Building deep foundation pit edge protection structure
By setting up a water guide channel and protective enclosure at the top of the pit, the problem of impact of mud and water mixture and water erosion on the edge protection structure of the pit-within-a-pit was solved, and the interception of mud and sand and drainage of water were achieved, thus improving the safety and protection effect of the pit-within-a-pit.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- CHINA CONSTR SEVENTH BUREAU SOUTHWEST CONSTR CO LTD
- Filing Date
- 2025-05-28
- Publication Date
- 2026-06-05
AI Technical Summary
Existing pit-within-a-pit edge protection structures are insufficient to effectively cope with the impact of mud-water mixtures and water erosion from the pit above, leading to structural failure and safety risks.
A water guide channel and protective enclosure are set up at the top of the foundation pit. A waterproof layer is laid in the water guide channel and a water guide pipe is buried. The permeable backfill layer fills the water guide channel. The protective enclosure consists of a pressure foot, a protective frame and a net. The net is set in layers to block mud and sand and separate solid and liquid. Water is discharged through the water guide pipe.
It effectively prevents silt from entering the pit-within-a-pit area, achieves solid-liquid separation, reduces the erosion of the pit-within-a-pit by the mud-water mixture, and improves the safety of edge protection and drainage reliability.
Smart Images
Figure CN224325792U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of foundation pit construction technology, specifically to an edge protection structure for deep foundation pits in buildings. Background Technology
[0002] During the construction of large foundation pits, it is often necessary to set up local excavation areas inside the main foundation pit, such as foundation caps, sump pits, pile joint treatment, or underground pipeline pre-laying operations. These local deep excavation areas are usually called "pits within pits". Because their excavation locations are mostly inside the main foundation pit operation area, the surrounding space is narrow and the soil is frequently disturbed, making them one of the areas on the construction site most prone to problems such as edge slippage, water backflow, and personnel accidentally stepping on them.
[0003] Especially when encountering rainfall or groundwater exposure, the slope above the main foundation pit is prone to surface soil slippage, forming a muddy mixture of slipped soil and rainwater, which quickly accumulates to the upper edge of the pit or even the bottom of the pit under the action of gravity.
[0004] Currently, edge protection for pit-within-pit construction often employs temporary structures. These measures primarily serve as warnings and area demarcation, with limited structural strength and interception capabilities, making them ineffective against the impact of fluid mud-water mixtures. Furthermore, these structures typically lack effective filtration and drainage mechanisms. When mud-water accumulates at the edge, it is highly susceptible to overflow, leakage, or localized concentrated erosion, causing erosion and water loss, edge subsidence, and localized collapse. This not only undermines the foundation stability of the protective structure, making it more prone to failure, but also poses collateral risks to surrounding work areas, equipment, and personnel.
[0005] Therefore, it is necessary to study a protective structure for the edge of a deep foundation pit. Utility Model Content
[0006] Therefore, the purpose of this utility model is to provide a deep foundation pit edge protection structure that can effectively solve the problem that existing pit-within-pit edge protection structures are unable to effectively cope with the impact of mud and water mixtures from the upper foundation pit and the erosion of accumulated water.
[0007] To achieve the above objectives, the technical solution adopted by this utility model is as follows:
[0008] A deep foundation pit edge protection structure includes a foundation pit, a protective enclosure, a waterproof layer, a water conduit, and a permeable backfill layer;
[0009] A water guide channel is provided around the upper part of the foundation pit, and a waterproof layer is provided on the inner wall of the water guide channel.
[0010] The water pipe is buried in the upper part of the foundation pit. One end of the water pipe passes through the waterproof layer and connects to the water channel, while the other end of the water pipe extends to the drainage ditch at the bottom of the foundation pit.
[0011] The protective fence includes pressure feet, a protective frame, and a barrier net;
[0012] The pressure foot is fixedly installed at the bottom of the water guide channel and above the waterproof layer;
[0013] The protective frame is vertically fixed to the press foot and extends upward to form a water guide groove;
[0014] The protective frame is equipped with an interception net on its side;
[0015] The permeable backfill layer is laid in the water channel to fill the water channel, and the intercepting net extends downward into the permeable backfill layer.
[0016] Furthermore, the water guiding channel is stepped, and the bottom of the channel includes a central bottom surface and stepped surfaces on both sides of the central bottom surface. The waterproof layer is continuously laid on the central bottom surface, and the two left and right sides of the waterproof layer adhere to the channel wall and extend upward to the stepped surfaces.
[0017] Furthermore, the left and right sides of the waterproof layer are fixedly connected to the step surface by anchors.
[0018] Furthermore, the interception net includes a first interception net and a second interception net. The first interception net is set on the side of the protective frame away from the foundation pit, and the second interception net is set on the side of the protective frame closer to the foundation pit. The mesh size and rigidity of the first interception net are both larger than those of the first interception net.
[0019] Furthermore, the distance between the bottom of the protective frame and the side of the pressure foot closer to the pit is less than the distance between the bottom of the protective frame and the side of the pressure foot farther from the pit.
[0020] Furthermore, a geotextile layer is continuously laid on the top of the foundation pit, and the geotextile layer is located above the permeable backfill layer.
[0021] Furthermore, the upper and lower ends of the interception net are fixedly connected to the top and bottom of the protective frame, respectively.
[0022] The beneficial effects of the above technical solution are:
[0023] This invention features a water-guiding channel installed at the top of the foundation pit. The protective enclosure utilizes a structure where the footing and protective frame are integrated. The footing is fixed to the bottom of the water-guiding channel, and the intercepting net effectively blocks mud and sand, thus preventing mud and sand from entering the pit-within-a-pit area and contaminating the work space or burying structures. A waterproof layer is laid on the inner wall of the water-guiding channel, and a water-guiding pipe connected to the bottom drainage ditch is embedded. A permeable backfill layer is placed within the water-guiding channel, ensuring structural leveling while providing the channel with permeability and drainage capabilities. This allows water after solid-liquid separation in the mud-water mixture to quickly permeate into the water-guiding pipe, effectively separating the intercepted mud-water mixture and guiding the water downwards. This effectively prevents erosion and softening caused by water accumulation and seepage in the accumulated mud and sand. It effectively addresses the problems of mud-water impact and water accumulation erosion at the edge of the pit-within-a-pit caused by landslides or rainwater erosion from the upper foundation pit, significantly improving the safety of edge protection and drainage reliability. Attached Figure Description
[0024] Figure 1 This is a cross-sectional schematic diagram of the present invention;
[0025] Figure 2 Enlarged view of the details of the protective fence;
[0026] Figure 3 for Figure 2 Right view of the protective fence.
[0027] Attached diagram labels: 1 for foundation pit, 2 for protective enclosure, 3 for waterproof layer, 4 for water pipe, 5 for permeable backfill layer, 6 for water channel, 7 for drainage ditch, 8 for anchor, 9 for geotextile layer, 201 for pressure foot, 202 for protective frame, 203 for interception net, 204 for first interception net, 205 for second interception net, 601 for central bottom surface, 602 for stepped surface. Detailed Implementation
[0028] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments:
[0029] This embodiment aims to provide a deep foundation pit edge protection structure, which is mainly used to protect the upper edge of the pit within a pit during deep foundation pit construction. It addresses the problem that existing pit within a pit edge protection structures are difficult to effectively cope with the impact of mud and water mixtures and water erosion from the foundation pit above.
[0030] A deep foundation pit edge protection structure, such as Figure 1 The structure includes a foundation pit 1, a protective enclosure 2, a waterproof layer 3, a water pipe 4, and a permeable backfill layer 5. In this embodiment, the foundation pit 1 refers to a pit within a pit, that is, the foundation pit 1 is located inside a larger, deeper foundation pit, and the upper part of the foundation pit 1 is the bottom of the larger, deeper foundation pit.
[0031] A water guide channel 6 is provided around the upper part of the foundation pit 1. A waterproof layer 3 is provided on the inner wall of the water guide channel 6. In this embodiment, the waterproof layer 3 is made of 1.5mm thick HDPE waterproof membrane, which is laid in the water guide channel 6 to facilitate recycling and removal. In other embodiments, if a longer-term reliable or even semi-permanent structure is desired, the waterproof layer 3 can be formed by applying mortar.
[0032] The water pipe 4 is buried in the upper part of the foundation pit 1. One end of the water pipe 4 passes through the waterproof layer 3 and connects to the water channel 6. The other end of the water pipe 4 extends to the drainage ditch 7 at the bottom of the foundation pit 1 to drain the water in the water channel 6 to the drainage ditch 7. The drainage ditch 7 is a drainage structure that is conventionally set at the bottom of the foundation pit 1 in the construction process of the foundation pit 1, and will not be described in detail here.
[0033] like Figure 2 and Figure 3 The protective enclosure 2 includes a footrest 201, a protective frame 202, and a netting 203. The protective enclosure 2 must be positioned at a safe distance from the edge of the pit 1 according to design requirements. If the water channel 6 is deep or causes significant disturbance to the upper part of the pit 1, it is necessary to ensure that the water channel 6 maintains a safe distance from the edge of the pit 1 to guarantee construction safety.
[0034] The foot 201 is fixed at the bottom of the water guide channel 6 by anchor rods and above the waterproof layer 3. The anchor rods pass through the waterproof layer 3 and enter the soil above the foundation pit 1 to fix the foot 201. The anchor rods are not easily eroded by water, which makes the foot 201 more stable and can also reinforce the upper part of the foundation pit 1. The anchor rods should be recyclable and the position where the anchor rods pass through the waterproof layer 3 should be sealed.
[0035] The protective frame 202 is vertically fixed on the pressure foot 201 and extends upward to form a water guide groove 6. The protective frame 202 includes a frame structure made of welded and spliced uprights and crossbars, which is used to resist the impact of mud and water mixture.
[0036] The protective frame 202 is equipped with an interception net 203 on its side. Specifically, the interception net 203 includes a first interception net 204 and a second interception net 205. The first interception net 204 is located on the side of the protective frame 202 away from the foundation pit 1, and the second interception net 205 is located on the side of the protective frame 202 closer to the foundation pit 1. The mesh size and rigidity of the first interception net 204 are both larger than those of the first interception net 204. The first interception net 204 is made of wire mesh and is used for initial interception of the mud-water mixture, reducing the impact force of the mud-water mixture. The second interception net 205 is made of geotextile mesh and is used for secondary interception of the mud-water mixture, ensuring that the mud and sand are intercepted. The interception net 203 mainly intercepts mud and sand, allowing water to pass through, thereby reducing the frontal load of the mud-water fluid impact force on the surface of the interception net 203 and improving the stability of the protective enclosure 2.
[0037] The upper and lower ends of the first intercepting net 204 and the second intercepting net 205 are fixedly connected to the top and bottom of the protective frame 202, respectively. The middle parts of the first intercepting net 204 and the second intercepting net 205 are tied and fixed to the middle part of the protective frame 202 by steel wire.
[0038] The permeable backfill layer 5 is laid in the drainage channel 6 to fill the drainage channel 6 and to compact and fix the waterproof layer 3. The intercepting net 203 extends downward into the permeable backfill layer 5. The permeable backfill layer 5 is mainly made of gravel, which can isolate silt and sand but allows water to seep down to the bottom of the drainage channel 6. The water targeted here is mainly the residual water in the silt mixture after interception, to prevent it from accumulating and seeping down and affecting the soil structure above the foundation pit 1.
[0039] To facilitate the recycling and removal of the permeable backfill layer 5, the permeable backfill layer 5 can also be filled with pre-packaged gravel. If the permeable backfill layer 5 is too heavy, it may cause a pile-up on the top of the foundation pit 1 and affect the stability of the foundation pit 1. In this case, it is necessary to increase the safe distance between the water guide channel 6 and the edge of the foundation pit 1 according to the actual situation.
[0040] Furthermore, the water channel 6 is stepped, with its bottom including a central bottom surface 601 and stepped surfaces 602 on both sides of the central bottom surface 601. The waterproof layer 3 is continuously laid on the central bottom surface 601, and its two left and right sides extend upwards to the stepped surfaces 602, adhering to the channel walls, to facilitate compaction and fixation of the waterproof layer 3 by the permeable backfill layer 5. The left and right sides of the waterproof layer 3 are fixedly connected to the stepped surfaces 602 by anchors 8 to ensure that the edges of the waterproof layer 3 are fixed.
[0041] Furthermore, the distance between the bottom of the protective frame 202 and the side of the pressure foot 201 closest to the pit 1 is less than the distance between the bottom of the protective frame 202 and the side of the pressure foot 201 furthest from the pit 1, so that when mud and sand accumulate on the side of the pressure foot 201 furthest from the pit 1, the gravity of the mud and sand can be used to enhance the stability of the protective enclosure 2.
[0042] A geotextile layer 9 is continuously laid on the top of the foundation pit 1. The geotextile layer 9 is located above the permeable backfill layer 5 to facilitate the removal of mud and sand accumulated on the permeable backfill layer 5.
Claims
1. A protective structure for the edge of a deep foundation pit, characterized in that: This includes the foundation pit, protective fencing, waterproof layer, drainage pipes, and permeable backfill layer; A water guide channel is provided around the upper part of the foundation pit, and a waterproof layer is provided on the inner wall of the water guide channel. The water pipe is buried in the upper part of the foundation pit. One end of the water pipe passes through the waterproof layer and connects to the water channel, while the other end of the water pipe extends to the drainage ditch at the bottom of the foundation pit. The protective fence includes pressure feet, a protective frame, and a barrier net; The pressure foot is fixedly installed at the bottom of the water guide channel and above the waterproof layer; The protective frame is vertically fixed to the press foot and extends upward to form a water guide groove; The protective frame is equipped with an interception net on its side; The permeable backfill layer is laid in the water channel to fill the water channel, and the intercepting net extends downward into the permeable backfill layer.
2. The edge protection structure for deep foundation pits in construction according to claim 1, characterized in that: The water guide channel is stepped, and the bottom of the channel includes a central bottom surface and stepped surfaces on both sides of the central bottom surface. The waterproof layer is continuously laid on the central bottom surface, and the two left and right sides of the waterproof layer adhere to the channel wall and extend upward to the stepped surfaces.
3. The edge protection structure for deep foundation pits in construction according to claim 2, characterized in that: The left and right sides of the waterproof layer are fixedly connected to the step surface by anchors.
4. The edge protection structure for deep foundation pits in construction according to claim 1, characterized in that: The interception net includes a first interception net and a second interception net. The first interception net is set on the side of the protective frame away from the foundation pit, and the second interception net is set on the side of the protective frame closer to the foundation pit. The mesh size and rigidity of the first interception net are both larger than those of the first interception net.
5. The edge protection structure for deep foundation pits in construction according to claim 1, characterized in that: The distance between the bottom of the protective frame and the side of the pressure foot closest to the pit is less than the distance between the bottom of the protective frame and the side of the pressure foot furthest from the pit.
6. The edge protection structure for deep foundation pits in construction according to claim 1, characterized in that: A geotextile layer is continuously laid on the top of the foundation pit, and the geotextile layer is located above the permeable backfill layer.
7. The edge protection structure for deep foundation pits in construction according to claim 1, characterized in that: The upper and lower ends of the interception net are fixedly connected to the top and bottom of the protective frame, respectively.