Full penetration construction method for small-pipe-diameter intersecting line of half-through concrete-filled steel tube combined arch bridge

Abstract

The invention relates to a half-through concrete filled steel tube combined arch bridge small-pipe-diameter intersecting line full penetration construction method which comprises the following steps: step 1, establishing an intersecting line construction model, and cutting a steel tube intersecting line; step 2, assembling a steel pipe cross brace; step 3, welding a cross brace small-pipe-diameter intersecting line welding seam according to a welding process; 4, after welding operation is completed, ultrasonic waves are adopted for detecting a weld joint; according to the construction method, welding process parameters, the groove angle, the gap and the preheating temperature before welding are designed, full penetration of welding of the small-pipe-diameter intersecting line of the steel pipe combined arch bridge cross brace is achieved, the bridge structural strength is enhanced, and the adaptability to the structural space condition is improved.

Description

Technical Field

[0001] This invention relates to the field of welding technology, and in particular to a construction method for full penetration of small-diameter pipe intersection lines in a mid-span steel-concrete composite arch bridge. Background Technology

[0002] like Figure 1 As shown, the cross brace 1 of the 400km / h high-speed railway mid-span steel-concrete composite arch bridge is mainly used to bear the dynamic load of the 400km / h high-speed railway, achieving high load-bearing capacity and seismic stability through the steel-concrete composite structure. In conventional processes, because the diameter of the cross brace 1 pipe is less than 600mm, welding cannot be performed inside the pipe or the root canal cannot be cleaned due to the small internal space, resulting in lower structural strength and easy defects at the root. Furthermore, the cross brace 1 needs to be installed after the main arches 2 on both sides are installed, making it difficult to pre-install steel pads.

[0003] Therefore, this invention proposes a construction method for full penetration of small-diameter intersecting lines in a mid-span steel-concrete composite arch bridge to solve the above problems. Summary of the Invention

[0004] The technical problem to be solved by this invention is to provide a construction method for full penetration welding of small-diameter intersecting lines of cross braces in a mid-span steel-concrete composite arch bridge, thereby improving the adaptability to structural spatial conditions, achieving full penetration welding of small-diameter intersecting lines of cross braces in steel-concrete composite arch bridges, and enhancing the structural strength of the bridge.

[0005] To solve the above-mentioned technical problems, the technical solution of the present invention is: a construction method for full penetration of small-diameter intersecting lines in a mid-span steel-concrete composite arch bridge, the innovation of which lies in the following steps: Step 1: Establish a construction model for the intersection line and cut the steel pipe intersection line; Step 2: Assemble the steel pipe cross braces; Step 3: Weld the intersection weld of the small-diameter cross brace according to the welding process. The welding process includes: Step 3.1: Before welding, preheat the cross bracing steel pipe and the base steel pipe assembly at the weld joint using a flame or far-infrared heater; Step 3.2: Use CO2 gas shielded welding for the root pass, and submerged arc welding for the fill and cover passes. When welding intersecting welds, start the arc from the root and alternately weld symmetrically towards the toe. Use 1.2mm diameter T492T1-1C1A welding wire for both CO2 gas shielded welding and submerged arc welding. The process parameters for gas shielded welding root pass are: current 160±20A, voltage 26±2V, CO2 flow rate 15~20Lmin; The submerged arc welding process parameters are: current 180±20A, voltage 28±2V, CO2 flow rate 15~20Lmin; Step 4: After the welding operation is completed, use ultrasonic testing to inspect the weld.

[0006] Further, the toe is a groove with a value of 180-135° of β and 45-90° of α, a value of 2.0-5.0 mm of b, and a value of 0-2.0 mm of p; The root is a groove with a value of 75-30° of β and a value of 45° of α / 2, a value of 3.0-5.0 mm of b, and a value of 0-2.0 mm of p; Wherein, β is the angle between the axis of the cross brace steel pipe and the axis of the base steel pipe, α is the groove angle, b is the assembly gap, and p is the length of the bevel.

[0007] Further, in the preheating before welding in step 3.1, for the combination with a pipe thickness of ≤30 mm, the preheating temperature is ≥5℃, and the interpass temperature is 5-200℃; For the combination with a pipe thickness of >30 mm, the preheating temperature is 50-120℃, the preheating range is ≥100 mm in the range of the weld and both sides, and the interpass temperature is 80-200 mm.

[0008] Further, in step 3.1, the maximum pipe thickness of the cross brace steel pipe and the base steel pipe in the combination is taken as the pipe thickness of the combination.

[0009] Further, in step 3.1, for the combination with a pipe thickness of >30 mm, the temperature measuring point of the preheating temperature is located within 30-50 mm from the weld.

[0010] The application has the advantages that: The construction method of the application realizes full penetration of the intersecting line welding of the small pipe diameter of the cross brace of the steel pipe combined arch bridge, enhances the structural strength of the bridge, and improves the adaptability to the structural space conditions by controlling the welding process parameters.

[0011] The application designs the groove angle and the gap of the groove, ensures that the electric arc can extend into the root, avoids the incomplete penetration defect, optimizes the thickness of the bevel to prevent burn-through and ensure the penetration depth, and thus improves the controllability and operability of welding.

[0012] The application designs the preheating temperature before welding, can effectively reduce the welding stress and deformation, and improves the crack resistance and toughness of the weld. BRIEF DESCRIPTION OF DRAWINGS

[0013] The application will be further described in detail below in combination with the drawings and specific embodiments.

[0014] Figure 1 It is a structural schematic diagram of the half-through steel pipe concrete combined arch bridge of the application.

[0015] Figure 2 It is a schematic diagram of the section of the application. DETAILED DESCRIPTION

[0016] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with the accompanying drawings and preferred embodiments, is provided below.

[0017] Example This embodiment provides a construction method for full penetration of small-diameter pipe intersection lines in a mid-span steel-concrete composite arch bridge, including the following steps: Step 1: Establish a construction model for the intersection line and cut the steel pipe intersection line; Step 2: Assemble the steel pipe cross braces; Step 3: Weld the intersection weld of the small-diameter cross brace according to the welding process. The welding process includes: Step 3.1: Before welding, preheat the cross bracing steel pipe and the base steel pipe assembly at the weld joint using a flame or far-infrared heater; During preheating before welding, the maximum thickness of the cross bracing steel pipe and the base steel pipe in the assembly is taken as the combined pipe thickness. For assemblies with a pipe thickness ≤30mm, the preheating temperature is ≥5℃ and the interpass temperature is 5~200℃. For assemblies with a pipe thickness >30mm, the preheating temperature is 50~120℃, the preheating range is the weld and the area within ≥100mm on both sides, the interpass temperature is 80~200mm, and the temperature measurement point for the preheating temperature is located within 30~50mm of the weld. Step 3.2: Use CO2 gas shielded welding for the root pass, and submerged arc welding for the fill and cover passes. When welding intersecting welds, start the arc from the root and weld symmetrically and alternately towards the toe. ① Welding materials Both CO2 gas shielded welding and submerged arc welding use 1.2mm diameter T492T1-1C1A welding wire. Before welding, confirm that the welding wire and welding rod are correct, and clean the oil, rust and other dirt on the welding wire.

[0018] ② Bevel type and dimensions The toe region has a bevel with a β value of 180~135°, an α value of 45~90°, a b value of 2.0~5.0 mm, and a p value of 0~2.0 mm. The root has a bevel with a β value of 75~30° and a β / 2≤α value<45°, a b value of 3.0~5.0mm, and a p value of 0~2.0mm; Among them, such as Figure 2 As shown, β is the angle between the axis of the cross brace steel pipe and the axis of the parent material steel pipe, α is the bevel angle, b is the assembly clearance, and p is the blunt edge length.

[0019] ③ Welding process parameters: The process parameters for gas shielded welding root pass are: current 160±20A, voltage 26±2V, CO2 flow rate 15~20Lmin; The submerged-arc welding process parameters are: current 180±20 A, voltage 28±2 V, CO2 flow rate 15-20 L / min; Step 4: after the welding operation is completed, the weld is detected by using ultrasonic waves.

[0020] The small-pipe-diameter intersecting line full penetration construction method of the half-through steel pipe concrete composite arch bridge realizes the full penetration of the small-pipe-diameter intersecting line welding of the steel pipe composite arch bridge cross brace, enhances the structural strength of the bridge, and improves the adaptability to the structural space conditions.

[0021] The above description is only a preferred embodiment of the present application, and is not intended to limit the present application in any form. Although the present application has been disclosed as above with reference to the preferred embodiment, it is not intended to limit the present application. Any person skilled in the art can make some changes or modifications to the above disclosed technical content to obtain equivalent embodiments with equivalent changes, without departing from the technical solution of the present application. Any modification, change, equivalent change and modification of the above embodiments, which are made according to the technical essence of the present application, still belong to the scope of the technical solution of the present application.

Claims

1. A construction method for full penetration of small-diameter pipe intersection lines in a mid-span steel-concrete composite arch bridge, characterized by: Includes the following steps: Step 1: Establish a construction model for the intersection line and cut the steel pipe intersection line; Step 2: Assemble the steel pipe cross braces; Step 3: Weld the intersection weld of the small-diameter cross brace according to the welding process. The welding process includes: Step 3.1: Before welding, preheat the cross bracing steel pipe and the base steel pipe assembly at the weld joint using a flame or far-infrared heater; Step 3.2: Use CO2 gas shielded welding for the root pass, and submerged arc welding for the fill and cover passes. When welding intersecting welds, start the arc from the root and alternately weld symmetrically towards the toe. Use 1.2mm diameter T492T1-1C1A welding wire for both CO2 gas shielded welding and submerged arc welding. The process parameters for gas shielded welding root pass are: current 160±20A, voltage 26±2V, CO2 flow rate 15~20Lmin; The submerged arc welding process parameters are: current 180±20A, voltage 28±2V, CO2 flow rate 15~20Lmin; Step 4: After the welding operation is completed, use ultrasonic testing to inspect the weld.

2. The construction method for full penetration of small-diameter intersecting lines in a mid-span steel-concrete composite arch bridge according to claim 1, characterized in that: The toe portion has a bevel with a β value of 180~135°, an α value of 45~90°, a b value of 2.0~5.0mm, and a p value of 0~2.0mm; The root is a bevel with a β value of 75~30°, β / 2≤α value<45°, a b value of 3.0~5.0mm, and a p value of 0~2.0mm; Where β is the angle between the axis of the cross brace steel pipe and the axis of the parent material steel pipe, α is the bevel angle, b is the assembly clearance, and p is the length of the blunt side.

3. The construction method for full penetration of small-diameter intersecting lines in a mid-span steel-concrete composite arch bridge according to claim 1, characterized in that: In step 3.1, during preheating before welding, for combinations with a pipe thickness ≤30mm, the preheating temperature is ≥5℃ and the interpass temperature is 5~200℃. For combinations with a pipe thickness greater than 30 mm, the preheating temperature is 50~120℃, the preheating range is the weld seam and the area within ≥100 mm on both sides, and the interpass temperature is 80~200 mm.

4. The construction method for full penetration of small-diameter intersecting lines in a mid-span steel-concrete composite arch bridge according to claim 3, characterized in that: In step 3.1, the maximum thickness of the cross bracing steel pipe and the base steel pipe in the assembly is taken as the combined pipe thickness.

5. The construction method for full penetration of small-diameter intersecting lines in a mid-span steel-concrete composite arch bridge according to claim 4, characterized in that: In step 3.1, for combinations with a pipe thickness greater than 30 mm, the temperature measurement point for preheating is located within 30-50 mm of the weld.

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