CN116289979A - Deep foundation pit supporting construction method for underground forward and reverse synchronous construction - Google Patents
Deep foundation pit supporting construction method for underground forward and reverse synchronous construction Download PDFInfo
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- CN116289979A CN116289979A CN202310189215.1A CN202310189215A CN116289979A CN 116289979 A CN116289979 A CN 116289979A CN 202310189215 A CN202310189215 A CN 202310189215A CN 116289979 A CN116289979 A CN 116289979A
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Abstract
The deep foundation pit supporting construction method for underground forward and backward synchronous construction aims at solving the problems that when a basement top plate and the ground are not located on the same horizontal plane, transverse supports are required to be arranged in a foundation pit for reinforcing supporting, and construction efficiency is reduced. The method comprises the following steps: firstly constructing a central island region by adopting forward construction method, carrying out slope-placing excavation on soil mass of the central island region to the lower part of the elevation of the second structural beam slab of the basement, and pouring the central part of the second structural beam slab of the basement; a plurality of inclined throwing supports are arranged and fixedly connected between the top pressure beam and a second structural beam plate of the basement at intervals; and excavating the peripheral area of the foundation pit, pouring and constructing a second structural beam slab of the basement, dismantling the inclined throwing support after the second structural beam slab of the basement reaches the required strength, constructing a first layer of underground structure and each layer of overground structure by adopting a forward method, synchronously excavating soil below the second structural beam slab of the basement, and constructing each layer of underground structure by adopting a reverse method in sequence.
Description
Technical Field
The invention relates to the technical field of geotechnical engineering foundation pit support, in particular to a deep foundation pit support construction method for underground forward and reverse synchronous construction.
Background
In recent years, with the acceleration of the urban process, the development and utilization degree of underground space is continuously increased, the depth of a foundation pit is deeper and deeper, and the construction space of a supporting structure is also more limited. The forward construction method has the advantages of simple operation, high speed, low cost, simple supporting framework, easy mastering of construction period and easy control of engineering quality, but larger damage to surrounding environment; the reverse construction method is to take beams, plates and columns of the underground main body structure as transverse supports of the retaining wall, so that the construction period can be greatly shortened, the earthwork quantity is reduced, the construction safety is improved, but the concrete joint quality of the wall columns in the underground structure is difficult to control.
At present, in the building engineering of forward and reverse synchronous construction, a basement roof is usually used as a first support, each layer of structure is constructed on the ground by adopting forward construction method above the basement roof, each layer of structure is constructed below the basement roof by adopting reverse construction method, however, when the basement roof and the ground are not positioned on the same horizontal plane, the basement roof cannot be used as an enclosure structure to provide support, the deformation of the enclosure structure is increased due to overlong cantilever in the excavation process of a foundation pit, and transverse support reinforcing support is required to be arranged in the foundation pit in a large area, so that the construction efficiency is reduced, and the engineering cost is increased.
Disclosure of Invention
When the top plate of the basement is not positioned on the same horizontal plane with the ground, the transverse support is required to be arranged in the foundation pit in a large area for reinforcing support, so that the construction efficiency is reduced, and the engineering cost is increased. The invention aims to provide a deep foundation pit supporting construction method for underground forward and reverse synchronous construction.
The technical scheme adopted for solving the technical problems is as follows: the deep foundation pit supporting construction method for underground forward and reverse synchronous construction comprises the following steps:
s1: constructing a foundation pit enclosure structure, wherein vertical column piles and lattice piles which are vertically connected are adopted in a foundation pit as vertical supports, a layer of soil body in the ground is divided into a central island area and a peripheral area enclosed on the outer side of the central island area, the soil body in the central island area is excavated to the lower part of the elevation of a second structural beam slab of the basement in a forward construction method in advance, the central part of the second structural beam slab of the basement is poured, and part of the lattice piles which influence the construction of the second structural beam slab and the structural columns of the basement are cut off, so that the top of the lattice piles are positioned at the bottom of the second structural beam slab of the basement;
s2: a plurality of inclined throwing supports are arranged at intervals between the top beam and the central part of a second structural beam plate of the basement, and partial lattice piles influencing the arrangement of the inclined throwing supports are cut off;
s3: and excavating a soil slope in the peripheral area of the foundation pit, continuing pouring and constructing a second structural beam slab of the basement, dismantling the inclined throwing support after the second structural beam slab of the basement reaches the strength required by design, constructing a layer of underground structure and all layers of above-ground structure by adopting a forward method, synchronously excavating soil below the second structural beam slab of the basement, and constructing all layers of underground structure in sequence by adopting a reverse method.
Firstly, dividing a layer of soil body in the underground of a foundation pit into a central island area and a peripheral area, adopting forward construction method to construct the central island area in advance, sloping to excavate the layer of soil body in the underground and pour the central part of a beam slab of a second structure of the basement, installing oblique throwing support between a capping beam and the beam slab of the second structure of the basement, then, excavating the peripheral area of the foundation pit to reserve a soil slope and finish pouring construction of the beam slab of the second structure of the basement, and after the beam slab of the second structure of the basement reaches the strength required by design, dismantling the oblique throwing support and adopting forward construction method to construct the layer of the underground and structures at the upper part of the layer of the second structure of the underground, synchronously excavating the soil body below the beam slab of the second structure of the basement and adopting reverse construction method to construct structures at the lower layers of the underground in sequence; the deep foundation pit supporting construction method for underground forward and reverse synchronous construction has the following beneficial effects:
1. the construction method is characterized in that a central island area is constructed in advance, the central part of a second structural beam plate of the basement is poured, and an inclined throwing support is additionally arranged between a top beam and the second structural beam plate of the basement, so that a support structure, the inclined throwing support, lattice piles and part of main body structures are mutually connected to form a complete support structure stress system so as to resist the surrounding water and soil pressure, construction load and the like, the support structure in the foundation pit is simplified, the construction efficiency is improved, the construction period is shortened, the adverse factors of long construction period, environmental pollution and the like caused by the erection and dismantling of the horizontal support in the conventional forward construction are avoided, the engineering cost is effectively saved, and the green construction is realized;
2. the second structural beam plate of the basement is used as the first horizontal support of the reverse construction method, namely, the forward and reverse combined up and down synchronous construction is carried out under the ground, so that the number of layers of the reverse construction is reduced, the construction difficulty is reduced, the time for waiting for the structural beam plate to reach the design strength is shortened, the construction efficiency is accelerated, and the engineering cost is reduced;
3. in order to meet the requirement of the vertical bearing capacity of one column and one pile, the cross section size of the lattice pile is often larger than that of the basement structural pile, so that the structural pile cannot be wrapped by the structural pile.
Preferably, in the step S1, the construction method of the foundation pit support structure is as follows: the two sides of the groove section where the underground diaphragm wall is positioned are provided with triaxial cement mixing piles for groove wall reinforcement, water is stopped at the joint of the underground diaphragm wall through large-diameter high-pressure jet grouting piles, an L-shaped integrally-poured concrete guide wall is formed at the top of the triaxial cement mixing piles located on the outer side, one end of the concrete guide wall is arranged on the inner side of the triaxial cement mixing piles, the other end of the concrete guide wall is located at the top of the triaxial cement mixing piles, a capping beam is constructed at the top of the underground diaphragm wall, and reserved main ribs are arranged.
Preferably, in the step S1, the peripheral area of the soil body of the underground layer of the foundation pit is excavated in a manner that the width of the slope-laying platform is not less than 3m and the slope-laying gradient is not greater than 1:1.5, a concrete panel is laid on the slope, a reinforcing mesh is arranged in the concrete panel, and anchor bars and dowel bars are arranged in the concrete panel to protect the slope.
Preferably, the concrete support is fixedly connected to the joint between the top of the edge of the central part of the second structural beam plate of the basement and the structural column, the steel support is riveted on the side surface of the top beam, one end of the inclined throwing support is welded on the steel support, and the other end of the inclined throwing support is riveted on the concrete support through an anchor plate.
Preferably, a reserved main rib is arranged at a construction joint at the end part of the central part of the second structural beam slab of the basement, and the reserved main rib is connected with a structural main rib of the second structural beam slab of the peripheral area of the later construction.
Drawings
FIG. 1 is a schematic diagram of sequential excavation of a center island region in an embodiment of a deep foundation pit supporting construction method for underground sequential synchronous construction of the present invention;
fig. 2 is a schematic diagram of a deep foundation pit supporting construction method for underground forward and reverse synchronous construction in which a diagonal throwing support is arranged between a first structural beam plate and a top beam of a basement in an embodiment of the invention.
Fig. 3 is a schematic diagram of forward and reverse synchronous construction of an embodiment of a deep foundation pit supporting construction method for underground forward and reverse synchronous construction of the present invention.
The labels in the figures are as follows:
a column pile 1; lattice piles 2; a concrete panel 3; a dowel bar 4; anchor bars 5; a diaphragm wall 11; a triaxial cement-soil mixing pile 12; high pressure jet grouting piles 14; a concrete guide wall 15; a capping beam 16; reserving a main rib 17; a basement first structural beam plate 21; a second structural beam plate 22 of the basement; a structural column 25; a concrete support 26; a steel support 27; and a diagonal slinging support 28.
Detailed Description
The invention is described in further detail below with reference to the drawings and the specific examples. It should be noted that the drawings are in a very simplified form and are all to a non-precise scale, merely for convenience and clarity in aiding in the description of embodiments of the invention. For convenience of description, the "upper" and "lower" described below are consistent with the upper and lower directions of the drawings, but this should not be construed as a limitation of the technical scheme of the present invention.
In this embodiment, the basement top plate (i.e. the basement first structural beam plate 21) is located above the leveling ground, and the following specific steps are as follows, in which the deep foundation pit supporting construction method for underground forward and reverse synchronous construction of the present invention is described with reference to fig. 1 to 3:
s1: as shown in fig. 1, constructing a foundation pit enclosure structure, wherein vertical column piles 1 and lattice piles 2 (i.e. one column and one pile) which are vertically connected are adopted as vertical supports in a foundation pit, a layer of soil body in the ground is divided into a central island area and a peripheral area enclosed outside the central island area, the central island area is constructed in advance by adopting forward construction, a dot-dash line marking area in fig. 1 is a central island area, the soil body in the central island area is excavated to the position below the elevation of a second structural beam slab 22 of the basement, the central part of the second structural beam slab 22 of the basement is poured, as shown in fig. 2, part of the lattice piles 2 which influence the construction of the second structural beam slab 22 and the structural columns 25 of the basement, namely part of the lattice piles 2 which are filled by dotted line frame lines and oblique lines in fig. 2, is cut off, so that the top of the lattice piles 2 are positioned at the bottom of the second structural beam slab 22 of the basement;
s2: as shown in fig. 2, a plurality of diagonal throws 28 are arranged at intervals between the top beam 16 and the central part of the second structural beam plate 22 of the basement, and part of lattice piles 2 influencing the arrangement of the diagonal throws 28 are cut off;
s3: as shown in fig. 3, the soil slope is reserved in the peripheral area of the foundation pit, the second-channel structural beam slab 22 of the basement is continuously poured and constructed, after the second-channel structural beam slab 22 of the basement reaches the strength required by design, the diagonal cast support 28 is removed, the first-layer structure and the upper-layer structures of the first-layer structure are constructed by adopting a forward method, soil below the second-channel structural beam slab 22 of the basement is synchronously excavated, and the underground structures such as the second-layer structure, the third-layer structure and the like are sequentially constructed by adopting a reverse method.
Firstly, dividing a layer of soil body in the underground of a foundation pit into a central island area and a peripheral area, adopting forward construction method to construct the central island area in advance, sloping to excavate the layer of soil body in the underground and pour the central part of a second structural beam slab 22 of the basement, installing a diagonal cast support 28 between a top beam 16 and the second structural beam slab 22 of the basement, then, excavating the peripheral area of the foundation pit to reserve soil slopes and finish the pouring construction of the beam slab 22 of the second structural beam slab of the basement, removing the diagonal cast support 28 and adopting forward construction method to construct the layer of the underground and each layer of structure above the layer of the underground after the beam slab 22 of the second structural beam slab of the basement reaches the strength required by design, and synchronously excavating the soil body below the beam slab 22 of the second structural beam slab of the basement and adopting reverse construction method to construct each layer of structures of the underground in sequence; the deep foundation pit supporting construction method for underground forward and reverse synchronous construction has the following beneficial effects:
1. unlike the prior reverse construction method, which uses the first structural beam plate 21 of the basement as the first horizontal support, the construction method firstly constructs the central island region and pours the central part of the second structural beam plate 22 of the basement, and adds the inclined support 28 between the top beam 16 and the second structural beam plate 22 of the basement, so that the enclosure structure, the inclined support 28, the lattice piles 2 and part of the main body structure are mutually connected to form a complete support structure stress system so as to resist the peripheral water and soil pressure, construction load and the like, the support framework in the foundation pit is simplified, the construction efficiency is improved, the construction period is shortened, the adverse factors of long construction period, environmental pollution and the like caused by the erection and dismantling of the horizontal support in the conventional construction method are avoided, and the inclined support 28 can be removed, recycled and reused in the later period, so that the construction cost is effectively saved, and the green construction is realized;
2. because the second structural beam plate 22 of the basement is used as the first horizontal support of the reverse construction method, namely, the forward and reverse combined up and down synchronous construction is carried out under the ground, the number of layers of the reverse construction is reduced, the construction difficulty is reduced, the time for waiting for the structural beam plate to reach the design strength is shortened, the construction efficiency is accelerated, and the engineering cost is reduced;
3. in order to meet the requirement of the vertical bearing capacity of one column and one pile, the cross section size of the lattice pile 2 is often larger than that of the basement structural column 25, so that the structural column 25 cannot wrap the lattice pile 2.
As shown in fig. 1, the construction method of the foundation pit support structure in this embodiment includes the following steps: triaxial cement-soil stirring piles 12 are arranged on two sides of a groove section where the underground diaphragm wall 11 is positioned for groove wall reinforcement so as to ensure the groove forming safety of the underground diaphragm wall 11, and water is stopped at the joint of the underground diaphragm wall 11 through RJP large-diameter high-pressure jet grouting piles 14; an L-shaped integrally-poured concrete guide wall 15 is formed at the top of the triaxial cement mixing pile 12 positioned at the outer side, one end of the concrete guide wall 15 is arranged at the inner side of the triaxial cement mixing pile 12, the other end of the concrete guide wall 15 is positioned at the top of the triaxial cement mixing pile 12, a capping beam 16 is constructed at the top of the underground diaphragm wall 11, and a main rib 17 is reserved so as to be connected with a main rib of an outer wall of a basement which is constructed later.
With continued reference to fig. 1, a layer of soil body under the foundation pit is excavated in a manner that the width of a slope-placing platform is more than or equal to 3m, the slope-placing gradient is not more than 1:1.5, a C20 concrete panel 3 with the thickness of 80mm is paved on the slope, a 6.5@200x200 reinforcing steel bar net (not shown in the figure) is arranged in the concrete panel 3, and phi 48 multiplied by 3.5 anchor bars 5 and phi 20 dowel bars 4 are arranged in the concrete panel 3 for slope protection.
As shown in fig. 2, the concrete support 26 is fixedly connected to the junction between the top of the central portion edge of the second structural beam plate 22 of the basement and the structural column 25, the steel support 27 is riveted to the side of the top beam 16, one end of the diagonal cast support 28 is welded to the steel support 27, and the other end is riveted to the concrete support 26 through an anchor plate.
And a main rib 17 is reserved at the end construction joint of the central part of the second structural beam slab 22 of the basement, so that the second structural beam slab is conveniently connected with the main structural rib of the second structural beam slab of the peripheral area of the later construction.
And a construction operation space with the construction joint distance of more than or equal to 1m from the slope bottom is reserved on the second-channel structural beam plate 22 of the basement.
The above description is only illustrative of the preferred embodiments of the present invention and is not intended to limit the scope of the present invention, and any alterations and modifications made by those skilled in the art based on the above disclosure are intended to fall within the scope of the claims.
Claims (5)
1. The deep foundation pit supporting construction method for underground forward and reverse synchronous construction is characterized by comprising the following steps:
s1: constructing a foundation pit enclosure structure, wherein vertical column piles and lattice piles which are vertically connected are adopted in a foundation pit as vertical supports, a layer of soil body in the ground is divided into a central island area and a peripheral area enclosed on the outer side of the central island area, the soil body in the central island area is excavated to the lower part of the elevation of a second structural beam slab of the basement in a forward construction method in advance, the central part of the second structural beam slab of the basement is poured, and part of the lattice piles which influence the construction of the second structural beam slab and the structural columns of the basement are cut off, so that the top of the lattice piles are positioned at the bottom of the second structural beam slab of the basement;
s2: a plurality of inclined throwing supports are arranged at intervals between the top beam and the central part of a second structural beam plate of the basement, and partial lattice piles influencing the arrangement of the inclined throwing supports are cut off;
s3: and excavating a soil slope in the peripheral area of the foundation pit, continuing pouring and constructing a second structural beam slab of the basement, dismantling the inclined throwing support after the second structural beam slab of the basement reaches the strength required by design, constructing a layer of underground structure and all layers of above-ground structure by adopting a forward method, synchronously excavating soil below the second structural beam slab of the basement, and constructing all layers of underground structure in sequence by adopting a reverse method.
2. The deep foundation pit supporting construction method for simultaneous underground forward and reverse construction according to claim 1, wherein in the step S1, the construction method of the foundation pit supporting structure is as follows: the two sides of the groove section where the underground diaphragm wall is positioned are provided with triaxial cement mixing piles for groove wall reinforcement, water is stopped at the joint of the underground diaphragm wall through large-diameter high-pressure jet grouting piles, an L-shaped integrally-poured concrete guide wall is formed at the top of the triaxial cement mixing piles located on the outer side, one end of the concrete guide wall is arranged on the inner side of the triaxial cement mixing piles, the other end of the concrete guide wall is located at the top of the triaxial cement mixing piles, a capping beam is constructed at the top of the underground diaphragm wall, and reserved main ribs are arranged.
3. The deep foundation pit supporting construction method for underground forward and reverse synchronous construction according to claim 1, wherein the method comprises the following steps: in the step S1, the peripheral area of a layer of soil body under the foundation pit is excavated in a mode that the width of a slope-placing platform is more than or equal to 3m, the slope-placing gradient is not more than 1:1.5, a concrete panel is paved on the slope, a reinforcing steel bar net is arranged in the concrete panel, and anchor bars and dowel bars are arranged in the concrete panel to protect the slope.
4. The deep foundation pit supporting construction method for underground forward and reverse synchronous construction according to claim 1, wherein the method comprises the following steps: the concrete support is fixedly connected to the joint part between the top of the edge of the central part of the second structural beam slab of the basement and the structural column, the steel support is riveted on the side surface of the top beam, one end of the inclined throwing support is welded on the steel support, and the other end of the inclined throwing support is riveted on the concrete support through an anchor plate.
5. The deep foundation pit supporting construction method for underground forward and reverse synchronous construction according to claim 1, wherein the method comprises the following steps: and a reserved main rib is arranged at the end construction joint of the central part of the second structural beam slab of the basement and is connected with the structural main rib of the second structural beam slab of the peripheral area of the later construction.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117248539A (en) * | 2023-11-17 | 2023-12-19 | 上海建工一建集团有限公司 | Co-construction reverse excavation supporting structure for subway cross soft soil oversized foundation pit and construction method |
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2023
- 2023-03-02 CN CN202310189215.1A patent/CN116289979A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117248539A (en) * | 2023-11-17 | 2023-12-19 | 上海建工一建集团有限公司 | Co-construction reverse excavation supporting structure for subway cross soft soil oversized foundation pit and construction method |
| CN117248539B (en) * | 2023-11-17 | 2024-02-06 | 上海建工一建集团有限公司 | Co-construction reverse excavation supporting structure for subway cross soft soil oversized foundation pit and construction method |
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