A method for determining the timing and sequence of cutting steel strands in flexible pipe segments of immersed tube tunnels

Abstract

The present invention is a method for determining the timing and order of cutting the steel strands of the flexible pipe segments of an immersed tube tunnel, including determining the timing of cutting the prestressed steel strands and determining the order of cutting the prestressed steel strands. The timing of cutting the prestressed steel strands satisfies the following conditions: the pipe segment is sunk and installed in place; the ballast concrete replaces the ballast water and the ballast water tank is removed; the backfilling of the pipe top of the pipe segment and the pipe top of the adjacent pipe segment is completed; there is no large load change process inside the pipe segment and on the pipe top; the settlement of the pipe segment has converged and there is no abnormal settlement change; the settlement rate of the pipe segment is less than 0.5 mm / d for more than 7 consecutive days. The order of cutting the cross-section of the prestressed steel strands is first the vehicle corridor and then the middle corridor. The order of cutting the longitudinal prestressed steel strands is determined in combination with the vertical deformation line type of the pipe segment. The present invention is conducive to judging the timing of cutting and rationally arranging the construction process; formulating a process with engineering operability to improve the operability of the method; and has achieved good operating results after engineering practice.

Description

Technical Field

[0001] The present invention relates to the technical field of immersed tube tunnel construction, and in particular to a method for determining the timing and sequence of shearing steel strands of flexible tube segments in an immersed tube tunnel. Background Art

[0002] Before floating and sinking the immersed tube segments, prestressed tendons are tensioned to connect the segments longitudinally as a single unit. This ensures that the compressive stress at the joints of each segment during construction is no less than the minimum compressive stress control requirement. 24 prestressed channels are arranged in the top plate and 22 in the bottom plate, with two reserved channels at the top and two at the bottom. A total of 5,450 prestressed channels are located in the 18 immersed tube segments, with 22 single-bundle 1.52cm holes at the top and 20 at the bottom, all using D140 casing. Once the immersed tubes are in place and the time for shearing is right, the temporary prestressed steel strands at the segment joints are sheared after design confirmation. The timing and order of strand shortening significantly impact engineering operations, but currently there is no clear method for determining this timing and order. Summary of the Invention

[0003] The present invention aims to solve the deficiencies of the prior art and provides a method for determining the timing and sequence of shearing steel strands of flexible pipe segments in immersed tube tunnels.

[0004] In order to achieve the above-mentioned purpose, the present invention adopts the following technical solutions:

[0005] A method for determining the timing and sequence of cutting steel strands of flexible pipe sections in an immersed tube tunnel includes determining the timing and sequence of cutting prestressed steel strands. The method includes determining the sequence of cutting cross-sectional steel strands and determining the sequence of cutting longitudinal steel strands.

[0006] The timing of shearing prestressed steel strands must meet the following conditions:

[0007] The pipe section is sunk and installed in place;

[0008] Ballast water replacement with ballast concrete and ballast water tank removal;

[0009] The backfilling of the pipe top of the pipe segment and the pipe tops of adjacent pipe segments is completed;

[0010] There is no large load change process inside the pipe section and on the pipe top;

[0011] The settlement of the pipe segment has converged, and there is no abnormal settlement change;

[0012] The settlement rate of the above-mentioned pipe sections was less than 0.5 mm / d for 7 consecutive days.

[0013] The order of cutting the cross-section steel strands of the prestressed steel strands is first the vehicle corridor and then the middle pipe corridor.

[0014] The steel strands of the two corridor cross sections are arranged symmetrically about the tunnel's central axis. The side of the corridor on one side that is closer to the central axis is the inner side, and the side that is farther away from the central axis is the outer side. There are three steel strands on the inner side and the inner side of the upper end of the corridor, and six steel strands on the outer side and the outer side of the lower end of the corridor, respectively.

[0015] The order of cutting the steel strands of the single-side corridor is as follows:

[0016] Sequence 1: the third steel strand on the inner side of the upper end;

[0017] Sequence 2: The fifth strand on the outside of the upper end;

[0018] Sequence three: the fifth strand on the outside of the lower end;

[0019] Sequence 4: the second strand on the inner side of the upper end;

[0020] Sequence 5: the third steel strand on the inner side of the lower end;

[0021] Sequence six: the fourth strand on the outside of the upper end;

[0022] Sequence seven: the fourth strand on the outside of the lower end;

[0023] Sequence 8: the first steel strand on the inner side of the upper end;

[0024] Sequence nine: the second steel strand on the inner side of the lower end;

[0025] Sequence 10: The third strand on the outside of the upper end;

[0026] Sequence 11: the third steel strand on the outside of the lower end;

[0027] Sequence 12: the first steel strand on the inner side of the lower end;

[0028] Sequence 13: the second strand on the outside of the upper end;

[0029] Sequence 14: the second strand on the outside of the lower end;

[0030] Sequence 15: the first strand on the outer side of the upper end;

[0031] Sequence 16: the first steel strand on the outside of the lower end;

[0032] The sixth outer steel strand at the upper end and the sixth outer steel strand at the lower end are not cut;

[0033] The symmetrical steel strands of the two corridors are cut simultaneously in sequence.

[0034] The steel strands in the cross section of the middle corridor are arranged symmetrically with respect to the central axis of the tunnel; there are three steel strands on one side of the upper end of the middle corridor from the inside out, and two steel strands on one side of the lower end of the middle corridor from the inside out;

[0035] The order of cutting the steel strands on one side of the middle corridor is as follows:

[0036] Sequence 1: the third strand from the top;

[0037] Sequence 2: the second strand at the top;

[0038] Sequence three: the second strand at the lower end;

[0039] Sequence 4: the first strand at the top;

[0040] Sequence 5: the first strand at the lower end;

[0041] The symmetrical steel strands on both sides of the central corridor are cut simultaneously in sequence.

[0042] The longitudinal cutting sequence of prestressed steel strands needs to be determined in combination with the vertical deformation line type of the pipe segment.

[0043] The methods for determining the vertical deformation line type of the pipe segment include:

[0044] P1. Establishment of measuring points: During the first outfitting period of the pipe segment, level elevation observation points are arranged at the beginning and end of each pipe segment, and all measuring points are required to be on the same horizontal plane;

[0045] P2. Elevation measurement of measuring points during outfitting period: establish temporary leveling elevation points, take the first leveling point of the pipe joint as the zero value point, and use a level to measure the elevations of other leveling points;

[0046] P3. Measurement of the plane position of measuring points during outfitting period: Use total station to measure the plane position of each measuring point and the plane coordinates of the first and last points of each segment;

[0047] For a straight pipe segment, the overall line shape of the pipe segment can be obtained by connecting the plane coordinate points of the first and last points of each segment, thereby determining the center axis of the pipe segment. Each measuring point is projected onto the center axis to obtain the distance between each measuring point on the axis.

[0048] For curved pipe segments, the overall curve line shape of the pipe segment can be obtained by connecting the plane coordinate points of the first and last points of each segment. Combined with the design curve requirements, the central axis of the pipe segment curve can be determined. Each measuring point is projected onto the central axis at right angles to the curve to obtain the distance between each measuring point on the axis.

[0049] P4. Initial leveling measurement after sinking: After the pipe section is sunk, the level elevation of each measuring point of the pipe section is measured with a stable and accurate 85 elevation leveling point to obtain the initial leveling value after the pipe section is sunk;

[0050] P5. Vertical deformation of the immersed tube upon completion of sinking and installation: Subtract the level elevation value of each measured value from the elevation measurement of the measuring point during the outfitting period to obtain the difference. Take the difference between the head and tail measuring points of the pipe section as the correction value. The correction value of the middle measuring point is obtained by linearly interpolating the head and tail correction values ​​according to the distance of each measuring point on the axis. Subtract the elevation correction value of each measuring point from the elevation difference of each measuring point to obtain the vertical deformation of the immersed tube upon completion of sinking and installation. Take the distance of each measuring point on the axis as the X-axis value and the vertical deformation value of the immersed tube upon completion of sinking and installation as the Y-axis value to obtain the vertical deformation curve of the immersed tube upon completion of sinking and installation.

[0051] P6. Leveling measurement before determining the cutting sequence: Before determining to cut the steel strands, use a stable and accurate 85-degree elevation leveling point to measure the level elevation of each measuring point of the pipe section to obtain the latest level elevation value of each measuring point of the immersed tube;

[0052] P7. Cumulative vertical deformation after installation of the immersed tube: Subtract the elevation of each measuring point after sinking from the latest elevation of each measuring point to obtain the cumulative vertical deformation value of each measuring point after installation. The distance between the measuring points on the axis is the X-axis value, and the vertical deformation value of the immersed tube when the sinking installation is completed is the Y-axis value to obtain the cumulative vertical deformation curve after installation of the immersed tube;

[0053] P8. Vertical deformation line type of immersed tube segment: The vertical deformation value of the immersed tube at each measuring point upon installation is added to the cumulative vertical deformation value after installation to obtain the relative change value of each measuring point. The distance between the measuring points on the axis is used as the X-axis value, and the relative change value of each measuring point is used as the Y-axis value to obtain the vertical deformation curve of the immersed tube segment;

[0054] P9. Linear classification of vertical deformation of immersed tubes: In the vertical deformation curve of the pipe segment, if the middle measuring point is above the deformation line connecting the two ends, it is an upward arch type; if the middle measuring point is below the deformation line connecting the two ends, it is a downward arch type; if the middle measuring point is above and below the deformation line connecting the two ends, and the deviation from the deformation line is greater than 2mm, it is an S-shaped mixed arch type; if the middle measuring point is on the deformation line connecting the two ends, and the deviation from the line is no more than 2mm, it is a linear type.

[0055] When the vertical deformation line of the pipe segment is an upward arch type, the longitudinal cutting order of the prestressed steel strand is: start from the maximum upward deflection and cut toward the side with less settlement. After the cutting of this side is completed, cut from the maximum upward deflection to the side with greater settlement.

[0056] When the vertical deformation line of the pipe segment is a downward arch type, the longitudinal cutting order of the prestressed steel strands is: cutting from the side with less settlement to the point with maximum deflection, not cutting at the point of maximum deflection, and then cutting from the side with greater settlement to the point with maximum deflection until all the strands are cut.

[0057] When the vertical deformation line type of the pipe segment is a mixed arch type, the longitudinal shearing sequence of the prestressed steel strands is:

[0058] First, determine the relative deviation of the upper and lower arches. If the deviation of the upper arch is greater, start shearing from the maximum upward deflection to the side with less settlement to the edge or the lowest point adjacent to the lower arch. Then, shear from the maximum upward deflection to the side with greater settlement to the edge or the lowest point adjacent to the lower arch. Finally, shear from the first and last sides to the lowest point of the lower arch. If the deviation of the lower arch is greater, shear from the side with less settlement or the arch top to the point with the maximum deflection at the arch bottom. Do not shear at the point of maximum deflection. Then, shear from the side with greater settlement or the arch top to the arch bottom. Finally, shear from the arch top to the edge.

[0059] When the vertical deformation line of the pipe segment is straight, the longitudinal cutting order of the prestressed steel strands is: cutting alternately from the middle segment to the first and last ends.

[0060] The beneficial effects of the present invention are as follows: the present invention is conducive to judging the shearing timing and reasonably arranging the construction process; formulating a process with engineering operability and improving the operability of the method; and through engineering practice, good operation results have been achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] Figure 1 Schematic diagram of the arrangement of prestressed steel strands in the cross section of the pipe segment of the present invention;

[0062] Figure 2 This is a planar position diagram of the later measuring points of eight pipe sections in a specific embodiment of the present invention;

[0063] Figure 3 This is a schematic diagram of the longitudinal shearing sequence of the prestressed steel strands when the vertical deformation line type of the pipe segment is an upward arch type;

[0064] Figure 4 This is a schematic diagram of the longitudinal shearing sequence of the prestressed steel strands when the vertical deformation line type of the pipe segment is a downward arch type;

[0065] The following is a detailed description of the embodiments of the present invention with reference to the accompanying drawings. DETAILED DESCRIPTION

[0066] The principles and features of the present invention are described below with reference to the accompanying drawings. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention. The following paragraphs describe the present invention in more detail by way of example with reference to the accompanying drawings. The advantages and features of the present invention will become more apparent from the following description. It should be noted that the drawings are all in a very simplified form and are not in exact proportions. They are only used to facilitate and clearly illustrate the purpose of the embodiments of the present invention.

[0067] It should be noted that when a component is referred to as being "fixed to" another component, it may be directly on the other component or there may also be a central component. When a component is considered to be "connected to" another component, it may be directly connected to the other component or there may also be a central component. When a component is considered to be "set on" another component, it may be directly set on the other component or there may also be a central component. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only.

[0068] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this invention pertains. The terms used in this specification of the present invention are for the purpose of describing specific embodiments only and are not intended to limit the present invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0069] The present invention will be further described below with reference to the accompanying drawings and examples:

[0070] A method for determining the timing and sequence of cutting steel strands of flexible pipe sections in an immersed tube tunnel includes determining the timing and sequence of cutting prestressed steel strands. The method includes determining the sequence of cutting cross-sectional steel strands and determining the sequence of cutting longitudinal steel strands.

[0071] The timing of shearing prestressed steel strands must meet the following conditions:

[0072] The pipe section is sunk and installed in place;

[0073] Ballast water replacement with ballast concrete and ballast water tank removal;

[0074] The backfilling of the pipe top of the pipe segment and the pipe tops of adjacent pipe segments is completed;

[0075] There is no large load change process inside the pipe section and on the pipe top;

[0076] The settlement of the pipe segment has converged, and there is no abnormal settlement change;

[0077] The settlement rate of the above-mentioned pipe sections was less than 0.5 mm / d for 7 consecutive days.

[0078] The order of cutting the cross-section steel strands of the prestressed steel strands is first the vehicle corridor and then the middle pipe corridor.

[0079] The steel strands of the two corridor cross sections are arranged symmetrically about the tunnel's central axis. The side of the corridor on one side that is closer to the central axis is the inner side, and the side that is farther away from the central axis is the outer side. There are three steel strands on the inner side and the inner side of the upper end of the corridor, and six steel strands on the outer side and the outer side of the lower end of the corridor, respectively.

[0080] The order of cutting the steel strands of the single-side corridor is as follows:

[0081] Sequence 1: the third steel strand on the inner side of the upper end;

[0082] Sequence 2: The fifth strand on the outside of the upper end;

[0083] Sequence three: the fifth strand on the outside of the lower end;

[0084] Sequence 4: the second strand on the inner side of the upper end;

[0085] Sequence 5: the third steel strand on the inner side of the lower end;

[0086] Sequence six: the fourth strand on the outside of the upper end;

[0087] Sequence seven: the fourth strand on the outside of the lower end;

[0088] Sequence 8: the first steel strand on the inner side of the upper end;

[0089] Sequence nine: the second steel strand on the inner side of the lower end;

[0090] Sequence 10: The third strand on the outside of the upper end;

[0091] Sequence 11: the third steel strand on the outside of the lower end;

[0092] Sequence 12: the first steel strand on the inner side of the lower end;

[0093] Sequence 13: the second strand on the outside of the upper end;

[0094] Sequence 14: the second strand on the outside of the lower end;

[0095] Sequence 15: the first strand on the outer side of the upper end;

[0096] Sequence 16: the first steel strand on the outside of the lower end;

[0097] The sixth outer steel strand at the upper end and the sixth outer steel strand at the lower end are not cut;

[0098] The symmetrical steel strands of the two corridors are cut simultaneously in sequence.

[0099] The steel strands in the cross section of the middle corridor are arranged symmetrically with respect to the central axis of the tunnel; there are three steel strands on one side of the upper end of the middle corridor from the inside out, and two steel strands on one side of the lower end of the middle corridor from the inside out;

[0100] The order of cutting the steel strands on one side of the middle corridor is as follows:

[0101] Sequence 1: the third strand from the top;

[0102] Sequence 2: the second strand at the top;

[0103] Sequence three: the second strand at the lower end;

[0104] Sequence 4: the first strand at the top;

[0105] Sequence 5: the first strand at the lower end;

[0106] The symmetrical steel strands on both sides of the central corridor are cut simultaneously in sequence.

[0107] like Figure 1 As shown, the steel strands in the cross section of the pipe segment are numbered as follows: the upper end steel strand is numbered with the first letter T, the lower end steel strand is numbered with the first letter B, and the numbering starts from the tunnel centerline and is numbered +1 towards both ends, and the numbering is symmetrical along the centerline.

[0108] The cutting order of the steel strands in the single-side corridor is: T6→T8→B7→T5→B5→T9→B8→T4→B4→T10→B9→B3→T11→B10→T12→B11;

[0109] T7 and B6 of the two corridors are not cut off to leave some symmetrical pre-stress for the concrete and to avoid large deformation between segments that may cause failure of the water-stop device between segments;

[0110] The cutting order of the steel strands on one side of the middle corridor is: T3→T2→B2→T1→B1.

[0111] The longitudinal cutting sequence of prestressed steel strands needs to be determined in combination with the vertical deformation line type of the pipe segment.

[0112] The methods for determining the vertical deformation line type of the pipe segment include:

[0113] P1. Establishment of measuring points: During the first outfitting period of pipe segments, level elevation observation points are arranged at the beginning and end of each pipe segment, such as Figure 2 As shown, all measuring points are required to be on the same horizontal plane;

[0114] P2. Elevation measurement of measuring points during outfitting period: establish temporary leveling elevation points, take the first leveling point of the pipe joint as the zero value point, and use a level to measure the elevations of other leveling points;

[0115] P3. Measurement of the plane position of measuring points during outfitting period: Use total station to measure the plane position of each measuring point and the plane coordinates of the first and last points of each segment;

[0116] For a straight pipe segment, the overall line shape of the pipe segment can be obtained by connecting the plane coordinate points of the first and last points of each segment, thereby determining the center axis of the pipe segment. Each measuring point is projected onto the center axis to obtain the distance between each measuring point on the axis.

[0117] For curved pipe segments, the overall curve line shape of the pipe segment can be obtained by connecting the plane coordinate points of the first and last points of each segment. Combined with the design curve requirements, the central axis of the pipe segment curve can be determined. Each measuring point is projected onto the central axis at right angles to the curve to obtain the distance between each measuring point on the axis.

[0118] P4. Initial leveling measurement after sinking: After the pipe section is sunk, the level elevation of each measuring point of the pipe section is measured with a stable and accurate 85 elevation leveling point to obtain the initial leveling value after the pipe section is sunk;

[0119] P5. Vertical deformation of the immersed tube upon completion of sinking and installation: Subtract the level elevation value of each measured value from the elevation measurement of the measuring point during the outfitting period to obtain the difference. Take the difference between the head and tail measuring points of the pipe section as the correction value. The correction value of the middle measuring point is obtained by linearly interpolating the head and tail correction values ​​according to the distance of each measuring point on the axis. Subtract the elevation correction value of each measuring point from the elevation difference of each measuring point to obtain the vertical deformation of the immersed tube upon completion of sinking and installation. Take the distance of each measuring point on the axis as the X-axis value and the vertical deformation value of the immersed tube upon completion of sinking and installation as the Y-axis value to obtain the vertical deformation curve of the immersed tube upon completion of sinking and installation.

[0120] P6. Leveling measurement before determining the cutting sequence: Before determining to cut the steel strands, use a stable and accurate 85-degree elevation leveling point to measure the level elevation of each measuring point of the pipe section to obtain the latest level elevation value of each measuring point of the immersed tube;

[0121] P7. Cumulative vertical deformation after installation of the immersed tube: Subtract the elevation of each measuring point after sinking from the latest elevation of each measuring point to obtain the cumulative vertical deformation value of each measuring point after installation. The distance between the measuring points on the axis is the X-axis value, and the vertical deformation value of the immersed tube when the sinking installation is completed is the Y-axis value to obtain the cumulative vertical deformation curve after installation of the immersed tube;

[0122] P8. Vertical deformation line type of immersed tube segment: The vertical deformation value of the immersed tube at each measuring point upon installation is added to the cumulative vertical deformation value after installation to obtain the relative change value of each measuring point. The distance between the measuring points on the axis is used as the X-axis value, and the relative change value of each measuring point is used as the Y-axis value to obtain the vertical deformation curve of the immersed tube segment;

[0123] P9. Linear classification of vertical deformation of immersed tubes: In the vertical deformation curve of the pipe segment, if the middle measuring point is above the deformation line connecting the two ends, it is an upward arch type; if the middle measuring point is below the deformation line connecting the two ends, it is a downward arch type; if the middle measuring point is above and below the deformation line connecting the two ends, and the deviation from the deformation line is greater than 2mm, it is an S-shaped mixed arch type; if the middle measuring point is on the deformation line connecting the two ends, and the deviation from the line is no more than 2mm, it is a linear type.

[0124] When the vertical deformation line of the pipe segment is an upward arch type, the longitudinal cutting order of the prestressed steel strand is: starting from the maximum upward deflection to the side with less settlement (higher), after the cutting of this side is completed, it is cut from the maximum upward deflection to the side with greater settlement (lower), such as Figure 3 As shown;

[0125] When the vertical deformation line of the pipe segment is a downward arch type, the longitudinal cutting order of the prestressed steel strands is: cutting from the side with less settlement (high) to the point with the maximum deflection, not cutting at the point with the maximum deflection, and then cutting from the side with greater settlement (lower) to the point with the maximum deflection until all the strands are cut. Figure 4 As shown;

[0126] When the vertical deformation line type of the pipe segment is a mixed arch type, the longitudinal shearing sequence of the prestressed steel strands is:

[0127] First, determine the relative deviation of the upper and lower arches. If the deviation of the upper arch is greater, start shearing from the maximum upward deflection to the side with less settlement to the edge or the lowest point adjacent to the lower arch. Then, shear from the maximum upward deflection to the side with greater settlement to the edge or the lowest point adjacent to the lower arch. Finally, shear from the first and last sides to the lowest point of the lower arch. If the deviation of the lower arch is greater, shear from the side with less settlement or the arch top to the point with the maximum deflection at the arch bottom. Do not shear at the point of maximum deflection. Then, shear from the side with greater settlement or the arch top to the arch bottom. Finally, shear from the arch top to the edge.

[0128] When the vertical deformation line of the pipe segment is straight, the longitudinal cutting order of the prestressed steel strand is: cutting alternately from the middle segment to the first and last ends. Figure 2 Taking the eight segments as an example, S1 to S8 in the figure are the labels of each segment, and the longitudinal cutting order of the prestressed steel strands is (S4-S5)→(S3-S4)→(S5-S6)→(S2-S3)→(S6-S7)→(S1-S2)→(S7-S8); (Sn-Sn+1) means cutting the prestressed steel strands between the nth segment and the n+1th segment.

[0129] The present invention is helpful for judging the cutting time and reasonably arranging the construction process; it formulates a process with engineering operability and improves the operability of the method; and it has achieved good operation results after engineering practice.

[0130] The present invention is described above by way of example in conjunction with the accompanying drawings. It is obvious that the specific implementation of the present invention is not limited to the above-mentioned method. As long as various improvements are made using the method concept and technical solution of the present invention, or they are directly applied to other occasions without improvement, they are all within the scope of protection of the present invention.

Claims

1. A method for determining the timing and sequence of shearing steel strands of flexible pipe segments in immersed tunnels, characterized in that: It includes determining the timing of cutting the prestressed steel strands and determining the order of cutting the prestressed steel strands. The determination of the order of cutting the prestressed steel strands includes determining the order of cutting the cross-section steel strands and determining the order of cutting the longitudinal steel strands. The timing of shearing the prestressed steel strands is determined by the following conditions: the pipe segments are sunk and installed in place; The ballast water is replaced by ballast concrete and the ballast water tank is removed; the backfill of the pipe top of the pipe segment and the pipe top of the adjacent pipe segment is completed; there is no large load change process inside the pipe segment and on the pipe top; the settlement of the pipe segment has converged and there is no abnormal settlement change; the settlement rate of the pipe segment is less than 0.5mm / d for more than 7 consecutive days; The order of cutting the prestressed steel strand cross section is first the vehicle corridor and then the middle pipe corridor; The longitudinal cutting sequence of prestressed steel strands needs to be determined in combination with the vertical deformation line type of the pipe segment.

2. The method for determining the timing and order of cutting the steel strands of the flexible pipe segments of an immersed tube tunnel according to claim 1 is characterized in that: The steel strands of the two corridor cross sections are arranged symmetrically about the tunnel's central axis. The side of the corridor on one side that is closer to the central axis is the inner side, and the side that is farther away from the central axis is the outer side. There are three steel strands on the inner side and the inner side of the upper end of the corridor, and six steel strands on the outer side and the outer side of the lower end of the corridor, respectively. The order of cutting the steel strands of the single-side corridor is as follows: Sequence 1: the third steel strand on the inner side of the upper end; Sequence 2: The fifth strand on the outside of the upper end; Sequence three: the fifth strand on the outside of the lower end; Sequence 4: the second strand on the inner side of the upper end; Sequence 5: the third steel strand on the inner side of the lower end; Sequence six: the fourth strand on the outside of the upper end; Sequence seven: the fourth strand on the outside of the lower end; Sequence eight: the first steel strand on the inner side of the upper end; Sequence nine: the second steel strand on the inner side of the lower end; Sequence 10: The third strand on the outside of the upper end; Sequence 11: the third steel strand on the outside of the lower end; Sequence 12: the first steel strand on the inner side of the lower end; Sequence 13: the second strand on the outside of the upper end; Sequence 14: the second steel strand on the outside of the lower end; Sequence 15: the first steel strand on the outside of the upper end; Sequence 16: the first steel strand on the outside of the lower end; The sixth outer steel strand at the upper end and the sixth outer steel strand at the lower end are not cut; The symmetrical steel strands of the two corridors are cut simultaneously in sequence.

3. The method for determining the timing and order of cutting the steel strands of the flexible pipe segments of an immersed tube tunnel according to claim 2, characterized in that: The steel strands in the cross section of the middle corridor are arranged symmetrically with respect to the central axis of the tunnel; there are three steel strands on one side of the upper end of the middle corridor from the inside out, and two steel strands on one side of the lower end of the middle corridor from the inside out; The order of cutting the steel strands on one side of the middle corridor is as follows: Sequence 1: the third strand from the top; Sequence 2: the second strand at the top; Sequence three: the second strand at the lower end; Sequence 4: the first strand at the top; Sequence 5: the first strand at the lower end; The symmetrical steel strands on both sides of the central corridor are cut simultaneously in sequence.

4. The method for determining the timing and order of cutting the steel strands of the flexible pipe segments of an immersed tube tunnel according to claim 3 is characterized in that: The methods for determining the vertical deformation line type of the pipe segment include: P1. Establishment of measuring points: During the first outfitting period of the pipe segment, level elevation observation points are arranged at the beginning and end of each pipe segment, and all measuring points are required to be on the same horizontal plane; P2. Elevation measurement of measuring points during outfitting period: establish temporary leveling elevation points, take the first leveling point of the pipe joint as the zero value point, and use the level to measure the elevations of other leveling points; P3. Measurement of the plane position of measuring points during outfitting period: Use total station to measure the plane position of each measuring point and the plane coordinates of the first and last points of each segment; For a straight pipe segment, the overall line shape of the pipe segment can be obtained by connecting the plane coordinate points of the first and last points of each segment, thereby determining the center axis of the pipe segment. Each measuring point is projected onto the center axis to obtain the distance between each measuring point on the axis. For curved pipe segments, the overall curve line shape of the pipe segment can be obtained by connecting the plane coordinate points of the first and last points of each segment. Combined with the design curve requirements, the central axis of the pipe segment curve can be determined. Each measuring point is projected onto the central axis at right angles to the curve to obtain the distance between each measuring point on the axis. P4. Initial leveling measurement after sinking: After the pipe segment is sunk, use a stable and accurate 85-degree leveling point to measure the level elevation of each measuring point of the pipe segment to obtain the initial leveling value after the pipe segment is sunk; P5. Vertical deformation of the immersed tube upon completion of sinking and installation: Subtract the level elevation value of each measured value from the elevation measurement of the measuring point during the outfitting period to obtain the difference. Take the difference between the head and tail measuring points of the pipe section as the correction value. The correction value of the middle measuring point is obtained by linearly interpolating the head and tail correction values ​​according to the distance of each measuring point on the axis. Subtract the elevation correction value of each measuring point from the elevation difference of each measuring point to obtain the vertical deformation of the immersed tube upon completion of sinking and installation. Take the distance of each measuring point on the axis as the X-axis value and the vertical deformation value of the immersed tube upon completion of sinking and installation as the Y-axis value to obtain the vertical deformation curve of the immersed tube upon completion of sinking and installation. P6. Leveling measurement before determining the cutting sequence: Before determining to cut the steel strands, use a stable and accurate 85-degree elevation leveling point to measure the level elevation of each measuring point of the pipe section to obtain the latest level elevation value of each measuring point of the immersed tube; P7. Cumulative vertical deformation after installation of the immersed tube: Subtract the elevation of each measuring point after sinking from the latest elevation of each measuring point to obtain the cumulative vertical deformation value of each measuring point after installation. The distance between the measuring points on the axis is the X-axis value, and the vertical deformation value of the immersed tube when the sinking installation is completed is the Y-axis value to obtain the cumulative vertical deformation curve after installation of the immersed tube; P8. Vertical deformation line type of immersed tube segment: The vertical deformation value of the immersed tube at each measuring point upon installation is added to the cumulative vertical deformation value after installation to obtain the relative change value of each measuring point. The distance between the measuring points on the axis is used as the X-axis value, and the relative change value of each measuring point is used as the Y-axis value to obtain the vertical deformation curve of the immersed tube segment; P9. Linear classification of vertical deformation of immersed tubes: In the vertical deformation curve of the pipe segment, if the middle measuring point is above the deformation line connecting the two ends, it is an upward arch type; if the middle measuring point is below the deformation line connecting the two ends, it is a downward arch type; if the middle measuring point is above and below the deformation line connecting the two ends, and the deviation from the deformation line is greater than 2mm, it is an S-shaped mixed arch type; if the middle measuring point is on the deformation line connecting the two ends, and the deviation from the line is no more than 2mm, it is a linear type.

5. The method for determining the timing and order of cutting the steel strands of the flexible pipe segments of an immersed tube tunnel according to claim 4, characterized in that: When the vertical deformation line of the pipe segment is an upward arch type, the longitudinal cutting order of the prestressed steel strand is: start from the maximum upward deflection and cut toward the side with less settlement. After the cutting of this side is completed, cut from the maximum upward deflection to the side with greater settlement.

6. The method for determining the timing and order of cutting the steel strands of the flexible pipe segments of an immersed tube tunnel according to claim 5, characterized in that: When the vertical deformation line of the pipe segment is a downward arch type, the longitudinal cutting order of the prestressed steel strands is: cutting from the side with less settlement to the point with maximum deflection, not cutting at the point of maximum deflection, and then cutting from the side with greater settlement to the point with maximum deflection until all the strands are cut.

7. The method for determining the timing and order of cutting the steel strands of the flexible pipe segments of an immersed tube tunnel according to claim 6, characterized in that: When the vertical deformation line type of the pipe segment is a mixed arch type, the longitudinal shearing sequence of the prestressed steel strands is: First, determine the relative deviation of the upper and lower arches. If the deviation of the upper arch is greater, start shearing from the maximum upward deflection to the side with less settlement to the edge or the lowest point adjacent to the lower arch. Then, shear from the maximum upward deflection to the side with greater settlement to the edge or the lowest point adjacent to the lower arch. Finally, shear from the first and last sides to the lowest point of the lower arch. If the deviation of the lower arch is greater, shear from the side with less settlement or the arch top to the point with the maximum deflection at the arch bottom. Do not shear at the point of maximum deflection. Then, shear from the side with greater settlement or the arch top to the arch bottom. Finally, shear from the arch top to the edge. When the vertical deformation line of the pipe segment is straight, the longitudinal cutting order of the prestressed steel strands is: cutting alternately from the middle segment to the first and last ends.

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