A pile drainage and gravel reverse filtration drainage system for interlayer water in foundation pit

Abstract

The utility model discloses a gravel reverse filtration drainage system for interlayer stagnant water of foundation pit, including: foundation pit, the four around of foundation pit is provided with intercepts and drains, is provided with horizontal bellows in intercepts and drains, is seted up with a plurality of first water inlet on horizontal bellows, first water sump is seted up in the position of foundation pit inside near foundation pit left side, second water sump is seted up in the position of foundation pit inside near foundation pit right side, all are provided with sandless well pipe in first water sump and second water sump, the horizontal intercepts and drains also are provided with between the intercepts and drains of foundation pit left side above first water sump, the horizontal intercepts and drains also are provided with between the intercepts and drains of foundation pit right side above second water sump. The utility model discloses through setting up the intercepts and drains of section U shape and its inside horizontal bellows, and set up first water inlet on bellows, effectively gathered from the interlayer stagnant water of interlayer seepage of fender, and its set up first water inlet effectively prevented fine particle sandy soil with water inflow drainage system.

Description

Technical Field

[0001] This utility model relates to the field of foundation pit drainage technology, specifically to a pile-to-pile drainage and gravel reverse filtration system for drainage of water stuck between foundation pit layers. Background Technology

[0002] During the construction of open-cut foundation pits for subway stations, if the groundwater level is high, dewatering measures are typically required to lower the water level to a certain depth below the foundation before excavation can proceed. However, when there are soil interfaces with significantly different permeability coefficients (such as the boundary between medium-fine sand and clay layers), traditional dewatering wells struggle to form effective dewatering funnels, leading to frequent interlayer water stagnation. This stagnant water seeps out from between the retaining piles, easily causing sand loss and cavity formation in the soil behind the piles, thus affecting the stability of the foundation pit support system and posing a serious threat to construction safety. Currently, the common treatment method is grouting to stop the water, but this often damages the external dewatering wells during construction, leading to reduced or even ineffective dewatering. Furthermore, grouting is difficult to manage in terms of time and cost, introducing significant uncertainty to the project. Therefore, there is an urgent need for an efficient, reliable, and economical interlayer water stagnation drainage technology to ensure the smooth implementation of foundation pit projects in water-rich strata. Utility Model Content

[0003] The purpose of this invention is to provide a pile-to-pile drainage and gravel back-filter drainage system for impounded water in foundation pits, in order to solve the problems mentioned in the background art.

[0004] To achieve the above objectives, this utility model provides a pile-to-pile drainage and gravel back-filter drainage system for interlayer water retention in foundation pits, comprising: a rectangular foundation pit, a drainage ditch arranged around the foundation pit, the drainage ditch having a U-shaped cross-section, a horizontal corrugated pipe arranged inside the drainage ditch, and multiple first water inlets opened on the horizontal corrugated pipe. The water collection pit includes a first water collection pit and a second water collection pit. The first water collection pit is located inside the foundation pit near the left side of the foundation pit, and the second water collection pit is located inside the foundation pit near the right side of the foundation pit. Both the first and second water collection pits are equipped with sand-free well pipes. A transverse intercepting drainage ditch is also provided between the top of the first water collection pit and the intercepting drainage ditch on the left side of the foundation pit, and a transverse intercepting drainage ditch is also provided between the top of the second water collection pit and the intercepting drainage ditch on the right side of the foundation pit.

[0005] In a preferred embodiment, a horizontal corrugated pipe is also provided in the transverse intercepting drainage ditch, and a gravel layer is provided above the horizontal corrugated pipe, with voids provided in the gravel layer.

[0006] In a preferred embodiment, the outer wall of the sand-free well pipe is provided with a plurality of second water inlet holes, and the outer side of the sand-free well pipe is provided with a plurality of vertical corrugated pipes, and the vertical corrugated pipes are provided with a plurality of third water inlet holes.

[0007] In a preferred embodiment, the upper surface of the sump is lower than the lower surface of the drainage ditch.

[0008] In a preferred embodiment, multiple retaining piles are installed around the outside of the foundation pit, and the width of the drainage ditch is 500 mm.

[0009] In a preferred embodiment, sidewalls are provided above the perimeter of the foundation pit, and a steel mesh is provided on the sidewalls. The steel mesh is closely attached to the sidewalls and is fixedly connected to the sidewalls by a hanging steel mesh. A pre-reserved notch is provided at the lower end of the steel mesh, and a cement mortar layer is provided on the steel mesh.

[0010] In a preferred embodiment, a drainage hose is provided at the reserved gap, the lower end of the drainage hose is placed in the intercepting drainage ditch, and a dense mesh net is provided on the outside of the drainage hose.

[0011] In a preferred embodiment, a water pump is installed in the sump.

[0012] In a preferred embodiment, the first water inlet and the third water inlet have the same diameter, and the diameter of the first water inlet and the third water inlet is larger than the diameter of the second water inlet.

[0013] Compared with the prior art, the beneficial effects of this utility model are: 1. This utility model effectively collects the interlayer water seeping from between the retaining piles by setting up a U-shaped intercepting and drainage ditch and its internal horizontal corrugated pipe, and opening a first water inlet hole on the corrugated pipe, thereby realizing the orderly guidance of the scattered water. In addition, the first water inlet hole effectively prevents fine sand from flowing into the drainage system with the water.

[0014] 2. By setting a gravel layer filled with gaps above the horizontal corrugated pipe in the transverse intercepting drainage ditch, a highly efficient reverse filter drainage layer is formed. This structure allows water to flow smoothly while effectively preventing fine sand particles from flowing into the drainage system with the water, ensuring the long-term effectiveness of the drainage process and avoiding system failure due to siltation.

[0015] 3. By installing sand-free well pipes with second inlet holes on the outer walls in the first and second water collection pits, and installing vertical corrugated pipes with third inlet holes on their periphery, the water collection area and infiltration efficiency of the water collection facility are greatly increased. This enables the rapid collection of groundwater drawn from the intercepting drainage ditch and its flow into the water collection pit, significantly improving the water collection and drainage capacity of the entire system. Attached Figure Description

[0016] Figure 1 This is a schematic cross-sectional view of the base drainage system of this utility model; Figure 2 This is a schematic diagram of the drainage treatment for the water stagnation point between the sidewall layers of this utility model; Figure 3This is a detailed drawing of the first water-collecting pit of this utility model.

[0017] Explanation of reference numerals in the attached drawings: 1-Foundation pit, 2-Interception ditch, 3-Horizontal corrugated pipe, 4-First sump, 5-Second sump, 6-Sand-free well pipe, 7-Horizontal interception ditch, 8-Vertical corrugated pipe, 9-Retaining pile. 10-Steel mesh, 11-Hanging steel mesh, 12-Dense mesh, 13-Drainage hose. Detailed Implementation

[0018] The technical solutions in the embodiments of this utility model will be clearly and completely described below. All other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this utility model.

[0019] Example 1: like Figures 1 to 3 As shown, the present invention provides a pile-to-pile drainage and gravel back-filter drainage system for interlayer water retention in foundation pits, comprising: a foundation pit (1), the foundation pit (1) being rectangular, a drainage ditch (2) being provided around the foundation pit (1), the drainage ditch (2) having a U-shaped cross section, the drainage ditch (2) having a width of 500 mm, a horizontal corrugated pipe (3) being provided inside the drainage ditch (2), and multiple first water inlets being provided on the horizontal corrugated pipe (3). The water collection pit has its upper surface lower than the lower surface of the intercepting drainage ditch (2). The water collection pit includes a first water collection pit (4) and a second water collection pit (5). The first water collection pit (4) is located in the foundation pit (1) near the left side of the foundation pit (1), and the second water collection pit (5) is located in the foundation pit (1) near the right side of the foundation pit (1). Both the first water collection pit (4) and the second water collection pit (5) are equipped with sand-free well pipes (6). Multiple second water inlets are opened on the outer wall of the sand-free well pipes (6). Multiple vertical corrugated pipes (8) are arranged around the outer side of the sand-free well pipes (6). Multiple third water inlets are opened on the vertical corrugated pipes (8). The diameters of the first water inlets and the third water inlets are the same, and the diameters of the first water inlets and the third water inlets are larger than the diameters of the second water inlets. A water pump is installed in the water collection pit.

[0020] A transverse intercepting drainage ditch (7) is also provided between the first water collection pit (4) and the intercepting drainage ditch (2) on the left side of the foundation pit (1). A transverse intercepting drainage ditch (7) is also provided between the second water collection pit (5) and the intercepting drainage ditch (2) on the right side of the foundation pit (1). A horizontal corrugated pipe (3) is also provided in the transverse intercepting drainage ditch (7). A gravel layer is provided above the horizontal corrugated pipe (3), and there are gaps in the gravel layer.

[0021] Multiple retaining piles (9) are installed around the outside of the foundation pit (1). Side walls are set above the perimeter of the foundation pit (1). A steel mesh (10) is installed on the side walls. The steel mesh (10) is installed close to the side walls. The steel mesh (10) is fixedly connected to the side walls by a hanging steel mesh (11). A reserved gap is set at the lower end of the steel mesh (10). A drainage hose (13) is set at the reserved gap. The lower end of the drainage hose (13) is set in the intercepting drainage ditch (2). A dense mesh (12) is set on the outside of the drainage hose (13). A cement mortar layer is set on the steel mesh (10).

[0022] Example 2: The following describes how to use this utility model: Step 1: Excavate the foundation pit (1), and then excavate a U-shaped drainage ditch (2) around the rectangular foundation pit (1). Lay a horizontal corrugated pipe (3) with multiple first water inlets in the ditch, and finally backfill with gravel to ensure that the water inlets are unobstructed. This step forms a primary drainage channel around the foundation pit, which efficiently collects the seeping interlayer water through the first water inlets on the horizontal corrugated pipe (3) and initially guides it.

[0023] Step 2: Inside the foundation pit (1), near the left and right sides, excavate and construct the first sump pit (4) and the second sump pit (5) respectively, ensuring that the height of their openings is lower than the bottom height of the surrounding intercepting drainage ditch (2). This step utilizes the elevation difference to form a stable gravity flow, allowing the groundwater collected in the intercepting drainage ditch (2) to automatically and quickly flow into the sump pit, creating favorable conditions for subsequent centralized pumping.

[0024] Step 3: Vertically install sand-free well pipe (6) in the first water collection pit (4) and the second water collection pit (5). The outer wall of the pipe has multiple second water inlet holes. Then, drive multiple vertical corrugated pipes (8) around the sand-free well pipe (6). The pipe walls have third water inlet holes.

[0025] Step 4: Connect the first sump (4) to the intercepting drainage ditch (2) on the left side of the foundation pit, and connect the second sump (5) to the intercepting drainage ditch (2) on the right side of the foundation pit. Excavate a transverse intercepting drainage ditch (7). Lay a perforated horizontal corrugated pipe (3) in the ditch and backfill it to form a gravel layer with gaps. This step constructs a dedicated water conveyance channel connecting the perimeter of the foundation pit and the sump, and combines drainage and reverse filtration functions. The gravel layer ensures that the water flows smoothly into the horizontal corrugated pipe (3) in the transverse intercepting drainage ditch (7) while effectively preventing the inflow of fine particles of silt and preventing system blockage.

[0026] Step 5: Lay a steel mesh (10) on the side walls around the foundation pit (1) and secure it firmly with reinforcing steel bars (11). Leave a gap at the lower end of the steel mesh (10) and install a drainage hose (13) with a dense mesh (12) wrapped around its outer side at the gap. Lead the lower end of the hose into the intercepting drainage ditch (2). This step will directly guide the small amount of water seeping from the side walls of the foundation pit into the main drainage system through the drainage hose (13).

[0027] Step Six: Install water pumps in the first and second water collection pits (4) to continuously pump the collected groundwater to the outside of the foundation pit. This step provides the final power guarantee for the entire drainage system. By mechanically draining the water, the accumulation of stagnant water between layers is completely eliminated, providing a dry and safe working surface for subsequent foundation pit excavation and structural construction, thus ensuring the progress and safety of the project.

[0028] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A pile-to-pile drainage and gravel back-filtration system for perched water in foundation pits, characterized in that: include: The foundation pit (1) is rectangular. A drainage ditch (2) is provided around the foundation pit (1). The drainage ditch (2) has a U-shaped cross section. A horizontal corrugated pipe (3) is provided inside the drainage ditch (2). Multiple first water inlets are provided on the horizontal corrugated pipe (3). The water collection pit includes a first water collection pit (4) and a second water collection pit (5). The first water collection pit (4) is located in the foundation pit (1) near the left side of the foundation pit (1), and the second water collection pit (5) is located in the foundation pit (1) near the right side of the foundation pit (1). Both the first water collection pit (4) and the second water collection pit (5) are equipped with sand-free well pipes (6). A transverse intercepting drainage ditch (7) is also provided between the top of the first water collection pit (4) and the intercepting drainage ditch (2) on the left side of the foundation pit (1), and a transverse intercepting drainage ditch (7) is also provided between the top of the second water collection pit (5) and the intercepting drainage ditch (2) on the right side of the foundation pit (1).

2. The pile-to-pile drainage and gravel back-filter system for perched water in foundation pits according to claim 1, characterized in that: The transverse drainage ditch (7) is also equipped with a horizontal corrugated pipe (3), and a gravel layer is provided above the horizontal corrugated pipe (3), with voids in the gravel layer.

3. The pile-to-pile drainage and gravel back-filter system for perched water in foundation pits according to claim 2, characterized in that: The outer wall of the sand-free well pipe (6) is provided with multiple second water inlet holes, and multiple vertical corrugated pipes (8) are provided around the outer side of the sand-free well pipe (6). Multiple third water inlet holes are provided on the vertical corrugated pipes (8).

4. The pile-to-pile drainage and gravel back-filter system for perched water in foundation pits according to claim 3, characterized in that: The upper surface of the water collection pit is lower than the lower surface of the intercepting drainage ditch (2).

5. The pile-to-pile drainage and gravel back-filter system for perched water in foundation pits according to claim 4, characterized in that: The foundation pit (1) is surrounded by multiple retaining piles (9), and the drainage ditch (2) is 500 mm wide.

6. The pile-to-pile drainage and gravel back-filter system for perched water in foundation pits according to claim 5, characterized in that: The foundation pit (1) is provided with side walls above all four sides, and a steel mesh (10) is provided on the side walls. The steel mesh (10) is closely attached to the side walls. The steel mesh (10) and the side walls are fixedly connected by hanging steel bars (11). A reserved notch is provided at the lower end of the steel mesh (10). A cement mortar layer is provided on the steel mesh (10).

7. The pile-to-pile drainage and gravel back-filter system for perched water in foundation pits according to claim 6, characterized in that: A drainage hose (13) is provided at the reserved gap. The lower end of the drainage hose (13) is placed in the intercepting drainage ditch (2). A dense mesh net (12) is provided on the outside of the drainage hose (13).

8. The pile-to-pile drainage and gravel back-filter system for perched water in foundation pits according to claim 7, characterized in that: A water pump is installed in the sump.

9. The pile-to-pile drainage and gravel back-filter system for perched water in foundation pits according to claim 8, characterized in that: The first and third water inlets have the same diameter, and the diameter of the first and third water inlets is larger than that of the second water inlet.

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