Bag type synchronous grouting method for shield tunnel

Abstract

The invention discloses a shield tunnel capsular bag type synchronous grouting method which comprises the following steps that S1, a shield tunneling machine splices an annular pipe piece in a soil layer, the side wall of the pipe piece is provided with a plurality of grouting holes, the outer wall of the pipe piece is provided with a capsular bag in advance, the grouting holes comprise an inner hole and an outer hole, the inner hole is formed in an inner cavity of an inner pipe, the outer hole is formed in the space between the inner pipe and the outer pipe, and the outer hole is communicated with the inner pipe; the bag comprises a first bag body and a second bag body; and S2, grout is injected into the multiple first bag bodies through outer holes of the multiple grouting holes, the expanded bags extrude the soil layer and the pipe piece, all the grouting holes are closed, in this way, the grout is injected into all the first bag bodies to fill an annular gap between the soil layer and the pipe piece, and any two adjacent expanded bags in the circumferential direction extrude each other. The bag forms a physical barrier, grout is strictly limited in the gap between the duct piece and the soil layer, after primary grouting is completed, secondary supplementary grouting can be conducted on a detected cavity area, it is ensured that filling is full and uniform, and the cavity area is obviously reduced.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of shield tunnel construction technology, and more particularly to a bag type synchronous grouting method for shield tunnel. BACKGROUND

[0002] At present, many urban rail transit lines are opened and operated in China, and the long operating mileage of the rapidly developing metro brings great challenges to maintenance work while bringing traffic convenience to the city.

[0003] In the process of shield tunneling, in order to fill the annular gap between the segment and the surrounding soil, it is necessary to continuously grout behind the wall at a certain pressure during the advancement of the shield machine. The grouting effect is often difficult to guarantee due to many factors such as poor adaptability of synchronous grouting slurry material performance, grouting pressure, flow and filling uniformity, slurry ratio and process to variable soil layers, lack of effective in-situ and real-time quality detection means, etc. The main components of the slurry are cement, sand, fly ash, bentonite and water, and the initial setting time is long.

[0004] In water-rich soft soil, slurry loss is easy to occur, and there are phenomena of segment wall cavity area and non-compaction. Inert slurry is easy to be diluted before initial setting, and due to the fluidity of the slurry, the top slurry will concentrate at the bottom along the outer wall of the segment, and the upper space of the segment is not effectively filled. The segment is subjected to the combined action of water and slurry buoyancy, and the phenomenon of upward floating occurs.

[0005] Due to the long setting time of the slurry, under the influence of shield tunneling vibration and tunnel construction vibration, the un-solidified slurry material may be squeezed into the tunnel bottom or soil layer gap. Figure 1 The slurry of one-time grouting (the first batch of injected slurry) can be filled in the time period when the gel time and the retention time of the plastic state solidification zone overlap, but after entering the solidification zone, the solidified body does not move, so the slurry of subsequent two-time grouting (the first batch of injected slurry, or the second batch of injected slurry + the third batch of injected slurry) cannot be sequentially pressed to the unfilled position, and the unfilled position will form a cavity area, so the construction use is limited, further aggravating the upward floating of the tunnel.

[0006] In addition, no matter how advanced the traditional synchronous grouting process is, it may produce local hollow areas due to various complex working conditions (such as small-radius curves, sudden changes in soil layers). When monitoring data or geophysical detection shows that there is a hollow area behind the segment, the only traditional repair method is secondary grouting, also known as post-grouting or supplementary grouting. Secondary grouting needs to use the pre- reserved grouting hole on the segment, and the slurry injected into the soil will not accurately fill only in the hollow area. Under pressure, it will preferentially spread along the path with the smallest resistance, which causes the slurry of secondary grouting to be easily diluted or washed away by underground water, or to flow into the cracks of the surrounding soil, resulting in the hollow area possibly not being truly filled and compacted, especially the top of the hollow area. In addition, in order to make the slurry flow in, high-pressure grouting is often used, and this pressure may split the surrounding rock and soil, rather than filling the hollow area. This splitting effect will disturb the soil and even cause the slurry to surge up, causing ground uplift and damaging the road or building above. In summary, the traditional secondary grouting to fill the hollow area needs to reposition, grout, maintain, and seal the hole in the already formed tunnel, which is difficult to construct, has a long construction period, and is high in cost.

[0007] The hollow area behind the segment causes the segment to lose support, and under the action of self-weight or external load (such as underground water buoyancy), the adjacent segments produce ring or longitudinal misalignment, the hollow area causes the waterproof system to fail (such as the waterstop cannot tightly adhere), and the underground water penetrates to the segment joint through the hollow area, causing ring and longitudinal joint leakage. The uneven stress behind the segment (stress concentration at the hollow area) causes the segment to produce a through crack, especially above the ring waist (because the top hollow area is more prone to cause stress concentration), and the tunnel defects caused by the synchronous grouting itself and external conditions further accelerate the deformation of the segment beyond the limit and damage the bearing capacity of the structure, which poses a hidden danger to the long-term safety of the tunnel. SUMMARY

[0008] In view of the above defects or improvement needs of the prior art, the present application provides a bag-type synchronous grouting method for a shield tunnel, which uses bag-type grouting technology to avoid slurry loss, channeling, or dilution by underground water, resulting in incomplete filling and easy formation of hollow areas. The bag forms a physical barrier to strictly limit the slurry in the gap between the segment and the soil. After the first grouting, secondary supplementary grouting is performed on the detected hollow area to ensure full and uniform filling, significantly reducing the probability of hollow areas.

[0009] To achieve the above-mentioned purpose, according to the present application, a bag-type synchronous grouting method for a shield tunnel is provided, comprising the following steps: S1, the shield machine splices out a ring-shaped segment in the soil layer, and there is an annular gap between the soil layer and the segment, wherein the side wall of the segment has a plurality of grouting holes which are uniformly arranged in the circumferential direction, the outer wall of the segment is pre-installed with a bag at a position corresponding to each grouting hole, the grouting hole comprises an inner hole and an outer hole, the grouting hole is formed by an outer tube and an inner tube arranged in the outer tube, the inner cavity of the inner tube forms the inner hole, and the space between the inner tube and the outer tube forms the outer hole, the bag comprises a one-piece first bag body and a second bag body, the first bag body is located between the second bag body and the segment, the outer wall of the outer tube is connected to the bag opening of the first bag body, the inner tube extends into the first bag body, and the outer wall of the inner tube is connected to the bag opening of the second bag body; S2, inject slurry into the plurality of first bag bodies through the outer holes of the plurality of grouting holes to inflate the bag, and the inflated bag extrudes the soil layer and the segment, then close all the grouting holes that have been grouted, in this way, slurry is injected into all the first bag bodies to fill the annular gap between the soil layer and the segment, and any two adjacent inflated bags in the circumferential direction extrude each other.

[0010] Preferably, it further comprises: S3, use the shield grouting monitor to detect the hollow area outside the bag, then inject slurry into the second bag through the inner hole of the grouting hole to fill the hollow area.

[0011] Preferably, steps S2 and S3 further comprise controllable field digital tracking grouting: collect the grouting pressure in the bag through the pressure sensor, collect the flow rate in the bag in real time through the flow meter, and collect the inflation amount of the bag and the deformation data of the soil layer around the bag in real time through the displacement sensor, so as to adjust the grouting pressure and the amount of slurry injected into the bag in real time through the intelligent control module, so as to realize accurate filling of the gap behind the segment wall and prevent attitude deviation caused by uneven slurry diffusion.

[0012] Preferably, draw a grouting pressure-time-slurry amount curve according to the obtained grouting pressure and slurry amount in real time to judge the filling condition of the annular gap, and evaluate the grouting effect through ultrasonic detection at the top of the segment and ground settlement monitoring at the bottom of the segment, so as to supplement the grouting of the bag.

[0013] Preferably, in step S2, adjust the extrusion force acting on the outer wall of the segment by adjusting the grouting pressure and slurry flow rate in real time, so as to realize accurate control of the attitude of the segment.

[0014] Preferably, in step S2, after the initial setting of the slurry in the first bag body, it is judged whether to grout the second bag body of the bag according to the hollow detection data.

[0015] Preferably, in step S2, the grouting is simultaneously performed at two grouting holes or four grouting holes, and the simultaneously grouting holes are evenly distributed in the circumferential direction.

[0016] Preferably, in step S1, the bag skin of the bladder comprises three nitrile rubber layers and two nylon cloth layers, and they are alternately arranged, and the bag skin of the bladder is prepared by a laminating process, wherein: The tensile strength of the single-layer nylon cloth is ≥ 272 daN / 5 cm, and the tensile strength of the bag skin of the bladder is ≥ 300 daN / 5 cm; The thickness of the bag skin of the bladder is 1.5 mm to 2.5 mm, wherein the thickness of the rubber layer is 0.4 mm to 1 mm, and the thickness of the nylon cloth layer is 0.1 mm to 0.3 mm; The working temperature of the bladder is -30℃ to 100℃; The air permeability coefficient of the nitrile rubber layer is ≤ 0.01 cm 3 / (cm·s·cmHg).

[0017] Preferably, in step S2, the components of the slurry include lime, fly ash, medium-fine sand, bentonite, water and water reducing agent, and: The lime is slaked lime, the calcium hydroxide content of the lime is ≥ 85%, and the 320-mesh sieve residue amount is ≤ 0.5%; The fineness grade of the fly ash is grade II, and the 0.045 mm square hole sieve residue amount is ≤ 20%; The medium-fine sand uses river sand, the fineness modulus is 1.8 to 2.2, and the clay content is ≤ 3%; The 200-mesh sieve residue amount of the bentonite is ≤ 5%, and the swelling rate is 18 mL / g to 30 mL / g; The density of the water reducing agent at 20℃ is 1.06±0.01 g / cm 3 , and the water reducing rate is 20% to 30%; The performance indicators of the slurry are as follows: permeability ≤ 5×10 -5 cm / s, specific gravity ≥ 1.80 g / cm 3 , slump degree is 12 cm to 16 cm, 20h slump degree change ≥ 5 cm, compressive strength after 3 days of solidification ≥ 0.10 MPa, compressive strength after 7 days of solidification ≥ 0.15 MPa, compressive strength after 28 days of solidification ≥ 1.0 MPa, consolidation shrinkage rate ≤ 5%, expansion rate ≥ 0.02%, bleeding rate ≤ 0.3%, and initial setting time is 3h to 10h.

[0018] Preferably, in step S2, the grouting pressure when grouting is 1.1 to 1.2 times the static water and soil pressure, and the volume of the slurry in all the bladders is 1.5 to 2.5 times the volume of the annular gap.

[0019] Overall, compared with the prior art, the above technical solutions conceived by the present application can achieve the following beneficial effects: 1) The bag type synchronous grouting method for shield tunneling of the present application strictly confines the slurry in the predetermined range of the shield tail gap, completely eliminates the possibility of dilution of the slurry by underground water or escape of the slurry to the surrounding soil, ensures that the water-cement ratio and performance of the slurry remain stable before setting, and guarantees the final strength and quality of the grouting body.

[0020] 2) The bag type synchronous grouting method for shield tunneling of the present application, after grouting of all the first bag bodies, the circumferentially adjacent two expanded bag bodies are pressed against each other, and all the first bag bodies together form a complete, gapless and constrained support ring to support the segment.

[0021] 3) The bag type synchronous grouting method for shield tunneling of the present application, when the first bag bodies expand, they will exert pressure on the soil and the segment. This active and uniform support force applied when the segment is extruded out of the shield tail can effectively inhibit and prevent the segment from floating, sinking or deviating, greatly improving the quality of tunnel forming.

[0022] 4) The bag type synchronous grouting method for shield tunneling of the present application, after the shield grouting monitor detects the cavity area, without any drilling or damage to the segment, the operator only needs to connect to the pre-set inner hole to accurately inject the slurry into the second bag body located outside the first bag body (closer to the soil), which is specially used to fill the cavity area that the first bag body cannot completely fill. The first bag body completes most of the synchronous grouting task, while the second bag body plays the role of insurance and fine adjustment, realizing secondary deviation correction. This design structurally reserves repair means, changes the destructive secondary repair in traditional shield construction into non-destructive accurate reinforcement, which is a major optimization of the shield grouting process. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 A schematic diagram of multiple grouting in the soil in the prior art; Figure 2 A process flow diagram of the present application; Figure 3 A schematic diagram of the formation of a grouting hole by the outer tube and the inner tube and the structure around the grouting hole in the present application; Figure 4 A schematic diagram of the inflation of a single bag on the segment in the present application; Figure 5 A schematic diagram of the initial state of a single bag pre-installed on the segment in the present application; Figure 6 A schematic diagram of a single bag after one grouting in the present application; Figure 7A schematic view of secondary grouting for a single bag of the present application; Figure 8 A schematic view of a bag extruding a pipe segment and soil after secondary grouting; Figure 9 A schematic view of secondary grouting for a bag on two pipe segments; Figure 10 A schematic view of a bag covering a joint of pipe segments after secondary grouting; In all the drawings, the same reference signs refer to the same technical features, in particular: 1, pipe segment; 2, primary grouting reinforcement; 3, secondary grouting reinforcement; 4, bag; 11, anchor; 12, water stop; 41, first bag body; 42, second bag body; 5, grouting hole; 51, outer tube; 52, inner tube; 6, grouting cavity; 7, soil. DETAILED DESCRIPTION

[0024] In order to make the objectives, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and should not be used to limit the present application. In addition, the technical features involved in the various embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0025] Reference Figures 2-10 A shield tunnel bag synchronous grouting method, comprising the following steps: S1, the shield machine splices out the annular segment 1 in the soil layer 7, and there is an annular gap between the soil layer 7 and the segment 1, wherein the side wall of the segment 1 has a plurality of grouting holes 5 which are uniformly arranged in the circumferential direction, the grouting hole 5 is prefabricated on the arc-shaped lining of the segment 1 when the arc-shaped lining of the segment 1 is prepared (the arc-shaped lining is spliced together to form the annular segment 1), and the outer wall of the segment 1 is respectively preassembled with a bag 4 at a position corresponding to each grouting hole 5, and the bag 4 is also preassembled on the arc-shaped lining after the arc-shaped lining of the segment 1 is prepared. The grouting hole 5 includes an inner hole and an outer hole, and the grouting hole 5 is formed by an outer pipe 51 and an inner pipe 52 arranged in the outer pipe 51, the inner cavity of the inner pipe 52 forms the inner hole, and the space between the inner pipe 52 and the outer pipe 51 forms the outer hole, and the segment 1 is further provided with anchor bars 11 and water stop pieces 12 and other conventional structures outside the outer pipe 51, the bag 4 includes a first bag body 41 and a second bag body 42 which are integrally formed, the first bag body 41 and the second bag body 42 respectively have a grouting cavity 6, so that the bag 4 has two grouting cavities 6 for containing slurry, the first bag body 41 is located between the second bag body 42 and the segment 1, the outer wall of the outer pipe 51 is connected to the bag opening of the first bag body 41, the outer wall of the outer pipe 51 is preferably sealingly connected to the bag opening of the first bag body 41, the inner pipe 52 extends into the first bag body 41, and the outer wall of the inner pipe 52 is connected to the bag opening of the second bag body 42, and the outer wall of the inner pipe 52 is preferably sealingly connected to the bag opening of the second bag body 42. The bag 4 is preassembled on the outer wall of the segment 1, and after one-time grouting of the first bag body 41, subsequent secondary grouting of the second bag body 42 can be performed as needed, which reduces a large amount of manual intervention such as re-drilling and installation of equipment during secondary grouting in the later period, significantly improves construction efficiency and reduces safety risks. The two channels of the inner hole and the outer hole are completely independent, and this structure avoids the mixing and dilution of new slurry and old slurry which may be caused by traditional single-hole slurry supplementing, so that the present application can make the slurry only enter the second bag body 42 during secondary grouting, without interfering with the slurry of the first bag body 41, especially when the slurry of the first bag body 41 is initially set, the secondary grouting can be completed without damaging the base filling layer formed by one-time grouting, so as to ensure the compactness and strength of the whole filling body.

[0026] S2, injecting slurry into the plurality of first bag bodies 41 through the outer holes of the plurality of grouting holes 5 to inflate the bladder bag 4, the inflated bladder bag 4 extruding the soil layer 7 and the pipe piece 1, and then closing all the grouting holes 5 that have been grouted, in this way, the slurry is injected into all the first bag bodies 41, and any two adjacent inflated bladder bags 4 are extruded to each other in the circumferential direction; the first bag body 41 is filled with the slurry injected through the outer hole, and the inflated bladder bag 4 fills the main body area of the annular gap. The first bag body 41 serves as the main filling layer, the inflation range of which covers most of the area of the outer wall of the pipe piece 1, and the bladder bag 4 is closely attached to the pipe piece 1 and the soil layer 7, ensuring effective bonding of the slurry with the pipe piece 1 and the soil layer 7, and providing preliminary support for the tunnel. Compared with the traditional grouting filling method relying on the flow and diffusion of the slurry, the active inflation filling of the first bag body 41 is more efficient, can quickly fill the gap after the shield tunneling, and avoid the deformation of the pipe piece 1 due to long-term lack of support.

[0027] Further, after the initial setting of the slurry in the first bag body 41, it is determined whether to grout the second bag body of the bladder bag according to the cavity detection data. If the second bag body 42 of the bladder bag needs to be grouted, the following steps are performed: S3, detecting the cavity area outside the bladder bag 4 by using the shield grouting monitor, and then injecting the slurry into the second bag body 42 through the inner hole of the grouting hole 5 to fill the cavity area. First, the cavity area outside the pipe piece 1 is detected by using the shield grouting monitor, and then the slurry is injected into the second bag body 42 through the inner hole to fill the cavity area. This design breaks the limitation of traditional slurry repair, which is based on experience and blind grouting in a large area. Since the slurry in the first bag body 41 has formed a basic filling layer after the grouting in step S2, the shield grouting monitor can accurately locate the small cavity area that has not been filled (such as the joint of the pipe piece 1 and the local concave area of the soil layer 7), and the inner hole can directly deliver the slurry to the second bag body 42, so that the second bag body 42 is inflated to fill the cavity area, achieving accurate repair of the cavity area, and ensuring that there is no missed filling blind area (cavity area) in the annular gap. The slurry in the first bag body 41 forms a primary grouting reinforcement body 2, and the slurry in the second bag body 42 forms a secondary grouting reinforcement body 3.

[0028] The shield tunnel bladder bag synchronous grouting method of the present application solves the problem of traditional synchronous grouting through the physical constraint of the bladder bag 4 + layered accurate filling + uniform stress support design, which not only ensures the full filling of the annular gap and the safety of the pipe piece structure, but also improves the waterproof performance and construction economy, and is especially suitable for shield tunnel construction in complex geological conditions such as water-rich soft soil and high water pressure soil, providing reliable protection for long-term safe operation of the tunnel.

[0029] Further, step S2 and step S3 also include controllable field digital tracking grouting: collecting the grouting pressure in the bag 4 through the pressure sensor, collecting the flow in the bag 4 in real time through the flow meter, and collecting the inflation amount of the bag 4 and the deformation data of the soil layer 7 around the bag 4 in real time through the displacement sensor, so as to adjust the grouting pressure and the slurry flow in real time through the intelligent control module, realize accurate filling of the gap behind the pipe wall, and prevent attitude deviation caused by uneven diffusion of slurry.

[0030] Digital tracking grouting fundamentally changes the traditional, experience-dependent open-loop grouting operation into a real-time, data-driven, and accurately controlled closed-loop intelligent construction. The pressure sensor reflects the slurry pressure inside the bag 4, which is directly related to the extrusion force of the bag 4 on the surrounding soil layer 7 and the pipe 1. The flow meter ensures that the amount of injected slurry is accurately controllable. The displacement sensor provides the actual inflation amount of the bag 4 and its real impact on the deformation of the surrounding soil layer. This set of sensing data (pressure, flow, displacement) collectively builds a three-dimensional real-time state model, enabling operators to see the working conditions of the underground bag 4 for the first time, and converting the vague grouting filling into quantifiable construction. With the introduction of digital tracking grouting, the system becomes actively controlled, and the intelligent control module can dynamically adjust the grouting parameters during the grouting process (step S2 or step S3) based on real-time data feedback from sensors (for example, the displacement sensor shows that the inflation of the bag 4 at a certain place has reached the preset value, or the pressure sensor shows that the critical pressure of the soil layer 7 has been approached).

[0031] Through flow and displacement data, it is ensured that the bag 4 is fully inflated and effectively extrudes the soil layer 7 and the pipe 1, thereby minimizing the number of hollow areas that need to be repaired in step S3, greatly improving the success rate and filling fullness of the first grouting in step S2. Through pressure sensor monitoring, it is prevented that the grouting pressure (especially the extrusion force of the bag 4 inflation on the pipe 1) is too large, avoiding damage to the pipe 1, floating or excessive uplift of the ground surface caused by uncontrolled pressure.

[0032] Further, by adjusting the grouting pressure and slurry flow in real time and adjusting the extrusion force acting on the outer wall of the pipe 1, the attitude of the pipe 1 is accurately controlled. The intelligent control module can obtain the instantaneous attitude of the pipe 1 in real time according to the pipe 1 attitude monitoring data, and differentially control the grouting pressure and slurry amount of different bags 4 around the pipe 1.

[0033] The water and soil pressure borne by the segment 1 is highly uneven when shield tunneling, especially when passing through a small-radius curve or complex soil layers 7. In these working conditions, the risk of uncontrolled grouting is extremely high, and it is more likely to cause segment 1 to deviate and reduce the quality of shield tunneling. The present application allows the intelligent control module to apply different extrusion forces at different positions in the circumferential direction of the segment 1 by adjusting the grouting pressure and slurry volume in real time, thereby guiding or pushing the segment 1 to ensure that it is accurately positioned according to the designed curve radius and attitude. This differentiated grouting capability is a key technical guarantee for achieving high-precision molding of small-radius curve segments.

[0034] Further, by monitoring the obtained grouting pressure and slurry volume in real time, a grouting pressure-time-slurry volume curve is drawn to determine the annular gap filling condition. The grouting effect can be evaluated by ultrasonic detection at the top of the segment 1 and ground settlement monitoring at the bottom of the segment 1, so as to supplement grouting.

[0035] By monitoring the pressure and slurry volume in real time and drawing the grouting pressure-time-slurry volume curve, the present application converts the filling process of the capsule bag 4 in the underground soil layer 7 into an analyzable and visualized data model. This curve is a scientific basis for determining the annular gap filling condition. For example, in the initial stage of grouting, the pressure is stable and the flow is large, indicating that the slurry is filling the capsule bag 4 freely; when the pressure begins to rise rapidly, it indicates that the capsule bag 4 has been basically inflated and begins to extrude the soil layer 7 and the segment 1; when the pressure reaches the set value and remains stable, it indicates that the region has reached a dense filling state. By analyzing the shape of this curve, the operator can quantitatively, rather than by feeling, determine the completion quality of one grouting in step S2.

[0036] The internal parameters (from the grouting pressure-time-slurry volume curve) reflect the internal state of the capsule bag 4.

[0037] Through external detection parameters, such as ultrasonic detection at the top of the segment 1, the slurry at the top will concentrate to the bottom along the outer wall of the segment 1, and the upper gap of the segment 1 is not effectively filled. The ultrasonic wave can accurately find the small hollow area at the top, and the ground settlement monitoring at the bottom of the segment 1 can evaluate the overall impact of the grouting operation on the external environment, ensuring that the grouting pressure and inflation volume accurately control the attitude of the segment 1 while not causing excessive disturbance (such as excessive uplift or settlement) to the soil layer 7.

[0038] By combining the grouting pressure-time-slurry volume curve (internal), ultrasonic wave (top), and settlement (external), a three-dimensional and dead-angle-free quality evaluation network is constructed, ensuring high reliability of the evaluation results and avoiding blind grouting, so as to achieve precise reinforcement.

[0039] Further, in step S3, the second bag body 42 of the capsule bag 4 is grouted after the initial setting of the slurry in the first bag body 41.

[0040] The core design of the present application is the main filling of step S2 and the cavity filling of step S3. In step S2, the first bag 41 is filled with a large amount of slurry to form the main support ring. The slurry is essentially a high-density fluid with fluidity before initial setting. If step S3 is performed before the initial setting of the slurry in step S2, the slurry is injected into the second bag 42, and the pressure will act on the external soil layer 7 and the internal first bag 41 at the same time. Since the slurry in the first bag 41 has not yet set, the injection pressure of step S3 may cause the fluid slurry injected in step S2 to be squeezed out, or cause the first bag 41 to deform uncontrollably, which will cause the slurry filling pressure of step S3 to be unable to effectively act on the target cavity area, but may interfere with or even destroy the main filling layer of step S2, and even through fluid conduction of step S2, exert uneven secondary pressure on the pipe section 1. By waiting for the initial setting of the slurry in step S2, the first bag 41 is transformed from a fluid filler to a semi-solid foundation layer with initial strength and stable shape. At this time, the first bag 41 with initial setting of the slurry becomes a solid backboard or foundation for the secondary slurry filling step of step S3. When step S3 begins to inject slurry into the second bag 42, the pressure of the slurry injected in step S3 will be firmly resisted by the formed foundation layer, thereby ensuring that the slurry injection pressure of step S3 is directed to act on the external cavity area, which ensures that the slurry injection pressure of step S3 does not transmit inward to interfere with the pipe section 1, but acts outward to fill the cavity area.

[0041] If the slurry in step S2 does not wait for initial setting, the slurry in step S2 will still be in a fluid state, which will cause the cavity area itself to change dynamically. The fluid slurry may still be slowly flowing under its own gravity or soil pressure, and at this time the detected cavity area may not be in its final form. After waiting for the initial setting of the slurry in step S2, the form of the main filling layer formed in step S2 has been fixed. At this time, the cavity area detected by the monitoring instrument is real, stable and final filling defect. Based on this solidified site, step S3 is restarted to inject slurry into the second bag 42, which realizes the role of lossless precise reinforcement and insurance and fine adjustment pursued by the present application. The slurry of step S3 is accurately injected into the small blind area (such as the joint of the pipe section 1, the local depression of the soil layer 7) that step S2 cannot reach, achieving precise repair where there is a cavity area.

[0042] Further, in step S2, the injection is performed simultaneously at two injection holes 5 or four injection holes 5, and these injection holes 5 are uniformly distributed circumferentially.

[0043] One of the biggest risks of traditional grouting (even the present invention if not limited) is that the grouting pressure itself causes the segment 1 to float or deform beyond the limit due to uneven stress. Through the above multi-point simultaneous grouting, this mechanical balance design ensures that after the step S2 construction, the key stage of the capsule bag 4 expansion, extrusion of the soil layer 7 and the segment 1, the segment 1 itself will not deviate from the new attitude due to grouting construction, two or four points synchronous grouting, is to change the grouting operation of step S2 from a risk source that may cause the segment 1 to deform into a balancer and stabilizer that realizes the attitude control of the segment 1. It ensures that the main grouting step of step S2 does not disturb the attitude of the segment 1 while efficiently and uniformly filling the annular gap.

[0044] Further, in step S1, the bag skin of the capsule bag 4 includes three nitrile rubber layers and two nylon cloth layers, which are arranged alternately, and the bag skin of the capsule bag 4 is prepared by a lamination process, wherein: The tensile strength of the single-layer nylon cloth is ≥272 daN / 5 cm, and the tensile strength of the bag skin of the capsule bag 4 is ≥300 daN / 5 cm; The nylon cloth provides extremely high tensile strength and toughness as a reinforcing framework, ensuring that the capsule bag 4 will not structurally rupture or tear under high-pressure grouting. As a matrix, the two layers of nylon cloth are firmly bonded together through the lamination process, allowing them to work together to resist tension, thereby making the total strength of the composite (≥300 daN / 5 cm) exceed that of a single layer of material. This design ensures that the capsule bag 4 has the ability to withstand water and soil pressure while being filled with grout in an underground high-pressure environment.

[0045] The nitrile rubber layer as the inner and outer surface layer of the capsule bag 4 can effectively resist the long-term corrosion of these grouts and underground water, ensuring that the capsule bag 4 will not fail due to chemical degradation.

[0046] The thickness of the bag skin of the capsule bag 4 is 1.5 mm to 2.5 mm, wherein the thickness of the rubber layer is 0.4 mm to 1 mm, and the thickness of the nylon cloth layer is 0.1 mm to 0.3 mm; the thickness of 1.5 mm to 2.5 mm makes the capsule bag 4 still have good flexibility before grouting, easy to fold, transport and pre-fix on the outer wall of the segment 1, and will not bring too much inconvenience to the pre-fixing of the segment 1 in step S1. The thickness of each rubber layer can be the same or different, and the thickness of each nylon cloth layer can be the same or different.

[0047] The working temperature of the capsule bag 4 is -30℃ to 100℃; the working temperature of -30℃ to 100℃ covers from winter construction in cold regions to the temperature rise that may be caused by the hydration heat of grout, ensuring that the capsule bag 4 material can maintain its physical properties under various extreme conditions and will not become brittle or excessively soften.

[0048] The air permeability coefficient of the nitrile rubber layer is ≤0.01 cm 3 The limited extremely low air permeability coefficient directly ensures that the bag 4 has extremely high air tightness, and also ensures its liquid tightness to the slurry. This physically eliminates the loss of slurry to the soil layer 7, and also prevents the reverse infiltration of underground water into the bag 4 to dilute the slurry, which is the basis for the precise limiting effect of the present application.

[0049] The key performance parameter table of the bag 4 is shown in Table 1.

[0050] Table 1 Key performance parameter table of the bag The bag 4 of the present application adopts "three layers of nitrile rubber sandwiched between two layers of nylon cloth", which is a kind of multi-layer composite functional material. The nitrile rubber (NBR) is used as the main protective layer, and the nylon cloth (polyamide fiber) is used as the reinforcing framework. The core performance advantage lies in the synergy of the oil resistance / chemical corrosion resistance of nitrile rubber and the high strength / tensile resistance of nylon cloth, which is suitable for shield segment 1 bag 4, soft liquid storage tank, high pressure sealing element and other engineering scenarios with extremely high requirements for sealing, strength and durability.

[0051] The bag 4 of the present application adopts a symmetrical structure of "rubber layer-nylon cloth layer-rubber layer-nylon cloth layer-rubber layer", and the specific composition and performance analysis is as follows: 1. Surface layer, middle layer and bottom layer: nitrile rubber (NBR) As a protective layer for contact medium, the quality of nitrile rubber directly affects the oil resistance, chemical corrosion resistance and aging resistance of the material. According to the application scenario, ordinary nitrile rubber (NBR) or chlorinated butyl rubber (CIIR) (such as used for freon leakage prevention rubber pipe) can be selected, among which chlorinated butyl rubber has better air tightness.

[0052] 2. Interlayer: two layers of nylon cloth (polyamide fiber) As a reinforcing framework, the high toughness (elongation at break ≥150%) and tensile strength (≥80MPa) of nylon cloth can effectively improve the overall mechanical properties of the material and prevent it from tearing under high pressure or tensile load. Common nylon cloth includes PA300 nylon (high toughness polyamide) and polyester (replaces nylon in some scenarios).

[0053] 3. Application environment As a key component for filling the gap behind the segment 1 in shield construction, the bag 4 needs to withstand the groundwater pressure (0.1MPa~1.0MPa), soil pressure (0.5MPa~2MPa) and slurry corrosion (cement slurry, chemical slurry). The structure of three layers of nitrile rubber sandwiched between two layers of nylon fabric can effectively prevent the bag 4 from breaking (the tensile strength of nylon fabric ≥300daN / 5cm), and the oil resistance of nitrile rubber can resist the oil components in the slurry (such as water reducing agent in cement slurry), ensuring the grouting effect.

[0054] 4. Advantages Synergistic effect: the combination of oil resistance of nitrile rubber and high strength of nylon fabric solves the problem of "insufficient strength" of single rubber material or "poor corrosion resistance" of single fiber material.

[0055] Wide adaptability: by adjusting the type of rubber (such as chlorinated butyl rubber) and the number of nylon fabric layers (such as 3 layers of nylon), the needs of different scenarios can be met.

[0056] Good processing performance: the adhesion between rubber and nylon fabric (the polar cyano group of nitrile rubber and the amide group of nylon can form hydrogen bonds) makes the lamination process simple and low in cost.

[0057] Further, in steps S2 and S3, the components of the slurry include lime, fly ash, medium-fine sand, bentonite, water, and water reducing agent, and: The lime is slaked lime, the calcium hydroxide content of the lime is ≥85%, and the 320 mesh sieve residue amount is ≤0.5%; The fly ash has a fineness grade of grade II, and the 0.045mm square hole sieve residue amount is ≤20%; The medium-fine sand uses river sand, the fineness modulus is 1.8~2.2, and the clay content is ≤3%; The bentonite has a 200 mesh sieve residue amount of ≤5% and an expansion rate of 18mL / g~30mL / g; The water reducing agent has a density of 1.06±0.01g / cm 3 at 20℃, and a water reducing rate of 20%~30%; The performance indicators of the slurry are as follows: the permeability coefficient is ≤5×10 -5 cm / s, the specific gravity is ≥1.80g / cm 3 , the slump degree is 12cm~16cm, the 20h slump degree change is ≥5cm, the compressive strength after 3 days of solidification is ≥0.10MPa, the compressive strength after 7 days of solidification is ≥0.15MPa, the compressive strength after 28 days of solidification is ≥1.0MPa, the consolidation shrinkage rate is ≤5%, the expansion rate is ≥0.02%, the bleeding rate is ≤0.3%, and the initial setting time is 3h~10h.

[0058] The main performance parameters of the slurry and the parameters of the raw materials are shown in Tables 2 and 3.

[0059] Table 2 Main technical indicators of slurry Table 3 Slurry composition raw material table The calcium hydroxide content of the slaked lime is ≥85% and the 320 mesh sieve residue amount is ≤0.5%, the high-purity active ingredient ensures the sufficiency of the slurry gelation reaction, reduces the influence of inert impurities on the consolidation strength, and provides a core guarantee for early strength formation; the 0.045 mm square hole sieve residue amount of the grade II fly ash is ≤20%, the fine particles can fill the voids of medium-fine sand to form a dense skeleton structure, and at the same time, the pozzolanic effect is played to react with the lime hydration product to generate additional cementitious material, improving the compactness and durability of the slurry after consolidation. The medium-fine sand selects river sand with a fineness modulus of 1.8-2.2 and a clay content of ≤3%, which not only ensures the skeleton strength of the slurry, but also avoids the absorption of soil particles to water, hinders the hydration reaction, and effectively prevents the strength decay of the consolidated body; the 200 mesh sieve residue amount of the bentonite is ≤5% and the swelling rate is 18 mL / g-30 mL / g, which forms a stable colloid structure in the slurry, significantly improves the water retention and water dispersion resistance of the slurry, and cooperates with the water-reducing agent with a water-reducing rate of 20%-30% to reduce the water consumption while ensuring the fluidity of the slurry, solving the contradiction between the fluidity and strength of the traditional slurry. The precise matching of each component enables the slurry to maintain stable performance in the whole stage of stirring, pumping, filling and consolidation, providing a fundamental guarantee for the subsequent filling quality from the material level.

[0060] The strict limitation of 12 key performance indicators such as permeability, specific gravity, slump, and compressive strength of the slurry solves a number of technical problems in shield construction. Firstly, the permeability is ≤5×10 -5Ultra-low permeability of cm / s, combined with high-density characteristics of specific gravity ≥ 1.80 g / cm³, can effectively block groundwater intrusion in water-rich soft soil layer 7, avoid dilution and loss of slurry, and at the same time, high-density slurry can form sufficient buoyancy to balance the water and soil pressure on the pipe piece 1, thereby preventing the pipe piece 1 from floating. Second, the slump of 12 cm to 16 cm and the 20h slump change of ≥5 cm index design ensures that the slurry is not easy to block the pipe during long-distance pumping, and can quickly lose fluidity after filling the annular gap, avoiding the slurry flowing and causing the pipe piece 1 to have a hollow area at the top, and solving the problem of uneven filling caused by the traditional slurry top loss and bottom accumulation. Third, the combination of water bleeding rate ≤0.3%, consolidation shrinkage rate ≤5% and expansion rate ≥0.02% ensures that the slurry almost has no water analysis during the setting process, and through micro-expansion to compensate for shrinkage, completely eliminates the micro-cracks caused by slurry shrinkage, ensures the close fit of the filling body with the pipe piece 1 and the soil layer, and significantly reduces the risk of later leakage. Fourth, the controllable range of initial setting time of 3h to 10h adapts to the tunneling rhythm of the shield, which not only reserves sufficient time for slurry pumping and filling, but also quickly forms initial strength (3-day compressive strength ≥0.10MPa), provides support for the pipe piece 1 in time, avoids displacement of the pipe piece 1 caused by slow initial setting of the slurry, and the 28-day compressive strength ≥1.0MPa meets the structural bearing requirements of long-term operation of the tunnel, ensuring the long-term stability of the filling body.

[0061] In view of the problems of traditional slurry (such as inert slurry, hardenable slurry) such as easy segregation, water bleeding, slow consolidation, poor water dispersion resistance and the like, the high-performance slurry developed by the present application has the core characteristics of "high specific gravity, low consistency, strong water dispersion resistance, fast setting and consolidation, and high consolidation strength", aiming to solve the problems of non-compact filling of shield tail void, pipe piece 1 floating, and difficult control of ground subsidence, and is the mainstream technical direction of current shield simultaneous grouting.

[0062] Flowability and workability: meet the requirements of long-distance pumping (pumping distance ≤1000m) and are not easy to block the pipe.

[0063] Water dispersion resistance: by adding a water dispersion resistant agent (such as cellulose ether), the slurry is not easy to dilute under the soaking of underground water, the water bleeding rate is ≤0.3% (the water bleeding rate of traditional inert slurry is ≥5%), and the strength of the consolidated body is ensured.

[0064] Controllable setting time: the initial setting time can be adjusted to 3-10h (for conventional soil layer 7), and for water-rich soil layer 7, it can be shortened to within 30 minutes, meeting the "timely filling of shield tail void" requirement and preventing the pipe piece 1 from floating.

[0065] High consolidation strength: 28-day compressive strength ≥1.0MPa, early compressive strength (3 days) ≥0.1MPa, effectively resisting soil pressure and groundwater penetration, and controlling ground subsidence (30-day cumulative settlement ≤20mm).

[0066] Good volume stability: limit the expansion rate ≥0.02%, compensate for slurry shrinkage, avoid solidification body cracking, and improve the adhesion with the pipe piece 1 and the soil layer.

[0067] Further, the grouting equipment of the present application adopts a large-flow and high-pressure grouting pump (such as a double-cylinder piston pump), which is matched with an automatic metering system (controlling water-cement ratio and additive content) to ensure the uniformity of the slurry.

[0068] The grouting pressure is 1.1~1.2 times the static water and soil pressure, and the grouting pressure is generally 1.5~3 bar to avoid ground uplift or pipe piece 1 deformation caused by excessive pressure; the grouting amount is calculated as 1.5~2.5 times the theoretical volume of the annular gap (1.2 m per ring shield, grouting amount 4.8~6.0 m 3 , 16 bags 4, then the average slurry amount of each bag 4 is 0.3 m 3 ~0.375 m 3 ), to ensure the gap filling density.

[0069] During grouting, a single pump with two pipelines (or more injection points if conditions permit, such as four pipelines and four injection points) is used for symmetrical grouting (two injection points), and the grouting pressure is adjusted appropriately following the site conditions to prevent pipe piece 1 from sinking or floating.

[0070] In addition, the quality of the slurry needs to be controlled: Slurry performance testing: slump, bleeding rate, and setting time of each disc of slurry are tested, and only after passing the test can the slurry be pumped.

[0071] Grouting process monitoring: real-time monitoring of grouting pressure and amount, drawing of "pressure-time-amount" curve, and judgment of gap filling condition.

[0072] Effect check: evaluate the grouting effect by ultrasonic detection (at the vault position) and ground settlement monitoring (30-day cumulative settlement ≤20 mm), and supplement grouting if necessary.

[0073] The grouting pressure during grouting is 1.1~1.2 times the static water and soil pressure, and the volume of the slurry in all bags 4 is 1.5~2.5 times the volume of the annular gap, and the above two numerical ranges (pressure is 1.1~1.2 times the static water and soil pressure, and the volume of the slurry is 1.5~2.5 times the volume of the annular gap) are the best balance point between the two conflicting goals of ensuring filling and preventing construction damage.

[0074] Grouting pressure = 1.1~1.2 times the static water and soil pressure, which is a precisely calculated active construction pressure range.

[0075] If the grouting pressure is less than or equal to 1 times the static water and soil pressure, the slurry will not be able to push away the surrounding soil and groundwater, and even cannot effectively expand the bag 4, which is 10% higher than the pressure (1.1 times) to overcome the resistance, so that the slurry can flow. The purpose of the present application is not only to fill, but also to support. This 10%~20% excess pressure (1.1~1.2 times) will exert an active extrusion and compaction on the soil layer 7 outside the bag 4, improving the density and stability of the surrounding soil layer. This active pressure can apply a uniform and controllable counter pressure to the pipe 1 through the expanded bag 4 at the moment when the pipe 1 is out of the shield tail, thereby actively fixing the pipe 1 on the designed axis, effectively inhibiting its floating or misalignment.

[0076] If the grouting pressure is too high, greater than 1.2 times the static water and soil pressure, the high grouting pressure will uncontrollably extrude the soil, causing excessive uplift of the ground surface above the tunnel, causing damage to existing roads, bridges or buildings. Controlling the upper limit of the pressure to 1.2 times is a safety valve to ensure construction safety and not to disturb the surrounding environment. The high extrusion pressure acts on the pipe 1, which is prone to cause stress concentration in the pipe 1 (especially at the joints), leading to cracking or damage of the pipe 1, which is contrary to the original intention of the present application. The upper limit of 1.2 times ensures that the applied force is a supporting force rather than a destructive force. Excessive pressure can also cause the soil layer 7 to be split, and the slurry (even in the bag 4) will form irregular invasions, destroying the soil structure; at the same time, it will also cause great damage to the bag 4 material.

[0077] Therefore, the grouting pressure of 1.1~1.2 times the static water and soil pressure is just enough to compact the soil layer and support the pipe 1, without damaging the soil layer 7 and the pipe 1.

[0078] Regarding the slurry volume = 1.5~2.5 times the annular gap volume, this excess filling volume ratio is the core quantity guarantee to ensure the final filling to be full and dense.

[0079] The annular gap is only the theoretical geometric gap between the shield shell and the outer diameter of the pipe 1. However, in actual tunneling, in order to prevent the shield machine from being stuck, the excavation diameter of the cutter head is always greater than the diameter of the shield shell, which leads to overbreak. At the same time, the soil layer 7 will relax and deform after excavation. Therefore, the real hollow area volume to be filled is much larger than the theoretical gap volume.

[0080] As mentioned earlier, the grouting pressure = 1.1~1.2 times the static water and soil pressure will compact the soil layer. During the process of soil compaction, its own volume will shrink, and this shrinking space must also be filled by the slurry to compensate for the volume consumed by soil compaction.

[0081] The slurry inside the bladder 4 will solidify and shrink, with a coefficient of 1.5 to 2.5 providing sufficient margin to compensate for any minor volume loss of the slurry during the process of changing from a fluid to a solid state.

[0082] The grout volume should be 1.5 to 2.5 times the annular gap volume, with 1.5 times the annular gap volume being the minimum requirement to ensure full grouting. Below 1.5 times, it is highly likely that the total volume resulting from over-excavation, soil compaction, and grout shrinkage may not be fully compensated, leading to a large number of voids remaining after the initial grouting in step S2, making the secondary grouting in step S3 too burdensome. Above 2.5 times, firstly, it means huge material waste and increased costs. More importantly, attempting to inject such an excessive amount of grout would inevitably require extremely high pressure (far exceeding 1.2 times), which would directly lead to surface heave and damage to segment 1.

[0083] Therefore, by synergistically limiting the two key parameters of grouting pressure = 1.1~1.2 times the static water and soil pressure and grout volume = 1.5~2.5 times the annular gap volume, the present invention ensures that the pressure is just right and the volume is injected to be absolutely full in steps S2 and S3, thereby achieving the two core objectives of safe construction and high-quality filling.

[0084] Furthermore, each of the bags 4 covers the seam of the tube segment 1, that is, the joint of any two adjacent bags 4 is staggered from the seam of the tube segment 1, so as to improve the waterproof capability of the tube segment 1.

[0085] The high-strength, high-density reinforced body formed after grouting and solidification in step S2 is precisely and preferentially placed at the joints of the tunnel structure that require the most protection. The 4-bag reinforced body forms a completely new, continuous, high-grade external waterproofing and support layer outside the segment 1. Like a robust external armor, it directly covers the outside of traditional waterproofing (such as waterstops), protecting it from direct impact from high water and soil pressure, thus constructing a double-redundant waterproofing system.

[0086] The staggered joints of any two adjacent bags 4 with the joints of segments 1 are a key structural guarantee for achieving a high level of waterproofing. This staggered or interlaced layout creates a labyrinthine or tortuous seepage prevention path in engineering: groundwater attempting to penetrate the joints of segments 1 is blocked by the solid body of the bags 4 (i.e., the belly of the bags 4). Groundwater attempting to penetrate the joints between bags 4 (theoretically secondary weak points) is also blocked by the solid body of segments 1. This design ensures that any leakage path is cut off and blocked at least twice, preventing water from finding a straight channel from the soil layer 7 to the tunnel interior. This greatly extends the water seepage path, significantly increases seepage resistance, and fundamentally eliminates the possibility of linear leakage.

[0087] This layout of the bag 4, so that a complete, solidified bag 4 entity while spanning on two adjacent segments 1. This bag 4 reinforcement as an external splint or keel, provides a continuous shear transfer and support outside the segment 1, which greatly inhibits the occurrence of misalignment between adjacent segments 1 (i.e. shear displacement).

[0088] The more detailed construction process of the present application is as follows: (1) construction segment 1, precast grouting hole 5 and preloaded bag 4 According to the design drawings, the segment 1 is provided with grouting holes 5 in the full circumferential direction, see Figure 7 , 16 grouting holes 5 are arranged in the circumferential direction, the outer pipe 51 is a steel pipe with an outer diameter of 60 mm and a thickness of 3.5 mm, the inner pipe 52 is a steel pipe with an outer diameter of 30 mm and a thickness of 3.5 mm, and the segment 1 outside each grouting hole 5 is pre-arranged with a bag 4. The bag 4 is usually made of wear-resistant and pressure-resistant material and is divided into two bag bodies to form two grouting cavities 6. The slurry is injected into the first bag body 41 close to the segment 1 through the outer pipe 51 for primary grouting and into the second bag body 42 outside through the inner pipe 52 for secondary grouting. The bag 4 should be tested for inflation before the segment 1 is assembled to check the sealing performance. The thickness after inflation should be higher than the thickness of the annular gap between the shield machine and the soil layer. The bag 4 is pre-pressed and fixed around the grouting hole 5 on the outside of the segment 1 during construction.

[0089] (2) Equipment inspection and parameter setting Check whether the grouting pump, pipeline and pressure display system are working properly to ensure that the pipeline is unobstructed and the pressure gauge is accurate. According to the geological survey report and tunnel design, the grouting pressure and grouting volume of this section of the project are calculated and set in advance to achieve precise control of the attitude of the segment 1. The grouting volume is generally 1.5-2.5 times the theoretical tail gap volume of the shield machine to compensate for the loss caused by slurry penetration and shrinkage.

[0090] (3) Configure slurry The grouting material is made by stirring lime, fly ash, bentonite, medium-fine sand, water and water reducing agent, etc. It is used for filling behind the segment wall. The solidified slurry does not liquefy under 7-degree earthquake conditions. The grouting pump needs to use an imported pump that can inject thick slurry.

[0091] (4) Jet grouting Wall hole grouting should start from the two waists of the segment 1, and the top and bottom bags 4 should be grouted simultaneously. If conditions permit, multiple points can be used simultaneously. After grouting, the grouting hole 5 should be closed. During primary grouting, multiple grouting holes 5 at different positions should be grouted simultaneously, and the slurry pressure should be gradually increased. When the bag 4 reaches the set pressure and grouting volume, grouting should be temporarily stopped to ensure that the bag 4 is fully inflated.

[0092] (5) Real-time detection of the back of the segment 1 After the first grouting, the existing shield grouting monitoring instrument is used to detect whether there is a grouting cavity area behind the shield segment 1. For the detected cavity area, the post-wall pre-embedded bag 4 is grouted in sections and blocks through the grouting hole 5 (second grouting), which forms effective support for the tunnel.

[0093] (6) Digital tracking grouting In the above-mentioned first grouting and second grouting construction, the grouting pressure, flow, expansion volume in the bag 4 and the surrounding soil deformation (such as tunnel settlement, convergence) and other data are collected in real time by pressure sensors, flow meters, displacement sensors (such as total station, level), and the sensor accuracy can reach ±1% (such as pressure sensor accuracy 0.1MPa). The adjustable bag grouting system is used, the intelligent control module is used to adjust the grouting pressure (accuracy 1%) and flow in real time, and the big data platform is used to store the whole cycle grouting data (such as grouting volume, pressure, deformation), which realizes the construction process traceability and provides data support for subsequent operation and maintenance.

[0094] (7) Hole sealing and maintenance After the digital tracking grouting is completed, the grouting hole 5 which has been grouted twice is plugged. The selection of the hole sealing material needs to meet the requirements of high strength, fast hardening, micro-expansion and waterproof, mainly including: 1) Micro-expansion cement mortar: It is a commonly used material for plugging the shield grouting hole 5, and its ratio is usually cement:sand:expanding agent=1:1.2:0.12 (such as 50kg cement+60kg sand+6kg AEA expanding agent), and the water-cement ratio is controlled at 0.5~1:1. The material has the characteristics of micro-expansion (compensating for shrinkage of mortar to avoid cracks), fast hardening (30-minute strength can reach 7MPa~7.5MPa), and is suitable for rapid sealing of the grouting hole 5.

[0095] 2) Cement-silicate double liquid slurry: For grouting holes 5 with a large amount of water leakage, cement-silicate double liquid slurry (cement to water glass volume ratio 1:0.8~1:1) is used, which has short setting time (10~30 seconds) and high early strength (1-hour strength can reach 5~10MPa), and can quickly seal the water leakage.

[0096] 3) Polyurethane hole sealing agent: For emergency water leakage (such as water gushing), polyurethane hole sealing agent (such as XZKFJ-Ⅲ mine polyurethane) is used, which has fast reaction time (solidification within a few minutes) and high expansion ratio (10~20 times), which can quickly seal the drilling hole and prevent the water leakage from expanding.

[0097] The maintenance after sealing the hole is the key to ensure the performance of the sealing material, and attention should be paid to the wet maintenance and time control, with the following specific requirements: 1) Wet maintenance Maintenance time: After the grouting hole 5 is plugged, it needs to be kept wet for ≥7 days (to avoid cracks caused by shrinkage of the material due to water loss).

[0098] Maintenance methods: Watering (water 2-3 times a day to keep the surface moist) or covering with a damp cloth (to prevent moisture from evaporating too quickly).

[0099] 2) Time control Precautions during the curing period: Do not disturb the grouting hole 5 during the curing period (such as by collision or drilling) to avoid damaging the sealing layer. Regularly check the surface of the grouting hole 5 (for example, whether there are cracks or water leakage) and deal with any abnormalities in a timely manner.

[0100] This invention uses bag-type grouting, which can control the grout and prevent it from flowing into the soil layer 7, or being diluted by groundwater, resulting in incomplete filling and easy formation of voids. The bag 4 forms a physical barrier, strictly confining the grout within the gap between the segment 1 and the soil layer. After the first grouting is completed, the presence of voids is detected first, and then a second grouting is performed. The second grouting can be carried out after the initial setting of the first grouting, ensuring full and uniform filling and significantly reducing the probability of voids.

[0101] In the existing technology, the grout filling is not dense enough, which can form water seepage channels and make the joint of the segment 1 a weak point in waterproofing. The full filling body and the bag 4 itself together form a double waterproof barrier, which effectively prevents seepage and improves waterproofing. It is especially suitable for projects with high water pressure, water-rich soil layers 7 or extremely high waterproofing requirements.

[0102] This invention addresses the issue that untimely or insufficient grouting can easily lead to the floating and misalignment of the tunnel segment 1, as well as surface settlement, especially in soft soil layers or small-radius curve sections. By employing a multi-point grouting method, deformation can be effectively controlled. At the same time, the expansion of the bladder 4 can quickly provide uniform support to the tunnel segment 1, effectively suppressing the floating and displacement of the tunnel segment 1.

[0103] This invention addresses the problem of material waste caused by grout loss and the frequent need for secondary grouting, which increases costs and construction time. Precast grout bags with four injection techniques reduce ineffective grout loss, improve material utilization, and save materials. Because of the high quality of the first filling, the workload and material consumption for subsequent secondary grouting are reduced, thus improving overall construction efficiency.

[0104] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for simultaneous grouting in a bag-type tunnel for shield tunnels, characterized in that, Includes the following steps: S1. The tunnel boring machine (TBM) assembles annular segments within the soil layer, with an annular gap between the soil layer and the segments. Each segment has multiple grouting holes on its sidewall, evenly arranged circumferentially. A sac is pre-installed on the outer wall of each segment at the position corresponding to each grouting hole. Each grouting hole includes an inner hole and an outer hole, formed by an outer tube and an inner tube located within the outer tube. The inner cavity of the inner tube forms the inner hole, and the space between the inner tube and the outer tube forms the outer hole. Each sac includes an integrally formed first sac body and a second sac body. The first sac body is located between the second sac body and the segments. The outer wall of the outer tube connects to the opening of the first sac body, and the inner tube extends into the first sac body, with its outer wall connecting to the opening of the second sac body. S2. Grout is injected into multiple first bags through the outer holes of multiple grouting holes to inflate the bags. The inflated bags compress the soil layer and the pipe segments. Then, all the grouting holes that have been grouted are sealed. In this way, grout is injected into all the first bags to fill the annular gap between the soil layer and the pipe segments, and any two adjacent inflated bags in the circumferential direction compress each other.

2. The method for simultaneous grouting of a shield tunnel using a bag-type grouting system according to claim 1, characterized in that, Also includes: S3. Use the shield grouting monitoring instrument to detect the void area outside the bag, and then inject grout into the second bag through the inner hole of the grouting hole to fill the void area.

3. The method for simultaneous grouting of a shield tunnel using a bag-type grouting system according to claim 2, characterized in that, Steps S2 and S3 also include controllable domain digital tracking grouting: the grouting pressure inside the bladder is collected by a pressure sensor, the flow rate inside the bladder is collected in real time by a flow meter, and the expansion of the bladder and the deformation data of the soil layer around the bladder are collected in real time by a displacement sensor, so that the grouting pressure and the amount of grout injected into the bladder can be adjusted in real time by an intelligent control module, thereby achieving precise filling of the voids behind the pipe segment wall and preventing attitude deviation caused by uneven grout diffusion.

4. The method for simultaneous grouting of a shield tunnel using a bag-type grouting system according to claim 3, characterized in that, By monitoring the grouting pressure and grout volume in real time, a grouting pressure-time-grout volume curve is plotted to determine the filling status of the annular void. The grouting effect is evaluated by ultrasonic detection at the top of the segment and ground settlement monitoring at the bottom of the segment, so as to supplement the grouting of the bladder.

5. The method for simultaneous grouting of a shield tunnel using a bag-type grouting system according to claim 1, characterized in that, In step S2, the grouting pressure and grout flow rate are adjusted in real time to adjust the extrusion pressure acting on the outer wall of the segment, thereby achieving precise control of the segment's posture.

6. The method for simultaneous grouting of a shield tunnel using a bag-type grouting system according to claim 1, characterized in that, In step S2, after the grout in the first bag has initially set, the second bag of the bag is then grouted based on the void detection data.

7. The method for simultaneous grouting of a shield tunnel using a bag-type grouting system according to claim 1, characterized in that, In step S2, grouting is performed simultaneously at two or four grouting holes, and these grouting holes are evenly distributed circumferentially.

8. The method for simultaneous grouting of a shield tunnel using a bag-type grouting system according to claim 1, characterized in that, In step S1, the bag skin comprises three layers of nitrile rubber and two layers of nylon fabric, which are arranged alternately. The bag skin is manufactured using a lamination process, wherein: The tensile strength of the single-layer nylon fabric is ≥272 daN / 5cm, and the tensile strength of the bag skin of the bag is ≥300 daN / 5cm; The thickness of the bag skin is 1.5mm to 2.5mm, of which the thickness of the rubber layer is 0.4mm to 1mm and the thickness of the nylon cloth layer is 0.1mm to 0.3mm; The working temperature of the bag is -30℃ to 100℃; The air permeability coefficient of the nitrile rubber layer is ≤0.01cm. 3 / (cm·s·cmHg).

9. The method for simultaneous grouting of a shield tunnel using a bag-type grouting system according to claim 1, characterized in that, In step S2, the slurry comprises lime, fly ash, medium and fine sand, bentonite, water, and a water-reducing agent, and: The lime is hydrated lime, and the calcium hydroxide content of the lime is ≥85%, with a residue of ≤0.5% on a 320-mesh sieve; The fly ash fineness grade is Class II, with a residue of ≤20% on a 0.045mm square-hole sieve; The medium and fine sand used is river sand with a fineness modulus of 1.8 to 2.2 and a mud content of ≤3%. The bentonite has a 200-mesh sieve residue of ≤5% and an expansion rate of 18mL / g to 30mL / g. The water-reducing agent has a density of 1.06 ± 0.01 g / cm³ at 20°C. 3 The water reduction rate is 20% to 30%; The performance indicators of the slurry are as follows: permeability ≤ 5×10 -5 cm / s, specific gravity ≥1.80g / cm 3 The slump is 12cm~16cm, the slump change is ≥5cm after 20h, the compressive strength after 3 days of solidification is ≥0.10MPa, the compressive strength after 7 days of solidification is ≥0.15MPa, the compressive strength after 28 days of solidification is ≥1.0MPa, the consolidation shrinkage rate is ≤5%, the expansion rate is ≥0.02%, the bleeding rate is ≤0.3%, and the initial setting time is 3h~10h.

10. The method for simultaneous grouting of a shield tunnel using a bag-type grouting system according to claim 1, characterized in that, In step S2, the grouting pressure during grouting is 1.1 to 1.2 times the static water and soil pressure, and the volume of grout in all the bags is 1.5 to 2.5 times the volume of the annular gap.

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