A connecting structure and construction method for connecting new and old bridges by using telescopic steel bars

Abstract

The present application belongs to the technical field of bridge engineering, and particularly relates to a connecting structure for splicing new and old bridges by using telescopic steel bars and a construction method. The present application provides a connecting structure for splicing new and old bridges by using telescopic steel bars, which comprises a steel bar unit, an internally threaded pipe body unit, and a tensile resistance block unit, so that: 1. the connecting structure has sufficient and appropriate tensile strength, avoiding excessive separation between the new and old bridges; 2. the connecting structure has sufficient and appropriate vertical load transmission capacity, thereby mainly protecting the old bridge with relatively low structural strength; 3. the connecting structure allows the new and old bridges to appropriately relatively displace in the vertical and longitudinal bridge directions, avoiding the "hard pulling" mode to damage the structures of the connecting structure and the new and old bridges.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of bridge engineering, and particularly relates to a connecting structure for widening new and old bridges by using telescopic steel bars and a construction method. BACKGROUND

[0002] The main construction contents of the widened new and old bridge project include reinforcing the old bridge, building the new bridge, and connecting the new and old bridges in the transverse direction. The main purpose of the project is to increase the number of lanes to meet the traffic demand.

[0003] On the other hand, the way of connecting the new and old bridges can be mainly divided into rigid connection and flexible connection according to the different connection strengths. The rigid connection generally uses a steel-concrete structure or a large steel frame structure, and its advantage is that the vehicle load on the old bridge can be maximally distributed to the new bridge, thereby fully protecting the old bridge. However, the rigid connection method is not suitable for the scenario where small relative displacement occurs between the new and old bridges, otherwise not only the connection structure will be damaged, but also the new and old bridges themselves will be greatly structurally damaged.

[0004] The telescopic steel bar method described above belongs to the flexible connection, and its functional characteristics are to allow small relative displacement between the new and old bridges and appropriately transfer the vehicle load. For example, the Chinese utility model patent with the authorization announcement number CN219604175U and the authorization announcement date of August 29, 2023 discloses a wet joint damping formwork for old bridge maintenance and widening, which belongs to the flexible connection method described above. The structure of the wet joint damping formwork includes a damping screw rod, a damping spring, a fixed nut, a cross beam, a pouring plate, and a fixed screw rod, the damping screw rod is arranged on the old bridge, the fixed screw rod is arranged on the new bridge, the damping spring is sleeved on the damping screw rod, the damping screw rod and the fixed screw rod are both installed with the fixed nut, the cross beam is provided with the pouring plate, and the cross beam is provided with the pouring plate.

[0005] The wet joint damping formwork in the utility model patent has the advantages that by arranging the damping structure on the old bridge side, the damage of the internal structure of the concrete caused by vibration is reduced under the condition that the old bridge is in use, and the pouring quality of the joint concrete is ensured.

[0006] However, when the wet joint damping formwork is used as a flexible connection structure for widening the new and old bridges, at least the following two deficiencies exist, which are also the technical problems to be solved by the present application, namely:

[0007] Firstly, the effective connection position of the structure is concentrated on the upper part of the new and old bridges, so it cannot fully pull the new and old bridges in the transverse direction, and when the new and old bridges have a large mutual trend of moving away in the transverse direction, the wet joint damping formwork is easy to be torn;

[0008] Second, even if it is a flexible connection structure, its ability to properly transfer vehicle load is still too low, and the vehicle load on the old bridge cannot be fully transferred to the new bridge, and the new bridge cannot fully share the pressure on the old bridge. When the vehicle load on the old bridge is relatively large, the wet joint damping template itself is prone to vertical misalignment and fracture, or the connection position between the new and old bridges is disconnected.

[0009] Therefore, in summary, there is an urgent need for a new and old bridge flexible widening structure that fully combines the transverse bridge tensile function, vertical load transfer sharing function, and relative displacement function in the vertical and longitudinal bridge directions. SUMMARY

[0010] The present application provides a connection structure for widening new and old bridges with telescopic steel rods, which includes a steel rod unit, an internally threaded pipe body unit, and a tensile resistance block unit, so that: 1. The connection structure has sufficient and appropriate tensile strength to prevent the new and old bridges from moving too far apart; 2. The connection structure has sufficient and appropriate vertical load transfer capacity, thereby mainly protecting the old bridge with relatively low structural strength; 3. The connection structure allows the new and old bridges to have appropriate relative displacement in the vertical and longitudinal bridge directions, avoiding "hard pull" damage to the structure itself and the new and old bridge structures.

[0011] In addition, the present application also provides a construction method for the above connection structure, which includes the following steps in sequence: installing a fixed inclined block in the internally threaded pipe, placing a movable inclined block in the internally threaded pipe, rotating and installing a first cylindrical rod body on the internally threaded pipe until the cylindrical rod body clamps the fixed inclined block, connecting the movable inclined block and a second cylindrical rod body. At this point, the entire tensile structure in the connection structure is complete.

[0012] The technical solution adopted by the present application to solve the above problems is: a connection structure for widening new and old bridges with telescopic steel rods, including a steel rod unit for connecting the bridge web, an internally threaded pipe body unit for screwing and sleeving two adjacent steel rod units at both ends, and a tensile resistance block unit arranged in the internally threaded pipe body unit and connecting the steel rod unit.

[0013] A further preferred technical solution is that the steel rod unit includes a cylindrical rod body, and a rod thread segment arranged at one end position of the cylindrical rod body and used for connecting the internally threaded pipe body unit.

[0014] A further preferred technical solution is that the steel rod unit further includes an inclined surface arranged at the other end position of the cylindrical rod body and used for connecting the bridge web.

[0015] A further preferred technical solution is that the internally threaded pipe body unit includes an internally threaded pipe for screwing and sleeving two adjacent cylindrical rod bodies at both ends.

[0016] Further preferred technical solutions are that the anti-tension blocking block unit comprises fixed inclined blocks arranged in the inner threaded pipe, and movable inclined blocks arranged on the end face of the cylindrical rod body and used for clamping the fixed inclined blocks when the cylindrical rod body is pulled out.

[0017] Further preferred technical solutions are that the anti-tension blocking block unit further comprises threaded segments arranged on the fixed inclined blocks and used for screwing the inner threaded pipe, and arc-shaped connecting strips arranged between two adjacent fixed inclined blocks in the circumferential direction.

[0018] Further preferred technical solutions are that one end of the rod-on-thread segment is arranged on the cylindrical rod body and on the end face of the fixed inclined block.

[0019] Further preferred technical solutions are that the anti-tension blocking block unit further comprises radial fixing grooves arranged on the fixed inclined blocks; and the inner threaded pipe unit further comprises mounting holes arranged on the inner threaded pipe, and fixing bolts arranged on the mounting holes and connected to the radial fixing grooves.

[0020] Further preferred technical solutions are that the anti-tension blocking block unit further comprises connecting studs arranged on the movable inclined blocks; and the steel rod unit further comprises threaded grooves arranged on the end face of the cylindrical rod body and used for mounting the connecting studs.

[0021] A construction method of a connecting structure for widening old and new bridges by using telescopic steel rods, sequentially comprising the following steps:

[0022] S1, rotating and installing the fixed inclined blocks in the inner threaded pipe;

[0023] S2, putting the movable inclined blocks into the inner threaded pipe;

[0024] S3, rotating and installing the first cylindrical rod body on the inner threaded pipe until the cylindrical rod body clamps the fixed inclined blocks;

[0025] S4, connecting the movable inclined blocks and the second cylindrical rod body. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 It is a schematic diagram of the position structure of the present application.

[0027] Figure 2 It is a schematic diagram of the first mode of realizing the anti-compression effect of the anti-tension blocking block unit in the present application.

[0028] Figure 3The second mode of realizing the compression resistance effect of the anti-tension resistance block unit in the application.

[0029] Figure 4 The structure of the internal thread pipe body unit in the application.

[0030] Figure 5 The fastening mode of the existing clamping nut if the cylindrical rod body is not clamped and fixed with the inclined surface block in the application.

[0031] Figure 6 The position and shape of the arc-shaped connecting strip in the application.

[0032] Figure 7 The position and shape of the threaded segment and the radial fixing groove in the application.

[0033] Figure 8 The shape of the first steel rod unit in the application.

[0034] Figure 9 The shape of the second steel rod unit in the application.

[0035] Figure 10 The position of the connecting stud and the threaded groove in the application.

[0036] Figure 11 The position and shape of the web connecting plate and the expansion bolt in the application.

[0037] Figure 12 The installation position of the connecting structure on the new and old bridge in the application.

[0038] In the figure, the meanings of the respective marks are as follows:

[0039] Bridge web a, bottom plate b, face plate c, web connecting plate d, expansion bolt e, clamping nut f;

[0040] Steel rod unit 1, internal thread pipe body unit 2, anti-tension resistance block unit 3;

[0041] Cylindrical rod body 101, rod thread segment 102, inclined surface 103, threaded groove 104;

[0042] Internal thread pipe 201, mounting hole 202, fixing bolt 203;

[0043] Fixed inclined surface block 301, movable inclined surface block 302, threaded segment 303, arc-shaped connecting strip 304, radial fixing groove 305, connecting stud 306. DETAILED DESCRIPTION

[0044] The following description is only the preferred embodiment of the application, and does not limit the scope of the application.

[0045] As shown in the accompanying drawings Figures 1-12 A connecting structure for connecting new and old bridge by using stretchable steel bar to widen the bridge, comprising a steel bar unit 1 for connecting the web of the bridge, an internally threaded pipe unit 2 for screwing and sleeving two adjacent steel bar units 1 at both ends, and a tensile resistance block unit 3 arranged in the internally threaded pipe unit 2 and connecting the steel bar units 1.

[0046] In this embodiment, the complete connecting structure comprises n steel bar units 1, n-1 internally threaded pipe units 2, and n-1 tensile resistance block units 3, wherein n is at least 3. Generally, 3-10 rows and dozens, hundreds or even thousands of columns of the connecting structure are arranged between the new and old bridges, so that the flexible widening structure has sufficient vertical load transmission capacity, sufficient transverse bridge tensile capacity, and appropriate vertical and longitudinal bridge bending deformation capacity, ensuring that:

[0047] First, the new and old bridges, especially the old bridge, are not easy to collapse and shift away from the new bridge;

[0048] Second, the vehicle load on the old bridge can be appropriately distributed to the new bridge;

[0049] Third, when inevitable vertical and longitudinal relative displacement occurs between the new and old bridges, the connecting structure itself and the new and old bridges are not easy to be structurally damaged.

[0050] The main material of the steel bar unit 1, the internally threaded pipe unit 2, and the tensile resistance block unit 3 is high-strength steel, and the shape of the connecting structure is bar-shaped, thereby providing sufficient and appropriate bendable performance, so that the connecting structure achieves a suitable balance between vertical load transmission capacity and vertical and longitudinal bridge relative deformation capacity.

[0051] On the other hand, the transverse bridge distance between the new and old bridges is relatively close, so that the new and old bridges generally do not need to be supported against compression, that is, if the old bridge shifts and collapses towards the new bridge, the new bridge can appropriately support it. Moreover, more importantly, the tensile resistance block unit 3 also has secondary and auxiliary compression resistance.

[0052] Therefore, the old bridge is connected to the new bridge by the tensile resistance block unit 3, and the old bridge is not easy to shift significantly in both directions in the transverse bridge direction.

[0053] Finally, the connecting structure is provided with multiple horizontal and vertical arrangements on the webs of the new and old bridges, thereby realizing greater transverse bridge tensile strength. The rod-shaped feature of the connecting structure has sufficient and appropriate bending capacity, and structural damage is not likely to occur to the connecting structure itself and the new and old bridges, which is unique to the flexible widening method compared to the rigid widening method.

[0054] The steel rod unit 1 includes a cylindrical rod body 101 and a rod upper threaded segment 102 provided at one end position of the cylindrical rod body 101 and used for connecting the internally threaded pipe body unit 2.

[0055] In the present embodiment, the first reason for the appropriate bending deformation of the connecting structure is that the material structure strength and length parameters of the cylindrical rod body 101 are appropriate. Generally, the bending elasticity of the cylindrical rod body 101 is relatively large, and the length is relatively long, so that the connecting structure has a relatively large relative displacement allowance of the new and old bridges and a relatively small vehicle load transmission capacity on the old bridge.

[0056] The steel rod unit 1 further includes an inclined surface 103 provided at the other end position of the cylindrical rod body 101 and used for connecting the bridge web a.

[0057] In the present embodiment, the bridge web a of the T beam is generally vertical, and the bridge web a of the box beam can be vertical or inclined. Therefore, the end of the cylindrical rod body 101 which is not provided with the rod upper threaded segment 102 is provided with the inclined surface 103, which can match the inclined box beam.

[0058] Moreover, it needs to be particularly pointed out that even if the inclined surface 103 needs to be provided on the cylindrical rod body 101, it only needs to be provided on the two most end cylindrical rod bodies 101, and it is still common cylindrical shape with all the cylindrical rod bodies 101.

[0059] Finally, the web connecting plate d is connected with the bolt groove on the web of the new and old bridges through the expansion bolt e, and the inclined surface 103 is welded on the web connecting plate d.

[0060] The internally threaded pipe body unit 2 includes an internally threaded pipe 201 which is screwed and sleeved with two adjacent cylindrical rod bodies 101 at both ends.

[0061] In the present embodiment, the screwing size of the rod upper threaded segment 102 and the internally threaded pipe 201 is adjustable. The role and advantages of this adjustable feature at least include:

[0062] First, even if the same size, the same number of steel rod unit 1, internal thread pipe body unit 2 and tensile resistance block unit 3 combination, can provide different lengths of multiple connection structure, so that in the bridge web a tilt, the gap between the old and new bridge "narrow at the bottom wide" scene, can be effectively connected, without preparing multiple lengths of the steel rod unit 1;

[0063] Second, even if the same size, the same number of steel rod unit 1, internal thread pipe body unit 2 and tensile resistance block unit 3 combination, can independently adjust the timing of each connection structure triggered tensile effect, that is, if the rod on the threaded segment 102 and internal thread pipe 201 screw connection, under the premise of other conditions remain unchanged, the old and new bridge once a small relative displacement, the connection structure can trigger the tensile effect, so that the tensile effect is more sensitive, the relative displacement between the old and new bridge is relatively smaller.

[0064] The tensile resistance block unit 3 comprises a fixed inclined block 301 arranged in the internal thread pipe 201, and a movable inclined block 302 arranged on the end face of the cylindrical rod body 101 and used for clamping the fixed inclined block 301 when the cylindrical rod body 101 is pulled out.

[0065] In the embodiment, the fixed inclined block 301 has a generally right trapezoidal shape, and the movable inclined block 302 has a circular truncated cone shape, and the inclined surfaces of the two are effective triggering positions of the tensile effect, that is, the "thick end" of the fixed inclined block 301 and the "thick end" of the movable inclined block 302 are arranged on the opposite sides, and the cylindrical rod body 101 which is not screwed with the internal thread pipe 201 can trigger the tensile effect when pulling out the internal thread pipe 201.

[0066] On the other hand, the fixed inclined block 301, the movable inclined block 302, the screwed cylindrical rod body 101, and the other cylindrical rod body 101 which is only inserted, have the following two modes to achieve appropriate compression effect:

[0067] First, referring to the attached Figure 2 In the length direction of the cylindrical rod body 101, the size of the movable inclined block 302 is smaller than that of the fixed inclined block 301, the fixed inclined block 301 can block the cylindrical rod body 101 which is only inserted, thereby achieving the compression effect and avoiding the old and new bridges being too close;

[0068] Second, referring to the attached Figure 3 In the length direction of the cylindrical rod body 101, the size of the movable inclined block 302 is larger than that of the fixed inclined block 301, and the screwed cylindrical rod body 101 can block the movable inclined block 302, thereby achieving the compression effect and avoiding the old and new bridges being too close.

[0069] It should be noted that in the bridge widening project, the distance between the new and old bridges is originally small, and the triggering distance of the compression resistance effect reserved at multiple said internal threaded pipe body units 2 of the connecting structure is added together, which may be greater than the distance between the bridges, so that the compression resistance effect of the connecting structure is difficult to directly take effect, and needs to take effect in a specific use scenario, for example, the distance between the new and old bridges in a certain area is relatively large, which can be supported by the above-mentioned compression resistance effect, so as to avoid that the old bridge is too close to the new bridge.

[0070] The tensile resistance block unit 3 further comprises a threaded segment 303 arranged on the fixed inclined surface block 301 and used for screwing the internal threaded pipe 201, and an arc-shaped connecting strip 304 arranged between two adjacent fixed inclined surface blocks 301 in the ring direction.

[0071] In the embodiment, 1 said movable inclined surface block 302 corresponds to 3-10 said fixed inclined surface blocks 301 uniformly distributed in the ring direction, so as to ensure that the movable inclined surface block 302 and the fixed inclined surface blocks 301 are uniformly and sufficiently clamped, and then the tensile resistance effect with sufficient strength is triggered.

[0072] On the other hand, the “fixed” of the fixed inclined surface block 301 means that it is not moved after being rotated and adjusted on the internal threaded pipe 201 and selected to be installed, and its use state is fixed.

[0073] In addition, the function of the arc-shaped connecting strip 304 at least includes:

[0074] Firstly, a plurality of said fixed inclined surface blocks 301 are combined together and fixed to each other, so that a plurality of said threaded segments 303 are arranged in a circle to form an “equivalent” external thread ring which can be screwed with the internal threaded pipe 201 although it is disconnected;

[0075] Secondly, the left and right positions of all said fixed inclined surface blocks 301 on the internal threaded pipe 201 are consistent, that is, all said fixed inclined surface blocks 301 can simultaneously clamp the movable inclined surface block 302, so as to ensure that the tensile resistance effect is more uniform and powerful.

[0076] One end of the rod-shaped threaded segment 102 provided on the cylindrical rod body 101 is arranged on the end face of the fixed inclined surface block 301.

[0077] In the embodiment, the fixed inclined surface block 301 and the arc-shaped connecting strip 304 are integrally formed during production, and the rotation depth of the integral structure in the internal threaded pipe 201 is determined by the length required by the connecting structure. The preset required rotation depth of the rod-shaped threaded segment 102 in the internal threaded pipe 201 is that the rod-shaped threaded segment 102 abuts against the fixed inclined surface block 301.

[0078] The one end of the cylindrical rod body 101 with the rod thread segment 102 is always "set on" or "located on" the smaller and thinner end surface of the fixed inclined block 301 during the entire use process.

[0079] Otherwise, the connection mode of the rod thread segment 102 and the internally threaded pipe 201 is unstable, and any one of them can rotate, thereby changing the screwing size, changing the length of the connection structure, and ultimately affecting the overall performance of the connection structure. Therefore, the common solution is to add a clamping nut f, which is more troublesome. For details, refer to the attached Figure 5 .

[0080] Therefore, conversely, this is the advantage of the structure setting combination use mode that the fixed inclined block 301 is combined first, then screwed with the internally threaded pipe 201, and finally abuts against the cylindrical rod body 101.

[0081] The anti-tension blocking block unit 3 further comprises a radial fixing groove 305 arranged on the fixed inclined block 301; and the internally threaded pipe body unit 2 further comprises a mounting hole 202 arranged on the internally threaded pipe 201, and a fixing bolt 203 arranged on the mounting hole 202 and connected with the radial fixing groove 305.

[0082] In this embodiment, for the fixed inclined block 301, whether the fixing mode through the fixing bolt 203 is combined with the fixing mode through the thread segment 303.

[0083] When the abutting effect of the fixed inclined block 301 against the cylindrical rod body 101 is used together with the bolt fixing effect of the combination of the radial fixing groove 305, the mounting hole 202 and the fixing bolt 203, the mounting hole 202 can be arranged in multiple to ensure that the fixed inclined block 301 can obtain multiple adjustable effective positions of abutting against the cylindrical rod body 101.

[0084] It should be noted that at this time, the arrangement mode of the multiple mounting holes 202 is spiral, because the movement adjustment mode of the radial fixing groove 305 is to rotate and advance at the same time.

[0085] On the other hand, even when the abutting effect of the fixed inclined block 301 against the cylindrical rod body 101 is used together with the bolt fixing effect of the combination of the radial fixing groove 305, the mounting hole 202 and the fixing bolt 203, there can be another use mode, that is, the thread segment 303 is not arranged, and the whole of the fixed inclined block 301 and the arc-shaped connecting strip 304 does not rotate but only slides in the internally threaded pipe 201.

[0086] At this time, the mounting hole 202 can be relatively simply arranged on the inner threaded pipe 201 in one row.

[0087] The anti-pulling block unit 3 further comprises a connecting stud 306 arranged on the movable inclined block 302; and the steel rod unit 1 further comprises a threaded groove 104 arranged on the end face of the cylindrical rod body 101 and used for mounting the connecting stud 306.

[0088] In the embodiment, the rod-on-thread segment 102 is mounted by screwing the inner threaded pipe 201, and the movable inclined block 302 is put into the inner threaded pipe 201 in advance, and then the movable inclined block 302 and the non-screwed end of the cylindrical rod body 101 are connected.

[0089] The smaller end of the movable inclined block 302 is a mounting end, which can be welded and fixed with the cylindrical rod body 101 if it can be exposed to the outside of the inner threaded pipe 201.

[0090] If the movable inclined block 302 is relatively closer to the inner threaded pipe 201, the connecting stud 306 and the threaded groove 104 can be used to connect the movable inclined block 302 and the cylindrical rod body 101. At this time, the operator generally needs to reach into the inner threaded pipe 201 with his hand or a tool to circumferentially fix the movable inclined block 302, so that it can be fully screwed with the cylindrical rod body 101, and then the rod-on-thread segment 102 is screwed and mounted.

[0091] A construction method of a connecting structure for widening old and new bridges by using telescopic steel rods, which comprises the following steps in sequence:

[0092] S1, rotating and mounting the fixed inclined block 301 in the inner threaded pipe 201;

[0093] S2, putting the movable inclined block 302 into the inner threaded pipe 201;

[0094] S3, rotating and mounting the first cylindrical rod body 101 on the inner threaded pipe 201 until the cylindrical rod body 101 clamps the fixed inclined block 301;

[0095] S4, connecting the movable inclined block 302 and the second cylindrical rod body 101.

[0096] In the embodiment, the method is suitable for the anti-pulling block unit 3 with the threaded segment 303 and the arc-shaped connecting strip 304, and the movable inclined block 302 and the second cylindrical rod body 101 are welded.

[0097] When the active slope block 302 and the second cylindrical rod 101 are screwed by the connecting stud 306 and the threaded groove 104, the sequence of S3 and S4 needs to be exchanged.

[0098] The embodiments of the present application are described in detail above with reference to the accompanying drawings, but the present application is not limited to the above-described embodiments, and various modifications can be made within the knowledge of those skilled in the art without departing from the spirit of the present application. These are modifications without creativity, and are protected by the patent law within the scope of the claims of the present application.

Claims

1. A connection structure for widening old and new bridges using expandable steel bars, characterized in that: It includes a steel bar unit (1) for connecting the bridge web (a), an internally threaded tube unit (2) with its two ends screwed and sleeved to two adjacent steel bar units (1), and a tensile blocking block unit (3) disposed in the internally threaded tube unit (2) and connected to the steel bar unit (1). The steel rod unit (1) includes a cylindrical rod body (101) and a threaded section (102) on the rod body (101) at one end for connecting to the internally threaded tube unit (2). The internally threaded tube unit (2) includes an internally threaded tube (201) with its two ends screwed and sleeved to two adjacent cylindrical rods (101). The tensile blocking block unit (3) includes a fixed inclined block (301) disposed in the internal threaded tube (201) and a movable inclined block (302) disposed on the end face of the cylindrical rod (101) and used to engage the fixed inclined block (301) when the cylindrical rod (101) is pulled out. The tensile blocking block unit (3) further includes a threaded segment (303) disposed on the fixed inclined block (301) and used for screwing the internal threaded pipe (201), and an arc-shaped connecting strip (304) disposed between two adjacent fixed inclined blocks (301) in the circumferential direction. The tensile blocking block unit (3) further includes a radial fixing groove (305) provided on the fixed inclined block (301); the internal thread pipe unit (2) further includes a mounting hole (202) provided on the internal thread pipe (201), and a fixing bolt (203) provided on the mounting hole (202) and connected to the radial fixing groove (305).

2. The connection structure for widening old and new bridges using expandable steel bars as described in claim 1, characterized in that: The steel bar unit (1) also includes a chamfered surface (103) located at the other end of the cylindrical bar (101) and used to connect the bridge web (a).

3. The connection structure for widening old and new bridges using expandable steel bars as described in claim 1, characterized in that: The tensile blocking block unit (3) further includes a connecting stud (306) disposed on the movable inclined block (302); the steel rod unit (1) further includes a threaded groove (104) disposed on the end face of the cylindrical rod body (101) and used to install the connecting stud (306).

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