenance cost, and has effectively improved construction safety. It also has the advantages of enhanced engineering reliability and environmental protection. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure of the steel pipe grid skeleton, membrane bag, and conventional quick-setting grout injection position in an embodiment of the present invention; Figure 2 for Figure 1 B-B' cross-section. Detailed Implementation

[0020] The principles and features of the present invention are described below. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0021] The construction method for graded sealing of flowing water channels of the present invention includes the following steps: S1. A steel pipe grid frame is placed in the water channel in a direction perpendicular to the water flow to form a primary water stop. S2. Multiple permeable but impermeable membrane bags are installed on the water-facing side of the steel pipe grid frame, and cement grout is injected into each membrane bag. After the grout in the membrane bag solidifies, a secondary waterstop is formed. S3. Ordinary cement grouting is applied to the remaining voids of the secondary waterstop to form a tertiary reinforcement layer.

[0022] This invention discloses a tiered method for sealing karst channels. A steel pipe grid framework, the injection of cement grout into membrane bags to form a membrane bag grouting body, and conventional quick-setting grout injection create a three-dimensional composite structure resembling a "skeleton + muscle + skin." This method breaks through the traditional single grouting mode, achieving a three-dimensional sealing system. The steel grid achieves primary interception (flow velocity reduction of 25%-40%), the membrane bag grouting completes secondary sealing (interception rate > 75%), and finally, ordinary cement grout (or quick-setting grout) provides tertiary reinforcement, effectively sealing high-pressure, high-flow-rate water. Multiple membrane bags can create a stagnant or low-flow-rate water environment. In dynamic or high-velocity water environments, the grout is easily washed away. After creating a stagnant environment, supplementary conventional grouting effectively seals the karst channels.

[0023] The construction method of this invention effectively controls the risk of sudden water inrush through a "step-by-step deceleration and three-dimensional interception" mechanism, reducing the occurrence of geological disasters such as surrounding rock instability and collapse, and ensuring the safety of construction personnel. It successfully overcomes the industry problem of the difficulty in shaping the grout body in a high-velocity (4.5m / s) dynamic water environment, filling the technical gap in tunnel water plugging under complex hydrogeological conditions.

[0024] The construction method of this invention is applicable to water-rich sections, and is particularly suitable for tunnels that meet the following conditions: Hydrogeology: Karst conduit flow with confined head >100m and flow velocity 1.0-5m / s.

[0025] Special operating conditions: Disastrous water inrush with a flow rate > 500 m³ / h.

[0026] Cavity dimensions: channel diameter ≥ 0.50m, or fissure width ≥ 0.5m.

[0027] Rock mass conditions: The surrounding rock is of grade IV or above, with no large fault fracture zones.

[0028] In the construction method of the present invention, the steel pipe grid frame is composed of multiple steel pipes with a diameter of 70-80 mm and a wall thickness of 6-10 mm, arranged at a center distance of 150-250 mm, which can reduce the water flow velocity by 25-40%.

[0029] Preferably, the steel pipes are arranged in a quincunx pattern. Through the turbulence effect of the steel grating, turbulence can be further generated, reducing the flow velocity.

[0030] Preferably, the steel pipe ends of the steel pipe grating are provided with trapezoidal threads, and adjacent steel pipes are connected by threads and fastened with a torque of 450±50 N·m to form a three-dimensional skeleton that can withstand ≥1.5 MPa surrounding rock pressure.

[0031] Preferably, the density of the membrane bag fabric is 250-350 g / m². 2The equivalent pore size O90 is 0.06-0.08 mm, and the tensile strength is greater than or equal to 45 kN / m; the material of the geomembrane bag is polyester filament geomembrane bag.

[0032] This invention relates to membrane bag grouting technology, which uses a geomembrane bag made of polymer material to encapsulate the grout, utilizing its water-permeable but grout-impermeable properties to achieve effective sealing in dynamic water environments. Under grouting pressure, the membrane bag allows free water to seep out through the fabric pores, while cement particles are trapped, causing the water-cement ratio of the grout to automatically decrease, forming a high-density stone mass.

[0033] The membrane bag of this invention has a dynamic water separation function. Its equivalent pore size is 0.06-0.08 mm. Under a grouting pressure of 0.5-1.2 MPa, the water in the grout is separated out according to Darcy's law, and the water-cement ratio can be reduced from the initial 0.8 to below 0.5, and the strength of the stone body is increased to 25 MPa (3d). At the same time, the membrane bag also has erosion resistance. The tensile strength of the membrane bag is ≥45 kN / m, which can withstand the erosion of flowing water with a velocity of 5 m / s. The membrane bag also has a good three-dimensional encapsulation effect. After filling, it forms a continuous closed body with a permeability coefficient ≤1×10-7 cm / s.

[0034] Compared to traditional grouting processes where the grout loss rate exceeds 30%, the membrane bag grouting technology of this invention reduces the grout loss rate to less than 5%. The early strength of the grouted stone can be increased by 2-3 times; it is suitable for dynamic water environments with water pressure ≤2MPa and flow velocity ≤5m / s. After membrane bag grouting is completed, a secondary interception is formed, with an interception rate greater than 75%.

[0035] Preferably, the film bag fabric is double-layered, with the outer layer being polypropylene woven fabric and the inner layer being polyester nonwoven fabric.

[0036] Preferably, the cement paste is a neat cement paste, the components of which include P.O42.5 cement, ultrafine mineral powder, silica fume, polycarboxylate superplasticizer and water.

[0037] In the aforementioned cement slurry, P.O42.5 cement, ultrafine mineral powder, and silica fume form a dense packing, reducing porosity; polycarboxylate superplasticizer ensures good fluidity of the slurry even at low water-cement ratios. Aluminum sulfate-based accelerators allow for flexible adjustment of the initial setting time to 5-30 minutes, and cellulose ethers, acting as anti-dispersing agents, significantly reduce slurry loss. Using this cement slurry allows the final aggregate to achieve a 3-day strength of 10-15 MPa and maintain its integrity under continuous water flow.

[0038] Further preferred, the specific proportions of each component are: 100 parts P.O42.5 cement, 20-30 parts ultrafine mineral powder, 10-15 parts silica fume, 0.5-0.8 parts polycarboxylate superplasticizer, and 60-70 parts water.

[0039] Further preferred, the specific surface area of ​​P.O42.5 cement is ≥350 m². 2 / kg, d90≤15μm of ultrafine mineral powder, SiO2≥92% in silica fume; water reduction rate of polycarboxylate superplasticizer ≥25%, water used requires pH 7±1 and chloride ion ≤50 mg / L.

[0040] Preferably, the cement paste is a modified paste, the components of which include P.O42.5 cement, ultrafine mineral powder, silica fume, polycarboxylate superplasticizer, water, and also aluminum sulfate-based quick-setting agent and cellulose ether anti-dispersant.

[0041] For modified cement paste, adding 2%-5% aluminum sulfate-based quick-setting agent to the total mass of cement paste can flexibly adjust the initial setting time to 5-30 min; adding 0.1%-0.3% cellulose ether as an anti-dispersant significantly reduces slurry loss. The final aggregate can achieve a 3-day strength of 10-15 MPa and remain intact in continuous water flow.

[0042] In step S2, the modified paste is injected in a bottom-up, skip-hole sequence. During the injection process, the unfolding rate of the membrane bag is monitored in real time to ensure that the unfolding rate of the membrane bag is greater than or equal to 95% under the condition that the high flow rate during injection is less than or equal to 5 m / s.

[0043] Preferably, the injection of modified paste includes the following steps: S2-1, Grouting during the filling period: Grouting is carried out at a pressure of 0.3~0.5MPa and a flow rate of 40~60L / min until the membrane bag expands to 90% of the design volume; S2-2, Grouting during the compaction stage: Use a grouting pressure of 0.5~0.8MPa and a flow rate of 20~30L / min to inject grout and remove residual air and water; S2-3, Grouting during the stabilization period: Grouting is carried out at a pressure of 1.0 MPa and a flow rate of 5-10 L / min to form a dense stone body.

[0044] Specifically, the mathematical relationship between grouting pressure and hydrodynamic pressure is established as follows: Pnote = Pmoving + 0.2~0.4 MPa.

[0045] The above steps established a dynamic balance control system for water flow and grouting, successfully achieving a membrane bag expansion rate of over 95% in a high-speed water flow environment of 4.5 m / s, thus overcoming the industry problem of difficult shaping of high-flow-rate grout bodies.

[0046] Preferably, before step S1, the flow velocity v of the flowing water in the water channel is detected in real time, and construction is carried out according to the flow velocity v. The determination method is as follows: When the dynamic water flow velocity v is less than 2 m / s, proceed directly to step S2; When the dynamic water flow velocity is greater than or equal to 2 m / s, first execute step S1, then execute steps S2 and S3 in sequence.

[0047] The above-mentioned judgment method realizes the flow velocity classification response technology. When the dynamic water flow velocity v is low, only membrane bag grouting and conventional grouting are used, without the need for steel pipe grid skeleton, which reduces the construction difficulty and cost. When the frozen water flow velocity is high, steel pipe grid skeleton is introduced to implement the graded sealing construction of the present invention, effectively achieving the sealing effect.

[0048] The ordinary cement grouting of the present invention can be performed using any conventionally used cement and through a general grouting method. In one embodiment, a two-liquid grout system can be used, where liquid A is a pure cement grout (d50=8μm) and liquid B is an additive (tackifier, foaming agent), and the gelation time can be controlled within the range of 30s to 10min.

[0049] The present invention also provides a construction system for the construction method, comprising: a steel pipe grid frame, a membrane bag, cement grout, and ordinary cement; it also includes a positioning and lowering device, an intelligent grouting pump station, and a monitoring system, wherein the monitoring system is used to collect flow velocity, pressure, and flow rate; the construction system can realize the three-dimensional sealing system of the present invention and effectively seal high-pressure, high-flow water inrush.

[0050] The present invention will be specifically described below through examples: Example This embodiment describes a tunnel project constructed in a water-rich section, specifically the Dejiang Tunnel on the Dewu Expressway, where the maximum dynamic water flow velocity is 4.5 m / s. The overall construction process includes: ground-penetrating radar detection, 3D modeling of the karst cavity, construction plan design, borehole positioning, steel grating installation, membrane bag grouting, conventional grouting, effect testing, and lining construction.

[0051] like Figure 1 and Figure 2 As shown, the specific construction process of this embodiment is as follows: S1. A steel pipe grid frame is placed in the water channel in a direction perpendicular to the water flow to form a primary water stop.

[0052] A Φ76 steel pipe array, spaced 200 mm apart in a staggered pattern, creates a non-uniform flow field. Calculations based on the Navier-Stokes equations show that when water flows through the grid, boundary layer separation occurs, resulting in the Karman vortex street effect. This reduces the Reynolds number from 10⁵ to the order of 10⁴, and the velocity distribution transitions from laminar to turbulent. The measured kinetic energy loss coefficient reaches 0.82. Simultaneously, the steel pipe matrix generates flow resistance. According to Darcy's formula, each meter of grid generates a hydrodynamic pressure gradient of 9.8 kN / m², effectively reducing the flow velocity by 42%-65%.

[0053] In this embodiment, the specific steps for installing the steel grating are as follows: (1) Drilling Positioning Control: Before construction, an independent coordinate system is established, and a total station with an angle measurement accuracy of 0.5″ is used for layout. After the layout is completed, the hole position is marked on the rock surface with cross lines, and reflective tape is added to ensure that the visibility distance at night is greater than 20m. Then, based on the water flow velocity v and the water head H, the angle between the borehole axis and the water flow direction is calculated according to θ=arctan(v / 2gH) to determine the three-dimensional trajectory.

[0054] (2) Complex formation treatment: If the drill bit gets stuck during drilling, immediately inject an unsticking agent consisting of 5% emulsified oil and 2% surfactant, and use an impactor with a frequency of 15 Hz and an amplitude of 3 mm to vibrate and unstick the drill bit; if water gushing in, first install a water stopper with a pressure resistance of 5.0 MPa at the borehole opening, and then use air lift pressure of 0.7–1.0 MPa for reverse circulation to remove slag, so as to ensure safe drilling.

[0055] (3) Hole quality inspection: After the hole is formed, the hole diameter is continuously measured with a mechanical well caliper at a sampling interval of 0.2 m, and the hole diameter curve is plotted. The allowable deviation of the hole diameter is +20 mm / 0 mm. If the requirement is not met, the hole is repaired again.

[0056] (4) Pre-installation treatment of steel pipes: After the steel pipes arrive at the site, Tr76×6 trapezoidal threads are machined at the ends, with an effective thread length of not less than 80 mm; at the same time, a 30° V-shaped bevel is machined with a blunt edge of 1.5 mm to prepare for subsequent connection.

[0057] (5) Threaded connection construction: Before connection, blow with compressed air and wipe the threads with acetone, then apply thread sealant with molybdenum disulfide content ≥60%; after manually screwing in 35 turns, switch to hydraulic wrench, initial tightening torque 150 N·m to eliminate gap, final tightening torque 450±50 N·m, and check the wrench reading to ensure joint sealing and load-bearing performance.

[0058] (6) Anchoring at the borehole: After the steel pipe is connected, inject early-strength cement mortar with a strength of ≥15 MPa for 3 hours into the borehole; control the grouting pressure at 0.3–0.5 MPa and stabilize the pressure for no less than 10 minutes to solidify the steel pipe with the surrounding rock.

[0059] (7) Construction of grid matrix: Three-dimensional control points are set up at 5 m intervals, with a forced centering accuracy of ±0.2 mm. The total station is set up freely, with no less than 3 backsight points and 2 rounds of measurement to form a measurement control network. Then, the node coordinates are collected, and the least squares method is used for adjustment, with a residual limit of ±2 mm. The deviation vectors in the X, Y, and Z directions are displayed in real time. The position of each steel pipe is adjusted to finally form a grid matrix that meets the design accuracy.

[0060] S2. Several permeable but impermeable membrane bags are installed near the downstream position of the steel pipe grid frame, and cement grout is injected into each membrane bag. After the grout in the membrane bag has solidified, a secondary waterstop is formed.

[0061] The membrane bag grouting system in this embodiment consists of high-performance membrane bags, specialized grouting materials, and a complete set of equipment. Through a three-step closed-loop process of "precise positioning—controllable grouting—stage molding," it achieves the goal of low-loss, high-strength, and rapid-hardening sealing in a high-pressure dynamic water environment. The specific process is as follows: This embodiment uses a double-layer film bag, with the outer layer made of 200 g / m³ film. 2 The polypropylene woven fabric has a warp tensile strength of not less than 35 kN / m, which is sufficient to withstand the instantaneous impact of a flow velocity of 5 m / s; the inner layer is 100 g / m². 2 Made of polyester nonwoven fabric with an equivalent pore size (O90) of 0.06 mm, it allows water permeability and grout retention under grouting pressures of 0.5–1.2 MPa, completing the "dynamic water separation" process. The bag body is constructed using high-frequency hot-melt welding, with a weld peel strength ≥8 kN / m, ensuring an overall seal. A 50 mm wide reinforcing strip is added every 300 mm circumferentially to prevent bulging and deformation, and to facilitate folding and transportation. Standard sizes include 1.0 m × 1.5 m, 1.0 m × 2.0 m, and 2.0 m × 3.0 m, and custom-shaped bags can also be made to fit the contours of the grout cavity to meet different space requirements.

[0062] According to Stokes' law, the water migration rate in the grout is v = ΔP·d² / (32μL), where d = 0.05mm (cement particle size) and μ = 1.002×10⁻³Pa·s (water viscosity at 20℃). The calculated water separation rate can reach 15%-20%, which reduces the initial water-cement ratio of 0.8 to 0.5, the porosity of cement stone from 35% to 18%, and the 3-day compressive strength increases by 2.3 times.

[0063] The cement paste used in this embodiment is a modified paste, with the following specific components and proportions: 100 parts of P.O42.5 cement, 25 parts of ultrafine mineral powder, and 15 parts of silica fume. Based on the total mass of cement paste as 100%, 2% aluminum sulfate-based quick-setting agent and 0.2% cellulose ether are added.

[0064] This step specifically utilizes a dual-liquid grouting pump for grouting, with a rated pressure of 8 MPa and a flow rate of 0-100 L / min, infinitely adjustable. It can be used as a single pump or in parallel with two pumps, achieving a three-stage pressure-flow curve of "filling-compacting-pressure stabilization." The intelligent control system collects three parameters—pressure, flow rate, and grout specific gravity—in real time with an accuracy of ±0.5%. If the deviation exceeds the set threshold, an alarm is immediately triggered and automatic adjustments are made to ensure the grouting process is within the "set window." An auxiliary membrane bag positioner utilizes ultrasonic ranging with an accuracy of ±10 mm, allowing real-time display of the gap between the membrane bag and the borehole wall during the lowering stage, preventing skewing or entanglement.

[0065] The specific construction process in this embodiment follows the flow of "quincunx-shaped hole layout—Z-shaped folding—gradual grouting". On-site layout is first done using a total station, with a hole network of 1.0 m × 1.0 m, a horizontal position deviation ≤ 30 mm, and an elevation deviation ≤ 20 mm. Before leaving the factory, the membrane bags are folded in a "Z" shape and secured with straps to reduce volume and prevent kinking during lowering. A Φ42 mm galvanized steel pipe is used as a guide, and the traction rope also serves as the grouting pipe, completing bag delivery and positioning in one step. The grouting pipeline uses a Φ76 mm high-pressure hose as the main channel, branching in a tree-like pattern to a Φ25 mm sleeve valve pipe, with a grout stop valve at the end. Rubber grout stop plugs with an expansion rate ≥ 300% are installed at the orifice openings, forming a fully enclosed system.

[0066] Grouting operations are precisely controlled in three stages: S2-1, Filling period: Pressure 0.3–0.5 MPa, flow rate 40–60 L / min, to expand the membrane bag to 90% of the design volume; S2-2, Compacting period: Pressure 0.5–0.8 MPa, flow rate 20–30 L / min, to remove residual air and free water from the bag; S2-3, Stabilization period: Peak pressure 1.0 MPa, flow rate 5–10 L / min, maintained for 5–10 min to form dense stone body.

[0067] The grouting process in this embodiment adopts a "bottom-up, intermittent skip-hole" sequence, with dual pumps working alternately to avoid single-point overpressure. Compared with traditional processes, the grout loss rate of this system is reduced from 30% to less than 5%, cement consumption is reduced by 40%, and single-cycle operation time is shortened by more than 30%. It has been successfully applied to a high-velocity dynamic water environment of 4.5 m / s, with the membrane bag deployment rate remaining stable at over 95%. This provides a reliable, economical, and green technical approach for the treatment of high-pressure water inrush in karst tunnels.

[0068] It should be noted that if the membrane bag is damaged during the above construction process, it can be quickly repaired. Specifically, this can be done by injecting quick-setting paste (gel time ≤ 1 min) for temporary repair, or by applying an aramid reinforcing fabric (300g / m²). 2 Then, epoxy resin is used to fill the crack for permanent repair.

[0069] (3) Ordinary cement grouting is applied to the remaining gaps of the secondary waterstop to form a tertiary reinforcement layer.

[0070] Specifically, the conventional quick-setting paste grouting in this embodiment adopts a two-liquid grout system. Liquid A is a pure cement grout (d50=8μm), and liquid B is an additive (tackifier and foaming agent). The gelation time is controllable within the range of 30s to 10min.

[0071] After the construction is completed, the construction effect is tested and evaluated. The specific process is as follows: Core drilling was carried out, with a core recovery rate of ≥80% and a core RQD value of ≥75.

[0072] A water permeability test was conducted, and the permeability q ≤ 1 Lu.

[0073] After testing and evaluation, the steel pipe grating skeleton in this embodiment, as the primary support, has a moment of inertia of I = π(D⁴ - d⁴) / 64 = 1.73 × 10⁵ mm⁴ (D = 76 mm, t = 8 mm), which can withstand a surrounding rock pressure of 1.5 MPa; the membrane bag grouting forms a secondary water-stopping system with a permeability coefficient < 1 × 10⁻⁶. -7 cm / s; conventional grouting, as a three-level filler, has a diffusion radius of 3-5m. The three elements achieve coordinated deformation through interfacial shear stress τ=μσn (μ=0.65, σn=2MPa), and the overall structural safety factor K=2.8, which is lower than the standard requirement of 1.5.

[0074] The water-blocking system obtained after construction in this embodiment has a water-blocking rate of more than 95%, which significantly reduces the risk of water leakage during tunnel operation, effectively improves the durability of the project, and ensures the long-term stable operation of transportation infrastructure.

[0075] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A construction method for staged sealing of flowing water channels, characterized in that, Includes the following steps: S1. A steel pipe grid frame is placed in the water channel in a direction perpendicular to the water flow to form a primary water stop. S2. Multiple water-permeable but grout-impermeable membrane bags are installed on the water-facing side of the steel pipe grid frame, and cement grout is injected into each membrane bag. After the membrane bag and cement grout have solidified, a secondary waterstop is formed. S3. Ordinary cement grouting is performed on the remaining gaps between the multiple membrane bags to form a three-level reinforcement layer.

2. The construction method for graded sealing of flowing water channels according to claim 1, characterized in that, The steel pipe grating frame is composed of multiple steel pipes with a diameter of 70-80 mm and a wall thickness of 6-10 mm, arranged at a center distance of 150-250 mm.

3. The construction method for staged sealing of flowing water channels according to claim 1, characterized in that, The density of the membrane bag fabric is 250-350 g / m³. 2 The equivalent aperture O90 is 0.06-0.08 mm, and the tensile strength is greater than or equal to 45 kN / m.

4. The construction method for graded sealing of flowing water channels according to claim 3, characterized in that, The membrane bag is double-layered, with an outer layer of polypropylene woven fabric and an inner layer of polyester nonwoven fabric.

5. The construction method for staged sealing of flowing water channels according to claim 1, characterized in that, The cement paste is a neat cement paste, and its components include P.O42.5 cement, ultrafine mineral powder, silica fume, polycarboxylate superplasticizer and water.

6. The construction method for graded sealing of flowing water channels according to claim 1, characterized in that, The cement paste is a modified paste, and its components include P.O42.5 cement, ultrafine mineral powder, silica fume, polycarboxylate superplasticizer, water, and also aluminum sulfate-based quick-setting agent and cellulose ether anti-dispersant.

7. The construction method for graded sealing of flowing water channels according to claim 6, characterized in that, In step S2, the modified paste is injected in a bottom-up, skip-hole sequence. During the injection process, the unfolding rate of the membrane bag is monitored in real time to ensure that the unfolding rate of the membrane bag is greater than or equal to 95% under the condition that the high flow rate during injection is less than or equal to 5 m / s.

8. The construction method for graded sealing of flowing water channels according to claim 7, characterized in that, The injection of modified paste includes the following steps: S2-1, Grouting during the filling period: Grouting is carried out at a pressure of 0.3~0.5MPa and a flow rate of 40~60L / min until the membrane bag expands to 90% of the design volume; S2-2, Grouting during the compaction stage: Use a grouting pressure of 0.5~0.8MPa and a flow rate of 20~30L / min to inject grout and remove residual air and water; S2-3, Grouting during the stabilization period: Grouting is carried out at a pressure of 1.0 MPa and a flow rate of 5-10 L / min to form a dense stone body.

9. A construction method for graded sealing of a flowing water channel according to any one of claims 1-8, characterized in that, Before step S1, the flow velocity v of the flowing water in the water channel is detected in real time, and the construction method is determined based on the flow velocity v. The determination method is as follows: When the dynamic water flow velocity v is less than 2 m / s, proceed directly to step S2; When the dynamic water flow velocity is greater than or equal to 2 m / s, step S1 is executed first, followed by steps S2 and S3 in sequence.

10. A construction system for implementing the method according to any one of claims 1-9, characterized in that, include: The steel pipe grid frame, the membrane bag, the cement slurry, and the ordinary cement; also includes a positioning and lowering device, an intelligent grouting pump station, and a monitoring system, the monitoring system being used to collect flow velocity, pressure, and flow rate.

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