River-oriented deep foundation pit steel cofferdam and steel trestle combined system and construction method thereof

Abstract

The invention discloses a riverside deep foundation pit steel cofferdam and steel trestle combination system and a construction method thereof, and belongs to the technical field of foundation pit construction. Comprising a steel cofferdam arranged on the side, near the river, of a foundation pit, a steel trestle is arranged on the outer side of the steel cofferdam, a plurality of connecting rod assemblies are vertically arranged between the steel cofferdam and the steel trestle, the two ends of each connecting rod assembly are connected to the steel cofferdam and the steel trestle correspondingly, and the connecting rod assemblies serve as outer supporting assemblies of the steel cofferdam. The steel cofferdam is supported through the acting force provided by the steel trestle; the steel cofferdam comprises a plurality of steel pipe piles arranged side by side, the steel trestle comprises a pier composed of a plurality of vertically-spliced steel frame sections, and each steel frame section comprises a plurality of vertical steel pipes distributed in a rectangular mode and transverse steel pipes connecting the vertical steel pipes into a whole. According to the technical scheme, the steel cofferdam supporting structure is simplified, and the foundation pit construction efficiency is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of foundation pit construction, and particularly relates to a combined system of a steel cofferdam and a steel trestle for a deep foundation pit by the river and a construction method thereof. Background Technique

[0002] The steel cofferdam and the steel trestle are respectively indispensable temporary structures for the construction of deep foundation pits by the river. The steel cofferdam mainly provides safety guarantee for the excavation of water-crossing foundation pits and the construction of main structures, and the steel trestle mainly provides a transportation channel for the soil body and materials during the excavation of the foundation pit and the construction of the main structure.

[0003] The internal support steel cofferdam is one of the commonly used structural forms in foundation pit construction. However, there are problems such as complex operation and high safety risks in the internal support diversion modification, and the internal support occupies the internal space of the foundation pit, which is likely to affect mechanical operation and vehicle passage. Therefore, when the steel trestle and the steel cofferdam are simultaneously applied to the construction of deep foundation pits by the river, how to optimize the layout of the steel trestle and the steel cofferdam structures, reduce or eliminate the internal support in the foundation pit, and achieve the purpose of cost saving and construction efficiency improvement is an urgent problem to be solved. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide a combined system of a steel cofferdam and a steel trestle for a deep foundation pit by the river and a construction method thereof, so as to solve the problem that the support of the steel cofferdam by the existing internal support method during the construction of the foundation pit by the river causes inconvenience to the foundation pit construction.

[0005] To achieve the above purpose, the present invention provides the following technical solutions: A combined system of a steel cofferdam and a steel trestle for a deep foundation pit by the river according to the present invention includes a steel cofferdam arranged on one side of the foundation pit facing the river. A steel trestle is arranged outside the steel cofferdam. A plurality of groups of connecting rod assemblies are vertically arranged between the steel cofferdam and the steel trestle. The two ends of each connecting rod assembly are respectively connected to the steel cofferdam and the steel trestle. The plurality of groups of connecting rod assemblies are used as external support assemblies for the steel cofferdam and form support for the steel cofferdam through the acting force provided by the steel trestle. The steel cofferdam includes a plurality of steel pipe piles arranged side by side. The steel trestle includes a pier composed of a plurality of vertically spliced steel frame segments. Each steel frame segment includes a plurality of vertically arranged steel pipes distributed in a rectangular shape and a horizontal steel pipe connecting the plurality of vertically arranged steel pipes into one body. The connecting rod assembly includes a plurality of first connecting blocks, a plurality of second connecting blocks, a plurality of telescopic rods and a plurality of limit pins. The plurality of first connecting blocks are respectively fixed on one side surface of the plurality of steel pipe piles facing the vertically arranged steel pipes. The plurality of second connecting blocks are respectively fixed on one side surface of the plurality of vertically arranged steel pipes facing the steel pipe piles. The two ends of the plurality of telescopic rods are respectively connected to the first connecting blocks and the second connecting blocks through the plurality of limit pins.

[0006] Furthermore, the telescopic rod includes a mounting tube, on which an upper support rod and a lower support rod are arranged in parallel. The upper support rod and the lower support rod are both slidably arranged on the mounting tube. A number of evenly distributed grooves are provided on both the upper support rod and the lower support rod. An insertion plate is arranged inside the mounting tube. Two limiting holes are vertically arranged on the insertion plate. The thickness of the insertion plate matches the width of the groove. The upper support rod and the lower support rod are respectively located in the two limiting holes. An end plate is provided at the upper end of the mounting tube, and a bottom plate is provided at the lower end of the mounting tube. A connecting shaft is arranged in the middle of the end plate. One end of the connecting shaft is fixed to the end of the insertion plate, and a baffle is arranged at the other end of the connecting shaft. A spring is arranged between the baffle and the end. The two ends of the spring are respectively fixed to the baffle and the end plate. The spring is used to tightly press the upper end of the limiting hole against the groove.

[0007] Furthermore, a fixing plate is provided below the lower support rod. The fixing plate is fixedly connected to the vertical steel pipe. Two blocking rods are symmetrically arranged on the fixing plate. One end of the blocking rod is connected to the fixing plate. A number of deflection limiting components are also arranged on the fixing plate. The deflection limiting components are arranged between adjacent upper support rods. The deflection limiting component includes symmetrically arranged arc-shaped taper plates. The small-diameter end of the arc-shaped taper plate is rotatably connected to the fixing plate. A fixing tube is arranged between the two arc-shaped taper plates. The fixing tube is fixedly connected to the fixing plate. An adjusting screw is arranged inside the fixing tube. The adjusting screw is threadedly connected to the fixing tube. An extrusion sphere is arranged between the two arc-shaped taper plates. A traction rope is arranged between the extrusion sphere and the adjusting screw. The two ends of the traction rope are respectively connected to the extrusion sphere and the adjusting screw.

[0008] Furthermore, a fixing seat is arranged on the fixing plate, and a rotating shaft is arranged on the fixing seat. The small-diameter end of the arc-shaped taper plate is fixedly connected to the rotating shaft.

[0009] A construction method for a combined system of a steel cofferdam and a steel trestle in a deep foundation pit near a river includes the following construction steps: First, determine the construction position of the foundation pit, and lay steel pipe piles on one side of the foundation pit close to the river until a steel cofferdam for water blocking is formed. Second, determine the construction position of the steel trestle outside the steel cofferdam. After splicing a number of steel frame segments, they are erected at the designated position to form the piers of the steel trestle. The steel frame segments include vertical steel pipes and horizontal steel pipes. Then, adjust the length of the telescopic rod, and use limit pins to connect the two ends of the telescopic rod to the steel pipe pile and the vertical steel pipe respectively until the connection of all steel pipe piles and vertical steel pipes is completed. Among them, the telescopic rods located above the same fixing plate are all located between the two blocking rods arranged on the fixing plate, and a number of deflection limiting components are all located between two adjacent telescopic rods. Then, rotate the adjusting screw rod to pull down the towing rope with the adjusting screw rod. The towing rope drives the extrusion sphere to move towards the small-diameter end of the arc taper plate. Under the action of the extrusion sphere, the arc taper plate is driven to rotate towards both sides and contact the telescopic rods on both sides, thereby restricting the deflection of the telescopic rods. Finally, lay the bridge deck on the bridge end to form a complete combined system of the steel cofferdam and the steel trestle.

[0010] The beneficial effects of the present invention are as follows: In this technical solution, a number of steel pipe piles are connected to the steel frame section of the steel trestle through the connecting rod assembly, so as to form a stress system between the steel cofferdam and the steel trestle. That is, after the steel trestle is erected, since the bridge pier is fixed, under the action of the telescopic rod, a force will be provided to a number of steel pipe piles, thereby restricting the position of the steel pipe piles. Therefore, it is equivalent to forming an external support structure for the steel cofferdam, that is, while ensuring the normal operation of the steel cofferdam, it can also avoid the problem in the prior art that the internal support system is arranged inside the steel cofferdam, resulting in interference with the internal construction of the foundation pit.

[0011] Other advantages, objectives and features of the present invention will be described in the subsequent description, and to some extent, they are obvious to those skilled in the art, or those skilled in the art can obtain teachings from the practice of the present invention. The objectives and other advantages of the present invention can be achieved and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] In order to make the objectives, technical solutions and beneficial effects of the present invention clearer, the present invention provides the following drawings for illustration: Figure 1 It is a top view of the foundation pit-steel cofferdam-steel trestle combined system in the present invention; Figure 2 It is a three-dimensional schematic diagram of the connection between the steel cofferdam and the steel trestle in the present invention; Figure 3 It is a schematic top view of the steel cofferdam-steel trestle combined system in the present invention; Figure 4 It is a three-dimensional schematic diagram of the telescopic rod structure in the present invention; Figure 5 It is a schematic cross-sectional view of the telescopic rod structure in the present invention; Figure 6 It is a three-dimensional schematic diagram of the deflection limiting component in the present invention; Figure 7 It is a schematic cross-sectional view of the deflection limiting component in the present invention; Figure 8 It is a schematic diagram of an elastic mesh pocket arranged inside the arc taper plate in the present invention.

[0013] The reference signs in the drawings are as follows: 1. Foundation pit; 2. Steel pipe pile; 3. Steel frame segment; 31. Vertical steel pipe; 32. Horizontal steel pipe; 4. Bridge deck; 5. Connecting rod assembly; 51. First connecting block; 52. Second connecting block; 53. Expansion rod; 530. Upper support rod; 531. Lower support rod; 532. Groove; 533. Bottom plate; 534. Installation pipe; 535. End plate; 536. Spring; 537. Insertion plate; 538. Limit hole; 539. Connecting shaft; 54. Limit pin; 6. Fixed plate; 7. Deflection limit assembly; 71. Stop bar; 72. Arc taper plate; 73. Fixed seat; 74. Rotating shaft; 75. Extrusion sphere; 76. Adjusting screw; 77. Fixed pipe; 78. Towing rope; 79. Elastic net pocket. Detailed implementation mode

[0014] As Figures 1 to 7 shown, a combined system of a steel cofferdam and a steel trestle for a deep foundation pit near a river of the present invention includes a steel cofferdam arranged on the riverside side of the foundation pit 1. There is a steel trestle on the outer side of the steel cofferdam. A number of groups of connecting rod assemblies 5 are vertically arranged between the steel cofferdam and the steel trestle. The two ends of the connecting rod assembly 5 are respectively connected to the steel cofferdam and the steel trestle. The number of groups of connecting rod assemblies 5 serves as an external support assembly for the steel cofferdam and forms a support for the steel cofferdam through the acting force provided by the steel trestle; The steel cofferdam includes a number of steel pipe piles 2 arranged side by side. The steel pipe pile 2 is a lock-type steel pipe pile 2 in the prior art. The steel trestle includes a pier composed of a number of vertically spliced steel frame segments 3. The steel frame segment 3 includes a number of vertically arranged steel pipes 31 distributed in a rectangle and horizontal steel pipes 32 connecting the number of vertically arranged steel pipes 31 into one body. The connecting rod assembly 5 includes a number of first connecting blocks 51, a number of second connecting blocks 52, a number of expansion rods 53 and a number of limit pins 54. The number of first connecting blocks 51 are respectively fixed on the side surfaces of the number of steel pipe piles 2 facing the vertical steel pipes 31 by welding. The number of second connecting blocks 52 are respectively fixed on the side surfaces of the number of vertical steel pipes 31 facing the steel pipe piles 2 by welding. The two ends of the number of expansion rods 53 are respectively connected to the first connecting blocks 51 and the second connecting blocks 52 by a number of limit pins 54. Of course, it is not difficult to understand that diagonal braces and other means can be arranged on the pier to increase the bearing capacity of the pier and ensure the support effect on the steel cofferdam.

[0015] The technical effects obtained by the above technical solutions are as follows: A number of steel pipe piles 2 are connected to the steel frame segment 3 of the steel trestle through the connecting rod assembly 5, so as to form a force system between the steel cofferdam and the steel trestle. That is, after the steel trestle is erected, since the pier is fixed, under the action of the telescopic rod 53, a force will be provided to a number of steel pipe piles 2, thereby limiting the position of the steel pipe piles 2. Therefore, it is equivalent to forming an external support structure for the steel cofferdam, that is, while ensuring the normal operation of the steel cofferdam, it can also avoid the problem that in the prior art, an internal support system is arranged inside the steel cofferdam, resulting in interference with the internal construction of the foundation pit 1.

[0016] In an implementable manner, the telescopic rod 53 includes a mounting pipe 534. An upper support rod 530 and a lower support rod 531 are arranged in parallel on the mounting pipe 534. Both the upper support rod 530 and the lower support rod 531 are slidably arranged on the mounting pipe 534. A number of uniformly distributed grooves 532 are provided on both the upper support rod 530 and the lower support rod 531. An insertion plate 537 is arranged inside the mounting pipe 534. Two limiting holes 538 are arranged vertically on the insertion plate 537. The thickness of the insertion plate 537 matches the width of the groove 532. The upper support rod 530 and the lower support rod 531 are respectively located in the two limiting holes 538. An end plate 535 is arranged at the upper end of the mounting pipe 534. A bottom plate 533 is arranged at the lower end of the mounting pipe 534. A connecting shaft 539 is arranged in the middle of the end plate 535. One end of the connecting shaft 539 is fixed to the end of the insertion plate 537. A baffle is arranged at the other end of the connecting shaft 539. A spring 536 is arranged between the baffle and the end. Both ends of the spring 536 are respectively fixed to the baffle and the end plate 535. The spring 536 is used to press the upper end of the limiting hole 538 tightly into the groove 532.

[0017] The working principle of the above technical solution is as follows: Since during actual construction, the distance between the steel pipe pile 2 and the vertical steel pipe 31 is uncertain, and the distance between the two is determined according to the actual construction conditions, it is necessary to use the telescopic rod 53 to meet the construction requirements for different distances. Specifically, when the length of the telescopic rod 53 needs to be adjusted, only need to pull up the connecting shaft 539 to move the insertion plate 537 upward, so that the limiting holes 538 on the insertion plate 537 are separated from the grooves 532. At this time, the lengths of the upper support rod 530 and the lower support rod 531 relative to the mounting pipe 534 can be adjusted, thereby adjusting the overall length. After the length adjustment is completed, only need to release the connecting shaft 539. Under the action of the spring 536, the upper end of the limiting hole 538 is pressed down into the groove 532, so as to limit the rotation and movement of the upper telescopic rod 53 and the lower telescopic rod, and then lock the adjusted length.

[0018] The working effects of the above technical solution are as follows: With this setting method of the telescopic rod 53, the methods of length adjustment and length locking are simple and fast, which can greatly improve the construction effect. At the same time, compared with the adjustment method of screw telescoping in the prior art, this method is more suitable for harsh construction environments. Because if the screw telescoping method is adopted, the threads are easily adhered by impurities such as dust at the construction site, resulting in the problem that the threads cannot rotate during use.

[0019] In an implementable manner, a fixed plate 6 is provided below the lower support rod 531. The fixed plate 6 is fixedly connected to the vertical steel pipe 31. The fixed plate 6 is symmetrically provided with stop rods 71. One end of the stop rod 71 is connected to the fixed plate 6. The fixed plate 6 is also provided with a plurality of deflection limiting components 7. The deflection limiting components 7 are arranged between adjacent upper support rods 530. The deflection limiting component 7 includes symmetrically arranged arc taper plates 72. The small diameter end of the arc taper plate 72 is rotatably connected to the fixed plate 6. A fixed pipe 77 is provided between the two arc taper plates 72. The fixed pipe 77 is fixedly connected to the fixed plate 6. An adjusting screw rod 76 is arranged inside the fixed pipe 77. The adjusting screw rod 76 is threadedly connected to the fixed pipe 77. An extrusion sphere 75 is provided between the two arc taper plates 72. A traction rope 78 is provided between the extrusion sphere 75 and the adjusting screw rod 76. The two ends of the traction rope 78 are respectively connected to the extrusion sphere 75 and the adjusting screw rod 76.

[0020] The working principle of the above technical solution is as follows: In order to achieve the rapid installation of the telescopic rod 53, the connection method of the limit pin 54 is adopted. However, there are deficiencies in this connection method during actual use, that is, when the steel cofferdam is subjected to a lateral force, the telescopic rod 53 will deflect with the lateral movement of the steel cofferdam, that is, this connection method cannot limit the lateral movement of the steel cofferdam.

[0021] By setting the deflection limiting component 7, the deflection of the telescopic rod 53 can be restricted, and further the lateral movement of the steel cofferdam can be restricted, further improving the use effect of the steel cofferdam. The specific working principle is as follows: After the telescopic rod 53 is installed, at this time, by rotating the adjusting screw rod 76, the adjusting screw rod 76 drives the traction rope 78 to move downward, and then drives the extrusion sphere 75 to move downward, and then the extrusion sphere 75 moves towards the small diameter end of the arc taper plate 72. That is, under the extrusion action, the symmetrically arranged arc taper plates 72 will deflect outward, and then contact the upper support rods 530 in the two telescopic rods 53 on both sides, and then limit the deflection of a plurality of telescopic rods 53 arranged in the middle. The telescopic rod 53 at the edge of the fixed plate 6 is limited by the stop rod 71. Then all the telescopic rods 53 above the fixed plate 6 are limited by deflection, and then form a stress integral body. That is, when the steel cofferdam is subjected to a lateral force, all the telescopic rods 53 participate in restricting the lateral movement of the steel cofferdam, improving the stress effect, and avoiding the problem that individual telescopic rods 53 participate in resisting the displacement of the steel cofferdam, resulting in bending or breaking.

[0022] It should be noted that in this technical solution, the arc taper plate 72 can be understood as a component formed after a hollow frustum is cut open. The advantage of this setting method is that it can limit the extrusion sphere 75 to prevent it from separating from between the two symmetrically arranged arc taper plates 72. At the same time, the advantage of using the extrusion sphere 75 is that during actual construction, there may be certain errors, that is, it can be understood that the deflection limiting component 7 is not located exactly in the middle between the two arc taper plates 72. That is, at this time, when performing limiting, one arc taper plate 72 needs to deflect at a small angle and the other needs to deflect at a large angle. Therefore, the characteristics that the surface of the extrusion sphere 75 can be in contact with the two arc taper plates 72 respectively and the extrusion sphere 75 can move horizontally between the two arc taper plates 72 are cleverly utilized, so that the extrusion sphere 75 can extrude the two arc taper plates 72 to deflect at different angles, and at the same time can support and transfer force with the inner walls of the two arc taper plates 72, thereby improving the deflection limiting effect and the use effect.

[0023] As Figure 8 shown, in an implementable manner, an elastic mesh bag 79 is provided between the two arc taper plates 72. The two ends of the elastic mesh bag 79 are respectively fixed on the inner side surfaces of the two arc taper plates 72. The extrusion sphere 75 is placed on the elastic mesh bag 79, and the traction rope 78 is arranged through the elastic mesh bag 79.

[0024] The working principle of the above technical solution is as follows: Under normal conditions, under the action of the gravity of the extrusion sphere 75, the elastic mesh bag 79 will be deformed downward by force, and then pull the two arc taper plates 72 towards the middle, making them closely adhere to the inner wall of the extrusion sphere 75, preventing the extrusion sphere 75 from falling to the lower part of the arc taper plates 72 under the action of gravity, resulting in too large an opening angle of the two arc taper plates 72 and blocking the installation space of the telescopic rod 53, causing problems in inconvenient installation. At the same time, in this setting method, due to the action of the elastic mesh bag 79, the extrusion sphere 75 is located above the arc taper plates 72, and the two arc taper plates 72 and the extrusion sphere 75 are closely arranged, that is, at this time, the three are closely arranged, and the occupied area of the three is small and the blocked area is small, which is convenient for the construction of the telescopic rod 53 and convenient for the construction personnel to move the whole of the three. It is not difficult to understand that when the traction rope 78 acts, the force exerted on the arc taper plate 72 when the extrusion sphere 75 moves downward is greater than the pulling force of the elastic mesh bag 79 acting on the arc taper plate 72. Therefore, the setting of the elastic mesh bag 79 does not affect the force and deflection of the arc taper plate 72.

[0025] In an implementable manner, a fixed seat 73 is provided on the fixing plate 6, a rotating shaft 74 is provided on the fixed seat 73, and the small diameter end of the arc taper plate 72 is fixedly connected to the rotating shaft 74. This way of rotational connection is simple and reliable, which is convenient for construction.

[0026] A construction method for a combined system of a steel cofferdam and a steel trestle in a deep foundation pit near a river, comprising the following construction steps: First, determine the construction position of the foundation pit 1, and lay steel pipe piles 2 on one side of the foundation pit 1 close to the river until a steel cofferdam for water blocking is formed; Secondly, determine the construction position of the steel trestle outside the steel cofferdam, splice several steel frame segments 3 and erect them at the designated position to form the piers of the steel trestle, wherein the steel frame segment 3 includes a vertical steel pipe 31 and a horizontal steel pipe 32; Then, adjust the length of the telescopic rod 53, and use the limit pin 54 to connect the two ends of the telescopic rod 53 to the steel pipe pile 2 and the vertical steel pipe 31 respectively until the connection of all the steel pipe piles 2 and the vertical steel pipes 31 is completed. Among them, the telescopic rods 53 located above the same fixed plate 6 are all located between the two retaining rods 71 arranged on the fixed plate, and several deflection limiting components 7 are all located between two adjacent telescopic rods 53; Then, rotate the adjusting screw 76 to make the adjusting screw 76 pull down the towing rope 78, and the towing rope 78 drives the extrusion sphere 75 to move towards the small diameter end of the arc taper plate 72. Under the action of the extrusion sphere 75, the arc taper plate 72 is driven to rotate towards both sides and contact with the telescopic rods 53 on both sides, thereby restricting the deflection of the telescopic rods 53; Finally, lay the bridge deck 4 on the bridge end to form a complete combined system of the steel cofferdam and the steel trestle.

[0027] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention rather than to limit them. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made in form and details without departing from the scope defined by the claims of the present invention.

Claims

1. A combined system of a steel cofferdam and a steel trestle for a deep foundation pit near a river, characterized in that: It includes a steel cofferdam arranged on the riverside side of the foundation pit (1). A steel trestle is provided on the outer side of the steel cofferdam. A number of groups of connecting rod assemblies (5) are vertically arranged between the steel cofferdam and the steel trestle. The two ends of the connecting rod assembly (5) are respectively connected to the steel cofferdam and the steel trestle. The number of groups of the connecting rod assemblies (5) serve as the external support assemblies of the steel cofferdam and form support for the steel cofferdam through the acting force provided by the steel trestle. The steel cofferdam includes a number of steel pipe piles (2) arranged side by side. The steel trestle includes a pier composed of a number of vertically spliced steel frame segments (3). The steel frame segment (3) includes a number of vertically arranged steel pipes (31) distributed in a rectangular shape and a transverse steel pipe (32) connecting the number of vertically arranged steel pipes (31) into one body. The connecting rod assembly (5) includes a number of first connecting blocks (51), a number of second connecting blocks (52), a number of telescopic rods (53) and a number of limit pins (54). The number of the first connecting blocks (51) are respectively fixed on the side surfaces of the number of steel pipe piles (2) facing the vertically arranged steel pipes (31). The number of the second connecting blocks (52) are respectively fixed on the side surfaces of the number of the vertically arranged steel pipes (31) facing the steel pipe piles (2). The two ends of the number of telescopic rods (53) are respectively connected to the first connecting block (51) and the second connecting block (52) through a number of limit pins (54).

2. The combined system of a steel cofferdam and a steel trestle for a deep foundation pit near a river according to claim 1, characterized in that: The telescopic rod (53) includes a mounting pipe (534). An upper support rod (530) and a lower support rod (531) are arranged in parallel on the mounting pipe (534). The upper support rod (530) and the lower support rod (531) are both slidably arranged on the mounting pipe (534). A number of uniformly distributed grooves (532) are provided on both the upper support rod (530) and the lower support rod (531). An insertion plate (537) is arranged inside the mounting pipe (534). Two limit holes (538) are vertically arranged on the insertion plate (537). The thickness of the insertion plate (537) matches the width of the groove (532). The upper support rod (530) and the lower support rod (531) are respectively located in the two limit holes (538). An end plate (535) is arranged at the upper end of the mounting pipe (534). A bottom plate (533) is arranged at the lower end of the mounting pipe (534). A connecting shaft (539) is arranged in the middle of the end plate (535). One end of the connecting shaft (539) is fixed to the end of the insertion plate (537). A baffle is arranged at the other end of the connecting shaft (539). A spring (536) is arranged between the baffle and the end. The two ends of the spring (536) are respectively fixed to the baffle and the end plate (535). The spring (536) is used to tightly press the upper end of the limit hole (538) against the groove (532).

3. The combined system of a steel cofferdam and a steel trestle for a deep foundation pit near a river as claimed in claim 2, wherein: Below the lower support rod (531), there is a fixing plate (6) which is fixedly connected to the vertical steel pipe (31). On the fixing plate (6), there are symmetrically arranged stop rods (71). One end of the stop rod (71) is connected to the fixing plate (6). The fixing plate (6) is also provided with a number of deflection limiting components (7) which are arranged between adjacent upper support rods (530). The deflection limiting component (7) includes symmetrically arranged arc-shaped taper plates (72). The small-diameter end of the arc-shaped taper plate (72) is rotatably connected to the fixing plate (6). Between the two arc-shaped taper plates (72), there is a fixed pipe (77) which is fixedly connected to the fixing plate (6). Inside the fixed pipe (77), there is an adjusting screw rod (76) which is threadedly connected to the fixed pipe (77). Between the two arc-shaped taper plates (72), there is an extrusion sphere (75). Between the extrusion sphere (75) and the adjusting screw rod (76), there is a traction rope (78). The two ends of the traction rope (78) are respectively connected to the extrusion sphere (75) and the adjusting screw rod (76).

4. A combined system of a steel cofferdam and a steel trestle for a deep foundation pit near a river, characterized in that: On the fixing plate (6), there is a fixed seat (73). On the fixed seat (73), there is a rotating shaft (74). The small-diameter end of the arc-shaped taper plate (72) is fixedly connected to the rotating shaft (74).

5. The combined system of a steel cofferdam and a steel trestle for a deep foundation pit near a river according to claim 3, characterized in that: Between the two arc-shaped taper plates (72), there is an elastic net bag (79). The two ends of the elastic net bag (79) are respectively fixed to the inner sides of the two arc-shaped taper plates (72). The extrusion sphere (75) is placed on the elastic net bag (79). The traction rope (78) passes through the elastic net bag (79).

6. The construction method of a combined system of a steel cofferdam and a steel trestle for a deep foundation pit near a river, according to any one of claims 1-5, is characterized in that: It includes the following construction steps: First, determine the construction position of the foundation pit (1), and lay steel pipe piles (2) on one side of the foundation pit (1) close to the river until a steel cofferdam for water blocking is formed; Second, determine the construction position of the steel trestle outside the steel cofferdam. After splicing a number of steel frame segments (3), erect them at the designated position to form the piers of the steel trestle. The steel frame segment (3) includes a vertical steel pipe (31) and a horizontal steel pipe (32); Then, adjust the length of the telescopic rod (53), and use the limit pin (54) to connect the two ends of the telescopic rod (53) to the steel pipe pile (2) and the vertical steel pipe (31) respectively until the connection of all the steel pipe piles (2) and the vertical steel pipes (31) is completed. Among them, the telescopic rods (53) above the same fixing plate (6) are all located between the two stop rods (71) arranged on the fixing plate, and a number of deflection limiting components (7) are all located between two adjacent telescopic rods (53); Then, rotate the adjusting screw rod (76) to make the adjusting screw rod (76) pull down the traction rope (78). The traction rope (78) drives the extrusion sphere (75) to move towards the small-diameter end of the arc-shaped taper plate (72). Under the action of the extrusion sphere (75), the arc-shaped taper plate (72) is driven to rotate towards both sides and contact the telescopic rods (53) on both sides, thereby restricting the deflection of the telescopic rods (53); Finally, the bridge deck (4) is laid on the bridge end to form a complete combined system of the steel cofferdam and the steel trestle.

Images