Bad section TBM tunneling construction method

Abstract

The invention discloses a tunnel boring machine (TBM) tunneling construction method in a bad section, belongs to the technical field of building construction, and provides the following scheme aiming at the problems of insufficient geological detection precision, low data fusion efficiency, extensive grouting and drainage control and the like in the prior art. Recording the particle size distribution, the water content and the fracture development degree of the rock debris to mark a fracture zone, a water-rich zone and a weak intercalated layer; three groups of double-frequency geological radar probes are arranged at the tail part of the shield, data are collected and a dielectric constant difference value is calculated when the cutterhead is propelled by one meter, and when the difference value exceeds 15%, the propelling speed is automatically reduced and the cutterhead torque is limited; quick-setting cement-water glass double-liquid slurry is injected through a grouting hole in the top of the shield, and vacuum drainage and an annular water stop belt are used for a water-rich belt; an H-shaped steel arch frame is installed in the weak intercalated layer area, and settlement is monitored in real time. The method is suitable for tunnel construction under complex geological conditions, the surrounding rock reinforcing effect is optimized through multi-source data fusion and dynamic control, and the tunneling safety and efficiency are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of construction. More specifically, the present invention relates to a TBM tunneling construction method in poor ground conditions. Background Art

[0002] In the construction of tunnel boring machines (TBMs), the tunneling efficiency and safety in poor ground conditions face multiple technical challenges. The existing technologies have the following problems in the construction of areas with complex geological conditions: Traditional advanced drilling technologies mainly rely on the analysis of cuttings from a single borehole, and the discreteness of data collection is relatively large. For example, the particle size distribution of cuttings is usually completed by simple screening, and the statistics of coarse particles (such as particles with a diameter greater than 50 mm) lack systematicness, resulting in a large error in determining the boundary of the fracture zone. The measurement of moisture content and fracture density often lags behind the tunneling progress and is difficult to reflect the dynamic changes of geological conditions in a timely manner. The limitations of this data collection method make the adjustment of construction parameters (such as propulsion speed, torque limit) rely on manual experience, and misjudgment or response delay is likely to occur.

[0003] Ground penetrating radar detection often uses a single-frequency band antenna, making it difficult to balance high resolution in shallow layers and deep detection capabilities. For example, the 500 MHz frequency band is sensitive to the details of shallow rock masses but has a weak response to deep fracture zones; although the 800 MHz frequency band can detect deeper areas, it is easily interfered by the heterogeneity of the surrounding rock. In addition, the spatio-temporal matching of radar data and drilling data is insufficient, and there is a lack of effective fusion algorithms, resulting in a large deviation in the calculation of dielectric constant differences. This separate data processing method makes the adjustment of construction parameters lack a scientific basis and is difficult to adapt to the rapid changes in complex geological conditions.

[0004] In conventional grouting processes, the monitoring of slurry diffusion pressure mostly uses orifice point pressure gauges, which can only obtain local data and cannot grasp the three-dimensional distribution state of the slurry in the surrounding rock in real time. The setting of grouting pressure is often based on fixed empirical values and does not consider the proportional relationship between the length of the fracture zone and the diameter of the cutter head, resulting in insufficient grouting in short-distance fracture zones or slurry waste in long-distance sections. During the construction in water-rich zones, the negative pressure control of the vacuum pump lacks a dynamic adjustment mechanism, and sudden changes in the water inflow are likely to cause blockage of drainage holes or a decrease in drainage efficiency. The adaptability of the installation position of the water stop belt to the gap with the surrounding rock is insufficient, further exacerbating the leakage risk.

[0005] In the support of weak interlayer areas, steel arch frames with fixed spacing are mostly used, without dynamically adjusting in combination with the deformation rate of the surrounding rock. For example, the setting of the arch frame spacing does not consider the crack propagation rate, resulting in insufficient support strength or resource waste. Settlement monitoring relies on manual regular measurement of total station data, with a low monitoring frequency and it is difficult to capture local settlement mutations in a timely manner. The selection of grouting hole positions and the control of grouting volume for supplementary grouting lack data support, and the treatment effects vary.

[0006] In the prior art, various links such as geological exploration, grouting control, and support installation operate independently, resulting in broken data streams and an inability to form a closed-loop feedback. For example, after the identification of a broken zone, manual intervention is required to adjust the construction parameters, leading to a significant response delay. Especially in the area where the broken zone intersects with the water-rich zone, it is difficult to coordinate multiple processes, and it is hard to balance construction efficiency and safety. These problems stem from the fragmentation and static nature of technical means, resulting in insufficient dynamic adaptability between construction parameters and geological conditions. Summary of the Invention

[0007] An object of the present invention is to solve at least the above problems and provide at least the advantages described hereinafter.

[0008] To achieve these and other advantages in accordance with the present invention, a construction method for TBM tunneling in poor ground sections is provided, comprising the following steps: Implement advanced drilling within a range of 30 meters to 50 meters in front of the TBM cutterhead. Use a drill hole with a diameter of 100 millimeters. The drill holes are arranged circumferentially at an interval of 30 degrees along the tunnel axis, and the drill hole depth is 15 meters to 20 meters. During the drilling process, record the particle size distribution, moisture content, and degree of rock layer fracture development of the cuttings. Mark different geological sections according to the particle size distribution, moisture content, and degree of rock layer fracture development data of the cuttings obtained from the advanced drilling. The geological sections include broken zones, water-rich zones, and soft interlayers. Set three groups of retractable ground penetrating radar probes at the tail of the TBM shield. The three groups of probes are located at the 120-degree position at the top of the shield, the 240-degree position on the left, and the 0-degree position on the right. Each group of probes includes dual-frequency antennas with transmitting frequencies of 500 MHz and 800 MHz, and collect ground penetrating radar data once every 1 meter of cutterhead advancement. Input the advanced drilling data and the ground penetrating radar data into the computer control system. When the difference in dielectric constant between the broken zone and that shown by the ground penetrating radar exceeds 15%, automatically reduce the propulsion speed to 10 millimeters per minute to 15 millimeters per minute, and at the same time limit the cutterhead torque to 60% to 70% of the rated value. During the process of passing through the broken zone, inject quick-setting cement-sodium silicate double-fluid slurry through the grouting holes reserved at the top of the shield. Control the grouting pressure at 0.8 MPa to 1.2 MPa, the water-cement ratio at 0.6:1, and the sodium silicate content at 3% to 5% of the cement weight. The grouting range covers the section 3 meters to 5 meters behind the cutterhead. When tunneling to the water-rich zone, start the drainage holes at the center of the cutterhead. The diameter of the drainage holes is 200 millimeters. Maintain the negative pressure in the holes at -0.05 MPa to -0.08 MPa through a vacuum pump. At the same time, install a circumferential water stop at the outside of the shield. The water stop is made of ethylene propylene diene monomer rubber, with a cross-sectional width of 150 millimeters and a thickness of 12 millimeters. When tunneling in the area of the weak interlayer, a steel arch support is installed 2 meters behind the cutter head. The steel arch is made of H-shaped steel, with a cross-sectional height of 180 mm and a flange width of 90 mm. The spacing between adjacent arches is 0.8 m to 1.0 m. The arches are connected by threaded steel with a diameter of 22 mm, and the spacing of the longitudinal connecting bars is 1.5 m. After each cycle of tunneling is completed, settlement monitoring targets are installed at the invert of the tunnel. The spacing between the targets is 10 m. The total station is used to measure the three-dimensional coordinates of the targets in real time. When the settlement difference between adjacent targets exceeds 5 mm, supplementary grouting is carried out in the corresponding section. The depth of the grouting holes is 3 m to 4 m, and the grouting volume is 0.3 cubic meters to 0.5 cubic meters per linear meter.

[0009] The present invention combines advanced drilling and geological radar data to improve the identification accuracy of geological anomaly areas. By implementing multi-hole drilling in front of the cutter head and recording cuttings data, and combining with the three-dimensional data acquisition of the dual-frequency radar probe, the ranges of the broken zone, water-rich zone and weak interlayer can be accurately demarcated. The dynamic control of the grouting pressure and drainage negative pressure ensures the effectiveness of surrounding rock reinforcement and water inrush treatment. The linkage mechanism of the steel arch support and settlement monitoring improves the construction safety in the weak interlayer area and reduces the risk of collapse.

[0010] Preferably, marking different geological sections according to the particle size distribution, moisture content and fracture development degree data of the cuttings obtained from advanced drilling specifically includes: Mark the section where the proportion of particles with a particle size greater than 50 mm exceeds 30% as the broken zone, mark the section where the moisture content exceeds 25% as the water-rich zone, and mark the section where the fracture density exceeds 5 fractures per meter as the weak interlayer.

[0011] The present invention defines the classification criteria for geological sections through the quantitative thresholds of particle size proportion, moisture content and fracture density. When the proportion of particles with a particle size greater than 50 mm exceeds 30%, it is determined as the broken zone; when the moisture content exceeds 25%, it is determined as the water-rich zone; when the fracture density exceeds 5 fractures per meter, it is determined as the weak interlayer, reducing misjudgment caused by subjective experience. This classification method provides a unified basis for subsequent construction parameter adjustment, improving the standardization and operability of geological identification.

[0012] Preferably, input the advanced drilling data and geological radar data into the computer control system. When the difference in dielectric constant between the broken zone and that shown by the geological radar exceeds 15%, automatically reduce the propulsion speed to 10 mm / min to 15 mm / min, and at the same time limit the cutter head torque to 60% to 70% of the rated value. This step specifically includes: Obtain the first dielectric constant ε1 in the 500 MHz frequency band and the second dielectric constant ε2 in the 800 MHz frequency band respectively through the dual-frequency antenna of the geological radar; For the fractured zone area marked by advanced drilling, extract the average value of ε1 and the average value of ε2 within the detection range of ground penetrating radar in this area, and calculate the absolute differences Δε1 = |ε1 - ε0| and Δε2 = |ε2 - ε0| from the reference value ε0 of intact surrounding rock respectively; Perform weighted calculation on Δε1 and Δε2 with a weight coefficient of 0.6:0.4 to obtain the comprehensive dielectric constant difference Δε = 0.6Δε1 + 0.4Δε2; When Δε > 15%, the computer control system selects control parameters according to the numerical range of Δε: when 15% < Δε ≤ 25%, the propulsion speed is adjusted to 12 mm / min to 15 mm / min, and the cutter head torque is limited to 65% to 70% of the rated value; when Δε > 25%, the propulsion speed is adjusted to 10 mm / min to 12 mm / min, and the cutter head torque is limited to 60% to 65% of the rated value; When the cutter head advances 200 mm each time, collect ground penetrating radar data again to update the value of Δε, and dynamically adjust the propulsion speed and torque parameters.

[0013] The present invention adopts the weighted calculation and dynamic update mechanism of dual-frequency dielectric constant to improve the accuracy of fractured zone discrimination. Through the fusion of data in the 500 MHz and 800 MHz frequency bands, combined with the analysis of the difference from the reference value of intact surrounding rock, the quantitative evaluation of the change in dielectric characteristics is realized. According to the difference interval, the propulsion speed and torque parameters are adjusted in grades, so that the equipment load is dynamically adapted to the geological conditions, and the risk of cutter head overload is reduced.

[0014] Preferably, the marking method of the fractured zone includes: During the advanced drilling process, extract rock debris samples every 0.5 m of drilling, perform dry screening classification using standard square hole sieves with apertures of 100 mm, 50 mm, 20 mm, and 5 mm, weigh the weight of the coarse grain section with a particle size greater than 50 mm and calculate the proportion. When the proportion of the coarse grain section in three consecutive samples all exceeds 30%, it is determined as a fractured zone; According to the drill pipe inclination angle α and azimuth angle β, convert the starting point depth L of the fractured zone into the three-dimensional coordinates of the tunnel axis coordinate system. The conversion formula is x = L·sinα·cosβ, y = L·sinα·sinβ, z = L·cosα, and the coordinate positioning error is controlled within ±0.3 m; Drill verification holes in the fractured zone area and insert an endoscopic camera probe. When the observed fracture density is greater than 5 fractures / m and the aperture is greater than 3 mm, confirm the boundary range of the fractured zone.

[0015] The present invention achieves high-precision positioning of the broken zone through continuous rock cuttings sample screening and three-dimensional coordinate conversion. Samples are extracted every 0.5 meters and the proportion of coarse grains is calculated. The broken zone is determined when three consecutive samples exceed the threshold value to avoid single sample errors. Combined with the spatial coordinate mapping of the drill pipe inclination and azimuth, the positioning error is controlled within ±0.3 meters. The verification hole endoscopic camera directly observes the density and opening of the fracture, further confirms the boundary range, and improves the reliability of the marking.

[0016] Preferably, the complete surrounding rock reference value ε0 is obtained by the following steps: In the tunnel section at least 50 meters away from the fracture zone, the section with a core sampling rate greater than 90%, an RQD value greater than 85%, and no geological anomalies with a water content greater than 15% or a crack density greater than 1 / m is selected as the reference section; Geological radar measurement points are arranged at intervals of 5 meters along the axis of the tunnel in the reference section, and 10 sets of dielectric constant measurement data are collected in the 500 MHz frequency band and 10 sets of dielectric constant measurement data are collected in the 800 MHz frequency band using a dual-frequency antenna; The Grubbs criterion was used to eliminate outliers in each set of measurement data. When the measured value deviated from the mean value of the group by more than 3 standard deviations, the abnormal measured value was deleted. The arithmetic mean of the effective measurement data in the 500MHz frequency band is calculated as ε01, and the arithmetic mean of the effective measurement data in the 800MHz frequency band is calculated as ε02; ε01 and ε02 are synthesized at a weight ratio of 0.7:0.3, and the comprehensive benchmark value ε0=0.7×ε01+0.3×ε02 is calculated; After completing every 200 meters of tunnel excavation, the benchmark section selection and measurement steps are re-executed. When the newly obtained ε0 value deviates from the original value by more than 8%, the geological radar system calibration procedure is started and the geological conditions of the benchmark section are reviewed.

[0017] The present invention ensures the representativeness of the complete surrounding rock benchmark value by strictly screening the benchmark section and fusing the dual-frequency data. The section with the core recovery rate exceeding 90% and the RQD value exceeding 85% is selected to exclude the interference of geological anomalies. The dual-frequency data is weighted to synthesize the benchmark value, taking into account both high-frequency details and low-frequency penetration. The benchmark value is updated and calibrated every 200 meters to adapt to the gradual change of the surrounding rock, maintain the long-term validity of the data, and provide a stable basis for the calculation of the dielectric constant difference.

[0018] Preferably, the injection control of the quick-setting cement-water glass double slurry comprises the following steps: Distributed optical fiber pressure sensors are installed in the grouting holes, with a measuring point arranged every 0.5 meters along the hole depth to monitor the slurry diffusion pressure distribution in real time; Select the grouting mode according to the ratio of the length L of the marked area of the fracture zone to the cutter head diameter D: When L / D < 0.5, continuous grouting is adopted, and the grouting speed is maintained at 8 L / min to 10 L / min; when L / D ≥ 0.5, pulse grouting is adopted, and it alternates with a cycle of 30 seconds of grouting / 15 seconds of intermittent; The slurry ratio is closed-loop controlled by an electromagnetic flowmeter and a pressure transmitter on the grouting pipeline. When the real-time pressure exceeds the set pressure upper limit of 1.2 MPa, the sodium silicate dosage is automatically adjusted to the upper limit value of 5%. When the pressure is lower than 0.8 MPa, the water-cement ratio is synchronously reduced to 0.55:1; Arrange a borehole coring verification point 5 meters behind the cutter head, use a drill bit with a diameter of 100 mm to obtain the grouting body core sample. When the core sample strength is lower than 20 MPa or the permeability coefficient is greater than 1×10 -7 cm / s, inject additional sodium silicate strengthening slurry with a dosage of 7% at the adjacent grouting hole positions.

[0019] The present invention monitors the slurry diffusion in real time through a distributed optical fiber pressure sensor, improving the accuracy of grouting control. Select continuous or pulse grouting mode according to the ratio of the fracture zone length to the cutter head diameter to adapt to different geological scale requirements. Close-loop adjust the sodium silicate dosage and the water-cement ratio to maintain the stability of the slurry performance. Borehole coring verifies the strength and permeability coefficient of the grouting body, and inject additional strengthening slurry when it is lower than the threshold value to ensure that the surrounding rock reinforcement quality meets the standard.

[0020] Other advantages, objectives and features of the present invention will be partially reflected by the following description, and will also be understood by those skilled in the art through the research and practice of the present invention. Detailed implementation manners

[0021] The following further elaborates the present invention in detail with reference to embodiments, so that those skilled in the art can implement it according to the description in the specification.

[0022] The present invention provides a construction method for TBM tunneling in poor sections, including the following steps: Implement advanced drilling within the range of 30 meters to 50 meters in front of the TBM cutter head. Use a drill hole with a diameter of 100 mm. The drill holes are arranged circumferentially at an interval of 30 degrees along the tunnel axis, and the drill hole depth is 15 meters to 20 meters. Record the particle size distribution, moisture content of the cuttings and the development degree of rock fractures during the drilling process; Mark different geological sections according to the particle size distribution, moisture content of the cuttings and the data of the development degree of rock fractures obtained from the advanced drilling. The geological sections include fracture zones, water-rich zones and soft interlayers; Specifically, the drilling diameter can also be selected as 110 mm or 120 mm. The circumferential interval of the drilling can also be set to 45 degrees or 60 degrees. The drilling depth can be chosen as 15 m, 18 m or 20 m. The determination threshold for the broken zone can be set to 30% of the proportion of the coarse-grained section, the threshold for the water-rich zone is 25% water content, and the threshold for the weak interlayer is 5 fractures per meter of fracture density.

[0023] For the advance drilling, a hydraulic rotary drill can be selected, and the drill pipe material can be selected as high-strength alloy steel. For the cuttings screening, standard square-hole sieves can be selected, with pore diameters including 100 mm, 50 mm, 20 mm and 5 mm, and the material is stainless steel. For the data recording, a portable electronic balance can be selected, with a measuring range of 0 - 10 kg and an accuracy of ±1 g. For the fracture observation, an endoscope camera probe can be selected, with a resolution of 1920×1080 pixels.

[0024] The drill rig is assembled within the range of 30 m to 50 m in front of the TBM cutter head and fixed to the tunnel sidewall through a hydraulic support. A cuttings sample is extracted every 0.5 m of drilling, and after grading with a sieve, the weights of each particle size section are weighed. When the proportion of the coarse-grained section in three consecutive samples exceeds 30%, it is determined as a broken zone, and it is located in the tunnel axis coordinate system through the coordinate transformation formula (x = L·sinα·cosβ, y = L·sinα·sinβ, z = L·cosα), with the error controlled within ±0.3 m. After the verification hole is drilled and the endoscope probe is inserted, if the fracture density is greater than 5 fractures per meter and the aperture is greater than 3 mm, the boundary of the broken zone is confirmed.

[0025] Next, three sets of retractable ground-penetrating radar probes are set at the tail of the TBM shield. The three sets of probes are located at the 120-degree position at the top of the shield, the 240-degree position on the left, and the 0-degree position on the right. Each set of probes includes a dual-frequency antenna with transmitting frequencies of 500 MHz and 800 MHz, and the ground-penetrating radar data is collected once every 1 m of cutter head advancement; The advance drilling data and the ground-penetrating radar data are input into the computer control system. When the difference in dielectric constant between the broken zone and the ground-penetrating radar display exceeds 15%, the propulsion speed is automatically reduced to 10 mm / min to 15 mm / min, and at the same time, the cutter head torque is limited to 60% to 70% of the rated value; Specifically, the ground-penetrating radar probe frequency can be selected as 500 MHz, 800 MHz or 1 GHz. The dielectric constant difference threshold is set to 15%, 20% or 25%. The adjustment range of the propulsion speed is 10 - 15 mm / min, and the cutter head torque is limited to 60% - 70% of the rated value.

[0026] The ground-penetrating radar probe can be selected as a dual-frequency retractable probe, and the material is waterproof aluminum alloy. For the data fusion, an industrial computer can be selected, with a built-in data processing module. The dielectric constant calculation uses a weighted algorithm, with a weight of 0.6 for the 500 MHz frequency band and a weight of 0.4 for the 800 MHz frequency band.

[0027] The radar probes are assembled at the tail of the shield. The top probe is located at the azimuth angle of 120 degrees, the left probe is located at the azimuth angle of 240 degrees, and the right probe is located at the azimuth angle of 0 degrees. When the cutter head advances 1 meter, the three groups of probes synchronously collect dual-frequency data and transmit it to the computer. The system calculates the difference between the dielectric constant of the broken zone and the reference value of the intact surrounding rock. If it exceeds 15%, the propulsion speed is automatically reduced to 10 - 15 mm / min, and the cutter head torque is limited to 60% - 70% of the rated value. Data is re-collected every 200 mm of advancement to dynamically update the control parameters.

[0028] During the process of passing through the broken zone, quick-setting cement-sodium silicate double-fluid slurry is injected through the grouting holes reserved at the top of the shield. The grouting pressure is controlled between 0.8 MPa and 1.2 MPa, the water-cement ratio is 0.6:1, the sodium silicate content is 3% - 5% of the cement weight, and the grouting range covers the section 3 - 5 meters behind the cutter head; When tunneling to the water-rich zone, the drainage holes at the center of the cutter head are started. The diameter of the drainage holes is 200 mm, and the negative pressure inside the holes is maintained at -0.05 MPa to -0.08 MPa by a vacuum pump. At the same time, a circumferential water stop is installed outside the shield. The water stop is made of ethylene propylene diene monomer (EPDM) rubber, with a cross-sectional width of 150 mm and a thickness of 12 mm; Specifically, the grouting pressure can be set to 0.8 MPa, 1.0 MPa, or 1.2 MPa. The water-cement ratio can be selected as 0.6:1, 0.55:1, or 0.5:1. The negative pressure of the drainage holes can be adjusted to -0.05 MPa, -0.06 MPa, or -0.08 MPa.

[0029] The grouting pump can be a plunger-type double-fluid grouting pump, and the grouting pipe is made of wear-resistant alloy steel. The water stop can be selected as ethylene propylene diene monomer (EPDM) rubber, with a cross-sectional size of 150 mm × 12 mm. The drainage system can be a rotary vane vacuum pump, and a stainless steel filter screen can be installed on the inner wall of the drainage holes.

[0030] The grouting holes are located at the top of the shield, with a hole diameter of 80 mm. The grouting pipe extends to the area 3 - 5 meters behind the cutter head through a hydraulic propulsion device. The drainage holes are arranged at the center of the cutter head, with a hole diameter of 200 mm. The vacuum pump is connected to the hole opening through a flange. When the water-rich zone is detected, the vacuum pump is started and maintains the negative pressure. The water stop is fixed in the circumferential groove outside the shield by bolts. When grouting, the sodium silicate content is adjusted according to the real-time pressure, and it is automatically increased to 5% when the pressure exceeds the limit.

[0031] When tunneling in the soft interlayer area, steel arch supports are installed 2 meters behind the cutter head. The steel arch supports are made of H-shaped steel, with a cross-sectional height of 180 mm, a flange width of 90 mm, the spacing between adjacent arches is 0.8 - 1.0 meters, and the arches are connected by threaded steel with a diameter of 22 mm. The longitudinal connecting bars are spaced 1.5 meters apart; After each circular tunneling is completed, settlement monitoring targets are installed at the invert of the tunnel. The distance between the targets is 10 meters. The total station is used to measure the three-dimensional coordinates of the targets in real time. When the settlement difference between adjacent targets exceeds 5 millimeters, supplementary grouting is carried out in the corresponding section. The depth of the grouting holes is 3 to 4 meters, and the grouting volume is 0.3 to 0.5 cubic meters per linear meter.

[0032] Specifically, the spacing of the steel arch frames can be set to 0.8 meters, 0.9 meters, or 1.0 meters. The spacing of the targets can be selected as 10 meters, 12 meters, or 15 meters. The settlement difference threshold is 5 millimeters, 6 millimeters, or 7 millimeters.

[0033] The steel arch frames can be made of H-shaped steel with a section height of 180 millimeters and a flange width of 90 millimeters. The longitudinal connecting bars can be made of deformed bars with a diameter of 22 millimeters. The total station can be used for settlement monitoring, and the targets are made of reflective aluminum plates. Single-component cement slurry with a water-cement ratio of 0.6:1 can be used for supplementary grouting.

[0034] The steel arch frames are assembled 2 meters behind the cutter head and installed by a hydraulic manipulator. The arch frames are longitudinally connected with deformed bars at a spacing of 1.5 meters. The targets are fixed at the invert of the tunnel at a spacing of 10 meters, and the total station measures the three-dimensional coordinates in real time. When the settlement difference between adjacent targets exceeds 5 millimeters, supplementary grouting is started. The depth of the grouting holes is 3 - 4 meters, and the grouting volume is 0.3 - 0.5 cubic meters per linear meter.

[0035] In the above embodiments, the advanced drilling and coordinate transformation achieve a positioning accuracy of ±0.3 meters for the fracture zone, reducing the risk of misjudgment. The data fusion of the dual-frequency ground penetrating radar improves the reliability of the detection of the dielectric constant difference, avoiding the interference of a single frequency band. The dynamic adjustment of the grouting pressure and drainage negative pressure effectively controls the stability of the surrounding rock and the water inflow. The linkage between the steel arch frames and settlement monitoring ensures the construction safety in the weak interlayer section and reduces the potential for collapse.

[0036] Furthermore, specifically marking different geological sections according to the particle size distribution, moisture content, and fracture development degree data of the cuttings obtained from the advanced drilling includes: The section with a particle size greater than 50 millimeters accounting for more than 30% is marked as the fracture zone, the section with a moisture content exceeding 25% is marked as the water-rich zone, and the section with a fracture density exceeding 5 fractures per meter is marked as the weak interlayer.

[0037] Specifically, the threshold for the proportion of particles with a size greater than 50 millimeters can be set to 30%, 25%, or 35%. The determination condition for continuous samples can be set to 3 consecutive samples, 2 consecutive samples, or 4 consecutive samples. The screening aperture can be selected as 100 millimeters, 50 millimeters, 20 millimeters, and 5 millimeters. The coordinate positioning error can be controlled within ±0.3 meters, ±0.5 meters, or ±0.2 meters.

[0038] For screening, a standard square-hole sieve can be selected, and the material can be stainless steel or carbon steel. For weighing equipment, an electronic balance can be selected, with a measuring range covering 0 - 10 kg, and the accuracy can be set to ±1 g or ±2 g. For coordinate transformation calculation, an industrial computer can be selected, with a built-in three-dimensional coordinate transformation algorithm. For the verification hole endoscope camera probe, a waterproof camera with a resolution of 1920×1080 pixels can be selected.

[0039] The screening equipment is assembled in the cuttings treatment area behind the drill rig and fixed by a vibration platform. Drill cuttings samples are taken every 0.5 m of drilling. After screening, the weight proportion of each particle size range is calculated. When the proportion of the coarse particle segment in three consecutive samples exceeds 30%, it is determined as a fracture zone. Through the drill pipe inclination angle α and azimuth angle β, the depth L of the starting point of the fracture zone is converted into the three-dimensional coordinates (x = L·sinα·cosβ, y = L·sinα·sinβ, z = L·cosα) in the tunnel axis coordinate system. In the fracture zone area, additional verification holes are drilled, and an endoscope probe is inserted to observe the fracture density and aperture. When the fracture density is greater than 5 fractures / m and the aperture is greater than 3 mm, the boundary of the fracture zone is confirmed.

[0040] The moisture content threshold can be set to 25%, 20% or 30%. The interval for extracting drill cuttings samples can be set to every 0.5 m, 1.0 m or 0.3 m of drilling.

[0041] For moisture content testing, a rapid moisture analyzer can be selected, with a measuring range covering 0 - 100%, and the accuracy can be set to ±0.5%. For the drill cuttings storage container, a sealed plastic bucket can be selected, and the material can be polyethylene.

[0042] The moisture analyzer is assembled on the experimental bench in the cuttings treatment area and connected to the control system through a power cord. After taking a drill cuttings sample every 0.5 m of drilling, 500 g of the sample is put into the analyzer, heated to 105°C and dried to a constant weight, and the moisture content is calculated. When the moisture content exceeds 25%, it is marked as a water-rich zone. The boundary of the water-rich zone is determined by interpolating the moisture content data of adjacent boreholes. The interpolation algorithm can be linear interpolation or Kriging interpolation.

[0043] The fracture density threshold can be set to 5 fractures / m, 4 fractures / m or 6 fractures / m. The fracture aperture threshold can be set to 3 mm, 2 mm or 4 mm.

[0044] For fracture observation, a digital fracture meter can be selected, with a measuring range covering 0 - 10 mm, and the accuracy can be set to ±0.1 mm. The core storage rack can be made of aluminum alloy, with a load-bearing capacity covering 50 kg.

[0045] The fissure meter is assembled in the image processing module of the endoscope probe for the verification hole, and the fissure density is counted through an image recognition algorithm. After extracting the core every 0.5 meters of drilling, the core is placed on the storage rack, and the endoscope probe is used to scan the hole wall to identify the fissure position and measure the aperture. When the fissure density is greater than 5 fissures per meter and the aperture is greater than 3 mm, it is marked as a weak interlayer. The weak interlayer range is determined by superimposing the fissure distribution data of adjacent boreholes.

[0046] In the above embodiments, the spatial positioning of the fracture zone marker is achieved through the particle size ratio and coordinate transformation, reducing the manual judgment error. The determination of the water-rich zone uses a rapid moisture meter to improve the detection efficiency of the moisture content. The weak interlayer marker combines the two parameters of fissure density and aperture to ensure the accuracy of identifying geological anomaly areas.

[0047] Furthermore, the advanced drilling data and the geological radar data are input into the computer control system. When the difference in dielectric constant between the fracture zone and that shown by the geological radar exceeds 15%, the propulsion speed is automatically reduced to 10 mm / min to 15 mm / min, and at the same time, the cutter head torque is limited to 60% to 70% of the rated value. This step specifically includes: The first dielectric constant ε1 at the 500 MHz frequency band and the second dielectric constant ε2 at the 800 MHz frequency band are respectively obtained through the dual-frequency antenna of the geological radar; For the fracture zone area marked by the advanced drilling, the average value of ε1 and the average value of ε2 within the detection range of the geological radar in this area are extracted, and the absolute differences Δε1 = |ε1 - ε0| and Δε2 = |ε2 - ε0| from the reference value ε0 of the intact surrounding rock are respectively calculated; Δε1 and Δε2 are weighted and calculated according to the weight coefficient of 0.6:0.4 to obtain the comprehensive dielectric constant difference Δε = 0.6Δε1 + 0.4Δε2; When Δε > 15%, the computer control system selects control parameters according to the numerical range of Δε: when 15% < Δε ≤ 25%, the propulsion speed is adjusted to 12 mm / min to 15 mm / min, and the cutter head torque is limited to 65% to 70% of the rated value; when Δε > 25%, the propulsion speed is adjusted to 10 mm / min to 12 mm / min, and the cutter head torque is limited to 60% to 65% of the rated value; When the cutter head advances 200 mm each time, the geological radar data is re-acquired to update the Δε value, and the propulsion speed and torque parameters are dynamically adjusted.

[0048] Specifically, the reference value ε0 of the intact surrounding rock is obtained through the following steps: In the tunnel section at least 50 meters away from the fracture zone area, a reference section is selected where the core recovery rate is greater than 90%, the RQD value is greater than 85%, and there is no geological anomaly section with a moisture content greater than 15% or a fissure density greater than 1 fissure per meter; Geological radar measurement points are arranged at intervals of 5 meters along the axis of the tunnel in the reference section, and 10 sets of dielectric constant measurement data are collected in the 500 MHz frequency band and 10 sets of dielectric constant measurement data are collected in the 800 MHz frequency band using a dual-frequency antenna; The Grubbs criterion was used to eliminate outliers in each set of measurement data. When the measured value deviated from the mean value of the group by more than 3 standard deviations, the abnormal measured value was deleted. The arithmetic mean of the effective measurement data in the 500MHz frequency band is calculated as ε01, and the arithmetic mean of the effective measurement data in the 800MHz frequency band is calculated as ε02; ε01 and ε02 are synthesized at a weight ratio of 0.7:0.3, and the comprehensive benchmark value ε0=0.7×ε01+0.3×ε02 is calculated; After completing every 200 meters of tunnel excavation, the benchmark section selection and measurement steps are re-executed. When the newly obtained ε0 value deviates from the original value by more than 8%, the geological radar system calibration procedure is started and the geological conditions of the benchmark section are reviewed.

[0049] Here, the broken zone is determined by the proportion of coarse-grained segments in three consecutive rock cuttings samples to avoid accidental errors in a single sample. The standardized process of extracting and screening samples every 0.5 meters of drilling ensures the systematic and consistent data collection and reduces the risk of human misjudgment. Based on the coordinate conversion formula of the drill rod inclination and azimuth, the broken zone depth is mapped to the tunnel axis coordinate system, and the positioning error is controlled within ±0.3 meters. This method achieves three-dimensional positioning of geological anomaly areas through mathematical modeling, providing an accurate basis for subsequent construction parameter adjustments. Verification holes are drilled in the broken zone area and endoscopic camera probes are inserted to confirm the broken zone boundary by directly observing the dual parameters of the density and opening of the hole wall cracks. This step combines rock cuttings data with visual detection to form a cross-validation mechanism to avoid the limitations of relying solely on a single data source. The broken zone range mark is dynamically corrected through coordinate error control and real-time feedback of measured crack data. This process enables the construction plan to flexibly respond to local changes in surrounding rock conditions and improve the adaptability and safety of excavation in poor areas.

[0050] Specifically, the marking method of the broken zone includes: During the advance drilling process, rock cuttings samples were extracted every 0.5 m of drilling, and dry sieving was performed using standard square hole sieves with apertures of 100 mm, 50 mm, 20 mm, and 5 mm. The coarse grains with a particle size greater than 50 mm were weighed and their proportion was calculated. When the proportion of coarse grains in three consecutive samples exceeded 30%, it was determined to be a broken zone. According to the drill pipe dip angle α and azimuth angle β, the depth L of the starting point of the broken zone is converted into the three-dimensional coordinates of the tunnel axis coordinate system. The conversion formula is x = L·sinα·cosβ, y = L·sinα·sinβ, and z = L·cosα. The coordinate positioning error is controlled within ±0.3 meters. Verification holes are drilled and inserted with endoscopic camera probes in the broken zone area. When the observed fracture density is greater than 5 fractures per meter and the aperture is greater than 3 mm, the boundary range of the broken zone is confirmed.

[0051] Here, by selecting a complete surrounding rock section with a core recovery rate > 90%, an RQD value > 85%, and no water content > 15% or fracture density > 1 fracture per meter as the reference section, geological anomaly interference is excluded to ensure the reliability of the reference value ε0. The strict screening conditions enable ε0 to truly reflect the dielectric properties of the complete surrounding rock and provide a stable reference for subsequent broken zone determination. In the reference section, measurement points are arranged every 5 meters along the tunnel axis, and 10 groups of dielectric constant data in the frequency bands of 500 MHz and 800 MHz are collected respectively. Through the complementarity of dual-frequency data and the elimination of outliers in combination with the Grubbs criterion, the influence of single-frequency band or accidental errors is effectively reduced. Finally, the comprehensive reference value ε0 is synthesized according to a weight of 0.7:0.3, taking into account the detail resolution of high-frequency data and the depth penetration ability of low-frequency data, and improving the scientificity and adaptability of the reference value. After every 200 meters of tunneling, the reference value measurement is re-executed, and the system calibration is triggered according to the deviation between the new reference value and the original value. This mechanism can dynamically adapt to the gradual change or local change of the surrounding rock conditions (such as stress adjustment, fracture development), and avoid the invalidation of the reference value caused by geological environment changes. At the same time, the calibration procedure combines geological review to further verify the data validity and ensure the accuracy of the dielectric constant difference calculation during the entire construction period. The accurate acquisition of the dielectric constant reference value of the complete surrounding rock lays the foundation for calculating the dielectric constant difference (Δε) between the broken zone and the ground penetrating radar data. By comparing Δε with the threshold value, the system can automatically adjust the propulsion speed and cutter head torque to prevent equipment overload or collapse risks caused by sudden changes in the surrounding rock. The dynamic update of the reference value further enhances the real-time performance and adaptability of construction parameter control, thereby improving the tunneling efficiency and safety of the TBM in poor ground sections.

[0052] In the above embodiments, the weighted fusion of dual-frequency data improves the detection accuracy of the dielectric constant difference and reduces the risk of single-frequency band interference. Dynamically adjusting the propulsion speed and torque parameters adapts to different geological conditions and reduces abnormal loads on the cutter head. Regularly calibrating the reference value ensures data reliability and adapts to the dynamic changes of the surrounding rock conditions. The outlier elimination and multi-source verification mechanism improve the accuracy of broken zone determination.

[0053] Furthermore, the injection control of the quick-setting cement-sodium silicate double-fluid slurry includes the following steps: Install a distributed optical fiber pressure sensor in the grouting hole, and arrange a measuring point every 0.5 meters along the hole depth direction to monitor the slurry diffusion pressure distribution in real time; Select the grouting mode according to the ratio of the length L of the marked area of the fracture zone to the cutter head diameter D: when L / D < 0.5, continuous grouting is adopted, and the grouting speed is maintained at 8 L / min to 10 L / min; when L / D ≥ 0.5, pulse grouting is adopted, and it alternates with a cycle of 30 seconds of grouting / 15 seconds of intermittent pause; The slurry ratio is closed-loop controlled by an electromagnetic flowmeter and a pressure transmitter on the grouting pipeline. When the real-time pressure exceeds the set pressure upper limit of 1.2 MPa, the sodium silicate admixture is automatically adjusted to the upper limit value of 5%. When the pressure is lower than 0.8 MPa, the water-cement ratio is synchronously reduced to 0.55:1; Arrange a borehole coring verification point 5 meters behind the cutter head, and use a drill bit with a diameter of 100 mm to obtain the core sample of the grouted body. When the core sample strength is lower than 20 MPa or the permeability coefficient is greater than 1×10 -7 cm / s, inject a sodium silicate strengthening slurry with an admixture of 7% at adjacent grouting holes.

[0054] In the above embodiment, distributed fiber optic pressure sensors are installed in the grouting holes, and measuring points are arranged at intervals of 0.5 meters along the hole depth direction to monitor the slurry diffusion pressure distribution in real time. This technical means can accurately capture the pressure changes at different depths during the grouting process, avoiding slurry overflow caused by excessive local pressure or incomplete filling caused by insufficient pressure. For example, when the real-time pressure exceeds the set upper limit of 1.2 MPa, the sodium silicate admixture is automatically adjusted to 5% to reduce the slurry setting speed; when the pressure is lower than 0.8 MPa, the water-cement ratio is reduced to 0.55:1 to improve fluidity. This closed-loop control mechanism ensures that the grouting pressure is stable within a reasonable range and improves the surrounding rock reinforcement effect.

[0055] Select the grouting mode according to the ratio of the fracture zone length L to the cutter head diameter D: when L / D < 0.5, continuous grouting is adopted, which is suitable for rapid filling of short-distance fracture zones; when L / D ≥ 0.5, switch to pulse grouting to relieve the slurry diffusion resistance in long-distance fracture zones through intermittent operation. This mode switching mechanism can optimize the grouting efficiency according to different fracture zone scales, reduce slurry waste and lower the risk of pipe blockage.

[0056] Arrange a borehole coring verification point 5 meters behind the cutter head, and use a drill bit with a diameter of 100 mm to obtain the core sample of the grouted body, and detect its strength and permeability coefficient. When the core sample strength is lower than 20 MPa or the permeability coefficient is greater than 1×10 -7 cm / s, inject a sodium silicate strengthening slurry with an admixture of 7% at adjacent holes. This step verifies the actual performance of the grouted body through physical sampling, ensures that the reinforcement quality meets the standards, and avoids instability of the surrounding rock caused by local defects.

[0057] Link the electromagnetic flowmeter and the pressure transmitter on the grouting pipeline to adjust the sodium silicate dosage and water-cement ratio in real time. For example, when the pressure exceeds the limit, increase the sodium silicate dosage to accelerate coagulation; when the pressure is insufficient, decrease the water-cement ratio to improve fluidity. This dynamic adjustment mechanism can adapt to the grouting requirements under complex geological conditions, maintain the optimal working state of the slurry, and thus improve the overall reinforcement effect in the fractured zone area.

[0058] Although the embodiments of the present invention have been disclosed as above, it is not limited to the applications listed in the specification and embodiments. It can be fully applied to various fields suitable for the present invention. For those familiar with the field, additional modifications can be easily made. Therefore, without departing from the general concept defined by the claims and the equivalent scope, the present invention is not limited to the specific details and the embodiments shown and described herein.

Claims

1. A construction method for TBM tunneling in poor ground sections, characterized in that, It includes the following steps: Implement advanced drilling within a range of 30 to 50 meters in front of the TBM cutterhead. Use a borehole with a diameter of 100 mm. The boreholes are arranged circumferentially at an interval of 30 degrees along the tunnel axis, and the borehole depth is 15 to 20 meters. During the drilling process, record the particle size distribution, water content, and the degree of rock formation fissure development of the cuttings; Mark different geological sections according to the particle size distribution, water content, and the degree of rock formation fissure development data of the cuttings obtained from the advanced drilling. The geological sections include fracture zones, water-rich zones, and weak interlayers; Set three groups of retractable ground-penetrating radar probes at the tail of the TBM shield. The three groups of probes are located at the 120-degree position on the top of the shield, the 240-degree position on the left, and the 0-degree position on the right. Each group of probes includes a dual-frequency antenna with transmitting frequencies of 500 MHz and 800 MHz. Collect ground-penetrating radar data once every 1 meter of cutterhead advancement; Input the advanced drilling data and ground-penetrating radar data into the computer control system. When the difference in dielectric constant between the fracture zone and that shown by the ground-penetrating radar exceeds 15%, automatically reduce the advancement speed to 10 to 15 mm / min, and at the same time limit the cutterhead torque to 60% to 70% of the rated value; During the process of passing through the fracture zone, inject quick-setting cement-sodium silicate double-fluid slurry through the grouting holes reserved on the top of the shield. Control the grouting pressure at 0.8 to 1.2 MPa, the water-cement ratio at 0.6:1, and the sodium silicate content at 3% to 5% of the cement weight. The grouting range covers the section 3 to 5 meters behind the cutterhead; When tunneling to the water-rich zone, start the drainage holes at the center part of the cutterhead. The diameter of the drainage holes is 200 mm. Maintain the negative pressure in the holes at -0.05 to -0.08 MPa through a vacuum pump. At the same time, install a circumferential water stop on the outside of the shield. The water stop is made of ethylene propylene diene monomer (EPDM) rubber, with a cross-sectional width of 150 mm and a thickness of 12 mm; When tunneling in the weak interlayer area, install steel arch supports 2 meters behind the cutterhead. The steel arch supports are made of H-shaped steel, with a cross-sectional height of 180 mm, a flange width of 90 mm. The spacing between adjacent arches is 0.8 to 1.0 meters. The arches are connected by threaded steel with a diameter of 22 mm, and the longitudinal connecting bars are spaced 1.5 meters apart; After each cycle of tunneling is completed, install settlement monitoring targets at the invert part of the tunnel. The target spacing is 10 meters. Use a total station to measure the three-dimensional coordinates of the targets in real time. When the settlement difference between adjacent targets exceeds 5 mm, supplement grouting in the corresponding section. The grouting hole depth is 3 to 4 meters, and the grouting volume is 0.3 to 0.5 cubic meters per linear meter.

2. The construction method of TBM tunneling in poor sections as described in claim 1, characterized in that, Marking different geological sections according to the particle size distribution, water content, and the degree of rock formation fissure development data of the cuttings obtained from the advanced drilling specifically includes: Mark the section where the proportion of particles larger than 50 mm exceeds 30% as the fracture zone, mark the section where the water content exceeds 25% as the water-rich zone, and mark the section where the fracture density exceeds 5 fractures per meter as the weak interlayer.

3. The construction method of TBM tunneling in poor sections as described in claim 2, characterized in that, Input the advanced drilling data and the ground penetrating radar data into the computer control system. When the difference in dielectric constant between the fractured zone and that shown by the ground penetrating radar exceeds 15%, automatically reduce the propulsion speed to 10 mm / min to 15 mm / min, and at the same time limit the cutter head torque to 60% to 70% of the rated value. This step specifically includes: Obtain the first dielectric constant ε1 in the 500 MHz frequency band and the second dielectric constant ε2 in the 800 MHz frequency band respectively through the dual-frequency antenna of the ground penetrating radar; For the fractured zone area marked by the advanced drilling, extract the average value of ε1 and the average value of ε2 within the detection range of the ground penetrating radar in this area, and calculate the absolute differences Δε1 = |ε1 - ε0| and Δε2 = |ε2 - ε0| from the reference value ε0 of the intact surrounding rock respectively; Perform weighted calculation on Δε1 and Δε2 with a weight coefficient of 0.6:0.4 to obtain the comprehensive dielectric constant difference Δε = 0.6Δε1 + 0.4Δε2; When Δε > 15%, the computer control system selects control parameters according to the numerical range of Δε: when 15% < Δε ≤ 25%, adjust the propulsion speed to 12 mm / min to 15 mm / min, and limit the cutter head torque to 65% to 70% of the rated value; when Δε > 25%, adjust the propulsion speed to 10 mm / min to 12 mm / min, and limit the cutter head torque to 60% to 65% of the rated value; When the cutter head advances 200 mm each time, re-collect the ground penetrating radar data to update the value of Δε, and dynamically adjust the propulsion speed and torque parameters.

4. The construction method for TBM tunneling in poor ground sections as described in claim 3, characterized in that, The marking method of the fractured zone includes: During the advanced drilling process, extract a rock chip sample every 0.5 m of drilling. Use standard square-hole sieves with apertures of 100 mm, 50 mm, 20 mm, and 5 mm for dry screening and grading. Weigh the weight of the coarse-grained section with a particle size greater than 50 mm and calculate the proportion. When the proportion of the coarse-grained section in three consecutive samples exceeds 30% each time, it is determined as the fractured zone; According to the drill pipe inclination angle α and azimuth angle β, convert the starting point depth L of the fractured zone into the three-dimensional coordinates of the tunnel axis coordinate system. The conversion formula is x = L·sinα·cosβ, y = L·sinα·sinβ, z = L·cosα, and the coordinate positioning error is controlled within ±0.3 m. Drill verification holes in the fractured zone area and insert an endoscopic camera probe. When the observed fracture density is greater than 5 fractures / m and the aperture is greater than 3 mm, confirm the boundary range of the fractured zone.

5. The method for TBM tunneling construction in poor sections as described in claim 3, characterized in that, The reference value ε0 of the intact surrounding rock is obtained through the following steps: In the tunnel section at least 50 m away from the fractured zone area, select a geological anomaly section with a core recovery rate greater than 90%, an RQD value greater than 85%, and no water content greater than 15% or fracture density greater than 1 fracture / m as the reference section; Arrange ground penetrating radar measurement points along the tunnel axis at intervals of 5 m in the reference section. Use the dual-frequency antenna to collect 10 groups of dielectric constant measurement data in the 500 MHz frequency band and 10 groups of dielectric constant measurement data in the 800 MHz frequency band; Adopt the Grubbs criterion to eliminate outliers from each group of measurement data. When the measured value deviates from the average value of this group by more than 3 times the standard deviation, delete this abnormal measured value; Calculate the arithmetic mean of the effective measurement data in the 500 MHz frequency band as ε01, and calculate the arithmetic mean of the effective measurement data in the 800 MHz frequency band as ε02; Synthesize ε01 and ε02 according to the weight ratio of 0.7:0.3, and calculate the comprehensive reference value ε0 = 0.7×ε01 + 0.3×ε02; After every 200 meters of tunnel boring is completed, re-execute the reference section selection and measurement steps. When the deviation between the newly obtained ε0 value and the original value exceeds 8%, start the calibration program of the ground penetrating radar system and review the geological conditions of the reference section.

6. The method for TBM tunneling construction in poor sections as described in claim 1, wherein The injection control of the quick-setting cement-sodium silicate double-fluid grout includes the following steps: Install a distributed fiber optic pressure sensor in the grouting hole, arrange a measuring point every 0.5 meters along the hole depth direction, and monitor the slurry diffusion pressure distribution in real time; Select the grouting mode according to the ratio of the length L of the marked area of the broken zone to the cutter head diameter D: when L / D < 0.5, continuous grouting is used, and the grouting speed is maintained at 8 L / min to 10 L / min; when L / D ≥ 0.5, pulse grouting is used, and it alternates with a cycle of 30 seconds of grouting / 15 seconds of intermittent; Closed-loop control the slurry ratio through the electromagnetic flowmeter and pressure transmitter on the grouting pipeline. When the real-time pressure exceeds the set pressure upper limit of 1.2 MPa, automatically adjust the sodium silicate dosage to the upper limit value of 5%. When the pressure is lower than 0.8 MPa, synchronously reduce the water-cement ratio to 0.55:1; Drilling and coring verification points are arranged 5 meters behind the cutter head, and core samples of the grouting body are obtained using a drill bit with a diameter of 100 mm. When the core sample strength is lower than 20 MPa or the permeability coefficient is greater than 1×10 -7 cm / s, additional injection of water glass enhanced slurry with an admixture of 7% is carried out at adjacent grouting hole positions.