Construction method for a single-pylon single-cable-plane cable-stayed bridge with a steel box girder

Abstract

The present invention discloses a construction method for a steel box girder single-pylon single-cable-plane cable-stayed bridge, which comprises the following steps: Step 1: Pouring of the cast-in-place concrete box girder segment; Step 2: Installation of the cable crane; Step 3: Installation of the main pylon and the cable-stayed cable layout device; Step 4: Hoisting of the steel box girder segment and layout of the cable-stayed cables; Step 5: Construction of the counterweight for the side span and the main span; Step 6: Removal of the hoisting equipment; In the said Step 4, the steel box girder segment is hoisted in sections and the cable-stayed cables are laid out. The steel box girder segment is split into several beam segments and hoisted one by one and the corresponding cable-stayed cables are laid out. Compared with the construction method of the traditional steel box girder cable-stayed bridge, the method of using a cable crane to replace a truck crane, a crawler crane and a full hall scaffold can effectively reduce the safety hazards in the construction of the steel box girder segment and improve the installation accuracy, and the combination of the cast-in-place concrete box girder and the steel box girder can effectively reduce the construction cost.

Description

Technical Field

[0001] The present invention relates to the technical field of bridge engineering, and particularly relates to a construction method for a steel box girder single pylon single cable plane cable-stayed bridge. Background Art

[0002] As a classic bridge type suitable for various spans, cable-stayed bridges have achieved great success in bridge construction in China. Cable-stayed bridges in China are spread all over the country. Among these bridges, there are small cable-stayed bridges with a span of less than 50m and large-span cable-stayed bridges with a span of more than 500m; there are various tower shapes such as single pylon, double pylons, multi-pylons, and inclined towers; there are beam types made of various materials such as concrete beams, steel beams, composite beams, and hybrid beams. However, in the construction of existing steel box girder single pylon single cable plane cable-stayed bridges, the construction of steel box girders often adopts methods such as truck cranes, crawler cranes, and full hall scaffolds. There are relatively large safety hazards, low installation accuracy, and often high construction costs. Therefore, the inventor proposed a construction method in daily construction that can effectively reduce safety hazards, improve installation accuracy, and reduce construction costs. Summary of the Invention

[0003] The purpose of the present invention is to provide a construction method for a steel box girder single pylon single cable plane cable-stayed bridge. Using a cable crane to replace truck cranes, crawler cranes, and full hall scaffolds can effectively reduce the safety hazards in the construction of steel box girder main beam segments and improve the installation accuracy. Moreover, the combination of cast-in-situ concrete box girders and steel box girders can effectively reduce construction costs.

[0004] The present invention is achieved through the following technical solutions:

[0005] A construction method for a steel box girder single pylon single cable plane cable-stayed bridge includes the following steps:

[0006] Step 1: Pouring of cast-in-situ concrete box girder segments;

[0007] Step 2: Installation of the cable crane;

[0008] Step 3: Installation of the main pylon and the cable-stayed cable layout device;

[0009] Step 4: Hoisting of the steel box girder main beam segments and layout of the cable-stayed cables;

[0010] Step 5: Construction of the counterweight for the side span and the main span;

[0011] Step 6: Demolition of the hoisting equipment;

[0012] In the fourth step, the steel box girder segments are hoisted in sections and the stay cables are arranged. The steel box girder segments are split into several segments, and each segment is hoisted and the corresponding stay cables are arranged. To solve the above technical problems and achieve the corresponding technical effects, compared with the construction method of traditional steel box girder cable-stayed bridges, using a cable crane to replace truck cranes, crawler cranes, and full hall scaffolds can effectively reduce the safety hazards in the construction of steel box girder segments and improve the installation accuracy. Moreover, the combination of cast-in-situ concrete box girders and steel box girders can effectively reduce the construction cost.

[0013] Further technical solution:

[0014] The single cable plane cable-stayed bridge includes a cast-in-situ concrete box girder segment, a section of steel box girder segment, a concrete box girder stay cable group, and a steel box girder stay cable group. The cast-in-situ concrete box girder segment is poured from any end of the bridge body towards the middle and is connected to the steel box girder segment, and the steel box girder segment extends to the other end of the bridge body;

[0015] The stay cables include a concrete box girder stay cable group and a steel box girder stay cable group. The concrete box girder stay cable group includes several concrete box girder stay cables, and the steel box girder stay cable group includes several steel box girder stay cables, and one concrete box girder stay cable corresponds to one steel box girder stay cable;

[0016] The lower anchor point of the concrete box girder stay cable is anchored to the cast-in-situ concrete box girder segment, and the upper anchor point of the concrete box girder stay cable is anchored to the stay cable anchor point set on the main cable tower;

[0017] The lower anchor point of the steel box girder stay cable is anchored to the steel box girder segment, and the upper anchor point of the steel box girder stay cable is anchored to the stay cable anchor point set on the main cable tower.

[0018] Further: In the second step, cable towers of the cable crane are set at the connection between the cast-in-situ concrete box girder segment and the steel box girder segment and at the other end of the bridge body, and then the main cable, towing cable, and lifting cable are arranged.

[0019] Further: When arranging the main cable, first use a boat to cross a 20-mm nylon rope across the river, and then use the nylon rope to tow the steel cable across the river. When towing the steel cable across the river, the size of the steel cable needs to be gradually increased, and with the help of the main cable, the towing cable and the lifting cable are finally arranged.

[0020] Further: In the second step, a main cable tower for arranging the stay cables is installed at the crane position of one cable crane. A slewing scaffold is set on the main cable tower, and a winch is set on the slewing scaffold. The towing rope of the winch pulls the stay cable through a pulley block.

[0021] Further: In the fourth step, when hoisting the steel box girder segment, the steel box girder segment is split into a beam segment A close to the main tower, a beam segment D far from the main tower, a beam segment B in the middle, and a beam segment C for final connection and assembly;

[0022] Further: First, hoist the A beam segment. After the A beam segment is hoisted to the installation position near the main cable tower, grout is used to connect the A beam segment to the cast-in-place concrete box girder segment near the main cable tower, and then the corresponding stay cables are arranged.

[0023] Further: After the construction of the A beam segment is completed, hoist the B beam segment. The B beam segment is split into several beam segments and hoisted one by one, and several B beam segments are welded, and then the corresponding stay cables are arranged.

[0024] Further: After the construction of the B beam segment is completed, hoist the D beam segment. After the D beam segment is hoisted to the installation position far from the main cable tower, grout is used to connect the D beam segment to the cast-in-place concrete box girder segment far from the main cable tower, and then the corresponding stay cables are arranged.

[0025] Further: After the construction of the D beam segment is completed, hoist the C beam segment. First, determine the lengths at both ends of C according to the distance between the B beam segment and the D beam segment, and hoist the C beam segment with the determined length between the B beam segment and the D beam segment. Then, weld the beam segments of the C beam segment to the B beam segment and the D beam segment respectively to complete the closure of the whole bridge, and then arrange the corresponding stay cables.

[0026] Further: When constructing the B beam segment, the B beam segment is split into several beam segments with a length of 12 m, and welding is carried out after each beam segment is hoisted in place.

[0027] Further: Before connecting each beam segment, adjust the plane position and elevation of the beam segment by a three-way jack.

[0028] Further: In the fourth step, the specific method for arranging the stay cables is as follows: For the installation of the beam part of the stay cable, when hoisting the lower anchor head to the beam end anchoring position, use the steel strand soft traction cable to pass through the beam end anchor to complete the anchoring of the lower anchor head and the beam segment.

[0029] Further: For the installation of the tower end of the stay cable, first transfer the upper anchor head to the position below the tower end anchoring position, start the winch to lower the traction rope, connect the upper anchor head through the pulley block, and lift the upper anchor head to the tower end anchoring position. Use the steel strand soft traction cable to pass through the tower end anchor to complete the anchoring of the upper anchor head and the main cable tower.

[0030] Further: In the sixth step, after the construction of the side span and the main span deadweight is completed, remove the cable crane and the support for the beam segment, and adjust the stay cable tension and the bridge deck alignment to complete the construction of the whole bridge.

[0031] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0032] 1. A construction method for a steel box girder single-pylon single-cable-plane cable-stayed bridge according to the present invention. Compared with the construction methods of traditional steel box girder cable-stayed bridges, the method of using a cable crane to replace truck cranes, crawler cranes, and full hall scaffolds can effectively reduce the safety hazards in the construction of steel box girder segments and improve the installation accuracy. Moreover, the combination of cast-in-place concrete box girders and steel box girders can effectively reduce the construction cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] To more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative efforts. In the drawings:

[0034] Figure 1 is the construction flow chart of the present invention;

[0035] Figure 2 is the structural schematic diagram of the steel box girder single-pylon single-cable-plane cable-stayed bridge of the present invention;

[0036] Figure 3 is the structural schematic diagram of the main pylon and the cable-stayed cable layout device;

[0037] Figure 4 is the construction schematic diagram of the A girder segment;

[0038] Figure 5 is the construction schematic diagram of the B girder segment;

[0039] Figure 6 is the construction schematic diagram of the D girder segment;

[0040] Figure 7 is the construction schematic diagram of the C girder segment.

[0041] Markings in the drawings and corresponding component names:

[0042] 1 - cast-in-place concrete box girder segment, 2 - cable crane, 3 - main pylon, 4 - steel box girder segment, 5 - concrete box girder cable-stayed cable group, 6 - steel box girder cable-stayed cable group, 31 - slewing scaffold, 32 - winch, 33 - towing rope, 34 - pulley block. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0043] To make the objectives, technical solutions, and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below in combination with the embodiments and the drawings. The illustrative embodiments of the present invention and their descriptions are only used to explain the present invention and are not intended to limit the present invention.

[0044] In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, it will be apparent to one of ordinary skill in the art that: the present invention may be practiced without these specific details. In other instances, well-known structures, circuits, materials, or methods have not been specifically described in order to avoid obscuring aspects of the present invention.

[0045] Throughout the specification, references to "one embodiment", "an embodiment", "an example", or "an example" mean that a particular feature, structure, or characteristic described in connection with the embodiment or example is included in at least one embodiment of the present invention. Thus, the appearances of the phrases "one embodiment", "an embodiment", "an example", or "an example" throughout the specification are not necessarily all referring to the same embodiment or example. Furthermore, the particular features, structures, or characteristics may be combined in any suitable combination and / or sub-combination in one or more embodiments or examples. Additionally, those of ordinary skill in the art will understand that the diagrams provided herein are for illustrative purposes only and are not necessarily drawn to scale. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0046] In the description of the present invention, the orientation or positional relationships indicated by the terms "front", "rear", "left", "right", "up", "down", "vertical", "horizontal", "high", "low", "inner", "outer", etc. are based on the orientation or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as limiting the scope of protection of the present invention.

[0047] Embodiment

[0048] As Figures 1 to 7 shown, a construction method for a steel box girder single-tower single-cable-plane cable-stayed bridge of the present invention includes the following steps:

[0049] Step 1: Pouring of the cast-in-place concrete box girder segment 1;

[0050] Step 2: Installation of the cable crane 2;

[0051] Step 3: Installation of the main cable tower 3 and the cable-stayed cable layout device;

[0052] Step 4: Hoisting of the steel box girder segment 4 and layout of the cable-stayed cables;

[0053] Step 5: Construction of the counterweight for the side span and the main span;

[0054] Step 6: Removal of the hoisting equipment;

[0055] In Step 4, the steel box girder section 4 is hoisted in sections and the stay cables are arranged. The steel box girder section 4 is split into several beam sections and hoisted one by one, and the corresponding stay cables are arranged. In this embodiment, the total length of the cable-stayed bridge is 268 m. The construction is carried out using a single-tower single-cable-plane hybrid girder cable-stayed bridge with a main span of 175 m. The span combination of the bridge body is 81 + 175 m, and the deck width is 32 m. Moreover, the method of using a cable crane 2 to replace the traditional truck crane, crawler crane, and full hall scaffold for hoisting the steel box girder section 4 can effectively reduce the safety hazards in the construction of the steel box girder section and improve the installation accuracy. And the combination of cast-in-place concrete box girder and steel box girder can effectively reduce the construction cost.

[0056] The single-cable-plane cable-stayed bridge includes a cast-in-place concrete box girder section 1, a steel box girder section 4, a concrete box girder stay cable group 5, and a steel box girder stay cable group 6. The cast-in-place concrete box girder section 1 is poured from any end of the bridge body towards the middle and is connected to the steel box girder section 4, and the steel box girder section 4 extends to the other end of the bridge body;

[0057] The stay cables include a concrete box girder stay cable group 5 and a steel box girder stay cable group 6. The concrete box girder stay cable group 5 includes several concrete box girder stay cables. The steel box girder stay cable group 6 includes several steel box girder stay cables, and one concrete box girder stay cable corresponds to one steel box girder stay cable;

[0058] The lower anchor point of the concrete box girder stay cable is anchored to the cast-in-place concrete box girder section 1, and the upper anchor point of the concrete box girder stay cable is anchored to the stay cable anchor point set on the main cable tower 3; the lower anchor point of the steel box girder stay cable is anchored to the steel box girder section 4, and the upper anchor point of the steel box girder stay cable is anchored to the stay cable anchor point set on the main cable tower 3. In this embodiment, the west bank of the bridge body is selected for pouring the cast-in-place concrete box girder section 1, and the length of the cast-in-place concrete box girder section 1 is preferably 81 m, and the main cable tower 3 is installed and fixed on the cast-in-place concrete box girder section 1, which can effectively ensure the stability of the main cable tower 3, thereby ensuring the stability of the entire bridge body, and using the concrete box girder stay cable group 5 to balance the tension of the steel box girder stay cable group 6, thereby avoiding the occurrence of dangers such as the overturning of the main cable tower 3.

[0059] In Step 2, cable towers of the cable crane 2 are arranged at the connection between the cast-in-place concrete box girder section 1 and the steel box girder section 4 and at the other end of the bridge body, and then the main cable, towing cable, and hoisting cable are arranged.

[0060] When laying the main cable, first use a boat to cross a 20-mm nylon rope across the river, and then use the nylon rope to tow the steel cable across the river. When towing the steel cable across the river, the size of the steel cable should be gradually increased, and finally, with the help of the main cable, the towing cable and the hoisting cable are laid. In this embodiment, the overall layout of the cable crane 2 is as follows: the span of the main cable of the cable crane is arranged as 89 m (western side span) + 242 m + 50 m (eastern side span), with each span arranged continuously. The intermediate transfer point is supported on the saddle of the tower, and both ends are fixed on the anchor device. The vertical distance between the top of the saddle on the west bank and the anchor is 27 m, and the vertical distance between the top of the saddle on the east bank and the anchor is 21.5 m. The maximum sag-span ratio of the main cable during construction is fmax / L = 1 / 14. The main cable is divided into 2 groups, and each group is composed of (8X36SW+IWR) steel core wire ropes. The center distance between the two groups of main cables is 13 m. One trolley is installed on each group of main cables, and the designed lifting weight of each lifting point is 100 t. The cable crane can bear a lifting weight of 200 t. The towing cable is wound in a "4" pattern with a Ф26 steel wire rope. Two 10-t towing winches are arranged in front of each anchor on both banks, and there are 4 winches in total for the whole bridge. The hoisting cable is wound in an "8" pattern with a Ф32 steel wire rope, and the two ends are respectively wound on the drums of the 15-t hoisting winches on both banks. One trolley corresponds to a set of hoisting equipment. The hoisting and towing of two trolleys with similar transverse positions on two groups of main cables of the same model must be synchronized. The saddle is selected in the form of a double-row rolling pulley. One row of pulleys on the side close to the ground anchor is lower to reduce the bending stress of the main cable. The number of pulleys of the saddle in the transverse direction is determined by the number of main cables. Two separate pulleys can be arranged on the upper part of the saddle for passing the towing cable. A hoisting cable pulley is arranged under the main cable pulley; in this way, the towing cable and the hoisting cable can be clearly separated, which is beneficial to hoisting. The cable tower is assembled with a combined steel pipe truss, and its plane is 4 m × 4 m. The height of the cable tower on the west bank is 27 m, and the height of the cable tower on the east bank is 32.7 m. The transverse connection of the two limbs of the cable tower on the west bank is set outside the tower column and crosses the main tower of the cable-stayed bridge, with a distance of 30 cm from the main tower to ensure that there is no contact with the main tower when the cable tower deflects; the middle and top of the bottom of the cable tower on the east bank adopt a 4 m × 4 m structural tie beam. The foundation of the main tower on the west bank is set on the box girder, and the main tower on the east bank adopts a short-pile cap foundation. Anchor: The west bank anchor is located behind the side-span abutment and adopts two gravity anchors and pile-composite anchors, respectively, with guy cables. The east bank anchor is located at the foot of the mountain and adopts two rock anchors. The ground anchors for the tower guy cables and the transverse guy cables during hoisting generally bear little force and are buried by digging pits and laying bedrocks.

[0061] Among them, the cable tower consists of several parts such as the base, tower body, tower top and cable saddles. The base is made of C25 concrete. When pouring the concrete, steel plates connected to the tower body should be embedded, and the anchor bars should be welded well. The concrete must be dense. The connection between the base and the tower body uses pin joints with special pins for the 64th Army beams. The tower body is assembled section by section. That is, on the basis of the assembled tower body foundation, a single-legged gin pole is set up, and the truss sections are lifted by the gin pole for assembly. During assembly, it should be noted that the two side towers are assembled simultaneously. When installed to a certain height, wind braces should be set horizontally and temporary anti-wind cable stays should be set longitudinally. Permanent anti-wind cable stays are set after complete installation. The tower top is longitudinally welded with 2 I-beams of No. 56 side by side. A 2-cm steel plate is welded at the bottom of the I-beams and connected to the tower body with pins. 2 I-beams of No. 56 are erected on top of the two longitudinal I-beams. The longitudinal and transverse I-beams should be welded firmly and full welding should be carried out to ensure that the cross beam will not turn over. To ensure that the main cable passes smoothly through the cable saddle, the top of the cable saddle is made into a semi-circular arc with a radius of 30 cm. 13 steel rollers that can roll freely are placed at the bottom. The bottom plate should be welded firmly to the cross beam, and the bottom plate is connected to the cable saddle in a reverse buckling form, leaving a 15-mm free rolling space on each side. In this way, under the influence of the suspended load and temperature, the cable saddle has a displacement of 30 mm, reducing the frictional loss between the cable saddle and the main cable. steel rollers, and the bottom plate should be welded firmly to the cross beam. The bottom plate is connected to the cable saddle in a reverse buckling form, leaving a 15-mm free rolling space on each side.

[0062] Installation of the main cable: Since there is no navigation on both sides of the river, first use a boat to cross a 2-cm nylon rope across the river, and use the nylon rope to carry a 15-mm steel wire rope. In this way, it needs to be replaced step by step, and finally the main cable is pulled across the river. When pulling the main cable across the river, in order to reduce the stress on the winch, a certain sag must be ensured. To make the main cable as evenly stressed as possible during use, the two main cables are tied together and wound around the ground anchor twice. The main cable can be adjusted according to the sag and stress conditions. The installation sag of the main cable should conform to the design value. If it is less than or much less than the design value, important components such as the main cable, ground anchor, and cable tower will be overloaded or severely overloaded, which is very dangerous. On the contrary, if the installation sag of the cable is greater than the design value, the working sag will increase, thereby increasing the up and down slope when lifting components, and increasing the traction force. If the increase value is too large, auxiliary traction needs to be set up. Even if it still cannot meet the safety height for crossing the already installed bridge span structure, it will increase the installation workload of the components, resulting in installation difficulties. Before installing the main cable, the control stress and initial sag during installation must be calculated.

[0063] Installation of the hoisting cable: The pulley (block) group uses 3 upper wheels and 2 lower wheels to form a 4-line pulley block. To avoid entanglement, the 2 lower wheels use a split wheel group. The hoisting cable uses a steel wire rope, one end of the hoisting cable is fixed on the winch, and the other end passes around the hook and is fixed on the trolley. The length of the hoisting cable should be ensured so that when lifting the farthest point, there are at least 6 turns of the steel wire rope on the winch.

[0064] Installation of the towing cable: The towing cable uses The steel wire rope is towed in a series of rolling manner. One end of the towing cable is fixed on the trolley, then it bypasses the main cable on the opposite bank of the river and the fixed pulley on the anchor block, and then bypasses the main tower and the fixed pulley on this bank. To increase the friction between the towing cable and the winch, the steel wire rope is wound around the winch for 6 turns, and finally it bypasses the fixed pulley on the main tower and is still fixed on the trolley.

[0065] Installation of the main cable trolley and the lifting hook: The main cable trolley uses a self-made trolley with 2 doors. The diameter of the sliding wheel in contact with the main cable is 25 cm, and the diameter of the fixed pulley is 34 cm.

[0066] In the second step, a main cable tower 3 for laying the stay cables is installed at the crane position of one cable crane 2. A revolving scaffold 31 is arranged on the main cable tower 3, and a winch 32 is arranged on the revolving scaffold 31. The towing rope 33 of the winch 32 is tied to the stay cable through the pulley block 34. In this embodiment, after the installation of the main cable tower 3 is completed, the revolving scaffold 31 is assembled on the top of the main cable tower 3 with universal members. To meet the needs of installing stay cables in different directions at the tower part, a slewing bearing is configured between the revolving scaffold 31 and the top of the main cable tower 3 to realize the 360° rotation of the revolving scaffold 31. The revolving scaffold 31 can be pulled in the corresponding direction by a chain block to realize rotation. The revolving scaffold 31, winch 32, towing rope 33 and pulley block 34 on the top of the tower are equivalent to a small tower crane installed on the top of the tower and are the main lifting equipment when hanging the stay cables at the tower part.

[0067] In the fourth step, when hoisting the steel box girder segment 4, the steel box girder segment 4 is split into an A girder segment close to the main tower, a D girder segment far from the main tower, an intermediate B girder segment and a C girder segment for final connection and assembly;

[0068] First, hoist the A girder segment. After the A girder segment is hoisted to the installation position close to the main cable tower 3, grout is used to connect the A girder segment with the cast-in-situ concrete box girder segment 1 close to the main cable tower 3, and then the corresponding stay cables are arranged;

[0069] After the construction of the A girder segment is completed, hoist the B girder segment. The B girder segment is split into several girder segments and hoisted one by one, and several B girder segments are welded, and then the corresponding stay cables are arranged;

[0070] After the construction of the B girder segment is completed, hoist the D girder segment. After the D girder segment is hoisted to the installation position far from the main cable tower 3, grout is used to connect the D girder segment with the cast-in-situ concrete box girder segment 1 far from the main cable tower 3, and then the corresponding stay cables are arranged;

[0071] After the construction of the D beam segment, the hoisting of the C beam segment is carried out. First, determine the lengths at both ends of C according to the distance between the B beam segment and the D beam segment, and hoist the C beam segment with the determined length between the B beam segment and the D beam segment. Then, weld the beam segments of C to the B beam segment and the D beam segment respectively to complete the closure of the whole bridge, and then lay the corresponding stay cables. In this embodiment, when constructing all box girder segments, first determine a relatively large hoisting site near the construction site, hoist the segmental steel box girder to the installation area with a cable crane, weld positioning code plates at the interfaces of the already installed segments to position the relative positions of the box girder segments, and connect temporary bolts. Use a chain block to adjust the relative position of the box girder at the interface, and operate the cable crane to adjust the absolute position of the box girder on the whole bridge. After the total station monitors and adjusts the box girder to the correct spatial position, tighten the connecting bolts and position weld. The cable crane does not release the hook before the welding of the box girder installation interface and the pre-tensioning of the stay cable hanging. Under the specific construction method of the steel box main girder segment 4, four-point hoisting is adopted for the hoisting of each box girder segment. Before hoisting, it should be noted that large-volume equipment such as dehumidifiers permanently placed in the box should be pre-placed in the corresponding beam segment positions before hoisting. After the beam segment is hoisted in place, make a temporary connection with the adjacent beam segment, use a dowel pin to adjust the misalignment of the plate members, and tighten the temporary connection tie rods to the design joint width and then fix them. First, weld the transverse circumferential seams of the peripheral plates, and after passing the non-destructive testing, weld the longitudinal stiffener patch segments. After passing the inspection, perform necessary grinding treatment on the welds to complete the connection of the beam segments. To facilitate manual handling and stacking, the counterweight material uses heavy concrete blocks, and the material specific gravity is not less than 36 KN / m 3 . The counterweight blocks should be evenly placed transversely in the steel box girder. First, set steel profiles in the transverse direction of the bottom plate U-ribs, then set steel backing plates with a thickness of 6 mm on them, and weld and fix them to the steel profiles. A retaining structure should be set around the steel backing plates, and then place the counterweight blocks stably and reliably on the steel backing plates. Note that the counterweight should consider the weight of the steel backing plates and the steel profiles below them. The position of the stacked blocks can be adjusted transversely appropriately near the manhole to facilitate the passage of people.

[0072] When constructing the B beam segment, the B beam segment is split into several beam segments with a length of 12 m, and each beam segment is welded after being hoisted in place. In this embodiment, the B beam segment is split into 12 small beam segments (B1 - B12). When hoisting, temporary ballasting should be carried out on the main span B1 - B10 beam segments. The temporary ballasting load is 72.9 KN / m along the longitudinal bridge direction to reduce the bending moment of the main girder near the cable tower during the construction process. The temporary ballasting takes a 12-m long beam segment as a loading unit, and the time of temporary ballasting lags behind the hoisting of the main span beam segments by two beam segments. The removal of the temporary ballasting must be carried out synchronously with the construction of the deck system to ensure that the load borne by the main girder does not change too much.

[0073] Before connecting each beam segment, the plane position and elevation of the beam segment are adjusted by a three-way jack. In this embodiment, the elevation of the end of each box girder segment during construction must be determined before sunrise. After the elevation of the beam end is determined, the temporary matching parts shall be quickly connected, and then the joint welding work shall be carried out. In principle, it is required that all welds pass the quality inspection before the stay cables are tensioned for the first time. After the tensioning is in place, the crane can be released and moved forward.

[0074] In the fourth step described above, the layout method of the stay cables is as follows: For the installation of the stay cables at the beam part, when the lower anchor head is hoisted to the beam end anchoring position, a steel strand soft towing cable is used to pass through the beam end anchor to complete the anchoring of the lower anchor head and the beam segment; for the installation of the stay cables at the tower end, first transfer the upper anchor head to the position below the tower end anchoring position, start the winch 32 to release the towing rope 33, connect the upper anchor head through the pulley block 34, and lift the upper anchor head to the tower end anchoring position. A steel strand soft towing cable is used to pass through the tower end anchor to complete the anchoring of the upper anchor head and the main cable tower 3. In this embodiment, the beam end anchoring is carried out first, and then the traction and tensioning anchoring are carried out inside the tower. When the stay cables arrive at the bridge site, the tower crane is used to directly lift the stay cables onto the bridge deck and place them on the horizontal cable laying reel; the winch on the bridge deck pulls the beam end anchor head to the cantilever end of the beam segment to be installed, and then a 25t truck crane is used to hoist the lower anchor head of the stay cable to the beam end anchoring point for anchoring; the pulley block 34 lifts the upper anchor head of the stay cable with the assistance of the winch at the root of the main cable tower 3 to assist in the deployment on the bridge deck, and the winch 32 at the top of the main cable tower 3 is used to hoist the upper anchor head to the tower end anchoring point for anchoring; finally, the tensioning and tower end cable adjustment are carried out at the tower end.

[0075] In the sixth step described above, after the counterweight construction of the side span and the main span is completed, the cable crane 2 and the brackets for supporting the beam segments are removed, and the tension of the stay cables and the bridge deck line are adjusted to complete the construction of the whole bridge. In this embodiment, in order to make the stay cables adapt to the self-weights of the cast-in-place concrete box girder segment 1 and the steel box girder segment 4 of the side span, counterweights need to be carried out on the side span and the main span before the brackets of the side span and the D beam segment are removed. After the counterweight is completed, the two brackets are removed.

[0076] The specific embodiments described above further elaborate on the purpose, technical solutions, and beneficial effects of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not used to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A construction method for a single-pylon single-cable-plane cable-stayed bridge with a steel box girder, characterized in that, It includes the following steps: Step 1: Pouring of the cast-in-place concrete box girder section (1); Step 2: Installation of the cable crane (2); Step 3: Installation of the main cable tower (3) and the cable-stayed cable layout device; Step 4: Hoisting of the steel box girder section (4) and layout of the cable-stayed cables; Step 5: Construction of the counterweight for the side span and the main span; Step 6: Removal of the hoisting equipment; In the said Step 4, the steel box girder section (4) is hoisted in sections and the cable-stayed cables are laid out. The steel box girder section (4) is split into several beam sections and hoisted one by one and the corresponding cable-stayed cables are laid out; In the said Step 4, when hoisting the steel box girder section (4), the steel box girder section (4) is split into the A beam section close to the main tower, the D beam section far from the main tower, the B beam section in the middle and the C beam section for final connection and assembly; First, hoist the A beam section. After the A beam section is hoisted to the installation position close to the main cable tower (3), grout is used to connect the A beam section with the cast-in-place concrete box girder section (1) close to the main cable tower (3), and then the corresponding cable-stayed cables are laid out; After the construction of the A beam section is completed, hoist the B beam section. And the B beam section is split into several beam sections and hoisted one by one, and several B beam sections are welded, and then the corresponding cable-stayed cables are laid out; After the construction of the B beam section is completed, hoist the D beam section. When the D beam section is hoisted to the installation position far from the main cable tower (3), grout is used to connect the D beam section with the cast-in-place concrete box girder section (1) far from the main cable tower (3), and then the corresponding cable-stayed cables are laid out; After the construction of the D beam section is completed, hoist the C beam section. First, determine the lengths at both ends of C according to the distance between the B beam section and the D beam section, and hoist the determined-length C beam section between the B beam section and the D beam section, and then weld the beam sections of the C beam section to the B beam section and the D beam section respectively to complete the closure of the whole bridge, and then lay out the corresponding cable-stayed cables; The single-plane cable-stayed bridge includes a cast-in-place concrete box girder section (1), a section of steel box girder section (4), a concrete box girder cable-stayed cable group (5) and a steel box girder cable-stayed cable group (6). The cast-in-place concrete box girder section (1) is poured from any one end of the bridge body towards the middle and is connected to the steel box girder section (4), and the steel box girder section (4) extends to the other end of the bridge body; The cable-stayed cables include a concrete box girder cable-stayed cable group (5) and a steel box girder cable-stayed cable group (6). The concrete box girder cable-stayed cable group (5) includes several concrete box girder cable-stayed cables. The steel box girder cable-stayed cable group (6) includes several steel box girder cable-stayed cables, and one concrete box girder cable-stayed cable corresponds to one steel box girder cable-stayed cable; The lower anchor point of the concrete box girder cable-stayed cable is anchored to the cast-in-place concrete box girder section (1), and the upper anchor point of the concrete box girder cable-stayed cable is anchored to the cable anchor point set on the main cable tower (3); The lower anchor point of the steel box girder cable-stayed cable is anchored to the steel box girder section (4), and the upper anchor point of the steel box girder cable-stayed cable is anchored to the cable anchor point set on the main cable tower (3); In the said Step 2, cable towers of the cable crane (2) are arranged at the connection between the cast-in-place concrete box girder section (1) and the steel box girder section (4) and at the other end of the bridge body, and then the main cable, the towing cable and the hoisting cable are laid out.

2. The construction method of a steel box girder single pylon single cable plane cable-stayed bridge according to claim 1, characterized in that, When laying the main cable, first use a boat to carry a 20mm nylon rope across the river, and then use the nylon rope to pull the steel cable across the river. When pulling the steel cable across the river, the size of the steel cable needs to be gradually increased, and the main cable is used to finally complete the laying of the traction cable and the lifting cable.

3. A construction method for a steel box girder single-tower single-cable-plane cable-stayed bridge according to claim 1, characterized in that, In the second step, a main cable tower (3) for laying the inclined cable is installed at a crane position of a cable crane (2), a revolving scaffold (31) is provided on the main cable tower (3), and a winch (32) is provided on the revolving scaffold (31), and a traction rope (33) of the winch (32) is tied to the inclined cable through a pulley group (34).

4. A construction method for a single-pylon single-cable-plane cable-stayed bridge with a steel box girder, characterized in that, When constructing the B beam section, the B beam section is divided into several beam sections with a length of 12 m, and each beam section is welded after being hoisted into place.

5. A construction method for a steel box girder single-pylon single-cable-plane cable-stayed bridge according to claim 1, characterized in that, Before connecting each beam section, the plane position and elevation of the beam section are adjusted by three-way jacks.

6. The construction method of a steel box girder single-pylon single-cable-plane cable-stayed bridge according to claim 3, characterized in that, In the step 4, the method for laying the inclined cable is as follows: when the beam portion of the inclined cable is installed and the lower anchor head is hoisted to the anchor position at the beam end, the steel strand soft traction rope is passed through the beam end anchor to complete the anchoring of the lower anchor head and the beam section; The installation of the tower end of the inclined cable is firstly to transfer the upper anchor head to the lower part of the tower end anchorage position, start the winch (32) to lower the traction rope (33), connect the upper anchor head through the pulley group (34), and lift the upper anchor head to the tower end anchorage position, and use the steel strand soft traction rope to pass through the tower end anchor to complete the anchorage of the upper anchor head and the main cable tower (3).

7. A construction method for a steel box girder single-pylon single-cable-plane cable-stayed bridge according to claim 1, characterized in that, In the step 6, after the side span and main span weight construction is completed, the cable hanger (2) and the bracket for supporting the beam section are removed, and the tension of the inclined cable and the bridge deck line are adjusted to complete the construction of the entire bridge.

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