Method for preventing water seepage in upper water stagnation area of sand layer slope

Abstract

The application discloses a kind of sand layer slope upper layer stagnant water area anti-seepage treatment method, belong to foundation pit engineering support technical field;The method steps are as follows: first, transverse block, vertical layer to water seepage area;From stagnant water area bottom, short steel bar is hit into with hand hammer, and integral support is formed by welding;Small slope is formed by cleaning sand layer above horizontal steel bar;Lay nylon net, steel sheet net and press sand bag to form filter system;After arranging sand bag, cycle construction upper layer, finally, lay steel sheet net and weld and daub cement mortar, the lowest layer is provided with drain hole.The method does not need large equipment, adapts narrow space, can give consideration to anti-seepage, drainage and support stability, can efficiently process stagnant water on sand layer slope upper layer, guarantee construction efficiency and slope safety, reduce engineering cost.

Description

Technical Field

[0001] This invention relates to the field of foundation pit engineering support technology, specifically a method for preventing seepage in the perched water area of ​​a sandy slope. Background Technology

[0002] In the construction of municipal roads and highway bridge foundation pits, soil nailing walls are widely used due to their economic efficiency, especially in northern regions where construction is often carried out under conditions of no water or dewatering. However, when working around old residential areas or in areas with dense underground pipelines, localized stagnant water in the upper layer can easily cause sand flow, leading to obstruction of slope protection construction, reduced efficiency, and increased costs. Using dewatering wells for treatment presents challenges in project scheduling and delays, and some construction sites cannot accommodate drilling rigs due to space constraints. Therefore, there is an urgent need for an emergency seepage prevention technology that does not require large equipment. Existing slope seepage treatment methods have obvious defects: some schemes rely on large-scale dewatering equipment, which cannot be implemented in narrow sites; some schemes only focus on slope sealing and have not formed a systematic operation mode of layering and block division, which is prone to overall instability due to local water pressure accumulation; a few layered treatment technologies lack targeted reverse filter structure design, which can easily carry out sand particles during the drainage process, causing slope erosion, and it is difficult to balance timeliness and support stability. Summary of the Invention

[0003] The present invention aims to solve the above problems, thereby providing a method for preventing seepage in the upper layer of stagnant water area of ​​sand slope without the need for large mechanical equipment and suitable for narrow construction spaces.

[0004] The technical solution adopted by the present invention to solve the aforementioned problem is as follows: A method for preventing seepage in the perched water area of ​​a sandy slope is carried out according to the following steps: S1. Area division: The area of ​​sand slope with upper layer water retention and seepage is divided into horizontal blocks and vertical layers. The thickness of the vertical layer is determined according to the severity of seepage and sand flow. S2. Reinforcement Layout: Short steel bars of the same specifications as the soil nailing wall slope reinforcement are used. Starting from the bottom of the upper water-retaining area, the steel bars are driven into the lowest layer by hand hammer in the order of vertical first and then horizontal. The steel bars are welded together at the intersections immediately. The steel bars between each block are also welded to form an overall support structure. S3. Slope cleaning: Clean the sand layer above the horizontal reinforcement. The cleaning area includes the triangular area formed between the top of the adjacent upper layer and the depth of the horizontal reinforcement in the longitudinal direction of 1 / 2. This exposes part of the horizontal reinforcement and forms a small slope above the horizontal reinforcement. S4. Laying of filter layer: Nylon mesh and steel mesh are laid on the top of the exposed horizontal steel bars and on the slope surface of the small slope. The nylon mesh is attached to the slope surface of the small slope, and the steel mesh is covered on the outside of the nylon mesh. Sandbags are pressed on the outside of the steel mesh to form a multi-layer filter system. S5. Surface treatment: Smooth the outside of the sandbags to match the slope surface. After the first layer is completed, repeat the next layer construction until the entire seepage area is treated. Then, lay steel mesh on the outside of the sandbags again and weld the steel mesh to the intersection of the reinforcing bars in each layer. Use cement mortar with the same strength grade as the soil nailing wall slope protection to apply the surface, and set drainage holes when constructing the lowest layer.

[0005] Furthermore, in S1, the vertical layer thickness is less than or equal to 600mm. When water seepage and sand flow are severe, the layer thickness is reduced by increasing the reinforcement, and controlled between 150mm and 200mm. The layer thickness is flexibly adjusted according to the actual situation of water seepage and sand flow, so that the layer treatment is more in line with the on-site working conditions and avoids the problem that a uniform thickness is difficult to adapt to areas with different degrees of severity.

[0006] Furthermore, in S4, the nylon mesh is laid in two layers, using 80-120 mesh nylon mesh; this more effectively blocks sand particles while ensuring normal water infiltration and drainage, reducing the loss of sand particles with water during drainage, maintaining the stability of the internal structure of the slope, and preventing voids from appearing inside the slope due to sand loss.

[0007] Furthermore, in S5, a filter pipe is inserted into the drain hole, and the base of the filter pipe is wrapped with geotextile; this further filters sand particles in the water and prevents sand particles from being lost with the water.

[0008] Furthermore, a water guide channel is installed at the bottom of the slope, and a water collection pit is dug at the bottom of the slope. The water flowing out of the drainage hole is guided into the water collection pit through the water guide channel, and is cleaned regularly by a drainage pump installed in the water collection pit; this avoids water accumulation at the bottom of the slope, reduces water soaking of the soil at the bottom of the slope, and reduces the risk of slope instability due to softening of the soil at the bottom.

[0009] The present invention, which adopts the above technical solution, has the following prominent features compared with the prior art: The method described in this invention does not rely on large mechanical equipment. The simple operation of driving in short steel bars with a hand hammer is perfectly suited to confined construction spaces such as those around old residential areas and areas with dense underground pipelines. This solves the problem of traditional dewatering wells being unable to be installed due to site limitations, significantly reducing construction scheduling difficulty and ensuring project progress. Secondly, it adopts a systematic treatment mode of horizontal segmentation and vertical layering, combining vertical and then horizontal steel bar placement and welding into an integral support structure. This addresses areas with varying degrees of seepage and quicksand severity, preventing overall instability caused by localized water pressure accumulation and improving slope stability. Thirdly, by clearing the slope surface to form small slopes, combined with a multi-layered filter system consisting of nylon mesh, steel mesh, and sandbags, it achieves effective seepage prevention while preventing sand particles from being carried out by drainage, thus preventing slope erosion. Simultaneously, the cement mortar finish and drainage hole installation balance seepage prevention, drainage, and support strength, ensuring an efficient balance between construction timeliness and slope safety in emergency situations, reducing project costs, and overcoming the shortcomings of existing methods such as single-layer sealing or inadequate layered treatment. Attached Figure Description

[0010] Figure 1 This is a schematic diagram of the main structure of an embodiment of the present invention; The markings in the diagram are: 1. Upper stagnant water area, 2. Slope bottom, 3. Vertical steel reinforcement, 4. Horizontal steel reinforcement, 5. Small slope, 6. Sandbag, 7. Slope, 8. Water diversion channel, 9. Water collection pit. Detailed Implementation

[0011] The present invention will be further described below with reference to embodiments, which are intended only to provide a better understanding of the invention. Therefore, the examples given do not limit the scope of protection of the present invention.

[0012] See Figure 1 A method for preventing seepage in the perched water area of ​​a sandy slope is carried out according to the following steps: S1. Area division: The area of ​​the sand slope 7 where the upper layer of water seepage occurs, namely the upper water seepage area 1, is divided into horizontal blocks and vertical layers. The thickness of the vertical layer is determined according to the severity of seepage and sand flow. S2. Reinforcement Layout: Short steel bars with the same specifications as the soil nailing wall slope reinforcement are used. Starting from the bottom of the upper water-stagnant area 1, the steel bars are driven into the lowest layer by hand hammer in the order of vertical first and horizontal second. The vertical reinforcement is set as vertical steel bar 3, and the horizontal reinforcement is set as horizontal steel bar 4. The steel bars are welded together at the intersection. The steel bars between each block are also welded to form an overall support structure. S3. Slope cleaning: Clean the sand layer above the horizontal steel bar 4. The cleaning range includes the triangular area formed between the top of the adjacent upper layer and the depth of the horizontal steel bar 4 in the longitudinal direction, so that the horizontal steel bar 4 is partially exposed and a small slope 5 is formed above the horizontal steel bar 4. S4. Laying of filter layer: Nylon mesh and steel mesh are laid above the exposed horizontal steel bars 4 and on the slope surface of the small slope 5. The nylon mesh is attached to the slope surface of the small slope 5, and the steel mesh is covered on the outside of the nylon mesh. Sandbags 6 are pressed on the outside of the steel mesh to form a multi-layer filter system. S5. Surface treatment: Smooth the outside of sandbags 6 to match the slope surface of slope 7. After this layer treatment is completed, repeat the upper layer construction until the entire upper water-stagnant area 1 is treated. Then, lay steel mesh on the outside of sandbags 6 again and weld the steel mesh to the intersection of each layer of reinforcing bars. Use cement mortar with the same strength grade as the soil nailing wall slope protection to apply the surface, and set drainage holes when constructing the lowest layer. The vertical layer thickness is less than or equal to 600mm. When the seepage and sand flow are severe, the layer thickness is reduced by increasing the vertical reinforcement 3 and horizontal reinforcement 4, and controlled between 150mm and 200mm. The layer thickness is flexibly adjusted according to the actual seepage and sand flow in the upper stagnant water area 1, so that the layer treatment is more in line with the on-site working conditions and avoids the problem that a uniform thickness is difficult to adapt to areas with different degrees of severity. The nylon netting is laid in two layers, using 80-120 mesh nylon netting. At the small slope 5, the nylon netting more effectively blocks sand particles while ensuring normal water infiltration and drainage, reducing the loss of sand particles with water during drainage, maintaining the stability of the internal structure of slope 7, and preventing voids from appearing inside slope 7 due to sand loss. A filter pipe is inserted into the drainage hole, and the base of the filter pipe is wrapped with geotextile; during the drainage process, the sand particles in the water are further filtered to prevent the sand particles from being lost with the water and to ensure the integrity of the soil inside the slope. A water guide channel 8 is installed at the bottom of slope 7, i.e., slope bottom 2, and a water collection pit 9 is dug at the bottom of slope 2. Water flowing out of the drainage hole is guided into the water collection pit 9 through the water guide channel 8, and is cleaned regularly by a drainage pump installed in the water collection pit 9; this prevents water from accumulating at the bottom of slope 2, reduces water soaking of the soil at the bottom of slope 7, and reduces the risk of slope 7 becoming unstable due to softening of the soil at the bottom.

[0013] The method described in this invention does not rely on large mechanical equipment. The simple operation of driving in short steel bars with a hand hammer is perfectly suited to confined construction spaces such as those around old residential areas and areas with dense underground pipelines. This solves the problem of traditional dewatering wells being unable to be installed due to site limitations, significantly reducing construction scheduling difficulty and ensuring project progress. Secondly, it adopts a systematic treatment mode of horizontal segmentation and vertical layering, combining vertical and then horizontal steel bar placement and welding into an integral support structure. This addresses areas with varying degrees of seepage and quicksand severity, preventing overall instability caused by localized water pressure accumulation and improving slope stability. Thirdly, by clearing the slope surface to form small slopes, combined with a multi-layered filter system consisting of nylon mesh, steel mesh, and sandbags, it achieves effective seepage prevention while preventing sand particles from being carried out by drainage, thus preventing slope erosion. Simultaneously, the cement mortar finish and drainage hole installation balance seepage prevention, drainage, and support strength, ensuring an efficient balance between construction timeliness and slope safety in emergency situations, reducing project costs, and overcoming the shortcomings of existing methods such as single-layer sealing or inadequate layered treatment.

[0014] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of the present invention. All equivalent changes made based on the description and drawings of the present invention are included within the scope of the present invention.

Claims

1. A method for preventing seepage in the perched water area of ​​a sandy slope, characterized in that, Follow these steps: S1. Area division: The area of ​​sand slope with upper layer water retention and seepage is divided into horizontal blocks and vertical layers. The thickness of the vertical layer is determined according to the severity of seepage and sand flow. S2. Reinforcement Layout: Short steel bars of the same specifications as the soil nailing wall slope reinforcement are used. Starting from the bottom of the upper water-retaining area, the steel bars are driven into the lowest layer by hand hammer in the order of vertical first and then horizontal. The steel bars are welded together at the intersections immediately. The steel bars between each block are also welded to form an overall support structure. S3. Slope cleaning: Clean the sand layer above the horizontal reinforcement. The cleaning area includes the triangular area formed between the top of the adjacent upper layer and the depth of the horizontal reinforcement in the longitudinal direction of 1 / 2. This exposes part of the horizontal reinforcement and forms a small slope above the horizontal reinforcement. S4. Laying of filter layer: Nylon mesh and steel mesh are laid on the top of the exposed horizontal steel bars and on the slope surface of the small slope. The nylon mesh is attached to the slope surface of the small slope, and the steel mesh is covered on the outside of the nylon mesh. Sandbags are pressed on the outside of the steel mesh to form a multi-layer filter system. S5. Surface treatment: Smooth the outside of the sandbags to match the slope surface. After the first layer is completed, repeat the next layer construction until the entire seepage area is treated. Then, lay steel mesh on the outside of the sandbags again and weld the steel mesh to the intersection of the reinforcing bars in each layer. Use cement mortar with the same strength grade as the soil nailing wall slope protection to apply the surface, and set drainage holes when constructing the lowest layer.

2. The method for preventing seepage in the perched water area of ​​a sandy slope according to claim 1, characterized in that: In S1, the vertical layer thickness is less than or equal to 600 mm. When water seepage and sand flow are severe, the layer thickness is reduced by increasing the reinforcement, and controlled between 150 mm and 200 mm.

3. The method for preventing seepage in the perched water area of ​​a sandy slope according to claim 1, characterized in that: In S4, the nylon mesh is laid in two layers, using 80-120 mesh nylon mesh.

4. The method for preventing seepage in the perched water area of ​​a sandy slope according to claim 1, characterized in that: In S5, a filter pipe is inserted into the drainage hole, and the root of the filter pipe is wrapped with geotextile.

5. The method for preventing seepage in the perched water area of ​​a sandy slope according to claim 1, characterized in that: A water guide channel is installed at the bottom of the slope, and a water collection pit is dug at the bottom of the slope. The water flowing out of the drainage hole is guided into the water collection pit through the water guide channel, and is cleaned regularly by a drainage pump installed in the water collection pit.

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