CN118835522A - Connecting structure and construction method for widening new and old bridges by adopting telescopic steel bars - Google Patents

Abstract

The present invention belongs to the technical field of bridge engineering, and in particular, relates to a connection structure and construction method for widening a new and old bridge by using a retractable steel rod. The present invention provides a connection structure for widening a new and old bridge by using a retractable steel rod, and the structure includes: a steel rod unit, an internal threaded pipe unit, and a tensile blocking block unit, so that: 1. the connection structure has sufficient and appropriate tensile strength to avoid excessive distance between the new and old bridges; 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 direction, avoiding the "hard pulling" method to damage its own structure and the new and old bridge structures.

Description

A connection structure and construction method for widening a new and old bridge using retractable steel rods

Technical Field

The invention belongs to the technical field of bridge engineering, and in particular relates to a connection structure and a construction method for widening a new and old bridge by using telescopic steel rods.

Background Art

The main construction contents of the widening project of the new and old bridges include: reinforcing the old bridge, building a new bridge, and connecting the new and old bridges at the cross bridge. The main purpose of this project is to increase the number of lanes to meet traffic needs.

On the other hand, the methods of connecting the old and new bridges can be mainly divided into rigid connection and flexible connection according to the different connection strengths. Rigid connection generally uses steel-concrete structure or large steel frame structure. Its advantage is that the vehicle load on the old bridge can be distributed to the new bridge to the greatest extent, thereby fully protecting the old bridge. However, the rigid connection method is not suitable for scenarios where there will be a small relative displacement between the new and old bridges, otherwise it will not only destroy the connection structure, but also cause greater structural damage to the new and old bridges themselves.

The above-mentioned retractable steel rod method belongs to a flexible connection, and its functional characteristics are: allowing a small relative displacement between the new and old bridges and appropriately transferring vehicle loads. For example, the Chinese utility model patent with the authorization announcement number CN219604175U and the authorization announcement date of 2023.08.29 discloses a wet joint shock-absorbing template for widening old bridges, which belongs to the above-mentioned flexible connection method. The structure of the wet joint shock-absorbing template includes: a shock-absorbing screw, a shock-absorbing spring, a fixing nut, a crossbeam, a casting plate and a fixing screw. The shock-absorbing screw is arranged on the old bridge, and the fixing screw is arranged on the new bridge. A shock-absorbing spring is sleeved on the shock-absorbing screw, and the shock-absorbing screw and the fixing screw are both installed with fixing nuts. The two ends of the crossbeam are respectively fixed with the shock-absorbing screw and the fixing screw, and a casting plate is arranged on the crossbeam.

The wet joint shock-absorbing formwork in this utility model patent has the following advantages: by setting a shock-absorbing structure on one side of the old bridge, it ensures that when the old bridge is open to traffic, the damage to the internal structure of the concrete caused by vibration is reduced, thereby ensuring the pouring quality of the joint concrete.

However, when the wet joint shock-absorbing template is used as a flexible connection structure for widening the new and old bridges, there are at least the following two shortcomings, which are also the technical problems to be solved by the present invention, namely:

First, the effective connection position of the structure is concentrated on the upper part of the new and old bridges, so it is impossible to fully pull the new and old bridges upward in the transverse bridge. When the new and old bridges have a large tendency to move away from each other in the transverse bridge upward, the wet joint shock-absorbing template is easy to be torn;

Second, even as a flexible connection structure, its ability to properly transfer vehicle loads is still too low. 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 shock-absorbing formwork itself is prone to vertical dislocation and fracture, or disconnection from the connection between the old and new bridges.

So to sum up, there is an urgent need for a flexible widening structure for new and old bridges that fully combines the transverse tensile resistance function, the vertical load transfer and sharing function, and the function of allowing relative displacement in the vertical and longitudinal directions of the bridge.

Summary of the invention

The present invention provides a connection structure for widening an old bridge by using a telescopic steel rod, and the structure comprises: a steel rod unit, an internal threaded pipe unit, and a tensile blocking block unit, so that: 1. the connection structure has sufficient and appropriate tensile strength to avoid excessive distance between the new and old bridges; 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 undergo appropriate relative displacement in the vertical and longitudinal directions, thereby avoiding damage to the self-structure and the new and old bridge structures by "hard pulling".

In addition, the present invention also provides a construction method of the above-mentioned connection structure, the steps of which include: rotating and installing a fixed inclined plane block in the internal threaded tube, placing a movable inclined plane block in the internal threaded tube, rotating and installing a first cylindrical rod on the internal threaded tube, until the cylindrical rod clamps the fixed inclined plane block, and connecting the movable inclined plane block and the second cylindrical rod. At this point, a complete tensile structure in the connection structure is installed.

The technical solution adopted by the present invention to solve the above-mentioned problem is: a connection structure for widening the new and old bridges by using retractable steel rods, including a steel rod unit for connecting the bridge web, an internal threaded tube unit whose two ends are respectively screwed and sleeved on two adjacent steel rod units, and a tensile blocking block unit arranged in the internal threaded tube unit and connected to the steel rod unit.

A further preferred technical solution is that the steel rod unit includes a cylindrical rod body and a rod threaded section disposed at one end of the cylindrical rod body and used for connecting to the internally threaded tube unit.

A further preferred technical solution is that the steel rod unit also includes a chamfered surface arranged at the other end of the cylindrical rod body and used for connecting the bridge web.

A further preferred technical solution is that the internally threaded tube unit comprises an internally threaded tube having two ends respectively threadedly connected and sleeved with two adjacent cylindrical rods.

A further preferred technical solution is that the tensile blocking block unit includes a fixed inclined surface block arranged in the internal threaded tube, and a movable inclined surface block arranged on the end surface of the cylindrical rod body and used to engage the fixed inclined surface block when the cylindrical rod body is pulled out.

A further preferred technical solution is that the tensile blocking block unit further includes a threaded segment arranged on the fixed bevel block and used for threaded connection with the internal threaded pipe, and an arc-shaped connecting strip arranged between two adjacent fixed bevel blocks in the annular direction.

A further preferred technical solution is that: the cylindrical rod body is provided with one end of the threaded section on the rod, which is arranged on the end surface of the fixed inclined plane block.

A further preferred technical solution is that: the tensile blocking block unit also includes a radial fixing groove arranged on the fixed ramp block; the internally threaded tube body unit also includes a mounting hole arranged on the internally threaded tube, and a fixing bolt arranged on the mounting hole and connected to the radial fixing groove.

A further preferred technical solution is that: the tensile blocking block unit further includes a connecting stud arranged on the movable inclined plane block; and the steel rod unit further includes a threaded groove arranged on the end surface of the cylindrical rod body and used for installing the connecting stud.

A construction method for widening a connection structure of a new bridge and an old bridge by using a retractable steel rod comprises the following steps in sequence:

S1, rotatably installing the fixed bevel block in the internally threaded tube;

S2, placing the movable ramp block into the internally threaded tube;

S3, rotating and installing the first cylindrical rod on the internally threaded tube until the cylindrical rod clamps the fixed inclined block;

S4, connecting the movable inclined plane block and the second cylindrical rod.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of the position structure of the present invention.

FIG. 2 is a schematic diagram of the first method of realizing the compression resistance effect of the tensile resistance blocking block unit in the present invention.

FIG. 3 is a schematic diagram of a second method for realizing the compression resistance effect of the tensile resistance blocking block unit in the present invention.

FIG. 4 is a schematic structural diagram of the internally threaded pipe unit of the present invention.

FIG. 5 is a schematic diagram showing a fastening method in which an existing clamping nut has to be used if the cylindrical rod body has no clamping and fixing inclined surface block in the present invention.

FIG. 6 is a schematic diagram showing the position and shape of the arc-shaped connecting strip in the present invention.

FIG. 7 is a schematic diagram showing the position and shape of the thread segments and radial fixing grooves in the present invention.

FIG8 is a schematic diagram showing the shape of the first type of steel bar unit in the present invention.

FIG. 9 is a schematic diagram showing the shape of the second type of steel bar unit in the present invention.

FIG. 10 is a schematic diagram showing the shape of the third type of steel bar unit in the present invention.

FIG. 11 is a schematic diagram showing the positions of the connecting studs and the thread grooves in the present invention.

FIG. 12 is a schematic diagram showing the position and shape of the web connecting plate and the expansion bolts in the present invention.

FIG. 13 is a schematic diagram showing the installation position of the connection structure on the new and old bridges in the present invention.

In the figure, the meanings of the symbols are as follows:

Bridge web a, bottom plate b, panel c, web connecting plate d, expansion bolts e, clamping nuts f;

Steel rod unit 1, internal threaded pipe unit 2, tensile stop block unit 3;

A cylindrical rod body 101, a threaded section 102 on the rod, a chamfered surface 103, and a thread groove 104;

Internally threaded tube 201, mounting hole 202, fixing bolt 203;

Fixed bevel block 301 , movable bevel block 302 , threaded segment 303 , arc-shaped connecting strip 304 , radial fixing groove 305 , connecting stud 306 .

DETAILED DESCRIPTION

The following descriptions are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention.

As shown in Figures 1-13, a connection structure for widening an old bridge using retractable steel rods includes a steel rod unit 1 for connecting the bridge web a, internal threaded tube units 2 of two adjacent steel rod units 1 that are respectively screwed and sleeved at both ends, and a tensile blocking block unit 3 that is arranged in the internal threaded tube unit 2 and connected to the steel rod unit 1.

In this embodiment, the complete connection structure includes n steel bar units 1, n-1 internal threaded pipe units 2, and n-1 tensile resistance block units 3, where n is at least 3. Generally, 3-10 rows, as well as dozens, tens or even hundreds of columns of the connection structure are required between the new and old bridges to enable the flexible widening structure to have: sufficient vertical load transfer capacity, sufficient tensile resistance in the transverse direction of the bridge, and appropriate vertical and longitudinal bending deformation capacity, to ensure:

First, the old and new bridges, especially the old bridges, are not likely to collapse and shift to the side away from the new bridge;

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

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 prone to structural damage.

Among them, the main materials of the steel rod unit 1, the internal threaded tube unit 2 and the tensile blocking block unit 3 are all high-strength steel, and the shape of the connection structure is rod-shaped, thereby providing sufficient and appropriate bendability, so that the connection structure can achieve a suitable balance between the vertical load transmission capacity and the vertical and longitudinal bridge upward relative deformation capacity.

On the other hand, the transverse distance between the new and old bridges is relatively close, so there is generally no need for compressive support between the new and old bridges, that is, if the old bridge shifts or collapses to the side of the new bridge, the new bridge can properly support it. More importantly, the tensile block unit 3 also has a secondary, auxiliary compressive performance.

Therefore, the old bridge is connected to the new bridge through the tensile blocking block unit 3, and the old bridge is not easy to be greatly displaced in both directions of the transverse direction of the bridge.

Finally, the connection structure is arranged horizontally and vertically in multiple ways on the webs of the old and new bridges, thereby achieving a greater tensile strength in the transverse direction of the bridge. The rod-like shape of the connection structure gives it sufficient and appropriate bending capacity, and structural damage is not likely to occur to the connection structure itself, as well as the old and new bridges. This is unique to the flexible widening method compared to the rigid widening method.

The steel rod unit 1 includes a cylindrical rod body 101 and a rod threaded section 102 disposed at one end of the cylindrical rod body 101 and used for connecting to the internally threaded tube unit 2 .

In this embodiment, the first reason why the connection structure can bend and deform appropriately is that the material structural strength and length parameters of the cylindrical rod body 101 are suitable. Generally, the bending elasticity of the cylindrical rod body 101 is relatively large and the length is relatively long. Therefore, the connection structure has a relatively large allowable relative displacement between the new and old bridges, and a relatively small vehicle load transmission capacity on the old bridge.

The steel rod unit 1 further includes a chamfered surface 103 disposed at the other end of the cylindrical rod body 101 and used for connecting to the bridge web a.

In this embodiment, the bridge web a of a T-beam is generally vertical, while the bridge web a of a box beam may be vertical or inclined. Therefore, the end of the cylindrical rod body 101 that is not provided with the rod thread section 102 is provided with the chamfered surface 103 to match the box beam with an inclined web.

It should be particularly noted that even if the chamfered surface 103 needs to be provided on the cylindrical rod 101 , it is only required to be provided on the two cylindrical rods 101 at the left and right ends, and they and all the cylindrical rods 101 still have the common cylindrical shape.

Finally, the web connecting plate d is connected to the bolt grooves on the webs of the new and old bridges through expansion bolts e, and the chamfered surface 103 is welded to the web connecting plate d.

The internally threaded tube unit 2 comprises an internally threaded tube 201 with two ends respectively threadedly connected and sleeved with two adjacent cylindrical rods 101 .

In this embodiment, the threaded connection size between the rod threaded section 102 and the internal threaded tube 201 is adjustable. The functions and advantages of this adjustable feature include at least:

First, even if the same size and number of steel bar units 1, internal threaded tube units 2 and tensile block units 3 are used, multiple connection structures of different lengths can be provided, so that in the scenario where the bridge web a is inclined and the gap between the new and old bridges is "narrow at the top and wide at the bottom", it can be effectively connected without preparing the steel bar units 1 of multiple lengths;

Second, even if the same size and number of steel rod units 1, internal threaded tube units 2 and tensile blocking block units 3 are used, the timing for each connection structure to trigger the tensile effect can be independently adjusted, that is, if the threaded section 102 on the rod and the internal threaded tube 201 are largely screwed together, then under the premise that other conditions remain unchanged, once a small relative displacement occurs between the new and old bridges, the connection structure can trigger the tensile effect, making the tensile effect more sensitive and the allowable relative displacement in the transverse direction between the new and old bridges relatively smaller.

The tensile blocking block unit 3 includes a fixed inclined surface block 301 disposed in the internal threaded tube 201 and a movable inclined surface block 302 disposed on the end surface of the cylindrical rod body 101 and used to engage with the fixed inclined surface block 301 when the cylindrical rod body 101 is pulled out.

In this embodiment, the general shape of the fixed inclined plane block 301 is a right-angled trapezoid, and the shape of the movable inclined plane block 302 is a truncated cone. The inclined surfaces of the two are effective triggering positions for the anti-tensile effect, that is, the "thick end" of the fixed inclined plane block 301 and the "thick end" of the movable inclined plane block 302 are arranged on opposite sides. When the cylindrical rod body 101 that is not threadedly connected to the internal threaded tube 201 is pulled out of the internal threaded tube 201, the anti-tensile blocking block unit 3 can trigger the anti-tensile effect.

On the other hand, the fixed inclined plane block 301, the movable inclined plane block 302, the screwed cylindrical rod 101, and the other cylindrical rod 101 that is only inserted can achieve an appropriate compression resistance effect in the following two ways:

First, referring to FIG. 2 , in the length direction of the cylindrical rod 101 , the size of the movable inclined plane block 302 is smaller than the fixed inclined plane block 301 , and the fixed inclined plane block 301 can block the inserted cylindrical rod 101 , thereby achieving a compression resistance effect and preventing the new and old bridges from being too close to each other;

Second, referring to FIG3 , in the length direction of the cylindrical rod 101 , the size of the movable inclined plane block 302 is larger than the fixed inclined plane block 301 , and the screwed cylindrical rod 101 can block the movable inclined plane block 302 , thereby achieving a compression-resistant effect and preventing the new and old bridges from being too close to each other.

It should be noted that in the bridge widening project, the distance between the new and old bridges is relatively small. The sum of the compression resistance triggering distances reserved at the multiple internal threaded pipe units 2 of the connection structure may be greater than the distance between the above-mentioned bridges. As a result, although the compression resistance of the connection structure exists, it is difficult to take effect directly and needs to be effective in specific usage scenarios. For example, if the distance between the new and old bridges in a certain area is relatively large, the above-mentioned compression resistance effect can be used for intermediate support to prevent the old bridge from being too close to the new bridge.

The tensile blocking block unit 3 further includes a threaded segment 303 disposed on the fixed bevel block 301 and used for threading the internal threaded tube 201 , and an arc-shaped connecting strip 304 disposed between two adjacent fixed bevel blocks 301 in the annular direction.

In this embodiment, one of the movable inclined plane blocks 302 corresponds to 3-10 of the fixed inclined plane blocks 301 evenly distributed in the circumferential direction, ensuring that the two are evenly and fully stuck, thereby triggering a tensile effect of sufficient strength.

On the other hand, the word "fixed" of the fixed ramp block 301 means that it will not move after being rotated and adjusted on the internal threaded tube 201 and the installation position is selected, and its use state is fixed.

In addition, the functions of the arc-shaped connecting strip 304 at least include:

First, multiple fixed bevel blocks 301 are combined and fixed to each other, so that multiple thread segments 303 are arranged in a circle to form an "equivalent" external thread ring that is disconnected but can be screwed to the internal thread pipe 201;

Second, the left and right positions of all the fixed bevel blocks 301 on the internal threaded tube 201 are consistent, that is, all the fixed bevel blocks 301 can be engaged with the movable bevel blocks 302 at the same time, ensuring that the tensile effect is more uniform and stronger.

The cylindrical rod body 101 is provided with one end of the rod threaded section 102 , which is arranged on the end surface of the fixed inclined plane block 301 .

In this embodiment, the fixed bevel block 301 and the arc-shaped connecting strip 304 are integrally formed during production, and the screwing depth of the integral structure in the internal threaded tube 201 is determined by the required length of the connecting structure. The preset required screwing depth of the rod thread section 102 in the internal threaded tube 201 is to abut against the fixed bevel block 301.

The end of the cylindrical rod body 101 with the rod threaded section 102 is always "set on" or "located on" the smaller and thinner end face of the fixed bevel block 301 during the entire use process.

Otherwise, the connection between the rod threaded section 102 and the internal threaded tube 201 is unstable, and either one of them can rotate relative to the other, thereby changing the threaded size and the length of the connection structure, and finally affecting the overall performance of the connection structure. Therefore, the common solution is to add a clamping nut f, which is relatively troublesome, and refer to Figure 5 for details.

Therefore, on the contrary, this is the advantage of the structural setting combined with the usage setting that the fixed inclined plane block 301 is first assembled together, then screwed with the internal threaded tube 201, and finally abuts against the cylindrical rod body 101.

The tensile blocking block unit 3 also includes a radial fixing groove 305 arranged on the fixing ramp block 301 ; the internally threaded tube unit 2 also includes a mounting hole 202 arranged on the internally threaded tube 201 , and a fixing bolt 203 arranged on the mounting hole 202 and connected to the radial fixing groove 305 .

In this embodiment, for the fixed ramp block 301, the method of fixing it by the fixing bolt 203 and the method of fixing it by the threaded segment 303 mentioned above can be used in combination.

When the effect of the fixed bevel block 301 against the cylindrical rod body 101 is used together with the bolt fixing effect of the radial fixing groove 305, the mounting hole 202 and the fixing bolt 203, a plurality of mounting holes 202 can be provided to ensure that the fixed bevel block 301 can obtain a plurality of adjustable effective positions against the cylindrical rod body 101.

It should be noted that, at this time, the arrangement of the plurality of mounting holes 202 is spiral, because the movement and adjustment method of the radial fixing slot 305 is to rotate and move forward at the same time.

On the other hand, the effect of the fixed bevel block 301 against the cylindrical rod body 101 can also be used in another way even when used together with the bolt fixing effect of the radial fixing groove 305, the mounting hole 202 and the fixing bolt 203, that is: the threaded segment 303 is not provided, and the fixed bevel block 301 and the arc-shaped connecting strip 304 as a whole do not rotate but only slide in the internal threaded tube 201.

At this time, the mounting holes 202 can be relatively simply arranged in a row on the internally threaded tube 201 .

The tensile blocking block unit 3 further includes a connecting stud 306 disposed on the movable inclined plane block 302 ; the steel rod unit 1 further includes a threaded groove 104 disposed on the end surface of the cylindrical rod body 101 and used for installing the connecting stud 306 .

In this embodiment, before the threaded section 102 on the rod is installed and screwed to the internal threaded tube 201, the movable inclined plane block 302 needs to be placed in advance into the internal threaded tube 201, and finally the movable inclined plane block 302 and the non-threaded end on the other cylindrical rod body 101 are connected.

The smaller end of the movable inclined plane block 302 is a mounting end. If the mounting end can be exposed to the outside of the internal threaded tube 201 , it can be fixed to the cylindrical rod body 101 by welding.

If the movable bevel block 302 is relatively close to the inside of the internal threaded tube 201, the movable bevel block 302 and the cylindrical rod 101 can be connected through the connecting stud 306 and the thread groove 104. At this time, the operator generally needs to reach into the internal threaded tube 201 with his hand or a tool, and then fix the movable bevel block 302 in an annular direction, so that it can be fully screwed to the cylindrical rod 101, and then screw the threaded section 102 on the rod.

A construction method for widening a connection structure of a new bridge and an old bridge by using a retractable steel rod comprises the following steps in sequence:

S1, rotatably installing the fixed bevel block 301 in the internal threaded tube 201;

S2, placing the movable inclined plane block 302 into the internal threaded tube 201;

S3, rotating and installing the first cylindrical rod 101 on the internal threaded tube 201 until the cylindrical rod 101 clamps the fixed inclined plane block 301;

S4, connecting the movable inclined plane block 302 and the second cylindrical rod body 101.

In this embodiment, the method is applicable to the tensile blocking block unit 3 with the threaded segment 303 and the arc-shaped connecting strip 304 , and the movable inclined plane block 302 and the second cylindrical rod body 101 are welded.

When the movable inclined plane block 302 and the second cylindrical rod body 101 are screwed together through the connecting stud 306 and the thread groove 104, the order of S3 and S4 needs to be exchanged.

The embodiments of the present invention are described in detail above in conjunction with the accompanying drawings, but the present invention is not limited to the above embodiments. Various modifications can be made within the knowledge of ordinary technicians in the technical field without departing from the purpose of the present invention. These are all non-creative modifications and are protected by patent law as long as they are within the scope of the claims of the present invention.

Claims (10)

1. A connection structure for widening an old bridge by using a telescopic steel rod, characterized in that it comprises a steel rod unit (1) for connecting the bridge web (a), internally threaded tube units (2) at both ends of which are respectively screwed and sleeved to two adjacent steel rod units (1), and a tensile blocking block unit (3) arranged in the internally threaded tube unit (2) and connected to the steel rod unit (1). 2. A connection structure for widening an old bridge by using a retractable steel rod according to claim 1, characterized in that: the steel rod unit (1) comprises a cylindrical rod body (101), and a rod threaded section (102) arranged at one end of the cylindrical rod body (101) and used to connect the internally threaded tube unit (2). 3. A connection structure for widening an old bridge by using a retractable steel rod according to claim 2, characterized in that: the steel rod unit (1) also includes a chamfered surface (103) arranged at the other end of the cylindrical rod body (101) and used to connect the bridge web (a). 4. A connection structure for widening an old bridge by using a telescopic steel rod according to claim 2, characterized in that: the internally threaded tube unit (2) comprises an internally threaded tube (201) with two ends respectively screwed and sleeved to two adjacent cylindrical rods (101). 5. A connection structure for widening an old bridge by using a retractable steel rod according to claim 4, characterized in that the tensile blocking block unit (3) comprises a fixed inclined surface block (301) arranged in the internal threaded tube (201), and a movable inclined surface block (302) arranged on the end surface of the cylindrical rod body (101) and used to engage the fixed inclined surface block (301) when the cylindrical rod body (101) is pulled out. 6. A connection structure for widening an old bridge by using a retractable steel rod according to claim 5, characterized in that: the tensile blocking block unit (3) also includes a threaded segment (303) arranged on the fixed inclined surface block (301) and used for screwing the internal threaded tube (201), and an arc-shaped connecting strip (304) arranged between two adjacent fixed inclined surface blocks (301) in the annular direction. 7. A connection structure for widening an old bridge by using a telescopic steel rod according to claim 6, characterized in that: one end of the rod threaded section (102) is provided on the cylindrical rod body (101) and is arranged on the end surface of the fixed inclined plane block (301). 8. According to claim 5, a connection structure for widening a new bridge with a retractable steel rod is characterized in that: the tensile blocking block unit (3) also includes a radial fixing groove (305) arranged on the fixed inclined block (301); the internal threaded tube unit (2) also includes a mounting hole (202) arranged on the internal threaded tube (201), and a fixing bolt (203) arranged on the mounting hole (202) and connected to the radial fixing groove (305). 9. A connection structure for widening an old bridge by using a retractable steel rod according to claim 5, characterized in that: the tensile blocking block unit (3) further comprises a connecting stud (306) arranged on the movable inclined plane block (302); the steel rod unit (1) further comprises a threaded groove (104) arranged on the end surface of the cylindrical rod body (101) and used for installing the connecting stud (306). 10. A construction method for widening a connection structure of a new bridge and an old bridge using a telescopic steel rod as claimed in claim 7, characterized in that it comprises the following steps in sequence: S1, rotatably installing the fixed bevel block (301) in the internally threaded tube (201); S2, placing the movable inclined plane block (302) into the internally threaded tube (201); S3, rotating and installing the first cylindrical rod (101) on the internally threaded tube (201) until the cylindrical rod (101) clamps the fixed inclined surface block (301); S4, connecting the movable inclined plane block (302) and the second cylindrical rod (101).