Piezoelectric driving reset bolt joint for fabricated subway station

Abstract

The application provides a piezoelectric driving reset bolt joint for a fabricated subway station, which comprises a shape memory alloy bolt and a nut matched with the shape memory alloy bolt; reset mechanisms and fixed points are arranged at two ends of the shape memory alloy bolt respectively, and tensile wire displacement meters are connected to the reset mechanisms and the fixed points at the two ends respectively; a piezoelectric ceramic element is arranged on the shape memory alloy bolt, the piezoelectric ceramic element is connected with the reset mechanisms through wires, and the reset mechanisms are in an energy storage state through the piezoelectric ceramic element; a prefabricated groove is formed on the shape memory alloy bolt. The shape memory alloy bolt is used for connecting the joint of the fabricated subway station, which can adapt to the deformation change of the joint, and the shape memory alloy bolt has high reusability.

Description

Technical Field

[0001] This invention relates to the field of prefabricated subway station engineering technology, and specifically to a piezoelectrically driven reset bolt connector for prefabricated subway stations. Background Technology

[0002] Prefabricated subway stations are constructed from reinforced concrete components, and the joints are the weakest points in the overall structural load-bearing capacity. During subway operation, due to the influence of external loads, the joints of prefabricated subway stations buried underground may deform and crack, seriously affecting the safe operation of the subway. Currently, the publicly disclosed types of joints in prefabricated subway stations include: wedge bolt type joints in the connection nodes of prefabricated subway station structures and their components disclosed in announcement number [CN212612628U]; mortise and tenon single bolt type joints in the design and construction method of partially prefabricated subway station structures disclosed in announcement number [CN110512647B]; and mortise and tenon combined bolt joints in the prefabricated subway station structure integrating building space structure disclosed in announcement number [CN112502186A]. These joints all use ordinary metal bolts as connecting components. Once the joint undergoes significant deformation, the bolts will yield, making subsequent repair and reinforcement very difficult.

[0003] Shape memory alloys (MMEs) exhibit strong deformation recovery capabilities under external temperature stimuli. In other structural fields, there are already cases of using MME bolts instead of ordinary bolts. For example, announcement number [CN109989481A] discloses a bolted joint for timber beams and columns reinforced with MMEs and its fabrication method, which uses MME-reinforced MME bolts to reinforce timber beams and columns. Another example is announcement number [CN114547805A], which discloses a flexible MME ring joint for shield tunnels and its design method, using a combination of MME rings and ordinary bolts as the ring bolts for shield tunnels. Yet another example is announcement number [CN210239290U], which discloses a self-resetting energy-dissipating section using MMEs and expanded-hole bolts as the resetting connector for frame beams. However, the above does not consider the conditions for shape memory alloy bolts to reset, which require controlling the temperature of the bolt surface. Since prefabricated subway stations are buried underground, the bolts at the joints are usually encased in concrete, making it impossible to achieve bolt reset using conventional heating methods. Furthermore, bolt deformation is not easily detected. Therefore, when using shape memory alloy bolts in prefabricated subway stations, a suitable driving method is needed to achieve automatic bolt reset. Summary of the Invention

[0004] The purpose of this invention is to provide a method for achieving self-resetting of bolts in prefabricated subway stations without the need for manual heating, namely, a piezoelectrically driven reset bolt connector for prefabricated subway stations.

[0005] Therefore, the present invention adopts the following technical solution:

[0006] A piezoelectrically driven reset bolt connector for prefabricated subway stations includes a shape memory alloy bolt and a nut that mates with the shape memory alloy bolt. The shape memory alloy bolt has a reset mechanism and a fixing point at each end, and a tension wire displacement gauge connected to the reset mechanism and the fixing point at each end. A piezoelectric ceramic element is disposed on the shape memory alloy bolt, and the piezoelectric ceramic element is connected to the reset mechanism via a wire. The reset mechanism is in an energy storage state through the piezoelectric ceramic element. A pre-fabricated groove is formed on the shape memory alloy bolt, and the tension wire displacement gauge is disposed within the pre-fabricated groove. Through the change in the state of the tension wire displacement gauge, the reset mechanism switches to a heating and reset state for the shape memory alloy bolt.

[0007] Furthermore: the reset mechanism includes a storage battery and its storage battery controller; the reset mechanism also includes a contact heating rod; the storage battery and its storage battery controller are mounted on the nut and electrically connected to the contact heating rod; the shape memory alloy bolt has a first pre-set hole on it that is connected and engaged with the contact heating rod.

[0008] Furthermore: the tension wire displacement gauge includes a tension wire and a displacement monitor; the displacement monitor is connected to the reset mechanism through the wire; one end of the tension wire is connected to the fixed point, and the other end cooperates with the displacement monitor.

[0009] Furthermore, the shape memory alloy bolt has a second pre-drilled hole, and the fixing point is detachably set in the second pre-drilled hole.

[0010] Furthermore, the bolt joint is disposed between adjacent concrete components, and each adjacent concrete component is provided with a bolt hand hole that mates with the same bolt joint.

[0011] Furthermore, the bolt hand hole is inclined and embedded in the concrete component, thereby creating a placement space for the bolt hand hole away from the part of the concrete component that is in contact with it.

[0012] Furthermore, the shape memory alloy bolt is provided with a washer located between the nut and the end wall of the bolt hand hole.

[0013] Furthermore: the piezoelectric ceramic element is disposed at the joint between adjacent concrete components, or at the point where the concrete component and the nut are fitted together; the two end faces of the piezoelectric ceramic element are pressure-bearing portions that mate with the mating surface.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] This invention uses shape memory alloy bolts to connect prefabricated subway station joints, which can adapt to deformation changes at the joints. The shape memory alloy bolts have a high reusability rate. By using piezoelectric drive to reset the shape memory alloy bolts, the shape of the shape memory alloy bolts is automatically adjusted according to the displacement changes of the joints. Thus, the bolts can be effectively reset without manual measurement and heating reset. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0017] Figure 2 This is a schematic diagram of the pre-drilled slots on the shape memory metal bolt of the present invention;

[0018] Figure 3 This is a front view schematic diagram of the entire invention;

[0019] Figure 4 This is a schematic diagram of the installation location of the present invention in a subway station.

[0020] The markings in the attached diagram are as follows: 1-shape memory metal bolt; 2-nut; 3-washer; 4-piezoelectric ceramic element; 5-stretch wire; 6-fixing point; 7-displacement monitor; 8-battery controller; 9-contact heating rod; 10-wire; 11-prefabricated slot; 12-second prefabricated hole; 13-first prefabricated hole; 14-bolt hand hole. Detailed Implementation

[0021] The present invention will be further described below with reference to the accompanying drawings and embodiments, but this should not be construed as limiting the present invention.

[0022] like Figure 1-3 As shown, this embodiment provides a deformation self-resetting bolt joint. This bolt joint can self-heat and reset itself after deformation, thereby effectively controlling the displacement between adjacent concrete components caused by frequent vibration and resetting the concrete components.

[0023] Specifically, the bolt joint includes a shape memory alloy bolt 1 and a nut 2 that mates with the shape memory alloy bolt 1; a reset mechanism and a fixing point 6 are respectively provided at both ends of the shape memory alloy bolt 1, and a tension wire displacement gauge is respectively connected to the reset mechanism and the fixing point 6 at both ends; a piezoelectric ceramic element 4 is provided on the shape memory alloy bolt 1, and the piezoelectric ceramic element 4 is connected to the reset mechanism through a wire 10, and the reset mechanism is in an energy storage state through the piezoelectric ceramic element 4; a pre-made groove 11 is opened on the shape memory alloy bolt 1, and the tension wire displacement gauge is set in the pre-made groove 11. Through the state change of the tension wire displacement gauge, the reset mechanism switches to form a heating reset state for the shape memory alloy bolt 1.

[0024] The piezoelectric ceramic element 4 has a through-hole for mounting and disassembly on the shape memory alloy bolt 1. During operation of the prefabricated subway station, the piezoelectric ceramic element 4 converts vibration energy into electrical energy, thus pre-collecting energy while the shape memory alloy bolt 1 is under load. This energy is then stored in conjunction with a battery to provide sufficient heating and resetting energy for subsequent deformation of the shape memory alloy bolt 1. The outer surface of the piezoelectric ceramic element 4 is connected to the side of the battery via a wire 10, which is positioned along the axis of the nut 2 on its outer circumference to ensure the shortest possible direct wiring.

[0025] like Figure 2 As shown, the reset mechanism includes a battery and its battery controller 8; the reset mechanism also includes a contact heating rod 9; the battery and its battery controller 8 are mounted on the nut 2 and electrically connected to the contact heating rod 9; the shape memory alloy bolt 1 has a first pre-set hole 13 on it that is connected and cooperates with the contact heating rod 9.

[0026] like Figure 2 As shown, the shape memory alloy bolt 1 has a second pre-drilled hole 12, and the fixing point 6 is detachably installed in the second pre-drilled hole 12. In this embodiment, the second pre-drilled hole 12 is installed in the pre-made groove 11 so that the drawing wire 5 can be fully inserted into the pre-made groove 11.

[0027] In this embodiment, the nut 2 is made of metal, and the battery controller 8 and displacement monitor 7 are bonded to the nut 2 using epoxy resin. The fixing point 6 is a rivet, and the rivet should ideally not protrude from the pre-made groove 11 after entering the second pre-set hole 12.

[0028] like Figure 1 and 3As shown, the tension wire displacement gauge includes a tension wire 5 and a displacement monitor 7. The displacement monitor 7 is connected to a battery controller 8 within a reset mechanism via a wire 10. One end of the tension wire 5 is connected to a fixed point 6, and the other end engages with the displacement monitor 7. When the tension wire 5 moves, it extends and contracts. A spring inside the displacement monitor 7 ensures that the tension of the tension wire 5 remains constant. During displacement, an internal incremental encoder outputs an electrical signal proportional to the distance the tension wire 5 moves. By measuring this output signal, the displacement, direction, or speed of the moving object can be determined.

[0029] In this embodiment, the displacement monitor 7 uses a displacement sensor, which senses the displacement of the tension wire 5 through an internal incremental encoder, thereby controlling the battery controller 8 to turn the battery on or off. Signal transmission between the battery and its controller 8, the displacement monitor 7, the piezoelectric ceramic element 4, and the battery and its controller 8 is achieved via wires 10.

[0030] like Figure 4 As shown, this embodiment also provides a concrete component connection structure that can accommodate bolt joints. Adjacent concrete components have bolt manholes 14 at their mating points that mate with the bolt joints. The bolt manholes 14 are inclined and embedded within the concrete components. The bolt manholes 14 on both sides are interconnected. By inserting shape memory alloy bolts 1 inclined into the bolt manholes 14 on both sides, a connection is formed between the adjacent concrete components. The portion of the bolt manholes 14 away from the mating point of the concrete components can be used to create placement space. The overall structure of the prefabricated subway station is formed by splicing concrete components, especially those near the shield tunneling shaft (the subway station's entrance / exit). Shape memory alloy bolts 1 connect each joint of the prefabricated subway station to ensure the stability of the overall structure and to quickly and effectively reset the shape memory alloy bolts 1 when deformation occurs due to excessive vibration, thus ensuring the connection strength of the overall structure.

[0031] The bolt handholes 14 on both sides of the inclined concrete component are aligned axially, and the placement space is wedge-shaped within the concrete component. This placement space covers the bolt handholes 14 and is larger than their area. The placement space can accommodate the nut 2 and the end of the shape memory alloy bolt 1, and more importantly, it can accommodate the components within the reset mechanism, thus preventing them from protruding from the surface of the concrete component and better housing all parts of the shape memory alloy bolt 1 within the concrete component.

[0032] The piezoelectric ceramic element 4 is disposed at the joint between adjacent concrete components or at the point where the concrete component and the nut 2 are fitted together; the two end faces of the piezoelectric ceramic element 4 are pressure-bearing portions that mate with the mating surface. Ideally, the piezoelectric ceramic element 4 is disposed between the washer 3 and the nut 2. The washer 3 effectively protects the piezoelectric ceramic element 4, and the diameter of the washer 3 is larger than the diameter of the piezoelectric ceramic element 4, thus providing more comprehensive protection and reducing wear on the piezoelectric ceramic element 4.

[0033] In this embodiment, the structure is applicable to various prefabricated subway station joints, and the size of the shape memory alloy bolt 1 can be adjusted according to actual needs. Furthermore, the shape memory alloy bolt 1 is deployed in the subway station joint using an iron-based shape memory alloy, which has a high recovery stress, reaching a maximum of 400 MPa. Since prefabricated subway station structures are buried underground, they are susceptible to corrosion from groundwater. The iron-based shape memory alloy contains elements such as Cr, Ni, and Si, exhibiting strong corrosion resistance, thus improving the durability of the prefabricated subway station structure. The reset of the shape memory alloy bolt 1 is controlled by the signal from the displacement monitor 7, eliminating the need for constant monitoring of the bolt's stress state. Therefore, the entire process requires no manual control, and the shape memory alloy bolt 1 can be reused, exhibiting high efficiency, speed, and high reusability.

[0034] Please see Figure 1-4 The specific implementation method of shape memory alloy bolt 1 for connection and repositioning in prefabricated subway stations is as follows:

[0035] S1: Based on the burial depth and surrounding conditions of the prefabricated subway station, determine the diameter and length of the shape memory alloy bolt 1, and prefabricate the second pre-drilled hole 12 and the first pre-drilled hole 13 at both ends of the shape memory alloy bolt 1, and prefabricate the groove 11 in the middle.

[0036] S2: Place the drawing wire 5 in the pre-made groove 11, connect one end to the fixing point 6, and embed the rivet into the second pre-set hole 12. Connect the other end to the displacement monitor 7.

[0037] S3: Pass the shape memory alloy bolt 1 through the bolt hand hole 14, and put the washer 3 and nut 2 on the two ends near the concrete component surface respectively, as well as the washer 3, piezoelectric ceramic element 4 and nut 2;

[0038] S4: Epoxy resin is used to attach the battery, its battery controller 8 and displacement monitor 7 to the nut 2 on the reset mechanism side. The battery controller 8 and displacement monitor 7 are connected by wire 10, and the contact heating rod 9 is embedded into the first pre-drilled hole 13 of the shape memory alloy bolt 1.

[0039] When the shape memory alloy bolt 1 is reset, the mechanical energy collected by the piezoelectric ceramic element 4 during station operation is converted into electrical energy and stored in the battery through the wire 10. When the shape memory alloy bolt 1 is deformed, the tension wire 5 will also be displaced. The displacement monitor 7 transmits the sensed displacement change of the tension wire 5 to the battery controller 8. The battery controller 8 provides electrical energy to the contact heating rod 9, thereby controlling the contact heating rod 9 to release different amounts of heat energy to drive the shape memory alloy bolt 1 to reset. When the shape memory alloy bolt 1 returns to its original shape, the displacement signal generated by the tension wire 5 will be sent through the displacement monitor 7 to control the battery controller 8 to stop heating.

[0040] The above embodiments are merely preferred technical solutions of the present invention. Those skilled in the art should understand that modifications or substitutions to the technical solutions or parameters in the embodiments can be made without departing from the principles and essence of the present invention, and all such modifications or substitutions should be covered within the protection scope of the present invention.

Claims

1. A piezoelectrically driven reset bolt connector for prefabricated subway stations, the bolt connector comprising a shape memory alloy bolt (1) and a nut (2) cooperating with the shape memory alloy bolt (1); characterized in that: The shape memory alloy bolt (1) is provided with a reset mechanism and a fixing point (6) at both ends, and a tension wire displacement gauge connected to the reset mechanism and the fixing point (6) at both ends respectively; The shape memory alloy bolt (1) is provided with a piezoelectric ceramic element (4), and the piezoelectric ceramic element (4) is connected to the reset mechanism through a wire (10). The reset mechanism is in an energy storage state through the piezoelectric ceramic element (4). The shape memory alloy bolt (1) has a pre-made groove (11) and the stretch wire displacement gauge is set in the pre-made groove (11). Through the state change of the stretch wire displacement gauge, the reset mechanism switches to form a heating reset state for the shape memory alloy bolt (1). The reset mechanism includes a storage battery and its storage battery controller (8). The reset mechanism also includes a contact heating rod (9); The storage battery and its storage battery controller (8) are mounted on the nut (2) and electrically connected to the contact heating rod (9); The shape memory alloy bolt (1) has a first pre-set hole (13) on it that is connected and engaged with the contact heating rod (9). The stretch wire displacement gauge includes a stretch wire (5) and a displacement monitor (7); The displacement monitor (7) is connected to the reset mechanism via the wire (10); One end of the stretching wire (5) is connected to the fixed point (6), and the other end is connected to the displacement monitor (7).

2. The piezoelectrically driven reset bolt connector for prefabricated subway stations according to claim 1, characterized in that: The shape memory alloy bolt (1) has a second pre-set hole (12), and the fixing point (6) is detachably set in the second pre-set hole (12).

3. A piezoelectrically driven reset bolt connector for prefabricated subway stations according to claim 1, characterized in that: The bolt joint is provided between adjacent concrete members, and each of the adjacent concrete members is provided with a bolt hand hole (14) that mates with the same bolt joint.

4. A piezoelectrically driven reset bolt connector for prefabricated subway stations according to claim 3, characterized in that: The bolt hand hole (14) is inclined and embedded in the concrete member, so that the portion of the bolt hand hole (14) away from the part of the concrete member that is in contact with it forms a placement space.

5. A piezoelectrically driven reset bolt connector for prefabricated subway stations according to claim 3, characterized in that: The shape memory alloy bolt (1) is provided with a washer (3) located between the nut (2) and the side wall of the bolt hand hole (14).

6. A piezoelectrically driven reset bolt connector for prefabricated subway stations according to claim 3, characterized in that: The piezoelectric ceramic element (4) is disposed at the joint of the adjacent concrete component or at the joint between the concrete component and the nut (2); the two end faces of the piezoelectric ceramic element (4) are pressure-bearing parts that cooperate with the mating surface.

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