A pile-anchor support structure for foundation pits without girders and its construction technology

Abstract

This invention belongs to the field of underground engineering technology, specifically relating to a non-pillar-anchored support structure and construction process for foundation pits. It includes a retaining plate with ducts A on both sides. Threaded reinforcing bars are pre-embedded in the support piles, passing through ducts A. Inside the retaining plate is a duct B, in which a steel pipe is pre-embedded. An anchor head plate is pre-embedded at the front end of duct B, and an anchor cable passes through the steel pipe. The anchor point of the anchor cable is welded to the anchor head plate. Duct B is filled with grout. This invention significantly improves the lateral pressure resistance of the foundation pit support structure, ensures the stability of the soil between piles, eliminates the traditional pillar-anchored structure, expands the usable space for foundation pit construction, facilitates the main structure and waterproofing construction, and improves construction efficiency.

Description

Technical Field

[0001] This invention belongs to the field of underground engineering technology, specifically relating to a foundation pit non-waist beam pile anchor support structure and construction technology. Background Technology

[0002] With the continuous development of urbanization, the development and utilization of underground space is becoming more and more widespread, and the depth of urban excavation is getting deeper and deeper. As the depth of foundation pits continues to increase, the requirements for the safety and stability of foundation pit support are also getting higher and higher. The existing foundation pit support usually uses a combination structure of pile foundation, waist beam and cross brace to ensure the stability and safety of the entire foundation pit. However, this construction process has the following shortcomings: (1) The waist beam is large in size, and the installation and dismantling construction is relatively difficult; (2) The waist beam is arranged outside the pile foundation, which occupies the foundation pit space. It needs to be partially dismantled during the construction of the main structure, which affects the construction period; (3) The soil reinforcement between the support piles is not effectively connected to the support piles, and the overall support stiffness is insufficient, which affects the safety of the foundation pit. Summary of the Invention

[0003] To address the shortcomings of existing technologies, this invention provides a foundation pit non-waist beam pile anchor support structure and construction process.

[0004] This invention is achieved through the following technical solution:

[0005] A non-waisted pile anchor support structure for foundation pits includes a horizontal embedding plate located between two support piles. The embedding plate has a trapezoidal cross-section. The left and right inclined end faces of the embedding plate contact the sides of the support piles. The rear end face of the embedding plate, where the short side is located, is located on the side closest to the support pile. The front end face of the embedding plate, where the long side is located, is on the same vertical plane as the frontmost end face of the support pile. Channels A are provided inside both sides of the embedding plate from the front end face to the inclined end face. Threaded steel bars are pre-embedded in the support piles, passing through channels A. The front ends of the threaded steel bars are fixed to the embedding plate by nuts. Channel B is provided in the middle of the embedding plate. A steel pipe is pre-embedded in channel B. The angle of the steel pipe is the same as the inclination angle of the anchor cable. An anchor head pad is pre-embedded at the front end of channel B. The anchor head pad is flush with the front end face of the embedding plate. The anchor cable passes through the steel pipe, and the anchor point of the anchor cable is welded to the anchor head pad. Grouting material is injected into channel B.

[0006] Preferably, the length of the threaded steel bar extending into the support pile is 15cm, and the length extending out of the support pile is 17cm.

[0007] Preferably, the channel A is configured as two parallel channels running vertically.

[0008] Preferably, the steel pipe is a galvanized steel pipe.

[0009] Preferably, the thickness of the mounting plate is 30cm.

[0010] This invention also includes a construction process for pile anchor support without waist beam in foundation pits, comprising the following steps:

[0011] Step 1: When binding the reinforcing cage of the support pile, pre-embed the connecting threaded steel bars, then install the reinforcing cage and pour concrete to complete the construction of the support pile.

[0012] Step 2: After the support piles reach the design strength, the foundation pit is excavated. The foundation pit is excavated in layers from top to bottom. After each layer is excavated, a steel mesh is laid on the surface of the soil between the piles, and a layer of shotcrete is sprayed.

[0013] Step 3: Pass the threaded steel bars of the two adjacent support piles through the holes A on both sides of the embedded plate, and fix the threaded steel bars with nuts after passing through the embedded plate;

[0014] Step 4: Drill holes for anchor bolts through hole B on the mounting plate, install anchor cables, pass through the steel pipe, and weld the front anchor point of the anchor cable to the anchor head plate. At the same time, inject grout into hole B.

[0015] This invention provides a non-waist beam pile-anchor support structure and construction process for foundation pits. By pre-embedding threaded steel bars on the support piles and connecting them to reserved channels A on the embedding plate, and connecting the embedding plate to the anchor cable, the entire foundation pit support structure is combined into an integrated support system, thereby greatly improving the lateral pressure resistance of the foundation pit support structure and ensuring the stability of the soil between piles. At the same time, the waist beam structure in the traditional process is eliminated, expanding the construction space of the foundation pit, facilitating the construction of the main structure and waterproofing, and improving construction efficiency. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of the present invention.

[0017] Figure 2 This is a top view of the structure of the present invention.

[0018] In the diagram: 1. Support pile, 2. Embedding plate, 3. Threaded steel bar, 4. Nut, 5. Steel pipe, 6. Anchor cable, 7. Anchor head pad, 8. Reinforcing cage, 9. Concrete layer. Detailed Implementation

[0019] The following are specific embodiments of the present invention with reference to the accompanying drawings. It should be noted that the present invention is not limited to the following specific embodiments, and all equivalent modifications made based on the technical solutions of this application are within the protection scope of the present invention.

[0020] This invention includes a retaining plate 2, preferably with a thickness of 30 cm. The retaining plate 2 is horizontally placed between two adjacent support piles 1 and connected to them. The cross-section of the retaining plate 2 is trapezoidal. The left and right inclined end faces of the retaining plate 2 contact the outer surfaces of the two adjacent support piles 1 respectively. The rear end face of the retaining plate 2, where the short side is located, is located closer to the support pile 1, and the front end face of the retaining plate 2, where the long side is located, is located away from the support pile 1. The front end face of the retaining plate 2, where the long side is located, is on the same vertical plane as the frontmost edge of the outer surfaces of the two adjacent support piles 1, meaning that the retaining plate 2 does not protrude from the support piles 1 and occupy additional space in the foundation pit.

[0021] Holes A are provided inside the left and right sides of the mounting plate 2, extending from the front end face to the inclined end face of the mounting plate 2. Two parallel holes A are provided on each side. Corresponding to holes A, threaded steel bars 3 are pre-embedded in the support pile 1, passing through holes A. Two parallel threaded steel bars 3 are also pre-embedded on each side. One end of the threaded steel bar 3 is located inside the support pile 1, and the other end passes through hole A and is fixed to the mounting plate 2 by a nut 4. Preferably, the length of the threaded steel bar 3 extending into the support pile 1 is 15cm, the length extending out of the support pile 1 is 17cm, and the length of the front end protruding from the mounting plate 2 is 2cm.

[0022] A channel B is provided inside the middle of the embedded plate 2, penetrating both the front and rear faces of the embedded plate 2. A galvanized steel pipe 5 is pre-embedded within the channel B, with its angle matching the inclination angle of the subsequently installed anchor cable 6. An anchor head plate 7 is pre-embedded at the front end of the channel B, with its front face flush with the front face of the embedded plate 2. An anchor cable 6 passes through the steel pipe 5 and is driven into the soil, with its anchor point welded to the anchor head plate 7. Grouting material is injected into the channel B to seal it.

[0023] A construction process for foundation pit pile anchor support without wainscoting, utilizing the foundation pit pile anchor support structure of the present invention, includes the following steps:

[0024] Step 1: Construction of Support Piles 1

[0025] First, the construction of support pile 1 is carried out. When the steel cage 8 of support pile 1 is tied, the connecting threaded steel bars 3 are pre-embedded according to the design interval size. Then, the steel cage 8 is installed and concrete is poured to complete the construction of support pile 1.

[0026] Step 2: Excavation of the foundation pit

[0027] After the support pile 1 reaches the design strength, the foundation pit is excavated. The foundation pit is excavated in layers from top to bottom. After each layer is excavated, steel mesh is laid on the surface of the soil between the piles, and sprayed concrete layer 9 is applied.

[0028] Step 3: Installing the mounting plate 2

[0029] Align the holes A on both sides of the mounting plate 2 with the threaded steel bars 3 of the two adjacent support piles 1 respectively, and let the threaded steel bars 3 pass through the holes A on both sides of the mounting plate 2 respectively. After the threaded steel bars 3 pass through the mounting plate 2, they are fixed by nuts 4, so that the two sides of the mounting plate 2 are firmly connected to the support piles 1 respectively.

[0030] Step 4: Install anchor cables 6

[0031] Anchor bolts are drilled through pre-embedded holes B on the anchor plate 2 and steel pipe 5. Anchor cables 6 are then installed and driven into the soil. The anchor points of anchor cables 6 are welded to pre-embedded anchor head plates 7. Simultaneously, grout is injected into hole B to seal it. This connects the support piles 1, anchor plate 2, and anchor cables 6, forming a unified support structure that significantly enhances the overall support strength of the foundation pit.

[0032] The embodiments described above are merely one preferred embodiment of the present invention. Ordinary variations and substitutions made by those skilled in the art within the scope of the present invention should be included within the protection scope of the present invention.

Claims

1. A construction process for a foundation pit non-waist beam pile anchor support structure, characterized in that, The structure includes a pile anchor support structure for foundation pits without waist beams, comprising a horizontal embedded plate (2) located between two support piles (1). The embedded plate (2) has a trapezoidal cross-section. The left and right inclined end faces of the embedded plate (2) are in contact with the side of the support pile (1). The rear end face of the short side of the embedded plate (2) is located on the side closer to the support pile (1). The front end face of the long side of the embedded plate (2) is on the same vertical plane as the front end of the side of the support pile (1). The embedded plate (2) has a channel A on both the left and right sides from the front end face to the inclined end face. Threaded steel bars (3) are pre-embedded on the support pile (1) through the channel A. 3) The front end is fixed to the embedded plate (2) by a nut (4). The length of the threaded steel bar (3) extending into the support pile (1) is 15cm and the length extending out of the support pile (1) is 17cm. A channel B is provided in the middle of the embedded plate (2). A steel pipe (5) is embedded in the channel B. The angle of the steel pipe (5) is the same as the inclination angle of the anchor cable (6). An anchor head pad (7) is embedded at the front end of the channel B. The anchor head pad (7) is flush with the front end of the embedded plate (2). The anchor cable (6) passes through the steel pipe (5). The anchor point of the anchor cable (6) is welded to the anchor head pad (7). Grouting material is injected into the channel B. The construction process includes the following steps: Step 1: When binding the reinforcing cage (8) of the support pile (1), pre-embed the connecting threaded steel bars (3), then install the reinforcing cage (8) and pour concrete to complete the construction of the support pile (1); Step 2: After the support piles (1) reach the design strength, the foundation pit is excavated. The foundation pit is excavated in layers from top to bottom. After each layer is excavated, steel mesh is laid on the soil surface between the piles and a layer of shotcrete (9) is sprayed. Step 3: Pass the threaded steel bars (3) of the two adjacent support piles (1) through the holes A on both sides of the embedded plate (2) respectively. After the threaded steel bars (3) pass through the embedded plate (2), they are fixed by nuts (4). Step 4: Drill the anchor bolt through the hole B on the embedded plate (2), install the anchor cable (6), the anchor cable (6) passes through the steel pipe (5), the front anchor point of the anchor cable (6) is welded to the anchor head pad (7), and grout is injected into the hole B at the same time.

2. The construction process of the foundation pit non-waist beam pile anchor support structure according to claim 1, characterized in that: The channel A is configured as two parallel channels running vertically.

3. The construction process of the foundation pit non-waist beam pile anchor support structure according to claim 1, characterized in that: The steel pipe (5) is a galvanized steel pipe.

4. The construction process of the foundation pit non-waist beam pile anchor support structure according to claim 1, characterized in that: The thickness of the mounting plate (2) is 30cm.

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