SMA-based shield segment joint self-adaptive sealing device and construction method

Abstract

The application discloses a shield segment joint self-adaptive sealing device based on SMA and a construction method, relates to the field of shield tunnel engineering, and the self-adaptive sealing device is a strip-shaped composite pad body arranged along the longitudinal direction of a segment joint and embedded in a groove in the side wall of the segment. The strip-shaped composite pad body comprises a skeleton layer, an intermediate energy absorption layer and an outer wear-resistant layer from inside to outside. The skeleton layer is integrally formed by a shape memory alloy through additive manufacturing, and the skeleton layer has a preset three-dimensional wave shape. The intermediate energy absorption layer is coated on the outer side of the skeleton layer and is made of porous elastic material and is used for absorbing impact energy generated during segment assembly and operation. The self-adaptive sealing device based on SMA and the construction method actively generate restoring force to compensate for the loss of contact stress by using the super-elastic effect of the shape memory alloy in combination with the three-dimensional wave-shaped skeleton structure when the joint is deformed, thereby solving the technical problem of the attenuation of sealing force after long-term service caused by the passive response of the existing sealing device.

Description

Technical Field

[0001] This invention relates to shield tunnel engineering technology, specifically to an adaptive sealing device and construction method for shield segment joints based on SMA. Background Technology

[0002] A shield tunnel is an underground structure assembled from several precast concrete segments using bolts. The joints between the segments are weak points prone to water leakage, and their sealing performance directly affects the long-term operational safety and durability of the tunnel. To cope with groundwater pressure and the impact of dynamic loads during operation, elastic sealing gaskets are usually embedded in the grooves on the sidewalls of the segments to form a contact seal.

[0003] To improve sealing performance and adaptability, existing technologies primarily improve sealing performance by altering the gasket's structural form or adding auxiliary components. For example:

[0004] 1) Chinese Patent Publication No. CN110284909B discloses a friction-reducing waterproof sealing gasket for tunnel segments and a waterproof structure for shield tunnel segments. In this patent application, the sealing gasket body has an installation end and a compression end, and the end face of the compression end of the sealing gasket body is provided with a friction-reducing material layer. This invention also provides a waterproof structure for shield tunnel segments, in which sealing gaskets are installed in both waterproof trenches, and at least one of the sealing gaskets is the aforementioned friction-reducing waterproof sealing gasket for tunnel segments; the friction-reducing material layer on the shield tunnel segment with the friction-reducing waterproof sealing gasket is mutually compressed and sealed with the compression end of the sealing gasket on the other shield tunnel segment. This invention effectively reduces the friction coefficient between the contact surfaces of the waterproof sealing gaskets by setting a friction-reducing material layer on the side of the existing waterproof sealing gasket away from the bottom surface of the waterproof trench, thereby effectively alleviating misalignment and significantly improving the waterproof capability of the formed shield tunnel; moreover, the waterproof sealing gasket of this invention can be used in conjunction with ordinary sealing gaskets or friction-reducing sealing gaskets.

[0005] 2) Chinese Patent Publication No. CN118008394A discloses a sliding magnetic sealing gasket for underground structural segments in extremely cold and water-rich environments. In this patent application, a composite sealing gasket is placed between the joint grooves of two concrete segments. It consists of two elastic sealing gaskets facing away from each other, with their contact ends tightly fitted together. The support legs of the elastic sealing gaskets are tightly supported at the bottom of the joint groove. A pre-reserved installation cavity inside the concrete segment houses two U-shaped sliders, two L-shaped sliders, and two I-shaped sliders. During the assembly and approach of the two concrete segments, the two pairs of U-shaped sliders compress against each other, generating displacement that unlocks the L-shaped sliders. The bottom end of the I-shaped slider passes through the perforation of the L-shaped slider and is supported at the bottom of the joint groove, magnetically connected to both sides of the support legs of the elastic sealing gasket. The clever placement of sliders and springs within the concrete segment, combined with the strong magnetic attraction between the sealing gasket and the joint groove after assembly, further ensures a better sealing effect in extremely cold and water-rich environments.

[0006] 3) Chinese Patent Publication No. CN118933847A discloses a segmented isolation type segment sealing gasket and its application method. In this patent application, the segmented isolation type segment sealing gasket has a cage-like structure, including an outer sealing gasket and an inner sealing gasket located on the annular surface and end face of the segment, respectively. The outer sealing gasket and the inner sealing gasket located on the same surface are connected by a cavity sealing gasket. The advantage of this invention is that it can divide the joint surface of the segment into several waterproof zones. Once water seepage occurs at the joint later, the leak point can be found immediately and sealed, reducing the cost of future repairs and sealing.

[0007] The aforementioned solutions improve traditional gaskets from the perspectives of reducing friction, enhancing connections, and facilitating leak sealing, thereby improving construction convenience and initial sealing effectiveness to some extent. However, these improvements do not address the fundamental working mode of the sealing device. Regardless of structural optimization, maintaining sealing pressure still relies on the passive compression and rebound of the gasket itself. When the segment joints open or shift due to uneven ground settlement, seismic loads, or disturbances from nearby construction, the compression of the gasket decreases, contact stress declines, and waterproofing capability diminishes. After long-term service, the gasket material inevitably undergoes stress relaxation and permanent compression deformation, further exacerbating the risk of seal failure. In other words, existing sealing devices lack the ability to actively adapt to joint deformation changes and cannot proactively generate restoring force to compensate for contact stress loss after deformation occurs.

[0008] Therefore, developing a sealing device that can adapt to joint deformation and maintain effective sealing force over a long period of time is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0009] The purpose of this invention is to provide an adaptive sealing device and construction method for shield tunnel segment joints based on SMA, so as to solve the technical problem that existing sealing devices cannot actively compensate for contact stress loss after joint deformation or material relaxation.

[0010] To achieve the above objectives, the present invention provides the following technical solution: an adaptive sealing device for shield tunnel segment joints based on SMA, wherein the adaptive sealing device is a strip-shaped composite gasket arranged longitudinally along the segment joint and embedded in the groove of the segment sidewall, the strip-shaped composite gasket comprising, from the inside to the outside:

[0011] The skeleton layer is integrally formed by additive manufacturing of shape memory alloy. The skeleton layer has a preset three-dimensional waveform and its internal structure is an asymmetric mesh skeleton with a gradient change along the thickness direction.

[0012] The intermediate energy-absorbing layer, which covers the outside of the skeleton layer, is made of a porous elastic material;

[0013] The outer wear-resistant layer is formed on the outer surface of the middle energy-absorbing layer.

[0014] Furthermore, the asymmetric grid skeleton is divided into a compression zone and a tension zone along the radial direction of the joint. The compression zone is close to the joint sealing surface and is composed of diamond-shaped grid supports arranged in layers along the radial direction. The diameter of the supports in the same layer is equal, and the diameter of the supports in each layer increases from the sealing surface to the trench direction. The acute angle of each layer of diamond grid decreases. The tension zone is close to the bottom wall of the segment trench and is composed of a wave-shaped filament array arranged in parallel along the longitudinal direction of the joint. Ball joints are provided at the crests and troughs of each wave-shaped filament, and adjacent filaments are connected at the ball joints by X-shaped cross connecting ribs.

[0015] Furthermore, the number of layers of diamond-shaped grid supports in the compression zone is 3 to 5, the diameter of adjacent layers of supports increases by 10% to 15%, and the acute angle of the diamond decreases from 60° to 30° from the sealing surface to the groove direction.

[0016] Furthermore, in the tension zone, the diameter of the wavy filament is 0.2mm to 0.3mm, the wavy period length is 5mm to 8mm, the wave amplitude is 1mm to 2mm, the diameter of the ball joint is 1.5 to 2 times the diameter of the filament, and the diameter of the X-shaped cross connecting rib is 0.1mm to 0.2mm.

[0017] Furthermore, the three-dimensional waveform of the skeleton layer is a continuous or discontinuous W-shaped, M-shaped or sine wave, and its amplitude and wavelength are topology optimized according to the allowable deformation of the joint design of the target tube segment.

[0018] Furthermore, the three-dimensional waveform of the skeleton layer is distributed in a spindle shape along the longitudinal direction of the joint, with small amplitude at both ends and large amplitude in the middle, and the wavelength gradually increases from both ends to the middle.

[0019] Furthermore, the outer wear-resistant layer is a PTFE and molybdenum disulfide blended modified coating or an ultra-high molecular weight polyethylene film with a thickness of 0.1 mm to 0.3 mm and a friction coefficient of less than 0.08.

[0020] Furthermore, the porous elastic material of the intermediate energy-absorbing layer is open-cell polyurethane foam or open-cell EPDM rubber foam, with a porosity of 40% to 55% and an average pore size of 0.3 mm to 0.8 mm.

[0021] Furthermore, the shape memory alloy is a Ni-Ti binary alloy or a Ni-Ti-Nb ternary alloy.

[0022] The construction method of the shield tunnel segment joint adaptive sealing device based on SMA includes the following steps:

[0023] S1: Pre-fabrication preparation: According to the design parameters, the skeleton layer is integrally formed using additive manufacturing technology; an intermediate energy-absorbing layer is formed on the outside of the skeleton layer through injection molding or foaming process; and an outer edge wear-resistant layer is formed on the outer surface to obtain the finished strip-shaped composite pad.

[0024] S2: Groove treatment, cleaning and drying are carried out in the pre-set grooves on the side wall of the shield tunnel segment, and an interface adhesive is applied if necessary;

[0025] S3: Device installation: Embed the strip-shaped composite pad longitudinally into the groove on the side wall of the segment along the joint, ensuring that the compression zone faces the joint sealing surface and the tension zone faces the bottom wall of the groove.

[0026] S4: Segment assembly. The segments are assembled according to the conventional shield tunneling process. Joint compression causes the adaptive sealing device to generate a preset deformation. When the joints open or shift during service, the shape memory alloy of the skeleton layer uses the superelastic effect or shape memory effect to drive the structure to recover and maintain the sealing pressure.

[0027] S5: Acceptance inspection. Check that the sealing device is installed in the correct position and is free from warping. Complete the joint sealing.

[0028] Compared with existing technologies, the adaptive sealing device and construction method for shield tunnel segment joints based on SMA provided by this invention, on the one hand, actively generates restoring force to compensate for contact stress loss when the joint opens or shifts due to the unique superelastic effect of the shape memory alloy skeleton layer, thus solving the problem of passive response and stress relaxation leading to sealing failure of traditional sealing gaskets after long-term service. On the other hand, through the asymmetric gradient structure design of the variable diameter rhomboid grid in the compression zone and the wavy filaments in the tension zone, differentiated stress matching between the sealing surface side of the joint and the bottom wall side of the trench is achieved. Moreover, the skeleton layer is distributed in a spindle shape along the longitudinal direction of the joint with small amplitude at both ends and large amplitude in the middle, further adapting to the actual stress characteristics of large deformation in the middle and small deformation at both ends of the segment joint, significantly improving the adaptive capability and waterproof reliability of the sealing device throughout its entire life cycle. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this invention. For those skilled in the art, other drawings can be obtained based on these drawings.

[0030] Figure 1 This is a schematic diagram of the shield tunnel segment assembly structure of the present invention;

[0031] Figure 2 This is a schematic diagram showing the installation positions of the shield tunnel segments and strip-shaped composite pads of the present invention;

[0032] Figure 3 This is a schematic diagram of the layered structure of the strip-shaped composite pad in Embodiment 1 of the present invention;

[0033] Figure 4This is a schematic diagram of the asymmetric mesh skeleton in Embodiment 2 of the present invention.

[0034] Explanation of reference numerals in the attached figures:

[0035] 1. Strip-shaped composite pad; 2. Skeleton layer; 3. Middle energy-absorbing layer; 4. Outer wear-resistant layer; 5. Asymmetric grid skeleton; 501. Compression zone; 502. Tension zone. Detailed Implementation

[0036] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.

[0037] As attached Figure 1 To be continued Figure 3 As shown:

[0038] Example 1:

[0039] The present invention provides an adaptive sealing device for shield tunnel segment joints based on SMA. The adaptive sealing device is a strip-shaped composite pad 1 arranged longitudinally along the segment joint and embedded in the groove of the segment side wall. The strip-shaped composite pad 1 includes a skeleton layer 2, an intermediate energy-absorbing layer 3 and an outer wear-resistant layer 4 from the inside to the outside.

[0040] 1. In one embodiment of the present invention, the skeleton layer 2 is integrally formed by shape memory alloy through additive manufacturing, and the skeleton layer 2 has a preset three-dimensional waveform.

[0041] 2. In one embodiment of the present invention, the intermediate energy-absorbing layer 3 covers the outer side of the skeleton layer 2 and is made of porous elastic material. It is used to absorb the impact energy generated during the assembly and operation of the tunnel segments, and at the same time provides an elastic support environment for the skeleton layer 2.

[0042] 3. In one embodiment of the present invention, the outer wear-resistant layer 4 is formed on the outer surface of the intermediate energy-absorbing layer 3.

[0043] 4. In one embodiment of the present invention, the three-dimensional waveform of the skeleton layer 2 is a continuous or discontinuous W-shaped, M-shaped or sine wave, and its amplitude and wavelength are topologically optimized according to the allowable deformation of the joint design of the target tube segment.

[0044] 5. In one embodiment of the present invention, the three-dimensional waveform of the skeleton layer 2 is distributed in a spindle shape with small amplitude at both ends and large amplitude in the middle along the longitudinal direction of the joint, and the wavelength gradually increases from both ends to the middle.

[0045] 6. In one embodiment of the present invention, the outer wear-resistant layer 4 is a PTFE and molybdenum disulfide blended modified coating or an ultra-high molecular weight polyethylene film with a thickness of 0.1 mm to 0.3 mm and a friction coefficient of less than 0.08.

[0046] 7. In one embodiment of the present invention, the porous elastic material of the intermediate energy-absorbing layer 3 is an open-cell polyurethane foam or an open-cell EPDM rubber foam, with a porosity of 40% to 55% and an average pore size of 0.3 mm to 0.8 mm.

[0047] 8. In one embodiment of the present invention, the shape memory alloy is a Ni-Ti binary alloy or a Ni-Ti-Nb ternary alloy.

[0048] Working Principle: In Example 1, a three-dimensional waveform skeleton layer 2 made of shape memory alloy is used. This layer combines the low-friction characteristics of the outer wear-resistant layer 4 with the buffering energy absorption effect of the middle energy-absorbing layer 3. During segment assembly, the strip-shaped composite gasket 1 is compressed and embedded into the groove. When the segment joints open or shift due to operational loads, the SMA skeleton layer 2 utilizes its hyperelastic effect to actively generate a restoring force, driving the sealing gasket to rebound to compensate for contact stress loss, thereby maintaining the joint sealing pressure. The spindle-shaped waveform distribution allows the sealing device to adapt to the non-uniform longitudinal deformation characteristics of the joint, with a large amplitude in the middle and small amplitude at both ends, precisely matching the actual stress state of the segment joint where deformation is large in the middle and small at both ends.

[0049] As attached Figure 1 To be continued Figure 4 As shown:

[0050] Example 2:

[0051] This embodiment is basically the same as the previous embodiment. The internal structure of the skeleton layer 2 is an asymmetric mesh skeleton 5 with a gradient change along the thickness direction. The asymmetric mesh skeleton 5 is divided into a compression zone 501 and a tension zone 502 along the joint radial direction. The compression zone 501 is close to the joint sealing surface. The compression zone 501 is composed of diamond mesh pillars arranged layer by layer along the radial direction. The pillar diameters in the same layer are equal. From the sealing surface to the groove direction, the pillar diameters of each layer increase layer by layer, and the acute angle of each layer of diamond mesh decreases layer by layer. The tension zone 502 is close to the bottom wall of the segment groove. The tension zone 502 is composed of a wave-shaped filament array arranged parallel along the longitudinal direction of the joint. Ball joints are provided at the crests and troughs of each wave-shaped filament. Adjacent filaments are connected at the ball joints by X-shaped cross connecting ribs.

[0052] 1. In one embodiment of the present invention, the number of layers of rhomboid grid support pillars in the compression zone 501 is 3 to 5, the increase in diameter of adjacent layers of support pillars is 10% to 15%, and the acute angle of the rhombus decreases from 60° to 30° from the sealing surface to the groove direction.

[0053] 2. In one embodiment of the present invention, the diameter of the wavy filament in the tension zone 502 is 0.2mm to 0.3mm, the wave period length is 5mm to 8mm, the wave amplitude is 1mm to 2mm, the diameter of the ball joint is 1.5 to 2 times the diameter of the filament, and the diameter of the X-shaped cross connecting rib is 0.1mm to 0.2mm.

[0054] Working Principle: During service, the side of the segment joint sealing device near the joint sealing surface mainly bears compressive loads, while the side near the bottom wall of the trench mainly bears tensile and shear loads. Traditional uniform cross-section grid structures cannot simultaneously meet the differentiated mechanical requirements of both sides. Even with the three-dimensional waveform skeleton layer 2 of Example 1, it cannot achieve precise mechanical matching for the compression and tension sides. Therefore, Example 2, based on Example 1, constructs the skeleton layer 2 internally as an asymmetric grid skeleton 5 with a gradient change along the thickness direction: the compression zone 501 adopts a variable diameter rhombic grid structure, with the support diameter increasing layer by layer and the acute angle of the rhombus decreasing layer by layer, forming a stiffness gradient along the compression direction, so that the compressive stress is transferred and dispersed layer by layer from the sealing surface to the bottom wall of the trench, avoiding stress concentration; the tension zone 502 adopts a wave-shaped filament array combined with ball joints and X-shaped cross connecting ribs. The wave shape gives the filaments a large tensile deformation capacity, the ball joints serve as stress release nodes to prevent local fracture, and the X-shaped connecting ribs enhance the cooperative deformation capacity between the filaments. When the joint opens, the 502 filaments in the tension zone are stretched and actively generate shrinkage recovery force using the superelasticity of the SMA; when the joint shifts, the ball joint and the X-shaped rib jointly bear the shear load, ensuring structural integrity. Through the above asymmetric gradient design, the sealing device achieves differentiated mechanical properties of high stiffness and compressive strength on the compression side and high flexibility and tensile strength on the tension side, significantly improving the comprehensive adaptive capability of the joint to multidimensional deformation (compression, tension, and shear).

[0055] In conjunction with Embodiments 1 and 2 above, the present invention also provides a construction method for an adaptive sealing device for tunnel segment joints based on SMA, comprising the following steps:

[0056] S1: Pre-fabrication preparation: According to the design parameters, the skeleton layer 2 is integrally formed using additive manufacturing technology; an intermediate energy-absorbing layer 3 is formed on the outside of the skeleton layer 2 through injection molding or foaming process; and an outer edge wear-resistant layer 4 is formed on the outer surface to obtain the finished strip-shaped composite pad 1.

[0057] S2: Groove treatment, cleaning and drying are carried out in the pre-set grooves on the side wall of the shield tunnel segment, and an interface adhesive is applied if necessary;

[0058] S3: Device installation: Insert the strip-shaped composite pad 1 longitudinally into the groove on the side wall of the tube segment along the joint, ensuring that the compression zone 501 faces the joint sealing surface and the tension zone 502 faces the bottom wall of the groove.

[0059] S4: Segment assembly. Segments are assembled according to the conventional shield tunneling construction process. Joint compression causes the adaptive sealing device to produce a preset deformation. When the joints open or shift during service, the shape memory alloy of the skeleton layer 2 uses the superelastic effect or shape memory effect to drive the structure to recover and maintain the sealing pressure.

[0060] S5: Acceptance inspection. Check that the sealing device is installed in the correct position and is free from warping. Complete the joint sealing.

[0061] The foregoing has only described certain exemplary embodiments of the present invention by way of illustration. Undoubtedly, those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the foregoing drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A shield tunnel segment joint adaptive sealing device based on SMA, wherein the adaptive sealing device is a strip-shaped composite gasket (1) arranged longitudinally along the segment joint and embedded in the groove of the segment sidewall, characterized in that, The strip-shaped composite pad (1) comprises, from the inside out: The skeleton layer (2) is integrally formed by additive manufacturing of shape memory alloy. The skeleton layer (2) has a preset three-dimensional waveform and its internal structure is an asymmetric mesh skeleton (5) with a gradient change along the thickness direction. The intermediate energy-absorbing layer (3) is wrapped around the outside of the skeleton layer (2) and is made of porous elastic material; The outer wear-resistant layer (4) is formed on the outer surface of the middle energy-absorbing layer (3).

2. The adaptive sealing device for shield tunnel segment joints based on SMA according to claim 1, characterized in that, The asymmetric mesh skeleton (5) is divided into a compression zone (501) and a tension zone (502) along the radial direction of the joint. The compression zone (501) is close to the joint sealing surface and is composed of diamond mesh pillars arranged in layers along the radial direction. The tension zone (502) is close to the bottom wall of the segment groove and is composed of a wave-shaped filament array arranged in parallel along the longitudinal direction of the joint. Each wave-shaped filament has a ball joint at the crest and trough.

3. The SMA-based adaptive sealing device for shield tunnel segment joints according to claim 2, characterized in that, The number of layers of rhomboid grid supports in the compression zone (501) is 3 to 5, the diameter of adjacent support layers increases by 10% to 15%, and the acute angle of the rhomboid decreases from 60° to 30° from the sealing surface to the groove direction.

4. The adaptive sealing device for shield tunnel segment joints based on SMA according to claim 2, characterized in that, The diameter of the wavy filament in the stretching zone (502) is 0.2mm to 0.3mm, the wave period length is 5mm to 8mm, the wave amplitude is 1mm to 2mm, and the diameter of the ball joint is 1.5 to 2 times the diameter of the filament.

5. The adaptive sealing device for shield tunnel segment joints based on SMA according to claim 1, characterized in that, The three-dimensional waveform of the skeleton layer (2) is a continuous or discontinuous W-type, M-type or sine wave.

6. The adaptive sealing device for shield tunnel segment joints based on SMA according to claim 1, characterized in that, The porous elastic material of the intermediate energy-absorbing layer (3) is open-cell polyurethane foam or open-cell EPDM rubber foam.

7. The SMA-based adaptive sealing device for shield tunnel segment joints according to claim 5, characterized in that, The three-dimensional waveform of the skeleton layer (2) is distributed in a spindle shape with small amplitude at both ends and large amplitude in the middle along the longitudinal direction of the joint, and the wavelength gradually increases from both ends to the middle.

8. The adaptive sealing device for shield tunnel segment joints based on SMA according to claim 1, characterized in that, The outer wear-resistant layer (4) is a PTFE and molybdenum disulfide blended modified coating or an ultra-high molecular weight polyethylene film.

9. The construction method of the SMA-based adaptive sealing device for shield tunnel segment joints as described in any one of claims 1-8, characterized in that, Includes the following steps: S1: Pre-fabrication preparation: According to the design parameters, the skeleton layer (2) is integrally formed by additive manufacturing technology; an intermediate energy-absorbing layer (3) is formed on the outside of the skeleton layer (2) by injection molding or foaming process; and an outer edge wear-resistant layer (4) is formed on the outer surface to obtain the finished strip-shaped composite pad (1); S2: Trench treatment, cleaning and drying treatment is carried out in the pre-set trenches on the side wall of the shield tunnel segment; S3: Install the device by embedding the strip-shaped composite pad (1) longitudinally into the groove on the side wall of the tube segment along the joint, ensuring that the compression zone (501) faces the joint sealing surface and the tension zone (502) faces the bottom wall of the groove. S4: Segment assembly, the segments are assembled according to the conventional shield tunneling process, and the joint compression causes the adaptive sealing device to produce a preset deformation; when the joints open or shift during the service period, the skeleton layer (2) shape memory alloy uses the superelastic effect or shape memory effect to drive the structure to recover and maintain the sealing pressure. S5: Acceptance inspection. Check that the sealing device is installed in the correct position and is free from warping. Complete the joint sealing.

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