UHPC-steel-nc combined segment and construction method thereof

Abstract

The application discloses a UHPC-type steel-NC combined pipe segment and a construction method thereof, and relates to the technical field of tunnel engineering. The pipe segment comprises UHPC joints at two ends, a common concrete pipe segment main body at the middle, and an embedded I-shaped steel arch; the UHPC joints are bonded with the common concrete main body through trapezoidal grooves, and the compressive strength is greater than or equal to 120 MPa; the I-shaped steel arch is arranged between the main reinforcement of the steel reinforcement cage, and forms an integral whole through a hat-shaped steel connecting plate, so that the bending stiffness is enhanced; the pipe segment is provided with a first bolt hole, a second bolt hole and a grouting hole, and the bolt holes penetrate the UHPC joints and are connected with the hand holes. Through the UHPC reinforced joints and the steel reinforced main body, the application solves the problems of insufficient joint strength and poor durability of the traditional pipe segment under high water pressure environment, significantly improves the impermeability, the bearing capacity and the service life, and reduces the construction cost.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of tunnel engineering, and particularly relates to a UHPC-steel-NC combined segment and a construction method thereof. BACKGROUND

[0002] With the acceleration of urbanization and the growth of traffic demand, shield tunnels have become the core means of urban subway construction as an efficient underground construction technology. Traditional shield tunnel segments are mostly made of reinforced concrete structures, but there are significant defects in complex geological environments such as high water pressure and soft rock large deformation:

[0003] Insufficient bearing capacity: ordinary concrete (NC) segments are difficult to resist external high pressure and deformation, which easily leads to concrete damage;

[0004] Structural limitations: to improve the bearing capacity, the thickness of the segment needs to be increased, which forces the redesign of the shield machine and significantly increases the construction cost;

[0005] Durability defects: the impermeability of the concrete joint area is weak, which is easily affected by water erosion, freeze-thaw and chemical corrosion, shortening the service life of the tunnel;

[0006] High difficulty in assembly: when the geological conditions are complex, the segment splicing is prone to problems such as falling off and poor sealing, which threatens the overall safety of the tunnel.

[0007] Current technologies try to optimize materials and structures, but they cannot effectively balance the mechanical properties, durability and cost. For example, the strength of cast-in-place concrete joints is insufficient, and the use of ultra-high performance concrete (UHPC) in the full cross-section is too high in cost; the bending stiffness and high axial pressure resistance of ordinary steel cages are limited, and they are prone to deformation and cracking under long-term load, and even collapse.

[0008] Therefore, there is an urgent need to develop a new combined segment structure that has high bearing capacity, excellent durability and economy. SUMMARY

[0009] The purpose of the embodiments of the application is to provide a UHPC-steel-NC combined segment and a construction method thereof, which solves the problems of insufficient joint strength and poor durability of traditional segments in high water pressure environments, significantly improves impermeability, bearing capacity and service life, and reduces construction cost.

[0010] To solve the above technical problems, the application is implemented as follows:

[0011] The embodiments of the application provide a UHPC-steel-NC combined segment, which comprises:

[0012] UHPC joint, ordinary concrete segment body, I-shaped steel arch, segment base steel cage, UHPC structural steel cage, first bolt hole, second bolt hole and grouting hole.

[0013] The ordinary concrete segment body is located in the middle of the segment, and wraps the I-shaped steel arch and the segment base steel reinforcement cage. The outer arc surface of the ordinary concrete segment body is provided with the grouting hole, and the inner arc surface is provided with a through bolt hand hole.

[0014] The UHPC joint is located at both ends of the segment, wraps the UHPC structural steel reinforcement cage, and is bonded with the ordinary concrete segment body through a groove;

[0015] The first bolt hole penetrates the unbonding side of the UHPC joint and the ordinary concrete segment body, and is connected with the bolt hand hole.

[0016] The second bolt hole penetrates the fan ring side surface of the ordinary concrete segment body, and is connected with the bolt hand hole.

[0017] The I-shaped steel arch is embedded in the interior of the ordinary concrete segment body, and is connected with the segment base steel reinforcement cage through a hat-shaped steel connecting steel plate to form an integral whole.

[0018] Optionally, the UHPC joint and the bonding side of the ordinary concrete segment body are provided with a trapezoidal groove, the long side of the groove is 100 mm, the short side is 80 mm, and the depth is 50 mm.

[0019] Optionally, the compressive strength of the UHPC joint is ≥120 MPa, and the axial tensile strength is ≥8 MPa.

[0020] Optionally, the I-shaped steel arch adopts a model of Q235 and above, the height is ≥100 mm, the flange width is ≥100 mm, the flange thickness is ≥10 mm, and the web thickness is ≥15 mm; the distance between the I-shaped steel arch and the bolt hand hole is ≥30 mm.

[0021] Optionally, the hat-shaped steel connecting steel plate connects the I-shaped steel arch and the segment base steel reinforcement cage, and limits the intrusion of the I-shaped steel into the UHPC joint area.

[0022] Optionally, the segment base steel reinforcement cage comprises:

[0023] The upper and lower main reinforcement is made of HRB400 steel, and the reinforcement ratio is ≥0.8%, and the distance between adjacent main reinforcements is ≥100 mm.

[0024] The stirrup is made of HPB300 steel and is arranged at intervals between adjacent I-shaped steel arches.

[0025] Optionally, the first bolt hole is arranged on the unbonding side of the UHPC joint, the second bolt hole is arranged on the fan ring side surface, and the bolt hand hole is in communication with the first bolt hole and the second bolt hole, respectively.

[0026] The application further provides a construction method of the UHPC-steel-NC combined segment.

[0027] (a) prefabricating a UHPC joint with trapezoidal grooves;

[0028] (b) binding a segment main body steel reinforcement cage, processing an I-shaped steel arch frame, and assembling the two to form an assembly body through a cap-shaped steel connecting plate;

[0029] (c) hoisting the assembly body into a mold, and installing a grouting hole reserved sleeve and a UHPC joint;

[0030] (d) pouring ordinary concrete, and demolding after 24 hours of curing;

[0031] (e) water curing for 15 days after steam curing, and naturally curing for 28 days.

[0032] Compared with the prior art, the application has the beneficial effects that:

[0033] (1) the UHPC joint (compressive strength ≥ 120 MPa, axial tensile strength ≥ 8 MPa) is adopted, the bearing capacity and crack resistance of the joint area are greatly improved, and the problem that the traditional concrete joint is prone to failure in a high-pressure and soft rock environment is solved. The groove design (trapezoidal groove, depth 50 mm) enhances the bonding performance of the UHPC and the ordinary concrete (NC), and ensures effective load transmission.

[0034] (2) the I-shaped steel arch (Q235 type, height ≥ 100 mm) is arranged in the segment main body, and the steel reinforcement cage and the I-shaped steel arch form an integral structure through the cap-shaped steel connecting plate, so that the bending stiffness and shear bearing capacity are significantly improved. The I-shaped steel is located between the main reinforcement, avoids invading the bolt hole (interval ≥ 30 mm), optimizes the internal force distribution while ensuring the structural integrity, and reduces stress concentration.

[0035] (3) the UHPC joint has super-high density, can significantly resist high water pressure penetration, freeze-thaw cycle and chemical corrosion, and solves the problem that the traditional segment joint is prone to water penetration and deterioration.

[0036] (4) the I-shaped steel reinforcing system effectively inhibits the deformation and cracking of the segment after long-term stress, and prolongs the service life of the tunnel. The cooperative design of the ordinary concrete main body (C50) and the UHPC takes into account the economy and the durability of the key parts.

[0037] (5) the I-shaped steel replaces part of the steel reinforcement (main reinforcement reinforcement ratio ≥ 0.8%), reduces the amount of steel reinforcement; and the UHPC is only used in the joint part, avoiding the high cost of overall use.

[0038] (6) The double bolt hole system (the first bolt hole penetrates the UHPC joint, and the second bolt hole is located on the side of the fan ring) combined with the hand hole design improves the assembly accuracy of the segments and the sealing of the joints, reducing the risk of leakage. The grouting hole (middle of the outer arc surface) optimizes the grouting process and improves the overall waterproof performance of the tunnel.

[0039] (7) Precast UHPC joints and main body are cast in stages (precast UHPC first, then cast NC main body). The process is mature and the quality control is convenient, making it suitable for large-scale production.

[0040] (8) Reduce segment thickness (no need to thicken due to insufficient strength), maintain the original design of the tunnel boring machine, and save construction costs. The durability of UHPC reduces long-term maintenance costs, and the reinforcing effect of I-beams delays structural deterioration. It has stable performance in harsh environments such as high water pressure and large deformation of soft rock, reducing construction risks and failure handling costs.

[0041] In summary, the combined tunnel segments provided by this invention comprehensively address the pain points of traditional tunnel segments, such as fragile joints, poor durability, and high cost, through local reinforcement of UHPC joints, strengthening of the I-beam body, and refined structural design. They are suitable for shield tunnel projects in high water pressure and large deformation strata, and have the triple advantages of safety, durability, and economy. Attached Figure Description

[0042] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort, wherein:

[0043] Figure 1 This is a schematic diagram of a single-piece segment for localized joint reinforcement provided by the present invention;

[0044] Figure 2 This is a schematic diagram of a single-piece segment structure with localized joint reinforcement provided by the present invention;

[0045] Figure 3 For along Figure 2 Schematic diagram of the cross section of line AA in the middle;

[0046] Figure 4 For along Figure 2 Schematic diagram of the cross section of the middle BB line;

[0047] Figure 5 For along Figure 2 Schematic diagram of the cross section of the CC line;

[0048] Figure 6 For along Figure 2 A cross-sectional schematic diagram of the DD line.

[0049] In the figure, 1, UHPC joint; 2, ordinary concrete segment main body; 3, I-shaped steel arch; 4, segment base reinforcement cage; 5, UHPC structure reinforcement cage; 6, bolt hand hole; 7, cap type steel connecting steel plate; 8, steel plate connecting stud; 10, first bolt hole; 9, second bolt hole; 11, grouting hole; 12, outer arc surface; 13, inner arc surface; 14, bonding side; 15, non-bonding side. DETAILED DESCRIPTION

[0050] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0051] The terms "first", "second" and the like in the specification and claims of the present application are used to distinguish similar objects, and are not used to describe a particular order or sequence. It should be understood that the data used in this way can be interchanged under appropriate circumstances, so that the embodiments of the present application can be implemented in an order other than those illustrated or described herein, and the objects distinguished by "first", "second" and the like are generally of a kind and are not limited in number, for example, the first object can be one or more. In addition, "and / or" in the specification and claims indicates at least one of the connected objects, and the character " / ", generally indicates that the front and rear associated objects are in an "or" relationship.

[0052] Please refer to Figures 1 to 6 As shown in the figure, the embodiment of the present application provides a UHPC-steel-NC combined segment, which comprises a UHPC joint 1, an ordinary concrete segment main body 2, an I-shaped steel arch 3, a segment base reinforcement cage 4, a UHPC structure reinforcement cage 5, a bolt hand hole 6, a cap type steel connecting steel plate 7, a steel plate connecting stud 8, a first bolt hole 10, a second bolt hole 9 and a grouting hole 11.

[0053] Further referring to Figure 1 As shown in the figure, the ordinary concrete segment main body 2 is located in the middle of the segment, and wraps the I-shaped steel arch 3 and the segment base reinforcement cage 4. The outer arc surface 12 of the ordinary concrete segment main body 2 is provided with the grouting hole 11, and the inner arc surface 13 is provided with a through bolt hand hole 6.

[0054] Further referring to Figure 2 and Figure 3 As shown in the figure, the UHPC joint 1 is located at both ends of the segment, wraps the UHPC structure reinforcement cage 5, and is bonded with the ordinary concrete segment main body 2 through grooving.

[0055] Specifically, the bonding side 14 of the UHPC joint 1 and the ordinary concrete segment body 2 is provided with a trapezoidal groove, the long side of the groove is 100 mm, the short side is 80 mm, and the depth is 50 mm. Through the design of the groove, the bonding performance of UHPC and ordinary concrete (NC) can be enhanced, and the effective load transfer can be ensured.

[0056] In particular, referring to Figure 5 As shown, the first bolt hole 10 penetrates the non-bonding side 15 of the UHPC joint 1 and the ordinary concrete segment body 2, and is connected with the bolt hand hole 6.

[0057] In a specific embodiment, the first bolt hole 10 is arranged on the non-bonding side 15 of the UHPC joint, the number is 4 and the center is symmetrically arranged; the second bolt hole 9 is arranged on the side surface of the fan ring, the number is 6 and the center is symmetrically arranged; the number of the bolt hand hole 6 is 10, which respectively communicates with the first bolt hole 10 and the second bolt hole 9.

[0058] The double bolt hole system (the first bolt hole penetrates the UHPC joint, and the second bolt hole is located on the side surface of the fan ring) combined with the hand hole design can improve the segment assembly precision and the joint sealing performance, and reduce the leakage risk. The grouting hole (in the middle of the outer arc surface) optimizes the grouting process and improves the overall waterproof performance of the tunnel.

[0059] The I-shaped steel arch 3 is embedded in the inside of the ordinary concrete segment body 2, and is connected with the segment base steel reinforcement cage 4 through the hat-shaped steel connecting plate 7 to form a whole, so that the bending stiffness and shear bearing capacity can be significantly improved.

[0060] The compressive strength of the UHPC joint 1 is ≥120MPa, and the axial tensile strength is ≥8MPa, so that the carrying capacity and crack resistance of the joint area can be greatly improved, and the problem that the traditional concrete joint is easy to fail in high pressure and soft rock environment can be solved.

[0061] The I-shaped steel arch 3 adopts Q235 and above models, the height is ≥100mm, the flange width is ≥100mm, the flange thickness is ≥10mm, and the web thickness is ≥15mm; the distance between the I-shaped steel arch 3 and the bolt hand hole 6 is ≥30mm, so that the I-shaped steel arch 3 does not invade the bolt hand hole 6, the structural integrity is ensured, the internal force distribution is optimized, and stress concentration is reduced.

[0062] The hat-shaped steel connecting plate 7 connects the I-shaped steel arch 3 and the segment base steel reinforcement cage 4, and limits the invasion of the I-shaped steel into the UHPC joint 1 area.

[0063] The segment base steel reinforcement cage 4 comprises:

[0064] The upper and lower main reinforcement is made of HRB400 steel, the diameter is 18mm, the reinforcement ratio is ≥0.8%, and the distance between adjacent main reinforcement is ≥100mm.

[0065] Stirrups, using HPB300 steel bars, the diameter is selected 8mm, is arranged between the adjacent I-shaped steel arches.

[0066] Further, the main reinforcement and the stirrup are connected into a cage by welding or binding.

[0067] The I-shaped steel replaces part of the steel bars (the reinforcement ratio of the main reinforcement is greater than or equal to 0.8%), and the amount of steel bars is reduced; the UHPC is only used in the local joint, and the high cost of overall use is avoided.

[0068] The application further provides a construction method of the UHPC-type steel-NC combined segment.

[0069] (a) prefabricating the UHPC joint 1 with trapezoidal grooves;

[0070] (b) binding the segment base steel bar cage 4, processing the I-shaped steel arch 3 frame, and assembling the two to form an assembly body through the cap-shaped steel connecting plate 7;

[0071] (c) hoisting the assembly body into a mold, and installing a grouting hole reserved sleeve and the UHPC joint 1;

[0072] (d) pouring ordinary concrete, and demolding after 24 hours of curing;

[0073] (e) water curing for 15 days after steam curing, and naturally curing for 28 days.

[0074] It should be noted that in this text, the terms "include", "contain" or any other variant thereof are intended to cover non-exclusive inclusion, so that the process, method, article or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed, or includes elements inherent to such process, method, article or device. Without more limitations, the element defined by the statement "including a" does not exclude the presence of another identical element in the process, method, article or device including the element.

[0075] In addition, it should be noted that the scope of the methods and systems in the embodiments of the application is not limited to performing functions in the order shown or discussed, but can also include performing functions in a substantially simultaneous manner or in reverse order according to the functions involved, for example, the described method can be performed in an order different from that described, and various steps can also be added, omitted or combined. In addition, the features described with reference to certain examples can be combined in other examples.

[0076] The embodiments of the present application are described above with reference to the accompanying drawings, but the present application is not limited to the above-described specific embodiments, and the above-described specific embodiments are merely illustrative, but not restrictive, and a person of ordinary skill in the art can make many forms under the inspiration of the present application without departing from the purpose of the present application and the scope protected by the claims, and all of them belong to the protection of the present application.

Claims

1. A UHPC-steel-NC composite segment, characterized in that, include: UHPC joint (1), ordinary concrete segment body (2), I-shaped steel arch frame (3), segment base reinforcement cage (4), UHPC structural reinforcement cage (5), first bolt hole (10), second bolt hole (9) and grouting hole (11). The ordinary concrete pipe segment body (2) is located in the middle of the pipe segment, and wraps the I-shaped steel arch frame (3) and the pipe segment base reinforcement cage (4); the outer arc surface (12) of the ordinary concrete pipe segment body (2) is provided with the grouting hole (11), and the inner arc surface (13) is provided with the through bolt hand hole (6). The UHPC joint (1) is located at both ends of the segment, wraps the UHPC structural steel cage (5), and is bonded to the bonding side (14) of the ordinary concrete segment body (2) through a trapezoidal groove. The long side of the trapezoidal groove is 100mm, the short side is 80mm, and the depth is 50mm. The first bolt hole (10) penetrates the non-bonded side (15) of the UHPC joint (1) and the ordinary concrete segment body (2) and is connected to the bolt hand hole (6). The second bolt hole (9) penetrates the side of the fan ring of the ordinary concrete segment body (2) and is connected to the bolt hand hole (6); the second bolt hole (9) is located above the I-shaped steel arch frame (3); The I-shaped steel arch frame (3) is embedded inside the ordinary concrete pipe segment body (2) and is connected to the pipe segment base reinforcement cage (4) by the capped steel connecting plate (7) to form an integral whole. The capped steel connecting plate (7) restricts the I-shaped steel arch frame (3) from intruding into the UHPC joint (1) area. The compressive strength of the UHPC connector (1) is ≥120MPa, and the axial tensile strength is ≥8MPa. The number of the first bolt holes (10) is 4 and they are centrally symmetrically arranged on the non-bonded side (15) of the UHPC connector. The number of the second bolt holes (9) is 6 and they are centrally symmetrically arranged on the side of the fan ring. The number of bolt hand holes (6) is 10, which are respectively connected to the first bolt holes (10) and the second bolt holes (9).

2. The UHPC-steel-NC composite segment according to claim 1, characterized in that, The I-shaped steel arch frame (3) adopts Q235 or above, with a height ≥100mm, flange width ≥100mm, flange thickness ≥10mm, and web thickness ≥15mm; the distance between the I-shaped steel arch frame (3) and the bolt hand hole (6) is ≥30mm.

3. The UHPC-steel-NC composite segment according to claim 1, characterized in that, The segment base reinforcement cage (4) includes: The upper and lower main reinforcement bars are made of HRB400 steel bars with a reinforcement ratio of ≥0.8% and a spacing of ≥100mm between adjacent main reinforcement bars; The stirrups, made of HPB300 steel bars, are spaced apart between adjacent I-shaped steel arches.

4. A construction method of a UHPC-steel-NC composite segment according to any one of claims 1 to 3, characterized in that, Includes the following steps: (a) Prefabricated UHPC connector with trapezoidal grooves (1); (b) Tie the steel reinforcement cage (4) of the segment base, process the I-shaped steel arch frame (3), and assemble the two into an assembly by connecting the capped steel plate (7); (c) Hoist the assembly into the mold and install the grouting hole pre-reserved sleeve and UHPC connector (1); (d) Pour ordinary concrete and demold after curing for 24 hours; (e) Steam curing followed by water curing for 15 days, then natural curing for 28 days.

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