Half-cover deep excavation foundation pit supporting system in soft soil area

Abstract

The utility model discloses a soft soil area half cover excavation deep foundation pit supporting system which comprises an advanced construction structure, an enclosure structure, an inner supporting structure and a trestle structure, the inner supporting structure comprises a large-diameter double-circular-ring inner support, a middle horizontal diagonal brace and an angle brace, and the horizontal projection position of the advanced construction structure in a construction field is a cover excavation area. The rest part is an open excavation area, at least 80% of the first construction structure of the cover excavation area is located within the range defined by the large-diameter double-circular-ring inner support, the first construction structure of the rest part of the cover excavation area is fixedly connected with the inner support structure, and the trestle structure is fixedly connected with the enclosure structure and the inner support structure. An earth excavation soil slope is arranged on the extension line of the end of the trestle structure and extends to the cover excavation area from the trestle structure. The projection overlapping area of an advanced construction structure and the inner support can be effectively reduced, the excavation efficiency of the half-cover deep excavation foundation pit is improved, the earth excavation difficulty is reduced, meanwhile, reinforced concrete materials are saved through the double circular ring supports, and cost is reduced.

Description

Technical Field

[0001] The utility model belongs to the field of deep foundation pit support, in particular to a semi-covered deep foundation pit support system in soft soil areas. Background Art

[0002] With the vigorous development of urban underground construction, deep foundation pit projects have become more and more numerous. During construction, the area of ​​foundation pits has been continuously expanded, and the excavation depth of foundation pits has been continuously deepened.

[0003] Currently, the primary support method used for deep foundation pit excavation in soft soil areas is open-cut. This involves installing underground diaphragm walls and support piles around the perimeter of the pit, followed by reinforced concrete supports and trestle bridges within the pit. Open-cut construction involves first excavating the ground, then conducting construction work in the open air, and finally covering and backfilling the pit. This approach offers low construction costs and high safety, but can significantly impact surrounding structures.

[0004] When there are obstructions within the foundation pit, such as when a pre-existing building structure appears within the pit due to different construction schedules, existing construction methods require a covered excavation to minimize the impact of pit construction on the pre-existing building structure. This involves excavating from the ground to a certain depth, sealing the top, and allowing the remainder of the pit construction to proceed beneath the sealed roof. However, covered excavation requires a large amount of excavated and transported earth from the bottom, resulting in low excavation efficiency for long-arm excavators, which can easily impact construction schedules.

[0005] At present, the construction period of the main structure is relatively fixed and routine. Therefore, how to ensure the construction quality and safety of deep foundation pit projects while appropriately selecting support methods and shortening the construction period when there are obstructions inside the foundation pit is the current main research area and direction of the industry. Utility Model Content

[0006] The purpose of the utility model is to provide a semi-covered deep foundation pit support system in soft soil areas, which aims to solve the technical problems that open excavation cannot be used when there are obstructions inside the deep foundation pit in existing soft soil areas, the amount of bottom earth excavated and transported when using covered excavation construction is large, the excavation efficiency of the long-arm excavator is low, and the construction period is easily affected.

[0007] In order to achieve the above purpose, the present invention adopts the following technical solutions:

[0008] A semi-covered deep foundation pit support system in soft soil areas, including a preliminary construction structure, a retaining structure, an internal support structure and a trestle structure.

[0009] The retaining structure is set up along the edge of the foundation pit, and the scope of the foundation pit is the scope of the construction site.

[0010] The internal support structure includes large-diameter double-circular inner supports, intermediate horizontal braces and angle supports. The horizontal projection position of the advance construction structure in the construction site is the cover excavation area, and the rest is the open excavation area. At least 80% of the advance construction structure in the cover excavation area is located within the range enclosed by the large-diameter double-circular inner supports. The advance construction structure in the rest of the cover excavation area is fixedly connected to the internal support structure.

[0011] The large diameter double ring inner support includes support columns, first ring horizontal support and second ring horizontal support.

[0012] The middle horizontal brace is located at the junction of the first circular horizontal support and the second circular horizontal support. The two ends of the middle horizontal brace are longitudinally connected to the enclosure structure on the opposite side. The middle horizontal brace includes two rows of brace columns, brace main beams and brace tension beams. The brace main beams are arranged along the same row of brace columns, and the brace tension beams are connected between the two rows of brace columns.

[0013] The corner braces are set between the large diameter double ring inner support and the surrounding structure.

[0014] Both ends of the trestle structure 3 are fixedly connected to the enclosure structure 2, and both sides of the trestle structure are fixedly connected to the inner support structure. An earth excavation ramp is provided on the end extension line of the trestle structure, and the earth excavation ramp extends from the trestle structure to the cover excavation area.

[0015] The advance construction structure and the internal support structure are fixedly connected by semi-covered excavated tension beams.

[0016] The pre-construction structure includes a vertical support structure, which is fixedly connected to the supporting columns, the first circular horizontal support, the second circular horizontal support, the opposing supporting columns or the opposing supporting main beams through a semi-covered excavated beam;

[0017] The prior construction structure also includes structural horizontal tension beams between the structural vertical supports. The structural horizontal tension beams are fixedly connected to the supporting columns, the first circular horizontal supports, the second circular horizontal supports, the opposing supporting columns or the opposing supporting main beams through semi-covered excavated tension beams.

[0018] There are two large-diameter double-ring internal supports set along the depth direction of the foundation pit, namely the first internal support and the second internal support. The first internal support is located directly above the second internal support. The trestle structure is located above the first internal support, including trestle columns and trestle tension beams. The trestle tension beams are connected between the trestle columns.

[0019] The trestle structure includes the first trestle, the second trestle and the third trestle.

[0020] The horizontal projection of the first trestle is located within the first circular horizontal support. The outer end of the first trestle is fixedly connected to the outer enclosure structure of the first circular horizontal support. The other end of the first trestle extends toward the central support of the first circular horizontal support and is located in the open-cut area within the first circular horizontal support.

[0021] The horizontal projection of the second trestle is located directly above the middle horizontal support. The second trestle extends toward the center along the middle horizontal support until it is inside the second circular horizontal support. One end of the second trestle is fixedly connected to the enclosure structure, and the other end of the second trestle is set in the open-cut area inside the second circular horizontal support.

[0022] The horizontal projection of the third trestle is located within the angle support range outside the second circular horizontal support. One end of the third trestle is fixedly connected to the enclosure structure, and the other end is arranged along the second circular horizontal support and fixedly connected to the second circular horizontal support.

[0023] The slope of the earth excavation ramp is 1 / 6-1 / 12.

[0024] A first earthen ramp is provided in the first circular horizontal support, the first earthen ramp connects the first trestle and the covered excavation area in the first circular horizontal support, a second earthen ramp is provided in the second circular horizontal support, the second earthen ramp connects the second trestle and the covered excavation area in the second circular horizontal support,

[0025] The backhoe is located at the bottom of the cover excavation area or at the end of the earth ramp for earth excavation.

[0026] Compared with the prior art, the present invention has the following characteristics and beneficial effects:

[0027] The utility model discloses a semi-covered deep foundation pit support system in a soft soil area, wherein an inner support is provided to reduce the overlap with the projection of the preceding construction structure, the inner support is in the form of a large-diameter double-circular ring inner support and an intermediate opposite support, and then the preceding construction structure and the large-diameter double-circular ring inner support and the intermediate opposite support are fixedly connected by a steel tension beam, and at the same time a trestle is provided on the upper part of the first inner support, an earth ramp is located on the extension line of the end of the trestle, is affected by the preceding construction structure, and extends to the influence area of ​​the steel tension beam, and a backhoe is located at the bottom of the steel tension beam or the end of the earth ramp.

[0028] The utility model can effectively carry out the construction deployment and organization of deep foundation pit excavation, can effectively reduce the projection overlap area of ​​the preceding construction structure and the internal support, improve the excavation efficiency of the semi-covered deep foundation pit, reduce the difficulty of earth excavation, and at the same time, the double circular ring support saves reinforced concrete materials and reduces costs.

[0029] The utility model rationally designs the positions of the trestle and the earth ramp, optimizes the travel route of the earth transport vehicle, and utilizes multi-region, small-area, group-coordinated symmetrical excavation technology to effectively improve the excavation efficiency and shorten the overall construction period.

[0030] During the construction of the utility model, the earth around the first construction structure is excavated first. After the excavation is completed, the excavation is carried out from the outside to the inside around the first construction structure. The foundation pit is excavated symmetrically on the north and south sides as a whole. The earth in the cover excavation area is relayed and transported to the earth ramp, and the construction route is clear. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The present invention will be further described in detail below with reference to the accompanying drawings.

[0032] Figure 1 It is a plan view of a semi-covered deep foundation pit support system for soft soil areas according to the utility model.

[0033] Figure 2 It is a schematic plan view of the first step of earth excavation of the present invention.

[0034] Figure 3 It is a schematic plan view of the second and third steps of earth excavation of the present utility model.

[0035] Figure 4 It is a schematic plan view of the earth excavation finishing of the utility model.

[0036] Figure 5 It is a schematic cross-sectional view of the third step of earth excavation of the present utility model.

[0037] Figure 6 It is a schematic cross-sectional view of the earth excavation finishing of the utility model.

[0038] Figure numbers: 1-preliminary construction structure, 11-structural vertical support, 12-structural horizontal tension beam, 1a-first structure, 2a-second structure, 3a-third structure, 2-enclosing structure, 21-underground continuous wall, 22-support piles, 3-trestle structure, 31-trestle column, 32-trestle tension beam, 3a-first trestle, 3b-second trestle, 3c-third trestle, 4-large diameter double ring inner support, 41-support column, 42-first ring Horizontal support, 43-second circular horizontal support, 4a-first inner support, 4b-second inner support, 5-middle horizontal bracing, 51-bracing column, 52-bracing main beam, 53-bracing tension beam, 6-angle bracing, 7-cover excavation area, 8-earth excavation ramp, 81-first earth ramp, 82-second earth ramp, 9-semi-cover excavation tension beam, 10-backhoe, 13-initial earth ramp, 14-earthwork, 15-earthwork long-arm excavator. DETAILED DESCRIPTION

[0039] For example, see Figure 1-6 As shown, a semi-covered deep foundation pit support system in soft soil areas includes an advance construction structure 1, a retaining structure 2, an internal support structure and a trestle structure 3.

[0040] The retaining structure 2 is arranged around the edge of the foundation pit, and the scope of the foundation pit is the scope of the construction site. In this embodiment, the retaining structure 2 includes an underground continuous wall 21 and support piles 22.

[0041] The internal support structure includes a large-diameter double-circular ring internal support 4, an intermediate horizontal brace 5 and a corner brace 6. The horizontal projection position of the advance construction structure 1 in the construction site is the covered excavation area 7, and the rest is the open excavation area. At least 80% of the advance construction structure 1 in the covered excavation area 7 is located within the range enclosed by the large-diameter double-circular ring internal support 4, and the advance construction structure 1 in the rest of the covered excavation area 7 is fixedly connected to the internal support structure.

[0042] The large-diameter double-circular ring inner support 4 includes a support column 41, a first circular ring horizontal support 42 and a second circular ring horizontal support 43. The large-diameter double-circular ring inner support 4 is provided with two rows along the depth direction of the foundation pit, namely the first inner support 4a and the second inner support 4b. The first inner support 4a is located directly above the second inner support 4b.

[0043] The middle horizontal brace 5 is located at the junction of the first circular horizontal support 42 and the second circular horizontal support 43. The two ends of the middle horizontal brace 5 are longitudinally connected to the enclosure structure 2 on the opposite side. The middle horizontal brace 5 includes two rows of brace columns 51, brace main beams 52 and brace tension beams 53. The brace main beams 52 are arranged along the same row of brace columns 51. The brace tension beams 53 are connected between the two rows of brace columns 51.

[0044] The angle brace 6 is arranged around the large-diameter double-circular ring inner support 4 and between the enclosure structure 2 .

[0045] The pre-construction structure 1 is fixedly connected to the inner support structure through a semi-covered excavation beam 9 .

[0046] In this embodiment, the advance construction structure 1 includes three parts, namely the first structure 1a, the second structure 2a and the third structure 3a, wherein the first structure 1a is located in the first circular horizontal support 42, the second structure 2a is located in the second circular horizontal support 43, and the third structure 3a spans the first circular horizontal support 42 and the second circular horizontal support 43 through the intermediate horizontal support 5.

[0047] The advance construction structure 1 includes a structural vertical support 11 , which is fixedly connected to the supporting columns 41 , the first circular horizontal support 42 , the second circular horizontal support 43 , the opposing supporting columns 51 or the opposing supporting main beams 52 via a semi-covered excavated beam 9 .

[0048] The advance construction structure 1 also includes a structural horizontal tension beam 12 between the structural vertical supports 11, and the structural horizontal tension beam 12 is fixedly connected to the supporting columns 41, the first circular horizontal support 42, the second circular horizontal support 43, the supporting columns 51 or the supporting main beams 52 through the semi-covered excavated tension beam 9.

[0049] In this embodiment, the third structure 3a is fixedly connected between the vertical support 11 and the supporting column 41 through the semi-covered hollowed beam 9. At the same time, the vertical support 11 and the supporting column 51 are also fixedly connected through the semi-covered hollowed beam 9.

[0050] The trestle structure 3 is located above the first inner support 4 a and includes trestle columns 31 and trestle tension beams 32 . The trestle tension beams 32 are tensioned between the trestle columns 31 .

[0051] The ends of the trestle structure 3 are fixedly connected to the enclosure structure 2, and the sides of the trestle structure 3 are fixedly connected to the internal support structure. The trestle structure 3 includes a first trestle 3a, a second trestle 3b, and a third trestle 3c. The first trestle 3a and the second trestle 3b are used for excavation, and the third trestle 3c is used for material storage and the layout of the steel bar processing area.

[0052] The horizontal projection of the first trestle 3a is located within the first circular horizontal support 42. The outer end of the first trestle 3a is fixedly connected to the retaining structure 2 outside the first circular horizontal support 42. The other end of the first trestle 3a extends toward the central support of the first circular horizontal support 42 and is set in the open excavation area within the first circular horizontal support 42.

[0053] The horizontal projection of the second trestle 3b is located directly above the middle horizontal support 5. The second trestle 3b extends toward the center along the position of the middle horizontal support 5 until it reaches the second circular horizontal support 43. One end of the second trestle 3b is fixedly connected to the retaining structure 2, and the other end of the second trestle 3b is arranged in the open excavation area within the second circular horizontal support 43.

[0054] The horizontal projection of the third trestle 3c is located within the range of the angle support 6 outside the second circular horizontal support 43. One end of the third trestle 3c is fixedly connected to the enclosure structure 2, and the other end is arranged along the second circular horizontal support 43 and fixedly connected to the second circular horizontal support 43.

[0055] An earthwork ramp 8 is provided along the extension of the end of the trestle structure 3. This ramp extends from the trestle structure 3 to the covered excavation area 7, where excavated earth is relayed to the ramp 8. The slope of this ramp 8 is 1 / 6 to 1 / 12, and the backhoe 10 is positioned at the bottom of the covered excavation area 7 or at the end of this ramp 8. A first earthwork ramp 81 is provided within the first circular horizontal support 42, connecting the first trestle 3a with the covered excavation area 7 within the first circular horizontal support 42. A second earthwork ramp 82 is provided within the second circular horizontal support 43, connecting the second trestle 3b with the covered excavation area 7 within the second circular horizontal support 43.

[0056] The construction process of this utility model is as follows:

[0057] Step 1: Design the internal support structure and trestle structure 3 according to the location of the foundation pit and the location of the pre-construction structure 1. When designing, ensure that the overlap between the cover and excavation area of ​​the pre-construction structure 1 and the projection of the ring is minimized. Figure 1 shown.

[0058] Step 2: First, excavate the earthwork to the bottom of the first inner support 4a, and use a temporary initial earth ramp 13 for excavation, which is set between the trestle structure 3 and the cover excavation area. Figure 2 shown.

[0059] Step three: construct the first inner support 4a, the first trestle 3a and the second trestle 3b to ensure subsequent earth excavation.

[0060] Step 4: After the concrete strength grade of the first inner support 4a, the first trestle 3a and the second trestle 3b reaches 80%, the construction of the semi-covered excavated beam 9 between the inner support structure, the trestle structure and the pre-construction structure 1 begins.

[0061] Step five, start the second step of earth excavation to the bottom of the second inner support 4b. Use double center island earth excavation for large open excavation. Excavation is carried out symmetrically as a whole, and construction is carried out in sections and blocks. The earth near the construction structure 1 and the bottom is excavated in multiple areas, small areas, and in a coordinated manner by small excavators. A ramp is left at the center island position, namely the earth excavation ramp 8.

[0062] Step 6: The concrete strength grade of the second inner support 4b reaches 80%, and the inner support structure, the trestle structure and the pre-construction structure 1 are fixedly connected by the semi-covered excavation beam 9.

[0063] Step 7: Start the third step of excavation to the bottom of the pit. Affected by the semi-covered excavation beam 9, the soil around the first construction structure 1 is excavated. After the excavation is completed, the excavation is carried out from the outside to the inside around the first construction structure 1. The foundation pit is excavated symmetrically on the north and south sides. Figure 3 and Figure 5 shown.

[0064] Step 8: When the excavation is completed in sections and blocks to the bottom of the foundation pit, the first trestle 3a is used as the final excavation point, and the earthwork at the second trestle 3b is transported to the first trestle 3a by an excavator, that is, the earthwork 14 is completed to the end position of the first trestle 3a, and finally the long-arm excavator 15 is used to excavate the earthwork. Figure 4 and Figure 6 shown.

Claims

1. A semi-covered deep foundation pit support system in soft soil areas, characterized by: It includes the pre-construction structure (1), the enclosure structure (2), the internal support structure and the trestle structure (3). The retaining structure (2) is set up along the edge of the foundation pit, and the scope of the foundation pit is the scope of the construction site. The internal support structure includes a large-diameter double-circular ring internal support (4), an intermediate horizontal brace (5) and an angle brace (6). The horizontal projection position of the advance construction structure (1) in the construction site is the cover excavation area (7), and the rest is the open excavation area. At least 80% of the advance construction structure (1) in the cover excavation area (7) is located within the range enclosed by the large-diameter double-circular ring internal support (4). The advance construction structure (1) in the rest of the cover excavation area (7) is fixedly connected to the internal support structure. The large-diameter double-circular ring inner support (4) includes a support column (41), a first circular ring horizontal support (42) and a second circular ring horizontal support (43). The middle horizontal brace (5) is located at the junction of the first circular horizontal support (42) and the second circular horizontal support (43). Both ends of the middle horizontal brace (5) are longitudinally connected to the enclosure structure (2) on the opposite side. The middle horizontal brace (5) includes two rows of brace columns (51), a brace main beam (52) and a brace tension beam (53). The brace main beam (52) is arranged along the same row of brace columns (51). The brace tension beam (53) is stretched between the two rows of brace columns (51). The angle brace (6) is arranged around the large diameter double ring inner support (4) and between the enclosure structure (2). The two ends of the trestle structure (3) are fixedly connected to the enclosure structure (2), and the two sides of the trestle structure (3) are fixedly connected to the inner support structure. An earth excavation ramp (8) is provided on the extension line of the end of the trestle structure (3), and the earth excavation ramp (8) extends from the trestle structure (3) to the cover excavation area (7).

2. The semi-covered deep foundation pit support system for soft soil areas according to claim 1 is characterized by: The pre-construction structure (1) is fixedly connected to the inner support structure via a semi-covered excavation beam (9).

3. The semi-covered deep foundation pit support system for soft soil areas according to claim 2 is characterized in that: The pre-construction structure (1) includes a structural vertical support (11), and the structural vertical support (11) is fixedly connected to the supporting column (41), the first circular horizontal support (42), the second circular horizontal support (43), the supporting column (51) or the supporting main beam (52) through a semi-covered excavation beam (9); The pre-construction structure (1) further includes a structural horizontal tension beam (12) between the structural vertical supports (11), and the structural horizontal tension beam (12) is fixedly connected to the supporting column (41), the first circular horizontal support (42), the second circular horizontal support (43), the opposing supporting column (51) or the opposing supporting main beam (52) through the semi-covered excavated tension beam (9).

4. The semi-covered deep foundation pit support system for soft soil areas according to any one of claims 1 to 3, characterized in that: Two large-diameter double-circular inner supports (4) are provided along the depth direction of the foundation pit, namely a first inner support (4a) and a second inner support (4b). The first inner support (4a) is located directly above the second inner support (4b). The trestle structure (3) is located above the first inner support (4a) and includes trestle columns (31) and trestle tension beams (32). The trestle tension beams (32) are tensioned between the trestle columns (31).

5. The semi-covered deep foundation pit support system for soft soil areas according to claim 4 is characterized in that: The trestle structure (3) includes a first trestle (3a), a second trestle (3b) and a third trestle (3c), The horizontal projection of the first trestle (3a) is located within the first circular horizontal support (42), the outer end of the first trestle (3a) is fixedly connected to the outer enclosure structure (2) of the first circular horizontal support (42), and the other end of the first trestle (3a) extends toward the central support of the first circular horizontal support (42) and is arranged in an open-cut area within the first circular horizontal support (42). The horizontal projection of the second trestle (3b) is located directly above the middle horizontal support (5). The second trestle (3b) extends toward the center along the position of the middle horizontal support (5) until it is inside the second circular horizontal support (43). One end of the second trestle (3b) is fixedly connected to the enclosure structure (2), and the other end of the second trestle (3b) is arranged in an open-cut area inside the second circular horizontal support (43). The horizontal projection of the third trestle (3c) is located within the range of the angle support (6) outside the second circular horizontal support (43). One end of the third trestle (3c) is fixedly connected to the enclosure structure (2), and the other end is arranged along the second circular horizontal support (43) and fixedly connected to the second circular horizontal support (43).

6. The semi-covered deep foundation pit support system for soft soil areas according to claim 5 is characterized by: The slope of the earth excavation ramp (8) is 1 / 6-1 / 12.

7. The semi-covered deep foundation pit support system for soft soil areas according to claim 6 is characterized in that: A first earthen ramp (81) is provided in the first circular horizontal support (42), and the first earthen ramp (81) connects the first trestle (3a) and the cover excavation area (7) in the first circular horizontal support (42). A second earthen ramp (82) is provided in the second circular horizontal support (43), and the second earthen ramp (82) connects the second trestle (3b) and the cover excavation area (7) in the second circular horizontal support (43).

8. The semi-covered deep foundation pit support system for soft soil areas according to any one of claims 1, 5-7, characterized in that: The backhoe (10) is located at the bottom of the cover excavation area (7) or at the end of the earth excavation ramp (8).

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