Synchronous grouting method behind the segment wall for dual-shield TBMs

Abstract

This invention belongs to the field of tunnel boring machine (TBM) construction technology, specifically relating to a method for synchronous grouting behind the tunnel lining segments in a double-shield TBM. This method aims to solve the problems of poor matching between grout setting time and real-time working conditions, and difficulty in dynamically adjusting grouting parameters in existing double-shield TBM tunneling. Key technical points: The cutterhead torque and tunneling speed are each divided into three intervals and combined into nine working conditions. For each working condition, the target setting time is calculated using the formula T = k × L / v. The target volume ratio is obtained through the volume ratio-setting time curve and a mapping table is pre-stored. During tunneling, torque and speed are monitored in real time to determine the current working condition combination. The target volume ratio is retrieved to control the mixing ratio of liquid A and liquid B. The grouting volume is determined by multiplying the theoretical volume of the annular gap by the filling coefficient based on the real-time tunneling speed. The grouting pressure is maintained at 1.05-1.15 times the water and soil pressure of the surrounding rock at the grouting point. Its main application is to achieve adaptive dynamic control of synchronous grouting parameters behind the tunnel lining segments in a double-shield TBM.

Description

Technical Field

[0001] This invention belongs to the field of tunnel boring machine (TBM) technology. More specifically, this invention relates to a method for simultaneous grouting behind the segment walls of a double-shield TBM. Background Technology

[0002] During the construction of a dual-shield tunnel boring machine (TBM), after precast concrete segments are assembled into a ring, an annular gap exists between the outer wall of the segment and the surrounding rock of the excavated tunnel. To ensure the stability of the surrounding rock, control ground deformation, and provide timely support for the segment lining, grout material needs to be injected into this annular gap for filling. Commonly used grouting methods behind the segment wall include synchronous grouting and timely grouting through pre-reserved grouting holes in the segment. Under the conditions of a dual-shield TBM, due to the structural characteristics of the equipment, the shield tail length is limited, and the shield provides temporary support to the surrounding rock. Before the segment exits the shield tail, grout can be injected into the gap behind the wall through pre-reserved grouting holes to minimize the exposure time of the surrounding rock.

[0003] In actual construction, the gelling properties of grouting materials have a direct impact on the grouting effect. For grouting processes using two-component grouts, component A is usually a cement-based grout, and component B is a water glass solution. After mixing, the two react and lose their fluidity within a certain time to form a gel. If the gelling time is too short, the grout will solidify rapidly after injection, which may lead to insufficient grout flow distance, inadequate filling range, or even blockage of the grouting pipeline. If the gelling time is too long, the grout is prone to flow along the surrounding rock fissures or accumulate at lower levels under gravity before solidification, causing local voids behind the segments, uneven filling, and may also cause the segments to float or excessive ground settlement.

[0004] During the tunneling process of a dual-shield tunneling machine, the cutterhead torque and tunneling speed fluctuate with changes in surrounding rock conditions, machine load, and operating parameters. An increase in cutterhead torque usually indicates increased rock fragmentation or cutting resistance, while the tunneling speed directly affects the size of the newly formed annular gap per unit time. Maintaining a fixed target gelling time for the grout makes it difficult to adapt to grouting requirements under different combinations of torque and tunneling speed. For example, when the tunneling speed is high, the volume of the annular gap generated per unit time is large. If the grout gelling time remains unchanged, the grout may not have enough time to fully expand within the gap before solidifying, resulting in limited filling range. When the torque increases and the surrounding rock fragmentation is high, the risk of grout loss increases; if the gelling time remains set as originally intended, the loss may further increase. However, on-site adjustments to the gelling time often rely on the experience and judgment of technical personnel, lacking quantitative basis linked to real-time tunneling parameters, resulting in a lag and subjectivity in the adjustment process.

[0005] The main difficulty encountered in attempting to match the grout setting time with the tunneling conditions lies in the complex coordination between the shield tail geometry, the grout chemical reaction rate, and the tunneling speed. With a fixed shield tail length, the grout, after being transported from the mixing point to the injection hole and entering the annular gap, needs to reach sufficient strength to provide support before the segments exit the shield tail, while also ensuring adequate flow time after injection to complete filling. Setting a fixed setting time based solely on experience makes it difficult to account for variations in torque and speed throughout the tunneling process. At lower torque and slower speeds, the grout remains in the gap for a longer time; an excessively short setting time may result in incomplete filling and loss of fluidity. At higher torque and faster speeds, the gap formation rate is rapid, and the degree of surrounding rock fissure development may be higher; an excessively long setting time can exacerbate grout loss. Furthermore, the on-site construction environment limits frequent offline testing of the grout mix ratio, making it difficult to obtain accurate real-time correlations between setting time and volume ratio in each tunneling cycle.

[0006] Therefore, existing grouting control methods suffer from a disconnect between the setting of the gelling time and the response to the tunneling status, affecting the filling quality of the backfill grout and the control effect of the surrounding rock. Currently, there is a lack of a systematic and operable method that can be linked to tunneling parameters to determine a reasonable grout gelling time and corresponding mix ratio in real time based on changes in cutterhead torque and tunneling speed. Summary of the Invention

[0007] The purpose of this invention is to provide a method for synchronous grouting behind the segment wall of a double-shield TBM, in order to solve the technical problems of fixed grout setting time and difficulty in adapting to dynamic changes in cutterhead torque and tunneling speed in existing grouting methods, so that grouting parameters can be quantitatively linked and adjusted with the real-time tunneling status.

[0008] To address the aforementioned problems and achieve the objectives and other advantages of this invention, a method for synchronous grouting behind the segment walls of a double-shield TBM is provided, characterized by comprising the following steps: Inside the tail of the double-shield TBM, a dual-liquid grout is injected into the annular gap between the outer wall of the segment and the surrounding rock through pre-reserved injection holes on the segment before the segment is assembled and before it detaches from the tail. The dual-liquid grout consists of liquid A and liquid B, where liquid A is a cement-based grout and liquid B is a water glass solution. After being mixed in a mixer via their respective delivery pipelines, liquids A and B are sent to the injection holes through the injection pipeline and injected into the annular gap. During the injection process, the injection pressure is maintained at 1.05-1.15 times the water and soil pressure of the surrounding rock at the injection point. Before tunneling with the dual-shield TBM, the cutterhead torque of the dual-shield TBM is divided into a first torque range, a second torque range, and a third torque range. The first torque range is ≤1000 kN·m, 1000 kN·m < the second torque range ≤1500 kN·m, and the third torque range >1500 kN·m. The tunneling speed of the dual-shield TBM is divided into a first tunneling speed range, a second tunneling speed range, and a third tunneling speed range. The first tunneling speed range is ≤40 mm / min, 40 mm / min < the second tunneling speed range ≤60 mm / min, and the third tunneling speed range >60 mm / min. The above three torque ranges and three tunneling speed ranges are combined in pairs to form nine working condition combinations. For each working condition combination, the target gelling time T is calculated using the formula T = k × L / v, where L is the shield tail length, v is the tunneling speed in the corresponding tunneling speed range, and k is the safety factor. When the working condition combination corresponds to the first torque range, k is 0.8; when it corresponds to the second torque range, k is 0.6; and when it corresponds to the third torque range, k is 0.4. The target gelling time T is input into the pre-established volume ratio-gelling time correspondence curve, and the target volume ratio is obtained by reverse lookup. Thus, an initial volume ratio mapping table is established, which corresponds one-to-one with the nine working condition combinations and the nine target volume ratios, and is pre-stored in the control system of the dual-shield TBM. During the tunneling process of the dual-shield TBM, the cutterhead torque and the real-time tunneling speed are detected in real time to determine the working condition combination corresponding to the current torque range and tunneling speed range. The target volume ratio corresponding to the current working condition combination is retrieved from the initial volume ratio mapping table, and the mixing ratio of liquid A and liquid B is controlled according to the target volume ratio. The theoretical volume of the newly formed annular gap per unit time is calculated based on the real-time tunneling speed. The theoretical volume is then multiplied by the filling coefficient to obtain the injection volume of the two-liquid grout per unit time. The filling coefficient is 1.2-1.8.

[0009] Preferably, in the method for synchronous grouting behind the tunnel lining wall of a dual-shield TBM, during the tunneling process of the dual-shield TBM, the displacement of the tunnel lining segment that has detached from the shield tail is detected in real time. When the displacement is settlement and the settlement exceeds a preset settlement threshold, the target volume ratio corresponding to the current working condition combination in the initial volume ratio mapping table is reduced by a preset correction step size to obtain the corrected target volume ratio. The corrected target volume ratio replaces the original target volume ratio of the working condition combination in the initial volume ratio mapping table. When the displacement is an upward float and the upward float exceeds the preset upward float threshold, the target volume ratio corresponding to the current working condition combination in the initial volume ratio mapping table is increased by the preset correction step size to obtain the corrected target volume ratio, and the original target volume ratio of the working condition combination in the initial volume ratio mapping table is replaced with the corrected target volume ratio. The preset correction step size ranges from 0.5 to 2.0.

[0010] Preferably, in the method for synchronous grouting behind the segment wall of a dual-shield TBM, the materials of liquid A include cement and water, and liquid B is a water glass solution, the parameters of which include modulus and Baumé degree; The volume ratio-gelling time relationship curve was established through the following steps: In the indoor test, the type and grade of cement in liquid A and the water-cement ratio of cement paste were fixed, and the modulus and Baumé degree of water glass in liquid B were fixed. Multiple sets of different volume ratios of liquid A to liquid B were set up, and the gelation time corresponding to each volume ratio was determined by the inverted cup method. Plot the volume ratio as the x-axis and the gelation time as the y-axis, and draw a scatter plot of the data of each group of volume ratios and gelation times. Then, obtain the corresponding curve of volume ratio-gelation time by curve fitting.

[0011] Preferably, in the method for synchronous grouting behind the segment walls of a dual-shield TBM, the rock integrity coefficient K is obtained through acoustic testing during the tunneling process of the dual-shield TBM. v ; When K v When the value is less than 0.20, the safety factor k is reduced by 0.30. When 0.20≤K v When the value is less than 0.40, the safety factor k is reduced by 0.15. When 0.40≤K v When the value is less than 0.60, the value of the safety factor k is not adjusted. When 0.60≤K v When the value is less than 0.80, the safety factor k is increased by 0.10. When K v When the value is ≥0.80, the safety factor k is increased by 0.20; The target gelling time T is recalculated based on the adjusted safety factor k, and the adjusted target gelling time T is input into the pre-established volume ratio-gelling time correspondence curve to obtain the corrected target volume ratio. The corrected target volume ratio is then used to update the target volume ratio corresponding to the current working condition combination in the initial volume ratio mapping table.

[0012] Preferably, in the method for synchronous grouting behind the segment wall of a double-shield TBM, the groundwater corrosivity level at the current tunneling location is obtained in real time during the tunneling process of the double-shield TBM. When the groundwater corrosivity level is slightly corrosive, the Baumé degree of the water glass solution is increased by 0-1°Bé from the original Baumé degree. When the groundwater corrosivity level is weak, the Baumé degree of the water glass solution is increased by 1-3°Bé from the original Baumé degree. When the groundwater corrosivity level is moderate, the Baumé degree of the water glass solution should be increased by 3-5°Bé from the original Baumé degree. When the groundwater corrosivity level is strong, the Baumé degree of the water glass solution is increased by 5-8°Bé from the original Baumé degree. After adjusting the Baumé degree, the modulus of the water glass solution remains unchanged. The adjusted water glass solution is then used as solution B, mixed with solution A, and injected into the annular gap.

[0013] Preferably, in the method for synchronous grouting behind the segment walls of a dual-shield TBM, the rock integrity coefficient K is obtained through acoustic testing during the tunneling process of the dual-shield TBM. v ; When K v When <0.20, the filling coefficient should be 1.6-1.8; When 0.20≤K v When <0.40, the filling coefficient should be 1.5-1.7; When 0.40≤K v When <0.60, the filling coefficient should be 1.3-1.5; When 0.60≤K v When <0.80, the filling coefficient should be 1.2-1.3; When K v When the value is ≥0.80, the filling coefficient is taken as 1.2.

[0014] Preferably, in the method for synchronous grouting behind the segment wall of a double-shield TBM, a density detection unit is installed on the grouting pipeline during the tunneling process of the double-shield TBM, and the density of the mixed two-liquid grout is detected in real time by the density detection unit. Before the double-shield TBM tunneling, a density-volume ratio relationship curve was pre-established through indoor tests. The establishment method was as follows: The type and grade of cement in liquid A and the water-cement ratio of cement paste are fixed, and the modulus and Baumé degree of water glass in liquid B are fixed. Set up multiple sets of different volume ratios of liquid A to liquid B, and measure the density of the mixed two-liquid slurry corresponding to each volume ratio; Plot the volume ratio as the x-axis and the density as the y-axis, and draw a scatter plot of the volume ratio and density data for each group. Obtain the density-volume ratio relationship curve through curve fitting. During the tunneling process of the dual-shield TBM, the real-time detected density is converted into the actual volume ratio through the density-volume ratio correspondence curve; When the actual volume ratio is greater than the target volume ratio and the deviation exceeds the preset deviation threshold, reduce the output flow rate of the A liquid grouting pump or increase the output flow rate of the B liquid grouting pump until the deviation between the actual volume ratio and the target volume ratio is less than or equal to the preset deviation threshold. When the actual volume ratio is less than the target volume ratio and the deviation exceeds the preset deviation threshold, increase the output flow rate of the A liquid grouting pump or decrease the output flow rate of the B liquid grouting pump until the deviation between the actual volume ratio and the target volume ratio is less than or equal to the preset deviation threshold. The output flow rate of the grouting pump can be adjusted by using a frequency converter to adjust the motor speed, a speed control valve to adjust the hydraulic oil flow rate, or a PLC controller to adjust the stroke length. The adjustment range in a single instance shall not exceed ±5% of the current output flow rate of the grouting pump. The preset deviation threshold is ±0.2 to ±0.5 of the target volume ratio.

[0015] Preferably, in the method for synchronous grouting behind the segment wall of a double-shield TBM, the grouting pressure is monitored in real time during the tunneling process of the double-shield TBM. When the grouting pressure is greater than 1.15-1.30 times the water and soil pressure of the surrounding rock at the grouting point, an alarm signal is issued, but the delivery of liquid A and liquid B is not stopped. When the grouting pressure is greater than or equal to 1.30 times the water and soil pressure of the surrounding rock at the grouting point, the delivery of liquid A and liquid B shall be stopped immediately and an alarm signal shall be issued.

[0016] Preferably, in the method for synchronous grouting behind the segment wall of a double-shield TBM, the grouting pressure and the real-time tunneling speed are monitored in real time during the tunneling process of the double-shield TBM. When the grouting pressure rises by more than 0.10 MPa within 30 seconds and the real-time tunneling speed changes by less than 5% within the same time period, it is determined that there is a risk of blockage in the grouting pipeline and an alarm signal is issued.

[0017] Preferably, in the method for synchronous grouting behind the segment wall of a dual-shield TBM, the materials of liquid A include cement, water, and bentonite, the weight ratio of water to cement in liquid A is 0.8-1.2:1, and the bentonite in liquid A accounts for 2%-6% of the weight of cement. Solution B is a water glass solution with a modulus of 2.4-3.4 and a Baumé degree of 30-45°Bé.

[0018] The present invention has at least the following beneficial effects: This invention divides the cutterhead torque and tunneling speed into three intervals and combines them in pairs to form nine working condition combinations. For each working condition combination, the target gelation time is calculated according to a formula, and the target volume ratio is looked up. An initial volume ratio mapping table is pre-stored in the control system, establishing a clear quantitative linkage between the grouting mix setting and the tunneling status. During tunneling, the torque and speed are monitored in real time to automatically retrieve the appropriate target volume ratio, avoiding the lag and subjective errors caused by relying on manual experience. This allows the gelation time of the two-component grout to be adjusted in a timely manner according to changes in working conditions, improving the response speed and control accuracy of backfill grouting to dynamic tunneling conditions.

[0019] This invention, while retrieving the target volume ratio, calculates the theoretical volume of the newly formed annular gap based on the real-time tunneling speed and multiplies it by the filling coefficient to determine the grouting volume, while maintaining the grouting pressure within the range of 1.05-1.15 times the water and soil pressure of the surrounding rock at the grouting point. This method keeps the grout supply per unit time synchronized with the gap formation rate, and the pressure control ensures both filling power and prevents surrounding rock splitting or abnormal segment stress, thereby improving the continuity and uniformity of annular gap filling and reducing the risks of voids, ground subsidence, and segment floating caused by insufficient or excessive injection.

[0020] This invention monitors the displacement of segments that have detached from the shield tail in real time during tunneling. When settlement or uplift exceeds limits, it corrects the target volume ratio for the corresponding working condition in the initial volume ratio mapping table by decreasing or increasing the target volume ratio, and replaces the original value with the corrected value for subsequent similar working conditions. This closed-loop feedback mechanism incorporates the actual attitude changes of the segments into the grouting ratio adjustment, enabling the grouting parameters to adaptively optimize in response to ground deformation, gradually approaching the optimal grouting ratio under the current geological conditions. This effectively suppresses the displacement development in the early stage of segment detachment from the shield tail and reduces the incidence of secondary problems such as segment misalignment, joint leakage, and axial deviation.

[0021] This invention uses indoor experiments to fix the material parameters of liquid A and liquid B, sets multiple sets of volume ratios to measure gelation time, and fits the volume ratio-gelation time correspondence curve to obtain a specific basis for the accurate conversion from target gelation time to target volume ratio. By using a material formula completely consistent with actual construction to establish the curve, deviations in gelation characteristics caused by differences in cement type, water-cement ratio, water glass modulus, and Baume degree are eliminated. This ensures a high degree of consistency between the mix proportion instructions and the actual grout reaction law, thereby improving the stability and repeatability of grouting quality.

[0022] This invention obtains the surrounding rock integrity coefficient K through acoustic testing during the tunneling process of a dual-shield TBM. v And according to K vThe safety factor k is adjusted by increasing or decreasing according to the classification, and the target gelling time and volume ratio are recalculated and updated. This measure incorporates the integrity of the surrounding rock into the correction of the safety factor, so that the setting of the grout gelling time is further coordinated with the degree of rock fragmentation on the basis of the torque range. The gelling time is shortened in the fragmented section to inhibit the loss of grout along the cracks, and the gelling time is appropriately extended in the intact section to ensure full filling, thereby enhancing the adaptability of the grouting scheme to surrounding rock with different integrity.

[0023] This invention acquires the groundwater corrosivity level at the tunneling location in real time and increases the Baume degree of the water glass solution according to the degree of erosion, while maintaining the modulus unchanged. Increasing the Baume degree increases the silica gel content and density in the grout aggregate, improving its resistance to chemical corrosion. This ensures that the durability of the backfill layer in different corrosive groundwater environments matches the actual risks, avoiding long-term leakage and deterioration due to insufficient durability in highly eroded sections, and also avoiding material waste and pumping difficulties caused by excessively high Baume degrees in slightly eroded sections.

[0024] This invention obtains the surrounding rock integrity coefficient K through acoustic wave testing. v The filling coefficient was adjusted in stages to dynamically change the grouting volume per unit time according to the degree of surrounding rock fragmentation. The filling coefficient was increased in the fragmented surrounding rock section to compensate for over-excavation and fracture loss, while the filling coefficient was decreased in the intact surrounding rock section to prevent excessive grouting. This made the actual grout injection volume more accurately match the volume that the surrounding rock could accommodate, reducing material waste or incomplete filling caused by a fixed filling coefficient, and improving the utilization rate of grouting materials and the consistency of backfill quality.

[0025] This invention installs a density detection unit on the grouting pipeline and pre-establishes a density-volume ratio correlation curve. During tunneling, the actual volume ratio is calculated online by density detection and compared with the target volume ratio. If a deviation occurs, the output flow rate of either liquid A or liquid B grouting pump is automatically adjusted. This online feedback adjustment mechanism overcomes the proportioning deviation caused by pumping system disturbances under open-loop control, enabling the actual injected volume ratio to track the target value in real time. This ensures the accurate realization of the gelation time under actual construction conditions, improving the robustness of proportioning control and the stability of grouting quality.

[0026] This invention sets two levels of monitoring thresholds for grouting pressure. When the pressure exceeds 1.15-1.30 times the surrounding rock water and soil pressure, an alarm is issued but grouting is not stopped, providing operators with a buffer time for early warning and intervention. When the pressure reaches or exceeds 1.30 times the pressure, grouting is immediately stopped and an alarm is triggered to prevent overpressure damage to the shield tail seal or segment structure. This tiered response mechanism establishes a safety protection barrier while ensuring construction continuity, effectively reducing the risk of overpressure accidents caused by pipeline blockage or abnormal injection.

[0027] This invention simultaneously detects grouting pressure and tunneling speed. When the pressure rises by more than 0.10 MPa within 30 seconds and the tunneling speed changes by less than 5%, it determines the risk of pipeline blockage and issues an alarm. This combined criterion filters out interference from normal pressure fluctuations caused by changes in tunneling parameters, enabling early warning at the initial stage of blockage. This provides operators with time to clear the pipeline, switch to backup lines, or adjust grouting parameters, reducing downtime and construction interruptions caused by pipeline blockage and improving the operational reliability of the grouting system.

[0028] Other advantages, objectives and features of the present invention will become apparent in part from the following description, and in part from those skilled in the art through study and practice of the invention. Attached Figure Description

[0029] Figure 1 This is a flowchart of the synchronous grouting process behind the segment walls of a double-shield TBM. Detailed Implementation

[0030] The present invention will now be described in further detail so that those skilled in the art can implement it based on the description.

[0031] It should be noted that, unless otherwise specified, the experimental methods described in the following implementation plan are all conventional methods, and the reagents and materials described are all commercially available unless otherwise specified.

[0032] like Figure 1 As shown, the present invention provides a method for synchronous grouting behind the segment wall of a double-shield TBM, comprising the following steps: Inside the tail of the double-shield TBM, a dual-liquid grout is injected into the annular gap between the outer wall of the segment and the surrounding rock through pre-reserved injection holes on the segment before the segment is assembled and before it detaches from the tail. The dual-liquid grout consists of liquid A and liquid B, where liquid A is a cement-based grout and liquid B is a water glass solution. After being mixed in a mixer via their respective delivery pipelines, liquids A and B are sent to the injection holes through the injection pipeline and injected into the annular gap. During the injection process, the injection pressure is maintained at 1.05-1.15 times the water and soil pressure of the surrounding rock at the injection point. Before tunneling with the dual-shield TBM, the cutterhead torque of the dual-shield TBM is divided into a first torque range, a second torque range, and a third torque range. The first torque range is ≤1000 kN·m, 1000 kN·m < the second torque range ≤1500 kN·m, and the third torque range >1500 kN·m. The tunneling speed of the dual-shield TBM is divided into a first tunneling speed range, a second tunneling speed range, and a third tunneling speed range. The first tunneling speed range is ≤40 mm / min, 40 mm / min < the second tunneling speed range ≤60 mm / min, and the third tunneling speed range >60 mm / min. The above three torque ranges and three tunneling speed ranges are combined in pairs to form nine working condition combinations. For each working condition combination, the target gelling time T is calculated using the formula T = k × L / v, where L is the shield tail length, v is the tunneling speed within the corresponding tunneling speed range, and k is the safety factor. When the working condition combination corresponds to the first torque range, k is 0.8; for the second torque range, k is 0.6; and for the third torque range, k is 0.4. The target gelling time T is input into a pre-established volume ratio-gelling time correspondence curve, and the target volume ratio is obtained by reverse lookup. This establishes an initial volume ratio mapping table with nine working condition combinations and nine target volume ratios, which is pre-stored in the control system of the dual-shield TBM. It should be noted that the target gelling time T, in an engineering sense, corresponds to the initial setting time of the cement-water glass slurry. For cement-water glass slurry, it typically maintains a flowable period of at least 20-30 seconds before initial setting, which can meet the short-distance flow and distribution requirements after injection. Therefore, by limiting the target initial setting time, the technical effect of flow during injection and rapid support after exiting the shield tail can be achieved. The effective grouting length L at the shield tail is defined as the distance from the last grouting hole on the segment to the end of the shield tail along the tunneling direction. The tunneling speed v used in the formula T = k × L / v is the current real-time monitored value. Its physical meaning is that there is a one-to-one spatial correspondence between the newly formed annular gap at the current moment and the grout injected at the current moment. Since the effective grouting length L at the shield tail is typically 3.5-5.5m, under common tunneling speeds of 40-60mm / min, the time it takes for any grouting hole on the segment to enter and exit the shield tail is relatively short, and the change in tunneling speed within this time window is limited. Therefore, using the real-time monitored v value as the basis for calculating the grouting parameters corresponding to the gap formed at that moment is both reasonable and feasible in engineering terms. If the tunneling speed fluctuates drastically in a short period (e.g., the change exceeds 20%), the control system will automatically re-determine the working condition combination and update the target volume ratio, thereby ensuring continuous tracking of the tunneling status by the grout setting time.

[0033] During the tunneling process of the dual-shield TBM, the cutterhead torque and the real-time tunneling speed are detected in real time to determine the working condition combination corresponding to the current torque range and tunneling speed range. The target volume ratio corresponding to the current working condition combination is retrieved from the initial volume ratio mapping table, and the mixing ratio of liquid A and liquid B is controlled according to the target volume ratio. The theoretical volume of the newly formed annular gap per unit time is calculated based on the real-time tunneling speed. The theoretical volume is then multiplied by the filling coefficient to obtain the injection volume of the two-liquid grout per unit time. The filling coefficient is 1.2-1.8.

[0034] The closest existing technology involves using a fixed-ratio two-component grout for simultaneous grouting behind the tunnel lining segments in double-shield TBM construction. Before construction, a volume ratio of liquid A to liquid B is selected based on experience or simple experiments and remains constant throughout the process. The grouting volume is typically determined by multiplying the theoretical annular gap volume by an empirical coefficient, and the grouting pressure is adjusted manually. In this method, the grout's gelation time is a fixed value and fails to respond to changes in cutterhead torque and tunneling speed. When the tunneling speed decreases, the fixed gelation time may cause the grout to gel before it has fully flowed within the gap, resulting in insufficient filling and localized voids. When the torque increases, indicating more fractured surrounding rock, the fixed gelation time may lead to excessive grout loss along the fractures due to prolonged fluidity. While on-site technicians can manually adjust the ratio, there is a lack of quantitative data linking it to real-time tunneling parameters. The timing and extent of adjustments rely on personal experience, making it difficult to achieve consistently stable grouting quality under dynamically changing conditions.

[0035] This invention divides the cutterhead torque into a first torque range (not exceeding 1000 kN·m), a second torque range (greater than 1000 kN·m and not exceeding 1500 kN·m), and a third torque range (greater than 1500 kN·m). Simultaneously, it divides the tunneling speed into a first tunneling speed range (not exceeding 40 mm / min), a second tunneling speed range (greater than 40 mm / min and not exceeding 60 mm / min), and a third tunneling speed range (greater than 60 mm / min). The invention then combines these three torque ranges and three speed ranges in pairs to form nine working condition combinations.

[0036] When calculating the target gelling time for each working condition combination, the safety factor k varies with the torque range: k is 0.8 for the first torque range, 0.6 for the second, and 0.4 for the third. Higher torque usually indicates poorer surrounding rock integrity or higher cutting resistance. In this case, reducing the safety factor shortens the calculated target gelling time, allowing the slurry to lose fluidity more quickly and reducing loss along fractures. The tunneling speed v is taken from the specific measured value within the given speed range, and the shield tail length L is an inherent parameter of the double-shield TBM equipment; for example, a common shield tail length is between 3.5 and 5.5 meters. The target gelling time T is calculated using the formula T = k × L / v, where k is the aforementioned safety factor, L is the shield tail length, and v is the real-time tunneling speed. After obtaining the target gelling time, it is input into a pre-established volume ratio-gelling time correlation curve from indoor tests to obtain the corresponding target volume ratio. The volume ratio refers to the ratio of the volume of liquid A to the volume of liquid B; a larger ratio usually indicates a longer gelling time. This led to the establishment of an initial volume ratio mapping table that corresponds one-to-one with the nine working condition combinations and the nine target volume ratios, which was pre-stored in the control system, thus completing the pre-setting preparation of grouting parameters for different working conditions before tunneling.

[0037] During tunneling, the cutterhead torque and tunneling speed are monitored in real time to determine the working condition combination corresponding to the current torque and speed ranges. The corresponding target volume ratio is directly retrieved from the initial volume ratio mapping table, and the output flow ratio of the A-liquid grouting pump and the B-liquid grouting pump is controlled according to this target volume ratio. Compared with manual judgment and adjustment, this step ensures timely response and clear basis for ratio switching, avoiding lag and subjective errors.

[0038] Meanwhile, the cross-sectional area of ​​the annular gap is calculated based on the difference between the tunnel excavation cross-section and the outer contour cross-section of the segment, which is π × (R 2 洞 - R² 管片 ), where R 洞 R is the shield excavation radius. 管片The cross-sectional area is the outer radius of the tunnel segment. Multiplying the real-time tunneling speed by the cross-sectional area gives the theoretical volume of the newly formed annular gap per unit time due to tunneling. Multiplying this theoretical volume by the filling coefficient gives the injection volume of the two-component grout per unit time. The filling coefficient is set to 1.2-1.8 to compensate for additional grout loss caused by over-excavation and cracks in the surrounding rock, as well as the calculation deviation of the void volume behind the tunnel segment. A faster tunneling speed results in a larger newly formed gap volume per unit time, and the injection volume increases accordingly; a slower speed results in a correspondingly smaller injection volume, maintaining basic synchronization between grout supply and gap formation rate. During grouting, the grouting pressure is maintained at 1.05-1.15 times the water and soil pressure of the surrounding rock at the grouting point. This pressure range ensures that the grout overcomes pipeline resistance and gap resistance to enter the space behind the wall, but is insufficient to cause surrounding rock splitting or excessive local stress on the tunnel segment. For example, when the measured water and soil pressure of the surrounding rock at the grouting point is 0.2 MPa, the grouting pressure should be controlled within the range of 0.21-0.23 MPa.

[0039] Example 1 The surrounding rock in a certain double-shield TBM construction section is mainly moderately weathered granite. The shield tail length L is 4.2m, the inner diameter of the shield tail is 6.7m, the outer diameter of the tunnel segment is 6.4m, and the designed thickness of the annular gap between the outer wall of the tunnel segment and the surrounding rock is 0.15m. Before construction, the cutterhead torque was divided into a first torque range not exceeding 1000kN·m, a second torque range greater than 1000kN·m but not exceeding 1500kN·m, and a third torque range greater than 1500kN·m in the control system. The tunneling speed was divided into a first tunneling speed range not exceeding 40mm / min, a second tunneling speed range greater than 40mm / min but not exceeding 60mm / min, and a third tunneling speed range greater than 60mm / min. These were combined in pairs to form nine working condition combinations.

[0040] In indoor experiments, the cement type in solution A was fixed as ordinary Portland cement grade 42.5 with a water-cement ratio of 0.8, and solution B had a water glass modulus of 2.8 and a Baumé degree of 35°Bé. Multiple sets of different volume ratios were used to measure the gelation time, and a volume ratio-gelation time correlation curve was plotted. For each working condition combination, the control system calculated the target gelation time using the formula T=k×L / v, where k was 0.8 for the first torque range, 0.6 for the second torque range, and 0.4 for the third torque range, and v was a representative value or actual measured value for that speed range. The calculated target gelation time for each working condition was input into the volume ratio-gelation time curve to obtain the corresponding target volume ratio, forming an initial volume ratio mapping table with nine working condition combinations and nine target volume ratios, which was pre-stored in the control system.

[0041] When the tunneling reached mileage DK12 + 345, the real-time measured cutterhead torque was 1350 kN·m, falling within the second torque range, and the real-time tunneling speed was 55 mm / min, falling within the second tunneling speed range. The control system automatically determined the safety factor k = 0.6 corresponding to the current working condition and calculated the target gelling time using the formula T = k × L / v, where v = 55 mm / min, i.e., 0.055 m / min, and T = 0.6 × 4.2 / 0.055 ≈ 45.8 min. Inputting 45.8 min into the pre-stored volume ratio-gelling time curve, the target volume ratio was found to be 3.2:1. Based on this, the control system set the flow ratio of the A-liquid grouting pump and the B-liquid grouting pump to 3.2:1 and injected the mixed two-liquid grout into the annular gap through the grouting holes reserved on the tunnel lining segments.

[0042] At this point, the real-time tunneling speed is 55 mm / min, the outer diameter of the tunnel segment is 6.4 m, and the designed thickness of the annular gap is 0.15 m. Taking the excavation radius as 3.35 m and the outer radius of the tunnel segment as 3.2 m, the cross-sectional area of ​​the annular gap = π × (3.35) 2 - 3.2 2 ≈3.08m 2 The theoretical volume of the newly formed annular gap per minute is the aforementioned cross-sectional area multiplied by the real-time tunneling speed, which is 3.08m. 2 ×0.055m / min ≈ 0.169m 3 / min. The filling coefficient is taken as 1.5 based on the degree of joint development in this section of surrounding rock, therefore the injection volume per unit time is controlled at 0.169m. 3 / min × 1.5 = 0.254m 3 / min, actually taken as 0.25m 3 / min. During the grouting process, the water and soil pressure of the surrounding rock at the grouting point was measured to be 0.18 MPa, and the grouting pressure was stably maintained between 0.19 and 0.21 MPa, which is consistent with the relationship of 1.05 to 1.15. After the ring segment detached from the shield tail, ground-penetrating radar detection showed that the annular gap behind the wall was fully and continuously filled, and no obvious cavities or grout-rich areas were found. The surface settlement monitoring value was 5.3 mm.

[0043] Comparative Example 1 For adjacent mileage sections DK12 + 360 to DK12 + 375 within the same construction zone, the same A and B liquid materials as in Example 1 were used: liquid A was ordinary Portland cement grout with a water-cement ratio of 0.8, and liquid B was a water glass solution with a modulus of 2.8 and a Baume degree of 35°Bé. Before construction, no torque-speed range division or volume ratio mapping table was established; instead, a fixed volume ratio of 4.0:1 was used for grouting throughout the entire process, with the corresponding setting time remaining constant at approximately 65 minutes as determined in laboratory tests. During grouting, the injection volume was not dynamically calculated based on the real-time tunneling speed, but rather based on a fixed value of 0.35m. 3 Grouting continued at a rate of 1420 kN·m / min. When tunneling reached DK12 + 368, the real-time measured cutterhead torque was 1420 kN·m, falling within the second torque range, and the tunneling speed was 52 mm / min, also falling within the second tunneling speed range. Because the safety factor and target setting time were not adjusted according to the torque, the grout remained flowable for 65 minutes after injection. The surrounding rock in this section had well-developed joints and fissures, and some grout flowed along these fissures to deeper layers of the surrounding rock under gravity. The grouting pressure fluctuated between 0.17 and 0.20 MPa but failed to establish effective filling pressure. After the segments emerged from the shield tail, inspection by tapping and drilling revealed localized cavities in the top area behind the segments, with a maximum cavity thickness of 8 mm and a corresponding angle range of approximately 40°. The surface settlement monitoring value for this section was 7.1 mm, approximately 34% higher than in Example 1, and the settlement stabilization time was extended by approximately 2 days. Subsequent secondary grouting treatment is required for this section, increasing the process time and material consumption.

[0044] A comparison of Example 1 and Comparative Example 1 shows that Example 1, by dividing torque and speed ranges, pre-setting a volume ratio mapping table, and dynamically adjusting the mix ratio and injection volume in real time, achieved a good match between the grout setting time and the tunneling conditions. The filling coefficient and grouting pressure were both within a reasonable range, ultimately resulting in dense backfilling and minimal surface settlement. In contrast, Comparative Example 1, using a fixed mix ratio and fixed grouting volume, experienced severe grout loss under conditions of increased torque and fractured surrounding rock, leading to incomplete filling and excessive surface settlement. This demonstrates that dynamically adjusting grouting parameters based on real-time conditions can effectively improve the quality of synchronous grouting behind the tunnel lining segments of a double-shield TBM. Even increasing the fixed grouting volume of Comparative Example 1 to 0.375m... 3 Because its gelling time is fixed at 65 minutes, a large amount of grout will still be lost in the fractured surrounding rock section, making it difficult to form effective support before the segments detach from the shield tail. This means that the problems of voids behind the wall and ground settlement cannot be fundamentally solved. This further confirms that the coordinated control of dynamic gelling time and dynamic grouting volume in real-time matching with the working conditions is the key to achieving reliable filling. Simply adjusting the injection volume cannot compensate for the filling quality defects caused by the mismatch of gelling time.

[0045] In another embodiment, in the synchronous grouting method behind the segment wall for a dual-shield TBM, during the tunneling process of the dual-shield TBM, the displacement of the segment that has detached from the shield tail is detected in real time. When the displacement is settlement and the settlement exceeds a preset settlement threshold, the target volume ratio corresponding to the current working condition combination in the initial volume ratio mapping table is reduced by a preset correction step size to obtain the corrected target volume ratio. The corrected target volume ratio is then used to replace the original target volume ratio of the working condition combination in the initial volume ratio mapping table. When the displacement is an upward float and the upward float exceeds the preset upward float threshold, the target volume ratio corresponding to the current working condition combination in the initial volume ratio mapping table is increased by the preset correction step size to obtain the corrected target volume ratio, and the original target volume ratio of the working condition combination in the initial volume ratio mapping table is replaced with the corrected target volume ratio. The preset correction step size ranges from 0.5 to 2.0.

[0046] During synchronous grouting behind the tunnel lining segments in a dual-shield TBM, even with dynamic adjustments to the volume ratio of liquid A to liquid B based on cutterhead torque and tunneling speed to control grout setting time, the stability of the segments after exiting the shield tail can still be affected by factors such as changes in surrounding rock conditions, uneven grout buoyancy distribution, or formation stress release. If the grout setting time is too long relative to the surrounding rock convergence rate, the buoyancy generated by the unsolidified grout may cause localized segment uplift; if the setting time is too short while surrounding rock deformation continues, the grout will lose its fluidity prematurely and will be unable to effectively transmit formation pressure, potentially causing segment settlement. Simply relying on a preset volume ratio mapping table for tunneling parameters lacks closed-loop feedback on the actual effects after grouting and cannot proactively correct for segment displacement deviations.

[0047] To address the aforementioned issues, the displacement of the tunnel segments that have exited the shield tail is monitored in real time during tunneling. Displacement refers to the vertical offset of the segment relative to its theoretical design axis, which can be continuously monitored using a static level or total station prism array installed on the inner wall of the segment. Preset settlement and upward displacement thresholds serve as boundary values ​​for determining whether the displacement exceeds limits. Their specific values ​​should be determined comprehensively based on the tunnel depth, surrounding rock grade, and protection requirements for surface structures. For example, in urban subway sections, the preset settlement threshold can be set to 5mm, and the preset upward displacement threshold can be set to 10mm. When the detected displacement is settlement and exceeds the preset settlement threshold, it indicates that the current grout gelation time is relatively long, and the grout has not fully solidified and can no longer restrain the segment's sinking trend. In this case, the target volume ratio corresponding to the current working condition combination in the initial volume ratio mapping table is reduced by a preset correction step. Reducing the volume ratio means decreasing the proportion of liquid A to liquid B, which shortens the gelation time of the mixed grout, accelerates the rate of grout strength growth, and thus provides vertical support reaction force to the segments earlier, inhibiting further settlement. Conversely, when the displacement is upward and the upward movement exceeds the preset upward threshold, it indicates that the current grout gelation time is relatively short. The grout thickens rapidly after injection into the gap and concentrates the buoyancy effect at the bottom of the segment. At this time, the target volume ratio corresponding to the current working condition combination in the initial volume ratio mapping table is increased by the preset correction step. Increasing the volume ratio prolongs the gelation time, allowing the grout more time to flow and distribute evenly within the annular gap, reducing the degree of local buoyancy concentration, and alleviating the upward trend of the segments. The preset correction step range is 0.5-2.0. If the value is too small, the correction effect is not obvious, and the displacement deviation needs to be accumulated through multiple loops to be corrected; if the value is too large, it is easy to cause a sudden change in the gelation characteristics of the grout, resulting in fluctuations in grouting pressure or discontinuous filling. Taking a preset correction step size of 1.0 as an example, if the target volume ratio under the current working condition is 3.2 to 1, it will be corrected to 2.2 to 1 when the settlement exceeds the limit, and to 4.2 to 1 when the floating exceeds the limit.

[0048] When the settlement of the tunnel lining segments exceeds the limit, it means that the uncured grout below or around the segments cannot provide sufficient supporting reaction force. At this time, shortening the grout setting time may slightly reduce the final diffusion range of the grout, but it can enable it to quickly form a strong framework in a short time, promptly stop the further development of settlement, and prevent segment misalignment and excessive deformation of the strata. This is the priority control target under the current working conditions.

[0049] It should be noted that before triggering the volume ratio increase correction based on the segment float, the control system first determines whether the grouting pressure is within the normal range (i.e., 1.05-1.15 times the soil and water pressure of the surrounding rock at the grouting point) and whether the grouting volume per unit time matches the theoretical calculation value. If the grouting pressure or grouting volume is significantly higher, the floatation is suppressed by reducing the grouting volume or adjusting the grouting pressure, rather than directly increasing the volume ratio. Only when both the grouting pressure and grouting volume are within the normal range but the floatation still exceeds the limit is it determined that the buoyancy concentration is caused by a short gelation time, and at this time, the volume ratio increase correction is executed. This dual verification mechanism can effectively avoid reverse correction caused by misjudgment.

[0050] The revised target volume ratio replaces the original target volume ratio for this working condition combination in the initial volume ratio mapping table, allowing the updated value to be directly used when tunneling reaches similar torque and speed ranges. This closed-loop adjustment mechanism feeds back the segment attitude monitoring results to the grouting parameter setting stage, ensuring that the mix ratio selection is based not only on the feedforward prediction of tunneling parameters but also on the feedback correction of the actual deformation response of the constructed sections. As the tunneling mileage increases, the mapping table values ​​gradually approach the optimal mix ratio for each working condition under the current geological conditions, improving the grouting system's adaptability to uncertainties in the surrounding rock. Using this method, the displacement development of segments in the initial stage of shield tail release is effectively suppressed, reducing secondary problems such as segment misalignment, joint leakage, and excessive tunnel axis deviation caused by excessive segment floating or settlement. It also creates conditions for subsequent secondary grouting correction without frequent shutdowns.

[0051] In another embodiment, in the synchronous grouting method behind the segment wall for a dual-shield TBM, the materials of liquid A include cement and water, and liquid B is a water glass solution, the parameters of which include modulus and Baumé degree. The volume ratio-gelling time relationship curve was established through the following steps: In the indoor test, the type and grade of cement in liquid A and the water-cement ratio of cement paste were fixed, and the modulus and Baumé degree of water glass in liquid B were fixed. Multiple sets of different volume ratios of liquid A to liquid B were set up, and the gelation time corresponding to each volume ratio was determined by the inverted cup method. Plot the volume ratio as the x-axis and the gelation time as the y-axis, and draw a scatter plot of the data of each group of volume ratios and gelation times. Then, obtain the corresponding curve of volume ratio-gelation time by curve fitting.

[0052] In the aforementioned method of dynamically adjusting the volume ratio of liquid A to liquid B based on cutterhead torque and tunneling speed, the volume ratio-gelling time correlation curve is the key basis for retrieving the target volume ratio from the target gelling time. Without an accurate correlation curve specific to the material formulation, directly referencing general data or empirical values ​​may lead to deviations between the calculated target volume ratio and the actual required ratio, thus affecting the accuracy of gelling time control. Different engineering projects may use different types and grades of cement, water-cement ratios, and the modulus and Baumé degree of water glass, all of which significantly affect the gelling reaction rate of the two-liquid slurry. For example, ordinary Portland cement and slag Portland cement have different reactivity with water glass due to their different mineral compositions; a higher water-cement ratio increases the spacing between cement particles, potentially changing the amount of water glass required to achieve the same gelling state; the water glass modulus, i.e., the molar ratio of silica to sodium oxide, indicates a higher degree of silicate polymerization and a faster gelling rate; and the Baumé degree reflects the concentration of the water glass solution, with higher concentrations resulting in more effective components participating in the reaction. Therefore, establishing a specific volume ratio-gelling time correspondence curve for each specific construction condition is a necessary prerequisite for ensuring the accuracy and reliability of the mix proportion mapping table.

[0053] To address the aforementioned issues, a volume ratio-cementation time correlation curve was established through indoor tests before the double-shield TBM tunneling. First, the type and grade of cement in solution A, as well as the water-cement ratio of the cement slurry, were fixed. Simultaneously, the modulus and Baume degree of water glass in solution B were fixed to ensure that the materials used in the tests were completely consistent with the actual grouting materials. The type and grade of cement determine its mineral composition and fineness, directly affecting the hydration reaction rate and its compatibility with water glass. The water-cement ratio refers to the ratio of the mass of water to the mass of cement in solution A, with a commonly used range of 0.6-1.0; for example, 0.8 means 0.8 kg of water per kilogram of cement. The water glass modulus refers to the molar ratio of silica to sodium oxide in the water glass, with a commonly used range of 2.4-3.4; for example, 2.8. The Baume degree is a unit for measuring the density of a water glass solution, expressed in °Bé, with a commonly used range of 35-40 °Bé; for example, 35 °Bé. After fixing the above variables, multiple sets of different volume ratios of liquid A to liquid B were set. The volume ratio refers to the ratio of the volume of liquid A to the volume of liquid B. For example, five sets were set: 2:1, 3:1, 4:1, 5:1, and 6:1. For each volume ratio, the corresponding gelation time was determined using the inverted cup method. The inverted cup method is a simple indoor gelation time determination method. During operation, a quantitatively mixed slurry is injected into a standard container. The container is tilted every few seconds to observe the flow state of the slurry. The gelation time is recorded when the slurry loses its fluidity and the liquid surface no longer returns to horizontal when tilted. The volume ratios and their measured gelation times were plotted as a scatter plot with volume ratio on the x-axis and gelation time on the y-axis. A continuous and smooth volume ratio-gelation time curve was obtained through curve fitting. This curve typically shows a trend of increasing gelation time with increasing volume ratio, and within a certain range, it approximates a linear or power function relationship.

[0054] After inputting the volume ratio-gelling time correlation curve established through indoor tests into the control system of the dual-shield TBM, the target gelling time T calculated by the control system during tunneling will uniquely correspond to a target volume ratio on this curve, thus completing the precise conversion from time parameters to mix proportion parameters. This process avoids the problem of not updating due to changes in gelling characteristics caused by material batch differences or formula adjustments, ensuring that the mix proportion command matches the actual reaction law of the currently used slurry. Using a dedicated curve improves the accuracy of the target volume ratio back-check, reduces misjudgments of working conditions due to excessively long or short gelling times caused by curve deviations, and thus improves the consistency of backfill quality and construction controllability behind the tunnel lining segments.

[0055] In another embodiment, the synchronous grouting method behind the segment walls for a dual-shield TBM involves obtaining the surrounding rock integrity coefficient K through acoustic testing during the TBM excavation process. v ; When K v When the value is less than 0.20, the safety factor k is reduced by 0.30. When 0.20≤K v When the value is less than 0.40, the safety factor k is reduced by 0.15. When 0.40≤K v When the value is less than 0.60, the value of the safety factor k is not adjusted. When 0.60≤K v When the value is less than 0.80, the safety factor k is increased by 0.10. When K v When the value is ≥0.80, the safety factor k is increased by 0.20; The target gelling time T is recalculated based on the adjusted safety factor k, and the adjusted target gelling time T is input into the pre-established volume ratio-gelling time correspondence curve to obtain the corrected target volume ratio. The corrected target volume ratio is then used to update the target volume ratio corresponding to the current working condition combination in the initial volume ratio mapping table.

[0056] In the aforementioned method of dividing working conditions based on cutterhead torque and tunneling speed and setting a preset safety factor k, the safety factor k is determined solely based on the torque range: 0.8 for the first torque range, 0.6 for the second, and 0.4 for the third. This setting can meet grouting requirements under conditions of good surrounding rock integrity. However, when a tunnel actually traverses strata, the degree of joint and fracture development in the surrounding rock varies significantly. Even within the same torque range, differences in surrounding rock integrity can lead to variations in grout loss and the self-stabilizing capacity of the surrounding rock. If the additional impact of surrounding rock integrity on grout setting time is not considered, the value of the safety factor k may deviate from the actual requirements, thus affecting the accuracy of the target setting time calculation.

[0057] To address the aforementioned issues, the rock integrity coefficient K was obtained through acoustic testing during the dual-shield TBM tunneling process. v Specifically, acoustic wave transmitting and receiving devices installed on the shield can be used to transmit acoustic signals to the surrounding rock adjacent to the shield and receive penetrating or reflected wave signals; alternatively, auxiliary openings on the tunnel segments can be used to conduct tests immediately after the segments exit the shield tail, thereby characterizing the integrity of the strata ahead of the current cycle and guiding the correction of the k-value for the next cycle. The surrounding rock integrity coefficient K... v This is a dimensionless parameter calculated by the square of the ratio of the longitudinal wave velocity of the rock mass to the longitudinal wave velocity of the rock sample. Its value ranges from 0 to 1; a higher value indicates a more intact rock mass and a lower degree of fracture development, while a lower value indicates a fragmented rock mass and well-developed fractures. When K... vWhen the value is less than 0.20, the surrounding rock is in a loose or extremely fractured structure, and the grout is severely lost along the fissures. In this case, the safety factor k is reduced by 0.30 from the original value in the torque range. For example, if the original value of k in the second torque range is 0.6, it is adjusted to 0.3 to shorten the target cementing time and reduce loss. When 0.20 ≤ K v When the value of the safety factor k is less than 0.40, the degree of rock fragmentation is relatively high, so the value of the safety factor k is reduced by 0.15. When 0.40 ≤ K v When the value is <0.60, the surrounding rock integrity is moderate, and the safety factor k is not adjusted, maintaining its original value corresponding to the torque range. When 0.60 ≤ K v When K < 0.80, the surrounding rock is relatively intact, and the risk of grout loss is reduced. However, excessively short cementation time may lead to insufficient filling. In this case, the safety factor k is increased by 0.10. When K v When the value is ≥0.80, the surrounding rock is extremely intact and dense. The safety factor k is increased by 0.20, and the cementation time is appropriately extended to ensure that the grout flows and fills the gaps sufficiently.

[0058] The adjusted safety factor k is used to recalculate the target gelation time T. The value of k in the calculation formula is replaced with the corrected value, while the other parameters L and v remain unchanged. The adjusted target gelation time T is input into a pre-established volume ratio-gelation time correspondence curve to obtain the corrected target volume ratio. This corrected value is then used to update the target volume ratio corresponding to the current working condition combination in the initial volume ratio mapping table. For example, K is obtained from a certain section of surrounding rock acoustic testing. v The value is 0.25. The current cutterhead torque is 1350 kN·m, which falls within the second torque range. The tunneling speed is 55 mm / min. The original safety factor k is taken as 0.6. Because K v The value is 0.25, which is in the range of 0.20 to 0.40. After the safety factor k is reduced by 0.15, it becomes 0.45. The shield tail length L is 4.2m. The target gelation time is recalculated and the volume ratio is checked. If the original target volume ratio is 3.2:1, it may be reduced to about 2.5:1 after correction. The gelation time of the slurry is shortened accordingly to meet the requirements of preventing loss under the condition of fractured surrounding rock.

[0059] By introducing the surrounding rock integrity coefficient K vA secondary correction to the safety factor k further incorporates information about the formation and rock mass quality into the grouting parameters, in addition to considering tunneling parameters. This method correlates the setting of the grout setting time with the actual degree of surrounding rock fragmentation. In fragmented sections, the setting time is shortened to suppress grout loss, while in intact sections, the setting time is appropriately extended to ensure uniform filling, compensating for the shortcomings of relying solely on torque range division. After implementation, the backfilling rate of grouting in different surrounding rock integrity sections tends to be balanced, voids caused by grout loss are significantly reduced, and the dispersion of segment floating or settling is reduced, improving the adaptability of double-shield TBM construction to complex geological conditions. In other words, the initial value of k is determined by the cutterhead torque range, which constitutes a rapid and rough assessment of the degree of surrounding rock fragmentation; furthermore, the acoustic integrity coefficient K... v This provides a quantitative basis for secondary correction of the initial value. The final safety factor obtained by combining the two can simultaneously reflect the difficulty of tunneling and the integrity of the rock mass itself, thus allowing for a more precise setting of the target cementing time.

[0060] In another embodiment, the synchronous grouting method behind the segment wall for a dual-shield TBM involves obtaining the groundwater erosivity level at the current tunneling location in real time during the tunneling process of the dual-shield TBM. When the groundwater corrosivity level is slightly corrosive, the Baumé degree of the water glass solution is increased by 0-1°Bé from the original Baumé degree. When the groundwater corrosivity level is weak, the Baumé degree of the water glass solution is increased by 1-3°Bé from the original Baumé degree. When the groundwater corrosivity level is moderate, the Baumé degree of the water glass solution should be increased by 3-5°Bé from the original Baumé degree. When the groundwater corrosivity level is strong, the Baumé degree of the water glass solution is increased by 5-8°Bé from the original Baumé degree. After adjusting the Baumé degree, the modulus of the water glass solution remains unchanged. The adjusted water glass solution is used as solution B, mixed with solution A, and then injected into the annular gap. Increasing the Baumé degree will correspondingly shorten the gelation time of the two-liquid slurry, but the extent of this shortening is very limited for the control system based on nine operating conditions and the target volume ratio. This system can automatically compensate for this slight deviation through real-time density detection and volume ratio feedback correction, ensuring that the actual gelation time remains within the effective range of the target operating condition. Therefore, there is no need to adjust the volume ratio-gelation time mapping relationship additionally.

[0061] Furthermore, when the Baume degree increases significantly (e.g., exceeding 5°Bé), a short-term test injection should be conducted before formal grouting to verify the delivery capacity of the B-liquid grouting pump and the mixing uniformity within the mixer. Continuous grouting can only proceed after confirming that there is no abnormal increase in pipeline pressure or a risk of localized gel blockage. If an abnormal increase in grouting pressure or increased pipeline vibration is observed during the test injection, the Baume degree adjustment range should be appropriately reduced, or additional pipeline insulation / cooling measures should be implemented to control the grout reaction rate.

[0062] In the aforementioned method of dynamically adjusting the volume ratio of liquid A to liquid B based on cutterhead torque and tunneling speed for simultaneous backfilling, the grouting material ratio is mainly determined by the compatibility of the grout setting time with the construction conditions, without specifically considering the impact of the groundwater chemical environment on the long-term durability of the grouted stone body. When the tunnel passes through groundwater areas containing corrosive ions, sulfate ions, chloride ions, or acidic groundwater may cause dissolution or swelling damage to the cement-based grouted stone body, leading to a decrease in strength and an increase in permeability after grout solidification, thereby weakening the supporting effect and water-proofing effect of the backfill layer on the tunnel segments. If the Baumé degree of the water glass solution in liquid B remains unchanged, the erosion resistance of the grouted stone body is difficult to adapt to the actual degree of groundwater erosion, which may result in insufficient local durability or waste of material properties.

[0063] To address the aforementioned issues, the groundwater corrosivity level at the current tunneling location is acquired in real time during the dual-shield TBM excavation process. The groundwater corrosivity level is classified according to the environmental water corrosivity evaluation standards for concrete, typically based on a comprehensive assessment of indicators such as sulfate ion content, magnesium ion content, pH value, and total mineralization, and is categorized into four levels: slight corrosivity, weak corrosivity, moderate corrosivity, and strong corrosivity. When the groundwater corrosivity level is slight, the Baumé degree of the water glass solution is increased by 0-1°Bé from the original Baumé degree. Baumé degree is a unit for measuring the concentration of water glass solution; a higher Baumé degree indicates a higher sodium silicate content and a more viscous solution. This slight increase in Baumé degree slightly increases the silica gel content in the grout aggregate, filling the micropores in the cement hydration products and slightly improving impermeability to cope with even very minor environmental erosion. When the groundwater erosion level is weak, the Baumé degree of the water glass solution is increased by 1-3°Bé from the original Baumé degree, for example, from 35°Bé to 36-38°Bé. Increasing the Baumé degree results in a denser silica gel network formed by the mixing reaction, which can, to some extent, hinder the penetration and migration of corrosive ions. When the groundwater erosion level is moderate, the Baumé degree of the water glass solution is increased by 3-5°Bé from the original Baumé degree. This significant increase in water glass concentration leads to a denser composite structure of gel and cement hydration products in the grout, effectively extending the path and time for the corrosive medium to reach the surface of the pipe segments. When the groundwater erosion level is strong, the Baumé degree of the water glass solution is increased by 5-8°Bé from the original Baumé degree, giving the grout higher resistance to chemical corrosion after solidification, maintaining long-term stability and bearing capacity in highly corrosive groundwater environments. During the Baumé degree adjustment process, the modulus of the water glass solution remains unchanged. The modulus of water glass refers to the molar ratio of silica to sodium oxide. The modulus determines the molecular structure and reactivity of water glass. Keeping the modulus constant means changing only the solution concentration without changing its chemical composition ratio, ensuring that the basic characteristics of the slurry gelation reaction do not fundamentally deviate after adjustment.

[0064] The water glass solution with adjusted Baume degree, designated as solution B, is mixed with solution A and injected into the annular gap between the outer wall of the tunnel segment and the surrounding rock through the grouting pipeline. Since the gelation time of the water glass with adjusted Baume degree may vary slightly from the original formula, the control system in actual construction still adjusts the ratio of solution A to solution B based on the target volume ratio. Changes in Baume degree are incorporated into the establishment of the volume ratio-gelation time curve during the grout performance testing phase, thus maintaining the accuracy of the mix proportion control. By adjusting the Baume degree of the water glass according to the groundwater corrosivity level, the durability of the grouting aggregate behind the tunnel wall adapts to the actual corrosion risk in different corrosive groundwater environments. This avoids later leakage and structural deterioration caused by insufficient grout durability in highly corrosive sections, and also avoids increased material costs and pumping difficulties due to excessive grout viscosity in slightly corrosive sections. This measure enables the grouting behind the tunnel wall of the double-shield TBM segment to adapt to construction conditions while ensuring the long-term operational safety of the tunnel.

[0065] In another embodiment, the synchronous grouting method behind the segment walls for a dual-shield TBM involves obtaining the surrounding rock integrity coefficient K through acoustic testing during the TBM excavation process. v ; When K v When <0.20, the filling coefficient should be 1.6-1.8; When 0.20≤K v When <0.40, the filling coefficient should be 1.5-1.7; When 0.40≤K v When <0.60, the filling coefficient should be 1.3-1.5; When 0.60≤K v When <0.80, the filling coefficient should be 1.2-1.3; When K v When the value is ≥0.80, the filling coefficient is taken as 1.2.

[0066] In the aforementioned method of calculating the theoretical volume of the annular gap based on the real-time tunneling speed and multiplying it by the filling coefficient to determine the grouting volume, the filling coefficient is taken as a fixed range of 1.2-1.8, and a certain value is selected based on experience during construction and then not adjusted. However, when a double-shield TBM traverses sections with different rock integrity, the degree of over-excavation, the density of fracture development, and the opening of the surrounding rock vary significantly, causing the deviation between the actual annular gap volume and the theoretical calculation value to change accordingly. In tunnel sections with good rock integrity, the over-excavation is small and there are few fractures, and the grout mainly fills the designed gap between the tunnel segments and the tunnel wall, with the actual required grout volume close to the theoretical value. In tunnel sections with poor or broken rock integrity, the over-excavation is severe and fractures are developed, and a large amount of grout will seep into the deep part of the surrounding rock along the fractures or accumulate in the over-excavated cavities, with the actual required grout volume being much greater than the theoretical value. If the same filling coefficient is used throughout the entire section, it may lead to excessive grouting, excessive pressure, or even grout entering the shield tail sealing system when the integrity is good, while insufficient injection volume may cause filling voids and potential instability of the surrounding rock when the integrity is poor.

[0067] To address the aforementioned issues, the rock integrity coefficient K was obtained through acoustic testing during the dual-shield TBM tunneling process. v Rock integrity coefficient K v This is a dimensionless parameter calculated by the square of the ratio of the longitudinal wave velocity of the rock mass to the longitudinal wave velocity of a fresh rock sample of the same lithology. Its value ranges from 0 to 1; a smaller value indicates a more fractured rock mass and more developed fissures. When K... v When K < 0.20, the surrounding rock exhibits a loose or extremely fragmented structure, with significant over-excavation and good fissure connectivity, resulting in multiple grout loss paths. The filling coefficient is taken as 1.6-1.8, meaning the actual grouting volume is 1.6-1.8 times the theoretical volume to compensate for substantial loss. When 0.20 ≤ K v When K < 0.40, the surrounding rock is highly fractured with dense joints and fissures, and the filling coefficient is taken as 1.5-1.7. When 0.40 ≤ K v When K < 0.60, the surrounding rock integrity is moderate, and the filling coefficient is taken as 1.3-1.5. When 0.60 ≤ K v When K < 0.80, the surrounding rock is relatively intact, with mild over-excavation and fracture development, and the filling coefficient is taken as 1.2-1.3. v When the density is ≥0.80, the surrounding rock is extremely intact and dense, the over-excavation is very small and the cracks are closed, the grout loss is negligible, the filling coefficient is taken as 1.2, and the grouting volume only needs to be slightly larger than the theoretical volume to compensate for the roughness of the segment wall and a small amount of construction loss. For example, a certain section of surrounding rock was tested by acoustic wave measurement K... v The value is 0.28, which falls under the condition 0.20 ≤ K. v For the range <0.40, the filling coefficient should be selected from 1.5 to 1.7. The specific value can be further fine-tuned based on the actual degree of fragmentation of the surrounding rock revealed in that section, such as taking 1.6. Correspondingly, in K... vFor a relatively intact surrounding rock section with a strength of 0.75, the filling coefficient only needs to be between 1.2 and 1.3, such as 1.25.

[0068] Based on the surrounding rock integrity coefficient K v By adjusting the filling coefficient in stages, the injection volume of the two-component grout per unit time can be more accurately matched with the actual grout volume that the surrounding rock can accommodate. Increasing the filling coefficient in fractured rock sections can effectively avoid backfill voids and continuous deformation of the surrounding rock caused by insufficient injection volume; while decreasing the filling coefficient in intact rock sections can prevent segment floating, grout waste, and runaway grouting pressure caused by excessive grouting. This measure transforms grout volume control from relying on a single empirical value to dynamic adjustment based on rock mass quality, improving the utilization rate of grouting materials and the compactness and uniformity of backfill, which is beneficial for the safe and efficient tunneling of double-shield TBMs under complex geological conditions.

[0069] In another embodiment, in the synchronous grouting method behind the segment wall for a double-shield TBM, a density detection unit is installed on the grouting pipeline during the tunneling process of the double-shield TBM, and the density of the mixed two-liquid grout is detected in real time by the density detection unit. Before the double-shield TBM tunneling, a density-volume ratio relationship curve was pre-established through indoor tests. The establishment method was as follows: The type and grade of cement in liquid A and the water-cement ratio of cement paste are fixed, and the modulus and Baumé degree of water glass in liquid B are fixed. Set up multiple sets of different volume ratios of liquid A to liquid B, and measure the density of the mixed two-liquid slurry corresponding to each volume ratio; Plot the volume ratio as the x-axis and the density as the y-axis, and draw a scatter plot of the volume ratio and density data for each group. Obtain the density-volume ratio relationship curve through curve fitting. During the tunneling process of the dual-shield TBM, the real-time detected density is converted into the actual volume ratio through the density-volume ratio correspondence curve; When the actual volume ratio is greater than the target volume ratio and the deviation exceeds the preset deviation threshold, reduce the output flow rate of the A liquid grouting pump or increase the output flow rate of the B liquid grouting pump until the deviation between the actual volume ratio and the target volume ratio is less than or equal to the preset deviation threshold. When the actual volume ratio is less than the target volume ratio and the deviation exceeds the preset deviation threshold, increase the output flow rate of the A liquid grouting pump or decrease the output flow rate of the B liquid grouting pump until the deviation between the actual volume ratio and the target volume ratio is less than or equal to the preset deviation threshold. The output flow rate of the grouting pump can be adjusted by using a frequency converter to adjust the motor speed, a speed control valve to adjust the hydraulic oil flow rate, or a PLC controller to adjust the stroke length. The adjustment range in a single instance shall not exceed ±5% of the current output flow rate of the grouting pump. The preset deviation threshold is ±0.2 to ±0.5 of the target volume ratio.

[0070] In the aforementioned method of determining the working condition combination based on real-time detection of cutterhead torque and tunneling speed and controlling the mixing ratio of liquid A and liquid B by retrieving the target volume ratio, the achievement of the target volume ratio depends on the A-liquid grouting pump and the B-liquid grouting pump outputting corresponding flow rates according to the set ratio. However, in actual construction, factors such as mechanical wear of the grouting pump, fluctuations in pipeline resistance, voltage changes, or local blockage of the grout suction port may cause the actual output flow rate ratio of liquid A and liquid B to deviate from the set value of the control system. If this deviation is not detected and corrected in time, the actual volume ratio of the two-liquid grout injected into the annular gap will differ from the target volume ratio, thereby causing the actual gelation time of the grout to deviate from the calculated target value, affecting the backfilling quality. Simply relying on open-loop control of the grouting pump speed or stroke lacks online feedback on the actual state of the mixed grout, making it difficult to guarantee the accuracy of the mixing ratio.

[0071] To address the aforementioned issues, a density detection unit is installed on the grouting pipeline during the dual-shield TBM tunneling process. This unit monitors the density of the mixed two-component grout in real time. The density detection unit can employ industrial online measuring instruments such as Coriolis mass flow meters, nuclear radiation densitometers, or differential pressure densitometers, and its output signal is transmitted to the control system. Because there is a significant density difference between the cement-based grout (component A) and the water glass solution (component B), the density of component A is typically 1.6-1.9 g / cm³. 3 The density of solution B is typically 1.3-1.4 g / cm³. 3 The density of a two-component slurry obtained by mixing the two components at different volume ratios changes systematically with the volume ratio. Before tunneling with a dual-shield TBM, a density-volume ratio correlation curve was pre-established through laboratory tests. The method was as follows: the type and grade of cement in component A and the water-cement ratio of the cement slurry were fixed, and the modulus and Baumé degree of water glass in component B were fixed; multiple sets of different volume ratios of component A and component B were set, for example, 2:1, 3:1, 4:1, 5:1, and 6:1; the density of the mixed two-component slurry corresponding to each volume ratio was measured; the data of each set were plotted as a scatter plot with volume ratio as the abscissa and density as the ordinate, and the density-volume ratio correlation curve was obtained by curve fitting. This curve has a one-to-one correspondence under the condition of fixed experimental material ratios, and the curve shape is usually monotonically increasing or monotonically decreasing, depending on the relative densities of component A and component B.

[0072] During the tunneling process of a dual-shield TBM, the density value of the mixed two-component slurry, detected in real time by the density detection unit, is input into the control system. This density is then converted into the actual volume ratio using a pre-stored density-volume ratio curve. The control system compares this actual volume ratio with the target volume ratio corresponding to the current working condition. A preset deviation threshold is set to ±0.2 to ±0.5 of the target volume ratio. For example, when the target volume ratio is 3.2:1, the allowable actual volume ratio range is 2.7:1 to 3.7:1 with a deviation threshold of ±0.5, or 3.0:1 to 3.4:1 with a deviation threshold of ±0.2. When the actual volume ratio is greater than the target volume ratio and the deviation exceeds the preset deviation threshold, it indicates that the proportion of liquid A is too high and the proportion of liquid B is too low. In this case, the output flow rate of the liquid A grouting pump is reduced or the output flow rate of the liquid B grouting pump is increased until the deviation between the actual volume ratio and the target volume ratio is less than or equal to the preset deviation threshold. When the actual volume ratio is less than the target volume ratio and the deviation exceeds the preset deviation threshold, it indicates that the proportion of liquid A is too low and the proportion of liquid B is too high. In this case, increase the output flow rate of the liquid A grouting pump or decrease the output flow rate of the liquid B grouting pump until the deviation between the actual volume ratio and the target volume ratio returns to within the allowable range. The output flow rate of the grouting pump is adjusted by using a frequency converter to regulate the motor speed, a speed control valve to regulate the hydraulic oil flow rate, or a PLC controller to regulate the stroke length. The adjustment range for each instance should not exceed ±5% of the current grouting pump output flow rate to avoid sudden changes in flow causing drastic fluctuations in grouting pressure or water hammer in the pipeline. For example, if the current output flow rate of the liquid A grouting pump is 40 L / min, the adjustment range for each instance should not exceed 2 L / min. The next adjustment should only be made after the density feedback stabilizes.

[0073] By using online density detection and feedback adjustment, the actual injected two-component grout volume ratio can track the target volume ratio set value in real time, overcoming the proportioning deviation caused by pumping system disturbances under open-loop control. This method extends the grout quality parameters from "preset instructions" to "online verification and correction," enabling the grouting control system to have self-correcting capabilities, significantly improving the accuracy and robustness of volume ratio control, thereby ensuring the reliable realization of the gelation time under actual construction conditions, and further enhancing the stability and consistency of grouting quality behind the tunnel lining segments.

[0074] In another embodiment, the synchronous grouting method behind the segment wall for a dual-shield TBM involves real-time monitoring of the grouting pressure during the tunneling process of the dual-shield TBM. When the grouting pressure is greater than 1.15-1.30 times the water and soil pressure of the surrounding rock at the grouting point, an alarm signal is issued, but the delivery of liquid A and liquid B is not stopped. When the grouting pressure is greater than or equal to 1.30 times the water and soil pressure of the surrounding rock at the grouting point, the delivery of liquid A and liquid B shall be stopped immediately and an alarm signal shall be issued.

[0075] In the aforementioned method of calculating the injection volume based on the real-time tunneling speed and maintaining the grouting pressure at 1.05-1.15 times the water and soil pressure of the surrounding rock at the grouting point, the control objective of the grouting pressure is to ensure that the grout smoothly fills the annular gap under reasonable resistance. However, in actual construction, various sudden situations may occur that lead to abnormal increases in grouting pressure. For example, the grouting pipeline may be partially blocked due to local solidification of the grout or the entry of foreign objects; local collapse of the surrounding rock near the grouting holes of the segments may narrow the grout outlet channel; or the filling coefficient may be set too high, causing the injection volume per unit time to exceed the gap's capacity. In the above situations, if only the conventional pressure regulation function of the grouting pump is relied upon without a targeted overpressure grading response mechanism, the grouting pressure may rise sharply within seconds, exceeding the pressure resistance limit of the shield tail sealing system, causing the sealing grease to break down and mud and water to rush in, or generating concentrated thrust on the segments that have just exited the shield tail, leading to annular joint misalignment and failure of the waterstop strip. On the other hand, frequent shutdowns due to pressure fluctuations will disrupt the normal tunneling rhythm and increase the difficulty of process connection.

[0076] To address the aforementioned issues, grouting pressure is monitored in real-time during the dual-shield TBM tunneling process. Grouting pressure is acquired via diaphragm pressure transmitters or strain gauge pressure sensors installed in the grouting pipeline near the grouting holes of the tunnel segments, and the signal is continuously transmitted to the control system. When the grouting pressure exceeds 1.15 times but does not reach 1.30 times the soil and water pressure of the surrounding rock at the grouting point, the control system issues an alarm signal but does not stop the delivery of fluid A and fluid B. The soil and water pressure of the surrounding rock at the grouting point refers to the sum of the pore water pressure and the effective stress of the soil at the location of the annular gap behind the tunnel segment wall. It is typically estimated using the groundwater level depth and the unit weight of the surrounding rock from the geological survey report, but can also be acquired in real-time using earth pressure sensors on the shield during tunneling. For example, if the calculated soil and water pressure at a grouting point in a certain section is 0.2 MPa, an alarm will be triggered when the grouting pressure rises to the range of 0.23-0.26 MPa. Alarm signals can be delivered via audible and visual alarms, pop-up prompts on the operating interface, or information push notifications from a remote monitoring platform. These signals remind operators to pay attention to the rising pressure trend and check whether the tunneling parameters are abnormal or whether there are signs of bending or blockage in the pipeline. At this time, the A-liquid grouting pump and the B-liquid grouting pump continue to operate to ensure uninterrupted grout supply, so as to avoid grout backflow at the grouting hole or grout stagnation and solidification in the pipeline due to frequent start-stop operations.

[0077] When the grouting pressure continues to rise and reaches or exceeds 1.30 times the surrounding rock and soil pressure at the grouting point, the control system immediately stops the delivery of liquid A and liquid B and issues an alarm signal. Taking the aforementioned 0.2 MPa surrounding rock and soil pressure as an example, when the grouting pressure reaches or exceeds 0.26 MPa, the system executes an emergency shutdown command. Immediately stopping the delivery of liquid A and liquid B cuts off the source of continued pressure increase, preventing pressure from exceeding the shield tail seal's bearing capacity or causing damage to the segment structure. An alarm signal is simultaneously issued, prompting operators to check and clear the grouting pipeline, check the grouting holes for blockage, or reduce the current filling coefficient before restarting grouting. Pressure release after shutdown can be achieved by slowly opening the pressure relief valve or by allowing the grout gel to shrink naturally and reduce pressure before resuming grouting.

[0078] By setting two levels of grouting pressure monitoring thresholds, the simple pressure maintenance strategy is upgraded to a safety control closed loop with early warning and automatic protection functions. The first-level alarm threshold is in the range of 1.15-1.30 times the surrounding rock water and soil pressure, which provides operators with a buffer time to intervene and adjust during continuous grouting, reducing unnecessary pump shutdowns and ensuring the continuity of tunneling and grouting operations. The second-level shutdown threshold is set at 1.30 times the surrounding rock pressure, automatically cutting off the grout supply before the pressure reaches a critical value that may endanger the safety of equipment and structure, effectively preventing overpressure accidents. This method balances construction efficiency and risk control, making the pressure management of the synchronous grouting process behind the double-shield TBM wall more robust and reliable.

[0079] In another embodiment, the synchronous grouting method behind the segment wall for a dual-shield TBM involves real-time monitoring of grouting pressure and real-time tunneling speed during the tunneling process of the dual-shield TBM. When the grouting pressure rises by more than 0.10 MPa within 30 seconds and the real-time tunneling speed changes by less than 5% within the same time period, it is determined that there is a risk of blockage in the grouting pipeline and an alarm signal is issued.

[0080] In the aforementioned method of calculating the injection volume and controlling the grouting pressure based on real-time tunneling speed, fluctuations in grouting pressure due to changes in surrounding rock conditions, grout flow resistance, and injection rate are normal. However, when local blockage occurs within the grouting pipeline, such as premature gelation of liquid A and liquid B at pipeline bends or conical valves, foreign objects entering the pipeline, or segment grouting holes being blocked by gravel, the grouting pressure will continuously rise within a short period. If only the absolute pressure value is observed without considering the rate of change over time, normal pressure increases due to increased tunneling speed may be misjudged as blockages, or initial signs of blockage may be overlooked due to the natural pressure drop when tunneling speed decreases. Furthermore, relying solely on operators' visual observation of pressure gauge pointer fluctuations makes it difficult to capture short-term, small-amplitude abnormal changes, delaying pipeline clearing and leading to further blockages or even grouting interruption.

[0081] To address the aforementioned issues, the grouting pressure and real-time tunneling speed are monitored in real time during the dual-shield TBM tunneling process. The control system synchronously acquires and compares these two signals. When the grouting pressure rises by more than 0.10 MPa within a continuous 30-second period, and the real-time tunneling speed changes by less than 5% within the same time frame, the control system determines that there is a risk of blockage in the grouting pipeline and issues an alarm signal. The grouting pressure rise refers to the absolute value of the difference between the pressure value at the end of the 30-second time window and the pressure value at the beginning. For example, if the grouting pressure is 0.20 MPa at a certain moment, and rises to 0.32 MPa after 30 seconds, the rise is 0.12 MPa, exceeding the set threshold of 0.10 MPa. The real-time tunneling speed change refers to the difference between the maximum and minimum tunneling speed within the same 30-second period divided by the average tunneling speed during that period. If the average speed is 50 mm / min, a fluctuation range between 47.5 and 52.5 mm / min is considered a change of no more than 5%. If the tunneling speed fluctuates significantly during this period due to changes in the hardness of the surrounding rock, with a change exceeding 5%, the increase in grouting pressure may be due to a mismatch between the injection volume and the gap generation rate, rather than pipeline blockage. In this case, a blockage alarm will not be triggered.

[0082] The purpose of setting a continuous 30-second observation window is to filter out instantaneous pressure pulses caused by grouting pump piston stroke switching or the collapse of tiny air bubbles in the pipeline, thus avoiding false alarms that could interfere with normal construction. The 0.10 MPa rise threshold comprehensively considers the typical resistance characteristics of the dual-liquid grout pipeline and the normal operating pressure fluctuation range of the grouting system. A threshold that is too small will trigger frequent alarms due to normal pressure fluctuations, while a threshold that is too large will only detect pressure when blockage is already severe. The condition that the tunneling speed change is less than 5% ensures that the pressure rise occurs under stable tunneling conditions and a constant annular gap formation rate, eliminating interference from pressure changes caused by active adjustments to tunneling parameters. An alarm is only issued when both conditions are met simultaneously, significantly improving the accuracy of pipeline blockage risk assessment.

[0083] After an alarm signal is issued, operators can take measures before the blockage fully forms. These measures include briefly increasing the grouting pump output flow to attempt to clear minor blockages, tapping the pipeline to vibrate and dislodge any attached material, or switching to a backup grouting pipeline to continue grouting and cleaning the original pipeline during subsequent shutdowns. By adopting these monitoring and early warning methods, the number of forced shutdowns due to pipeline blockages is reduced, ensuring the continuity of grouting operations. Simultaneously, it avoids pipeline rupture or seal failure accidents caused by a sudden pressure surge after blockage, improving the operational reliability and construction safety of the dual-shield TBM synchronous grouting system.

[0084] In another embodiment, the method for synchronous grouting behind the segment walls of a dual-shield TBM includes cement, water, and bentonite in liquid A. The weight ratio of water to cement in liquid A is 0.8-1.2:1, and the bentonite accounts for 2%-6% of the weight of cement in liquid A. Solution B is a water glass solution with a modulus of 2.4-3.4 and a Baumé degree of 30-45°Bé.

[0085] Although the embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details.

Claims

1. A method for synchronous grouting behind the segment wall of a double-shield TBM, characterized in that, Includes the following steps: Inside the tail of the double-shield TBM, a dual-liquid grout is injected into the annular gap between the outer wall of the segment and the surrounding rock through pre-reserved grouting holes on the segment before the segment is assembled and before it detaches from the tail. The dual-liquid grout consists of liquid A and liquid B, where liquid A is a cement-based grout and liquid B is a water glass solution. After being mixed in a mixer via their respective delivery pipelines, liquids A and B are sent to the grouting holes through the grouting pipeline and injected into the annular gap. During the injection process, the grouting pressure is maintained at 1.05-1.15 times the water and soil pressure of the surrounding rock at the grouting point; Before tunneling with the dual-shield TBM, the cutterhead torque of the dual-shield TBM is divided into a first torque range, a second torque range, and a third torque range. The first torque range is ≤1000 kN·m, 1000 kN·m < the second torque range ≤1500 kN·m, and the third torque range >1500 kN·m. The tunneling speed of the dual-shield TBM is divided into a first tunneling speed range, a second tunneling speed range, and a third tunneling speed range. The first tunneling speed range is ≤40 mm / min, 40 mm / min < the second tunneling speed range ≤60 mm / min, and the third tunneling speed range >60 mm / min. The above three torque ranges and three tunneling speed ranges are combined in pairs to form nine working condition combinations. For each working condition combination, the target gelling time T is calculated using the formula T = k × L / v, where L is the shield tail length, v is the tunneling speed in the corresponding tunneling speed range, and k is the safety factor. When the working condition combination corresponds to the first torque range, k is 0.8; when it corresponds to the second torque range, k is 0.6; and when it corresponds to the third torque range, k is 0.

4. The target gelling time T is input into the pre-established volume ratio-gelling time correspondence curve, and the target volume ratio is obtained by reverse lookup. Thus, an initial volume ratio mapping table is established, which corresponds one-to-one with the nine working condition combinations and the nine target volume ratios, and is pre-stored in the control system of the dual-shield TBM. During the tunneling process of the dual-shield TBM, the cutterhead torque and the real-time tunneling speed are detected in real time to determine the working condition combination corresponding to the current torque range and tunneling speed range. The target volume ratio corresponding to the current working condition combination is retrieved from the initial volume ratio mapping table, and the mixing ratio of liquid A and liquid B is controlled according to the target volume ratio. The theoretical volume of the newly formed annular gap per unit time is calculated based on the real-time tunneling speed. The theoretical volume is then multiplied by the filling coefficient to obtain the injection volume of the two-liquid grout per unit time. The filling coefficient is 1.2-1.

8.

2. The method for synchronous grouting behind the segment wall of a double-shield TBM according to claim 1, characterized in that, During the tunneling process of the dual-shield TBM, the displacement of the segments that have detached from the shield tail is detected in real time. When the displacement is settlement and the settlement exceeds the preset settlement threshold, the target volume ratio corresponding to the current working condition combination in the initial volume ratio mapping table is reduced by a preset correction step size to obtain the corrected target volume ratio. The original target volume ratio of the working condition combination in the initial volume ratio mapping table is replaced by the corrected target volume ratio. When the displacement is an upward float and the upward float exceeds the preset upward float threshold, the target volume ratio corresponding to the current working condition combination in the initial volume ratio mapping table is increased by the preset correction step size to obtain the corrected target volume ratio, and the original target volume ratio of the working condition combination in the initial volume ratio mapping table is replaced with the corrected target volume ratio. The preset correction step size ranges from 0.5 to 2.

0.

3. The method for synchronous grouting behind the segment wall of a double-shield TBM according to claim 1, characterized in that, The materials of liquid A include cement and water, and liquid B is a water glass solution. The parameters of the water glass solution include modulus and Baumé degree. The volume ratio-gelling time relationship curve was established through the following steps: In the indoor test, the type and grade of cement in liquid A and the water-cement ratio of cement paste were fixed, and the modulus and Baumé degree of water glass in liquid B were fixed. Multiple sets of different volume ratios of liquid A to liquid B were set up, and the gelation time corresponding to each volume ratio was determined by the inverted cup method. Plot the volume ratio as the x-axis and the gelation time as the y-axis, and draw a scatter plot of the data of each group of volume ratios and gelation times. Then, obtain the corresponding curve of volume ratio-gelation time by curve fitting.

4. The method for synchronous grouting behind the segment wall of a double-shield TBM according to claim 1, characterized in that, During the tunneling process of a dual-shield TBM, the rock integrity coefficient K was obtained through acoustic testing. v ; When K v When the value is less than 0.20, the safety factor k is reduced by 0.

30. When 0.20≤K v When the value is less than 0.40, the safety factor k is reduced by 0.

15. When 0.40≤K v When the value is less than 0.60, the value of the safety factor k is not adjusted. When 0.60≤K v When the value is less than 0.80, the safety factor k is increased by 0.

10. When K v When the value is ≥0.80, the safety factor k is increased by 0.20; The target gelling time T is recalculated based on the adjusted safety factor k, and the adjusted target gelling time T is input into the pre-established volume ratio-gelling time correspondence curve to obtain the corrected target volume ratio. The corrected target volume ratio is then used to update the target volume ratio corresponding to the current working condition combination in the initial volume ratio mapping table.

5. The method for synchronous grouting behind the segment wall of a double-shield TBM according to claim 1, characterized in that, During the tunneling process of the dual-shield TBM, the groundwater erosion level at the current tunneling location is obtained in real time; When the groundwater corrosivity level is slightly corrosive, the Baumé degree of the water glass solution is increased by 0-1°Bé from the original Baumé degree. When the groundwater corrosivity level is weak, the Baumé degree of the water glass solution is increased by 1-3°Bé from the original Baumé degree. When the groundwater corrosivity level is moderate, the Baumé degree of the water glass solution should be increased by 3-5°Bé from the original Baumé degree. When the groundwater corrosivity level is strong, the Baumé degree of the water glass solution is increased by 5-8°Bé from the original Baumé degree. After adjusting the Baumé degree, the modulus of the water glass solution remains unchanged. The adjusted water glass solution is then used as solution B, mixed with solution A, and injected into the annular gap.

6. The method for synchronous grouting behind the segment wall of a double-shield TBM according to claim 1, characterized in that, During the tunneling process of a dual-shield TBM, the rock integrity coefficient K was obtained through acoustic testing. v ; When K v When <0.20, the filling coefficient should be 1.6-1.8; When 0.20≤K v When <0.40, the filling coefficient should be 1.5-1.7; When 0.40≤K v When <0.60, the filling coefficient should be 1.3-1.5; When 0.60≤K v When <0.80, the filling coefficient should be 1.2-1.3; When K v When the value is ≥0.80, the filling coefficient is taken as 1.

2.

7. The method for synchronous grouting behind the segment wall of a double-shield TBM according to claim 1, characterized in that, During the tunneling process of the dual-shield TBM, a density detection unit is installed on the grouting pipeline to detect the density of the mixed two-component grout in real time. Before the double-shield TBM tunneling, a density-volume ratio relationship curve was pre-established through indoor tests. The establishment method was as follows: The type and grade of cement in liquid A and the water-cement ratio of cement paste are fixed, and the modulus and Baumé degree of water glass in liquid B are fixed. Set up multiple sets of different volume ratios of liquid A to liquid B, and measure the density of the mixed two-liquid slurry corresponding to each volume ratio; Plot the volume ratio as the x-axis and the density as the y-axis, and draw a scatter plot of the volume ratio and density data for each group. Obtain the density-volume ratio relationship curve through curve fitting. During the tunneling process of the dual-shield TBM, the real-time detected density is converted into the actual volume ratio through the density-volume ratio correspondence curve; When the actual volume ratio is greater than the target volume ratio and the deviation exceeds the preset deviation threshold, reduce the output flow rate of the A liquid grouting pump or increase the output flow rate of the B liquid grouting pump until the deviation between the actual volume ratio and the target volume ratio is less than or equal to the preset deviation threshold. When the actual volume ratio is less than the target volume ratio and the deviation exceeds the preset deviation threshold, increase the output flow rate of the A liquid grouting pump or decrease the output flow rate of the B liquid grouting pump until the deviation between the actual volume ratio and the target volume ratio is less than or equal to the preset deviation threshold. The output flow rate of the grouting pump can be adjusted by using a frequency converter to adjust the motor speed, a speed control valve to adjust the hydraulic oil flow rate, or a PLC controller to adjust the stroke length. The adjustment range in a single instance shall not exceed ±5% of the current output flow rate of the grouting pump. The preset deviation threshold is ±0.2 to ±0.5 of the target volume ratio.

8. The method for synchronous grouting behind the segment wall of a double-shield TBM according to claim 1, characterized in that, During the tunneling process of the dual-shield TBM, the grouting pressure is monitored in real time; When the grouting pressure is greater than 1.15-1.30 times the water and soil pressure of the surrounding rock at the grouting point, an alarm signal is issued, but the delivery of liquid A and liquid B is not stopped. When the grouting pressure is greater than or equal to 1.30 times the water and soil pressure of the surrounding rock at the grouting point, the delivery of liquid A and liquid B shall be stopped immediately and an alarm signal shall be issued.

9. The method for synchronous grouting behind the segment wall of a double-shield TBM according to claim 1, characterized in that, During the tunneling process of the dual-shield TBM, the grouting pressure and the tunneling speed are monitored in real time. When the grouting pressure rises by more than 0.10 MPa within 30 seconds and the real-time tunneling speed changes by less than 5% within the same time period, it is determined that there is a risk of blockage in the grouting pipeline and an alarm signal is issued.

10. The method for synchronous grouting behind the segment wall of a double-shield TBM according to claim 3, characterized in that, Liquid A consists of cement, water, and bentonite. The weight ratio of water to cement in Liquid A is 0.8-1.2:1, and bentonite accounts for 2%-6% of the weight of cement in Liquid A. Solution B is a water glass solution with a modulus of 2.4-3.4 and a Baumé degree of 30-45°Bé.

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