Installation method of full-welding double-layer steel truss arch bridge related to navigation channel

Abstract

The application provides a kind of installation method of full-welding double-layer steel truss arch bridge related to historical and cultural protection and navigation channel, and the corresponding bridge type adopts three-span structure, and is provided with four main bridge piers, namely bridge piers P3, P4, P5 and P6, and the installation sequence of the main girder is to install the side span on both sides first, and then install the middle span, when the main girder is installed, the side span part above the historical and cultural protection area on land is assembled first, and then the middle span in the water area is assembled from the side span above the historical and cultural protection area as the starting point, the purpose is to protect the historical and cultural protection area first, and the upper main arch installation construction must be carried out after all the components of the main girder are installed and reliable permanent connection is formed, by using the double-layer structure characteristics of the main girder with upper and lower deck systems, the lower structure is installed and formed first, and the historical and cultural protection area is protected by using the lower structure as a protective barrier, the structure is fully utilized, and additional protection measures are avoided to cause secondary damage to the historical and cultural protection area.

Description

Technical Field

[0001] This invention relates to bridge construction technology, specifically to an installation method for a fully welded double-layer steel truss arch bridge involving cultural heritage and waterways. Background Technology

[0002] China is an ancient civilization with a long history and numerous World Heritage sites. The construction of some bridges inevitably requires crossing the protected areas of these World Heritage sites. For example, the newly built Grand Canal Bridge on the Beijing-Hangzhou Grand Canal is located within the protected area of ​​the Grand Canal (Hangzhou section). Since the Grand Canal was successfully inscribed on the World Heritage List in 2014, becoming China's 46th World Heritage site, the new bridge is situated within this protected area. The area extending 5 meters outward from the riverbanks on both the east and west sides of the canal is also within the protected area. Therefore, the bridge construction inevitably overlaps with the protected areas of the canal. How to protect these protected areas during construction and avoid damage to them has become a major challenge in the bridge's construction. Summary of the Invention

[0003] The present invention aims to solve at least one of the technical problems mentioned in the background art above, and provides a method for installing a fully welded double-layer steel truss arch bridge involving cultural relics and waterways, which can protect the cultural relics area during construction and avoid damage to the cultural relics area during construction.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0005] An installation method for a fully welded double-layer steel truss arch bridge involving cultural heritage protection and waterway protection is disclosed. The fully welded double-layer steel truss arch bridge includes main bridge piers, a main girder, and two main arches spaced apart along the transverse direction. The main bridge piers include piers P3, P4, P5, and P6, with piers P4 and P5 respectively located on the two banks of the river, and piers P4 and P5 positioned closer to their respective riverbanks. The area between pier P4 and its corresponding riverbank, and between pier P5 and its corresponding riverbank, constitutes a cultural heritage protection zone. The main girder includes two side spans located on land on both sides of the river and a side span located on the water. The bridge connects the two side spans to the middle span. Both the side spans and the middle span include several main beam segments connected in sequence. Each main beam segment includes two main truss sections, a node crossbeam connecting the two main truss sections, a lower bridge deck system, and an upper bridge deck system. The main truss sections are erected and fixed to the main bridge piers. The lower bridge deck system is erected and fixed to the bottom of the main truss sections, and the upper bridge deck system is erected and fixed to the top of the main truss sections. Both main arches are erected and fixed to the main truss sections of the main beam, and the two main arches are fixedly connected by cross bracing. The main arches are connected to the main truss sections of the main beam by suspension cables. The installation method of the fully welded double-layer steel truss arch bridge includes the following steps:

[0006] S1, Erect temporary piers on the shore and in the water: Erect temporary piers on the shore between piers P3 and P4 and between piers P5 and P6 to form an onshore assembly platform, and erect temporary piers in the water area of ​​the river to form a water assembly platform, and simultaneously complete the assembly of the main girder truss segments, the lower bridge deck system and the upper bridge deck system.

[0007] S2, Main beam installation: The main beam is installed in situ on both the shore and water assembly platforms. During installation, the side spans above the cultural heritage protection area are assembled first, and the remaining side spans are assembled from the cultural heritage protection area toward the direction away from the river channel. At this time, the crawler crane used for assembly is located on land. Then, the middle span in the water area is assembled, and the crawler crane is transferred to the assembled upper bridge deck system. The upper bridge deck system is assembled from the cultural heritage protection area toward the middle of the bridge until the bridge is closed. The installation sequence of the main beam segments of the side spans and the middle span is the same: main truss segment → lower bridge deck system → upper bridge deck system.

[0008] S3, Main arch support installation: After the main beam is installed, the main arch support is installed directly on the assembled upper bridge deck using a crawler crane. The main arch support is used to temporarily support the main arch during the main arch installation process.

[0009] S4, Main Arch Assembly: During the construction of the main beam, several main arch segments that constitute the main arch are assembled simultaneously.

[0010] S5, Main Arch Installation: Two crawler cranes are used to hoist the main arch segments from both sides of the bridge toward the middle in a synchronous and symmetrical manner on the assembled upper bridge deck until the bridge is closed. During the main arch installation process, the cross bracing connecting the two main arches is installed simultaneously.

[0011] S6, Temporary structure removal and construction completion: After the main arch is installed, the entire bridge is installed and the temporary structure is removed. First, the main arch support is removed, the suspension cables are tensioned, and then the temporary piers in the water and on the shore are removed.

[0012] Furthermore, in step S2, both the lower and upper bridge deck systems are assembled by sequentially welding several bridge deck units. Each bridge deck unit includes a bridge deck, several spaced main crossbeams, and several spaced secondary crossbeams. The main crossbeams and secondary crossbeams are welded to the bottom surface of the bridge deck. The main crossbeams and secondary crossbeams extend along the transverse direction of the bridge, and several secondary crossbeams are provided between adjacent main crossbeams. The width of each bridge deck unit is 2m to 3.9m.

[0013] Furthermore, the installation method of the lower bridge deck system and the upper bridge deck system in step S2 is as follows: For the installation of bridge deck units above the river channel and cultural heritage protection areas, before hoisting, the bridge decks of several bridge deck units are widened to obtain a plate with a width of 15±2 meters. Then, the secondary crossbeams of several bridge deck units are welded onto the plate to form an ultra-wide flexible bridge deck hoisting assembly. During installation, the main crossbeams of several bridge deck units are first hoisted to the preset installation position of the main truss plate by crawler crane for welding installation. Then, the bridge deck hoisting assembly is hoisted to the preset installation position and installed and connected to the main crossbeam by crawler crane.

[0014] Furthermore, the main truss segment includes an upper chord, a lower chord, node plates, and several web members. The upper chord and the lower chord are arranged vertically at relative intervals. Node plates connected to the web members are welded and fixed to the inner surfaces of both the upper chord and the lower chord. Several web members are arranged sequentially along the length of the main truss segment, with each web member's opposite ends welded and fixed to the node plates of the upper chord and the lower chord, respectively. The lower chord length of the main truss segment above the cultural heritage protection area reaches 30m, and the lower chord length of the main truss segment above the navigable water area reaches 40m.

[0015] Furthermore, for the main truss segment above the cultural heritage protection area, its lower chord is provided with three node plates spaced apart along its length; for the main truss segment above the navigable area in the water, its upper chord is provided with four node plates spaced apart along its length.

[0016] Furthermore, in step S2, for the main truss segments above the navigable area in the water, the main truss segments are hoisted in a piecemeal state; for the main truss segments above the cultural heritage protection area, the main truss segments are hoisted in a half-truss segment state; for the main truss segments above the cultural heritage protection area and the non-navigable area, the main truss segments are hoisted in a truss segment state.

[0017] Furthermore, when hoisting the main truss segments in a piecemeal manner, crawler cranes are used to hoist the upper chord, lower chord, node plates, and web members of the main truss segments to the preset installation positions before welding and assembly.

[0018] Furthermore, when hoisting the main truss segment in a half-truss segment state, the upper chord and the corresponding web members are first welded and assembled into at least half-truss segment structure. Then, the lower chord of the main truss segment and the corresponding half-truss segment structure are hoisted to the preset installation position by a crawler crane and then welded and assembled.

[0019] Furthermore, when hoisting the main truss segments in the form of truss segments, the upper chord, web members, and lower chord are first welded and assembled into the main truss segments. Then, a crawler crane is used to hoist the main truss segments as a whole to the preset installation position, and then they are welded and assembled with other main truss segments.

[0020] Furthermore, in step S2, for the installation of the side span, the crawler crane is positioned on the ground, and one of the main beam segments is installed as the reference segment, starting from piers P4 and P5. Then, starting from the reference segment, the corresponding side span part above the cultural heritage protection area is assembled. The remaining main beam segments of the side span are installed from the reference segment towards piers P3 or P6.

[0021] By adopting the above technical solution, the present invention has the following beneficial effects:

[0022] 1. The above-mentioned installation method for the fully welded double-layer steel truss arch bridge involving cultural relics and waterways adopts a three-span structure with four main bridge piers, namely piers P3, P4, P5, and P6. The installation sequence of the main beams is to first install the side spans on both sides, and then install the middle span. During the installation of the main beams, the side spans above the cultural relics protection area on land are assembled first, and then the middle span in the water area is assembled starting from the side spans above the cultural relics protection area. The purpose is to prioritize the protection of the cultural relics protection area. It is required that the installation of the upper main arch should only be carried out after all the components of the main beam are installed and a reliable permanent connection is formed. Taking advantage of the double-layer structure of the main beam with upper and lower bridge deck systems, the lower structure is installed first and used as a protective barrier to protect the cultural relics protection area. While making full use of its own structure, it avoids secondary damage to the cultural relics protection area caused by adding additional protective measures.

[0023] 2. The above-mentioned installation method for the fully welded double-layer steel truss arch bridge involving cultural relics and waterways includes three main truss installation methods: truss segment, half-truss segment, and loose assembly. This method realizes the transition from half-truss segment to truss segment and from half-truss segment to loose assembly during the installation of the main truss segments. It provides more possibilities for the installation method of fully welded steel truss bridges under restricted conditions. Under the premise of avoiding secondary damage to the cultural relics protection area by adding additional protective measures, it meets the stress requirements of the assembly platform and the lifting weight requirements of the crawler crane, thereby improving construction safety.

[0024] 3. Currently, the main truss segments in China are mainly installed using a piecemeal assembly method. In this method, the chords of the main truss segments are mostly single-node or double-node. The aforementioned installation method for the fully welded double-layer steel truss arch bridge involving cultural relics and waterways uses a 40m long four-node lower chord with four node plates for the main truss segments corresponding to the navigation area, and a 30m long three-node lower chord with three node plates for the cultural relics protection area. This method can achieve a complete crossing of both the navigation area and the cultural relics protection area, avoiding spatial overlap between the construction area and the navigation area or the cultural relics protection area. Furthermore, the centralized construction method reduces the frequency of lower chord lifting and minimizes the impact on navigation and the cultural relics protection area.

[0025] 4. In general construction methods, the bridge deck is first welded to the main and secondary crossbeams to form bridge deck blocks, which are then hoisted and installed as a whole. These blocks are heavy, and due to the presence of the main crossbeams, they have high rigidity, requiring sophisticated hoisting equipment. Tracked cranes cannot be used. Current technology typically uses floating cranes on the river, but this requires closing the navigation area; alternatively, a completely piecemeal approach is used, which doesn't create 15m wide panel units for installation. However, this involves numerous hoisting operations, slow construction efficiency, poor overall integrity, and significant impacts and potential hazards to cultural heritage preservation and navigation. Therefore, the above-mentioned installation method for a fully welded double-layer steel truss arch bridge involving cultural heritage preservation and navigation is proposed to address this issue. To minimize the impact on cultural heritage preservation and navigation, the bridge deck units are first connected to a width of approximately 15m before hoisting. The secondary crossbeams are then welded onto the bridge deck to form an ultra-wide flexible bridge deck unit. This unit is then installed as a whole and connected to the main crossbeams. The resulting flexible bridge deck unit is lighter than the bridge deck blocks and has greater flexibility, reducing the limits of hoisting equipment. Tracked cranes can be used to hoist it onto the assembled bridge deck without closing the waterway. Furthermore, the ultra-wide flexible bridge deck unit has good overall integrity and is easy to connect. Unlike traditional small, scattered bridge deck units, it does not require frequent hoisting and positioning. These characteristics of the ultra-wide flexible bridge deck unit make it particularly advantageous for bridge deck installation under restricted conditions.

[0026] Therefore, the above-mentioned installation method for fully welded double-layer steel truss arch bridges involving cultural relics protection and waterway navigation can solve the installation and erection problems of fully welded double-layer steel truss arch bridges under the dual influence of cultural relics protection and waterway navigation, under the premise of economy and efficiency. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the structure of a fully welded double-layer steel truss arch bridge involving cultural relics and waterways, according to a preferred embodiment of the present invention.

[0028] Figure 2 for Figure 1 The diagram shows the hoisting status of the main truss segments and the main arch segments in the fully welded double-layer steel truss arch bridge.

[0029] Figure 3 for Figure 2 A structural diagram showing the structure of one of the main truss segments in the segment state;

[0030] Figure 4 for Figure 2 A structural diagram showing the structure of one of the main trusses in a half-truss state;

[0031] Figure 5 for Figure 2 A structural diagram of one of the main truss segments when it is in a disassembled state;

[0032] Figure 6 for Figure 1 The diagram shows the structural schematic of the bridge deck unit in the fully welded double-layer steel truss arch bridge.

[0033] Figure 7 for Figure 2 A diagram showing the hoisting status of the main arch segment located above the cultural relic protection area;

[0034] Figures 8-13 This is a schematic diagram of the installation of the side span;

[0035] Figures 14-17 This is a schematic diagram of the installation in the middle span.

[0036] Figures 18-19 The diagram shows the installation of the main arch; the letters in the attached diagram are the numbers of the various components during construction.

[0037] Explanation of main component symbols

[0038] 10. Main bridge pier; 20. Main girder; 21. Side span; 23. Mid-span; 24. Main girder segment; 25. Main truss; 251. Top chord; 252. Bottom chord; 253. Node plate; 254. Web member; 26. Lower deck system; 27. Upper deck system; 28. Bridge deck unit; 281. Bridge deck; 282. Main crossbeam; 283. Secondary crossbeam; 284. Longitudinal beam; 30. Main Arch; 31. Upper arch rib; 32. Lower arch rib; 33. Truss arch assembly; 331. Arch starting section; 332. Segment between arch beams; 334. Upper arch segment; 335. Closing section; 33. Web tube; 35. Horizontal brace; 40. Node beam; 50. Suspension cable; 60. Area involving cultural heritage protection; 70. Navigation area; 81. Temporary pier on shore; 83. Temporary pier in water; 90. Main arch support; 100. Crawler crane. Detailed Implementation

[0039] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0040] It should be noted that when a component is described as "fixed to" another component, it can be directly on the other component or may have a component in between. When a component is considered "connected to" another component, it can be directly connected to the other component or may have a component in between. When a component is considered "set on" another component, it can be directly set on the other component or may have a component in between. The terms "vertical," "horizontal," "left," "right," and similar expressions used in this document are for illustrative purposes only.

[0041] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0042] Please see Figure 1 A preferred embodiment of the present invention provides an installation method for a fully welded double-layer steel truss arch bridge involving cultural heritage protection and waterway. The fully welded double-layer steel truss arch bridge includes a main bridge pier 10, a main beam 20 erected on the main bridge pier 10, and two main arches 30 erected on opposite sides of the main beam 20 along the transverse direction of the bridge.

[0043] The main bridge piers 10 include four piers: P3, P4, P5, and P6. Piers P4 and P5 are located on the two banks of the river, with piers P4 and P5 being closer to the river. The area between pier P4 and its corresponding bank, and between pier P5 and its corresponding bank, is a cultural protection zone 60, with the river corresponding to the water area.

[0044] The fully welded double-layer steel truss arch bridge in this embodiment is a three-span fully welded plate truss combined with integral node plate truss bridge. The main girder 20 adopts a three-span structure, including two side spans 21 located on the land area on both sides of the river channel and a middle span 23 located above the water area and connecting the two side spans 21. Please refer to [further details omitted]. Figure 2 Both the side span 21 and the middle span 23 include several main beam segments 24 connected in sequence. Each main beam segment 24 includes two main truss pieces 25 and a node beam 40 connecting the two main truss pieces 25. Figure 10The bridge consists of a lower deck system 26 and an upper deck system 27. The main truss segments 25 are erected and fixed to the main bridge piers 10. The lower deck system 26 is erected and fixed to the bottom of the main truss segments 25, and the upper deck system 27 is erected and fixed to the top of the main truss segments 25. Two main arches 30 are opposite each other in the transverse direction and erected and fixed to the top of the main truss segments 25. The two main arches 30 are fixedly connected by cross braces 35. The main arches 30 are also connected to the main truss segments 25 of the main beam 20 by suspension cables 50.

[0045] The main truss segment 25 is the most important load-bearing member of the entire bridge. In this embodiment, each main girder segment 24 has two main truss segments 25 along the transverse direction. Please refer to [the relevant documentation / reference]. Figure 3 Each main truss segment 25 includes an upper chord 251, a lower chord 252, a node plate 253, and several web members 254. The upper chord 251 and the lower chord 252 are arranged vertically at intervals. The inner surfaces of the upper chord 251 and the lower chord 252 are welded and fixed with node plates 253 connected to the web members 254. Several web members 254 are arranged sequentially along the length of the main truss segment 25. The two ends of each web member 254 are welded and fixed to the node plates 253 of the upper chord 251 and the lower chord 252, respectively. Furthermore, in this embodiment, for the main truss segment 25 above the cultural heritage protection area 60, the length of a single lower chord 252 reaches 30m, and three node plates 253 are provided on the lower chord 252 at intervals along its length direction; for the main truss segment 25 above the navigable area 70 in the water, the length of a single lower chord 252 reaches 40m, and four node plates 253 are provided on the lower chord 252 at intervals along its length direction. One or two node plates 253 are provided on the remaining lower chords 252 and the upper chords 251 of the main truss segment 25. The upper chords 251 of the two main truss segments 25 and the lower chords 252 of the two main truss segments 25 are connected by node beams 40.

[0046] Please see also Figure 6 In this embodiment, the lower bridge deck system 26 and the upper bridge deck system 27 have the same structure. Both the lower bridge deck system 26 and the upper bridge deck system 27 are assembled by welding together several bridge deck units 28. Each bridge deck unit 28 includes a bridge deck 281, several spaced-apart main crossbeams 282, several spaced-apart secondary crossbeams 283, and several spaced-apart longitudinal beams 284. The main crossbeams 282, secondary crossbeams 283, and longitudinal beams 284 are all welded to the bottom surface of the bridge deck 281. The main crossbeams 282 and secondary crossbeams 283 extend in the transverse direction of the bridge, and the longitudinal beams 284 extend in the longitudinal direction of the bridge and are welded and fixed to the main crossbeams 282 or secondary crossbeams 283. A secondary crossbeam 283 and a longitudinal beam 284 are provided between two adjacent main crossbeams 282. The width of each bridge deck unit 28 is 2m to 3.9m.

[0047] In this embodiment, the main arch 30 is erected and fixed to the top of the upper chord 251 of the main truss segment 25. Each main arch 30 is a truss arch system composed of upper and lower arch ribs 31 and 32. The upper arch rib 31 and the lower arch rib 32 are connected by a web tube 33 to form a triangular truss. The upper arch rib 31, the lower arch rib 32, and the web tube 33 are all connected by welding. Each main arch 30 includes two truss arch components 33 symmetrically arranged along the center line of the bridge span and a closing section 335 connecting the two truss arch components 33. Each truss arch component 33 includes several main arch segments that are sequentially spliced ​​by welding along the direction close to the river. In this embodiment, the main arch segment includes several arch-starting segments 331, arch-beam segments 332, and arch-top segments 334 that are sequentially spliced ​​by welding along the direction close to the river. The closing section 335 connects the free ends of the arch-top segments 334 of the two truss arch components 33.

[0048] In this embodiment, the cross brace 35 is located approximately at the center of the main arch 30. The upper arch ribs 31 of the two main arches 30 and the lower arch ribs 32 of the two main arches 30 are connected together by the cross brace 35. The suspension cables 50 are high-strength epoxy-coated steel wire cables with double-layer, double-sheathed high-density polyethylene sheaths and a tensile strength of 1770 MPa. They are arranged approximately at the center of the main arch 30, with both ends of each suspension cable 50 anchored to the lower arch rib 32 of the main arch 30 and the upper chord 251 of the main truss section 25 of the main beam 20, respectively. In this embodiment, the suspension cables 50 are arranged with a single cable plane on both sides. The axis of the suspension cables 50 is not plumb, but rather follows the line connecting the web tube node of the main arch 30 and the web member node of the upper chord 251 of the main truss section 25. Considering the convenience of construction tensioning and future cable replacement, the beam-mounted tensioning method is used for construction.

[0049] The installation method of the fully welded double-layer steel truss arch bridge includes the following steps:

[0050] S1, please refer to Figure 8 Temporary piers 81 on the shore and temporary piers 83 in the water are erected: Temporary piers 81 on the shore are erected between piers P3 and P4 and between piers P5 and P6 to form an onshore assembly platform. Temporary piers 83 in the water are erected in the water area of ​​the river to form an underwater assembly platform. The main truss 24, upper bridge deck system 27 and lower bridge deck system 26 of the main beam 20 are assembled simultaneously.

[0051] In this embodiment, the structures of the temporary piers 81 on the shore and 83 in the water are existing technologies and will not be described in detail here for brevity. Since construction is not permitted in the cultural heritage protection zone 60, it is impossible to install temporary piers or other supporting devices or protective devices for construction within the cultural heritage protection zone 60.

[0052] S2, Install the main beam 20: The main beam 20 is assembled in situ. The main beam 20 is installed on the onshore assembly platform and the water assembly platform. During installation, the side span 21 part above the cultural heritage protection area 60 is assembled first. The remaining side span 21 parts are assembled from the cultural heritage protection area 60 towards the direction away from the river channel. At this time, the crawler crane 100 used for assembly is located on land. Then the middle span 23 in the water area is assembled. The crawler crane 100 is transferred to the assembled upper bridge deck system 27 and assembled from the cultural heritage protection area 60 towards the middle of the bridge until the bridge is closed. The installation sequence of the main beam segments 24 of the side spans 21 and the middle span 23 is the same: main truss segment 25 → lower bridge deck system 26 → upper bridge deck system 27.

[0053] In this embodiment, the bridge deck width is approximately 30m. All bridge deck units 28 are manufactured in the factory with a width of 2m to 3.9m. To reduce the impact on cultural heritage preservation and navigation, in step S2, before hoisting, the bridge decks 281 of several bridge deck units 28 are widened to obtain a plate with a width of 15±2 meters. Then, the secondary crossbeams 283 of several bridge deck units 28 are welded onto the plate to form an ultra-wide flexible bridge deck hoisting assembly. During installation, the main crossbeams 282 of several bridge deck units 28 are first hoisted to the preset installation position of the main truss plate 2 by the crawler crane 100 for welding and installation. Then, the bridge deck hoisting assembly is hoisted to the preset installation position and connected to the main crossbeams 282 by the crawler crane 100. Finally, the longitudinal beams 284 are installed.

[0054] Furthermore, in step S2, the main truss segment 25 above the river channel is hoisted in a piecemeal assembly manner; such as Figure 5 As shown, when hoisting the main truss segment 25 in a disassembled state, the crawler crane 100 is used to hoist the upper chord 251, lower chord 252, node plate 253, and web member 254 of the main truss segment 25 to the preset installation position before welding and assembly. For the main truss segment 25 above the cultural heritage protection area 60, the segment is hoisted in a half-segment state, such as... Figure 4 As shown, when hoisting the main truss segment 25 in a semi-truss configuration, the upper chord 251 and the corresponding web member 254 are first welded together to form a semi-truss structure. Then, the crawler crane 100 is used to hoist the lower chord 252 and the semi-truss structure of the main truss segment 25 to the preset installation position before welding and assembly. For the main truss segment 25 located above the non-cultural heritage protection area 60 and the non-navigation area 70, the main truss segment 25 is hoisted in a truss configuration, as follows: Figure 3 As shown, when hoisting the truss segment in the form of a truss segment, the upper chord 251, web member 254 and lower chord 252 are first welded and assembled into the main truss segment 25. Then, the crawler crane 100 is used to hoist the main truss segment 25 as a whole to the preset installation position, and then it is welded and assembled with other main truss segments 25.

[0055] In this embodiment, in step S2, for the installation of the side span 21, the crawler crane 100 stands on the ground and installs one of the main beam segments 24 as a reference segment, starting from piers P4 and P5. Then, starting from the reference segment, the corresponding part of the side span 21 above the cultural heritage protection area 60 is assembled. The remaining main beam segments 24 of the side span 21 are installed from the reference segment towards piers P3 or P6. For the middle span 23, the crawler crane moves to the assembled upper bridge deck and installs from the cultural heritage protection area 60 towards the middle of the span. Specifically, it may include the following steps:

[0056] S21, as Figure 8 As shown, one of the main beam segments 24 of the side span 21 is first installed on piers P4 and P5 as the reference segment.

[0057] S22, as Figures 9 to 11 As shown, the main beam segment 24 of the side span 21 above the cultural heritage protection area 60 is installed. Specifically, firstly, the three-node lower chord 252 corresponding to the cultural heritage protection area 60 is hoisted onto piers P4 and P5 and the temporary underwater pier 83 close to piers P4 and P5 using a crawler crane 100 on the ground. Because the three-node lower chord 252 is relatively long, it can directly cross the cultural heritage protection area 60, reducing its impact on the cultural heritage protection area 60. Then, the remaining parts of the main beam segment 24 corresponding to the cultural heritage protection area 60, such as the half-truss structure, are hoisted and installed sequentially using the crawler crane 100 on the ground. The installation sequence of the main beam segment 24 is main truss segment 25 → lower bridge deck system 26 → upper bridge deck system 27. During the hoisting of the main truss segment 25, at least some node crossbeams 40 are installed simultaneously.

[0058] S23, install the remaining main beam segments 24 of the side span 21, such as Figure 12 As shown, specifically, the remaining main beam segments 24 of the side span 21 are installed segment by segment from the cultural heritage protection area 60 toward the side span 21. The installation sequence of each main beam segment 24 is main truss plate 25 → lower bridge deck system 26 → upper bridge deck system 27, until the entire side span 21 is installed. During the hoisting of the main truss plate 25, the node crossbeams 40 are installed simultaneously.

[0059] In this embodiment, each main girder segment 24 is first installed with the main truss plate 25 and the node crossbeam 40. Then, the main crossbeam 282 of the lower bridge deck system 26 is installed on the main truss plate 25. After that, the flexible bridge deck hoisting assembly and longitudinal beam 284 of the lower bridge deck system 26 are installed. Then, the main crossbeam 282 of the upper bridge deck system 27 is installed on the main truss plate 25. Finally, the flexible bridge deck hoisting assembly and longitudinal beam 284 of the upper bridge deck system 27 are installed. Furthermore, for the installation of the main girder segment 24 of the side span 21 above the non-cultural heritage protection area 60, since the land area of ​​the non-cultural heritage protection area 60 can be supported by installing temporary piers, the main truss plate 25 can be hoisted and installed as a whole, which can improve construction efficiency.

[0060] In this embodiment, since temporary piers or other supporting structures cannot be installed in the cultural heritage protection area 60, resulting in weak load-bearing capacity, this embodiment first installs the main beam segment 24 above the cultural heritage protection area 60. During installation, the lower chord 252 of the main beam segment 24 above the cultural heritage protection area 60 is installed first, followed by the installation of the semi-truss structure of the main beam segment 24 above the cultural heritage protection area 60. For example, in this embodiment, the lower chord 252 of the main beam segment 24 above the cultural heritage protection area 60 adopts a structure with three sections. The three-node lower chord 252 of the gusset plate 253 and the upper chord 251 of the main beam segment 24 above the cultural heritage protection area 60 include a two-node upper chord 251 with two node plates 253 and a one-node upper chord 251 with one node plate 253. The upper chords 251 are connected to the corresponding web members 254 to form a semi-truss structure. During installation, the lower chord 252 is installed first, followed by the semi-truss structure. Compared to installing the entire truss structure, this significantly reduces the stress requirements on the assembly platform. Furthermore, to further reduce the stress on the simply supported structure, when installing the main beam segment 24 corresponding to the cultural heritage protection area 60, only some of the lighter node crossbeams 40 can be installed first. The heavier node crossbeams 40 can be installed after the remaining side spans 21 are installed, with the crawler crane 100 positioned on the upper bridge deck. Figure 11 As shown, in this embodiment, the node beam 40 at node A9A10 has the greatest weight. It is not installed during the installation of the main beam segment 24 corresponding to the protected cultural relic area 60. The node beam 40 at node A9A10 and the corresponding upper bridge deck system 27 will be installed after the other side spans 21 are installed. Figure 13 ).

[0061] S24, move the crawler crane 100 onto the bridge deck 281 of the assembled upper bridge deck system 27, and install several main beam segments 24 of the middle span 23. Specifically, starting from the cultural heritage protection area 60, continue installing several main beam segments 24 of the middle span 23 towards the mid-span until the closure position is reached. Figures 14 to 17As shown.

[0062] In this embodiment, a crawler crane 100 is used to hoist and install the middle span 23 on the bridge deck 281 of the upper bridge deck system 27. Compared with the floating crane method, this method does not require long-term navigation closure and has less impact on the navigation area 70. In addition, this embodiment uses a piecemeal assembly method to hoist and install the main truss segments 25 of the middle span 23, which further reduces the requirements for the lifting weight of the hoisting equipment, allowing the crawler crane 100 of the upper bridge deck system 27 to complete the hoisting of the main truss segments 25 of the middle span 23.

[0063] In this embodiment, the main truss segments 25 of the middle span 23 are hoisted and installed in a piecemeal manner. The installation sequence of the main truss segments 25 of the middle span 23 is: lower chord 252 → web members 254 → upper chord 251. During the hoisting of the main truss segments 25, the node crossbeams 40 are installed simultaneously. Then, the corresponding lower deck system 26 and upper deck system 27 are installed. The installation sequence of the lower deck system 26 is as follows: first, the main crossbeams 282 of the bridge deck unit 28 of the lower deck system 26 are installed on the main truss segments 25, and then the flexible bridge deck hoisting components and longitudinal beams 284 of the lower deck system 26 are installed. The installation sequence of the upper deck system 27 is as follows: first, the main crossbeams 282 of the bridge deck unit 28 of the upper deck system 27 are installed on the main truss segments 25, and then the flexible bridge deck hoisting components and longitudinal beams 284 of the upper deck system 27 are installed.

[0064] S25, Closure of Main Beam 20: The main beam segment 24 at the closure position of the main beam 20 is transported to the closure water area by ship (e.g., Figure 16 and 17 As shown, two crawler cranes 100 are used to simultaneously lift and install the main beam at the closure position from both sides. The crawler cranes 100 are positioned on the bridge deck 281 of the installed upper bridge deck system 27. Navigation needs to be closed during the lifting process, with two closures required upstream and downstream, each lasting approximately 6 hours. The main beam segment 24 at the closure position of the main beam 20 is installed by hoisting the main truss 25 in a piecemeal manner. The installation sequence of the main truss 25, the upper bridge deck system 27, and the lower bridge deck system 26 is the same as in step S24, and will not be repeated here for brevity.

[0065] In this embodiment, the main beam segment 24 at the closure position of the main beam 20 adopts a 40-meter-long four-node lower chord 252, which can cross the navigation area 70 in the water in one go, reducing the time of navigation closure.

[0066] S3, Main arch support 90 installation: (as shown) Figure 18 As shown, after the main beam 20 is installed, the crawler crane 100 is used to install the main arch support 90 on the bridge deck 281 of the upper bridge deck system 27. The main arch support 90 is used to temporarily support the main arch 30 during the installation of the main arch 30.

[0067] In this embodiment, after the main beam 20 is installed in place, a steel pipe support is erected on the bridge deck 281 of the upper bridge deck system 27 as the main arch support 90. The main arch support 90 is used to temporarily support the main arch 30. The construction of the main arch support 90 is prior art and will not be described in detail here for the sake of brevity.

[0068] S4, main arch 30 assembly: as shown Figure 18-19 As shown, during the construction of the main beam 20, the various main arch segments of the main arch 30 are assembled simultaneously, that is, the rods and other components that make up the main arch segments are connected together by welding to form the main arch segments.

[0069] In this embodiment, the arch-starting section 331 of the main arch 30 is assembled in a single-piece manner, while the remaining main arch segments are assembled in a continuous matching manner.

[0070] S5, Main Arch 30 Installation: Two crawler cranes 100 are used to synchronously and symmetrically lift the main arch segments of the main arch 30 from both sides of the bridge towards the middle on the bridge deck 281 of the upper bridge deck system 27 until the bridge is closed. During the installation of the main arch segments, the cross bracing 35 connecting the two main arches 30 is installed simultaneously.

[0071] In this embodiment, step S5 specifically includes the following steps:

[0072] S51, using two crawler cranes 100, the arch-raising section 331 of the main arch segment is simultaneously and symmetrically lifted from both sides of the bridge deck 281 of the constructed upper bridge deck system 27 towards the middle of the bridge, thus completing the installation of the arch-raising section 331.

[0073] S52, starting from the arch-raising section 331, the arch beam segments 332 and the upper arch segments 334 of the main arch segment are installed sequentially on the main arch support 90 facing the river channel, until the closure position. Upon completion of each main arch segment installation, the cross bracing 35 is installed synchronously. In this embodiment, the cross bracing 35 is made by extending φ478 steel pipes before hoisting and installation.

[0074] Please see again Figure 2 and Figure 7In this embodiment, the upper arch segment 334 above the cultural heritage protection area 60 is located at the connection between the main arch 33 and the main beam 20. It is the heaviest and bears the greatest force. To ensure the installation accuracy of this segment, in this embodiment, the installation method of the upper arch segment 334 above the cultural heritage protection area 60 is as follows: Before hoisting, the upper arch rib 31 of the upper arch segment 334 is connected to the web tube 33 to obtain an assembly. During hoisting, the lower arch rib 32 of the upper arch segment 334 is hoisted and installed first. After the lower arch rib 32 of the upper arch segment 334 is connected to the upper chord tube 251 of the main beam 20, the assembly of the upper arch rib 31 and the web tube 33 of the upper arch segment 334 is hoisted, and the web tube 33 of the assembly is connected to the lower arch rib 32 of the upper arch segment 334. It can improve the installation accuracy of the arch segment 334 corresponding to the 60 above the cultural heritage protection area, and reduce the number of hoisting operations, thereby improving construction efficiency.

[0075] S53, install the closure section 335 of the main arch 30.

[0076] S6, Temporary structure removal, construction completed: After the main arch 30 is installed, the entire bridge is installed and the temporary structure is removed. First, the main arch support 90 and tensioning cable 50 are removed, and then the temporary pier 83 in the water and the temporary pier 81 on the shore are removed.

[0077] The aforementioned installation method for the fully welded double-layer steel truss arch bridge involving cultural relics and waterways adopts a three-span structure with four main bridge piers 10, namely piers P3, P4, P5, and P6. The installation sequence of the main beam 20 is as follows: first, install the side spans 21 on both sides, and then install the middle span 23. During the installation of the main beam 20, first assemble the side span 21 above the cultural relics protection area 60 on land, and then assemble the middle span 23 in the water area starting from the side span 21 above the cultural relics protection area 60. The purpose is to prioritize the protection of the cultural relics protection area 60. It is required that the installation of the upper main arch 30 should only be carried out after all components of the main beam 20 are installed and a reliable permanent connection is formed. Taking advantage of the double-layer structure of the main beam 20 with upper and lower bridge deck systems, the lower structure is installed first and used as a protective barrier to protect the cultural relics protection area 60. This fully utilizes the structure itself and avoids secondary damage to the cultural relics protection area 60 caused by additional protective measures.

[0078] The aforementioned installation method for the fully welded double-layer steel truss arch bridge involving cultural relics and waterways includes three main truss installation states for the main truss segments 25: truss segments, half-truss segments, and loose assembly. This method facilitates the transition of the main truss segments 25 from half-truss segments to truss segments and from half-truss segments to loose assembly during installation. It provides more possibilities for the installation of fully welded steel truss bridges under restricted conditions, and while avoiding secondary damage to the cultural relics protection area 60 caused by additional protective measures, it meets the stress requirements of the assembly platform and the lifting capacity of the crawler crane, thereby improving construction safety.

[0079] Currently, the main truss segments in China are mainly installed using a piecemeal assembly method. In this method, the chords of the main truss segments are mostly single-node or double-node. The aforementioned installation method for the fully welded double-layer steel truss arch bridge involving cultural relics and waterways uses a 40m long four-node lower chord with four node plates for the main truss segment 25 corresponding to the navigation area 70, and a 30m long three-node lower chord with three node plates for the cultural relics protection area 60. This method enables the overall crossing of both the navigation area 70 and the cultural relics protection area 60, avoiding spatial overlap between the construction area and the navigation area 70 or the cultural relics protection area 60. Furthermore, the centralized construction method reduces the frequency of lower chord hoisting and minimizes the impact on navigation and the cultural relics protection area.

[0080] In general construction methods, the bridge deck 281 is first welded to the main crossbeam 282 and secondary crossbeam 283 to form bridge deck blocks before being hoisted and installed as a whole. This method is quite heavy, and the bridge deck blocks, due to the presence of the main crossbeams, have high rigidity, requiring sophisticated hoisting equipment. Tracked cranes cannot be used for this purpose. Existing technologies typically use floating cranes on the river, however, this requires closing the navigation area 70; alternatively, a completely piecemeal approach is used, which doesn't create 15m wide panel units for installation. However, this involves numerous hoisting operations, slow construction efficiency, poor overall integrity, and significant impacts and potential hazards to cultural heritage preservation and navigation. The aforementioned installation method for a fully welded double-layer steel truss arch bridge involving cultural heritage preservation and navigation requires addressing these issues to reduce the impact on... Due to the impact of cultural heritage preservation and navigation, before hoisting, the bridge deck unit 28 is first connected to a width of about 15m, and the secondary crossbeam 283 is welded to the bridge deck 281 to form an ultra-wide flexible bridge deck unit. After the whole unit is installed, it is connected to the main crossbeam 282. The resulting flexible bridge deck unit is lighter than the bridge deck block and has great flexibility, which can reduce the limit of hoisting equipment. A crawler crane 100 can be used to hoist it on the spliced ​​bridge deck without closing the navigation. Moreover, the ultra-wide flexible bridge deck unit has good integrity and is easy to connect. Unlike traditional scattered small bridge deck units, it does not require frequent hoisting and positioning. The above characteristics of the ultra-wide flexible bridge deck unit make it particularly advantageous for bridge deck installation under restricted conditions.

[0081] Therefore, the installation method of the fully welded double-layer steel truss arch bridge involving cultural relics protection and waterway navigation in this embodiment can solve the installation and erection problem of fully welded double-layer steel truss arch bridge under the dual influence of cultural relics protection and waterway navigation, under the premise of economy and efficiency.

[0082] The above description is a detailed description of the preferred embodiments of the present invention. However, the embodiments are not intended to limit the scope of the patent application of the present invention. All equivalent changes or modifications made under the technical spirit of the present invention should fall within the patent scope covered by the present invention.

Claims

1. A method for installing a fully welded double-layer steel truss arch bridge involving cultural heritage and waterways, characterized in that, The fully welded double-layer steel truss arch bridge includes main bridge piers (10), main beams (20), and two main arches (30) spaced apart along the transverse direction. The main bridge piers (10) include piers P3, P4, P5, and P6. Piers P4, P3, P5, and P6 are located on the two banks of the river, with piers P4 and P5 being closer to their respective riverbanks. The area between pier P4 and its corresponding riverbank, and between pier P5 and its corresponding riverbank, is a protected cultural heritage area (60). The main beams (20) include two side spans (21) on land on both sides of the river and a middle span (23) on the water connecting the two side spans (21). Both the side spans (21) and the middle span (23) include several main beam segments (24) connected in sequence. Each main beam segment (24) includes two main truss segments (25), a node crossbeam (40) connecting the two main truss segments (25), a lower bridge deck system (26), and an upper bridge deck system (27). The main truss segments (25) are erected and fixed on the main bridge piers (10), the lower bridge deck system (26) is erected and fixed at the bottom of the main truss segments (25), and the upper bridge deck system (27) is erected and fixed at the top of the main truss segments (25). Both main arches (30) are erected and fixed on the main truss segments (25) of the main beam (20), and the two main arches (30) are fixedly connected by cross bracing (35). The main arches (30) and the main truss segments (25) of the main beam (20) are connected by slings (50). The installation method of the fully welded double-layer steel truss arch bridge includes the following steps: S1, Erect temporary piers on the shore (81) and temporary piers in the water (83): Erect temporary piers on the shore (81) between piers P3 and P4 and piers P5 and P6 to form an onshore assembly platform, and erect temporary piers in the water area where the river is located to form a water assembly platform, and simultaneously complete the assembly of the main girder (20) main truss (25), the lower bridge deck system (26) and the upper bridge deck system (27); S2, Install the main beam (20): The main beam (20) is assembled in situ on the shore assembly platform and the water assembly platform. During the installation, the side span (21) above the cultural heritage protection area (60) is assembled first, and the remaining side span (21) is assembled from the cultural heritage protection area (60) towards the direction away from the river. At this time, the crawler crane (100) used for assembly is located on land. Then the middle span (23) in the water area is assembled. The crawler crane (100) is transferred to the assembled upper bridge deck system (27) and assembled from the cultural heritage protection area (60) towards the middle of the bridge until the bridge is closed. The installation sequence of the main beam segments (24) of the side span (21) and the middle span (23) is the main truss segment (25) → lower bridge deck system (26) → upper bridge deck system (27). S3, Installation of main arch support (90): After the main beam (20) is installed, the crawler crane (100) is used to install the main arch support (90) on the assembled upper bridge deck system (27). The main arch support (90) is used to temporarily support the main arch (30) during the installation of the main arch (30). S4, main arch (30) assembly: During the construction of the main beam (20), several main arch segments that constitute the main arch (30) are assembled simultaneously; S5, Main arch (30) installation: Two crawler cranes (100) are used to hoist the main arch segments of the main arch (30) from both sides of the bridge to the middle on the assembled upper bridge deck system (27) until the bridge is closed. During the installation of the main arch (30), the cross bracing (35) connecting the two main arches (30) is installed simultaneously. S6, temporary structure removal and construction completed: After the main arch (30) is installed, the entire bridge is installed and the temporary structure is removed. First, the main arch support (90) is removed, the tensioning cable (50) is tensioned, and then the temporary pier in the water (83) and the temporary pier on the shore (81) are removed.

2. The installation method of a fully welded double-layer steel truss arch bridge involving cultural relics and waterways as described in claim 1, characterized in that, In step S2, the lower bridge deck system (26) and the upper bridge deck system (27) are both assembled by welding several bridge deck units (28) in sequence. Each bridge deck unit (28) includes a bridge deck (281), several main crossbeams (282) spaced apart, and several secondary crossbeams (283) spaced apart. The main crossbeams (282) and the secondary crossbeams (283) are welded to the bottom surface of the bridge deck (281). The main crossbeams (282) and the secondary crossbeams (283) extend along the transverse direction of the bridge. Several secondary crossbeams (283) are provided between two adjacent main crossbeams (282). The width of each bridge deck unit (28) is 2m to 3.9m.

3. The installation method of a fully welded double-layer steel truss arch bridge involving cultural relics and waterways as described in claim 2, characterized in that, The installation method of the lower bridge deck system (26) and the upper bridge deck system (27) in step S2 is as follows: For the installation of the bridge deck unit (28) above the river and the cultural relics protection area (60), before hoisting, the bridge deck (281) of several bridge deck units (28) is widened to obtain a plate with a width of 15±2 meters. Then, the secondary crossbeams (283) of several bridge deck units (28) are welded onto the plate to form an ultra-wide flexible bridge deck hoisting assembly. During installation, the main crossbeams (282) of several bridge deck units (28) are hoisted to the preset installation position of the main truss plate (25) by the crawler crane (100) for welding and installation. Then, the bridge deck hoisting assembly is hoisted to the preset installation position and connected to the main crossbeam (282) by the crawler crane (100).

4. The installation method of a fully welded double-layer steel truss arch bridge involving cultural relics and waterways as described in claim 1, characterized in that, The main truss section (25) includes an upper chord (251), a lower chord (252), a node plate (253), and several web members (254). The upper chord (251) and the lower chord (252) are arranged vertically at intervals. The inner surfaces of the upper chord (251) and the lower chord (252) are both welded and fixed with node plates (253) that are connected to the web members (254). The several web members (254) are arranged along the main truss section (251). The lengths of the members are arranged sequentially, and the two ends of each member (254) are welded and fixed to the node plate (253) of the upper chord (251) and the node plate (253) of the lower chord (252), respectively. The length of the lower chord (252) of the main truss (25) above the cultural heritage protection area (60) reaches 30m, and the length of the lower chord (252) of the main truss (25) above the water navigation area (70) reaches 40m.

5. The installation method of a fully welded double-layer steel truss arch bridge involving cultural relics and waterways as described in claim 4, characterized in that, For the main truss segment (25) above the cultural heritage protection area (60), its lower chord (252) is provided with three node plates (253) spaced apart along its length direction; for the main truss segment (25) above the navigable area (70) in the water, its upper chord (251) is provided with four node plates (253) spaced apart along its length direction.

6. The installation method of a fully welded double-layer steel truss arch bridge involving cultural relics and waterways as described in claim 4, characterized in that, In step S2, the main truss section (24) above the navigable area (70) in the water is hoisted in a disassembled state; the main truss section (24) above the cultural heritage protection area (60) is hoisted in a half-truss section state; and the main truss section (24) above the cultural heritage protection area (60) and the non-navigable area (70) is hoisted in a truss section state.

7. The installation method of a fully welded double-layer steel truss arch bridge involving cultural relics and waterways as described in claim 6, characterized in that, When the main truss segment (24) is hoisted in a disassembled state, the crawler crane (100) is used to hoist the upper chord (251), lower chord (252), node plate (253) and web member (254) of the main truss segment (24) to the preset installation position and then welded and assembled.

8. The installation method of a fully welded double-layer steel truss arch bridge involving cultural relics and waterways as described in claim 6, characterized in that, When hoisting the main truss segment (24) in a half-truss state, the upper chord (251) and the corresponding web member (254) are first welded and assembled into at least half-truss structure. Then, the crawler crane (100) is used to hoist the lower chord (252) and the corresponding half-truss structure of the main truss segment (24) to the preset installation position and then welded and assembled.

9. The installation method of a fully welded double-layer steel truss arch bridge involving cultural relics and waterways as described in claim 6, characterized in that, When hoisting the main truss segment (24) in the form of truss segments, the upper chord (251), web members (254) and lower chord (252) are first welded and assembled into the main truss segment (24). Then, the crawler crane (100) is used to hoist the main truss segment (24) as a whole to the preset installation position and then welded and assembled with other main truss segments (24).

10. The installation method of a fully welded double-layer steel truss arch bridge involving cultural relics and waterways as described in claim 1, characterized in that, In step S2, for the installation of the side span (21), the crawler crane (100) is positioned on the ground and one of the main beam segments (24) is installed as the reference segment, starting from the bridge piers P4 and P5. Then, starting from the reference segment, the corresponding side span (21) part above the cultural heritage protection area is assembled. The remaining main beam segments (24) of the side span (21) are installed from the reference segment toward the bridge piers P3 or P6.

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