Shield efficient crossing reservoir stability analysis and safety control construction method

Abstract

The invention discloses a shield efficient crossing reservoir stability analysis and safety control construction method. The method comprises the following steps of S1, preparation before construction and geological investigation; s2, riprap silt squeezing and cofferdam construction; s3, backfilling and compacting the back pressure covering soil layer by layer; s4, performing left line shield crossing parameter control and informatization management; s5, pre-reinforcing the left line tunnel before the right line passes through the tunnel for the second time; s6, right line shield crossing dynamic control and emergency plugging are carried out; and S7, post-construction stability monitoring and evaluation are conducted, specifically, a silt layer is replaced and compacted through stone throwing and filling according to the principle of stone throwing and silt squeezing, meanwhile, the thrown and filled stone is rolled through a vibration rolling machine, then the stability and bearing capacity of a foundation are enhanced through back-pressure soil covering, the foundation is fully combined with silt, and a stable stone cushion layer is formed. The technology can effectively reduce the settling volume of the original overburden layer, ensures the stability and safety of the tunnel, avoids pollution and damage to the surrounding environment of the water area, and has better adaptability in the water area environment.

Description

Technical Field

[0001] The present invention relates to the field of television technology, and more particularly to a shield tunneling high-efficiency reservoir crossing stability analysis and safety control construction method. Background Art

[0002] With the gradual expansion of domestic underground projects, many shield tunnels are restricted by the use of routes and need to pass through water areas (rivers, lakes, reservoirs), resulting in a shallow overburden layer at the location of the tunnel. During the tunneling process of the shield machine under the conditions of high water pressure, strong permeability, and shallow overburden (the thickness of the overburden is less than one times the diameter of the shield machine), it is very easy to experience face instability, stratum subsidence, water seepage and slurry, and local disturbance liquefaction. In particular, in the water area, the double-hole interval tunnel requires a secondary small-clearance shield side-through of the existing formed tunnel, which is extremely difficult and has great engineering risks in terms of stability and safety control construction technology. The construction site often uses water-stop curtains, back-pressure backfill, grouting reinforcement and other methods for reinforcement. However, from the perspective of reinforcement methods and foundation construction of commonly used underpass solutions, the following problems are found to exist: (1) Uncertainty of reinforcement effect. The effect of water-stop curtain is often affected by many factors such as geological conditions, water pressure, curtain material properties, etc. It is difficult to ensure complete water-stopping. The diffusion range and curing strength of grouting reinforcement are also difficult to control accurately, resulting in unstable reinforcement effect.

[0003] (2) Impact on the surrounding environment: Construction methods such as water-stop curtains and grouting reinforcement may cause changes in groundwater levels and pollute the ecological environment of surrounding waters.

[0004] (3) Limitations of scheme adaptability: Different geological conditions and hydrological environments require different reinforcement schemes, but existing reinforcement methods are often difficult to adapt to all situations.

[0005] Customized reinforcement solutions may be required for specific engineering conditions, which increases the complexity of design and construction.

[0006] (4) Long-term stability. The long-term stability of the reinforced structure is the key to successful construction. However, existing reinforcement methods often cannot guarantee long-term stability without deformation or failure. Regular inspection and maintenance of the reinforced structure are required, which increases the cost and difficulty of subsequent operations.

[0007] Therefore, in response to the above problems, a stability analysis and safety control construction method for shield tunneling efficiently crossing a reservoir is proposed. Summary of the Invention

[0008] In order to overcome the above-mentioned defects of the prior art, the present invention provides a shield tunneling efficient crossing reservoir stability analysis and safety control construction method to solve the problems raised in the above-mentioned background technology.

[0009] To achieve the above-mentioned object, the present invention provides the following technical solution: a shield tunneling high-efficiency reservoir crossing stability analysis and safety control construction method, comprising the following steps: S1. Pre-construction preparation and geological survey: Use HSP technology to survey the geology in front of the tunnel face 20m before the shield tunnel crosses the water, identify risk points, and optimize the design of the riprap and silt removal range and backpressure cover thickness based on the geological conditions; S2. Rock dumping and cofferdam construction: Rock dumping is carried out along the centerline of the cofferdam from smaller to larger mileages, expanding in layers to the designed width. Rock dumping is carried out 30 cm above the water surface and then repeatedly compacted using the excavator's own weight. When the amount of silt subsided approaches zero, rocks are added to the designed elevation. Polypropylene woven cloth is laid on the cofferdam slope. S3. Backfill and compaction of back-pressure soil in layers: After draining, remove the silt from the reservoir bottom to the hard soil layer, dry the silt and backfill it to the non-load-bearing area. Use segmented and layered stepped paving and compaction to backfill in layers. S4, Left-line shield tunneling parameter control and information management: A test section is set up 30m before the underpass to collect thrust, torque, and excavation data in real time to optimize tunneling parameters, establish a historical database, automatically warn of deviations from preset thresholds, and synchronize grouting and water stop ring installation; S5. Pre-reinforcement of the left-line tunnel before the second crossing of the right line: radial grouting of the left-line tunnel segments. Daily ground radar scanning during the right-line crossing to identify soil disturbances and seepage channels. S6, dynamic control and emergency blocking of right-line shield tunneling: tunneling in earth pressure balance mode, with the speed reduced to 80% of the left-line speed, continuous injection of polymer sealing grease, and injection of bentonite slurry into the soil bin to form a low-permeability mud film; S7. Post-construction stability monitoring and evaluation: Establish a multi-dimensional monitoring system, and continuously monitor within a range of 1000m for 60 days after the crossing is completed. After the data stabilizes, it will be handed over to the operating unit.

[0010] Preferably, in step S1, the logical steps of the HSP technology are: ; in, represents the frequency domain response; It represents the quantitative difference in wave impedance at the interface between two media, which determines the proportion of reflected energy; It represents the two-way travel time of the reflected wave described by the pulse function, which is used to locate the depth d of the geological interface; t represents the total time from the excitation to the reception of the reflected wave; v1 represents the P-wave velocity of the first medium; v2 represents the P-wave velocity of the second medium; Indicates the distance between the excitation point and the receiving point; represents the apparent velocity; It means converting the time domain signal into the frequency domain; finally, the inversion imaging of the stratigraphic structure is achieved through the joint analysis of time and frequency.

[0011] Preferably, in step S2, the riprap and silt removal is carried out by using an excavator in conjunction with manual labor to simultaneously construct two cofferdams, with the riprap sequence being thrown forward along the center line of the cofferdam and then expanded laterally to both ends in sequence, with both sides of the cofferdam being sloped at a ratio of 1:1.5.

[0012] Preferably, in step S3, the plane range of the segmented and layered stepped paving and compacting construction is 10m outward on both sides of the tunnel cross section, and both sides of the longitudinal section are connected to the road through a gentle fill slope. The backfill corners and areas that cannot be compacted mechanically are compacted with a flat plate compactor, and other areas are mechanically leveled with a vibratory roller.

[0013] Preferably, in step S3, the plane construction scope of the segmented and layered stepped paving and compacting construction is limited to 10m on both sides of the tunnel cross section, and the longitudinal section is smoothly connected to the existing road by slowing down the fill slope. The corners and areas that cannot be compacted by machinery are compacted by flat plate compactors, and other areas are compacted by vibratory rollers in layers. The filling sequence is longitudinal paving. During the segmented and layered stepped paving and compacting construction, the soil is transported to the bottom of the reservoir bank by dump trucks, and paved from the middle to both sides by excavators. The virtual paving thickness is completed by longitudinal rolling first and then transverse rolling. Each layer of backfill is compacted continuously on the same day, and drainage measures are set.

[0014] Preferably, in step S4, an information platform is used to collect the thrust, torque, earth pressure, grouting volume and synchronous posture data of the shield cutter head in real time, and the preset thresholds are total thrust ≤ 3700t, torque ≤ 2600kN.m, and excavation coefficient ≤ 1.3. The real-time data is dynamically compared with the preset thresholds, and a three-level early warning mechanism is established for automatic early warning. The three-level early warning mechanism is: A deviation of 5%-10% from the preset threshold triggers a yellow warning; A deviation of 10%-15% from the preset threshold triggers an orange warning; A deviation of >15% from the preset threshold triggers a red shutdown command.

[0015] Preferably, in step S4, the synchronous grouting is controlled to add 4% concentration of water glass as a coagulant into the grouting material, and the mixing ratio of the grouting material and the water glass is 1:1. A grouting operation is performed after the pipe segment is removed from the shield tail and after the water stop ring is set. The water stop ring is set for every 5 rings of tunnel excavation.

[0016] Preferably, in step S5, grouting is performed on the most unfavorable points of the 20-ring formed tunnel segments before and after the left-line water area, and the slurry type is cement-water glass slurry. For the right-line crossing area, high-frequency electromagnetic waves are emitted underground by radar, and the reflected electromagnetic waves are accurately recorded by the radar to form a cross-sectional scanning image to judge the actual situation of the underground target.

[0017] Preferably, in step S6, shield tail sealing grease is continuously and uninterruptedly injected during the crossing, and the shield tail sealing grease is continuously pumped until there is no leakage before continuing the excavation. The leakage phenomenon is eliminated by a dedicated person through a sponge strip equipped on site that is embedded in the gap between the shield tail shell and the pipe segment along the entire circumference.

[0018] Preferably, in step S7, the multidimensional monitoring system includes geological condition monitoring dimension, construction parameter monitoring dimension, structural safety monitoring dimension, surface environment monitoring dimension and long-term stability monitoring dimension, and the risk level is divided according to the monitoring results of the multidimensional monitoring system, so as to reinforce the tunnel accordingly.

[0019] Technical effects and advantages of the present invention: 1. Compared with the existing technology, this shield tunneling high-efficiency reservoir crossing stability analysis and safety control construction method replaces and compacts the silt layer by dumping stones, and uses a vibrating roller to compact the dumped stones. Then, back-pressure backfilling is used to enhance the stability and bearing capacity of the foundation, so that it is fully combined with the silt to form a stable stone cushion layer. This technology can effectively reduce the settlement of the original backfill layer, ensure the stability and safety of the tunnel, and avoid pollution and damage to the surrounding environment of the water area. It has better adaptability in the water environment, is simple to construct and easy to operate, and greatly shortens the construction period and reduces the cost of multi-process management.

[0020] 2. Compared with the existing technology, this shield tunneling efficient crossing reservoir stability analysis and safety control construction method combines the safety control construction measures and stability analysis of the left-line shield tunneling through shallow-covered complex geological waters, and develops the right-line secondary small clear distance crossing water safety control construction technology and stability analysis technology. According to the geological conditions and water characteristics, the shield machine's excavation speed, earth pressure balance, incision water pressure and other key parameters are strictly controlled. During the excavation process, synchronous grouting is strengthened to fill the stratum voids and improve the stratum bearing capacity. After the construction is completed, long-term settlement monitoring is carried out to achieve the construction quality required by the design and specifications and meet the final requirements of post-construction settlement. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a flow chart of the construction method of the present invention.

[0022] Figure 2 Schematic diagram of the mechanical rolling sequence in step S3 of the present invention. DETAILED DESCRIPTION

[0023] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0024] Example 1 As attached Figures 1 to 2 The stability analysis and safety control construction method of a shield tunneling machine efficiently crossing a reservoir shown includes the following steps: S1. Pre-construction preparation and geological survey: Use HSP technology to survey the geology in front of the tunnel face 20m before the shield tunnel crosses the water, identify risk points, and optimize the design of the riprap and silt removal range and backpressure cover thickness based on geological conditions; S2. Rock dumping and cofferdam construction: Rock dumping is carried out along the centerline of the cofferdam from smaller to larger mileages, expanding in layers to the designed width. Rock dumping is carried out 30 cm above the water surface and then repeatedly compacted using the excavator's own weight. When the amount of silt subsided approaches zero, rocks are added to the designed elevation. Polypropylene woven cloth is laid on the cofferdam slope. S3. Backfill and compaction of back-pressure soil in layers: After draining, remove the silt from the reservoir bottom to the hard soil layer, dry the silt and backfill it to the non-load-bearing area. Use segmented and layered stepped paving and compaction to backfill in layers. S4, Left-line shield tunneling parameter control and information management: A test section is set up 30m before the underpass to collect thrust, torque, and excavation data in real time to optimize tunneling parameters, establish a historical database, automatically warn of deviations from preset thresholds, and synchronize grouting and water stop ring installation; S5. Pre-reinforcement of the left-line tunnel before the second crossing of the right line: radial grouting of the left-line tunnel segments. Daily ground radar scanning during the right-line crossing to identify soil disturbances and seepage channels. S6, dynamic control and emergency blocking of right-line shield tunneling: tunneling in earth pressure balance mode, with the speed reduced to 80% of the left-line speed, continuous injection of polymer sealing grease, and injection of bentonite slurry into the soil bin to form a low-permeability mud film; S7. Post-construction stability monitoring and evaluation: Establish a multi-dimensional monitoring system, and continuously monitor within a range of 1000m for 60 days after the crossing is completed. After the data stabilizes, it will be handed over to the operating unit.

[0025] Specifically, before construction, within 20m before the shield tunnel crosses the water, HSP technology is used to emit elastic waves in front of the tunnel face, analyze the imaging data of the reflected energy group, and detect risk points such as caves, broken strata, and water-rich structural belts within a range of 100m. The range of riprap and silt extrusion and the thickness of the back pressure cover are adjusted according to the detection results. If a weak interlayer is found, the riprap and silt extrusion cofferdam is locally intensified to 1.5 times the design width, and the back pressure cover thickness is increased to 15m. At the same time, the earthwork transportation route is clarified, the storage of riprap and cover materials and the commissioning of equipment are completed, and the construction personnel are given a visual explanation of the 3D geological model; S2. Use the advance method for construction, advancing from smaller to larger mileages along the centerline of the cofferdam, and expanding horizontally to the designed width, which is 4m at the top. After the riprap is 30cm above the water surface, use a 20t excavator to repeatedly roll it along a "Z" path 6-8 times until the riprap layer sinks ≤5mm / 12h. After the cofferdam slope is sloped at a ratio of 1:1.5, 240g / m² polypropylene woven cloth is laid with an overlap length of ≥1m. U-shaped nails are used to secure it in a 2m×2m plum blossom pattern to prevent water infiltration and slope scouring. The riprap particle size is controlled at 30-50cm, and the mud content is ≤3%. The cofferdam top elevation error is ±50mm, and the axis deviation is ≤100mm. S3. After draining the accumulated water, remove the silt from the reservoir bottom to the hard soil layer to a depth of ≥1.2m. After airing, backfill the silt to a non-load-bearing area 15m outside the tunnel axis using a step-by-step paving method, with each layer ≤300mm thick. Use an 18t vibratory roller to compact the mechanically compacted area 3-4 times in a "vertical then horizontal" pattern. Use a flat plate compactor to compact the corners 6-8 times in layers. After each layer is compacted, use the ring knife method to test for a compaction degree of ≥90%. After completion, conduct a static load test to ensure the foundation bearing capacity characteristic value is ≥150kPa. S4. A test section was set up 30m before the crossing, and real-time data such as thrust of 2500-3700t, torque of 1700-2600kN·m, and penetration of 30-40mm / r were collected. A parameter-settlement correlation model was established using a machine learning algorithm. The "shield brain" system was used to monitor parameters such as soil bin pressure of 1.0-1.1bar and grouting volume of 1.28-1.3 times the theoretical value in real time. If the soil pressure fluctuation was greater than 0.05bar / min, the warning threshold was automatically triggered. A cement-water glass dual liquid slurry with a volume ratio of 1:1 was used, and the initial setting time was controlled at 45-60s. Water stop rings were installed every five rings, and the grouting pressure was 0.3-0.5MPa. S5. Drill 42-diameter grouting holes at the most unfavorable locations at points 2-5 and 7-10 of the left-line tunnel, with a depth of 1.2 m. Inject cement-water glass grout with a water-cement ratio of 1:1, a Baume degree of 38°Bé, and a grouting volume of 0.3 m³ / ring. Use a 400 MHz antenna for ground scanning, with 0.5 m spacing between horizontal lines and profiles every 10 m vertically. Identify soil disturbance areas with a dielectric constant greater than 15 and seepage channels. Sleeve valve pipe grouting will be implemented in the identified seepage channels at a grouting pressure of 0.5-0.8 MPa and a diffusion radius of 1.5 m. In S6, earth pressure balance mode, the speed is reduced to 80% of the left line, the cutterhead speed is 1.0-1.2r / min, the soil bin pressure is increased by 10%, polyurethane sealing grease is continuously injected, and bentonite slurry is injected into the soil bin to form a low-permeability mud film with a thickness of ≥20mm. In case of slurry leakage, a 300mm×300mm sponge strip with an overlap length of 100mm is immediately embedded, and the shield tail grease pumping pressure is increased to 4MPa; S7. Set up automated monitoring points to collect data such as surface settlement, segment convergence, and pore water pressure in real time. After the crossing is completed, continuous monitoring will be carried out within a range of 1000m for 60 days. The data stability standards are: daily surface settlement ≤0.2mm / d, segment convergence rate ≤0.05mm / d, and seepage ≤0.1L / m²·d. The monitoring data will be processed by cubic spline interpolation to generate displacement contour maps. When the coefficient of variation is less than 5%, it will be handed over to the operating unit, and a full life cycle digital twin model will be established.

[0026] This method uses the "rock dumping and silt removal-counter pressure covering" composite foundation improvement technology to increase the underwater cover thickness to three times the shield diameter. Combined with HSP advanced detection and information-based dynamic control, the cumulative settlement of the double-line crossing is controlled within -18.1mm. Compared with traditional construction methods, the stability is improved by more than 40% and the construction period is shortened by 25%.

[0027] Example 2 Based on Example 1, the solution in Example 1 is further detailed in combination with the following specific working methods. Figures 1 to 2 As shown, see the following description for details: As a preferred embodiment, in step S1, the logical steps of the HSP technology are: ; in, represents the frequency domain response; It represents the quantitative difference in wave impedance at the interface between two media, which determines the proportion of reflected energy; It represents the two-way travel time of the reflected wave described by the pulse function, which is used to locate the depth d of the geological interface; t represents the total time from the excitation to the reception of the reflected wave; v1 represents the P-wave velocity of the first medium; v2 represents the P-wave velocity of the second medium; Indicates the distance between the excitation point and the receiving point; represents the apparent velocity; It means converting the time domain signal into the frequency domain; finally, the inversion imaging of the stratigraphic structure is achieved through the joint analysis of time and frequency.

[0028] Specifically, HSP advanced geological exploration technology was introduced to clarify the geology ahead of the tunnel face. This technology was used 20 meters before the shield tunnel crossed the water. This technology uses the vibration signals generated by the shield cutterhead shearing the rock as elastic waves. Based on the image of the elastic wave reflection energy cluster and analysis of survey data, it can be determined whether there are unfavorable geological conditions such as caves, fractured strata, weak interlayers, densely jointed zones, and water-rich structural zones within 100 meters ahead. Corresponding measures can be taken in advance to guide the shield tunneling. By stimulating sound waves and collecting reflected signals, the mapping relationship between geological interface spatial parameters and wavefield parameters is established by combining wave impedance differences, time-frequency characteristics, and wavefield propagation patterns. In practical applications, time-frequency analysis techniques such as S-transform are used to perform signal denoising. The detection range can reach 70-100 meters, with a resolution of 0.5 meters.

[0029] As a preferred embodiment, in step S2, the riprap and silt removal are carried out by using an excavator and manual cooperation to construct two cofferdams at the same time. The riprap is thrown forward along the center line of the cofferdam and then expanded horizontally to both ends in sequence. The slope of both sides of the cofferdam is 1:1.5.

[0030] Specifically, riprap and silt removal were carried out using an excavator in conjunction with manual labor, using the advance method. Construction on both cofferdams was carried out simultaneously. The riprap was carried out from one end of the reservoir to the other, along the centerline of the cofferdam, and then expanded horizontally to both ends. Slope repairs were performed during the riprap process, and the work progressed sequentially. The top elevation of the riprap cofferdam is 43m, and the slope of both sides is 1:1.5 to ensure the self-stability of the cofferdam. When the riprap is about 30cm out of the water, the excavator's own weight is used to move back and forth and roll the riprap to make the riprap sink and stabilize. When the riprap tends to sink, it is repeatedly added with stones and rolled until there is no sinking phenomenon and the cofferdam reaches the design elevation. The cycle is carried out in sequence. After the riprap cofferdam is completed, its cofferdam slope is covered with waterproof geotextile and compacted and fixed, which mainly prevents slope scouring and isolates water bodies. The waterproof geotextile is made of 240g / m2 polypropylene woven cloth. After the riprap cofferdam is filled, multiple high-power pumps are used to pump the water in the cofferdam to the outside of the right cofferdam to form land operations.

[0031] As a preferred embodiment, in step S3, the plane range of the segmented and layered stepped paving and compacting construction is 10m outward on both sides of the tunnel cross section, and both sides of the longitudinal section are connected to the road through a gentle fill slope. The backfill corners and areas that cannot be compacted mechanically are compacted with a flat plate compactor, and other areas are mechanically leveled with a vibratory roller.

[0032] Specifically, silt must be removed from the reservoir bottom during backfilling, and silt must be gradually removed as the backfill is filled to ensure backfill density, prevent the formation of an elastic foundation, and improve the backfill's bearing capacity. The desilted soil is aired in a nearby open space before being backfilled below the surface. Backfill construction utilizes a segmented, layered, stepped paving and compaction process. The horizontal range extends 10m outward on both sides of the tunnel's cross section, and the vertical section is sloped to allow for smooth connection with existing roads. Backfill corners and areas where mechanical compaction is impractical are compacted manually or with a flatbed compactor. Layered fill thickness should not exceed 200mm, and the number of compaction passes should be 6-8. Mechanical leveling rollers (vibratory rollers) are used in other areas. Layered fill thickness should not exceed 300mm, and the number of compaction passes should be 3-4. The fill density should not be less than the design requirement, with a density of ≥90%.

[0033] As a preferred embodiment, in step S3, the plane construction scope of the segmented and layered stepped paving and compacting construction is limited to 10m on both sides of the tunnel cross section, and the longitudinal section is smoothly connected to the existing road by slowing down the fill slope. The corners and areas that cannot be compacted by machinery are compacted by flat plate compactors, and other areas are compacted by vibratory rollers in layers. The filling sequence is longitudinal paving. During the segmented and layered stepped paving and compacting construction, the soil is transported to the bottom of the reservoir bank by dump trucks, and paved from the middle to both sides by excavators. The virtual paving thickness is completed by longitudinal rolling first and then transverse rolling. Each layer of backfill is compacted continuously on the same day, and drainage measures are set.

[0034] Specifically, the backfill sequence is longitudinal, with the upper and lower layers backfilling in areas with height differences, and the overlap length of each backfill should be no less than 500mm. After the backfill is completed, it should be leveled with a line. Any areas above the design elevation should be promptly leveled, and areas below the design elevation should be loosened with an excavator and then filled and compacted.

[0035] Each layer of backfill should be completed continuously and as quickly as possible, with the soil compacted on the same day. During construction, prevent water from outside the dam from flowing into the backfill surface, and work should be done on rain-free days whenever possible. If the backfill soil is flooded, remove the sludge before proceeding to the next step.

[0036] During backfill construction, dump trucks transport the soil to the bottom of the reservoir bank, and excavators or bulldozers shovel the soil filling into place and roughly level it. The paving route is from the smaller mileage end to the larger mileage end, and paving from the middle to both sides, paying attention to the thickness of the virtual paving.

[0037] When compacting in layers, the roller should apply a light stroke first, then a heavy stroke, slowly then quickly, and repeatedly, from the edges to the center. During compaction, the wheel tracks should overlap by 1 / 3 of the wheel width to ensure uniform compaction without any gaps. Corners that cannot be compacted should be compacted with manual pushers or small equipment.

[0038] The mechanical rolling process adopts the method of rolling longitudinally first and then horizontally, that is, rolling according to the left diagram and then the right diagram. The driving speed should be controlled during the rolling process and generally should not exceed 2km / h.

[0039] During manual tamping, the overlap between the tampers must not be less than one-third of the tamping bottom width. After the backfilling is completed, the side slope is repaired with a slope of 1:1.5, and then prefabricated hexagonal frames + grass planting are used for protection.

[0040] As a preferred embodiment, in step S4, an information platform is used to collect the thrust, torque, earth pressure, grouting volume and synchronous posture data of the shield cutter head in real time. The preset thresholds are total thrust ≤ 3700t, torque ≤ 2600kN.m, and excavation coefficient ≤ 1.3. The real-time data is dynamically compared with the preset thresholds, and a three-level early warning mechanism is established for automatic early warning. The three-level early warning mechanism is as follows: A deviation of 5% to 10% from the preset threshold triggers a yellow warning; A deviation of 10% to 15% from the preset threshold triggers an orange warning; A deviation of >15% from the preset threshold triggers a red shutdown command.

[0041] Specifically, a yellow warning is triggered when the parameter is close to exceeding the limit, and the warning is automatically pushed to the HMI interface of the operation room, starting the parameter optimization suggestion module; an orange warning is triggered when the parameter is significantly abnormal, and the grouting system compensation mode is forcibly activated, and a text message is sent to the technical person in charge; a parameter >15% is a major safety risk, triggering a red warning, automatically shutting off the propulsion hydraulic system, triggering a shutdown command, and activating the emergency plan, including: Yellow warning stage: The platform automatically retrieves historical data of similar operating conditions and recommends torque / thrust optimization solutions. The operator must complete parameter review and feedback on the results within 10 minutes. Orange warning stage: The dual-liquid grouting system is forced to start, the synchronous grouting pressure is increased to 0.5MPa, and the geological radar starts to intensify scanning, increasing from once a day to once an hour; Red warning stage: Automatically activate the shield tail emergency sealing system to inject polymer sealant + embed sponge strips to start the adjacent molding tunnel automatic monitoring convergence meter + fiber optic sensing, and transmit deformation data in real time.

[0042] As a preferred embodiment, in step S4, the synchronous grouting control adds 4% concentration of water glass as a coagulant to the grouting material, and the mixing ratio of the grouting material and the water glass is: 1:1. A grouting operation is performed after the pipe segment is removed from the shield tail and after the water stop ring is set. A water stop ring is set for every 5 rings of tunnel excavation.

[0043] Grouting beneath the water is a critical step. During this phase, a coagulant (water glass) is added to the grouting material to significantly shorten the slurry's setting time and rapidly increase its strength, effectively preventing the formed tunnel segments from floating upward due to buoyancy. Timely secondary grouting at each ring further consolidates the soil surrounding the tunnel, filling voids created by excavation, reducing ground disturbance, and improving the tunnel's overall stability.

[0044] To effectively prevent groundwater from flowing through the shield into the cutterhead and soil bunker, a waterstop ring was installed every five tunnel rings. The waterstop rings utilize a dual-liquid slurry material, a mixture of water glass and cement slurry, which is characterized by rapid setting and excellent water-stopping properties. The waterstop rings effectively control groundwater during tunnel excavation, ensuring the stability and safety of the tunnel during long-term operation. They also effectively prevent the impact of developing groundwater systems on tunnel excavation and operation. Using safety control measures implemented during the left-line shield tunneling through a shallow, complex geological area, the backfill surrounding the area and the tunnel quality were both controlled. Data analysis shows that daily surface settlement has been within ±2 mm / day, with a maximum cumulative surface settlement of -18.1 mm. The daily variation in tunnel clearance convergence has been within ±0.5 mm / day, with a maximum cumulative variation of -1.8 mm. Following enhanced grouting and the subsequent injection of waterstop rings, the uplift of the segments in the water area has been largely controlled to between 10 and 15 mm.

[0045] As a preferred embodiment, in step S5, grouting is performed on the most unfavorable points of the 20-ring formed tunnel segments before and after the left-line water area, using cement-water glass slurry. For the right-line crossing area, high-frequency electromagnetic waves are emitted underground by radar, and the reflected electromagnetic waves are accurately recorded by the radar to form a cross-sectional scan image to determine the actual situation of the underground target.

[0046] Specifically, the net spacing between the left and right tunnels in the section is 6.8m, and the time interval before and after the underpass is 60 days. The stability analysis of the left-line tunnel during the second small net spacing of the right line is the key research direction of this construction method. Based on construction experience and the stress calculation of the most unfavorable point of the lateral crossing of the existing tunnel, the second crossing of the right line through the water area mainly causes the left-line tunnel to bear the lateral deformation caused by the vertical load and horizontal earth pressure. The most unfavorable points are 2 to 5 and 7 to 10. Before the right line crosses the water area, the 20 rings of the left-line tunnel segments are grouting at 2 to 5 and 7 to 10. The grouting type is cement-water glass grout. The volume ratio of cement slurry to water glass is 1:1, the Baume degree of water glass is 38°Bé, the water-cement ratio of cement slurry is 1:1 by mass, and the grouting pressure is: initial pressure 0.2-0.3MPa, steady pressure: 0.3-0.5MPa. Geological radar is a nondestructive exploration method that uses broadband, high-frequency electromagnetic signals to survey the distribution of media. It obtains cross-sectional scanning images by continuously dragging an antenna. Radar transmits high-frequency electromagnetic waves into the ground. As the electromagnetic wave signals propagate through an object, they are reflected, transmitted, and refracted when they encounter interfaces between different media. The greater the difference in dielectric constant between the media, the greater the energy of the reflected electromagnetic wave. The reflected electromagnetic wave is received by a receiving antenna that moves synchronously with the transmitting antenna. The radar host accurately records the motion characteristics of the reflected electromagnetic wave. Through data processing, a cross-sectional scanning image is generated. This image is then interpreted to determine the actual location of the underground target. The geological radar antenna transmits electromagnetic waves into the object, analyzing the location and depth of the target within the medium. Ground radar surveys were conducted daily during the right line's underpass. After the right line completed the reservoir excavation, radar scanning was used to verify the grouting status of the ground and the walls of the completed tunnel segments on both sides. Verification confirmed no obvious cavities in the ground test area, and the tunnel was fully grouted.

[0047] As a preferred embodiment, in step S6, shield tail sealing grease is continuously and uninterruptedly injected during the crossing, and the shield tail sealing grease is continuously pumped until there is no leakage before continuing the excavation. The leakage phenomenon is corrected by a dedicated person through a sponge strip equipped on site that is embedded in the gap between the shield tail shell and the pipe segment along the entire circumference.

[0048] Specifically, shield tail sealing grease is a key factor in preventing slurry leakage. Therefore, when passing through this area, high-quality sealing grease should be selected, and the injection time and pressure of the grease should be controlled. During the crossing, the shield tail sealing grease should be continuously and uninterruptedly injected. If slurry leakage occurs, excavation should be suspended immediately, and the shield tail sealing grease should be continuously pumped until the slurry leakage stops before excavation can be continued. After the slurry leakage occurs, while the shield tail sealing grease is continuously pumped to seal the shield tail, a dedicated person will immediately implement emergency plugging with the sponge strips provided on site. That is, the sponge strips are embedded in the gap between the shield tail shell and the pipe segment along the entire circumference to prevent further leakage and ground subsidence. The sponge strips have an overlap length of 100cm and a size of 300mm×300mm. In previous construction, the sponge strips have a good sealing effect on slurry leakage from the shield tail.

[0049] Sponge strips are attached to the outside of the longitudinal seams of the segments, and are pressed between the outside of the segments and the shield shell to form a closed ring. Bentonite is injected into the soil bin to improve the fluidity and water-stopping properties of the sandy soil. Grease is injected regularly, quantitatively and evenly at the shield tail to improve the sealing performance of the shield tail, prevent groundwater and sand from seeping into the tunnel from the shield tail, maintain soil pressure to prevent gushing, and prevent the soil in front from collapsing.

[0050] As a preferred embodiment, in step S7, the multidimensional monitoring system includes geological condition monitoring dimension, construction parameter monitoring dimension, structural safety monitoring dimension, surface environment monitoring dimension and long-term stability monitoring dimension. The risk level is divided according to the monitoring results of the multidimensional monitoring system, so that the tunnel is reinforced accordingly.

[0051] Specifically, under the technical measures for safety control of the right-line shield tunneling through shallow overburden and complex geological waters, the quality of the backfill soil and tunnel around the water area can be controlled. According to data summary and analysis, the daily surface settlement is between ±1mm / d, and the maximum cumulative surface settlement is -18.1mm; the daily change of the clearance convergence in the tunnel is between ±0.5mm / d, and the maximum cumulative change is -1.8mm; after taking measures such as strengthening grouting and injecting water-stop rings at the rear, the floating amount of the pipe segments in the water area is basically controlled between 10 and 15mm. The project surveyed, planned and tracked the environment around the reservoir in advance, and carried out management and control in many aspects, including reinforcement before crossing, formulating appropriate construction parameters during crossing, control measures taken on the ground and in the tunnel, and ensuring the quality of the formed tunnel after crossing. Finally, it took 94 days for the two tunnels to successfully cross the Tangwaikou Reservoir. The geological condition monitoring dimension utilizes the vibration signals generated by the shield cutterhead cutting rock and soil to analyze geological anomalies within a range of 100 meters ahead. High-frequency electromagnetic wave reflection signals are used to detect in real time the density, cavities, and water seepage of the soil surrounding the left-line formed tunnel during the second crossing of the right line. Ground scans are conducted once a day to ensure that ground disturbances are controllable. The construction parameter monitoring dimension collects key parameters such as shield thrust, torque, cutterhead speed, penetration, and soil bin pressure in real time, establishes a historical database, and optimizes parameter combinations through algorithms to improve tunneling efficiency. A test section is set up 30m before passing through the reservoir, and the optimal tunneling speed, grouting volume, and other parameters are inferred from surface settlement data. In terms of structural safety monitoring, synchronous grouting technology with water glass has been added to shorten the slurry setting time and inhibit the floating of the segments. Secondary grouting is performed in each ring to fill the gaps and reduce ground disturbance. A double-liquid slurry water stop ring is installed every five rings to block groundwater seepage. In the event of slurry leakage, a 300mm×300mm sponge strip is embedded for emergency plugging to prevent soil erosion. The daily change is controlled to ±0.5mm / day, with a maximum cumulative change of -1.8mm, ensuring that the tunnel structure does not deform. Surface environmental monitoring uses total stations and levels to monitor daily surface subsidence in real time. The maximum cumulative subsidence is -18.1mm. Rock dumping and silt squeezing counter-pressure backfilling technology is used to reduce compression and deformation of the cover layer. Polypropylene woven fabric is laid on the outside of the rock dumping and silt squeezing cofferdam to isolate the construction area from the reservoir water and prevent mud contamination. In the long-term stability monitoring dimension, the dual lines are continuously monitored after being 1000m out of the reservoir. The data change rate is stable. The back pressure covering soil also serves as an anti-floating plate. The long-term anti-floating effect is verified by the floating volume data of the pipe segments.

[0052] The working process of the present invention is as follows: Before construction, within 20m before the shield tunnel crosses the water, elastic waves are emitted in front of the tunnel face using HSP technology. The reflected energy group imaging data is analyzed to detect risk points such as caves, broken strata, and water-rich structural zones within a 100m range. The range of riprap and silt removal and the thickness of the backpressure cover are adjusted based on the detection results. If a weak interlayer is found, the riprap and silt removal cofferdam is locally intensified to 1.5 times the design width, and the backpressure cover thickness is increased to 15m. At the same time, the earthwork transportation route is clarified, the storage of riprap and cover materials and equipment commissioning are completed, and a three-dimensional geological model visualization briefing is conducted for construction personnel. The construction is carried out using the advance occupation method, advancing from small mileage to large mileage along the centerline of the cofferdam, and expanding horizontally to the design width, which is 4m at the top. After the riprap is 30cm above the water surface, a 20t excavator is used to repeatedly roll it along a "Z" path for 6-8 times until the riprap layer sinks ≤5mm / 12h. After the cofferdam slope is sloped at 1:1.5, 240g / m² polypropylene woven cloth is laid with an overlap length of ≥1m. U-shaped nails are used to fix it in a 2m×2m plum blossom shape to prevent water infiltration and slope scouring. The riprap particle size is controlled at 30-50cm and the mud content is ≤3%; the elevation error of the cofferdam top is ±50mm, and the axis deviation is ≤100mm; after the accumulated water is pumped out, the silt at the bottom of the reservoir is removed to the hard soil layer, and the silt is cleared to a depth of ≥1.2m. After the silt is dried, it is backfilled to a non-load-bearing area 15m outside the tunnel axis. The slurry is spread in a segmented stepped manner, and the thickness of each layer is ≤300mm. In the mechanical compaction area, an 18t vibratory roller is used to compact the land 3-4 times in a "vertical first, then horizontal" trajectory. In the corner area, a flat plate compactor is used to compact the land 6-8 times in layers. After each layer is compacted, the ring knife method is used to test the compaction degree to be ≥90%. After the filling is completed, a static load test is carried out, and the characteristic value of the foundation bearing capacity is ≥150kPa. A test section is set up 30m before the crossing to collect real-time data of thrust 2500-3700t, torque 1700-2600kN·m, and penetration 30-40mm / r and other data, a parameter-settlement correlation model was established through machine learning algorithms. The "shield brain" system was used to monitor parameters such as soil bin pressure of 1.0-1.1 bar and grouting volume of 1.28-1.3 times the theoretical value in real time. The warning threshold was automatically triggered if the soil pressure fluctuation was greater than 0.05 bar / min. A cement-water glass dual liquid slurry with a volume ratio of 1:1 was used, and the initial setting time was controlled at 45-60 seconds. A water stop ring was installed every 5 rings, and the grouting pressure was 0.3-0.5 MPa. At the most unfavorable locations of points 2-5 and 7-10 on the left tunnel, Φ42 grouting holes with a depth of 1.2m were drilled and cement-water glass slurry was injected with a water-cement ratio of 1:1, a Baume degree of 38°Bé, and a grouting volume of 0.3m³ / ring. A 400MHz antenna was used for ground scanning, with a horizontal survey line spacing of 0.5m and profiles set every 10m in the longitudinal direction. The soil disturbance areas with a dielectric constant greater than 15 and seepage channels were identified. Sleeve valve pipe grouting was implemented in the identified seepage channels with a grouting pressure of 0.5-0.8MPa and a diffusion radius of 1.5m. In the earth pressure balance mode, the speed was reduced to 80% of the left line, the cutterhead speed was 1.0-1.2r / min, the soil bin pressure was increased by 10%, polyurethane sealing grease was continuously injected, and bentonite slurry was injected into the soil bin to form a thick 20m or thicker seepage channel. m of low-permeability mud membrane, and immediately embed 300mm×300mm sponge strips with an overlap length of 100mm in case of leakage. The shield tail grease pumping pressure is increased to 4MPa; automated monitoring points are arranged to collect real-time data such as surface settlement, segment convergence, and pore water pressure. After the crossing is completed, continuous monitoring is carried out within a range of 1000m for 60 days. The data stability standard is: surface daily settlement ≤0.2mm / d, segment convergence rate ≤0.05mm / d, and seepage volume ≤0.1L / m²·d. The monitoring data is processed by cubic spline interpolation to generate a displacement contour map. When the coefficient of variation is <5%, it is handed over to the operating unit, and a full life cycle digital twin model is established. The above is the working principle of this shield efficient crossing reservoir stability analysis and safety control construction method.

Claims

1. A shield tunneling high-efficiency reservoir crossing stability analysis and safety control construction method, characterized by: The following steps are involved: S1. Pre-construction preparation and geological survey: Use HSP technology to survey the geology in front of the tunnel face 20m before the shield tunnel crosses the water, identify risk points, and optimize the design of the riprap and silt removal range and backpressure cover thickness based on the geological conditions; S2. Rock dumping and cofferdam construction: Rock dumping is carried out along the centerline of the cofferdam from smaller to larger mileages, expanding in layers to the designed width. Rock dumping is carried out 30 cm above the water surface and then repeatedly compacted using the excavator's own weight. When the amount of silt subsided approaches zero, rocks are added to the designed elevation. Polypropylene woven cloth is laid on the cofferdam slope. S3. Backfill and compaction of back-pressure soil in layers: After draining, remove the silt from the reservoir bottom to the hard soil layer, dry the silt and backfill it to the non-load-bearing area. Use segmented and layered stepped paving and compaction to backfill in layers. S4, Left-line shield tunneling parameter control and information management: A test section is set up 30m before the underpass to collect thrust, torque, and excavation data in real time to optimize tunneling parameters, establish a historical database, automatically warn of deviations from preset thresholds, and synchronize grouting and water stop ring installation; S5. Pre-reinforcement of the left-line tunnel before the second crossing of the right line: radial grouting of the left-line tunnel segments. Daily ground radar scanning during the right-line crossing to identify soil disturbances and seepage channels. S6, dynamic control and emergency blocking of right-line shield tunneling: tunneling in earth pressure balance mode, with the speed reduced to 80% of the left-line speed, continuous injection of polymer sealing grease, and injection of bentonite slurry into the soil bin to form a low-permeability mud film; S7. Post-construction stability monitoring and evaluation: Establish a multi-dimensional monitoring system, and continuously monitor within a range of 1000m for 60 days after the crossing is completed. After the data stabilizes, it will be handed over to the operating unit.

2. A shield tunneling high-efficiency reservoir crossing stability analysis and safety control construction method according to claim 1, characterized in that: In step S1, the logical steps of the HSP technology are: ； in, represents the frequency domain response; It represents the quantitative difference in wave impedance at the interface between two media, which determines the proportion of reflected energy; It represents the two-way travel time of the reflected wave described by the pulse function, which is used to locate the depth d of the geological interface; t represents the total time from the excitation to the reception of the reflected wave; v1 represents the P-wave velocity of the first medium; v2 represents the P-wave velocity of the second medium; Indicates the distance between the excitation point and the receiving point; represents the apparent velocity; It means converting the time domain signal into the frequency domain; finally, the inversion imaging of the stratigraphic structure is achieved through the joint analysis of time and frequency.

3. The method for analyzing the stability and controlling the safety of a shield tunnel crossing a reservoir with high efficiency according to claim 1 is characterized by: In step S2, the riprap and silt removal are carried out by using an excavator and manual labor to simultaneously construct two cofferdams. The riprap sequence is to throw the silt forward along the center line of the cofferdam and then expand horizontally to both ends in sequence. The slope of both sides of the cofferdam is 1:1.

5.

4. The method for analyzing stability and controlling safety of a shield tunneling machine for efficient reservoir crossing according to claim 1 is characterized by: In step S3, the plane range of the segmented and layered stepped paving and compacting construction is 10m outward on both sides of the tunnel cross section, and both sides of the longitudinal section are connected to the road through a gentle fill slope. The backfill corners and areas that cannot be compacted mechanically are compacted with a flat plate compactor, and other areas are mechanically leveled with a vibratory roller.

5. The method for analyzing the stability and controlling the safety of a shield tunnel crossing a reservoir with high efficiency according to claim 1 is characterized by: In step S3, the plane construction scope of the segmented and layered stepped paving and compacting construction is limited to 10m on both sides of the tunnel cross section, and the longitudinal section is smoothly connected to the existing road by slowing down the fill slope. The corners and areas that cannot be compacted by machinery are compacted by flat plate compactors, and other areas are compacted by vibratory rollers in layers. The filling sequence is longitudinal paving. During the segmented and layered stepped paving and compacting construction, dump trucks are used to transport soil to the bottom of the reservoir bank, and excavators are used to spread the soil from the middle to both sides. The virtual paving thickness is completed by first longitudinal and then transverse rolling. Each layer of backfill is compacted continuously on the same day, and drainage measures are set up.

6. The method for analyzing the stability and controlling the safety of a shield tunnel crossing a reservoir with high efficiency according to claim 1 is characterized by: In step S4, the thrust, torque, earth pressure, grouting volume and synchronous posture data of the shield cutter head are collected in real time using an information platform. The preset thresholds are total thrust ≤ 3700t, torque ≤ 2600kN.m, and excavation coefficient ≤ 1.

3. The real-time data are dynamically compared with the preset thresholds, and a three-level early warning mechanism is established for automatic early warning. The three-level early warning mechanism is as follows: A deviation of 5%-10% from the preset threshold triggers a yellow warning; A deviation of 10%-15% from the preset threshold triggers an orange warning; A deviation of >15% from the preset threshold triggers a red shutdown command.

7. The method for analyzing stability and controlling safety of a shield tunneling machine for efficient reservoir crossing according to claim 1 is characterized by: In step S4, the synchronous grouting control adds 4% concentration of water glass as a coagulant to the grouting material, and the mixing ratio of the grouting material and the water glass is: 1:

1. A grouting operation is performed after the pipe segment is removed from the shield tail and after the water stop ring is set. The water stop ring is set every 5 rings of tunnel excavation.

8. The method for analyzing stability and controlling safety of a shield tunneling machine for efficient reservoir crossing according to claim 1 is characterized by: In step S5, grouting is performed on the most unfavorable points of the 20-ring formed tunnel segments before and after the left-line water area. The slurry type used is cement-water glass slurry. For the right-line crossing area, high-frequency electromagnetic waves are emitted into the ground by radar. The radar accurately records the reflected electromagnetic waves to form a cross-sectional scan image to determine the actual situation of the underground target.

9. The method for analyzing stability and controlling safety of a shield tunneling machine for efficient reservoir crossing according to claim 1 is characterized by: In step S6, shield tail sealing grease is continuously injected during the crossing, and the shield tail sealing grease is continuously pumped until there is no leakage before continuing the excavation. The leakage is eliminated by a dedicated person through the sponge strips provided on site that are embedded in the gap between the shield tail shell and the pipe segment along the entire circumference.

10. The method for analyzing stability and controlling safety of a shield tunneling machine for efficient reservoir crossing according to claim 1, characterized in that: In step S7, the multi-dimensional monitoring system includes geological condition monitoring dimension, construction parameter monitoring dimension, structural safety monitoring dimension, surface environment monitoring dimension and long-term stability monitoring dimension. The risk level is divided according to the monitoring results of the multi-dimensional monitoring system, so that the tunnel is reinforced accordingly.

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