Supporting structure of ultra-deep foundation pit under moderate weathering condition
By employing a combined support structure of steel pipe piles, anchor rods, concrete surface layer, waist beams, and cap beams in moderately weathered soil environments, combined with drainage pipes, the problem of instability in foundation pits in moderately weathered soils using traditional support techniques was solved, achieving a support effect that is highly safe to construct, low in cost, and highly adaptable.
Patent Information
- Application Number
- CN202520519881.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-24
- Publication Date
- 2026-02-24
- Estimated Expiration
- 2035-03-24
AI Technical Summary
Traditional single pile foundation support technology cannot effectively guarantee the safety and stability of the foundation pit in moderately weathered soil environment, resulting in large engineering volume, high cost, and insufficient anti-sliding and anti-overturning capabilities.
The system employs a combined support structure consisting of steel pipe piles, anchor rods, concrete surface layer, wainscoting, and capping beams. Drainage is achieved through drainage pipes, with steel pipe piles providing lateral support, anchor rods enhancing stability, wainscoting and capping beams reinforcing the structure, and drainage pipes removing groundwater, thus forming overall rigidity and anti-overturning capacity.
It improves the construction safety and stability of the foundation pit, reduces construction costs, enhances the foundation pit's resistance to sliding and overturning, and ensures rapid, simple, and adaptable construction.
Smart Images
Figure CN223937170U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to a support structure, and more particularly to a support structure for ultra-deep foundation pits under moderate weathering conditions. Background Technology
[0002] During construction, some sites are too small to allow for slope excavation, and some sites have moderately weathered soil with unstable physical and mechanical properties, posing challenges to foundation pit support. Traditional single-pile foundation support technology, when used in complex soil conditions such as moderately weathered soil environments, involves a large amount of work and is costly. It also weakens the foundation pit's resistance to sliding and overturning, failing to guarantee construction safety and affecting the normal construction of foundation pit support. To overcome these technical shortcomings, this utility model proposes a support structure for ultra-deep foundation pits under moderately weathered conditions. Utility Model Content
[0003] The technical problem to be solved by this utility model is to provide a support structure for ultra-deep foundation pits under moderate weathering conditions that is quick and easy to construct, highly safe, cost-effective, and highly adaptable.
[0004] This utility model discloses a support structure for an ultra-deep foundation pit under moderate weathering conditions, comprising steel pipe piles evenly arranged on the ground around the foundation pit to form the outline boundary of the foundation pit, with consistent spacing between each steel pipe pile; a concrete surface layer poured onto the sidewall of the foundation pit; anchor rods installed on the sidewall of the foundation pit between each steel pipe pile; a waist beam evenly arranged horizontally on the concrete surface layer and connected to the anchor rods; and a capping beam poured onto the top of the steel pipe piles.
[0005] This utility model discloses a support structure for ultra-deep foundation pits under moderate weathering conditions. The support structure also includes drainage pipes, which are inserted into the concrete surface layer and evenly arranged vertically along the concrete surface layer. A filter screen is provided at the insertion end of the drainage pipe.
[0006] This utility model discloses a support structure for an ultra-deep foundation pit under moderate weathering conditions, wherein the outlet end of the drain pipe is inclined downward at 5 degrees in the horizontal direction.
[0007] This utility model discloses a support structure for ultra-deep foundation pits under moderate weathering conditions, wherein the waist beam is a channel steel, the channel steel is provided with anchors, and the anchor rod is connected to the channel steel through the anchors.
[0008] This utility model discloses a support structure for an ultra-deep foundation pit under moderate weathering conditions, wherein the anchor rod near the side wall of the foundation pit is inclined upward at 20 degrees in the horizontal direction.
[0009] This utility model discloses a support structure for ultra-deep foundation pits under moderate weathering conditions, wherein the steel pipe piles extend into the cap beam at 2 / 3 of its height.
[0010] The difference between this utility model and the prior art lies in the support structure for an ultra-deep foundation pit under moderate weathering conditions. In this utility model, the pit sidewalls are supported by steel pipe piles and anchor cables, further reinforced by a concrete surface layer and a lintel beam. Finally, a cap beam is poured on top of the steel pipe piles to form the foundation pit retaining wall. The steel pipe piles effectively transfer loads and provide necessary lateral support to the pit sidewalls. The anchor cables, through the application of prestress, enhance the stability of the piles and increase lateral resistance. The combination of these two elements further enhances the overall rigidity and overturning resistance of the foundation pit, ensuring its safety under external loads.
[0011] The present invention will be further described below with reference to the accompanying drawings. Attached Figure Description
[0012] Figure 1 This is a schematic diagram of the support structure for an ultra-deep foundation pit under moderate weathering conditions according to this utility model.
[0013] Figure 2 This is a schematic diagram of the middle waist beam and anchor rod of this utility model fixed on the side wall of the foundation pit;
[0014] Figure 3 This is a schematic diagram of the steel pipe piles and anchor rods fixed on the side wall of the foundation pit in this utility model.
[0015] Figure 4 This is a schematic diagram of the drainage pipe fixed on the side wall of the foundation pit in this utility model;
[0016] Figure 5 This is a schematic diagram of the crown beam being cast onto the steel pipe pile in this utility model.
[0017] Figure label:
[0018] 1-Steel pipe pile; 2-Anchor cable rod; 3-Concrete surface layer; 4-Waist beam; 5-Channel steel; 6-Anchorage; 7-Cover beam; 8-Drainage pipe; 81-Filter screen. Detailed Implementation
[0019] like Figure 1 As shown, this utility model discloses a support structure for an ultra-deep foundation pit under moderate weathering conditions, comprising steel pipe piles 1, which are evenly arranged on the ground around the foundation pit to form the outline boundary of the foundation pit, and the spacing between each steel pipe pile 1 is consistent; a concrete surface layer 3, which is poured on the side wall of the foundation pit; anchor rods 2, which are set on the side wall of the foundation pit between each steel pipe pile 1; a waist beam 4, which is evenly arranged horizontally on the concrete surface layer 3 and connected to the anchor rods 2; and a cap beam 7, which is poured on top of the steel pipe piles 1.
[0020] According to the requirements, the control lines for the pile positions and holes were measured and laid out. The spacing, row spacing and center point of the steel pipe piles 1 were measured and laid out. After the pile positions were determined, the holes were drilled using the down-the-hole hammer drilling process. The hole diameter was 220mm. In order to reduce the mutual influence between adjacent pile holes, the construction process of intermittent skip drilling was adopted. The steel pipe piles 1 were miniature steel pipe piles 1. After each steel pipe pile 1 was installed into the drilled hole, pure cement grout was poured into the steel pipe to form the outline boundary of the foundation pit. Then the foundation pit was excavated.
[0021] Because the foundation soil has a layered structure from top to bottom, including layers of miscellaneous fill, strongly weathered granite gneiss, and moderately weathered granite gneiss, their stability varies. Steel pipe piles 1 provide support to the sidewalls of the foundation pit during excavation, preventing sidewall collapse. During excavation, the excavation speed and depth are strictly controlled to avoid damaging the support structure.
[0022] After the excavation of the foundation pit is completed, a concrete surface layer 3 is poured on the side wall of the foundation pit (including the area where the steel pipe pile 1 is located) to reinforce it, thereby reinforcing the side wall of the foundation pit through the concrete layer.
[0023] like Figure 1 As shown, anchor rods 2 are inserted on the sidewall of the foundation pit between every two adjacent steel pipe piles 1. The anchor rods 2 are evenly distributed in the transverse and longitudinal directions on the sidewall of the foundation pit. The anchor rods 2 are installed by drilling holes in the sidewall of the foundation pit. The prestress is applied by the anchor rods 2, which enhances the stability of the steel pipe piles 1, increases the lateral resistance, and further reinforces the sidewall of the foundation pit.
[0024] like Figure 2 As shown, the waist beam 4 is installed horizontally on the concrete surface layer 3. One waist beam 4 is installed at each row of horizontally distributed anchor rods 2. Each anchor rod 2 is fixed on the waist beam 4, which further strengthens the support structure formed by the steel pipe pile 1 and the anchor rods 2.
[0025] like Figure 1 and Figure 5 As shown, after the sidewall of the foundation pit is supported, a threaded steel support is installed at the top of the steel pipe pile 1. The threaded steel support is made of threaded steel and is connected to the top of the steel pipe pile 1 by welding or mechanical connection. The top of each steel pipe pile 1 is connected by setting the threaded steel support at the top of the steel pipe pile 1. Then, a cap beam 7 is poured with cement grout to further reinforce the steel pipe pile 1, enhance the lateral support force on the sidewall of the foundation pit, and prevent objects outside the foundation pit from sliding into the foundation pit.
[0026] like Figure 1 , 4 As shown, this utility model provides a support structure for an ultra-deep foundation pit under moderate weathering conditions. The support structure also includes a drainage pipe 8, which is inserted into the concrete surface layer 3 and evenly arranged vertically along the concrete surface layer 3. A filter screen 81 is provided at the insertion end of the drainage pipe 8, and the outlet end of the drainage pipe 8 is inclined downward at 5 degrees in the horizontal direction.
[0027] Due to the presence of groundwater in the underground soil, multiple drainage pipes 8 are evenly inserted into the concrete surface layer 3 for effective drainage. The spacing of the drainage pipes 8 is determined comprehensively based on factors such as groundwater level changes and soil permeability coefficients in the engineering geological survey report. The drainage pipes 8 are made of PVC pipes with a length of 400mm and a diameter of not less than 50mm to ensure effective penetration through the concrete surface layer 3 and a certain depth into the soil for good drainage. A filter screen 81 is installed inside the end of the drainage pipe 8 inserted into the concrete surface layer 3 to prevent soil particles from clogging the drainage pipe 8.
[0028] The drain pipes 8 are arranged vertically and evenly on the concrete surface layer 3, and the outlet end of the drain pipe is inclined downward at 5 degrees in the horizontal direction. While ensuring the drainage function, the structural damage to the concrete surface layer 3 is small, and excessive loss of soil from the side wall of the foundation pit can be avoided. The number of drain pipes 8 is not specifically limited here, and can be set according to the actual construction situation. By setting up the drain pipes 8, the groundwater and surface seepage water in the soil can be discharged in time, and the foundation pit can be prevented from collapsing due to groundwater problems.
[0029] like Figure 3 As shown, the waist beam 4 is a channel steel 5, and an anchor 6 is installed on the channel steel 5. The anchor rod 2 is connected to the channel steel 5 through the anchor 6.
[0030] The waist beam 4 is made of I-shaped channel steel 5, and an anchor 6 is set in its groove. The anchor 6 can be a bolt, a locking pin or other fastener with the same anchoring effect. A through hole is set on the channel steel 5 at the position corresponding to the anchor rod 2. The anchor rod 2 passes through the through hole of the channel steel 5 and is then firmly fixed by the anchor 6. The channel steels 5 can be welded together by steel pipes or other connecting rods to enhance the support force on the concrete surface layer 3.
[0031] This forms a robust support structure. First, the sidewalls of the foundation pit are supported by steel pipe piles 1. Then, the steel pipe piles 1 and the sidewalls of the foundation pit are reinforced by concrete surface layer 3. Next, anchor rods 2 are used to increase the lateral bearing capacity of the support structure. Then, the anchor rods 2 are fixed to the channel steel 5 to reinforce the concrete surface layer 3. Finally, the steel pipe piles 1 are fixed by pouring cap beam 7 to further enhance their lateral support capacity, ensuring the safety of the foundation pit and extending its service life.
[0032] like Figure 1 As shown, the end of anchor rod 2 near the side wall of the pit is inclined upward at 20 degrees in the horizontal direction.
[0033] In foundation pit engineering, the soil layer on the pit sidewall is subjected to lateral earth pressure, posing a risk of sliding and collapse into the pit. Anchor cable holes are drilled at an upward angle on the pit sidewall (i.e., the sidewall between two adjacent steel pipe piles 1), and anchor cables 2 are inserted into these holes. The length of the anchor cables 2 driven into the soil can vary, adjusted according to the actual construction conditions. The anchor cables 2 are inclined upward at a 20-degree angle to the horizontal. This 20-degree upward angle is based on mechanical principles and engineering experience. This angle allows the anchor cables 2 to effectively transfer tension to the stable soil when subjected to lateral earth pressure, forming an upward component force to resist the soil's tendency to slide. Simultaneously, the horizontal component force works synergistically with the steel pipe piles 1 to enhance the lateral support force of the pit sidewall. Compared to other angles, the 20-degree angle has a better effect in balancing various forces and can more effectively exert the anchoring function of the anchor cables 2. By pouring cement grout into the anchor cable holes, the anchor cable rod 2 is firmly fixed to the side wall of the foundation pit, which enhances the lateral support force of the foundation pit side wall and the steel pipe pile 1, and ensures the stability and safety of the foundation pit.
[0034] like Figure 1 As shown, steel pipe pile 1 extends into the crown beam 7 at 2 / 3 of its height.
[0035] When the steel pipe pile 1 extends into the capping beam 7 at 2 / 3 of its height, it can form a tighter and more effective connection with the capping beam 7. When the foundation pit is subjected to external loads (such as soil pressure, ground overload, etc.), the steel pipe pile 1 and the capping beam 7 can jointly bear these loads as a whole, enhance the restraining effect of the capping beam 7 on the steel pipe pile 1, improve the bending resistance of the steel pipe pile 1, and thus enhance the lateral restraint force of the steel pipe pile 1 on the side wall of the foundation pit. The steel pipe pile 1 and the capping beam 7 form a stable integral structure, improving the durability of the foundation pit support structure.
[0036] The construction process is as follows:
[0037] (1) Driving of micro steel pipe piles
[0038] The micro steel pipe pile 1 was constructed using a down-the-hole hammer drilling process, with a hole diameter of 220mm. The construction process involved intermittent skipping of the hammer, and pure cement grout was used to fill the inside of the steel pipe and the drilled hole.
[0039] (2) Pouring concrete surface layer 3
[0040] In actual construction, a single layer of steel mesh is laid, and the mesh is fixed to the sidewall of the foundation pit with driven soil nails. Shotcrete work is carried out in sections, and the spraying sequence within the same section should be from bottom to top. The specifications of cement and water used for shotcrete are the same as those for grouting materials. The concrete surface layer is sprayed in two stages, with the first and second sprays having the same thickness.
[0041] (3) Install drain pipe 8
[0042] In actual construction, a PVC drain pipe 8 with a length of 400mm and a diameter of not less than 50mm is inserted into the surface layer of the sand layer with a slope of 5 degrees (i.e., tilted downwards at 5 degrees in the horizontal direction). A filter screen 81 is installed at the bottom of the drain pipe 8 or inside the insertion end. The drain pipe 8 is fixed by sprayed concrete (i.e., fixed on the concrete surface layer 3).
[0043] (4) Installation of anchor bolt 2
[0044] Before installing anchor rod 2, remove surface contaminants, apply grease to the free section, and cover with a corrugated plastic hose or PVC pipe, securing it tightly. Ensure uniform spacing of the anchor cables in both the transverse and longitudinal directions. Drive anchor rod 2 into the anchor holes on the sidewall of the pit. Grouting of the anchor holes adopts a two-stage grouting process: the first stage is atmospheric pressure grouting, and the second stage is high pressure grouting after the first grout has initially set. Anchor rod 2 can only be tensioned and locked after its fixing strength reaches 75%. Tensioning of anchor rod 2 should be done in stages, with each stage not exceeding 20% of the design pull-out resistance value of anchor rod 2 to ensure its stability.
[0045] (5) Install waist beam 4
[0046] The waist beam 4 is a single channel steel 5. The channel steel 5 is fixedly connected to the anchor rod 2 through the anchor 6. Then, multiple parallel channel steels 5 are welded together as one piece through the connecting rod.
[0047] (6) Casting the cap beam 7
[0048] The capping beam 7 is a reinforced concrete capping beam 7. Threaded steel bars are tied to the top of each steel pipe pile 1 to form a support and connect them. The steel pipes in the micro steel pipe piles 1 penetrate to 2 / 3 of the height of the capping beam 7. Finally, the capping beam 7 is formed by pouring cement grout.
[0049] It should be noted that the terms "center", "upper", "lower", "front", "rear", "left", "right", "middle", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.
[0050] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.
[0051] The above embodiments are merely descriptions of preferred embodiments of the present utility model and are not intended to limit the scope of the present utility model. Various modifications and improvements made by those skilled in the art to the technical solutions of the present utility model without departing from the spirit of the present utility model should fall within the protection scope defined by the claims of the present utility model.
Claims
1. A support structure for an ultra-deep foundation pit under moderate weathering conditions, characterized in that: It includes steel pipe piles, which are evenly arranged on the ground around the foundation pit to form the outline boundary of the foundation pit, and the spacing between each steel pipe pile is consistent. A concrete surface layer, which is poured onto the sidewall of the foundation pit; Anchor rods are installed on the sidewalls of the foundation pit between each steel pipe pile; A waist beam, which is evenly arranged horizontally on the concrete surface and connected to the anchor rod; The capping beam is cast on top of the steel pipe pile.
2. The support structure for an ultra-deep foundation pit under moderate weathering conditions according to claim 1, characterized in that: It also includes a drain pipe, which is inserted into the concrete surface and evenly arranged vertically along the concrete surface, and a filter screen is provided at the insertion end of the drain pipe.
3. The support structure for an ultra-deep foundation pit under moderate weathering conditions according to claim 2, characterized in that: The outlet end of the drain pipe is inclined downward at 5 degrees in the horizontal direction.
4. The support structure for an ultra-deep foundation pit under moderate weathering conditions according to claim 3, characterized in that: The waist beam is a channel steel, and an anchor is provided on the channel steel. The anchor rod is connected to the channel steel through the anchor.
5. The support structure for an ultra-deep foundation pit under moderate weathering conditions according to claim 4, characterized in that: The anchor rod is inclined upward at 20 degrees in the horizontal direction at the end near the side wall of the foundation pit.
6. The support structure for an ultra-deep foundation pit under moderate weathering conditions according to claim 5, characterized in that: The steel pipe pile extends into the cap beam at 2 / 3 of its height.