Self-tightening reinforcement structure and reinforcement method for shield tunnel structure deformation

Abstract

The present invention discloses a self-tightening reinforcement structure and method for shield tunnel structural deformation. Anchors are provided on the basis of the original segments and are passed through steel bar bundles for tensioning and anchoring. After the segments are assembled, the steel bar bundles are passed through the reserved holes of the segments and connected to the anchors, the prestressed steel bars are tensioned, and then the anchors are tightened to complete the initial reinforcement. As the tunnel is used, under the influence of comprehensive factors such as deadweight, track vibration, and settlement, the segments undergo displacement and deformation. At this time, the anchors located in the adjacent blocks are tightened after being tensioned, so that the width of the cracks between the segments is reduced. The higher the degree of cracking on one side of the segment, the more obvious the self-tightening effect is, thereby achieving self-tightening reinforcement of the segments. The present invention innovatively uses specially designed anchors to achieve self-tightening of the segments; quickly forms an effective self-anchored prestressed reinforcement structure, effectively suppresses deformation, ensures the structural safety and ovality requirements of the shield tunnel, and enables the reinforced shield tunnel to have normal traffic capacity.

Description

Technical Field

[0001] The invention relates to the technical field of underground buildings, in particular to a self-tightening reinforcement structure for shield tunnel structure deformation. Background Art

[0002] The vertical and horizontal earth pressures in the tunnel are constantly changing due to overloading and unloading of the soil around the tunnel, and eventually the tunnel structure exceeds the limit of convergence deformation.

[0003] The over-limit convergence deformation of the shield tunnel structure will cause secondary damage to the shield tunnel structure, such as segment cracks, water leakage, etc. Further, it will reduce the bearing capacity of the shield tunnel structure, forming a vicious cycle.

[0004] During the service of the shield tunnel, the segments are fastened once by bolts, and are deformed due to the coupling of soil pressure and track vibration for a long time. At the same time, the bearing capacity of the bolts is destroyed and the deformation continues to increase. In order to ensure the operation of the subway and the safety of passengers' lives and property, it is urgent to find a reinforcement method to reinforce the tunnel segments. Summary of the invention

[0005] In view of the above technical problems, the purpose of the present invention is to propose a prestressed device for preventing and promptly repairing the displacement of the tunnel segments caused by the continuous changes in the vertical and horizontal earth pressures of the tunnel caused by the overloading and unloading of the soil around the tunnel, and ultimately the excessive convergence deformation of the tunnel structure.

[0006] In order to achieve the above technical objectives, the present invention adopts the following technical means:

[0007] A self-tightening reinforcement structure for deformation of a shield tunnel structure, wherein the shield tunnel comprises a capping block segment located at an upper portion, a standard block segment located at a lower portion of the tunnel, and an adjacent block segment connected between the capping block segment and the standard block segment, wherein a first through hole is provided in the adjacent block segment, wherein the first through hole extends from the capping block segment to the standard block segment in the adjacent block segment, and wherein the first through hole is provided with:

[0008] The external anchor group comprises a first external anchor group and a second external anchor group, wherein the first external anchor group is arranged in the first through hole near one end of the standard segment, and the second external anchor group is arranged in the first through hole near one end of the capping block segment; the external anchor group comprises a plurality of external anchors, the plurality of external anchors are arranged in sequence along the axis direction of the first through hole, each external anchor is provided with a second through hole, the second through hole has a large diameter hole end and a small diameter hole end; the large diameter hole end on the first external anchor is arranged near the standard segment, and the large diameter hole end on the second external anchor is arranged near the capping block segment;

[0009] A first inner anchor is initially arranged in the second through hole of an outer anchor closest to the standard block segment in the first outer anchor group, and a third through hole is arranged on the first inner anchor;

[0010] A second inner anchor is initially arranged in the second through hole of an outer anchor in the second outer anchor group that is closest to the capping block segment, and a fourth through hole is arranged on the second inner anchor;

[0011] A prestressed steel bar is arranged in the first through hole, one end of which is passed through the third through hole of the first inner anchor and fixed with the first inner anchor, then passed through the designated position of the standard block segment and fixed with bolts; the other end of which is passed through the fourth through hole of the second inner anchor and fixed with the second inner anchor, then passed through the designated position of the capping block segment and fixed with bolts;

[0012] When cracks occur on the contact surface of the adjacent block segment, the prestressed steel bars are tensioned and move with the inner anchor. The inner anchor moves forward along the arrangement direction of multiple outer anchors in the outer anchor group, from one outer anchor to the next. The stress in the prestressed steel bar section between the first inner anchor and the second inner anchor increases to limit the width of the crack on that side of the adjacent block segment.

[0013] The first through hole is located on the contact surface between the adjacent block segment and the bottom block and is arranged close to the inner wall of the adjacent block segment. The first through hole is located on the contact surface between the adjacent block segment and the standard fast segment and is arranged close to the outer wall of the adjacent block segment.

[0014] The contact surface between the inner anchor and the outer anchor is a curved surface.

[0015] A notch is provided on the outer wall of the inner anchor, and a large-diameter hole end is provided at the bottom end of the inner anchor, and a one-way tightening annular tightening mechanism is provided on the large-diameter hole end;

[0016] The upper end of the inner anchor is a small diameter hole end;

[0017] The outer side of the inner anchor is curved, with a pointed head and a protruding waist. The upper curve radius of the waist is large, while the lower curve radius is small.

[0018] The outer side of the outer anchor is a cylinder, and the inner side is a curved surface, and the shape of the curved surface is complementary to the shape of the outer wall of the inner anchor;

[0019] When the inner anchor moves forward relative to the outer anchor, the two sides of the inner anchor cutout are moved closer by the force of the outer anchor, and can move forward smoothly;

[0020] When the inner anchor moves backward relative to the outer anchor, it is constrained by the annular tightening mechanism at the bottom, and the diameter of the inner anchor after extrusion deformation will no longer expand, thereby ensuring the relative fixation between the prestressed steel bar and the inner anchor.

[0021] The annular contraction mechanism is composed of an inner and outer ring, the outer side of the inner ring is provided with a bayonet, and the inner side of the outer ring is provided with equidistant grooves; when the inner and outer rings move, the bayonet moves along the grooves of the outer ring, stops moving and is fixed in position, and the annular contraction mechanism is tightened.

[0022] The inner anchor and the outer anchor are both made of steel.

[0023] The prestressed steel bar is connected to the inner anchor. When the prestressed steel bar moves relative to the small-diameter hole end at the upper end of the inner anchor, the prestressed steel bar drives the inner anchor to move relative to the outer anchor. The two sides of the inner anchor cutout are brought closer due to the force of the outer anchor. At the same time, the bottom of the inner anchor shrinks, and the friction resistance it encounters increases and it is gradually tightened. When the prestressed steel bar moves relative to the large-diameter hole end at the lower end of the inner anchor, the shape of the inner anchor remains unchanged, and the prestressed steel bar moves relative to the anchor.

[0024] The present invention further discloses a method for reinforcing the self-tightening reinforcement structure of the shield tunnel structure deformation, comprising the following steps:

[0025] S1. Tension the prestressed steel bar at one end of the standard block to reach the specified tension force, and adjust the inner anchor to contact with the outer anchor;

[0026] S2, pass the prestressed steel bar through the original anchor position of the standard block segment, tension it to the specified prestressing force and then fix it with bolts;

[0027] S3. During normal use, the joints at both ends of the adjacent segments are subjected to the tensile force of the prestressed steel bars to limit deformation;

[0028] S4. When the cracking effect continues to increase, the crack deformation causes the prestressed steel bars to be tensioned. At this time, the prestressed steel bars and the inner anchor move relative to the outer anchor at the same time, and the inner anchor enters the next outer anchor; the stress of the prestressed steel bars behind the inner anchor increases to limit the crack width on this side of the adjacent block segment.

[0029] Stress strain gauges are attached to the prestressed steel bars at the front and rear ends of the inner anchor. When the stress strain gauges sense that the forces on the prestressed steel bars on both sides of the inner anchor are different, they will feedback to the management department. Workers will tension and fix the prestressed steel bars on the side with smaller stress, i.e. the front end of the movable inner anchor, to increase the overall strength and reduce the width of the crack.

[0030] Beneficial effects:

[0031] When the pipe segments have been in service for a long time, due to multiple factors such as the deadweight load of the soil and the coupling effect of the train track vibration, the pipe segments may deform or crack. Thanks to the solution of the present invention, the pipe segments will have the following protection measures:

[0032] First: Compared with the bolt connection of the traditional scheme, this scheme adopts prestressed steel bar connection, which improves its crack resistance;

[0033] Second: When cracks occur on the contact surface of the pipe segment, the steel bar is tensioned and moves with the inner anchor. The inner anchor moves forward along the outer anchor relatively, from one outer anchor to the next. Due to the design characteristics of the inner and outer anchors, the contact effect between the inner anchor and the steel bar is stronger, and there is greater friction between the surfaces of the two. At the same time, the steel bars on the front and rear sides of the inner anchor can make the internal forces of the front and rear steel bars different due to the gentle friction resistance. The internal force of the steel bar in front of the inner anchor is small, and the internal force at the rear is large. The steel bar with large internal force can strengthen the effect between the pipe segments, so that after a certain deformation occurs on the contact surface of one end of the pipe segment, the force at the other end is strengthened, thereby improving the overall strength;

[0034] Third: stress strain gauges can be attached to the steel bars at the front and rear ends of the inner anchor respectively. This device is small in size and sensitive. When it receives different stress magnitudes on a steel bar, it can be used as a signal that maintenance is required, making it convenient for maintenance personnel to repair the pipe segments in a timely manner.

[0035] Fourth: The opening position of the first through hole is specially designed, and it takes into account the cracking and deformation characteristics of the pipe segment during long-term use. The contact surface between the adjacent block pipe segment and the bottom block has small cracks on the upper part and large cracks on the lower part, so when setting the opening position on this contact surface, the opening position is lower, but the minimum thickness of the concrete protective layer needs to be guaranteed; on the contrary, the contact surface between the adjacent block and the standard block has large cracks on the upper part (or the outer side) and small cracks on the lower part (inside), so the opening on the contact surface should be close to the outside. Next: After the opening position is determined, the centers of the opening circles of the two contact surfaces can be smoothly connected with multiple arcs.

[0036] Finally, the present invention can delay the cracking deformation of the pipe segment, improve its bearing capacity, and increase the life of the tunnel pipe segment. At the same time, the stress and strain detection device can effectively monitor and timely control. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 : The position of the embedded reinforcement tendons in the adjacent segments;

[0038] Figure 2 : The opening positions at both ends of the adjacent block segments;

[0039] Figure 3 : Plan view of the opening positions on the contact surface between the adjacent block segment and the standard block segment;

[0040] Figure 4 : Plan view of the opening positions on the contact surface between the adjacent block segments and the capping block segments;

[0041] Figure 5 : The internal and external combined structure of the anchor;

[0042] Figure 6 : The inside of the anchor, i.e. the inner anchor part;

[0043] Among them, 1 is the head of the inner anchor; 2 is the rectangular cutout on the inner anchor; 3 is the protrusion at the waist of the inner anchor; 4 is the bottom of the inner anchor, which is provided with an annular tightening device;

[0044] Figure 7 : The inside of the anchor, i.e. the outer anchor part;

[0045] Figure 8 : The position of the external anchorage set in the adjacent block segment;

[0046] Fig. 9 : The position of the external anchorage near the standard fast position set in the adjacent block segment;

[0047] Fig.10 : The position of the external anchorage near the capping block set in the adjacent block segment;

[0048] Fig.11 : Cracking and deformation characteristics of pipe segments during long-term use. DETAILED DESCRIPTION

[0049] The technical solution of the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0050] like Figure 1 to Figure 10 As shown, a self-tightening reinforcement structure for deformation of a shield tunnel structure, the shield tunnel comprises a capping block segment located at the upper part, a standard block segment located at the lower part of the tunnel, and an adjacent block segment connected between the capping block segment and the standard block segment, wherein a first through hole is opened in the adjacent block segment, the first through hole is extended from the capping block segment to the standard block segment in the adjacent block segment, and the first through hole is provided with:

[0051] The external anchor group comprises a first external anchor group and a second external anchor group, wherein the first external anchor group is arranged in the first through hole near one end of the standard segment, and the second external anchor group is arranged in the first through hole near one end of the capping block segment; the external anchor group comprises a plurality of external anchors, the plurality of external anchors are arranged in sequence along the axis direction of the first through hole, each external anchor is provided with a second through hole, the second through hole has a large diameter hole end and a small diameter hole end; the large diameter hole end on the first external anchor is arranged near the standard segment, and the large diameter hole end on the second external anchor is arranged near the capping block segment;

[0052] A first inner anchor is initially arranged in the second through hole of an outer anchor closest to the standard block segment in the first outer anchor group, and a third through hole is arranged on the first inner anchor;

[0053] A second inner anchor is initially arranged in the second through hole of an outer anchor in the second outer anchor group that is closest to the capping block segment, and a fourth through hole is arranged on the second inner anchor;

[0054] A prestressed steel bar is arranged in the first through hole, one end of which is passed through the third through hole of the first inner anchor and fixed with the first inner anchor, then passed through the designated position of the standard block segment and fixed with bolts; the other end of which is passed through the fourth through hole of the second inner anchor and fixed with the second inner anchor, then passed through the designated position of the capping block segment and fixed with bolts;

[0055] When cracks occur on the contact surface of the adjacent block segment, the prestressed steel bars are tensioned and move with the inner anchor. The inner anchor moves forward along the arrangement direction of multiple outer anchors in the outer anchor group, from one outer anchor to the next. The stress in the prestressed steel bar section between the first inner anchor and the second inner anchor increases to limit the width of the crack on that side of the adjacent block segment.

[0056] like Fig.11 As shown, the anchor is installed in the adjacent block segment, and the opening position of the first through hole is determined in the adjacent block. This opening trajectory is specially designed, and it takes into account the cracking and deformation characteristics of the segment during long-term use.

[0057] The contact surface between the adjacent block segment and the bottom block has small cracks on the upper part and large cracks on the lower part, so when setting the hole position on this contact surface, the hole position should be lower, but the minimum thickness of the concrete protective layer needs to be guaranteed; on the contrary, the contact surface between the adjacent block and the standard block has large cracks on the upper part (or the outer side) and small cracks on the lower part (inside), so the hole on the contact surface should be closer to the outside. Next: After the hole position is determined, the centers of the two contact surface holes can be smoothly connected with multiple arcs.

[0058] A total of two openings with the above-mentioned trajectories are made in the pipe segment.

[0059] The anchor of the present invention can be made of common anchor materials such as steel, which is convenient for processing. When the pipe segment is prefabricated in the factory, the external anchor is fixed inside the pipe segment. Specific fixing position: First, on the trajectory line mentioned above, while ensuring that the anchor and the pipe segment have sufficient pull-out resistance, in order to improve the effect of this process, a steel bar can be welded between the anchor and the pipe segment.

[0060] For the anchor: the anchor is divided into two parts, inner and outer, respectively called inner anchor and outer anchor. For both anchors, there are upper and lower parts. The inner anchor has a small upper part and a large lower part. There is an opening inside it. The size of the opening is the same as the outer diameter of the prestressed steel bar. The size of the opening can be selected according to the actual situation. The lower part of the inner anchor is provided with a rectangular opening along the vertical direction of the bottom surface, and there is an annular tightening device underneath. The two parts are a whole. The purpose is to ensure that the prestressed steel bar can pass through conveniently. At the same time, during use, when the inner anchor moves forward relative to the outer anchor, the lower part of the inner anchor is provided with an opening, and the two petals of the lower part will approach each other. At this time, the annular tightening device at the bottom plays a role. Once it shrinks, it will not open again. In this way, the inner anchor can be used in actual use. Because it receives a forward force, the two petals of the lower part of the inner anchor are close and locked, which strengthens the contact with the steel bar. At the same time, the outer surface of the inner anchor and the inner surface of the outer anchor are both curved surface designs. The two curved surfaces complement each other. When spliced ​​normally, the inner and outer parts are in uniform contact. The curved surface design is considered in this way. Take the inner anchor as an example: the basic characteristics of the anchor are that the waist is thick, the head and the foot are small, and the head, waist and foot are composed of three curves. The head curve is concave inward, the waist is convex outward, and the foot is concave; at the same time, the concave degree of the foot is greater than that of the head. In this way, when the inner anchor moves forward relative to the outer anchor, that is, when it moves toward the head, it can move forward smoothly because the head is relatively flat and the steel has a certain deformation capacity. The waist and foot will be tightened due to the incision, so it can also move forward smoothly. In this way, the inner anchor can move forward smoothly along the outer anchor. On the contrary, if the inner anchor is subjected to a backward force, due to the large degree of concave of the foot curve, the angle between the contact surface of the inner and outer anchors and the center axis of the anchor is close to ninety degrees, and its backward movement is hindered.

[0061] There are two first through holes, and two sets of external anchors and two internal anchors are installed in each first through hole, with the front end of the external anchor facing the outside of the segment and the head of the internal anchor facing the outside of the segment. Each set of external anchors is continuously arranged by three sections of external anchors, which can ensure that the internal anchors move forward continuously in the external anchors.

[0062] When making adjacent segments, not only are the inner and outer anchors fixed, the inner anchor is fixed in the innermost outer anchor of each group of outer anchors, and the prestressed steel bars are passed through the anchors first. In order to facilitate the later pouring of concrete on the segments, the steel bars can be painted with oil and waterproof materials on the surface. At the same time, mortar and other materials can be poured into the gaps between the internal openings and the steel bars to reduce the friction between the steel bars and the segments.

[0063] In the actual installation process, after the standard block segments are installed, the adjacent block segments should be installed. First, the prestressed steel bars passing through the lower part of the adjacent block segments should be passed through the holes in the standard block segments. After the adjacent block segments are installed, the capping block segments should be installed in the same way. After the whole ring is installed, it is tensioned with a tensioning device and fixed to the adjacent two side segments of the adjacent block with bolts and other traditional methods.

[0064] Working condition of anchors: When the segments have been in service for a long time, the segments may be deformed or cracks may begin to form between the segments due to multiple factors such as the deadweight load of the soil and the coupling effect of train track vibration. Thanks to the invention of this solution, the segments will have the following protection measures:

[0065] First: Compared with the bolt connection of the traditional scheme, this scheme adopts prestressed steel bar connection, which improves its crack resistance;

[0066] Second: When cracks occur on the contact surface of the pipe segment, the steel bar is tensioned and moves with the inner anchor. The inner anchor moves forward along the outer anchor relatively, from one outer anchor to the next. Due to the design characteristics of the inner and outer anchors, the contact between the inner anchor and the steel bar is stronger, and there is greater friction between the surfaces of the two. At the same time, the steel bars on the front and rear sides of the inner anchor can make the internal forces of the front and rear steel bars different due to the gentle friction resistance. The internal force of the steel bar in front of the inner anchor is small, and the internal force at the rear is large. The steel bar with large internal force can strengthen the effect between the pipe segments, so that after a certain deformation occurs on the contact surface of one end of the pipe segment, the force on the other end is strengthened, thereby improving the overall strength;

[0067] Third: stress strain gauges can be attached to the steel bars at the front and rear ends of the inner anchor respectively. This device is small in size and sensitive. When it receives different stress magnitudes on a steel bar, it can be used as a signal that maintenance is required, making it convenient for maintenance personnel to repair the pipe segments in a timely manner.

[0068] It is specially noted that each time the inner anchor takes effect, generally only the inner anchor at one end will move forward along the outer anchor to tighten the steel bar, while the inner anchor at the other end has not moved forward along the outer anchor, so the contact between the inner anchor and the steel bar will not be very large. At this time, the steel bar can still move in the inner anchor. Only when the inner anchor moves forward and causes the inner anchor foot to lock, will the inner anchor and the steel bar have a greater force. In other words, two anchors are built into the pipe segment to respectively protect the contact surface between the pipe segments close to it. The section that deforms first has the anchor that takes effect first.

[0069] The highlights and innovations of the present invention are mainly: prestressed steel bars replace the original bolt reinforcement method; the hole position is determined according to the cracking characteristics; special anchors achieve temporary self-tightening; strain gauges are used as a method of detecting cracks in the pipe segments; in addition to modifying the adjacent blocks, this solution does not change the capping blocks and standard blocks, and all positions where the steel bars pass through are reinforced with bolts, which reduces the initial strength drop of the pipe segments.

[0070] The present invention proposes to use prestressed steel bars for real-time adjustment. For a proposed shield tunnel, the segment structure designed by the scheme is adopted, and the specific steps are as follows:

[0071] 1) When prefabricating segments in the factory, the adjacent segments are Figure 1 and Figure 2 and Figure 3 way of opening the hole.

[0072] 2) Fix the external anchors in the opening at a certain distance, such as Figure 8 As shown in Figure 2, the specific design positions of the two groups of anchors are as follows: Fig. 9 and Fig.10 As shown, fix the inner anchor to the steel bar and pass it through the outer anchor. Figure 5 shown.

[0073] 3) At the construction site, install the temporary blocks and capping blocks in sequence.

[0074] 4) Fix one end with bolts in the capping block adjacent to the adjacent block.

[0075] 5) Tension the prestressed steel bars to reach the specified tensioning force, and at the same time make the inner mold contact with the outer mold.

[0076] 6) Pass the steel bar bundle through the designated position of the standard block and secure it with bolts.

[0077] 7) During normal use, the two ends of the adjacent blocks are unsealed and subjected to the tensile force of the prestressed steel bars to limit deformation.

[0078] 8) When the cracking effect continues to increase, the crack deformation causes the steel bar to be tensioned. At this time, the steel bar and the inner anchor move relative to the outer anchor at the same time, and the inner anchor enters the next outer anchor; the stress of the steel bar behind the inner anchor increases to limit the crack width on this side of the segment.

[0079] 9) When the stress strain gauge senses that the stress on the steel bars on both sides of the anchor is different, it will feedback to the management department. The workers only need to tension and fix the steel bars on the side with smaller stress to improve the overall strength and reduce the crack width. The steel bar bundle on the other side has achieved stable shrinkage under the tension of the crack thanks to the anchor designed by the present invention.

Claims

1. A self-tightening reinforcement structure for deformation of a shield tunnel structure, wherein the shield tunnel comprises a capping segment located at the upper part, a standard segment located at the lower part of the tunnel, and an adjacent segment connected between the capping segment and the standard segment, characterized in that: A first through hole is provided in the adjacent block segment, and the first through hole is extended from the capping block segment to the standard block segment in the adjacent block segment, and the first through hole is provided with: an external anchor group, including a first external anchor group and a second external anchor group, wherein the first external anchor group is arranged in the first through hole adjacent to one end of the standard segment, and the second external anchor group is arranged in the first through hole adjacent to one end of the capping block segment; the external anchor group includes a plurality of external anchors, and the plurality of external anchors are arranged in sequence along the axis direction of the first through hole, and each external anchor is provided with a second through hole, and the second through hole has a large diameter hole end and a small diameter hole end; the large diameter hole end on the first external anchor is arranged adjacent to the standard block segment, and the large diameter hole end on the second external anchor is arranged adjacent to the capping block segment; A first inner anchor is initially arranged in the second through hole of an outer anchor closest to the standard block segment in the first outer anchor group, and a third through hole is arranged on the first inner anchor; A second inner anchor is initially arranged in the second through hole of an outer anchor closest to the capping block segment in the second outer anchor group, and a fourth through hole is arranged on the second inner anchor; A prestressed steel bar is arranged in the first through hole, one end of which is passed through the third through hole of the first inner anchor and fixed with the first inner anchor, then passed through the designated position of the standard block segment and fixed with bolts; the other end of which is passed through the fourth through hole of the second inner anchor and fixed with the second inner anchor, then passed through the designated position of the capping block segment and fixed with bolts; When cracks occur on the contact surface of the adjacent block segment, the prestressed steel bar is tensioned, and the first inner anchor and the second inner anchor are moved, and the first inner anchor and the second inner anchor move forward along the arrangement direction of the multiple outer anchors in the outer anchor group, and move from one outer anchor to the next outer anchor. The stress of the prestressed steel bar segment between the first inner anchor and the second inner anchor increases to limit the width of the crack on the side of the adjacent block segment; The opening position of the first through hole located on the contact surface between the adjacent block segment and the bottom sealing block is arranged close to the inner wall of the adjacent block segment, and the opening position of the first through hole located on the contact surface between the adjacent block segment and the standard fast segment is arranged close to the outer wall of the adjacent block segment; The outer walls of the first inner anchor and the second inner anchor are provided with cutouts, the bottom ends of the first inner anchor and the second inner anchor have large-diameter hole ends, and the large-diameter hole ends are provided with a one-way tightening annular tightening mechanism; The upper ends of the first inner anchor and the second inner anchor are small diameter hole ends; The outer side surfaces of the first inner anchor and the second inner anchor are curved, with a pointed head and a protruding waist, a large curve radius on the upper side of the waist and a small curve radius on the lower side, the outer side of the outer anchor is a cylinder, and the inner side is a curved surface, and the shape of the curved surface is complementary to the shape of the outer wall of the first inner anchor and the second inner anchor; When the first inner anchor and the second inner anchor move forward relative to the outer anchor, the two sides of the cutouts of the first inner anchor and the second inner anchor are moved closer by the force of the outer anchor, and can move forward smoothly; When the first inner anchor and the second inner anchor move backward relative to the outer anchor, they are constrained by the bottom annular tightening mechanism, and the diameters of the first inner anchor and the second inner anchor after extrusion deformation will not expand any further, thereby ensuring that the prestressed steel bar is relatively fixed to the first inner anchor and the second inner anchor; The annular tightening mechanism is composed of an inner and outer ring, the outer side of the inner ring is provided with a bayonet, and the inner side of the outer ring is provided with equidistant grooves; when the inner and outer rings move, the bayonet moves along the outer ring grooves, stops moving and is fixed in position, and the annular tightening mechanism is tightened; The prestressed steel bar is connected to the first inner anchor and the second inner anchor. When the prestressed steel bar moves relative to the small-diameter hole end at the upper end of the first inner anchor and the second inner anchor, the prestressed steel bar drives the first inner anchor and the second inner anchor to move relative to the outer anchor. The two sides of the cutouts of the first inner anchor and the second inner anchor are brought closer due to the force of the outer anchor. At the same time, the bottom of the first inner anchor and the second inner anchor shrinks, and the friction resistance they encounter increases and they are gradually tightened. When the prestressed steel bar moves relative to the large-diameter hole end at the lower end of the first inner anchor and the second inner anchor, the shapes of the first inner anchor and the second inner anchor remain unchanged, and the prestressed steel bar moves relative to the first inner anchor and the second inner anchor.

2. The self-tightening reinforcement structure for shield tunnel structure deformation according to claim 1 is characterized in that: The contact surface between the first inner anchor and the outer anchor, and the contact surface between the second inner anchor and the outer anchor are both curved surfaces.

3. The self-tightening reinforcement structure for shield tunnel structure deformation according to claim 1 is characterized in that: The first inner anchor, the second inner anchor and the outer anchor are all made of steel.

4. The method for reinforcing a self-tightening reinforcement structure for a shield tunnel structure deformation according to any one of claims 1 to 3, characterized in that: The following steps are involved: S1, tensioning the prestressed steel bar at one end of the standard block to reach the specified tensioning force, and at the same time making the first inner anchor and the second inner anchor adjust and contact with the outer anchor respectively; S2, pass the prestressed steel bar through the original anchor position of the standard block segment, tension it to the specified prestressing force and then fix it with bolts; S3. During normal use, the joints at both ends of the adjacent segments are subjected to the tensile force of the prestressed steel bars to limit deformation; S4. When the cracking effect continues to increase, the crack deformation causes the prestressed steel bars to be tensioned. At this time, the prestressed steel bars and the first inner anchorage and the second inner anchorage move relative to the outer anchorage at the same time, and the first inner anchorage and the second inner anchorage enter the next outer anchorage; the stress of the prestressed steel bars behind the first inner anchorage and the second inner anchorage increases to limit the crack width on this side of the adjacent block segment.

5. The method for reinforcing a self-tightening reinforcement structure for a shield tunnel structure deformation according to claim 4, characterized in that: Stress strain gauges are attached to the prestressed steel bars at the front and rear ends of the first inner anchor and the second inner anchor respectively. When the stress strain gauges sense that the forces on the prestressed steel bars on both sides of the first inner anchor and the second inner anchor are different, they will feedback to the management department. Workers will tension and fix the prestressed steel bars on the side with smaller stress, i.e., the front end of the movable first inner anchor and the second inner anchor to improve the overall strength and reduce the crack width.

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