Foundation pit support structure and construction method thereof

Abstract

The invention discloses a foundation pit support structure and a construction method thereof.The foundation pit support structure comprises a row of cast-in-place piles, the row of cast-in-place piles are a row of cast-in-place bored piles which are arranged on the edge of a foundation pit and evenly distributed, additional row piles are arranged on the sides, relatively away from the foundation pit, of the cast-in-place piles, and a certain distance is formed between the additional row piles and the cast-in-place piles; the additional row piles are a row of piles which are uniformly arranged, the pile distance between the additional row piles is smaller than the pile distance between the cast-in-place piles, capping beams are fixedly mounted at the tops of the cast-in-place piles and the tops of the additional row piles, and the two capping beams are fixedly connected through a connecting beam. And connection is carried out through the coping beams, the connecting beams and the reinforcing plates, so that the integrity is improved, additional arrangement of profile steel inclined struts is not needed, the construction cost is reduced, meanwhile, the risk that the foundation pit bottom plate leaks due to retention of the profile steel inclined struts is reduced, and high popularization value is achieved.

Description

Technical Field

[0001] This invention relates to the field of building construction technology, and in particular to a foundation pit retaining structure and its construction method. Background Technology

[0002] Please see Figure 1 and Figure 2 As shown, the foundation pit retaining structure of a certain project adopts a combination of a single row of cast-in-place piles 1 (900mm in diameter, 1400mm in spacing, and 15m in length) and steel diagonal bracing 2 (H-beams, 400mm in height * 400mm in width * 13mm in web thickness * 21mm in flange thickness, Q355B). A water-stop curtain 3 (made of high-pressure jet grouting piles with a diameter of 800mm and a spacing of 600mm, interlocked) is installed on the outside of the cast-in-place pile row 1 for water prevention. A ring beam 4 is installed on the top of the cast-in-place pile row 1. On one side of the cast-in-place pile row 1, below the base slab 5, a temporary inclined support pile cap 6 (square, 4000mm long * 4000mm wide * 800mm thick) needs to be installed at a certain distance from the cast-in-place pile row 1. Steel inclined braces 2 connect the ring beam 4 on the top of the cast-in-place pile row 1 and the inclined support pile cap 6. Two steel inclined braces 2 are installed on each inclined support pile cap 6. However, the above-mentioned enclosure method has the following drawbacks during construction:

[0003] 1) Temporary inclined support pile caps 6 need to be added for the steel inclined bracing 2. Four cast-in-place piles 7 (diameter 800mm, pile length 9m) need to be installed at the bottom of each inclined support pile cap 6. During the excavation of the foundation pit, the soil between the steel inclined bracing 2 needs to be retained and not excavated. A soil slope 8 (slope 1:1.25) is set at the bottom of the steel inclined bracing 2. The soil slope 8 needs to be reinforced concrete facing (sprayed 100mm thick C20 concrete surface layer, with a single layer of bidirectional steel mesh with a diameter of 8mm and a spacing of 200mm), which increases the construction cost.

[0004] 2) During the construction of the base plate 5, due to the presence of the steel diagonal brace 2, it is necessary to weld the water-stop steel plate 9 to the support leg of the steel diagonal brace 2, which will affect the construction progress and pose a risk of leakage of the base plate 5. Summary of the Invention

[0005] To overcome the shortcomings of existing technologies, this invention provides a foundation pit retaining structure and its construction method, which accelerates the construction progress and reduces construction costs while ensuring the safety of foundation pit excavation, and also reduces the risk of leakage of the foundation pit bottom slab due to the retention of steel diagonal bracing.

[0006] To achieve the above objectives, the present invention provides a foundation pit retaining structure, comprising:

[0007] The pile arrangement consists of a row of bored piles evenly arranged at the edge of the foundation pit. An additional pile arrangement is provided on the side of the pile arrangement that is relatively far from the foundation pit. The additional pile arrangement is an evenly arranged row of piles with a pile spacing smaller than that of the pile arrangement. Both the pile arrangement and the additional pile arrangement are fixedly equipped with capping beams at their tops, and the two capping beams are fixedly connected by connecting beams.

[0008] Preferably, a reinforcing plate is fixedly installed on the top of the connecting beam, and the top elevation of the two capping beams is consistent with the top elevation of the reinforcing plate, and the bottom elevation of the two capping beams is consistent with the bottom elevation of the connecting beam.

[0009] Preferably, a water-stop curtain is fixedly installed on the side of the cast-in-place pile row near the additional pile row at a position between the cast-in-place pile row and the connecting beam.

[0010] Preferably, the water-stopping curtain is a row of high-pressure jet grouting piles that are evenly arranged and interlocked with each other.

[0011] A construction method for a foundation pit retaining structure, used for constructing the foundation pit retaining structure, the construction method comprising the following steps:

[0012] A row of bored piles is constructed evenly at the edge of the foundation pit to form a pile bank.

[0013] On the side of the cast-in-place pile row that is relatively far from the foundation pit, another row of piles is constructed in a uniform arrangement to form an additional pile row, and the spacing between the additional piles is smaller than the spacing between the cast-in-place pile rows.

[0014] A capping beam is installed on the top of the cast-in-place pile row and the additional pile row, and the two capping beams are fixedly connected by a connecting beam.

[0015] Preferably, a water-stop curtain is fixedly installed between the cast-in-place pile row and the connecting beam;

[0016] Before the two capping beams are fixedly connected by the connecting beam, a water-stop curtain is constructed on the side of the cast-in-place pile row near the additional pile row, so that the water-stop curtain is located between the connecting beam and the cast-in-place pile row after the two capping beams are fixedly connected by the connecting beam.

[0017] By adopting the above technical solution, the present invention has the following beneficial effects:

[0018] 1) By setting up pile rows with different pile spacing and additional pile rows, the two pile rows are connected by capping beams, connecting beams and reinforcing plates, which increases the integrity and eliminates the need for additional steel diagonal bracing, thus reducing construction costs.

[0019] 2) While ensuring the safety of the foundation pit excavation, the construction progress was accelerated, and the risk of leakage of the foundation pit bottom slab due to the retention of steel diagonal bracing was reduced. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a plan view of the original enclosure structure in the background art of this invention.

[0022] Figure 2 This is a cross-sectional view of the original enclosure structure in the background art of this invention.

[0023] Figure 3 This is a plan view of the foundation pit retaining structure in an embodiment of the present invention.

[0024] Figure 4 This is a cross-sectional view of the foundation pit retaining structure in an embodiment of the present invention.

[0025] The correspondence between the numbers in the attached diagram is as follows:

[0026] 1- Cast-in-place pile row; 2- Steel diagonal bracing; 3- Water-stop curtain; 4- Ring beam; 5- Base slab; 6- Diagonal bracing pile cap; 7- Cast-in-place pile; 8- Soil slope; 9- Water-stop steel plate; 10- Additional pile row; 11- Connecting beam; 12- Reinforcing plate; 13- Top beam; 14- Concrete force transfer strip. Detailed Implementation

[0027] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings. It should be noted that these descriptions are for the purpose of aiding understanding the present invention, but do not constitute a limitation thereof. Furthermore, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0028] Please see Figure 3 and Figure 4As shown, this embodiment of the invention provides a foundation pit retaining structure, including a row of cast-in-place piles 1. The row of cast-in-place piles 1 is a row of bored cast-in-place piles evenly arranged at the edge of the foundation pit. An additional row of piles 10, spaced a certain distance from the row of cast-in-place piles 1, is provided on the side of the row of cast-in-place piles 1 relatively away from the foundation pit. The additional row of piles 10 is a row of piles evenly arranged with a pile spacing smaller than that of the row of cast-in-place piles 1. A capping beam 13 is fixedly installed on the top of both the row of cast-in-place piles 1 and the additional row of piles 10, and the two capping beams 13 are fixedly connected by a connecting beam 11. It should be noted that in this embodiment, the specifications of the row of cast-in-place piles 1 are Φ900@1400 (diameter 900mm, spacing 1400mm), and the additional row of piles 10 also uses cast-in-place piles with specifications of Φ900@2800 (diameter 900mm, spacing 2400mm).

[0029] Furthermore, in this embodiment, a reinforcing plate 12 is fixedly installed on the top of the connecting beam 11, and the top elevation of the two capping beams 13 is consistent with the top elevation of the reinforcing plate 12, and the bottom elevation of the two capping beams 13 is consistent with the bottom elevation of the connecting beam 11.

[0030] Furthermore, in this embodiment, a water-stop curtain 3 is fixedly installed on the side of the cast-in-place pile row 1 near the additional pile row 10, at a position between the cast-in-place pile row 1 and the connecting beam 11. The water-stop curtain 3 is a row of high-pressure jet grouting piles (800mm in diameter, 600mm in spacing, and 10m in length) that are evenly arranged and interlocked with each other. It should be noted that in this embodiment, a concrete force transmission strip 14 (with the same strength grade and thickness as the bottom plate) is set between the bottom plate 5 and the cast-in-place pile row 1 for bottom plate replacement support. This technology is a publicly known prior art in the field of foundation pit support technology, and therefore will not be described in detail.

[0031] This invention also provides a construction method for a foundation pit retaining structure, used for constructing the aforementioned foundation pit retaining structure. The construction method includes the following steps:

[0032] A row of bored piles is constructed evenly at the edge of the foundation pit to form a pile bank.

[0033] On the side of the cast-in-place pile row that is relatively far from the foundation pit, another row of piles is constructed in a uniform arrangement to form an additional pile row, and the spacing between the additional piles is smaller than the spacing between the cast-in-place pile rows.

[0034] A capping beam is installed on the top of the cast-in-place pile row and the additional pile row, and the two capping beams are fixedly connected by a connecting beam. Finally, a reinforcing plate is constructed on the connecting beam so that the top elevation of the two capping beams is consistent with the top elevation of the reinforcing plate and the bottom elevation is consistent with the bottom elevation of the connecting beam.

[0035] It should be noted that in this embodiment, a water-stop curtain is fixedly installed between the cast-in-place pile row and the connecting beam. Before the two capping beams are fixedly connected by the connecting beam, the water-stop curtain is constructed on the side of the cast-in-place pile row near the additional pile row, so that the water-stop curtain is located between the connecting beam and the cast-in-place pile row after the two capping beams are fixedly connected by the connecting beam.

[0036] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention is not limited to the described embodiments. For those skilled in the art, various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and these variations still fall within the protection scope of the present invention.

Claims

1. A foundation pit retaining structure, characterized in that, The structure includes a row of bored piles, which consists of a row of bored piles evenly arranged at the edge of the foundation pit. An additional row of piles is provided on the side of the piles relatively away from the foundation pit, which is spaced at a certain distance from the piles. The additional row of piles is a row of piles evenly arranged with a pile spacing smaller than that of the piles in the piles. Both the piles and the additional row of piles are fixedly fitted with capping beams, and the two capping beams are fixedly connected by connecting beams.

2. The foundation pit retaining structure as described in claim 1, characterized in that: A reinforcing plate is fixedly installed on the top of the connecting beam, and the top elevation of the two capping beams is consistent with the top elevation of the reinforcing plate, and the bottom elevation of the two capping beams is consistent with the bottom elevation of the connecting beam.

3. The foundation pit retaining structure as described in claim 2, characterized in that: A water-stop curtain is fixedly installed on the side of the cast-in-place pile row near the additional pile row, at a position between the cast-in-place pile row and the connecting beam.

4. The foundation pit retaining structure as described in claim 3, characterized in that: The water-stopping curtain is a row of high-pressure jet grouting piles that are evenly arranged and interlocked with each other.

5. A construction method for a foundation pit retaining structure, characterized in that, The construction method for constructing the foundation pit retaining structure as described in claim 1 includes the following steps: A row of bored piles is constructed evenly at the edge of the foundation pit to form a pile bank. On the side of the cast-in-place pile row that is relatively far from the foundation pit, another row of piles is constructed in a uniform arrangement to form an additional pile row, and the spacing between the additional piles is smaller than the spacing between the cast-in-place pile rows. A capping beam is installed on the top of the cast-in-place pile row and the additional pile row, and the two capping beams are fixedly connected by a connecting beam.

6. The construction method of the foundation pit retaining structure as described in claim 5, characterized in that: A water-stop curtain is fixedly installed between the cast-in-place pile row and the connecting beam; Before the two capping beams are fixedly connected by the connecting beam, a water-stop curtain is constructed on the side of the cast-in-place pile row near the additional pile row, so that the water-stop curtain is located between the connecting beam and the cast-in-place pile row after the two capping beams are fixedly connected by the connecting beam.

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