Long-distance small-diameter shield tunneling measurement method

Abstract

The application discloses a long-distance small-diameter shield tunneling measurement method and relates to the shield tunneling field, which comprises the following steps: carrying out the re-measurement of the original control point and the encryption control point plane control network and the elevation control network outside the hole, and establishing a hole outside measurement datum; based on the hole outside measurement datum, arranging the control points around the working well, and performing periodic re-measurement, wherein the working well comprises a starting well L3 and a receiving well L2; using the multi-medium coordinate transfer to complete the contact measurement between the well and the underground, introducing the ground measurement datum into the underground, and then introducing the elevation control point near the well mouth into the working well by using the inverted scale method. The application effectively solves the receiving deviation problem of the long-distance small-diameter shield curve segment caused by error accumulation through the whole process layered measurement steps of the hole outside datum establishment, the periodic re-measurement of the working well control point, the contact measurement between the well and the underground, the whole hole closed traverse measurement and the post-penetration traverse rechecking, and the high-precision penetration of the >=2km long-distance tunneling is ensured.

Description

Technical Field

[0001] This invention relates to the field of tunnel boring machines (TBMs), and particularly to a measurement method for long-distance, small-diameter TBM tunneling. Background Technology

[0002] Tunnel boring machine (TBM) is a mechanized and automated technology that uses a TBM to construct underground tunnels. The core of TBM tunneling is to use the rotating cutterhead of the TBM to cut through the soil or rock, while using a support system to maintain the stability of the excavation face, ultimately forming a continuous and safe tunnel structure. During the TBM tunneling process, long-distance, small-diameter TBM tunneling is usually carried out, especially in curved sections with a length of ≥2km, which requires measurement operations for long-distance, small-diameter TBM tunneling.

[0003] Existing measurement methods are often affected by factors such as narrow tunnel space, short guide wire side length, and accumulated angle observation errors. Furthermore, they lack a targeted static high-precision re-measurement process, resulting in insufficient accuracy of the reference data and an inability to support the stable transmission of long-distance coordinates. Therefore, it is necessary to use a measurement method that has full-process layered control and is adapted to long-distance small-diameter shield tunneling. Summary of the Invention

[0004] The purpose of this invention is to provide a measurement method for long-distance, small-diameter shield tunneling, in order to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a measurement method for long-distance, small-diameter shield tunneling, comprising the following specific steps: Step 1: Conduct a resurvey of the existing control points and densified control points outside the tunnel, including the horizontal and vertical control networks, and establish a measurement benchmark outside the tunnel; Step 2: Based on the external measurement benchmark established in Step 1, set up control points around the working shaft and perform periodic re-measurements. The periodic re-measurements include both horizontal and vertical measurements. The working shaft includes the launching shaft L3 and the receiving shaft L2. Step 3: Use multi-media coordinate transfer to complete the connection measurement between the surface and underground, and import the ground measurement benchmark into the underground. Then, use the inverted ruler method to introduce the elevation control points near the wellhead into the working shaft as the starting elevation for tunnel excavation, and check them regularly. Step 4: Simultaneously conduct closed traverse surveys within the tunnel throughout the entire shield tunneling process to monitor the accuracy of the tunneling process in real time. When the shield tunneling reaches 200m, set a tray point at the arch waist of the segment at 6m from the tunnel entrance and a control point on the bottom plate of the segment at 200m. Conduct connection measurements between the inside and outside of the tunnel and perform gyro orientation verification. Use these two points as the starting edge of the traverse within the tunnel. Perform a second gyro orientation verification when the tunnel reaches 1 / 3 of its length. Step 5: When there is 150m left in the tunnel, prepare to carry out the connection measurement and the traverse measurement inside the tunnel before the tunnel breakthrough. Perform gyro orientation verification on the control points outside the tunnel. Then, use the control points outside the tunnel to make a traverse to the near well point to ensure the accuracy of the starting edge of the traverse. Combine the traverse points of the segment layout to carry out gyro orientation verification and correct the measurement accuracy inside the tunnel. Step 6: Before the tunnel is completed, set up the end guide points within a preset distance from the L2 exit end of the receiving shaft and complete the calibration. After the closed guide is completed in the tunnel before the tunnel is completed, the receiving shaft will use the connection measurement to introduce the plane coordinates and elevation of the ground points into the receiving shaft, and complete the measurement of the actual coordinates of the steel ring of the receiving shaft portal. During the advancement process, the shield attitude is adjusted according to the actual coordinates of the receiving shaft until the tunnel is completed. Step 7: After the tunnel is completed and the shield machine is lifted out of the receiving shaft, selectively carry out traverse surveying to verify the breakthrough accuracy.

[0006] Preferably, the retesting and density-increasing deployment in step one specifically includes: S1: Use GNSS static measurement to remeasure the original control points outside the tunnel, with an observation time of no less than 60 minutes and baseline calculation accuracy controlled at ±2mm+1ppm; S2: Based on the remeasured control points outside the tunnel in S1, additional control points outside the tunnel are set up, with the positional error of the additional control points not exceeding ±3mm.

[0007] Preferably, the layout and periodic re-measurement of surrounding control points in step two specifically include: SS1: Using the re-measured control points and densified points outside the tunnel, a total station is used to set up control points around the working shaft; SS2: Before each well-to-downhole connection measurement in step three, the control points around the working well must be remeasured. If the deviation of the remeasured point exceeds ±3mm, the control points around the well need to be re-established.

[0008] Preferably, the surface-to-downhole connection measurement in step three specifically includes: SSS1: At least three indium steel wires are suspended at the wellhead of the working well, and the diameter of the indium steel wires is ≤0.5mm, to serve as the coordinate transmission medium between the ground and the well. SSS2: A total station with an accuracy of no less than 1″ is used for both the surface and downhole operations to simultaneously observe the distance and angle of the indium wire. SSS3: Transmits the coordinates of ground control points to the downhole via indium wire observation data, thus establishing the initial measurement benchmark in the downhole.

[0009] Preferably, the closed traverse measurement inside the tunnel in step four specifically includes: SSSS1: During the tunnel boring machine excavation process, a total station with an accuracy class of not less than 1″ is used to carry out closed traverse surveying inside the tunnel; SSSS2: Closed traverse surveying covers the entire tunneling section from the launching shaft L3 to the receiving shaft L2, and advances synchronously with the tunnel boring machine (TBM) excavation, with no measurement interruptions.

[0010] Preferably, the traverse measurement in step five specifically includes, before conducting the final closed traverse measurement inside the tunnel, calibrating the starting traverse edge outside the tunnel using gyroscope orientation, then using the control points outside the tunnel to verify the traverse near the well point, and comparing the gyroscope orientation result with the closed traverse measurement result in step four. If the deviation exceeds ±5mm, the accuracy of the closed traverse needs to be adjusted. After the verification is completed, a connection measurement between the surface and underground is performed to determine the coordinates of the two points of the starting edge of the traverse inside the tunnel, thus completing the verification of the starting edge of the traverse inside the tunnel.

[0011] Preferably, step five includes: After the tunnel boring machine has advanced 200 meters, the first connection measurement is carried out, including gyro orientation, to establish a reliable starting point for subsequent tunneling. When the tunnel boring machine has tunneled to 1 / 3 of the breakthrough length, a second gyro-guided verification is performed. When the tunnel boring machine is about 150 meters away from the breakthrough surface, a third gyro orientation check is performed; If the tunnel length is ≥1.5km, the gyroscope orientation frequency needs to be increased.

[0012] Preferably, the requirements for setting up the traverse points for the tunnel segments in step five are as follows: embedded traverse points are set up at the bottom plate of the tunnel segments at 200m, 1 / 3 of the tunnel length, 150m from the receiving end, and other key ring numbers, with an accuracy of not less than ±1mm, serving as dual control points for gyro orientation and tunnel traverse; other tunnel traverse points are not placed on the arch waist tray of the tunnel segments, and the side length of the traverse should be controlled between 150 and 300m to reduce the number of stations. The side length of the traverse should be appropriately shortened where the curve is not visible.

[0013] Preferably, step six specifically includes: F1: Before the tunnel is completed, the last in-tunnel guide point shall be set up at a location no more than 150 meters from the exit end of the receiving shaft L2. F2: For the last traverse point inside the tunnel, simultaneously carry out the closed traverse measurement in step four and the gyroscope orientation verification in step five, ensuring that the positional error of the point does not exceed ±4mm.

[0014] Preferably, the traverse measurement in step seven specifically includes: G1: After the tunnel is completed and the shield machine is lifted out of the receiving shaft L2, conduct traverse survey and leveling survey to verify the integrity of the data and guide subsequent shield section surveying work. G2: The traverse line is formed with the control points around the receiving well L2 as a reference, and the last traverse point in step six is ​​used to form the traverse line. The proposed connection point is determined, and the horizontal connection error and the vertical connection error are analyzed to provide experience for the subsequent connection measurement and traverse measurement of other sections.

[0015] The technical effects and advantages of this invention are as follows: (1) This invention forms a closed loop of precision control covering the entire tunneling cycle through the following steps: establishing benchmarks outside the tunnel, periodically re-measuring control points in the working shaft, measuring the connection between the above-ground and underground tunnels, measuring the closed traverse in the tunnel, gyroscope orientation verification, precise layout of end traverse points, and post-tunneling attachment and traverse verification. This effectively solves the problem of receiving deviation caused by error accumulation in long-distance, small-diameter shield tunneling curves, and ensures high-precision tunneling of ≥2km long-distance tunneling. (2) This invention utilizes GNSS static measurement to conduct re-measurement of control points outside the tunnel and to set up densified points, and clarifies the accuracy control parameters. This is conducive to the high-precision establishment of the measurement benchmark outside the tunnel, and provides a reliable initial basis for subsequent full-process measurement, which is conducive to improving the accuracy of the measurement benchmark. (3) This invention establishes a periodic re-measurement mechanism for control points around the working well and adopts a setting method with at least three indium steel wires. It also clarifies the re-measurement deviation threshold and the conditions for re-layout. This helps to prevent the reference offset of control points caused by environmental disturbances and structural deformation, and helps to ensure the reference stability of the connection measurement between the surface and the well. The coordinate transfer method of multiple indium steel wires combined with the synchronous observation of dual high-precision total stations on the surface and the well helps to significantly reduce the system error and environmental interference of single medium transmission, and facilitates the accurate import of the ground reference to the well, thereby improving the reliability of the connection measurement. (4) This invention utilizes closed traverse measurement throughout the tunnel excavation process, and embeds embedded markers on the bottom plate of the tunnel lining that function as both traverse points and gyroscope orientation check points. It also specifies a distance threshold of no more than 180 meters between the end traverse point before tunnel breakthrough and the exit end of the receiving shaft. Furthermore, it performs dual precision calibration on the traverse point simultaneously, thereby strengthening the end precision control before tunnel breakthrough and providing a precise attitude reference for the accurate reception of the shield. At the same time, it combines the tunneling length threshold to dynamically adjust the check frequency, forming a dynamic control mechanism of measurement-check-adjustment, which effectively suppresses the accumulation of errors in small space curve segments. (5) This invention utilizes the selective initiation mechanism of the connection and traverse measurement after the connection is completed, and clarifies the threshold for the closure error judgment and the corresponding shield attitude adjustment process, which is conducive to the standardized verification of the connection accuracy and the targeted handling of deviations, thereby improving the efficiency and standardization of deviation resolution. Furthermore, the standardized layout of the traverse points in the key ring segments and the embedded identification design improve the anti-interference ability and observation accuracy of the traverse points, which helps to prevent the problems of easy damage and difficult identification of traditional traverse points, and ensures the continuity and stability of the measurement process. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the measurement process for long-distance, small-diameter shield tunneling according to the present invention; Figure 2 This is a schematic diagram showing the process from the start of tunneling to the completion of the closed traverse in this invention. Figure 3 This is a schematic diagram of the attached conductor after the equipment is hoisted out of the receiving well L2 after the breakthrough of the present invention; Figure 4 This is a schematic diagram of the starting well L2 on the closed conductor of the present invention; Figure 5 This is a schematic diagram of the last conductor point on the closed conductor of the present invention; Figure 6 This is a schematic diagram of the receiving well L2 on the closed conductor of the present invention; Figure 7 This is a schematic diagram of the starting well L3 on the guide wire of the present invention; Figure 8 This is a schematic diagram of the tail end of the attached wire in this invention; Figure 9 This is a schematic diagram of the receiving well L2 on the attached conductor of the present invention. Detailed Implementation

[0017] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] This invention provides, for example Figures 1-9 The method for measuring long-distance, small-diameter shield tunneling, as shown, includes the following specific steps: Step 1: Conduct a resurvey of the existing control points and densified control points outside the tunnel, including the horizontal and vertical control networks, and establish a measurement benchmark outside the tunnel; Step Two: Based on the external measurement benchmark established in Step One, establish control points around the working shaft and perform periodic re-measurements. These periodic re-measurements include both horizontal and vertical measurements. The working shaft includes the launching shaft L3 and the receiving shaft L2. The area between L3 and L2 is the shield tunnel section. The method for establishing the traverse points is as follows: External densification points: Location selection: Established in areas with good visibility and far from interference sources (such as high-voltage lines or large equipment); Marking method: Use buried stone markers, with a stainless steel forced centering disc embedded in the top of the marker (centering accuracy ≤1mm); Control points around the working shaft: Location selection: Established at the edge of the working shaft pit. At a distance of 10m-20m, to avoid the impact of foundation pit deformation; Marking method: a combination of ground-engraved stone and forced centering plate, with an engraving depth of not less than 20cm; In-tunnel segment guide points: Location selection: placed in the center area of ​​the segment bottom plate (avoiding segment joints), with additional markings required for critical ring numbers; Marking method: embedded stainless steel signs (thickness ≥5mm), fixed to the segment bottom plate with expansion bolts, with crosshairs engraved in the center of the sign (accuracy ≤0.5mm); Protection measures: wear-resistant protective film is pasted on the surface of the sign to prevent damage from debris and equipment during shield tunneling; Step 3: Use multi-media coordinate transfer to complete the connection measurement between the surface and underground, and import the ground measurement benchmark into the underground. Then, use the inverted ruler method to introduce the elevation control points near the wellhead into the working shaft as the starting elevation for tunnel excavation, and check them regularly. Step 4: Simultaneously conduct closed traverse surveys within the tunnel throughout the entire shield tunneling process to monitor the accuracy of the tunneling process in real time. When the shield tunneling reaches 200m, set a tray point at the arch waist of the segment at 6m from the tunnel entrance and a control point on the bottom plate of the segment at 200m. Conduct connection measurements between the inside and outside of the tunnel and perform gyro orientation verification. Use these two points as the starting edge of the traverse within the tunnel. Perform a second gyro orientation verification when the tunnel reaches 1 / 3 of its length. Step 5: When there is 150m left in the tunnel, prepare to carry out the connection measurement and the traverse measurement inside the tunnel before the tunnel breakthrough. Perform gyro orientation verification on the control points outside the tunnel. Then, use the control points outside the tunnel to make a traverse to the near well point to ensure the accuracy of the starting edge of the traverse. Combine the traverse points of the segment layout to carry out gyro orientation verification and correct the measurement accuracy inside the tunnel. Step 6: Before the tunnel is completed, set up the end guide points within a preset distance from the L2 exit end of the receiving shaft and complete the calibration. After the closed guide is completed in the tunnel before the tunnel is completed, the receiving shaft will use the connection measurement to introduce the plane coordinates and elevation of the ground points into the receiving shaft, and complete the measurement of the actual coordinates of the steel ring of the receiving shaft portal. During the advancement process, the shield attitude is adjusted according to the actual coordinates of the receiving shaft until the tunnel is completed. Step 7: After the tunnel is completed and the shield machine is lifted out of the receiving shaft, selectively carry out traverse surveying to verify the breakthrough accuracy.

[0019] Specifically, the re-measurement and density increase deployment in step one includes: S1: GNSS static measurement will be used to remeasure the existing control points outside the tunnel, with an observation duration of no less than 60 minutes and a baseline calculation accuracy controlled within ±2mm + 1ppm. The specific operation of GNSS static measurement is as follows: At least four dual-frequency GNSS receivers (accuracy level no less than millimeter) will be selected, equipped with tripods, centering devices, and windproof covers; Pre-observation preparation: Instruments will be set up at the existing control points and the proposed densification points outside the tunnel. After centering and leveling, the instrument height, observation time, and ambient temperature will be recorded; Observation process: A synchronous observation mode will be adopted, with an observation duration of no less than 60 minutes per station and a sampling interval of 15 seconds; interference from personnel and equipment with the receiver signal will be avoided during the observation process; Data processing: Baseline calculation will be performed using professional GNSS calculation software (such as Trimble Business Center), with a calculation accuracy controlled within ±2mm + 1ppm; The calculated control point coordinates will be adjusted to ensure that the positional error of the densification points does not exceed ±3mm. The adjusted results must be verified through field remeasurement. S2: Based on the remeasured control points outside the tunnel in S1, additional control points outside the tunnel are set up, with the positional error of the additional control points not exceeding ±3mm.

[0020] Furthermore, the establishment and periodic re-measurement of surrounding control points in step two specifically include: SS1: Using the re-measured control points and densified points outside the tunnel, a high-precision total station is used to set up control points around the working well. The high-precision total station is used as follows: Station setup: Using the control points re-measured outside the tunnel as known points, the total station is centered and leveled; Observation: Horizontal angle, vertical angle, and distance observations are performed on the control points around the working well. The horizontal angle observations are performed at least 4 times, and the distance observations are performed at least 3 times; Data verification: During the re-measurement, the new observation data is compared with the original results. If the point deviation exceeds ±3mm, the control points are re-set up and the observations are repeated. SS2: Before each well-to-downhole connection measurement in step three, the control points around the working well must be remeasured. If the deviation of the remeasured point exceeds ±3mm, the control points around the well need to be re-established.

[0021] Specifically, the surface-to-downhole connection measurement in step three includes: SSS1: At least three indium steel wires with a diameter ≤0.5mm are suspended at the wellhead of the working shaft to serve as the coordinate transfer medium between the ground and the shaft. The specific use of indium steel wires is as follows: Material selection: The selected indium steel wire has a low coefficient of thermal expansion and high tensile strength to avoid temperature deformation and tensile deformation; Suspension device: A special suspension frame is set at the wellhead of the working shaft. One end of the indium steel wire is fixed to the frame (the fixing point must be precisely aligned with the ground control point), and a plumb weight is suspended at the other end (the weight mass ≥5kg to ensure the steel wire is vertical); Verticality control: During the suspension process, a plumb line is used to monitor the verticality of the steel wire. If the deviation exceeds 2mm, the suspension position is adjusted; At least three indium steel wires are suspended in each well, with a spacing of not less than 1m between the wires to avoid mutual interference. The function of the indium steel wire is to serve as the coordinate transfer medium between the ground and the shaft. Utilizing the low deformation characteristics of the indium steel wire, the coordinates of high-precision control points on the ground are accurately transferred to the shaft, solving the accuracy problem of ground-to-shaft benchmark connection in small-diameter tunnels; SSS2: One high-precision total station is used both above and below ground to simultaneously observe the distance and angle of the indium wire. The operation of the high-precision total station is as follows: Simultaneous observation: One identical total station is deployed above ground and one below ground to simultaneously observe the angle and distance of the suspended indium wire; Observation requirements: Horizontal angle observations should be conducted at least 6 times, and distance observations should be conducted using a forward and backward measurement method, with at least 4 observations per round trip; Results transfer: The coordinates of the indium wire observed above ground are converted to the underground coordinate system to complete the transfer of the ground reference to the underground system; SSS3: Transmits the coordinates of ground control points to the downhole via indium wire observation data, thus establishing the initial measurement benchmark in the downhole.

[0022] Furthermore, the closed traverse measurement inside the tunnel in step four specifically includes: SSSS1: During shield tunneling, a high-precision total station with an accuracy class of no less than 1″ is used to conduct closed traverse surveying inside the tunnel. The high-precision total station is used as follows: Using the initial reference point underground as the starting point, a closed traverse is laid out along the tunnel axis. The side length of the traverse is controlled between 150 and 300 m, and the side length is appropriately shortened where the curve is not visible. Observation process: After the centering and leveling of each station is completed, the horizontal angle and distance of adjacent traverse points are observed. The horizontal angle is observed at least 4 times, and the distance is observed at least 3 times. Real-time progress: The measurement is carried out synchronously with the shield tunneling. The observation of one traverse point is completed every 5 rings of tunneling to ensure that the measurement is uninterrupted. SSSS2: Closed traverse surveying covers the entire tunneling section from the launching shaft L3 to the receiving shaft L2, and advances synchronously with the tunnel boring machine (TBM) excavation, with no measurement interruptions.

[0023] Specifically, step five of the traverse measurement includes calibrating the starting traverse edge outside the tunnel using gyroscope orientation before conducting the final closed traverse measurement inside the tunnel. Then, the control points outside the tunnel are used to verify the traverse near the well point. The gyroscope orientation results are compared with the closed traverse measurement results in step four. If the deviation exceeds ±5mm, the accuracy of the closed traverse needs to be adjusted. After the verification is completed, the surface and underground connection measurements are performed to determine the coordinates of the two points on the starting edge of the traverse inside the tunnel, thus completing the verification of the starting edge of the traverse inside the tunnel.

[0024] Specifically, step five includes: After the tunnel boring machine has advanced 200 meters, the first connection measurement is carried out, including gyro orientation, to establish a reliable starting point for subsequent tunneling. When the tunnel boring machine has tunneled to 1 / 3 of the breakthrough length, a second gyro-guided verification is performed. When the tunnel boring machine is about 150 meters away from the breakthrough surface, a third gyro orientation check is performed; If the tunnel length is ≥1.5km, the gyroscope orientation frequency needs to be increased.

[0025] Specifically, the requirements for setting up traverse points in step five are as follows: embedded traverse points should be set up at the base of the segments at 200m, 1 / 3 of the tunnel length, 150m from the receiving end, and other key ring numbers, with an accuracy of no less than ±1mm. These points serve as dual control points for gyro orientation and tunnel traverse. Other tunnel traverse points should not be located on the segment arch support. The traverse side length should be controlled between 150 and 300m to reduce the number of stations. The traverse side length should be appropriately shortened where curves are not visible. The gyroscope usage method is as follows: a gyro total station is used for calibration. Station preparation: The gyro total station is set up at the traverse points on the base of the segments, and centering and leveling are completed (for...). (Mean error ≤ 1mm, leveling error ≤ 2″), record instrument height and observation environment; Gyroscope initialization: Start the gyroscope total station and complete the north-finding operation (north-finding time not less than 10 minutes). After the north-finding accuracy stabilizes (deviation ≤ 3″), enter the observation mode; Orientation observation: Use the reversal point method to observe the azimuth of the traverse points. The number of observations should not be less than 3 rounds, and the number of reversal point observations in each round should not be less than 6; Record the azimuth results of each round; Accuracy verification: Compare the azimuth observed by the gyroscope with the azimuth measured by the closed traverse and calculate the deviation value; If the deviation exceeds ±5mm, the closed traverse measurement should be carried out again, and the coordinates of the traverse points should be adjusted.

[0026] Furthermore, step six specifically includes: F1: Before the tunnel is completed, the last in-tunnel guide point shall be set at the segment location no more than 150 meters from the exit end of the receiving shaft L2; F2: For the last traverse point inside the tunnel, simultaneously carry out the closed traverse measurement in step four and the gyroscope orientation verification in step five, ensuring that the positional error of the point does not exceed ±4mm.

[0027] Furthermore, the traverse measurement in step seven specifically includes: G1: After the tunnel is completed and the shield machine is lifted out of the receiving shaft L2, conduct traverse survey and leveling survey to verify the integrity of the data and guide subsequent shield section surveying work. G2: The traverse line is formed with the control points around the receiving well L2 as a reference, and the last traverse point in step six is ​​used to form the traverse line. The proposed connection point is determined, and the horizontal connection error and the vertical connection error are analyzed to provide experience for the subsequent connection measurement and traverse measurement of other sections.

[0028] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A measurement method for long-distance, small-diameter shield tunneling, characterized in that: The specific steps include the following: Step 1: Conduct a resurvey of the existing control points and densified control points outside the tunnel, including the horizontal and vertical control networks, and establish a measurement benchmark outside the tunnel; Step 2: Based on the external measurement benchmark established in Step 1, set up control points around the working shaft and perform periodic re-measurements. The periodic re-measurements include both horizontal and vertical measurements. The working shaft includes the launching shaft L3 and the receiving shaft L2. Step 3: Use multi-media coordinate transfer to complete the connection measurement between the surface and underground, and import the ground measurement benchmark into the underground. Then, use the inverted ruler method to introduce the elevation control points near the wellhead into the working shaft as the starting elevation for tunnel excavation, and check them regularly. Step 4: Simultaneously conduct closed traverse surveys within the tunnel throughout the entire shield tunneling process to monitor the accuracy of the tunneling process in real time. When the shield tunneling reaches 200m, set a tray point at the arch waist of the segment at 6m from the tunnel entrance and a control point on the bottom plate of the segment at 200m. Conduct connection measurements between the inside and outside of the tunnel and perform gyro orientation verification. Use these two points as the starting edge of the traverse within the tunnel. Perform a second gyro orientation verification when the tunnel reaches 1 / 3 of its length. Step 5: When there is 150m left in the tunnel, prepare to carry out the connection measurement and the traverse measurement inside the tunnel before the tunnel breakthrough. Perform gyro orientation verification on the control points outside the tunnel. Then, use the control points outside the tunnel to make a traverse to the near well point to ensure the accuracy of the starting edge of the traverse. Combine the traverse points of the segment layout to carry out gyro orientation verification and correct the measurement accuracy inside the tunnel. Step 6: Before the tunnel is completed, set up the end guide points within a preset distance from the L2 exit end of the receiving shaft and complete the calibration. After the closed guide is completed in the tunnel before the tunnel is completed, the receiving shaft will use the connection measurement to introduce the plane coordinates and elevation of the ground points into the receiving shaft, and complete the measurement of the actual coordinates of the steel ring of the receiving shaft portal. During the advancement process, the shield attitude is adjusted according to the actual coordinates of the receiving shaft until the tunnel is completed. Step 7: After the tunnel is completed and the shield machine is lifted out of the receiving shaft, selectively carry out traverse surveying to verify the accuracy of the breakthrough.

2. The measurement method for long-distance, small-diameter shield tunneling according to claim 1, characterized in that: The retesting and density-increasing deployment in step one specifically includes: S1: Use GNSS static measurement to remeasure the original control points outside the tunnel, with an observation time of no less than 60 minutes and baseline calculation accuracy controlled at ±2mm+1ppm; S2: Based on the remeasured control points outside the tunnel in S1, additional control points outside the tunnel are set up, with the positional error of the additional control points not exceeding ±3mm.

3. The measurement method for long-distance, small-diameter shield tunneling according to claim 1, characterized in that: The establishment and periodic re-measurement of surrounding control points in step two specifically include: SS1: Using the re-measured control points and densified points outside the tunnel, a total station is used to set up control points around the working shaft; SS2: Before each well-to-downhole connection measurement in step three, the control points around the working well must be remeasured. If the deviation of the remeasured point exceeds ±3mm, the control points around the well need to be re-established.

4. The measurement method for long-distance, small-diameter shield tunneling according to claim 1, characterized in that: The above-ground / downhole connection measurement in step three specifically includes: SSS1: At least three indium steel wires are suspended at the wellhead of the working well, and the diameter of the indium steel wires is ≤0.5mm, to serve as the coordinate transmission medium between the ground and the well. SSS2: A total station with an accuracy of no less than 1″ is used for both the surface and downhole operations to simultaneously observe the distance and angle of the indium wire. SSS3: Transmits the coordinates of ground control points to the downhole via indium wire observation data, thus establishing the initial measurement benchmark in the downhole.

5. The measurement method for long-distance, small-diameter shield tunneling according to claim 1, characterized in that: The closed traverse measurement inside the tunnel in step four specifically includes: SSSS1: During the tunnel boring machine excavation process, a total station with an accuracy class of not less than 1″ is used to carry out closed traverse surveying inside the tunnel; SSSS2: Closed traverse surveying covers the entire tunneling section from the launching shaft L3 to the receiving shaft L2, and advances synchronously with the tunnel boring machine (TBM) excavation, with no measurement interruptions.

6. The measurement method for long-distance, small-diameter shield tunneling according to claim 1, characterized in that: The traverse measurement in step five specifically includes calibrating the starting traverse edge outside the tunnel using gyroscope orientation before conducting the final closed traverse measurement inside the tunnel. Then, the control points outside the tunnel are used to verify the traverse near the well point. The gyroscope orientation results are compared with the closed traverse measurement results in step four. If the deviation exceeds ±5mm, the accuracy of the closed traverse needs to be adjusted. After the verification is completed, the surface and downhole connection measurement is performed to determine the coordinates of the two points of the starting edge of the traverse inside the tunnel, thus completing the verification of the starting edge of the traverse inside the tunnel.

7. The measurement method for long-distance, small-diameter shield tunneling according to claim 6, characterized in that: Step five includes: After the tunnel boring machine has advanced 200 meters, the first connection measurement is carried out, including gyro orientation, to establish a reliable starting point for subsequent tunneling. When the tunnel boring machine has tunneled to 1 / 3 of the breakthrough length, a second gyro-guided verification is performed. When the tunnel boring machine is about 150 meters away from the breakthrough surface, a third gyro orientation check is performed; If the tunnel length is ≥1.5km, the gyroscope orientation frequency needs to be increased.

8. The measurement method for long-distance, small-diameter shield tunneling according to claim 6, characterized in that: The requirements for setting up traverse points in step five are as follows: embedded traverse points should be set up at the bottom plate of the segments at 200m, 1 / 3 of the tunnel length, 150m from the receiving end, and other key ring numbers, with an accuracy of not less than ±1mm, serving as dual control points for gyro orientation and tunnel traverse; other tunnel traverse points should not be placed on the arch waist tray of the segments, and the side length of the traverse should be controlled between 150 and 300m to reduce the number of stations. The side length of the traverse should be appropriately shortened where the curve is not visible.

9. The measurement method for long-distance, small-diameter shield tunneling according to claim 1, characterized in that: Step six specifically includes: F1: Before the tunnel is completed, the last in-tunnel guide point shall be set up at a location no more than 150 meters from the exit end of the receiving shaft L2. F2: For the last traverse point inside the tunnel, simultaneously carry out the closed traverse measurement in step four and the gyroscope orientation verification in step five, ensuring that the positional error of the point does not exceed ±4mm.

10. The measurement method for long-distance, small-diameter shield tunneling according to claim 1, characterized in that: The traverse measurement in step seven specifically includes: G1: After the tunnel is completed and the shield machine is lifted out of the receiving shaft L2, conduct traverse surveying and leveling surveying to verify the integrity of the data and guide subsequent shield section surveying work. G2: The traverse line is formed with the control points around the receiving well L2 as a reference, and the last traverse point in step six is ​​used to form the traverse line. The proposed connection point is determined, and the horizontal connection error and the vertical connection error are analyzed to provide experience for the subsequent connection measurement and traverse measurement of other sections.

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