Tunnel reinforcing double-liquid grout and intelligent grouting control method

Abstract

The invention discloses tunnel reinforcing double-liquid grout and an intelligent grouting control method, the tunnel reinforcing double-liquid grout comprises a liquid A and a liquid B. The liquid A is a mixed liquid of bentonite and water, the volume ratio of the bentonite to the water is (380-420): (800-825), the liquid B is a mixed liquid of water glass and water, the volume ratio of the water glass to the water is (0.9-1.1): 1, and the volume ratio of the water glass to the water is (0.9-1.1): 1. The volume ratio of the liquid A to the liquid B is (12.5-13): 1. The method comprises the following steps that (1) a grouting hole is reserved in a radial hole of an anterior shield of the shield tunneling machine; (2) respectively conveying the liquid A and the liquid B to a double-liquid mixing nozzle for mixing to obtain tunnel reinforcing double-liquid slurry; and (3) in the tunneling process of the shield tunneling machine, the tunnel reinforcing double-fluid slurry is grouted through the grouting holes reserved in the front shield, and the gap between the shield body and the soil body is filled. After double liquid is mixed, good water resistance and water retaining property are achieved, and water-rich stratums can be dealt with.

Description

Technical Field

[0001] This invention relates to the field of grouting technology, specifically to a dual-component grout for tunnel reinforcement and an intelligent grouting control method. Background Technology

[0002] Tunnels are engineering structures buried underground, representing a form of human utilization of underground space. Tunnels can be categorized into traffic tunnels, hydraulic tunnels, municipal tunnels, and mining tunnels, among others. The structure of a tunnel comprises two parts: the main structure and auxiliary equipment. The main structure consists of the tunnel body and portals; auxiliary equipment includes passing bays, fire-fighting facilities, emergency communication systems, and drainage systems. Some tunnels also have specialized ventilation and lighting equipment. Existing tunnel reinforcing liquids are all single-component liquids. These single-component liquids mainly consist of cement, fly ash, and sand, and their water resistance and water-retaining properties are relatively weak. Therefore, a new reinforcing liquid is needed to enhance its water resistance. Summary of the Invention

[0003] The purpose of this invention is to provide a tunnel reinforcement dual-liquid grout and an intelligent grouting control method, which has excellent water resistance and water-retaining properties after the dual-liquid mixture is used to deal with water-rich strata.

[0004] In one aspect of the invention, a tunnel reinforcement two-component grout is proposed. According to an embodiment of the invention, it comprises a liquid A and a liquid B, wherein liquid A is a mixture of bentonite and water, the volume ratio of bentonite to water being (380-420):(800-825), liquid B is a mixture of water glass and water, the volume ratio of water glass to water being (0.9-1.1):1, and the volume ratio of liquid A to liquid B is (12.5-13):1.

[0005] In another aspect, the present invention proposes an intelligent grouting control method for a dual-component grout for tunnel reinforcement. According to an embodiment of the present invention, the method includes the following steps:

[0006] (1) Grouting holes are reserved in the radial holes of the shield at the front of the tunnel boring machine;

[0007] (2) Liquid A and liquid B are respectively transported to the two-liquid mixing nozzle for mixing to obtain the tunnel reinforcement two-liquid slurry;

[0008] (3) During the tunnel boring machine excavation process, the tunnel reinforcement double liquid grout is injected through the grouting hole reserved on the front shield to fill the gap between the shield body and the soil.

[0009] In addition, the intelligent grouting control method for tunnel reinforcement dual-liquid grout according to the above embodiments of the present invention may also have the following additional technical features:

[0010] In some embodiments of the present invention, in step (1), a valve is provided on the grouting hole.

[0011] In some embodiments of the present invention, in step (2), the viscosity of the tunnel reinforcement two-component grout is 300-500 dPa·s.

[0012] In some embodiments of the present invention, in step (2), liquid A and liquid B are delivered using different hose squeeze pumps.

[0013] In some embodiments of the present invention, in step (3), 0.5m of grout is injected per ring through the reserved grouting holes. 3 / (143% of theoretical value) of tunnel reinforcement two-component grout.

[0014] In some embodiments of the present invention, in step (3), the tunnel boring machine is excavating at a speed of 30 to 40 mm / min.

[0015] Compared with the prior art, the beneficial effects of the present invention are:

[0016] 1) The solidification time of the two-liquid mixture reaction is 6s to 20s; the strength never changes after the mixture is completed.

[0017] 2) The single liquid has good fluidity before mixing, and will not clog the pipes during long-distance pumping. It does not require cleaning the pipeline for each loop, making construction convenient.

[0018] 3) The viscosity after mixing can reach 300-500 dPa·s.

[0019] 4) The two-component mixture has excellent water resistance and water-blocking properties, making it suitable for water-rich formations.

[0020] 5) It has high load-bearing capacity and resistance to subsidence, and its volume is not easily compressed.

[0021] 6) The principle of special grout injection is to inject special grout into the outer wall of the shield through the radial holes on the shield machine during tunneling. This fills the gap formed between the cutterhead excavation space and the shield body in a timely manner, ensuring the stability of the soil above the shield body. This reduces the risk of natural soil subsidence caused by the disturbance of the shield tunneling in the third stage and subsequent settlement during construction. Attached Figure Description

[0022] Figure 1 This is a diagram showing the settlement stages during construction in Embodiment 2 of the present invention;

[0023] Figure 2 This is a schematic diagram of the slurry injection points in Embodiment 3 of the present invention;

[0024] Figure 3 This is a flowchart of the tunnel reinforcement dual-liquid grout injection process in Embodiment 3 of the present invention. Detailed Implementation

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

[0026] Example 1

[0027] This embodiment takes the 3rd platform and 8 tracks of Shushan East Station on Hefei Metro Line 6 as an example. The grout used for synchronous grouting of the shield tunnel is a hardenable grout, with raw materials mainly consisting of bentonite (sodium-based), fly ash (Grade I), medium-coarse sand, cement (P.O42.5), and water. This grout has advantages such as good long-term stability and fluidity, appropriate initial setting time, good filling performance, low dilution rate, and small consolidation volume shrinkage; it can achieve a good match between filling performance, fluidity, and consolidation strength. Synchronous grouting strictly follows the six-character principle of "synchronous, uniform, and sufficient quantity." Synchronous grouting control is strengthened by adopting a dual control standard of grouting pressure and grouting volume.

[0028] A method for simultaneous grouting in tunnels includes the following steps:

[0029] 1. Synchronous grouting

[0030] (1) Grouting pressure

[0031] When the grouting pressure is equivalent to the ground stress at the tunnel depth, the effect on reducing ground loss and surface settlement is most significant.

[0032] Subway tunnels are generally buried at depths of 10–20 meters, and the earth pressure calculations are performed using Terzaghi's method.

[0033]

[0034]

[0035] In the formula, —Earth pressure (KN / m) 2 D—outer diameter of the tunnel (m), 2B—loose ring width at the top of the tunnel (m). — The ratio of horizontal earth pressure to vertical earth pressure, γ — The unit weight of the soil (kN / m³) 3 C—cohesion of soil (KPa). —Internal friction angle of soil (°), H—Soil cover depth (m). —Ground load (kPa)

[0036] Therefore, the grouting pressure should be at least greater than .

[0037] Based on the actual conditions of this project and the above analysis, the shield tunnel top burial depth for the 3rd platform and 8th track of Shushan East Station on Hefei Metro Line 6 is 20.62m, resulting in a corresponding grouting pressure range of 0.1MPa~0.2MPa. According to the construction experience of Hefei Metro Lines 1, 2, 3, and 4, controlling the grouting pressure between 0.1 and 0.2MPa can achieve good grouting results. The specific pressure will be controlled according to the actual conditions during tunneling.

[0038] (2) Grouting volume

[0039] The determination of the grouting volume is based on the void volume of the shield tail structure, combined with the geological strata, track alignment, and tunneling method, considering an appropriate fullness coefficient to ensure dense filling. According to actual construction experience, the fullness coefficient here includes the compaction coefficient generated by grouting pressure, the soil quality coefficient depending on geological conditions, the construction consumption coefficient, and the over-excavation coefficient generated by the tunneling method. Based on the construction experience of Hefei Metro Lines 1, 2, 3, and 4, the fullness coefficient in clay layers is 1.1–1.3.

[0040] Grouting volume per ring (1.5m):

[0041]

[0042] In the formula: —Theoretical excavation radius —Outer diameter of the tunnel segment, m—Stroke length — Filling coefficient, Q— Grouting volume.

[0043] Based on the actual conditions of this underpass at Shushan East Station, the travel length is taken as 1.5m, and the filling coefficient can be taken as 1.3. The calculation results are as follows:

[0044] The grouting volume for the left line is Q = 1.3 × 1.5 × π (6.48). 2 -6.2 2 ) / 4=5.43m 3 ;

[0045] The grouting volume for the right line is Q = 1.3 × 1.5 × π (6.28). 2 -6 2 ) / 4=5.26m 3 .

[0046] Therefore, during tunnel boring machine (TBM) advancement, the grouting volume for each stroke (1.5m) should be controlled at 5.43m on the left side. 3 The right line should be controlled at 5.26m. 3 .

[0047] (3) Grouting speed

[0048] In actual construction, the injection rate is used to control the grouting volume. Therefore, the injection rate is calculated based on the injection volume per ring and the advance time per stroke, as shown in the following formula.

[0049] v=Q / t

[0050] Where: v—injection velocity (m) 3 / s), Q—Grouting volume per ring (m³) 3 ), t—time per stroke (s).

[0051] Based on the above grouting volume and the advance time per stroke, the injection speed is calculated to be between 1.17 and 1.76 L / s.

[0052] (4) Grouting mix ratio

[0053] Strict control must be exercised over the amount and quality of synchronous grouting. During shield tunneling across railways, synchronous grouting must be timely, uniform, and sufficient to ensure timely and adequate filling of structural gaps, minimizing ground deformation and segment displacement. Based on surface monitoring feedback data, effective measures should be taken promptly to control the grouting process, adjusting the grout mix ratio. Dedicated personnel should be assigned to oversee the process, meticulously recording the injection location, injection volume, and pressure values, and making timely adjustments based on ground deformation monitoring information to ensure the quality of the grouting procedure. The synchronous grout mix ratio is shown in the table below:

[0054] Table 1. Mix proportions of grouting slurry for synchronous grouting (1m) 3 )

[0055] Content per cubic meter of mortar Cement (kg) Fly ash (kg) Bentonite (kg) Medium-coarse sand (kg) Water (kg) 1m³ 150 300 70 480 375

[0056] The performance indicators of the grouting raw materials are shown in the table below:

[0057] Table 2 Performance Indicators of Slurry Raw Materials

[0058] Material Name Performance indicators fly ash Level II medium and coarse sand medium and coarse sand water tap water cement P.O42.5 grade Portland cement

[0059] (5) Performance indicators of synchronous grouting slurry

[0060] The slump is the main management indicator for the slurry, while consistency, setting time, and compressive strength of slurry test blocks are also taken into account. Based on comprehensive test data and analysis, the basic performance indicators of the rigid slurry are shown in the table.

[0061] Table 3 Slurry Performance Indicators

[0062] name Performance indicators Consistency 10~11cm Condensation time 3～5h compressive strength R7 = 1.2 MPa; R28 > 3.6 MPa

[0063] 2. Secondary grouting

[0064] To further ensure that ground settlement is within a controlled range, additional grouting holes are added to the tunnel segments under the railway, based on synchronous grouting. This increases the grouting volume, flexibility, and efficiency of secondary grouting, thereby reducing ground settlement. Secondary grouting uses single-component grout (double-component grout is used in special cases such as large water volume or significant segment uplift). The grouting location can be selected within 8-12 rings of the segment emerging from the shield tail. The grouting pressure is controlled at 0.2-0.4 MPa. A water-stop ring is installed every 10-15 rings to effectively isolate the water flow channels before and after the tunnel segments and also to fix them in place.

[0065] Before crossing, a thorough mechanical and piping inspection of the secondary grouting system is conducted, and grouting materials are stockpiled in advance, ensuring adequate grouting personnel are available. During secondary grouting, a designated person must be responsible for meticulous recording of the grouting location, volume, and pressure value. Grouting parameters must be adjusted promptly based on ground settlement monitoring data to control ground settlement and ensure railway safety. After crossing, continued monitoring continues, with timely replenishment of grout to prevent subsequent settlement. Sufficient grease must be injected into the shield tail to ensure a tight seal.

[0066] Table 4 Mix proportions of secondary grouting slurry

[0067] Content per cubic meter of mortar Cement (kg) Water (kg) Water glass (kg) 1m³ 416 366 456

[0068] 3. Porous injection-enhanced segments

[0069] Within the railway-affected area, the right line (rings 226-303) and left line (rings 227-303) are designed with multi-hole grouting type segments, and if necessary, reinforced grouting is adopted to stabilize tunnel and ground settlement.

[0070] Example 2

[0071] A tunnel reinforcement dual-liquid grout includes liquid A and liquid B. Liquid A is a mixture of bentonite and water with a volume ratio of 400:825. Liquid B is a mixture of water glass and water with a volume ratio of 1:1. The volume ratio of liquid A to liquid B is 12.5:1.

[0072] Settlement stage diagram during construction as shown below Figure 1 As shown, liquid A and liquid B are mixed in a volume ratio of 12.5:1 to form a high-viscosity, plastic, supportive, and water-repellent gel. This gel is then injected into the shield during the tunneling process to fill the gap between the shield and the soil, effectively controlling the third-stage settlement caused by the shield's advancement and assisting in the fourth-stage settlement control.

[0073] Example 3

[0074] To effectively reduce settlement at the middle and front shield sections during tunnel boring machine (TBM) excavation, a special grout is injected simultaneously during the underpass excavation. An intelligent grouting control method for a dual-component tunnel reinforcement grout includes the following steps:

[0075] (1) Grouting holes are pre-reserved in the radial holes of the shield at the front of the tunnel boring machine. Based on past experience, such as Figure 2 As shown, the grouting holes can be set at any point between 11 o'clock and 1 o'clock (clockwise) on the tunnel boring machine to ensure that the upper 2 / 3 of the circle is filled densely.

[0076] (2) Liquid A and liquid B are respectively transported to the two-liquid mixing nozzle for mixing to obtain the tunnel reinforcement two-liquid slurry;

[0077] (3) During the tunnel boring machine excavation process, the tunnel reinforcement double liquid grout is injected through the grouting hole reserved on the front shield to fill the gap between the shield body and the soil.

[0078] Based on the shield tunneling parameters, hydrogeological risks, and past construction experience, the tunnel will primarily traverse silty clay and silty clay layers during the underpass. The injection of a special grout needs to both fill the gap between the excavation face and the shield body and minimize its impact on the strata. During the tunnel boring machine's excavation, within a 30m radius along the longitudinal direction of the railway line, 0.5m of grout will be injected per ring through pre-reserved grouting holes equipped with valves on the front shield. 3 A special grout, representing 143% of the theoretical value, is used to fill the gap between the shield and the soil, controlling the ground loss rate.

[0079] Due to the characteristics of this construction method, appropriate injection equipment must be selected to achieve good construction results. For example, the injection volumes of liquids A and B differ significantly, requiring precise injection ratios; the mixture has high viscosity, necessitating precise and rapidly adjustable injection volumes; and the selected equipment must be compact, portable, and occupy minimal space within the tunnel boring machine. Based on these factors, two independently frequency-controlled hose extrusion pumps were selected, equipped with agitators, mixers, electronic flow meters, pressure gauges, and other equipment.

[0080] Motor power: Pump A motor 4.0kw, Pump B motor 1.1kw, Mixer motor 4.0kw×2.

[0081] At the start of each ring excavation, liquids A and B are injected, and the initial setting time and setting effect are checked through the check valve of the concrete mixer to ensure that the gap between the shield and the soil is filled in a timely and effective manner. The process is shown in Figure 3.

[0082] Because the synchronous grouting and follow-up grouting during shield tunneling cannot fundamentally guarantee the bearing capacity of the soil behind the segments, the segments will shift outwards from the curve after bearing lateral pressure. To ensure that the final deviation of the tunnel axis is controlled within the allowable range specified in the code, a certain offset is reserved for the tunnel during shield tunneling. Based on a comprehensive analysis of theoretical calculations and relevant construction experience, and taking into account the geological conditions of the tunneling area, a pre-offset of 10-20mm will be set during the tunneling of semi-circular curves. The pre-offset will be adjusted appropriately during construction by monitoring the tunnel offset in the radius section.

[0083] (4) Strictly control the tunnel boring machine's advance speed.

[0084] The tunnel boring machine (TBM) should be pushed forward at a speed of 30–40 mm / min. This is to avoid increasing lateral pressure due to excessive thrust and to minimize disturbance to the surrounding soil during the tunnel boring machine's advance.

[0085] (5) Strictly control the balance pressure at the front of the shield.

[0086] During tunnel boring machine (TBM) crossing, the earth pressure at the cut must be strictly controlled to ensure a slight heave (0.5–1 mm) in the strata at the cut to balance the ground settlement caused by the TBM carrying soil. Simultaneously, construction parameters related to the cut pressure balance must be strictly controlled, such as excavated soil volume, advance speed, total thrust, and the difference between the actual earth pressure and the set earth pressure. Excessive over-excavation and under-excavation must be prevented, and fluctuations in the balance pressure should be minimized, ideally controlled within 0.02 MPa.

[0087] (6) Strictly control the synchronous grouting volume and grout quality.

[0088] Due to the increased ground loss and correction frequency caused by curved sections, soil disturbance is amplified. Therefore, strict control of synchronous grouting volume and grout quality is crucial during curved section advancement. A coordinated approach of advancement and grouting should be employed to ensure adequate grouting for each ring, uniform and appropriate grouting during each tunnel advance, and adherence to quality standards for grout mix proportions. Synchronous grouting promptly fills voids in the structure, reducing soil deformation during construction. If grouting requirements are not met, tunneling should be paused to prevent soil deformation.

[0089] (7) Strictly control the deviation amount

[0090] The tunnel boring machine's (TBM) advancement along a curved path essentially occurs on the tangent of the curve. The key to this advancement is maintaining control of the TBM's head. Since each segment of the TBM undergoes correction during curved advancement, frequent measurements and adjustments are necessary, with each correction being as small as possible to ensure the wedge-shaped blocks remain within the radial-vertical plane of the radius of curvature. Besides adjusting the correction amount at selected points, wedge-shaped low-pressure cotton rubber sheets are used for segment correction when appropriate, effectively controlling the axis and ground deformation. The correction amount during TBM advancement is controlled within 5mm / m.

[0091] For the correction amount of each ring, the stroke difference between the left and right jacks of the tunnel boring machine (TBM) is calculated, and the correction amount is controlled by utilizing this stroke difference. At the same time, the tail clearance is closely monitored, and timely and appropriate adjustments are made when the clearance is unsatisfactory.

[0092] The above description is merely an example and illustration of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described, or use similar methods to replace them, as long as they do not deviate from the structure of the present invention or exceed the scope defined in the claims, all of which should fall within the protection scope of the present invention.

Claims

1. A tunnel reinforcement two-component grout, characterized in that: It includes liquid A and liquid B. Liquid A is a mixture of bentonite and water, with a volume ratio of bentonite to water of (380-420):(800-825). Liquid B is a mixture of water glass and water, with a volume ratio of water glass to water of (0.9-1.1):

1. The volume ratio of liquid A to liquid B is (12.5-13):

1.

2. A smart grouting control method for tunnel reinforcement dual-liquid grout as described in claim 1, characterized in that, Includes the following steps: (1) Grouting holes are reserved in the radial holes of the shield at the front of the tunnel boring machine; (2) Liquid A and liquid B are respectively transported to the two-liquid mixing nozzle for mixing to obtain the tunnel reinforcement two-liquid slurry; (3) During the tunnel boring machine excavation process, the tunnel reinforcement double liquid grout is injected through the grouting hole reserved on the front shield to fill the gap between the shield body and the soil.

3. The intelligent grouting control method for a dual-component grout for tunnel reinforcement according to claim 2, characterized in that: In step (1), a valve is provided on the grouting hole.

4. The intelligent grouting control method for a dual-component grout for tunnel reinforcement according to claim 2, characterized in that: In step (2), the viscosity of the tunnel reinforcement two-component grout is 300-500 dPa·s.

5. The intelligent grouting control method for a dual-component grout for tunnel reinforcement according to claim 2, characterized in that: In step (2), liquid A and liquid B are transported using different hose squeeze pumps.

6. The intelligent grouting control method for a dual-component grout for tunnel reinforcement according to claim 2, characterized in that: In step (3), 0.5m of grout is injected per ring through the pre-reserved grouting holes. 3 / (143% of theoretical value) of tunnel reinforcement two-component grout.

7. The intelligent grouting control method for a dual-component grout for tunnel reinforcement according to claim 2, characterized in that: In step (3), the tunnel boring machine is excavating at a speed of 30-40 mm / min.

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