CN219527660U - Full-assembled large-span steel structure soft soil deep foundation pit supporting structure - Google Patents

Full-assembled large-span steel structure soft soil deep foundation pit supporting structure Download PDF

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Publication number
CN219527660U
CN219527660U CN202222469589.2U CN202222469589U CN219527660U CN 219527660 U CN219527660 U CN 219527660U CN 202222469589 U CN202222469589 U CN 202222469589U CN 219527660 U CN219527660 U CN 219527660U
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China
Prior art keywords
steel
foundation pit
prestress
lower chord
soft soil
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CN202222469589.2U
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Inventor
林焱
林思远
吴喆
吴理强
潘钜招
刘斐然
贾书岭
唐波
孙乐
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China Road and Bridge Corp
Shanghai Qiangjin Foundation Engineering Co Ltd
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China Road and Bridge Corp
Shanghai Qiangjin Foundation Engineering Co Ltd
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Abstract

The fully assembled large-span steel structure soft soil deep foundation pit supporting structure adopts steel sheet piles as retaining structures and water-stopping enclosing structures, adopts section steel standardized components to assemble and form a horizontal truss structure as a horizontal support, and comprises angle braces and prestressed enclosing purlins; the prestress enclosing purlin and the angle brace are connected into a whole, the stress axes of the prestress enclosing purlin and the angle brace are on the same plane, and the angle brace is provided with a pressure-adjustable pressurizing device; the prestress enclosing purlin comprises a lower chord beam, a web member is arranged on the lower chord beam and extends to the inner side of a foundation pit, steel strands are arranged at the top of the web member, two ends of each steel strand are connected with two ends of the lower chord beam, and the steel strands and the lower chord beam form a closed fish belly structure; the lower chord beam is closely attached to the steel sheet pile. The structure has the advantages of assembled structure, large rigidity, large span, controllable deformation, convenient construction, environment-friendly material recycling, and the like.

Description

Full-assembled large-span steel structure soft soil deep foundation pit supporting structure
Technical Field
The utility model relates to the technical field of civil engineering, in particular to a fully assembled large-span steel structure soft soil deep foundation pit supporting structure.
Background
With the large-scale construction of high-rise building basements, civil air defense projects, subways, tunnels and other municipal infrastructure, the periphery of many deep foundation pits has the characteristics of dense buildings, numerous underground pipelines, high environmental protection requirements and the like, and particularly, the supporting construction method of the deep foundation pit projects more serious challenges under the condition that accidents of soft soil deep foundation pits frequently occur.
In the soft soil deep foundation pit engineering, a common vertical enclosure structure is a drilled and poured concrete pile and a cement-soil mixing pile waterproof curtain or an underground reinforced concrete continuous wall. The construction of both enclosures creates significant mud and waste discharge, requiring the use of significant amounts of steel and concrete materials and permanent retention in the formation. The common horizontal support is a reinforced concrete structure or a steel structure welded on site, the installation and the dismantling time are long, and a large amount of construction waste is generated during the dismantling.
Disclosure of Invention
The utility model aims to solve the technical problems in the prior art and provide a fully assembled large-span steel structure soft soil deep foundation pit supporting structure.
In order to solve the problems, the technical scheme of the utility model is as follows:
the fully assembled large-span steel structure soft soil deep foundation pit supporting structure adopts steel sheet piles as retaining structures and water-stopping building enclosures, and adopts section steel standardized members to assemble and form a horizontal truss structure as a horizontal support, wherein the horizontal support comprises a gusset and a prestressed enclosing purlin; the prestress enclosing purlin and the angle brace are connected into a whole, the stress axes of the prestress enclosing purlin and the angle brace are on the same plane, and a pressure-adjustable pressurizing device is arranged on the opposite brace; the prestress enclosing purlin comprises a lower chord beam, a web member is arranged on the lower chord beam and extends to the inner side of a foundation pit, steel strands are arranged at the top of the web member, two ends of each steel strand are connected with two ends of the lower chord beam, and the steel strands and the lower chord beam form a closed fish belly structure; the lower chord beam is closely attached to the steel sheet pile.
The steel sheet piles are Larson steel sheet piles which are meshed with each other.
The steel sheet pile is a steel pipe pile or a steel pipe and steel sheet combined pile which are connected with each other.
The steel sheet pile inboard sets up shaped steel and encloses the purlin, and the lower string roof beam encloses the purlin laminating with shaped steel.
The gusset and the prestressed purlin are connected with a cross beam, the cross beam is arranged on the upright posts, and the upright posts are connected by a pull rod.
The pull rod is a section steel, a steel strand or a steel wire rope.
The pressurizing device is a self-locking oil cylinder.
All steel members are interconnected using bolts.
The construction method of the fully assembled large-span steel structure soft soil deep foundation pit supporting structure comprises the following steps:
1) Measuring and positioning;
2) Constructing an enclosure structure;
adopting steel sheet piles as an enclosure structure for retaining soil and stopping water; the steel sheet piles are mutually meshed steel sheet piles, the depth of each steel sheet pile is required to meet the stability requirement of soil blocking, and more than one prestressed fish web beam or a large-span high-rigidity assembled steel support enclosing purlin is arranged in each steel sheet pile;
3) Constructing an upright post;
the upright post is of a steel structure, a water stop sheet is arranged in the range of penetrating through the bottom plate, and the upright post is inserted into the jet grouting pile below the pit bottom;
4) Mounting brackets, brackets and joists;
5) Installing a prestressed enclosing purlin;
assembling the prestressed enclosing purlin in situ; the prestress enclosing purlin is connected with the joist by adopting a U-shaped clamp.
6) Installing a horizontal support;
7) Installing a force transmission piece;
8) Checking the installation quality;
9) Digging a foundation pit;
pre-stressing of the steel support is added according to the foundation pit deformation control requirement in the excavation process;
10 After the support replacement or the force transmission belt is completed, releasing the prestress of the steel support;
11 Steel support removal and recovery.
The full-assembled large-span steel structure foundation pit supporting structure has the beneficial effects that the steel structure is assembled by adopting standardized steel members, the installation and dismantling time is short, and the full-assembled large-span steel structure foundation pit supporting structure can be reused. In addition, the advantage of higher bending rigidity can be generated by utilizing the prestress truss structure, and a large-span supporting structure is assembled by standardized steel members, so that a wide working surface space is provided for excavation of a foundation pit and construction of a basement.
The section shape of the steel sheet pile and higher bending strength and rigidity generated when the steel sheet pile is mutually meshed, and the continuous structure formed by assembling the steel sheet pile has the function of a waterproof curtain, so that the functions of a traditional reinforced concrete pile arrangement structure and a continuous cement soil mixing pile or a jet grouting pile are replaced, the basement space occupied by a vertical enclosure structure is reduced, and the land utilization rate is improved. The connection between the vertical steel sheet pile structure and the horizontal steel supporting structure and the installation of the bracket can realize assembly, thereby providing conditions for shortening the construction period of the supporting structure.
Drawings
The utility model is described in detail below with reference to the drawings and the detailed description;
fig. 1 is a schematic overall view of an internal support system.
FIG. 2 is a schematic illustration of a prestressed purlin structure.
Fig. 3 is a construction flow chart of prestressing.
Detailed Description
The utility model is further described with reference to the following detailed drawings in order to make the technical means, the creation characteristics, the achievement of the purpose and the effect of the implementation of the utility model easy to understand.
Referring to fig. 1, the supporting structure in this embodiment mainly comprises a prestressed steel enclosing purlin 1 and a plurality of gussets 2, and steel sheet piles 3 are used as the enclosing structure for retaining soil and stopping water.
The section shape of the steel sheet pile and higher bending strength and rigidity generated when the steel sheet pile is mutually meshed, and the continuous structure formed by assembling the steel sheet pile has the function of a waterproof curtain, so that the functions of a traditional reinforced concrete pile arrangement structure and a continuous cement soil mixing pile or a jet grouting pile are replaced, the basement space occupied by a vertical enclosure structure is reduced, and the land utilization rate is improved. The connection between the vertical steel sheet pile structure and the horizontal steel supporting structure and the installation of the bracket can realize assembly, thereby providing conditions for shortening the construction period of the supporting structure.
Referring to fig. 2, the prestressed steel purlin structure comprises a lower chord beam 11, steel strands 12, web members 13 and special anchors 14.
The web member 13 is arranged on the bridge 11, two ends of the steel stranded wire 12 are connected with two ends of the lower bridge 11, and the middle part of the steel stranded wire 12 is supported by the web member 13 to be in a fish belly shape or an arc shape. The steel and the steel stranded wires are assembled into the enclosing purlin with the fish belly-shaped structure, and prestress is applied to the steel stranded wires, so that the purposes of increasing the span of the enclosing purlin, increasing the rigidity of the enclosing purlin and controlling the horizontal deformation of a foundation pit are achieved.
The steel stranded wires 12 are a plurality of, and the steel stranded wires 12 are composed of a plurality of high-strength low-relaxation steel bars. The steel strands 12 are in smooth contact with the web members 13, and a plurality of steel strands 12 are layered. The steel strand 12 is provided with dedicated anchors 14 at both ends.
The steel strand is prestressed by adopting a pulling method and locked in a special anchorage device, so that the prestress of the steel strand is maintained.
The steel strand consists of a plurality of high-strength low-relaxation steel bars.
The steel strands are in smooth contact with the web members, and a plurality of steel strands are arranged in layers.
The gusset and the prestressed purlin are connected with a cross beam, the cross beam is arranged on the upright posts, and the upright posts are connected by a pull rod.
The pull rod is a section steel, a steel strand or a steel wire rope.
The pressurizing device is a self-locking oil cylinder.
The construction method of the fully assembled large-span steel structure soft soil deep foundation pit supporting structure comprises the following steps:
1) Measuring and positioning;
2) Constructing an enclosure structure;
adopting steel sheet piles as an enclosure structure for retaining soil and stopping water; the steel sheet piles are mutually meshed steel sheet piles, the depth of each steel sheet pile meets the stability requirement of a supporting slope, and four prestress fish web beam assembly type steel supports are arranged in each steel sheet pile;
3) Constructing an upright post;
the upright post is of a steel structure, a water stop sheet is arranged in the range of penetrating through the bottom plate, and the upright post is inserted into the jet grouting pile below the pit bottom;
4) Mounting brackets, brackets and joists;
5) Installing a prestressed enclosing purlin;
assembling the prestressed enclosing purlin in situ; the prestress enclosing purlin is connected with the joist by adopting a U-shaped clamp.
6) Installing a horizontal support;
7) Installing a force transmission piece;
8) Checking the installation quality;
9) Digging a foundation pit;
pre-stressing of the steel support is added according to the foundation pit deformation control requirement in the excavation process;
10 After the support replacement or the force transmission belt is completed, releasing the prestress of the steel support;
11 Steel support removal and recovery.
Tool type combined internal support construction sequence for prestressed fish web girder and prestressing force applying and releasing sequence
1. The construction sequence is as follows: construction preparation, material approach, building enclosure construction, column pile construction, steel support installation working face excavation, fish web beam steel support installation (setting of monitoring points), prestress application, steel strand tensioning, earthwork excavation to a second support bottom position, prestress application, steel strand tensioning, earthwork excavation to a third support bottom position, prestress application, steel strand tensioning, earthwork excavation to a fourth support bottom position, prestress application, steel strand tensioning, earthwork excavation to a pit bottom position, cushion layer, bottom plate and bottom plate support belt replacement construction, fourth steel support prestress unloading and disassembly and recovery, third steel support prestress unloading and disassembly and recovery, second layer basement bottom plate and floor support belt replacement construction, second steel support prestress unloading and disassembly and recovery, first layer basement bottom plate and floor support belt replacement construction, first steel support prestress unloading and disassembly and recovery, steel column above the bottom plate and construction of a residual basement main body structure.
2. In the construction sequence process, after the prestress (see the supporting plane layout) is applied to the position according to the design rule, the lower earthwork can be excavated, and after the bottom plate, the middle floor slab concrete and the force transfer belt concrete reach 90% of the design strength, the steel supports at the corresponding positions can be removed.
3. The application sequence of the prestress of the prestressed fish web girder tool type combined internal support is as follows: gusset (synchronous pressurization of each gusset) → fish web girder (synchronous tensioning of each fish web girder), prestressed fish web girder tool type combined internal support prestress application principle: partitioning, grading and circularly pressurizing. The construction flow of the prestressing force application is shown in fig. 3:
in the figure: A. b, C, a, b and c are steel strand tensioning.
4. The pre-tension force of the steel strand of the fish web girder is preferably 60-75% of the design value of the axial force of the steel strand, and the pre-tension axial force of the angle brace is preferably 60-70% of the design value of the axial pressure of the support.
5. The stretching, supporting and pressurizing of the steel strand are graded, the pressure is kept stable for 10min after the prestress of each grade is applied, and then the next grade is applied; after the prestress is added to the design specified value, the prestress can be locked according to the set prestress value after the prestress is kept stable for 10 min.
6. The prestress of the fish belly sill of the dismantling area must be released before the support is dismantled, and the single prestress release sequence is as follows: fish web girder→gusset. The prestress release of the demolition area follows the principle of staged cyclic release, with 4 stages (uniform) of prestress release.
In the embodiment, the steel sheet piles and the large-span fish web beam steel supports are combined into a full green foundation pit supporting structure. Providing technical support for the inner support optimization design and construction scheme of the soft soil deep foundation pit support by utilizing the assembled steel truss structure composite beam technology; the steel sheet pile assembly structure is utilized to replace a foundation pit enclosure structure formed by a traditional drilling concrete pile and a cement soil mixing pile waterproof curtain, so that the safety of foundation pit engineering, the reliability of construction quality and the rapidness of soil taking and conveying of the foundation pit and the convenience of underground structure construction are improved, meanwhile, the construction cost of the foundation pit is reduced, the construction period is shortened, and the whole recovery and reutilization of supporting members are realized.
The foregoing has shown and described the basic principles, principal features and advantages of the utility model. It will be understood by those skilled in the art that the present utility model is not limited by the foregoing examples, which are provided by way of illustration of the principles of the present utility model, and that various changes and modifications may be made therein without departing from the spirit and scope of the utility model as defined in the appended claims. The scope of the utility model is defined by the appended claims and equivalents thereof.

Claims (8)

1. The fully assembled large-span steel structure soft soil deep foundation pit supporting structure is characterized in that steel sheet piles are adopted as retaining structures for retaining soil and stopping water, a steel section standardized member is adopted to assemble and form a horizontal truss structure to serve as a horizontal support, and the horizontal support comprises a gusset and a prestress enclosing purlin; the prestress enclosing purlin and the angle brace are connected into a whole, the stress axes of the prestress enclosing purlin and the angle brace are on the same plane, and the angle brace is provided with a pressure-adjustable pressurizing device; the prestress enclosing purlin comprises a lower chord beam, a web member is arranged on the lower chord beam and extends to the inner side of a foundation pit, steel strands are arranged at the top of the web member, two ends of each steel strand are connected with two ends of the lower chord beam, and the steel strands and the lower chord beam form a closed fish belly structure; the lower chord beam is closely attached to the steel sheet pile.
2. The fully assembled large-span steel structured soft soil deep foundation pit supporting structure according to claim 1, wherein the steel sheet piles are mutually meshed Lassen steel sheet piles.
3. The fully assembled large-span steel structure soft soil deep foundation pit supporting structure according to claim 1, wherein the steel sheet piles are steel pipe piles or steel pipe and steel sheet combined piles which are connected with each other.
4. The fully assembled large-span steel structure soft soil deep foundation pit supporting structure according to claim 1, wherein the steel sheet pile is internally provided with a steel purlin, and the lower chord beam is attached to the steel purlin.
5. The fully assembled large-span steel structure soft soil deep foundation pit supporting structure according to claim 1, wherein the gusset and the prestressed enclosing purlin are connected with a cross beam, the cross beam is arranged on the upright posts, and the upright posts are connected by tie rods.
6. The fully assembled large-span steel structure soft soil deep foundation pit supporting structure of claim 5, wherein the pull rod is a section steel, a steel strand or a steel wire rope.
7. The fully assembled large-span steel structure soft soil deep foundation pit supporting structure of claim 1, wherein the pressurizing device is a self-locking oil cylinder.
8. The fully assembled large span steel structured soft soil deep foundation pit supporting structure as claimed in claim 1, wherein all steel standardized members are connected with each other by bolts.
CN202222469589.2U 2022-09-19 2022-09-19 Full-assembled large-span steel structure soft soil deep foundation pit supporting structure Active CN219527660U (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202222469589.2U CN219527660U (en) 2022-09-19 2022-09-19 Full-assembled large-span steel structure soft soil deep foundation pit supporting structure

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202222469589.2U CN219527660U (en) 2022-09-19 2022-09-19 Full-assembled large-span steel structure soft soil deep foundation pit supporting structure

Publications (1)

Publication Number Publication Date
CN219527660U true CN219527660U (en) 2023-08-15

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