CN114541286B - Sectional block dismantling construction method for cast-in-situ prestressed box girder - Google Patents
Sectional block dismantling construction method for cast-in-situ prestressed box girder Download PDFInfo
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- E—FIXED CONSTRUCTIONS
- E01—CONSTRUCTION OF ROADS, RAILWAYS, OR BRIDGES
- E01D—CONSTRUCTION OF BRIDGES, ELEVATED ROADWAYS OR VIADUCTS; ASSEMBLY OF BRIDGES
- E01D22/00—Methods or apparatus for repairing or strengthening existing bridges ; Methods or apparatus for dismantling bridges
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- E—FIXED CONSTRUCTIONS
- E01—CONSTRUCTION OF ROADS, RAILWAYS, OR BRIDGES
- E01D—CONSTRUCTION OF BRIDGES, ELEVATED ROADWAYS OR VIADUCTS; ASSEMBLY OF BRIDGES
- E01D2/00—Bridges characterised by the cross-section of their bearing spanning structure
- E01D2/04—Bridges characterised by the cross-section of their bearing spanning structure of the box-girder type
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F30/00—Computer-aided design [CAD]
- G06F30/10—Geometric CAD
- G06F30/13—Architectural design, e.g. computer-aided architectural design [CAAD] related to design of buildings, bridges, landscapes, production plants or roads
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- E—FIXED CONSTRUCTIONS
- E01—CONSTRUCTION OF ROADS, RAILWAYS, OR BRIDGES
- E01D—CONSTRUCTION OF BRIDGES, ELEVATED ROADWAYS OR VIADUCTS; ASSEMBLY OF BRIDGES
- E01D2101/00—Material constitution of bridges
- E01D2101/20—Concrete, stone or stone-like material
- E01D2101/24—Concrete
- E01D2101/26—Concrete reinforced
- E01D2101/28—Concrete reinforced prestressed
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- G06F2119/00—Details relating to the type or aim of the analysis or the optimisation
- G06F2119/14—Force analysis or force optimisation, e.g. static or dynamic forces
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
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Abstract
The invention discloses a sectional block dismantling construction method of a cast-in-situ prestressed box girder, which comprises the steps of firstly constructing a proper temporary support structure and selecting a proper type of hoisting equipment based on the structural characteristics of the cast-in-situ prestressed box girder and the technical consideration of sectional block dismantling of the cast-in-situ prestressed box girder; and then, under the premise of comprehensively considering the bearing capacity of the temporary support structure and the hoisting capacity of hoisting equipment, a section-by-section block-by-block cutting and transferring scheme of the forward bridge direction section and the transverse bridge direction section is constructed aiming at the box chamber part of the cast-in-situ prestressed box girder. Therefore, the invention combines the bridge cutting technology and the bridge structure, utilizes the characteristics of the bridge structure, is matched with a simpler temporary support structure, removes the cast-in-situ prestressed box girder block by block and segment by segment along the longitudinal bridge direction segmentation and transverse bridge direction segmentation modes of the cast-in-situ prestressed box girder, effectively reduces the lifting capacity requirement of lifting equipment, reduces the construction difficulty of erecting/dismantling the temporary support structure, shortens the construction period and ensures the construction safety.
Description
Technical Field
The invention relates to a construction method for dismantling a cast-in-situ box girder, in particular to a construction method for dismantling a cast-in-situ prestressed box girder at a position with a higher bridge height.
Background
Aiming at the demolition construction of the beam bridge, along with continuous progress of technology and massive advocates of civilized and environment-friendly construction, various demolition projects are constructed by adopting more humanized demolition construction methods and technologies.
Bridge dismantling methods include blasting methods and non-blasting methods (such as direct blasting methods, mechanical hoisting methods and the like). Generally, blasting methods have limitations in bridge dismantling construction, and need to be explored for factors such as different bridge types and surrounding environments. The non-blasting method can take the characteristics of bridge dismantling per se into consideration, is safe and reliable, but has more unpredictable factors in the dismantling process, so that the comparison and optimization of the dismantling scheme in the aspects of safety, stability, technical possibility and the like of the dismantling engineering are indispensable work before bridge dismantling; when a non-blasting dismantling method is adopted for a bridge with serious diseases, considering the factors of bearing capacity reduction and uncertainty of the bridge, and ensuring that various indexes are in an allowable range in the bridge dismantling process is a key whether the bridge can be dismantled safely except for strict control on construction organization management. Mechanical removal is generally used across existing vehicular route bridges. The mechanical dismantling method refers to dismantling the bridge in the forms of crushing, dividing, lifting and the like by using mechanical equipment. The underwater bridge is usually removed by adopting a floating crane, and the land support method is usually removed by adopting a large-tonnage crane block. Therefore, on the premise of safely dismantling construction, how to reduce the hoisting capacity of the crane and simplify the temporary support structure is an effective method for shortening the construction period by adopting a mechanical dismantling method for the current bridge.
In addition, for cast-in-situ box girder dismantling, a direct breaking mode is generally adopted, or a full framing is erected under the cast-in-situ box girder, then the cast-in-situ box Liang Yanshun bridge is cut and hoisted to sections and box chambers in a segmented mode, the dismantling support is dismantled in the mode, the investment amount of the dismantling support is large, the tonnage of the used crane is large, the cost control is not facilitated, and meanwhile, the dismantling process is influenced. Meanwhile, for dismantling a cast-in-situ box girder bridge section which spans a river or a cast-in-situ box girder bridge section with insufficient crane station space at two sides, the method for dismantling the box girder by setting up a full framing under the cast-in-situ box girder is not applicable.
Disclosure of Invention
The invention provides a sectional block dismantling construction method for a cast-in-situ prestressed box girder, which aims at the defects of the prior art, combines a bridge cutting technology with a bridge structure, utilizes the characteristics of the bridge structure, is matched with a simpler temporary support structure, and is dismantled block by block and segment by segment in a longitudinal bridge sectional and transverse bridge sectional mode of the cast-in-situ prestressed box girder, thereby effectively reducing the lifting capacity requirement of lifting equipment, reducing the construction difficulty of erecting/dismantling the temporary support structure, shortening the construction period and ensuring the construction safety.
In order to achieve the technical purpose, the invention adopts the following technical scheme:
the construction method for removing the cast-in-situ prestressed box girder in a segmented and block mode comprises the steps of firstly constructing a proper temporary support structure and selecting a proper type of lifting equipment based on the structural characteristics of the cast-in-situ prestressed box girder and technical considerations of removing the cast-in-situ prestressed box girder in a segmented and block mode; then, under the premise of comprehensively considering the bearing capacity of the temporary support structure and the hoisting capacity of hoisting equipment, a section-by-section block-by-block cutting and transferring scheme of the bridge-oriented section and the transverse bridge-oriented section is constructed aiming at the box chamber part of the cast-in-situ prestressed box girder;
the section-by-section block-by-block cutting and transferring scheme comprises a forward bridge-to-section cutting and transferring scheme and a transverse bridge-to-block cutting and transferring scheme which are alternately performed; the bridge-wise piecewise cutting scheme is used for symmetrically and sectionally cutting the box chamber part of the cast-in-situ prestressed box girder in a mode from the center to the two sides along the cast-in-situ prestressed box Liang Shunqiao so as to obtain a transverse bridge-wise through long box chamber section at a corresponding cutting position; the transverse bridge is cut to block by block to the transverse bridge to lead to long case room section that the scheme of transferring is cut to along bridge to the scheme of cutting to block, and with the transverse bridge to the central line of leading to long case room section as the standard, according to roof, outside half package case room piece, central web regional piece's order symmetry demolish transverse bridge to leading to long case room section, just the roof directly demolish through the rupture method, outside half package case room piece, central web regional piece then cut to transfer through hoisting equipment cooperation rope saw cutting method.
As the preferable scheme of the sectional block dismantling construction method, the temporary support structure comprises a plurality of temporary support structures, and each temporary support structure is arranged below the cast-in-situ prestressed box girder and is arranged along the transverse bridge direction of the cast-in-situ prestressed box girder;
the temporary support structure be double steel pipe support structure, including bar basis, vertical pillar and horizontal support, wherein:
the vertical support comprises a middle vertical support and a first side vertical support and a second side vertical support which are symmetrically distributed on two sides of the middle vertical support; the vertical struts are connected through connecting brackets;
the bottom plate of the cast-in-situ prestressed box girder is positioned at the middle position of the transverse bridge direction and is supported by the middle vertical support column; the two ends of the bottom plate of the cast-in-situ prestressed box girder in the transverse bridge direction are supported by two groups of first side vertical struts; the outer end part of the box chamber of the cast-in-situ prestressed box girder is supported by two groups of second side vertical struts;
after the box chambers of the cast-in-situ prestressed box girder are cut by a sequential bridge-to-section cutting scheme, the divided transverse bridge applies a temporary support structure load to the through long box chamber section, and the temporary support structure loads uniformly act on the middle vertical support and the first side vertical support positioned at two sides of the middle vertical support;
The modeling platform is used for accounting, the maximum stress generated by the temporary support structure under the action of uniformly distributed load is smaller than the maximum design stress of the temporary support structure, and the maximum buckling mode generated by the temporary support structure is smaller than the maximum buckling mode of the temporary support structure;
the uniform load F is calculated by the following formula:
F＝A*L*w/2L l
wherein: a represents the cross section area of a transverse bridge to a through long box section; l represents the length of the strip-shaped base; w represents the volume weight of the transverse bridge to the through long box section, and the value is 26kN/m 3 ；L 1 Representing the spacing between two first side vertical struts;
the hoisting equipment adopts a crane, and the calculated value F' of the steel wire tension of the steel wire rope of the crane meets the following conditions:
F′＝G/a*τ*sinα
wherein: g represents the weight of a crane lifting object; a represents the stock number of the crane steel wire rope; τ represents the uneven stress coefficient of the crane steel wire rope, and 0.82 is taken; an included angle of the steel wire rope of the alpha crane relative to the horizontal plane of the crane; and the calculated steel wire tension value F' of the crane steel wire rope is smaller than the table lookup value of the steel wire tension of the crane steel wire rope.
As the preferable scheme of the sectional and block dismantling construction method, the forward bridge sectional excision scheme of the box chamber of the cast-in-situ prestressed box girder comprises two steps of respectively: the forward bridge direction sectional scribing and the forward bridge direction sectional cutting; the scheme of cutting and transferring the transverse bridge block by block comprises two steps, namely scribing the transverse bridge block and cutting and transferring the transverse bridge block; the construction sequence of each step is as follows:
Step 1.1, scribing a box chamber of a cast-in-situ prestressed box girder
Dividing a cast-in-situ prestressed box Liang Yanshun bridge direction into a plurality of transverse bridge direction through-length box girder sections along the transverse bridge direction symmetrical line-marking sections of the cast-in-situ prestressed box girder by taking the forward bridge direction central line of the cast-in-situ prestressed box girder as a basis and taking the roof hogging moment stretching sites of the cast-in-situ prestressed box girder into consideration;
the transverse bridge direction block scribing comprises a top plate transverse bridge direction block scribing and a bottom plate transverse bridge direction block scribing;
dividing and marking the bottom plate transverse bridge direction, namely selecting the connection site of the temporary support structure and the cast-in-situ prestressed box girder as a reference basis for dividing and marking the bottom plate of the cast-in-situ prestressed box girder, so as to divide and mark the bottom plate of the cast-in-situ prestressed box girder along the forward bridge direction of the cast-in-situ prestressed box girder;
dividing and scribing the transverse bridge direction of the top plate, namely selecting a connecting and bending site of the top plate and the web plate of the box structure as a reference basis for dividing and blocking the top plate according to the box structure characteristics of the cast-in-situ prestressed box girder, so as to divide and block the top plate of each section of transverse bridge direction through long box girder section in the cast-in-situ prestressed box girder along the forward bridge direction of the cast-in-situ prestressed box girder;
step 1.2, sectioning, cutting, transferring and transporting the cast-in-situ prestress box girder box chamber in a sectioning mode
Step 1.2.1, cutting and separating the forward bridge of the cast-in-situ prestressed box girder from the middle area by adopting a rope saw cutting mode according to the forward bridge sectional scribing scheme of the step 1;
step 1.2.2, according to the scheme of dividing and scribing the transverse bridge of the top plate in the step 1, adopting a direct breaking method to symmetrically break and remove the top plate part of the forward bridge towards the middle area;
step 1.2.3, according to the scheme of dividing and marking the transverse bridge of the bottom plate in the step 1 into blocks, adopting a rope saw cutting mode under the cooperation of lifting equipment to symmetrically hoist and remove the blocks of the half-bag box chamber outside the bridge towards the middle area;
step 1.2.4, hoisting the center web area blocks from the forward bridge to the middle area by using hoisting equipment;
and (3) removing the rest box chamber parts on two sides of the middle area from the bridge section to section in a mode of step 1.2.1 to step 1.2.4.
The invention provides a sectional block dismantling construction method of a cast-in-situ prestressed box girder, which comprises the following steps:
step one, constructing a segmented and block cutting scheme of a cast-in-situ prestressed box girder
Step 1.1, constructing a temporary support scheme of a cast-in-situ prestressed box girder and selecting specific type lifting equipment
Based on the structural characteristics of the cast-in-situ prestressed box girder and technical considerations of sectional and block dismantling of the cast-in-situ prestressed box girder, constructing a proper temporary support structure and selecting a proper model of lifting equipment;
Step 1.2, constructing a section-by-section block-by-block cutting scheduling scheme
On the premise of comprehensively considering the bearing capacity of the temporary supporting structure and the hoisting capacity of hoisting equipment, a section-by-section block-by-block cutting and transferring scheme of the forward bridge direction section and the transverse bridge direction section is constructed aiming at the box chamber part of the cast-in-situ prestressed box girder;
the section-by-section block-by-block cutting and transferring scheme comprises a forward bridge-to-section cutting and transferring scheme and a transverse bridge-to-block cutting and transferring scheme which are alternately performed; the bridge-wise piecewise cutting scheme is used for symmetrically and sectionally cutting the box chamber part of the cast-in-situ prestressed box girder in a mode from the center to the two sides along the cast-in-situ prestressed box Liang Shunqiao so as to obtain a transverse bridge-wise through long box chamber section at a corresponding cutting position; the transverse bridge longitudinal through long box chamber section is obtained by cutting the transverse bridge longitudinal section-by-section cutting scheme according to the transverse bridge longitudinal through long box chamber section, the transverse bridge longitudinal center line of the transverse bridge longitudinal through long box chamber section is taken as a reference, the transverse bridge longitudinal through long box chamber section is symmetrically removed according to the sequence of the top plate, the outer side half box chamber block and the central web plate area block, the top plate is directly removed through a breaking method, and the outer side half box chamber block and the central web plate area block are cut and transferred through a hoisting device in cooperation with a rope saw cutting method; the method specifically comprises the following steps:
Step 1.2.1, scribing a box chamber of the cast-in-situ prestressed box girder
The box chamber scribing of the cast-in-situ prestressed box girder comprises bridge-direction sectional scribing, bottom plate transverse bridge-direction block scribing and top plate transverse bridge-direction block scribing;
dividing a cast-in-situ prestressed box Liang Yanshun bridge direction into a plurality of transverse bridge direction through-length box girder sections along the transverse bridge direction symmetrical line-marking sections of the cast-in-situ prestressed box girder by taking the forward bridge direction central line of the cast-in-situ prestressed box girder as a basis and taking the roof hogging moment stretching sites of the cast-in-situ prestressed box girder into consideration;
the transverse bridge direction block scribing comprises a top plate transverse bridge direction block scribing and a bottom plate transverse bridge direction block scribing;
dividing and marking the bottom plate transverse bridge direction, namely selecting the connection site of the temporary support structure and the cast-in-situ prestressed box girder as a reference basis for dividing and marking the bottom plate of the cast-in-situ prestressed box girder, so as to divide and mark the bottom plate of the cast-in-situ prestressed box girder along the forward bridge direction of the cast-in-situ prestressed box girder;
dividing and scribing the transverse bridge direction of the top plate, namely selecting a connecting and bending site of the top plate and the web plate of the box structure as a reference basis for dividing and blocking the top plate according to the box structure characteristics of the cast-in-situ prestressed box girder, so as to divide and block the top plate of each section of transverse bridge direction through long box girder section in the cast-in-situ prestressed box girder along the forward bridge direction of the cast-in-situ prestressed box girder;
Step 1.2.2, sectioning, cutting, transferring and transporting the cast-in-situ prestress box girder box chamber in a sectioning mode
Step 1.2.2.1, cutting and separating the forward bridge of the cast-in-situ prestressed box girder to the middle area by adopting a rope saw cutting mode according to the forward bridge direction sectional scribing scheme of step 1.1;
step 1.2.2.2, according to the scheme of dividing and scribing the transverse bridge of the top plate in the step 1.1, adopting a direct breaking method to symmetrically break and remove the top plate part in the middle area along the bridge;
step 1.2.2.3, according to the scheme of dividing and scribing the bottom plate transverse bridge direction blocks in step 1.1, adopting a rope saw cutting mode under the cooperation of lifting equipment to symmetrically hoist and remove the half-package box chamber blocks outside the bridge direction middle area;
step 1.2.2.4, hoisting the center web area blocks from the forward bridge to the middle area by adopting hoisting equipment;
removing the rest box chamber parts from the bridge to the two sides of the middle area section by section and block by block in the mode of steps 1.2.2.1-1.2.2.4;
step 1.3, accounting for the bearing capacity of the temporary support structure and the lifting capacity of the lifting equipment
In the modeling platform, according to the section-by-section block-by-block cutting and dispatching scheme described in the step 1.2, whether the bearing capacity of the temporary supporting structure and the hoisting capacity of the hoisting equipment meet the requirements or not is calculated; if the requirement is not met, returning to the step 1.1 until the calculated bearing capacity of the temporary support structure and the hoisting capacity of the hoisting equipment meet the requirement;
Step two, erecting a temporary support system
According to the temporary support scheme of the cast-in-situ prestressed box girder constructed in the step 1.1, erecting temporary support structures at the lower part of the cast-in-situ prestressed box girder to form a temporary support system of the cast-in-situ prestressed box girder;
step three, sectional block dismantling scribing of cast-in-situ prestress box girder
According to the box chamber scribing scheme of the cast-in-situ prestressed box girder described in the step 1.2.1, scribing is carried out at the corresponding position of the cast-in-situ prestressed box girder;
step four, cutting, transferring and transporting anti-collision wall and wing plates
Symmetrically cutting and transferring the anti-collision walls and wing plates on two sides of the cast-in-situ prestressed box girder box chamber;
step five, constructing and dismantling section by section
According to the sectional block cutting and transferring scheme of the cast-in-situ prestressed box girder and box chamber described in the step 1.2.2, removing the box chamber part of the cast-in-situ prestressed box girder section by section and block by block;
step six, dismantling the temporary support structure
Step seven, dismantling the upright post
And dismantling the upright post of the lower supporting structure of the cast-in-situ prestressed box girder.
And step eight, transporting the crushed slag outwards.
In the step 1.1, the temporary support structures comprise a plurality of temporary support structures, and each temporary support structure is arranged below the cast-in-situ prestressed box girder and is arranged along the transverse bridge direction of the cast-in-situ prestressed box girder;
The temporary support structure be double steel pipe support structure, including bar basis, vertical pillar and horizontal support, wherein:
the vertical support comprises a middle vertical support and a first side vertical support and a second side vertical support which are symmetrically distributed on two sides of the middle vertical support; the vertical struts are connected through connecting brackets;
the bottom plate of the cast-in-situ prestressed box girder is positioned at the middle position of the transverse bridge direction and is supported by the middle vertical support column; the two ends of the bottom plate of the cast-in-situ prestressed box girder in the transverse bridge direction are supported by two groups of first side vertical struts; the outer end part of the box chamber of the cast-in-situ prestressed box girder is supported by two groups of second side vertical struts;
after the box chambers of the cast-in-situ prestressed box girder are cut by a sequential bridge-to-section cutting scheme, the divided transverse bridge applies a temporary support structure load to the through long box chamber section, and the temporary support structure loads uniformly act on the middle vertical support and the first side vertical support positioned at two sides of the middle vertical support;
the modeling platform is used for accounting, the maximum stress generated by the temporary support structure under the action of uniformly distributed load is smaller than the maximum design stress of the temporary support structure, and the maximum buckling mode generated by the temporary support structure is smaller than the maximum buckling mode of the temporary support structure;
The uniform load F is calculated by the following formula:
F＝A*L*w/2L 1
wherein: a represents the cross section area of a transverse bridge to a through long box section; l represents the length of the strip-shaped base; w represents the volume weight of the transverse bridge to the through long box section, and the value is 26kN/m 3 ；L 1 Representing the spacing between two first side vertical struts;
the hoisting equipment adopts a crane, and the calculated value F' of the steel wire tension of the steel wire rope of the crane meets the following conditions:
F′＝G/a*τ*sinα
wherein: g represents the weight of a crane lifting object; a represents the stock number of the crane steel wire rope; τ represents the uneven stress coefficient of the crane steel wire rope, and 0.82 is taken; an included angle of the steel wire rope of the alpha crane relative to the horizontal plane of the crane; and the calculated steel wire tension value F' of the crane steel wire rope is smaller than the table lookup value of the steel wire tension of the crane steel wire rope.
Based on the technical objects, compared with the prior art, the invention has the following advantages:
the invention combines the bridge cutting technology and the bridge structure, utilizes the characteristics of the bridge structure (especially the prestress box girder structure formed by the hanging basket cantilever method), and utilizes the longitudinal bridge segmentation and transverse bridge segmentation modes of the box chamber part of the cast-in-situ prestress box girder to cooperate with a simpler temporary support structure (in fact, by accounting, the temporary support structure is basically only arranged at the position of the lower structure of the bridge structure, and the temporary support structure is arranged in the midspan, so that the aim is only to be careful), and the box chamber part of the cast-in-situ prestress box girder is removed block by block and segment by segment on the premise of not damaging the box girder prestress structure, so that the weight of the box girder is reduced, the self structure safety of the box girder is ensured, the lifting capacity requirement of lifting equipment is effectively reduced, the lifting safety of a crane in a large rotation radius is ensured, the construction difficulty of the temporary support structure is reduced, the construction period is shortened, and the construction safety is ensured. The excision construction method is particularly suitable for dismantling the river-crossing prestressed box girder section which cannot be provided with a bracket in the midspan and the land-based prestressed box girder section which has no sufficient crane station space on two sides.
Drawings
FIG. 1 is a schematic diagram of a three-dimensional structure of an existing cast-in-situ prestressed box girder constructed and formed based on a basket hanging cantilever method;
FIG. 2 is a flow chart of a sectional block dismantling construction method of the cast-in-situ prestressed box girder of the invention;
FIG. 3 is a schematic view of a cast-in-place prestressed box girder with its cross-sectional cut-away;
FIG. 4 is a schematic illustration of a forward bridge sectioning cut of a cast-in-place prestressed box girder according to the present invention;
FIG. 5 is a schematic distribution diagram of temporary support structures of the cast-in-situ prestressed box girder in the breaking process;
FIG. 6 is a schematic view of a cast-in-place prestressed box girder of the present invention supported by a temporary support structure;
wherein: 1-an anti-collision wall; 2-side wing plates; 3-a crushing area of a top plate of the box chamber; 4-a bottom web rupture zone outside the box chamber; 5-a fulcrum rupture zone in the bridge; 61-a first roof separation line; 62-a second roof separation line; 63-a third roof separation line; 64-fourth roof separation line; 65-fifth roof separation line; 66-sixth top plate separation line; 71-a first floor separation line; 72-a second floor separation line; 73-third floor separation line; 74-fourth floor separation line; 81-a box girder section middle area; 82-a region on one side of the tank Liang Duandi; 83-box Liang Duandi on both sides; 84-box Liang Duandi three-sided region; 85-a first roof negative bending moment tensioning position; 86-a second roof hogging moment tensioning position;
91-first side vertical struts; 92-middle vertical struts; 93-second side vertical struts; 94-transverse support.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. The following description of at least one exemplary embodiment is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention. The relative arrangement, expressions and numerical values of the components and steps set forth in these embodiments do not limit the scope of the present invention unless it is specifically stated otherwise. Techniques, methods, and apparatus known to one of ordinary skill in the relevant art may not be discussed in detail, but should be considered part of the specification where appropriate. In all examples shown and discussed herein, any specific values should be construed as merely illustrative, and not a limitation. Thus, other examples of the exemplary embodiments may have different values.
As shown in fig. 1 to 6, the construction method for sectional and block dismantling of a cast-in-situ prestressed box girder according to the present invention is mainly used for dismantling an existing cast-in-situ prestressed box girder as shown in fig. 1, wherein the cast-in-situ prestressed box girder has two boxes, and in the dismantling process, symmetrical dismantling is adopted to ensure construction safety, and the method specifically comprises the following steps:
step one, constructing a segmented and block cutting scheme of a cast-in-situ prestressed box girder
Step 1.1, constructing a temporary support scheme of a cast-in-situ prestressed box girder and selecting specific type lifting equipment
Based on the structural characteristics of the cast-in-situ prestressed box girder and technical considerations of sectional and block dismantling of the cast-in-situ prestressed box girder, constructing a proper temporary support structure and selecting a proper model of lifting equipment;
the temporary support structures comprise a plurality of temporary support structures, and each temporary support structure is arranged below the cast-in-situ prestressed box girder and is arranged along the transverse bridge direction of the cast-in-situ prestressed box girder; in the invention, as shown in fig. 4, five temporary supporting structures are arranged along the forward bridge center line of the cast-in-situ prestressed box girder, the middle region ABCDE of the box girder section at two sides of the forward bridge center line is used for temporarily supporting the temporary supporting structures, the rest four temporary supporting structures are symmetrically arranged at two sides of the forward bridge center line of the cast-in-situ prestressed box girder, and the rest four temporary supporting structures are respectively used for correspondingly supporting the first side region FGH of the box girder section at one side of the forward bridge center line, the two side regions IKJ of the box Liang Duandi and the rest two temporary supporting structures are arranged at the position of the lower supporting structure of the cast-in-situ prestressed box girder and are used for supporting the three side regions of the box Liang Duandi.
The temporary support structure is a double-row steel pipe support structure, as shown in fig. 5, and comprises a strip foundation, a vertical support and a transverse support, wherein:
the vertical support comprises a middle vertical support and a first side vertical support and a second side vertical support which are symmetrically distributed on two sides of the middle vertical support; the vertical struts are connected through connecting brackets;
when the temporary support structure supports the cast-in-situ prestressed box girder, as shown in fig. 6, the bottom plate of the cast-in-situ prestressed box girder is positioned at the middle position of the transverse bridge direction and is supported by the middle vertical support column; the two ends of the bottom plate of the cast-in-situ prestressed box girder in the transverse bridge direction are supported by two groups of first side vertical struts; the outside end of the box chamber of the cast-in-situ prestressed box girder is supported by two groups of second side vertical struts.
After the box chambers of the cast-in-situ prestressed box girder are cut by a sequential bridge-to-section cutting scheme, the divided transverse bridge applies the load of the temporary support structure to the through long box chamber section, and the load acts on the middle vertical support and the first side vertical support positioned at two sides of the middle vertical support uniformly. And through the accounting of the modeling platform, under the action of uniformly distributed load, the generated maximum stress of the temporary support structure is smaller than the maximum design stress of the temporary support structure, and the generated maximum buckling mode is smaller than the maximum buckling mode of the temporary support structure.
The uniform load F is calculated by the following formula:
F＝A*L*w/2L 1
in the middle of: a represents the cross section area of a transverse bridge to a through long box section; l represents the length of the strip-shaped base; w represents the volume weight of the transverse bridge to the through long box section, and the value is 26kN/m 3 ；L 1 Representing the spacing between two first side vertical struts;
the hoisting equipment adopts a crane, and the calculated value F' of the steel wire tension of the steel wire rope of the crane meets the following conditions:
F′＝G/a*τ*sinα
wherein: g represents the weight of a crane lifting object; a represents the stock number of the crane steel wire rope; τ represents the uneven stress coefficient of the crane steel wire rope, and 0.82 is taken; an included angle of the steel wire rope of the alpha crane relative to the horizontal plane of the crane; and the calculated steel wire tension value F' of the crane steel wire rope is smaller than the table lookup value of the steel wire tension of the crane steel wire rope.
Step 1.2, constructing a section-by-section block-by-block cutting scheduling scheme
On the premise of comprehensively considering the bearing capacity of the temporary supporting structure and the hoisting capacity of hoisting equipment, a section-by-section block-by-block cutting and transferring scheme of the forward bridge direction section and the transverse bridge direction section is constructed aiming at the box chamber part of the cast-in-situ prestressed box girder;
the section-by-section block-by-block cutting and transferring scheme comprises a forward bridge-to-section cutting and transferring scheme and a transverse bridge-to-block cutting and transferring scheme which are alternately performed; the bridge-wise piecewise cutting scheme is used for symmetrically and sectionally cutting the box chamber part of the cast-in-situ prestressed box girder in a mode from the center to the two sides along the cast-in-situ prestressed box Liang Shunqiao so as to obtain a transverse bridge-wise through long box chamber section at a corresponding cutting position; the transverse bridge longitudinal through long box chamber section is obtained by cutting the transverse bridge longitudinal section-by-section cutting scheme according to the transverse bridge longitudinal through long box chamber section, the transverse bridge longitudinal center line of the transverse bridge longitudinal through long box chamber section is taken as a reference, the transverse bridge longitudinal through long box chamber section is symmetrically removed according to the sequence of the top plate, the outer side half box chamber block and the central web plate area block, the top plate is directly removed through a breaking method, and the outer side half box chamber block and the central web plate area block are cut and transferred through a hoisting device in cooperation with a rope saw cutting method; the method specifically comprises the following steps:
Step 1.2.1, scribing a box chamber of the cast-in-situ prestressed box girder
The box chamber scribing of the cast-in-situ prestressed box girder comprises bridge-direction sectional scribing, bottom plate transverse bridge-direction block scribing and top plate transverse bridge-direction block scribing;
and (3) forward bridge direction sectional scribing, namely taking a forward bridge direction central line of the cast-in-situ prestressed box girder as a basis, taking a roof hogging moment stretching site (comprising a first roof hogging moment stretching site and a second roof hogging moment stretching site shown in fig. 4) of the cast-in-situ prestressed box girder into consideration, symmetrically scribing and sectioning along a transverse bridge direction of the cast-in-situ prestressed box girder, and dividing the cast-in-situ prestressed box Liang Yanshun into a plurality of transverse bridge direction through long box girder sections. Therefore, the invention combines the existing bridge structure to perform sectional cutting, and on the premise of not damaging the prestress structure of the cast-in-situ prestress box girder, the anti-collision wall, the flange plate and the midspan roof are firstly cut step by step in small blocks, so that the self weight of the box girder is lightened, the self structure safety of the box girder is ensured, the crane can be ensured to be lifted safely in a large rotation radius, namely, the safety accident caused by the collapse of the temporary support structure is reduced, and the construction safety is effectively ensured.
Specifically, as shown in fig. 2 and 4, the bridge-direction sectional scribing of the cast-in-situ prestressed box girder box chamber comprises a first sectional scribing line, a second sectional scribing line, a third sectional scribing line, a fourth sectional scribing line, a fifth sectional scribing line and a sixth sectional scribing line; the first sectioning cutting line, the second sectioning cutting line, the third sectioning cutting line, the fourth sectioning cutting line, the fifth sectioning cutting line and the sixth sectioning cutting line are all arranged along the transverse bridge direction of the box chamber of the cast-in-situ prestressed box girder, the first sectioning cutting line and the second sectioning cutting line are symmetrically distributed about the forward bridge direction central line of the cast-in-situ prestressed box girder, the first sectioning cutting line and the second sectioning cutting line coincide with projection lines of the corresponding negative bending moment of the first top plate on the top plate in the cast-in-situ prestressed box girder, the third sectioning cutting line and the fourth sectioning cutting line are symmetrically distributed about the forward bridge direction central line of the cast-in-situ prestressed box girder, the third sectioning cutting line and the fourth sectioning cutting line coincide with projection lines of the corresponding negative bending moment of the second top plate on the top plate in the cast-in-situ prestressed box girder, and the fifth sectioning cutting line and the sixth sectioning cutting line are symmetrically distributed about the forward bridge direction central line of the cast-in-situ prestressed box girder; the cast-in-situ prestressed box girder is divided into a box girder Duan Zhongbu area, a box Liang Duandi side area, a box girder segment second side area and a box Liang Duandi three side area in sequence from one side of a bridge-wise center line of the cast-in-situ prestressed box girder under the separation of a first subsection cutting line, a second subsection cutting line, a third subsection cutting line, a fourth subsection cutting line, a fifth subsection cutting line and a sixth subsection cutting line, and the three side areas of the box Liang Duandi are adjacent to the lower supporting structure of the cast-in-situ prestressed box girder.
The transverse bridge direction block scribing comprises a top plate transverse bridge direction block scribing and a bottom plate transverse bridge direction block scribing;
and (3) dividing and scribing the bottom plate in the transverse bridge direction, namely selecting the connection site of the temporary support structure and the cast-in-situ prestressed box girder as a reference basis for dividing and scribing the bottom plate of the cast-in-situ prestressed box girder, so as to divide and scribe the bottom plate of the cast-in-situ prestressed box girder along the forward bridge direction of the cast-in-situ prestressed box girder.
Specifically, as shown in fig. 2-3, the floor transverse bridge direction block scribing of the cast-in-situ prestress box girder box chamber comprises a first floor separation line, a second floor separation line, a third floor separation line and a fourth floor separation line; the first bottom plate separation line, the second bottom plate separation line, the third bottom plate separation line and the fourth bottom plate separation line are all arranged along the forward bridge direction of the cast-in-situ prestressed box girder box chamber top plate, the second bottom plate separation line and the third bottom plate separation line are all symmetrically arranged along the transverse bridge direction central line of the cast-in-situ prestressed box girder box chamber, the second bottom plate separation line and the third bottom plate separation line are all overlapped with the transverse bridge direction central line of the cast-in-situ prestressed box girder box chamber bottom plate respectively corresponding to the first bottom plate separation line and the fourth bottom plate separation line, the first bottom plate separation line and the fourth bottom plate separation line are symmetrically arranged relative to the transverse bridge direction central line of the cast-in-situ prestressed box girder box chamber respectively corresponding to the cast-in-situ prestressed box girder box chamber and the wing plate; the temporary support structure has the second side vertical support column disposed immediately adjacent to and inboard of the respective first or fourth floor separation line.
Dividing and scribing the transverse bridge direction of the top plate, namely selecting a connecting and bending site of the top plate and the web plate of the box structure as a reference basis for dividing and blocking the top plate according to the box structure characteristics of the cast-in-situ prestressed box girder, so as to divide and block the top plate of each section of transverse bridge direction through long box girder section in the cast-in-situ prestressed box girder along the forward bridge direction of the cast-in-situ prestressed box girder; the connecting and bending site of the top plate and the web plate of the box chamber structure is selected as the reference basis of the top plate scribing and blocking, and the reason is that in the follow-up dismantling process, the top plate part planned by the scribing is dismantled by adopting a breaking method.
Specifically, as shown in fig. 2 and 3, the top plate transverse bridge direction block scribing of the cast-in-situ prestress box girder box chamber comprises a first top plate separation line, a second top plate separation line, a third top plate separation line, a fourth top plate separation line, a fifth top plate separation line and a sixth top plate separation line, wherein: the first top plate separation line, the second top plate separation line, the third top plate separation line, the fourth top plate separation line, the fifth top plate separation line and the sixth top plate separation line are all arranged along the bridge direction of the top plate of the cast-in-place prestress box girder box chamber, the third top plate separation line and the fourth top plate separation line are symmetrically distributed on two sides of the bridge transverse bridge direction central line, the scribing positions of the third top plate separation line and the fourth top plate separation line coincide with projection lines of the inner side end parts of the top plate horizontal sections of the bridge box chambers respectively, the second top plate separation line and the fifth top plate separation line are symmetrically distributed on two sides of the bridge transverse bridge direction central line, the second top plate separation line and the fifth top plate separation line coincide with projection lines of the outer side end parts of the top plate horizontal sections of the bridge box chambers respectively, the first top plate separation line and the sixth top plate separation line are symmetrically distributed on two sides of the bridge transverse bridge direction central line, and the first top plate separation line and the sixth top plate separation line coincide with projection lines of the inner side end parts of the wing plates respectively corresponding to the bridge; the inner side end of the horizontal section of the top plate is the bending site for connecting the top plate with the inner side web plate, and the outer side end of the horizontal section of the top plate is the bending site for connecting the top plate with the outer side web plate.
Step 1.2.2, sectioning, cutting, transferring and transporting the cast-in-situ prestress box girder box chamber in a sectioning mode
Step 1.2.2.1, cutting and separating the forward bridge of the cast-in-situ prestressed box girder to the middle area by adopting a rope saw cutting mode according to the forward bridge direction sectional scribing scheme of step 1.1;
step 1.2.2.2, according to the scheme of dividing and scribing the transverse bridge of the top plate in the step 1.1, adopting a direct breaking method to symmetrically break and remove the top plate part in the middle area along the bridge;
step 1.2.2.3, according to the scheme of dividing and scribing the bottom plate transverse bridge direction blocks in step 1.1, adopting a rope saw cutting mode under the cooperation of lifting equipment to symmetrically hoist and remove the half-package box chamber blocks outside the bridge direction middle area;
step 1.2.2.4, hoisting the center web area blocks from the forward bridge to the middle area by adopting hoisting equipment;
the remaining chamber parts of the bridge on both sides of the middle region are removed segment by segment in a block-by-block manner in accordance with steps 1.2.2.1-1.2.2.4.
In other words, in the dismantling process, the wing plates and the anti-collision wall at the two sides are dismantled firstly, then the dismantling is carried out on the box chamber part in a mode of firstly cutting transversely and then cutting longitudinally, and the dismantling is generally carried out according to the following sequence:
Ad-Bd-Cd-Dd-Ab-Bb-Cb-Db-E-Fd-Gd-Fd-Gb-H-Ib-Jb-Ib-K-remaining overhanging 4 m-middle beam. (the upper case letter before indicates the block, the lower case letter d after indicates the top plate, and b indicates the bottom plate).
When the block ABD is cut, the first roof hogging moment tension device T2 and the second roof hogging moment tension device T3 are not released, when the block DEF is cut, the second roof hogging moment tension device T3 is released, when the block GHI is cut, the first roof hogging moment tension device T2 is released, and finally the cantilever 5m is cut.
Step 1.3, accounting for the bearing capacity of the temporary support structure and the lifting capacity of the lifting equipment
In the modeling platform, according to the section-by-section block-by-block cutting and dispatching scheme described in the step 1.2, whether the bearing capacity of the temporary supporting structure and the hoisting capacity of the hoisting equipment meet the requirements or not is calculated; if the requirement is not met, returning to the step 1.1 until the calculated bearing capacity of the temporary support structure and the hoisting capacity of the hoisting equipment meet the requirement;
step two, erecting a temporary support system
According to the temporary support scheme of the cast-in-situ prestressed box girder constructed in the step 1.1, erecting temporary support structures at the lower part of the cast-in-situ prestressed box girder to form a temporary support system of the cast-in-situ prestressed box girder;
step three, sectional block dismantling scribing of cast-in-situ prestress box girder
According to the box chamber scribing scheme of the cast-in-situ prestressed box girder described in the step 1.2.1, scribing is carried out at the corresponding position of the cast-in-situ prestressed box girder;
Step four, cutting, transferring and transporting anti-collision wall and wing plates
Symmetrically cutting and transferring the anti-collision walls and wing plates on two sides of the cast-in-situ prestressed box girder box chamber;
step five, constructing and dismantling section by section
According to the sectional block cutting and transferring scheme of the cast-in-situ prestressed box girder and box chamber described in the step 1.2.2, removing the box chamber part of the cast-in-situ prestressed box girder section by section and block by block;
step six, dismantling the temporary support structure
Step seven, dismantling the upright post
And dismantling the upright post of the lower supporting structure of the cast-in-situ prestressed box girder.
And step eight, transporting the crushed slag outwards.
Claims (3)
1. The sectional block dismantling construction method of the cast-in-situ prestressed box girder is characterized by comprising the following steps of:
step one, constructing a segmented and block cutting scheme of a cast-in-situ prestressed box girder
Step 1.1, constructing a temporary support scheme of a cast-in-situ prestressed box girder and selecting a proper type of lifting equipment
Based on the structural characteristics of the cast-in-situ prestressed box girder and technical considerations of sectional and block dismantling of the cast-in-situ prestressed box girder, constructing a proper temporary support structure and selecting a proper model of lifting equipment;
step 1.2, constructing a section-by-section block-by-block cutting scheduling scheme
On the premise of comprehensively considering the bearing capacity of the temporary supporting structure and the hoisting capacity of hoisting equipment, a section-by-section block-by-block cutting and transferring scheme of the forward bridge direction section and the transverse bridge direction section is constructed aiming at the box chamber part of the cast-in-situ prestressed box girder;
The section-by-section block-by-block cutting and transferring scheme comprises a forward bridge-to-section cutting and transferring scheme and a transverse bridge-to-block cutting and transferring scheme which are alternately performed; the bridge-wise piecewise cutting scheme is used for symmetrically and sectionally cutting the box chamber part of the cast-in-situ prestressed box girder in a mode from the center to the two sides along the cast-in-situ prestressed box Liang Shunqiao so as to obtain a transverse bridge-wise through long box chamber section at a corresponding cutting position; the transverse bridge longitudinal through long box chamber section is obtained by cutting the transverse bridge longitudinal section-by-section cutting scheme according to the transverse bridge longitudinal through long box chamber section, the transverse bridge longitudinal center line of the transverse bridge longitudinal through long box chamber section is taken as a reference, the transverse bridge longitudinal through long box chamber section is symmetrically removed according to the sequence of the top plate, the outer side half box chamber block and the central web plate area block, the top plate is directly removed through a breaking method, and the outer side half box chamber block and the central web plate area block are cut and transferred through a hoisting device in cooperation with a rope saw cutting method; the method specifically comprises the following steps:
step 1.2.1, scribing a box chamber of the cast-in-situ prestressed box girder
The box chamber scribing of the cast-in-situ prestressed box girder comprises bridge-direction sectional scribing, bottom plate transverse bridge-direction block scribing and top plate transverse bridge-direction block scribing;
dividing a cast-in-situ prestressed box Liang Yanshun bridge direction into a plurality of transverse bridge direction through-length box girder sections along the transverse bridge direction symmetrical line-marking sections of the cast-in-situ prestressed box girder by taking the forward bridge direction central line of the cast-in-situ prestressed box girder as a basis and taking the roof hogging moment stretching sites of the cast-in-situ prestressed box girder into consideration;
The transverse bridge direction block scribing comprises a top plate transverse bridge direction block scribing and a bottom plate transverse bridge direction block scribing;
dividing and marking the bottom plate transverse bridge direction, namely selecting the connection site of the temporary support structure and the cast-in-situ prestressed box girder as a reference basis for dividing and marking the bottom plate of the cast-in-situ prestressed box girder, so as to divide and mark the bottom plate of the cast-in-situ prestressed box girder along the forward bridge direction of the cast-in-situ prestressed box girder;
dividing and scribing the transverse bridge direction of the top plate, namely selecting a connecting and bending site of the top plate and the web plate of the box structure as a reference basis for dividing and blocking the top plate according to the box structure characteristics of the cast-in-situ prestressed box girder, so as to divide and block the top plate of each section of transverse bridge direction through long box girder section in the cast-in-situ prestressed box girder along the forward bridge direction of the cast-in-situ prestressed box girder;
the bridge-direction sectional scribing of the cast-in-situ prestressed box girder box chamber comprises a first sectional scribing line, a second sectional scribing line, a third sectional scribing line, a fourth sectional scribing line, a fifth sectional scribing line and a sixth sectional scribing line; the first sectioning cutting line, the second sectioning cutting line, the third sectioning cutting line, the fourth sectioning cutting line, the fifth sectioning cutting line and the sixth sectioning cutting line are all arranged along the transverse bridge direction of the box chamber of the cast-in-situ prestressed box girder, the first sectioning cutting line and the second sectioning cutting line are symmetrically distributed about the forward bridge direction central line of the cast-in-situ prestressed box girder, the first sectioning cutting line and the second sectioning cutting line coincide with projection lines of the corresponding negative bending moment of the first top plate on the top plate in the cast-in-situ prestressed box girder, the third sectioning cutting line and the fourth sectioning cutting line are symmetrically distributed about the forward bridge direction central line of the cast-in-situ prestressed box girder, the third sectioning cutting line and the fourth sectioning cutting line coincide with projection lines of the corresponding negative bending moment of the second top plate on the top plate in the cast-in-situ prestressed box girder, and the fifth sectioning cutting line and the sixth sectioning cutting line are symmetrically distributed about the forward bridge direction central line of the cast-in-situ prestressed box girder; the cast-in-situ prestressed box girder is divided into a box girder Duan Zhongbu area, a box Liang Duandi side area, a box girder segment second side area and a box Liang Duandi three side area in sequence from one side of a bridge-wise center line of the cast-in-situ prestressed box girder under the separation of a first subsection cutting line, a second subsection cutting line, a third subsection cutting line, a fourth subsection cutting line, a fifth subsection cutting line and a sixth subsection cutting line, wherein the three side areas of the box Liang Duandi are adjacent to the lower supporting structure of the cast-in-situ prestressed box girder;
The transverse bridge of the top plate of the cast-in-situ prestressed box girder box chamber is divided into blocks and marked to comprise a first top plate separation line, a second top plate separation line, a third top plate separation line, a fourth top plate separation line, a fifth top plate separation line and a sixth top plate separation line, wherein: the first top plate separation line, the second top plate separation line, the third top plate separation line, the fourth top plate separation line, the fifth top plate separation line and the sixth top plate separation line are all arranged along the bridge direction of the top plate of the cast-in-place prestress box girder box chamber, the third top plate separation line and the fourth top plate separation line are symmetrically distributed on two sides of the bridge transverse bridge direction central line, the scribing positions of the third top plate separation line and the fourth top plate separation line coincide with projection lines of the inner side end parts of the top plate horizontal sections of the bridge box chambers respectively, the second top plate separation line and the fifth top plate separation line are symmetrically distributed on two sides of the bridge transverse bridge direction central line, the second top plate separation line and the fifth top plate separation line coincide with projection lines of the outer side end parts of the top plate horizontal sections of the bridge box chambers respectively, the first top plate separation line and the sixth top plate separation line are symmetrically distributed on two sides of the bridge transverse bridge direction central line, and the first top plate separation line and the sixth top plate separation line coincide with projection lines of the inner side end parts of the wing plates respectively corresponding to the bridge; the inner side end of the horizontal section of the top plate is a bending site for connecting the top plate with the inner side web plate, and the outer side end of the horizontal section of the top plate is a bending site for connecting the top plate with the outer side web plate;
The bottom plate transverse bridge direction block scribing of the cast-in-situ prestress box girder box chamber comprises a first bottom plate separation line, a second bottom plate separation line, a third bottom plate separation line and a fourth bottom plate separation line; the first bottom plate separation line, the second bottom plate separation line, the third bottom plate separation line and the fourth bottom plate separation line are all arranged along the forward bridge direction of the cast-in-situ prestressed box girder box chamber top plate, the second bottom plate separation line and the third bottom plate separation line are all symmetrically arranged along the transverse bridge direction central line of the cast-in-situ prestressed box girder box chamber, the second bottom plate separation line and the third bottom plate separation line are all overlapped with the transverse bridge direction central line of the cast-in-situ prestressed box girder box chamber bottom plate respectively corresponding to the first bottom plate separation line and the fourth bottom plate separation line, the first bottom plate separation line and the fourth bottom plate separation line are symmetrically arranged relative to the transverse bridge direction central line of the cast-in-situ prestressed box girder box chamber respectively corresponding to the cast-in-situ prestressed box girder box chamber and the wing plate;
the second side vertical support column is arranged close to the corresponding first bottom plate separation line or fourth bottom plate separation line and is positioned on the inner side of the first bottom plate separation line or the fourth bottom plate separation line;
step 1.2.2, sectioning, cutting, transferring and transporting the cast-in-situ prestress box girder box chamber in a sectioning mode
Step 1.2.2.1, cutting and separating the forward bridge of the cast-in-situ prestressed box girder to the middle area by adopting a rope saw cutting mode according to the forward bridge direction sectional scribing scheme of step 1.1;
step 1.2.2.2, according to the scheme of dividing and scribing the transverse bridge of the top plate in the step 1.1, adopting a direct breaking method to symmetrically break and remove the top plate part in the middle area along the bridge;
step 1.2.2.3, according to the scheme of dividing and scribing the bottom plate transverse bridge direction blocks in step 1.1, adopting a rope saw cutting mode under the cooperation of lifting equipment to symmetrically hoist and remove the half-package box chamber blocks outside the bridge direction middle area;
step 1.2.2.4, hoisting the center web area blocks from the forward bridge to the middle area by adopting hoisting equipment;
removing the rest box chamber parts from the bridge to the two sides of the middle area section by section and block by block in the mode of steps 1.2.2.1-1.2.2.4;
step 1.3, accounting for the bearing capacity of the temporary support structure and the lifting capacity of the lifting equipment
In the modeling platform, according to the section-by-section block-by-block cutting and dispatching scheme described in the step 1.2, whether the bearing capacity of the temporary supporting structure and the hoisting capacity of the hoisting equipment meet the requirements or not is calculated; if the requirement is not met, returning to the step 1.1 until the calculated bearing capacity of the temporary support structure and the hoisting capacity of the hoisting equipment meet the requirement;
Step two, erecting a temporary support system
According to the temporary support scheme of the cast-in-situ prestressed box girder constructed in the step 1.1, erecting temporary support structures at the lower part of the cast-in-situ prestressed box girder to form a temporary support system of the cast-in-situ prestressed box girder;
step three, sectional block dismantling scribing of cast-in-situ prestress box girder
According to the box chamber scribing scheme of the cast-in-situ prestressed box girder described in the step 1.2.1, scribing is carried out at the corresponding position of the cast-in-situ prestressed box girder;
step four, cutting, transferring and transporting anti-collision wall and wing plates
Symmetrically cutting and transferring the anti-collision walls and wing plates on two sides of the cast-in-situ prestressed box girder box chamber;
step five, constructing and dismantling section by section
According to the sectional block cutting and transferring scheme of the cast-in-situ prestressed box girder and box chamber described in the step 1.2.2, removing the box chamber part of the cast-in-situ prestressed box girder section by section and block by block;
step six, dismantling the temporary support structure
Step seven, dismantling the upright post
Dismantling an upright post of a support structure at the lower part of the cast-in-situ prestressed box girder;
and step eight, transporting the crushed slag outwards.
2. The method for sectional and block dismantling construction of a cast-in-situ prestressed box girder according to claim 1, wherein in step 1.1, the temporary support structures comprise a plurality of temporary support structures, and each temporary support structure is arranged below the cast-in-situ prestressed box girder and along the transverse bridge direction of the cast-in-situ prestressed box girder;
The temporary support structure be double steel pipe support structure, including bar basis, vertical pillar and horizontal support, wherein:
the vertical support comprises a middle vertical support and a first side vertical support and a second side vertical support which are symmetrically distributed on two sides of the middle vertical support; the vertical struts are connected through connecting brackets;
the bottom plate of the cast-in-situ prestressed box girder is positioned at the middle position of the transverse bridge direction and is supported by the middle vertical support column; the two ends of the bottom plate of the cast-in-situ prestressed box girder in the transverse bridge direction are supported by two groups of first side vertical struts; the outer end part of the box chamber of the cast-in-situ prestressed box girder is supported by two groups of second side vertical struts;
after the box chambers of the cast-in-situ prestressed box girder are cut by a sequential bridge-to-section cutting scheme, the divided transverse bridge applies a temporary support structure load to the through long box chamber section, and the temporary support structure loads uniformly act on the middle vertical support and the first side vertical support positioned at two sides of the middle vertical support;
the modeling platform is used for accounting, the maximum stress generated by the temporary support structure under the action of uniformly distributed load is smaller than the maximum design stress of the temporary support structure, and the maximum buckling mode generated by the temporary support structure is smaller than the maximum buckling mode of the temporary support structure;
Uniform loadFCalculated by the following formula:
；
wherein:Arepresenting the cross-sectional area of the cross bridge to the through-length box section;Lrepresenting the length of the strip-shaped base;wrepresenting the volume weight of the transverse bridge to the through long box section, and taking the value of 26 kN/m;representing the spacing between two first side vertical struts;
the hoisting equipment adopts a crane, and the calculated value of the steel wire tension of the steel wire rope of the craneFAnd (d) satisfying:
；
wherein:Grepresenting the weight of a crane lifting object;the strand number of the crane steel wire rope is represented; />The uneven stress coefficient of the crane steel wire rope is represented, and 0.82 is taken; />The included angle of the crane steel wire rope relative to the horizontal plane of the crane; calculated steel wire tension value of crane steel wire ropeFIs smaller than the table-checking value of the steel wire tension of the steel wire rope of the crane
3. The method for sectional and block dismantling of a cast-in-situ prestressed box girder according to claim 1, wherein in the fourth step, when the wing plates are resected, the cutting sequence is firstly transverse bridge cutting and finally longitudinal bridge cutting.
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