Shield segment structure reinforcing method

Abstract

The invention discloses a shield segment structure reinforcing method. The shield segment structure reinforcing method comprises the following steps that S1, segments are prefabricated; s2, site construction is conducted, the duct piece comprises a main body and a plurality of reinforcing structures, the main body is arranged to be of a cambered surface duct piece structure of a preset size, the reinforcing structures are arranged on the surface of the main body, each reinforcing structure extends in the axial direction of the main body, every two reinforcing structures are arranged in parallel, and every two adjacent reinforcing structures are spaced by a preset distance; and each reinforcing structure is provided with a trapezoidal connecting groove, and the trapezoidal connecting grooves are formed in the end faces of the reinforcing structures so as to be used for axial connection between the pipe pieces. The flexural rigidity of the duct piece is improved by arranging the reinforcing structure so as to adapt to more complex geological conditions; the connection mode of a traditional lock catch is optimized through the trapezoid connection grooves, assembly errors can be effectively reduced through the trapezoid design, and meanwhile the anti-shearing performance of the joints of the pipe pieces is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of shield segments, and particularly to a method for strengthening the structure of shield segments. Background Art

[0002] Shield segments are important precast components used to support the tunnel excavation face and form the permanent structure of the tunnel during shield tunneling construction. They are usually cast from high-strength concrete and assembled into a ring to form the lining structure of the tunnel. Specifically, shield segments are usually designed as multiple block-shaped components (generally 4 to 8 pieces), which are assembled to form a complete ring; each segment usually uses high-performance concrete (such as C50 or C60), and some projects will combine steel bars or composite materials for reinforcement; to ensure the assembly accuracy, shield segments are precast in the factory with strict control of dimensional errors; the segments are connected by bolts or mechanical locks to ensure the overall stability after assembly. Based on this, during the shield tunnel boring process, the segments can support the formation pressure and prevent the excavation face from collapsing; as part of the tunnel inner wall, the segments bear the pressure of the surrounding soil and groundwater to ensure the stability of the tunnel; through the sealed joint design between the segments, groundwater leakage is effectively prevented; the segments need to bear the thrust during shield machine tunneling and disperse it into the surrounding formation.

[0003] In the existing shield segments, a steel reinforcement cage is used as a strengthening structure during the casting process to improve the strength of the segments and can be used for the connection between the segments. The addition of steel bars can significantly increase the flexural strength and tensile strength of the segments, thereby improving the overall bearing capacity of the segments. The steel bars play a constraining role on the segment concrete and enhance its flexural and shear resistance. At the same time, threaded steel bars are mainly used to connect different segments during the segment production. After the segments are stacked, the threaded steel bars serve as the connection foundation to ensure the firm connection between the segments. However, the above-mentioned type of segments has insufficient crack resistance on the surface, and the steel bars are prone to corrosion during use, which greatly reduces the durability of the segments and shortens their service life. Summary of the Invention

[0004] Based on this, in view of the technical problem of insufficient surface strength and durability of the existing shield segments, it is necessary to provide a method for strengthening the structure of shield segments.

[0005] A method for strengthening the structure of shield segments, the method for strengthening the structure of shield segments includes the following steps: S1, segment prefabrication; S2, on-site construction.

[0006] The above-mentioned step S1 includes the following steps: S11. Preset CFRP grids inside the customized steel mold, and fix the CFRP grids at preset intervals to ensure that the grids do not shift during the concrete pouring process; S12. Put cement, medium sand, gravel, water, and additives into the mixing device according to the preset component ratio and carry out mixing work for a preset time and at a preset temperature to obtain concrete; S13. Pour the first layer of concrete into the steel mold until it reaches 50% of the mold depth, and combine vibration compaction treatment. After fixing the CFRP grids to the preset positions, carry out the second layer of pouring until it reaches the top of the mold, and then carry out secondary vibration for exhaust; S14. Sequentially obtain the segments through steam curing and natural curing.

[0007] The above-mentioned step S2 includes the following steps: S21. Transport the segments to the construction site; S22. Locate the bottom segment through the laser positioning system and install positioning pins to ensure accurate position; S23. Install the side segments in sequence, tighten the bolts to the initial torque for each installed segment, and then install the closure segment, adjust the bolts and tighten them to the design torque; S24. Inject polyurethane sealant at the joints to ensure no water seepage between the segments; S25. Real-time detect the force distribution of the segments through the embedded sensors, and carry out a spray test after completing the installation of one ring to ensure no water leakage at the joints.

[0008] The above-mentioned segment includes a main body and several strengthening structures. The main body is set as an arc-shaped segment structure with a preset size, and several strengthening structures are arranged on the surface of the main body.

[0009] Each strengthening structure is provided with a trapezoidal connection groove, and the trapezoidal connection groove is arranged at the end face of the strengthening structure for axial connection between the segments.

[0010] In one embodiment, each of the above-mentioned strengthening structures extends along the axial direction of the main body, several strengthening structures are arranged parallel to each other in pairs, and the adjacent two strengthening structures are spaced at a preset distance.

[0011] In one embodiment, one end of each of the above-mentioned strengthening structures is provided with two trapezoidal connection grooves arranged in a stacked manner.

[0012] In one embodiment, each of the above-mentioned strengthening structures further includes a first installation groove, and the first installation groove is arranged on the inner surface of the strengthening structure for accommodating and installing sensors.

[0013] In one embodiment, the above-mentioned main body further includes a first matching portion and a second matching portion. The first matching portion and the second matching portion are respectively arranged at the two side edges of the main body, and the first matching portion and the second matching portion can be correspondingly matched, so that adjacent segments can be connected to each other through the first matching portion and the second matching portion.

[0014] In one embodiment, the above-mentioned first mating portion is provided with a second mounting groove, and the second mounting groove extends along the length direction of the first mating portion.

[0015] In one embodiment, in the above-mentioned step S11, the fixed interval of the CFRP grid is set to 200 mm to ensure the installation stability of the CFRP grid.

[0016] In one embodiment, in the above-mentioned step S12, the proportion of the concrete components includes 400 parts of cement, 600 parts of medium sand, 1200 parts of gravel, 160 parts of water, and 1.5 wt% of superplasticizer.

[0017] In one embodiment, the above-mentioned cement is P.O 52.5 cement.

[0018] In one embodiment, the particle size of the above-mentioned gravel is set to 5 - 20 mm.

[0019] In one embodiment, in the above-mentioned step S12, the mixing time is set to 3 min. Specifically, the mixing time includes 1 min of dry mixing and 2 min of wet mixing to ensure that the concrete is fully and evenly mixed.

[0020] In one embodiment, in the above-mentioned step S12, the mixing temperature is set to 20 - 25 °C to avoid affecting the performance of the concrete due to overheating of the hydration reaction.

[0021] In one embodiment, in the above-mentioned step S13, the total pouring time is limited within 30 min.

[0022] In one embodiment, in the above-mentioned step S14, the steam curing condition is set to 60 °C for 12 h; the natural curing condition is set to keep the indoor humidity at 90% for 7 d.

[0023] In one embodiment, in the above-mentioned step S23, the initial torque is set to 30 - 100 N·m; the design torque is set to 60 - 200 N·m.

[0024] The above shield segment structure reinforcement method effectively improves the compressive, tensile and crack resistance properties of shield segments by introducing CFRP grids into the concrete. At the same time, it reduces the corrosion problems that may be caused by traditional steel bars. Moreover, the problem of insufficient sealing performance of traditional segment joints is solved by sealing and bonding the joints with polyurethane sealant, further enhancing the durability and impermeability of shield segments. In addition, through the processing technology of layered pouring and simultaneous vibration treatment, the problem of air bubbles that may be caused by traditional single pouring can be effectively avoided, thereby improving the density of concrete. At the same time, for the segment itself, the bending stiffness of the segment is improved by setting a strengthening structure to adapt to more complex geological conditions. The trapezoidal connection groove optimizes the connection method of traditional locks. Through the trapezoidal design, the assembly error can be effectively reduced, and at the same time, the shear resistance performance at the segment joints is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic structural diagram of the shield segment structure reinforcement method in an embodiment. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0026] In order to make the above objects, features and advantages of the present invention more obvious and understandable, the following detailed description of the specific embodiments of the present invention will be given with reference to the accompanying drawings. Many specific details are set forth in the following description in order to fully understand the present invention. However, the present invention can be implemented in many other ways different from those described herein. Those skilled in the art can make similar improvements without departing from the connotation of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed below.

[0027] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of the present invention.

[0028] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, "a plurality" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0029] In the present invention, unless otherwise clearly defined or limited, terms such as "installed", "connected", "joined", "fixed", etc. shall be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral one; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the internal communication between two elements or the interaction relationship between two elements, unless otherwise clearly defined. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0030] In the present invention, unless otherwise clearly defined or limited, the first feature being "on" or "under" the second feature may be that the first and second features are in direct contact, or the first and second features are indirectly in contact through an intermediate medium. Moreover, the first feature being "above", "over" and "on top of" the second feature may be that the first feature is directly above or obliquely above the second feature, or merely indicates that the horizontal height of the first feature is higher than that of the second feature. The first feature being "under", "below" and "beneath" the second feature may be that the first feature is directly below or obliquely below the second feature, or merely indicates that the horizontal height of the first feature is lower than that of the second feature.

[0031] It should be noted that when an element is referred to as "fixed to" or "disposed on" another element, it may be directly on the other element or there may also be an intermediate element. When an element is considered to be "connected" to another element, it may be directly connected to the other element or there may be an intermediate element at the same time. The terms "vertical", "horizontal", "up", "down", "left", "right" and similar expressions used herein are only for the purpose of illustration and do not represent the only implementation.

[0032] Please refer to Figure 1, the present invention discloses a method for strengthening the shield segment structure, which includes the following steps: S1, segment prefabrication; S2, on-site construction. Among them, the above step S1 includes the following steps: S11, preset a CFRP grid inside the customized steel mold, and fix the CFRP grid at preset intervals to ensure that the grid does not displace during the concrete pouring process; S12, put cement, medium sand, gravel, water and additives into the mixing device according to the preset component ratio and carry out the mixing work for a preset time and at a preset temperature to obtain concrete; S13, pour the first layer of concrete into the steel mold until it reaches 50% of the mold depth, and combine it with vibration compaction treatment. After fixing the CFRP grid to the preset position, carry out the second layer pouring until it reaches the top of the mold, and then carry out secondary vibration exhaust; S14, obtain the segment through steam curing and natural curing in sequence. The above step S2 includes the following steps: S21, transport the segment to the construction site; S22, position the bottom segment through the laser positioning system and install positioning pins to ensure accurate position; S23, install the side segments in sequence, tighten the bolts to the initial torque for each installed segment, and then install the closure segment, adjust the bolts and tighten them to the design torque; S24, inject polyurethane sealant at the joints to ensure no water seepage between the segments; S25, use embedded sensors to detect the force distribution of the segments in real time, and carry out a spray test after completing the installation of one ring to ensure no water leakage at the joints. Specifically, the above segment includes a main body 100 and a number of strengthening structures 200. The main body 100 is set as an arc-shaped segment structure with a preset size, and a number of strengthening structures 200 are arranged on the surface of the main body 100. Among them, each strengthening structure 200 extends along the axial direction of the main body 100, and a number of strengthening structures 200 are arranged parallel to each other in pairs. Moreover, the adjacent two strengthening structures 200 are spaced at a preset distance to strengthen the structural strength of the main body 100. More specifically, each strengthening structure 200 is provided with a trapezoidal connection groove a, and the trapezoidal connection groove a is arranged at the end face of the strengthening structure 200 for axial connection between the segments. In one embodiment, two trapezoidal connection grooves a are stacked at one end of each strengthening structure 200 to enhance the connection strength between the segments.

[0033] Furthermore, each strengthening structure 200 further includes a first installation groove b, and the first installation groove b is arranged on the inner surface of the strengthening structure 200 for accommodating and installing sensors. In practical applications, the sensors are connected to the tunnel monitoring system to monitor the stress distribution and deformation of the top segment and the joint area in real time.

[0034] Further, the main body 100 further includes a first fitting portion 110 and a second fitting portion 120. The first fitting portion 110 and the second fitting portion 120 are respectively arranged at two side edges of the main body 100, and the first fitting portion 110 and the second fitting portion 120 can be correspondingly fitted, so that adjacent segments can be fitted and connected to each other through the first fitting portion 110 and the second fitting portion 120. Specifically, the first fitting portion 110 is provided with a second installation groove c, and the second installation groove c extends along the length direction of the first fitting portion 110 for installing a waterproof rubber strip.

[0035] Further, in the above step S11, the fixed interval of the CFRP grid is set to 200 mm to ensure the installation stability of the CFRP grid.

[0036] Further, in the above step S12, the concrete component ratio includes 400 parts of cement, 600 parts of medium sand, 1200 parts of gravel, 160 parts of water, and 1.5 wt% of superplasticizer. In one embodiment, P.O 52.5 cement is used for the cement. In another embodiment, the particle size of the gravel is set to 5 - 20 mm.

[0037] Further, in the above step S12, the mixing time is set to 3 min. Specifically, the mixing time includes 1 min of dry mixing and 2 min of wet mixing to ensure that the concrete is fully and evenly mixed.

[0038] Further, in the above step S12, the mixing temperature is set to 20 - 25 °C to avoid affecting the concrete performance due to overheating of the hydration reaction.

[0039] Further, in the above step S13, the total pouring time is limited within 30 min.

[0040] Further, in the above step S14, the steam curing condition is set to 60 °C for 12 h; the natural curing condition is set to the indoor humidity controlled at 90% for 7 d.

[0041] Further, in the above step S23, the initial torque is set to 30 - 100 N·m; the design torque is set to 60 - 200 N·m.

[0042] In summary, the method for strengthening the shield segment structure disclosed in the present invention effectively improves the compressive, tensile, and crack resistance properties of the shield segment by introducing CFRP grids into the concrete. At the same time, it reduces the corrosion problems that may be caused by traditional steel bars. Moreover, the problem of insufficient sealing performance of traditional segment joints is solved by sealing and bonding the joints with polyurethane sealant, further enhancing the durability and impermeability of the shield segment. In addition, through the processing technology of layered pouring and simultaneous vibration treatment, the problem of air bubbles that may be caused by traditional single pouring can be effectively avoided, thereby improving the density of the concrete. At the same time, for the segment itself, the bending stiffness of the segment is increased by setting a strengthening structure to adapt to more complex geological conditions. The trapezoidal connection groove optimizes the connection method of traditional locks. Through the trapezoidal design, the assembly error can be effectively reduced, and at the same time, the shear resistance performance at the segment joint is improved.

[0043] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0044] The above-described embodiments only represent several implementation manners of the present invention. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several deformations and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the invention patent should be subject to the appended claims.

Claims

1. A method for reinforcing a shield segment structure, characterized in that: include: The following steps: S1, prefabrication of pipe segments; S2, on-site construction; The step S1 comprises the following steps: S11, presetting a CFRP grid inside the customized steel mold, and fixing the CFRP grid intervals at a preset spacing to ensure that the grid does not move during the concrete pouring process; S12, adding cement, medium sand, gravel, water and admixtures into a stirring device according to a preset component ratio for a preset time and a preset temperature to obtain concrete; S13, pouring a first layer of concrete into the steel mold to 50% of the mold depth, and combining with vibration compaction treatment, fixing the CFRP grid to a preset position and then pouring the second layer, and pouring it to the top of the mold, and then performing secondary vibration exhaust; S14, obtaining the pipe segment through steam curing and natural curing in sequence; The step S2 comprises the following steps: S21, transporting the pipe segment to the construction site; S22, positioning the bottom pipe segment by a laser positioning system, and installing positioning pins to ensure accurate positioning; S23, installing the side segments in sequence, tightening the bolts to the initial torque for each piece installed, and then installing the capping block, adjusting the bolts and tightening them to the designed torque; S24, injecting polyurethane sealant at the joints to ensure that there is no water seepage between the pipe segments; S25, detecting the force distribution of the pipe segment in real time by an embedded sensor, and performing a spray test after completing one ring installation to ensure that there is no water leakage at the joints; The tube segment comprises a main body and a plurality of reinforcement structures, wherein the main body is a curved tube segment structure of a preset size, and the plurality of reinforcement structures are arranged on the surface of the main body; Each reinforcement structure is provided with a trapezoidal connection groove, which is arranged on the end surface of the reinforcement structure for axial connection between the pipe segments.

2. The shield segment structure reinforcement method according to claim 1, characterized in that: In the step S11, the fixed interval of the CFRP grid is set to 200 mm, so as to ensure the installation stability of the CFRP grid.

3. The shield segment structure reinforcement method according to claim 2, characterized in that: In step S12, the concrete component ratio includes 400 parts of cement, 600 parts of medium sand, 1200 parts of gravel, 160 parts of water and 1.5 wt% of superplasticizer.

4. The shield segment structure reinforcement method according to claim 3, characterized in that: The cement used is PO 52.5 cement.

5. The shield segment structure reinforcement method according to claim 4, characterized in that: The stone particle size is set to 5-20mm.

6. The shield segment structure reinforcement method according to claim 5, characterized in that: In step S12, the mixing time is set to 3 minutes. Specifically, the mixing time includes 1 minute for dry mixing and 2 minutes for wet mixing to ensure that the concrete is fully mixed and uniform.

7. The shield segment structure reinforcement method according to claim 6, characterized in that: In step S12, the stirring temperature is set to 20-25°C to avoid overheating of the hydration reaction affecting the performance of the concrete.

8. The shield segment structure reinforcement method according to claim 7, characterized in that: In step S13, the total pouring time is limited to within 30 minutes.

9. The shield segment structure reinforcement method according to claim 8, characterized in that: In step S14, the steam curing condition is set to 60° C. for 12 hours; the natural curing condition is set to control the indoor humidity at 90% for 7 days.

10. The shield segment structure reinforcement method according to claim 9, characterized in that: In step S23, the initial torque is set to 30-100 N·m; the design torque is set to 60-200 N·m.

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