Multi-span continuous tension prestress fish-belly sill supporting structure and construction method

Abstract

The invention discloses a multi-span continuous tensioning prestress fish-belly sill supporting structure and a construction method, and relates to the technical field of civil engineering. The problem that an existing prestress fish-belly sill supporting system is complex in structure is solved, and the problems that due to the fact that prestress of the steel strands needs to be applied in a segmented mode, construction time is prolonged, and foundation pit deformation control is not facilitated are solved. The supporting structure comprises a plurality of sections of fish-belly sills, a bogie, diagonal bracings, a steel strand and two anchorage devices, the steering frame and the diagonal bracings are arranged at the joint of the two adjacent sections of fish-bellied sills, and the diagonal bracings abut against the fish-bellied sills; the two anchorage devices are respectively arranged at angle braces at the corners of the foundation pit; the fish-belly sill comprises a string beam and a plurality of web member parts arranged on one side of the string beam; a first roller is arranged at the end part of the web member part; one end of the steel strand is connected to one anchorage device, and the other end of the steel strand penetrates through the first idler wheel of the web member component of each section of the fish-belly sill and the bogie and then is anchored to the other anchorage device. The invention further provides a construction method of the supporting structure.

Description

Technical Field

[0001] The present application relates to the field of civil engineering technology, and in particular to a multi-span continuous tensioned prestressed fish belly beam support structure and a construction method. Background Art

[0002] The prestressed fish belly beam support structure can reduce the number of supports and columns inside the foundation pit, provide an open space for the excavation of the soil inside the foundation pit, and can greatly reduce the amount of steel compared with the traditional steel support system. Secondly, due to the constraints of construction site conditions and project costs, it is impossible to install steel supports or concrete supports inside the foundation pit, or anchor rods or soil nails cannot be installed outside the foundation pit due to the constraints of adjacent buildings (structures). At this time, the fish belly beam support structure has a large span, does not occupy the space outside the pit, occupies less space inside the pit, and has less impact on the construction inside the pit. The application of such features in the foundation pit project is gradually increasing. However, due to the constraints of existing materials and technologies, the prestressed fish belly beams currently used in foundation pit projects are all segmented, with each span of about 20 to 40 meters. When the side length of the foundation pit is long, multiple sections of fish belly beams need to be set up, and independent prestressed anchors need to be set at both ends of each section of the fish belly beam. When installing anchors on both sides of the bracing ends, the structure of the bracing ends needs to be partially strengthened, which makes the fish belly beam support structure complicated, and the prestressing of each section of the fish belly beam steel strand needs to be applied in sections, which not only increases the erection time of the fish belly beam support structure, but also has an adverse effect on the deformation control of the foundation pit. Summary of the invention

[0003] The embodiments of the present application provide a multi-span continuous tensioned prestressed fish belly beam support structure and a construction method, which not only solves the problem of complex structure of the existing prestressed fish belly beam support system, but also solves the problem of increased construction time and disadvantageous foundation pit deformation control due to the need to apply the prestress of the steel strands in sections.

[0004] To achieve the above-mentioned objectives, on the one hand, an embodiment of the present application provides a multi-span continuous tensioned prestressed fish beam support structure, comprising a plurality of sections of fish beams, a bogie, a brace, a steel strand and two anchors; the bogie and the brace are both arranged at the connection between two adjacent sections of the fish beam, and the brace is abutted against the fish beam; the two anchors are respectively arranged at the angle braces at the corners of the foundation pit; the fish beam comprises a chord beam and a plurality of web components arranged on one side of the chord beam; a first roller is provided at the end of the web component; one end of the steel strand is connected to one of the anchors, and the other end is anchored to the other anchor after passing through the first roller and the bogie of the web component of each section of the fish beam.

[0005] Furthermore, the bogie includes an arched frame and a plurality of second rollers arranged on the surface of the arched frame; the plurality of second rollers are arranged in an arc-shaped array with a high middle and low ends.

[0006] Furthermore, the arch frame includes a connecting plate, an arc-shaped plate, a plurality of ribs and a plurality of stiffening plates; the plurality of ribs are sequentially arranged on the surface of the connecting plate, and the stiffening plate is arranged between two adjacent ribs; the arc-shaped plate is arranged on the side of the connecting plate and is welded to both ends of the connecting plate and one end of the rib; the side of the connecting plate is connected to the support; and a plurality of second rollers are arranged on the arc-shaped plate.

[0007] Furthermore, the anchor is connected to the corner brace at the corner of the foundation pit by bolts.

[0008] Furthermore, the web member comprises a straight web and diagonal webs arranged on both sides of the straight web; two ends of the diagonal web are respectively connected to the straight web and the chord beam.

[0009] Furthermore, the angle brace includes an angle brace prestressed loading beam; the counter brace includes an counter brace prestressed loading beam; and the bogie is connected to the counter brace prestressed loading beam.

[0010] Furthermore, the braces are arranged in the horizontal direction and supported by lattice columns arranged in the vertical direction; a plurality of corbels and brackets are also arranged on the lattice columns.

[0011] Furthermore, the number of the fish belly beams is three; the number of the bogies and the number of the braces are both two.

[0012] On the other hand, an embodiment of the present application also provides a construction method for the above-mentioned multi-span continuous tensioned prestressed fish belly beam support structure, including the following steps: S1, excavating a foundation pit and pouring reinforced concrete purlins or installing steel purlins in the foundation pit; S2, installing braces and installing bogies at the ends of the braces; S3, installing angle braces and connecting anchors to the purlins and angle braces; S4, connecting multiple sections of fish belly beams to the purlins; S5, passing the steel strand around the first roller and the bogie at the end of the web component of the fish belly beam and inserting it into the anchor; S6, applying prestress to both ends of the steel strand at the same time, and anchoring the steel strand to the anchor after reaching the design stress value.

[0013] Furthermore, the web member component includes a straight web and an oblique web arranged on both sides of the straight web; step S4 specifically includes: S41, connecting the chord beam and the surrounding purlin in each section of the fish belly beam; S42, connecting the straight web and the chord beam in each section of the fish belly beam; S43, connecting the oblique web in each section of the fish belly beam to the straight web and the chord beam respectively.

[0014] Compared with the prior art, this application has the following beneficial effects:

[0015] Compared with the prior art, the multi-span continuous tensioned prestressed fish beam support structure of the embodiment of the present application not only eliminates the anchors at the ends of the braces, but also sets a bogie at the ends of the braces, passes the steel strands from one end of the foundation pit through the fish beam, bogie and fish beam in sequence, and anchors them to the anchors at both ends of the foundation pit. The steel strands on each side of the foundation pit only need to be tensioned once. This method can greatly simplify the construction process of applying prestress to the fish beam steel strands on site and removing the fish beam later, improve the installation efficiency of fish beams in large foundation pits, and help control the deformation caused by foundation pit excavation. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0017] Figure 1 This is a schematic structural diagram of a multi-span continuous tensioned prestressed fish belly beam support structure according to an embodiment of the present application;

[0018] Figure 2 for Figure 1 A partial enlarged view of point Ⅰ in the middle;

[0019] Figure 3 for Figure 1 A partial enlarged view of the middle II;

[0020] Figure 4 This is a schematic diagram of the structure of the bogie in the multi-span continuous tensioned prestressed fish belly beam support structure of the embodiment of the present application. DETAILED DESCRIPTION

[0021] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0022] In the description of the present application, it should be understood that the terms "center", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0023] In the description of the present application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected" and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection. For ordinary technicians in this field, they can understand the specific meanings of the above terms in this application according to specific circumstances.

[0024] The terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" can explicitly or implicitly include one or more of the features. In the description of this application, unless otherwise specified, "plurality" means two or more.

[0025] At present, each section of the fish belly beam is an independent unit, and the prestress of each section needs to be tensioned separately. Anchors need to be installed at both ends of each unit fish belly beam, and the tensioning and disassembly process is cumbersome. When installing anchors on both sides of the brace end, the structure of the brace end needs to be partially strengthened, making the structure of the brace end complex and the prestressing process cumbersome.

[0026] Reference Figures 1 to 4 , an embodiment of the present application provides a multi-span continuous tensioned prestressed fish belly beam support structure, including three sections of fish belly beams 1, two bogies 2, steel strands 3, two groups of braces 4 and two anchors 5. The support structure is arranged in the horizontal direction, that is, the fish belly beam 1 extends in the left-right direction, and the braces 4 extend in the front-back direction. It should be noted that the number of fish belly beams 1 can be determined according to the actual working conditions, and can also be one section or four sections, etc., which is not limited here. The number of bogies 2 and braces 4 is one less than the number of fish belly beams 1. In addition, during actual installation, the multi-span continuous tensioned prestressed fish belly beam support structure in the embodiment of the present application is generally symmetrically arranged, that is, the fish belly beam 1, bogies 2, steel strands 3 and anchors 5 are all symmetrically arranged, and the symmetrical structures on both sides share the braces 4.

[0027] A purlin 7 is provided in the foundation pit. Specifically, a reinforced concrete purlin can be cast or a steel purlin can be installed. The purlin 7 is next to the pile row 8, and in actual engineering, the pile row 8 can also be replaced by other enclosure structures such as underground continuous walls.

[0028] The fish belly beam 1 includes a chord beam 11 and a plurality of web members arranged on the side of the chord beam 11. The chord beam 11 is connected to the surface of the surrounding purlin 7 in the foundation pit by high-strength bolts. The web members include a straight web member 12 and an inclined web member 13 arranged on both sides of the straight web member 12. The end of the straight web member 12 is provided with a first roller (not shown in the figure). The first roller can reduce the prestress loss caused by friction resistance when the steel strand 3 is tensioned. The two ends of the inclined web member 13 are respectively connected to the straight web member 12 and the chord beam 11.

[0029] The bogie 2 and the brace 4 are both arranged at the rear of the connection between two adjacent sections of the fish belly beam 1. Specifically, the brace 4 includes a brace prestressed loading beam 41. The front section of the brace 4 is connected to the bogie 2 by bolts. The bogie 2 is connected to the brace 4 by bolts.

[0030] Reference Figure 4 The bogie 2 includes an arch frame 21 and a plurality of second rollers 22 arranged on the upper surface of the arch frame 21. Specifically, the arch frame 21 includes a connecting plate 211, an arc plate 212, a plurality of ribs 213 and a plurality of stiffening plates 214. The arc plate 212 is arranged on the front side of the connecting plate 211 and connected to both ends of the connecting plate 211. A plurality of ribs 213 are arranged in sequence between the connecting plate 211 and the arc plate 212, and the stiffening plate 214 is arranged between two adjacent ribs 213, or between the ribs 213 and the arc plate 212. The rear surface of the connecting plate 211 is connected to support the prestressed loading beam 41 by bolts. The plurality of second rollers 22 are all arranged on the arc plate 212, and are arranged in an arc array with a high middle and low ends. The second roller 22 and the first roller are located in the same horizontal plane. A bearing 23 is arranged in the second roller 22.

[0031] Reference Figure 3 The two anchors 5 are respectively arranged on the outside of the fish belly beam 1 at both ends, and are connected to the surrounding purlin 7 and the angle brace 6 in the foundation pit. The two ends of the angle brace 6 are respectively connected to the surrounding purlin 7, and the angle brace 6 includes an angle brace prestressed loading beam 61.

[0032] The steel strand 3 passes through the first roller on each section of the fish beam 1 and the second roller 22 on the bogie 2 and is anchored on the two anchors 5 .

[0033] The braces 4 in the fish belly beam support structure of the embodiment of the present application are supported by lattice columns 43 . Specifically, the lattice columns 43 are arranged in the vertical direction, and a plurality of corbels 44 and brackets 45 are provided on the lattice columns 43 .

[0034] On the other hand, an embodiment of the present application further provides a construction method of the above-mentioned multi-span continuous tensioned prestressed fish belly beam 1 support structure, comprising the following steps:

[0035] Step 1: Excavate the foundation pit and cast reinforced concrete purlins or install steel purlins in the foundation pit:

[0036] Excavate the soil inside the foundation pit to the designed elevation according to the construction plan, and level the soil at the bottom of the foundation pit in the area where the angle brace 6, fish belly beam 1 and brace 4 need to be erected; then cast reinforced concrete purlins or install steel purlins at the designed elevation. When using cast-in-place reinforced concrete purlins, ensure that the sides of the purlins are straight.

[0037] Step 2: Install the bracket 44 and the bracket 45:

[0038] The corbel 44 and the bracket 45 are hoisted and fixed to the predetermined position of the lattice column 43 with high-strength bolts. During installation, ensure that the tops of the corbel 44 and the bracket 45 are level.

[0039] Step 3: Install the brace 4 and install the bogie 2 at the end of the brace 4:

[0040] Lift and splice the brace 4 between the two span fish belly beams 1, install the bogie 2 at the end of the brace 4, and install it according to the designed elevation. During the installation process, strictly control the straightness of the plane of the brace 4, and use steel plates to pad the gaps of the splicing of the brace 4.

[0041] Step 4: Install the angle brace 6 and connect the anchor 5 with the purlin 7 and the angle brace 6:

[0042] Hoist and splice the angle braces 6 at both ends of the foundation pit and install them according to the designed elevation. During the installation process, strictly control the straightness of the plane of the angle brace 6, and tighten the gap of the angle brace 6 with a steel plate; then use high-strength bolts to connect the anchor 5 with the purlin 7 and the angle brace 6.

[0043] Step 5: Connect the multi-section fish belly beam 1 with the surrounding purlin 7:

[0044] Step 5.1, connect the string beam 11 and the surrounding purlin 7 in each section of the fish belly beam 1:

[0045] The chord beam 11 and the surrounding purlin 7 of each span are connected with high-strength bolts. During installation, ensure that the chord beam 11 and the surrounding purlin 7 are tightly fitted, and the chord beam 11 and the surrounding purlin 7 are padded with steel plates.

[0046] Step 5.2, sequentially connect the straight web 12 and the string beam 11 in each section of the fish belly beam 1 with high-strength bolts;

[0047] Step 5.3, sequentially connect the diagonal web members 13 in each section of the fish beam 1 with the straight web members 12 and the chord beam 11 respectively using high-strength bolts.

[0048] Step 6: Pass the steel strand 3 through the first roller and the bogie 2 at the end of the straight web of the fish beam 1 and insert it into the anchors 5 at both ends:

[0049] The steel strand 3 is sequentially passed through the first roller at the end of the straight web 12 of the first group of fish beams 1, the second roller 22 of the bogie 2 at the end of the first group of support 4, the first roller of the second group of fish beams 1, the second roller 22 of the second group of bogies 2, and the first roller of the third group of fish beams 1, and then inserted into the anchors 5 on both sides.

[0050] Step 7: gradually apply prestress to the end of the steel strand 3 to the design value according to the design requirements, and anchor and lock the steel strand 3 to the anchors 5 at both ends of the foundation pit.

[0051] The present application can simplify the tensioning and disassembly process of the prestressed anchor cables of the fish belly beam support structure system, improve the installation efficiency of the fish belly beam support structure of a large foundation pit, and has a good effect on controlling the deformation of the foundation pit.

[0052] The above are only specific implementations of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A multi-span continuous tension prestressed fish belly beam support structure, characterized in that: It includes multiple sections of fish belly beams, bogies, braces, steel strands and two anchors; the bogies and the braces are both arranged at the connection between two adjacent sections of fish belly beams, and the braces are in contact with the fish belly beams; the two anchors are respectively arranged at the angle braces at the corners of the foundation pit; the fish belly beam includes a chord beam and multiple web rod components arranged on one side of the chord beam; a first roller is provided at the end of the web rod component; one end of the steel strand is connected to one of the anchors, and the other end passes through the first roller of the web rod component of each section of the fish belly beam and the bogie and is anchored to the other anchor.

2. The multi-span continuous tensioned prestressed fish belly beam support structure according to claim 1 is characterized in that: The bogie comprises an arched frame and a plurality of second rollers arranged on the surface of the arched frame; the plurality of second rollers are arranged in an arc array with a high middle and low ends.

3. The multi-span continuous tensioned prestressed fish belly beam support structure according to claim 2 is characterized in that: The arch frame includes a connecting plate, an arc-shaped plate, a plurality of ribs and a plurality of stiffening plates; the plurality of ribs are sequentially arranged on the surface of the connecting plate, and the stiffening plate is arranged between two adjacent ribs; the arc-shaped plate is arranged on the side of the connecting plate and is welded to both ends of the connecting plate and the upper end of the rib; the side of the connecting plate is connected to the support; and a plurality of second rollers are arranged on the arc-shaped plate.

4. The multi-span continuous tensioned prestressed fish belly beam support structure according to claim 3 is characterized in that: The anchor is connected to the corner brace at the corner of the foundation pit through bolts.

5. The multi-span continuous tensioned prestressed fish belly beam support structure according to claim 4 is characterized in that: The web member comprises a straight web and diagonal webs arranged on both sides of the straight web; two ends of the diagonal web are respectively connected to the straight web and the chord beam.

6. The multi-span continuous tensioned prestressed fish belly beam support structure according to claim 5, characterized in that: The angle brace includes an angle brace prestressed loading beam; the counter brace includes an counter brace prestressed loading beam; and the bogie is connected to the counter brace prestressed loading beam.

7. The multi-span continuous tensioned prestressed fish belly beam support structure according to claim 6 is characterized in that: The braces are arranged in the horizontal direction and supported by lattice columns arranged in the vertical direction; a plurality of corbels and brackets are also arranged on the lattice columns.

8. The multi-span continuous tensioned prestressed fish belly beam support structure according to claim 7 is characterized in that: The number of the fish belly beam is three; the number of the bogie and the brace are both two.

9. A construction method for a multi-span continuous prestressed fish belly beam support structure according to any one of claims 1 to 8, characterized in that: The following steps are involved: S1. Excavate the foundation pit and cast reinforced concrete purlins or install steel purlins in the foundation pit; S2. Install the brace and install the bogie at the end of the brace; S3, install the angle brace and connect the anchor with the purlin and the angle brace; S4, connecting the multiple sections of fish belly beams with the perimeter purlins; S5, passing the steel strand around the first roller and the bogie at the end of the belly rod component of the fish belly beam and inserting it into the anchor; S6. Apply prestress to both ends of the steel strand at the same time, and anchor the steel strand to the anchor after reaching the design stress value.

10. The construction method according to claim 9, characterized in that: The web member includes a straight web and oblique webs arranged on both sides of the straight web; step S4 specifically includes: S41, connecting the string beam and the surrounding purlin in each section of the fish belly beam; S42, connecting the straight web and the string beam in each section of the fish belly beam; S43. Connect the oblique webs in each section of the fish beam to the straight webs and the string beam respectively.

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