CN216108526U - Underground continuous wall structure for foundation pit support - Google Patents

Abstract

The utility model discloses an underground continuous wall structure for foundation pit supporting, which comprises an underground continuous wall, a crown beam and a structure top plate, wherein the underground continuous wall comprises an upper underground continuous wall and a lower underground continuous wall which are integrally formed, the section of the upper underground continuous wall in the width direction is smaller than that of the lower underground continuous wall in the width direction, and a platform for lapping the structure top plate is formed at the section change positions of the upper underground continuous wall and the lower underground continuous wall. The utility model has the characteristics of simple structure, small construction difficulty and small engineering investment, and is suitable for the engineering with compact site conditions and short construction period.

Description

Underground continuous wall structure for foundation pit support

Technical Field

The utility model relates to the field of foundation pit excavation supporting engineering, in particular to an underground continuous wall structure for foundation pit supporting.

Background

The underground continuous wall is a commonly used supporting structure in foundation pit engineering, under the condition of slurry wall protection, a long and narrow deep groove is dug on the ground, a reinforcement cage is hung after the groove is cleaned, underwater concrete is poured by using a conduit method to form a unit groove section, and the steps are carried out section by section in this way, and a continuous reinforced concrete wall is built underground.

At present, the common method for subway station construction in China comprises the following steps: open-cut method, cover-cut method and underground method. The four construction methods have the advantages and disadvantages of the applicable conditions, and are mainly determined according to the surrounding environment, geological conditions, construction period, construction cost, construction difficulty and the like of the station.

The enclosure system of the cover-excavation reverse construction method has the advantages of high rigidity, small deformation, high safety, small interference to ground functions, easiness in pipeline relocation, capability of greatly saving the mounting and dismounting of temporary support systems and the like, and the main defects of the construction method are that the process is complex, the construction period is long, and the enclosure system is preferentially selected in areas with high requirements on environmental civilization and deformation control, such as weak strata, central blocks, commercial and luxurious areas and the like.

The underground continuous wall is used as a supporting structure for cover-excavation reverse construction, and is preferably used as a supporting structure scheme by virtue of large rigidity and good water stopping under the geological conditions of soft stratum and high confined water.

The conventional construction method for the top plate of the cover-excavation top-down structure comprises three steps:

a. slope-laying excavation

When the site condition is wide, slope excavation can be carried out within the excavation depth range of the structural top plate (reference numeral 3), so that the structural top plate is lapped on the enclosing structure crown beam (reference numeral 2) during construction of the structural top plate. The method has simple process, but has requirements on site conditions, large earth excavation backfill amount, moderate engineering investment and detailed figure 1 (a).

b. Additionally provided with an enclosure structure

When the field conditions are limited, slope releasing is not allowed, a row of drilled piles (reference number 4) can be additionally arranged on the outer side of the existing underground diaphragm wall, and a cantilever structure formed by the drilled piles keeps water and soil, so that the structural roof is lapped on the building envelope crown beam when the structural roof is constructed. The method has simple process, but needs to be additionally provided with a building envelope, and has high engineering investment, and the detailed process is shown in figure 1 (b).

c. Mortise enclosure structure

When the site condition is limited and the drilled pile is not allowed to be arranged, a certain range can be chiseled out from the inner side of the underground continuous wall within the height range of the structural top plate, so that the structural top plate is embedded and fixed on the underground continuous wall during the construction of the structural top plate, and a tongue-and-groove (reference number 5) structure is formed. The method has the advantages of complex process, high construction difficulty and small engineering investment, and is shown in figure 1 (c).

Therefore, it is necessary to research an underground diaphragm wall structure with simple process, small construction difficulty and small engineering investment.

SUMMERY OF THE UTILITY MODEL

Aiming at the defects in the prior art, the utility model aims to provide an underground continuous wall structure for foundation pit supporting. The section of the underground continuous wall is small at the top and large at the bottom, and the structural top plate of the reverse construction method is covered and dug at the change position of the section, so that the 'one-wall dual-purpose' of the underground continuous wall is achieved, and the underground continuous wall is used as a horizontal soil retaining structure and a vertical top plate bearing structure, has the characteristics of simple process, small construction difficulty and small engineering investment, and is suitable for engineering with compact site conditions and short construction period.

In order to solve the technical problems, the utility model is realized by the following technical scheme:

the utility model provides an underground continuous wall structure for excavation supporting, includes underground continuous wall, crown beam and structure roof, underground continuous wall includes integrated into one piece's upper portion underground continuous wall and lower part underground continuous wall, the cross-section of upper portion underground continuous wall width direction is less than the cross-section of lower part underground continuous wall width direction, just the cross-section change department of upper portion underground continuous wall and lower part underground continuous wall forms and supplies the overlap joint the platform of structure roof.

Preferably, the upper underground continuous wall is internally added with construction steel bars fixedly connected with the steel bar cage of the underground continuous wall. In order to meet the structural requirements of the upper underground continuous wall structure during the construction of the underground continuous wall crown beam, the structural steel bars are additionally arranged on the steel bar cage section corresponding to the foam board because the thickness of the variable cross-section at the upper part of the underground continuous wall is thinned, so that the integral stability and the rigidity requirements of the upper underground continuous wall structure are ensured.

It is further preferred that the construction steel bars comprise vertical reinforcing steel bars and horizontal reinforcing steel bars which are close to one side of the foundation pit and fixedly connected together. The constructional steel bar is close to cystosepiment one side setting, can regard as the foundation structure of ligature cystosepiment, further reduces and pours the influence of in-process cystosepiment come-up to steel reinforcement cage structural stability at underground continuous wall. The vertical reinforcing steel bars and the horizontal reinforcing steel bars are welded together in a crossed manner, so that the integral stability and rigidity requirements of the upper underground continuous wall structure can be met.

Preferably, a crown beam is interposed between the structural roof and a section change of the upper and lower underground continuous walls. The crown beam is poured at the section change position of the underground continuous wall, so that the structural stability of the structural top plate and the section change position of the underground continuous wall can be further enhanced.

Preferably, the upper underground continuous wall is filled with a foam board in a top width direction. The requirement that the top of the underground continuous wall needs to be provided with a groove to pass through a drainage pipeline can be met, and the reinforced concrete structure is prevented from being broken in the later period of manpower.

Compared with the prior art, the utility model has the following advantages and beneficial effects:

the utility model adopts the underground continuous wall with the section of the upper underground continuous wall smaller than that of the lower underground continuous wall, the underground continuous wall is used for preventing soil outside the foundation pit from entering the foundation pit, and the structure top plate is directly erected at the section change part of the underground continuous wall, so that the underground continuous wall has two purposes of one wall and two purposes, namely serving as a horizontal soil retaining structure and a bearing structure of the vertical structure top plate.

The utility model can fill the foam board in the width direction of the top of the underground continuous wall, can meet the requirement that the top of the underground continuous wall needs to be provided with the groove to pass through the drainage pipeline, and avoids breaking the reinforced concrete structure in the later period of manpower.

Drawings

FIG. 1 is a schematic diagram of a conventional cover-excavation top-down construction in the background art, wherein (a) is a slope-making excavation structure, (b) is an additional enclosure, and (c) is a mortise enclosure;

FIG. 2 is a schematic diagram of an exemplary cross-sectional configuration of the present invention;

FIG. 3 is a schematic structural view of the underground diaphragm wall with the foam board of the present invention;

FIG. 4 is a sectional view taken along line A-A of FIG. 3;

FIG. 5 is a cross-sectional view taken along line B-B of FIG. 3;

FIG. 6 is a cross-sectional view taken along line C-C of FIG. 3;

FIG. 7 is a floor plan of the underground diaphragm wall and pipeline of the present invention;

FIG. 8 is a schematic view of the construction of the underground diaphragm wall and pipeline of the present invention in elevation.

Reference numerals: 1-underground diaphragm wall; 11-a reinforcement cage; 12-upper underground diaphragm wall; 13-lower underground diaphragm wall; 14-a platform; 2-a crown beam; 3-a structural ceiling; 4-drilling a pile; 5-mortising; 6-foam board; 7-constructing a steel bar; 71-vertical reinforcing steel bars; 72-horizontal reinforcing steel bars; 8-a catheter; 9-pipeline.

Detailed Description

In order that those skilled in the art will better understand the technical solutions of the present invention, the following description of the preferred embodiments of the present invention is provided in conjunction with specific examples, but it should be understood that the drawings are for illustrative purposes only and should not be construed as limiting the patent; for the purpose of better illustrating the embodiments, certain features of the drawings may be omitted, enlarged or reduced, and do not represent the size of an actual product; it will be understood by those skilled in the art that certain well-known structures in the drawings and descriptions thereof may be omitted. The positional relationships depicted in the drawings are for illustrative purposes only and are not to be construed as limiting the present patent.

The present invention will be further described with reference to the following examples and figures 2-8, but the utility model is not limited thereto.

As shown in fig. 2, the present embodiment provides an underground continuous wall structure for supporting a foundation pit, which includes an underground continuous wall 1, a crown beam 2 and a structure roof 3, wherein the underground continuous wall 1 includes an upper underground continuous wall 12 and a lower underground continuous wall 13 which are integrally formed, a section of the upper underground continuous wall 12 in a width direction is smaller than a section of the lower underground continuous wall 13 in the width direction, and a platform 14 for overlapping the structure roof 3 is formed at a change of the sections of the upper underground continuous wall 12 and the lower underground continuous wall 13.

Based on the structure, the embodiment also provides a construction method of the underground continuous wall structure for foundation pit supporting, which comprises the following steps:

firstly: and (4) conducting guide wall construction, trenching and excavating, slurry wall protection and cleaning holes at the bottom of the groove in sequence according to construction requirements to obtain the constructed groove holes.

The grooving technical parameters of the underground continuous wall are as follows:

1) in the excavation process of the groove section of the underground continuous wall 1, the groove is always filled with slurry to keep the groove wall stable; 2) the stability of the groove section excavation is enhanced, if the groove wall is seriously locally collapsed, the groove section excavation is backfilled in time and properly processed; 3) during construction, slurry leakage should be timely supplemented, and the required liquid level height is always kept. The quality of the slurry is checked regularly, and the index of the slurry is adjusted in time; 4) after the groove section is excavated, the groove position, the groove depth, the groove width and the groove wall verticality are checked, and the groove cleaning and slurry changing work can be carried out after the groove section is qualified; 5) the control of the final groove depth of the groove section meets the following requirements: a. the final groove depth of the groove section must ensure the design depth, and in the same groove section, the excavation depth of the groove bottom is consistent and kept flat; b. the excavation depth of the groove bottom of the underground continuous wall 1 of the extension section in the same groove section is consistent with that of the groove bottom of the first-stage groove section; 6) the length, thickness, inclination, etc. of the groove sections should meet the following requirements: a. the allowable deviation of the length of the groove section is +/-2.0 percent; b. the allowable deviation of the thickness of the groove section is +/-10 mm; c. the allowable deviation of the perpendicularity of the groove section is +/-1/300; d. the local projection of the wall surface is not more than 100 mm; e. the position deviation of the embedded part on the wall surface is not more than 100 mm; f. deviation of the center line of the wall top: less than or equal to 30 mm; g. the areas of the holes, exposed ribs and honeycombs are not more than 5% of the exposed area of the unit groove section; h. the joint of the groove sections has no mud inclusion and no water leakage; 7) and cleaning impurities such as sediments at the bottom of the tank after the tank digging is finished, wherein the specific gravity of the slurry within 500mm of the bottom of the tank is not more than 1.15 and the thickness of the sediments is not more than 100mm after the tank bottom is cleaned and the slurry is replaced for 1 hour.

Secondly, the method comprises the following steps: the foam plate 6 is fixedly arranged on the section of the reinforcement cage 11 corresponding to the upper underground continuous wall 12, so that the section of the reinforcement cage 11 with the foam plate 6 is uniform in size in the width direction, as shown in fig. 3 to 6.

The arrangement range of the foam plate 6 is from the top of the reinforcement cage 11 close to the foundation pit direction to the section change position of the reinforcement cage 11. The foam plates 6 are spliced into blocks and bound on the reinforcement cage 11 by adopting iron wires. Because the density of the foam board 6 is small, the foam board 6 needs to be firmly bound to prevent the foam board 6 from floating upwards in the process of placing the reinforcement cage 11 downwards and pouring underwater concrete. The foam board 6 is directly stripped from the underground continuous wall 1 in a manual breaking mode during foundation pit excavation.

The steel reinforcement cage is manufactured as follows:

1) in order to meet the structural requirements of the upper underground continuous wall 12 structure when the underground continuous wall 1 crown beam 2 is constructed. And a construction steel bar 7 is additionally arranged on the section of the steel bar cage 11 corresponding to the foam board 6, the construction steel bar 7 comprises a vertical reinforcing steel bar 71 and a horizontal reinforcing steel bar 72 which are adjacent to one side of the foam board 6, and the vertical reinforcing steel bar 71 and the horizontal reinforcing steel bar 72 are welded together.

2) The main reinforcement of the reinforcement cage 11 should be welded or mechanically connected, the number of joints in the same connection section should not be greater than 50%, and the joints should be placed at positions with small stress as much as possible. The intersection points of the longitudinal and transverse steel bar trusses and the steel bar cage 11 are all spot-welded, and the intersection points of the main bars and the distribution bars can be spot-welded at intervals. The reinforcement cages 11 of the unit groove sections of the underground continuous wall 1 are preferably assembled into a whole; when the segments are required to be segmented, mechanical connection is adopted, and joints are staggered with each other.

3) In order to ensure the thickness of the steel bar protection layer, positioning blocks are welded on two sides of the steel bar cage 11, two rows are arranged on each side of the steel bar cage 11 in the width direction, and the longitudinal distance between every two positioning blocks is 4 m.

And furthermore: and (3) lowering the reinforcement cage 11 with the foam plates 6 into the slotted hole, then placing the guide pipe 8 into the reinforcement cage 11, and injecting concrete into the slotted hole along the guide pipe 8 until the underground continuous wall 1 with the variable cross section is formed. In order to smoothly pour the underwater concrete, the arrangement of the guide pipe 8 needs to be adjusted to the middle of the variable cross section of the underground continuous wall 1, as shown in fig. 4.

Hoisting and embedding embedded parts of the steel reinforcement cage 11:

1) when the steel reinforcement cage 11 is put into the groove to the designed elevation, the channel steel penetrates into the suspension loop at the upper end of the vertical truss of the steel reinforcement cage 11 and is placed on the guide wall.

2) The manufacturing and hoisting deviation control requirements of the reinforcement cage 11 are as follows:

the distance deviation of the vertical main ribs is not more than 10mm, and the distance deviation of the horizontal main ribs is not more than 20 mm; the position deviation of the embedded part is not more than 10 mm; the central position of the steel reinforcement cage 11 hung in the groove is not more than 10 mm; the verticality of the steel reinforcement cage 11 in the hanging groove is not more than 2 per thousand; the elevation deviation of the steel reinforcement cage 11 in the hanging groove is not more than 10 mm.

Pouring concrete:

1) the diameter, the distance and the position of the concrete guide pipes 8 are staggered with respect to the plane of the foam plate 6.

2) The mixing proportion of the concrete meets the design strength requirement, and the concrete poured in the slurry by adopting the guide pipe 8 has good workability, large fluidity and delayed coagulation; the density difference between the concrete and the slurry is more than 1.1.

3) Before concrete pouring, the conduit 8 can be used for circulating the slurry for more than 15min so as to improve the quality of the slurry in the groove.

4) The concrete should begin to pour in the 11 inslots of steel reinforcement cage 6h, and speed will be fast when just beginning to pour, makes the tank bottom sediment rise along with the concrete surface together, treats when the top standard height of concrete closes on cystosepiment 6, should pour slowly to ensure that cystosepiment 6 bottom concrete placement is closely knit, and prevent that the rising of concrete under water from influencing cystosepiment 6's fixed.

In addition, the foam board 6 can be filled in the width direction of the top of the reinforcement cage 11, so that the requirement that a groove needs to be arranged at the top of the underground continuous wall 1 to penetrate through the drainage pipeline 9 can be met, and the reinforced concrete structure is prevented from being broken in a later period manually, as shown in fig. 7 and 8.

And finally: and excavating a foundation pit to the section change position of the underground continuous wall 1, synchronously removing the foam plate 6, then pouring the top beam 2 on the top of the underground continuous wall 1 and the section change position, and then pouring the structural top plate 3 on the top beam 2 at the section change position until the construction is finished. During the excavation of the foundation pit, the foam board 6 is directly stripped from the underground continuous wall 1 in a manual breaking mode, and the variable cross section of the underground continuous wall 1 forms a retaining structure, as shown in fig. 2.

The variable cross section at the upper part of the underground continuous wall 1 adopts a foam filling mode, when underwater concrete is poured, the variable cross section can be formed at the upper part of the underground continuous wall 1, and a structural top plate 3 of a reinforced concrete crown beam and a cover-excavation reverse method can be arranged at the change part of the cross section, so that the aim of 'one wall and two purposes' is fulfilled, and the independent additional arrangement of supporting structures such as a drilling pile 4, a steel sheet pile and the like outside the underground continuous wall 1 is avoided.

According to the description of the utility model and the accompanying drawings, those skilled in the art can easily manufacture or use the underground continuous wall structure for supporting the foundation pit, and can produce the positive effects recorded in the utility model.

Unless otherwise specified, in the present invention, if there is an orientation or positional relationship indicated by terms of "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., based on the orientation or positional relationship shown in the drawings, it is only for convenience of describing the present invention and simplifying the description, rather than to indicate or imply that the device or element so referred to must have a particular orientation, be constructed and operated in a particular orientation, therefore, the terms describing orientation or positional relationship in the present invention are for illustrative purposes only, and should not be construed as limiting the present patent, specific meanings of the above terms can be understood by those of ordinary skill in the art in light of the specific circumstances in conjunction with the accompanying drawings. Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated.

Unless expressly stated or limited otherwise, the terms "disposed," "connected," and "connected" are used broadly and encompass, for example, being fixedly connected, detachably connected, or integrally connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

The above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention in any way, and all simple modifications and equivalent variations of the above embodiments according to the technical spirit of the present invention are included in the scope of the present invention.

Claims (5)

1. The utility model provides an underground continuous wall structure for excavation supporting, includes underground continuous wall (1), crown beam (2) and structure roof (3), its characterized in that: the underground continuous wall (1) comprises an upper underground continuous wall (12) and a lower underground continuous wall (13) which are integrally formed, the section of the upper underground continuous wall (12) in the width direction is smaller than that of the lower underground continuous wall (13), and a platform (14) for overlapping the structural roof (3) is formed at the change position of the sections of the upper underground continuous wall (12) and the lower underground continuous wall (13).

2. An underground diaphragm wall structure for supporting a foundation pit according to claim 1, wherein: and structural steel bars (7) fixedly connected with the steel bar cage (11) of the underground continuous wall (1) are additionally arranged in the upper underground continuous wall (12).

3. An underground diaphragm wall structure for supporting a foundation pit according to claim 2, wherein: the construction steel bars (7) comprise vertical reinforcing steel bars (71) and horizontal reinforcing steel bars (72) which are close to one side of the foundation pit, and the vertical reinforcing steel bars (71) and the horizontal reinforcing steel bars (72) are fixedly connected together.

4. An underground diaphragm wall structure for supporting a foundation pit according to claim 1, wherein: and a crown beam (2) is clamped between the section change positions of the upper underground continuous wall (12) and the lower underground continuous wall (13) and the structural top plate (3).

5. An underground diaphragm wall structure for supporting a foundation pit according to claim 1, wherein: the top width direction of the upper underground continuous wall (12) is filled with a foam board (6).

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