Pile film bag earth rock cofferdam suitable for high permeable foundation

Abstract

The utility model provides a pile film bag earth and rock cofferdam suitable for a high-permeable foundation. The pile film bag earth and rock cofferdam comprises a high-strength woven bag filled earth and rock cofferdam body, a high-strength composite geomembrane bagged earth and rock slope protection and anti-seepage blanket, a geomembrane anti-seepage inclined wall, an earth and rock filling cofferdam body, a high-strength composite geomembrane bagged earth and rock slope protection, a cofferdam crest mud stone pavement, a permeable layer and the like. The upstream upstream face adopts a double-insurance combination form of a high-strength composite geomembrane bagged soil and stone anti-seepage blanket, a high-strength composite geomembrane bagged soil and stone slope protection and a geomembrane anti-seepage inclined wall, and the good water retaining, anti-seepage, anti-impact and anti-frost heaving effects are achieved. And meanwhile, the foundation adopts the steel sheet pile anti-seepage core wall, so that the foundation seepage stability problem of the cofferdam constructed on the high-permeability foundation can be effectively solved. The anti-seepage structure can be applied to various wading engineering construction scenes and has the advantages of guaranteeing the anti-seepage effect, being safe in structure, saving investment, shortening the construction period, being environment-friendly and the like.

Description

Technical Field

[0001] This utility model relates to the field of water conservancy and hydropower engineering technology, specifically to a pile membrane bag soil-rock cofferdam suitable for highly permeable foundations. Background Technology

[0002] Cofferdams are temporary water-retaining structures used in diversion projects to protect construction pits and ensure that permanent structures can be built on dry ground. Currently, common cofferdams can be classified according to the materials used, such as earth-rock cofferdams, concrete cofferdams, sheet pile cofferdams, grass-soil cofferdams, and bagged soil cofferdams, with earth-rock cofferdams being the most widely used.

[0003] Traditional earth-rock cofferdams, relying on their own weight for structural stability, are typically large in size and require ample earth and rock as filling materials. Furthermore, the inability to quickly perform underwater compaction in the early stages of construction increases investment and delays the project. Especially when constructing cofferdams on highly permeable foundations (such as sand or gravel layers), traditional earth-rock cofferdams often suffer from severe leakage due to the high permeability of the foundation, affecting the stability and water-blocking effect of the cofferdam. Current technologies often employ seepage barriers and grouting curtains for seepage prevention, but these methods involve complex construction procedures, high costs, and long construction periods, and their seepage prevention effect is limited in highly permeable foundations. Therefore, there is an urgent need for a cofferdam structure suitable for highly permeable foundations to improve seepage prevention, reduce construction difficulty and costs, and minimize the adverse ecological impacts of construction. Utility Model Content

[0004] In view of the shortcomings of the existing technology, this utility model provides a pile membrane bag soil-rock cofferdam suitable for highly permeable foundations, which can effectively solve the above problems.

[0005] The technical solution adopted in this utility model is as follows:

[0006] This utility model provides a pile-membrane bag soil-rock cofferdam suitable for highly permeable foundations, including: a high-strength woven bag soil-rock filling cofferdam body (1), a high-strength composite geomembrane bag soil-rock slope protection and seepage prevention cover (2), a geomembrane seepage prevention inclined wall (4), a soil-rock filling cofferdam body (6), a high-strength composite geomembrane bag soil-rock slope protection (7), a mud-bound stone pavement on the top of the cofferdam (8), and a permeable layer (9);

[0007] On top of the permeable layer (9), a high-strength woven bag soil and rock filling dam (1) is set up; on the upstream water-facing side of the high-strength woven bag soil and rock filling dam (1) and on top of the permeable layer (9) connected to the upstream water-facing side, a high-strength composite geomembrane bag soil and rock slope protection and seepage prevention cover (2) is laid; on the back water-facing side of the high-strength woven bag soil and rock filling dam (1), a geomembrane seepage prevention inclined wall (4) is laid.

[0008] Above the permeable layer (9) and downstream of the high-strength woven bag soil-rock filling dam (1), the soil-rock filling dam (6) is set up, one side of the soil-rock filling dam (6) is connected to the geomembrane anti-seepage inclined wall (4); the top of the soil-rock filling dam (6) is higher than the top of the high-strength woven bag soil-rock filling dam (1), and the soil-rock filling dam (6) has an upstream water-facing surface that is connected to the upstream water-facing surface of the high-strength woven bag soil-rock filling dam (1) above and below; the upstream water-facing surface of the soil-rock filling dam (6) is covered with the high-strength composite geomembrane bag soil-rock slope protection (7); the top of the soil-rock filling dam (6) is provided with the dam top mud-bound stone pavement (8).

[0009] Preferably, the high-strength woven bag soil and rock filling dam (1) includes multiple first filling units. Each first filling unit is stacked in a staggered triangular pattern to form the high-strength woven bag soil and rock filling dam (1) with a trapezoidal cross-section that is narrower at the top and wider at the bottom, with an upstream slope ratio of 1:1 to 1:2.5 and a downstream slope ratio of 1:1 to 1:1.5.

[0010] Preferably, the first filling unit includes a high-strength woven bag and a first graded soil and rock filler material filled inside the high-strength woven bag; the first filling units are connected and stacked by a first modular connecting member;

[0011] The high-strength woven bag has a three-layer structure: the outer layer is a polyester fiber or UV-resistant polypropylene material layer, the middle layer is a cross-woven high-strength nylon mesh reinforcement layer, and the inner layer is lined with a hot-pressed composite PE geomembrane; the first-grade soil and rock filler has a soil and rock particle size of 0.075mm to 10cm and a filling density of ≥1.8g / cm².

[0012] The first modular connecting component is a nylon binding bag or a transverse brace.

[0013] Preferably, the high-strength composite geomembrane bagged earth-rock slope protection and seepage-proof cover (2) includes a high-strength composite geomembrane bagged earth-rock slope protection and a high-strength composite geomembrane bagged seepage-proof cover; the high-strength composite geomembrane bagged earth-rock slope protection is laid on the upstream water-facing side of the high-strength woven bagged earth-rock filling weir (1); the high-strength composite geomembrane bagged seepage-proof cover is laid on top of the permeable layer (9).

[0014] Preferably, the high-strength composite geomembrane bagged soil and rock slope protection and seepage prevention cover (2) includes multiple second filling units. Each second filling unit is stacked in a staggered triangular pattern to form the high-strength composite geomembrane bagged soil and rock slope protection and seepage prevention cover (2) with a protection thickness of 1.0m to 3.0m and a slope ratio of 1:1.5 to 1:2.5 in the form of a parallelogram.

[0015] Preferably, the second filling unit includes a first high-strength composite geomembrane bag and a second graded soil and rock filler material filled inside the first high-strength composite geomembrane bag; each of the second filling units is connected and stacked by a second modular connecting member;

[0016] The first high-strength composite geomembrane bag has a three-layer structure, including an outer high-density polyethylene (HDPE) geomembrane layer, a middle nylon mesh reinforcement layer, and an inner LLDPE membrane geomembrane layer. The outer HDPE geomembrane layer is coated with a polyurethane UV-resistant coating with an overall thickness of 0.8 mm to 1.2 mm. The nylon mesh density of the middle nylon mesh reinforcement layer is 4 mm × 4 mm. The thickness of the inner LLDPE membrane geomembrane layer is 0.6 mm.

[0017] The particle size of the soil and rock filler material in the second grade soil and rock filler material is 0.075mm~10cm, and the filling density is ≥1.8g / cm².

[0018] The second modular connecting component consists of high-strength PP ropes pre-installed on both sides of the bag body. The ropes have a diameter of 10mm and a length of 1 / 2 bag width, and are crisscrossed in an X-shape for secure binding.

[0019] Preferably, a steel sheet pile anti-seepage core wall (3) is provided at the back slope angle of the high-strength woven bag soil and rock filling dam (1); the top of the steel sheet pile anti-seepage core wall (3) is higher than the permeable layer (9), and the bottom is embedded in the permeable layer (9);

[0020] The steel sheet pile seepage prevention core wall (3) is formed by connecting U-shaped steel sheet pile units with a groove width of 600mm, a groove depth of 140mm, and a plate thickness of 18mm through interlocking joints.

[0021] Preferably, the bottom of the geomembrane seepage-proof inclined wall (4) is connected to the top of the steel sheet pile seepage-proof core wall (3) by anchors; the geomembrane seepage-proof inclined wall (4) is a composite geomembrane with two layers of fabric and one layer of membrane, and the thickness is ≥1.5cm.

[0022] Preferably, the top width of the earth-rock filling dam (6) is ≥5m, the upstream slope ratio is 1:1 to 1:2.5, and the downstream slope ratio is 1:1 to 1:1.5;

[0023] The downstream drainage prism (5) is set at the back slope angle of the earth-rock filling weir (6); the cross-sectional form of the downstream drainage prism (5) is: top width 2m, water-facing slope ratio 1:1.5, and back slope ratio 1:1.

[0024] Preferably, the high-strength composite geomembrane bagged earth and rock slope protection (7) includes multiple third filling units. Each of the third filling units is stacked in a staggered triangular pattern to form a parallelogram cross-section of the high-strength composite geomembrane bagged earth and rock slope protection (7) with a protection thickness of 1.0m to 1.5m and a slope ratio of 1:1.5 to 1:2.5.

[0025] The third filling unit includes a second high-strength composite geomembrane bag and a third graded soil and rock filler material filled inside the second high-strength composite geomembrane bag; the third filling units are connected and stacked with each other by a third modular connecting member.

[0026] The second high-strength composite geomembrane bag has a three-layer structure, including an outer high-density polyethylene (HDPE) geomembrane layer, a middle layer of HDPE and 18-mesh glass fiber mesh hot-pressed composite reinforcement layer, and an inner LLDPE membrane geomembrane layer. The outer HDPE geomembrane layer is coated with a polyurethane UV-resistant coating with an overall thickness of 0.8mm to 1.2mm. The thickness of the HDPE and 18-mesh glass fiber mesh hot-pressed composite reinforcement layer is 1.0mm. The thickness of the inner LLDPE membrane geomembrane layer is 0.6mm.

[0027] The third-grade soil-rock filler has a soil-rock particle size of 0.075mm to 10cm and a filling density of ≥1.8g / cm².

[0028] The third modular connecting component consists of high-strength PP ropes pre-installed on both sides of the bag body. The ropes have a diameter of 10mm and a length of 1 / 2 bag width, and are tied together in an X-shape.

[0029] The pile-membrane bag soil-rock cofferdam provided by this utility model, suitable for highly permeable foundations, has the following advantages:

[0030] The upstream water-facing side employs a double-insurance combination of high-strength composite geomembrane bagged soil-rock seepage prevention paving, high-strength composite geomembrane bagged soil-rock slope protection, and geomembrane seepage prevention inclined wall. This combination effectively blocks water, prevents seepage, resists erosion, and resists frost heave. While ensuring the stability and safety of the cofferdam's seepage flow, compared to traditional earth-rock cofferdams, it optimizes the cofferdam's shape, reduces the amount of earth and rock materials used, lowers the quality requirements for cofferdam materials at the quarry, and significantly saves on project investment. Simultaneously, the foundation utilizes a steel sheet pile seepage prevention core wall, effectively solving the problem of foundation seepage stability for cofferdams built on highly permeable ground. Compared to construction techniques such as clay core wall cofferdams and paste-grouted core wall cofferdams, this structure greatly simplifies the construction process, shortens the construction period, and reduces construction costs. After construction, the recycling and reuse of the steel sheet piles further saves on project investment and reduces the adverse environmental impact caused by construction.

[0031] This utility model can be applied to various water-related engineering construction scenarios, and it has many advantages in ensuring seepage prevention, structural safety, saving investment, shortening construction period, and being environmentally friendly. Attached Figure Description

[0032] Figure 1 A cross-sectional view of a pile-membrane bag soil-rock cofferdam suitable for highly permeable foundations provided by this utility model;

[0033] Figure 2 A schematic diagram of a single steel sheet pile in the steel sheet pile seepage-proof core wall structure provided by this utility model;

[0034] Figure 3 This is an overall schematic diagram of the steel sheet pile seepage-proof core wall structure provided by this utility model.

[0035] Among them: 1-High-strength woven bag soil and rock filling dam body; 2-High-strength composite geomembrane bag soil and rock slope protection and seepage prevention paving; 3-Steel sheet pile seepage prevention core wall; 4-Geomembrane seepage prevention inclined wall; 5-Downstream drainage prism; 6-Soil and rock filling dam body; 7-High-strength composite geomembrane bag soil and rock slope protection; 8-Dam top mud-bound stone pavement; 9-Permeable layer; 10-Relatively impermeable layer. Detailed Implementation

[0036] To make the technical problems solved, technical solutions, and beneficial effects of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this utility model and are not intended to limit this utility model.

[0037] See Figures 1 to 3This utility model provides a sheet pile membrane bag earth-rock cofferdam suitable for highly permeable foundations. It is a steel sheet pile membrane bag earth-rock cofferdam structure suitable for highly permeable foundations, using geosynthetic composite materials and local materials for cofferdam construction. It includes: a high-strength woven bag earth-rock filling cofferdam body 1, a high-strength composite geomembrane bag earth-rock slope protection and seepage prevention cover 2, a geomembrane seepage prevention inclined wall 4, an earth-rock filling cofferdam body 6, a high-strength composite geomembrane bag earth-rock slope protection 7, a mud-bound stone pavement on the top of the cofferdam 8, and a permeable layer 9.

[0038] On top of the permeable layer 9, a high-strength woven bag soil-rock filling dam 1 is constructed; on the upstream water-facing side of the high-strength woven bag soil-rock filling dam 1 and on top of the permeable layer 9 connected to the upstream water-facing side, a high-strength composite geomembrane bag soil-rock slope protection and seepage-proof cover 2 is laid; on the back water-facing side of the high-strength woven bag soil-rock filling dam 1, a geomembrane seepage-proof inclined wall 4 is laid.

[0039] Above the permeable layer 9 and downstream of the high-strength woven bag soil-rock filling dam 1, the soil-rock filling dam 6 is set up, one side of which is connected to the geomembrane anti-seepage inclined wall 4; the crest of the soil-rock filling dam 6 is higher than the crest of the high-strength woven bag soil-rock filling dam 1, and the soil-rock filling dam 6 has an upstream water-facing surface that is connected to the upstream water-facing surface of the high-strength woven bag soil-rock filling dam 1; the upstream water-facing surface of the soil-rock filling dam 6 is covered with the high-strength composite geomembrane bag soil-rock slope protection 7; and the crest of the soil-rock filling dam 6 is provided with the dam crest mud-bound stone pavement 8.

[0040] A steel sheet pile anti-seepage core wall 3 is installed at the back slope angle of the high-strength woven bag soil and rock filling dam 1; the top of the steel sheet pile anti-seepage core wall 3 is higher than the permeable layer 9, and the bottom is embedded in the permeable layer 9. A downstream drainage prism 5 is installed at the back slope angle of the soil and rock filling dam 6.

[0041] The following is a detailed introduction to each structure:

[0042] (I) High-strength woven bag earth and rock filling dam body 1

[0043] The high-strength woven bag-filled earth-rock cofferdam 1 is a stable structural form that can replace the bottom protection of erosion-resistant rockfill and facilitate rapid underwater encroachment and cofferdam construction. This structural form reduces the mining and utilization of earth and rock materials, and solves the problems of underwater dumping of earth and rock materials that cannot be compacted in the early stages of cofferdam formation, resulting in the inability to quickly consolidate and compact the fill, which directly affects the construction progress and increases project investment.

[0044] The high-strength woven bag soil and rock filling dam 1 includes multiple first filling units. Each first filling unit is stacked in a staggered, triangular pattern to form the high-strength woven bag soil and rock filling dam 1 with a trapezoidal cross-section that is narrower at the top and wider at the bottom, with an upstream slope ratio of 1:1 to 1:2.5 and a downstream slope ratio of 1:1 to 1:1.5.

[0045] The first filling unit includes a high-strength woven bag and a first graded soil and rock filler material filled inside the high-strength woven bag; the first filling units are connected and stacked together by a first modular connecting member.

[0046] The high-strength woven bag has a three-layer woven structure. The outer layer is made of polyester fiber or UV-resistant polypropylene material, the middle layer is a cross-woven high-strength nylon mesh reinforcement layer with a mesh density of 5mm×5mm, and the inner layer is lined with a heat-pressed composite PE geomembrane with a thickness of 0.3mm. The fabric unit area mass is 250g / ㎡~400g / ㎡. The bag dimensions are: length 80cm~100cm, width 40cm~60cm, height 30cm~100cm. The outer surface of the bag is equipped with transverse reinforcing ribs and hanging rings, with a rib spacing of 20cm. The tensile strength of a single bag in both warp and weft directions is ≥50KN / m, and the permeability coefficient is ≤1×10. -6 cm / s.

[0047] The first-grade soil and rock filler has a particle size of 0.075mm to 10cm and a filling density of ≥1.8g / cm².

[0048] The first modular connecting component is a nylon binding bag or a transverse brace.

[0049] (II) High-strength composite geomembrane bagged earth-rock slope protection and seepage-proof covering 2

[0050] High-strength composite geomembrane bagged soil and rock slope protection and seepage prevention paving is a new type of structure with high structural performance, high structural stability, high construction efficiency, high environmental adaptability and low construction cost.

[0051] The high-strength composite geomembrane bagged earth-rock slope protection and seepage-proof cover 2 includes a high-strength composite geomembrane bagged earth-rock slope protection and a high-strength composite geomembrane bagged seepage-proof cover; the high-strength composite geomembrane bagged earth-rock slope protection is laid on the upstream water-facing side of the high-strength woven bagged earth-rock filling weir 1; the high-strength composite geomembrane bagged seepage-proof cover is laid on top of the permeable layer 9.

[0052] The high-strength composite geomembrane bagged soil and rock slope protection and seepage prevention cover 2 includes multiple second filling units. Each second filling unit is stacked in a staggered triangular pattern to form the high-strength composite geomembrane bagged soil and rock slope protection and seepage prevention cover 2 with a protection thickness of 1.0m to 3.0m and a slope ratio of 1:1.5 to 1:2.5 in the form of a parallelogram.

[0053] The second filling unit includes a first high-strength composite geomembrane bag and a second graded soil and rock filler material filled inside the first high-strength composite geomembrane bag; each of the second filling units is connected and stacked by a second modular connecting member;

[0054] The first high-strength composite geomembrane bag has a three-layer structure, manufactured using a three-layer co-extrusion process. It includes an outer high-density polyethylene (HDPE) geomembrane layer, a middle nylon mesh reinforcement layer, and an inner LLDPE membrane geomembrane layer. The outer HDPE geomembrane layer is coated with a polyurethane UV-resistant coating, with an overall thickness of 0.8mm–1.2mm. The nylon mesh density of the middle nylon mesh reinforcement layer is 4mm × 4mm. The thickness of the inner LLDPE membrane geomembrane layer is 0.6mm. The seams of the geomembrane bag are treated using double-pass hot-melt welding technology, increasing the embedded reinforcing band by 50–80mm, with a weld strength ≥ 80% of the parent material. The longitudinal tensile strength of the geomembrane bag is ≥ 35KN / m, the CBR puncture strength is ≥ 8KN, and the permeability coefficient is ≤ 1 × 10⁻⁶. -12 cm / s; Film bag dimensions: length 80cm~100cm, width 40cm~60cm, height 30cm~100cm.

[0055] The particle size of the soil and rock filler material of the second grade soil and rock filler material is 0.075mm~10cm, and the filling density is ≥1.8g / cm².

[0056] The second modular connecting component consists of high-strength PP ropes pre-installed on both sides of the bag body. The ropes have a diameter of 10mm and a length of 1 / 2 bag width, and are crisscrossed in an X-shape for secure binding.

[0057] (III) Steel Sheet Pile Anti-Seepage Core Wall 3

[0058] Sheet pile core wall 3 is a type of seepage barrier structure that can be quickly constructed and is highly safe and reliable. Multiple sheet piles are connected by interlocking joints to form a continuous seepage barrier. The sheet piles are inserted into the foundation to the impermeable layer, forming a vertical seepage barrier. This effectively solves the problems of long construction periods, high material costs, and significant environmental impact associated with traditional seepage barrier structures.

[0059] The sheet pile anti-seepage core wall 3 is formed by interconnecting U-shaped sheet pile units with a groove width of 600mm, a groove depth of 140mm, and a sheet thickness of 18mm through interlocking joints. The surface of the sheet piles is sprayed with graphene-modified epoxy resin to increase their corrosion resistance. The sheet pile anti-seepage core wall 3 has a length ≥20m or is long enough to penetrate the permeable layer and enter the relatively impermeable layer 10.

[0060] (iv) Geomembrane seepage prevention inclined wall 4

[0061] The geomembrane seepage-proof inclined wall 4 adopts a high-strength geomembrane laid obliquely along the upstream slope, providing a double-insurance seepage-proof structure compared to the geomembrane seepage-proof core wall construction method. It can effectively optimize the shape of the cofferdam, reduce the amount of soil and rock materials used for dam construction, lower the quality requirements for dam construction materials at the material yard, and significantly save on project investment.

[0062] The geomembrane seepage-proof inclined wall 4 is set at the contact position between the high-strength composite geomembrane bagged soil and rock slope protection 7 and the soil and rock filling dam 6.

[0063] The bottom of the geomembrane seepage-proof inclined wall 4 is connected to the top of the steel sheet pile seepage-proof core wall 3 by anchors, forming a continuous geomembrane seepage-proof inclined wall 4. The geomembrane seepage-proof inclined wall 4 is a composite geomembrane consisting of two layers of geotextile and one layer of geomembrane, with a thickness ≥1.5cm, and is constructed using a hot-melt welding method. The geotextile has a unit area mass of 700g / m². 3 The geomembrane seepage-proof inclined wall has a vertical seepage-proof permeability coefficient ≤ 1×10⁴. -6 cm / s.

[0064] (V) Downstream drainage prism 5

[0065] Downstream drainage prism 5 is used to prevent the loss of soil and rock materials and ensure smooth drainage, thereby reducing seepage pressure.

[0066] Downstream drainage prism 5 is set at the back slope angle of the earth-rock embankment 6; a graded crushed stone drainage strip (150mm thick, permeability coefficient ≥1×10) is provided. -2 The structure is a trapezoidal cross-section, wider at the top and narrower at the bottom, composed of a drainage prism made of boulders (cm / s) and rubble.

[0067] The downstream drainage prism 5 has the following cross-sectional shape: top width 2m, water-facing slope ratio 1:1.5, and backwater slope ratio 1:1.

[0068] (vi) Earth and rock filling dam body 6

[0069] The top width of the earth-rock filling dam 6 is ≥5m, the upstream slope ratio is 1:1 to 1:2.5, and the downstream slope ratio is 1:1 to 1:1.5.

[0070] The earth-rock filling dam body 6 adopts a layered filling and compaction process. The filling quality control requirements are: compaction degree ≥ 0.93, design dry density ≥ 1.55 g / cm³. 3 Permeability coefficient ≥1×10 -4 cm / s.

[0071] (VII) High-strength composite geomembrane bagged earth-rock slope protection 7

[0072] High-strength composite geomembrane bagged soil and rock slope protection is a new type of structure with high structural performance, high structural stability, high construction efficiency, high environmental adaptability and low construction cost.

[0073] The high-strength composite geomembrane bagged earth-rock slope protection 7 includes multiple third filling units. Each of the third filling units is stacked in a staggered triangular pattern, and is filled layer by layer to form the high-strength composite geomembrane bagged earth-rock slope protection 7 with a protection thickness of 1.0m to 1.5m and a slope ratio of 1:1.5 to 1:2.5 in the form of a parallelogram.

[0074] The third filling unit includes a second high-strength composite geomembrane bag and a third graded soil and rock filler material filled inside the second high-strength composite geomembrane bag; the third filling units are connected and stacked with each other by a third modular connecting member.

[0075] The second high-strength composite geomembrane bag has a three-layer structure, including an outer high-density polyethylene (HDPE) geomembrane layer, a middle layer of HDPE and 18-mesh glass fiber mesh hot-pressed composite reinforcement, and an inner LLDPE membrane geomembrane layer. The outer HDPE geomembrane layer is coated with a polyurethane UV-resistant coating, with an overall thickness of 0.8mm–1.2mm. The thickness of the HDPE and 18-mesh glass fiber mesh hot-pressed composite reinforcement layer is 1.0mm. The thickness of the inner LLDPE membrane geomembrane layer is 0.6mm. The joints are treated with double-pass hot-melt welding technology, increasing the embedded reinforcing band by 50–80mm, and the weld strength is ≥80% of the parent material. The longitudinal tensile strength of the geomembrane bag is ≥35KN / m, the CBR puncture strength is ≥8KN, and the permeability coefficient is ≤1×10⁻⁶. -12 cm / s; The dimensions of the second high-strength composite geomembrane bag are: length 80cm~100cm, width 50cm~100cm, height 30cm~100cm; The second high-strength composite geomembrane bag can be recycled and reused 2~3 times.

[0076] The third-grade soil-rock filler has a soil-rock particle size of 0.075mm to 10cm and a filling density of ≥1.8g / cm².

[0077] The third modular connecting component consists of high-strength PP ropes pre-installed on both sides of the bag body. The ropes have a diameter of 10mm and a length of 1 / 2 bag width, and are tied together in an X-shape.

[0078] The following describes the construction method of the pile-membrane bag soil-rock cofferdam suitable for highly permeable foundations:

[0079] I. Construction Process

[0080] Construction preparation → Site leveling → Construction of the dam body 1 with high-strength woven bag soil and rock filling during the dry season → Construction of the slope protection and seepage prevention paving of the dam body 2 with high-strength composite geomembrane bag soil and rock filling during the dry season → Construction of the steel sheet pile seepage prevention core wall 3 → Construction of the geomembrane seepage prevention inclined wall 4 → Construction of the downstream drainage prism 5 and the dam body 6 simultaneously → Construction of the slope protection of the dam body 7 with high-strength composite geomembrane bag soil and rock filling → Construction of the mud-bound stone pavement on the top of the dam 8.

[0081] II. Cofferdam Construction

[0082] This utility model adopts a phased and segmented approach for the construction of the cofferdam.

[0083] First, during the dry season, the construction area for the underwater high-strength woven bag earth-rock filling dam 1 is laid out according to the designed cofferdam axis. After removing silt and debris from the construction area, the underwater dumping and filling of high-strength woven bag earth-rock is carried out simultaneously from one or both banks towards the center of the river or lake using the vertical blocking method, forming the underwater section. When the high-strength woven bag earth-rock filling dam 1 is filled to a crest elevation ≥ the design flood level under the corresponding flood control standard during the dry season + a safety freeboard of not less than 0.5m, the construction of the high-strength woven bag earth-rock filling dam 1 is completed, and the construction of the high-strength composite geomembrane bag earth-rock slope protection and seepage prevention cover 2 begins. The bagged earth and rock materials used for filling are all taken from local earth and rock quarries, transported to the construction site by dump trucks, and after being filled, tied with hemp rope or nylon rope. Then, they are laid in layers from bottom to top using the flat laying method, with the upper and lower layers laid in a staggered triangular pattern.

[0084] III. Construction of Steel Sheet Pile Anti-Seepage Core Wall

[0085] The main construction process of the steel sheet pile anti-seepage core wall technology of this utility model is as follows: setting out and determining the construction site → site preparation → positioning and setting out to determine the steel sheet pile line → transporting the steel sheet pile to the location → moving and installing the pile driving machinery to the location → setting the guide rail → lifting the steel sheet pile → vertical positioning and clamping of the steel sheet pile → driving the steel sheet pile → installing monitoring instruments → welding and laying the composite geomembrane → cofferdam filling → project monitoring.

[0086] Considering that the steel sheet piles used are extra-long, it is proposed to use water transportation. A transportation dock will be selected in advance to transport the steel sheet piles to the construction site for use.

[0087] This invention employs a single-pile driving method for steel sheet piles, which offers fast construction speed and relatively low template height. The continuous steel sheet pile construction procedure is as follows: move to the construction platform, install the construction template, drive steel sheet piles along the template, and dismantle the construction template to move to the next working face.

[0088] Installation procedure for the construction template: drive the two support columns of the template into the foundation; use a crane to lift the frame along the support columns to the installation position and fix it; assemble the support columns and frame into a whole, adjust and calibrate its position and make it level.

[0089] After the construction template is installed, the sheet pile assembly can begin. A crane is used to lift the vibratory hammer for continuous operation. The sheet piles are pre-transported to the site on flatbed trucks and stacked in a temporary storage area. In the construction area protected by the cofferdam, a 25t long-arm crane is used to lift the ZD45 vibratory hammer and drive the sheet piles in. During driving, the vibratory hammer clamps the sheet piles together for lifting, with the sheet pile interlocks inserted into the interlocks of adjacent piles. Once the pile is stable, it is vertically vibrated and driven in the correct position. After sinking 1-2 meters, the verticality of the pile should be checked, and any deviations should be corrected promptly. If the sinking speed of the sheet pile suddenly decreases during driving, the pile driving should be stopped, and the pile should be pulled up 1 meter and driven down rapidly again.

[0090] IV. Construction of Geomembrane Anti-seepage Sloping Wall

[0091] In this invention, a composite geomembrane anti-seepage layer is laid along the backwater surface of each sub-cofferdam, and a special anchor lock is used to anchor the composite geomembrane to the exposed surface of the steel sheet pile anti-seepage core wall 3, forming a closed loop of anti-seepage layer + anti-seepage core wall.

[0092] 1) Site preparation: Before laying the membrane, the site slope is cleaned and leveled, all sharp corners and debris are removed, the under-slope is backfilled and compacted, and the rich slope is cut and leveled to provide a working surface for laying the composite geomembrane.

[0093] 2) Preparation of membrane laying method: According to the design requirements, the membrane laying method should be reasonably calculated based on the standard of reducing the number of welding seams and saving materials. In order to facilitate construction and ensure splicing quality, the composite geomembrane should be as wide as possible to reduce the amount of splicing on site. Before construction, the composite geomembrane should be cut within the unit according to the required width and length on site, and spliced ​​into blocks that meet the required size. The blocks should be rolled on steel pipes and manually transported to the working surface for laying.

[0094] 3) Installation method of geomembrane anti-seepage inclined wall 4: The composite geomembrane is laid in two parts: the lake (river) bottom laying and the slope laying. Adjacent composite geomembranes are connected in a T-shape. The lake (river) bottom laying is rolled horizontally along the axis of the lake (river channel), and the slope laying is rolled along the axis of the slope. The connection with the composite geomembrane on the river bottom is a T-shape. When laying the membrane, attention should be paid to leaving room for deformation and expansion of the anti-seepage membrane. Generally, 1% to 4% is reserved for the anti-seepage layer of artificial lakes, which is determined according to the actual site conditions, to prevent the weld seams from being torn by excessive external force when the foundation deforms.

[0095] 4) Technical requirements for geomembrane anti-seepage inclined wall 4: Laying should be carried out in dry and warm weather. In order to facilitate splicing and prevent stress concentration, the composite geomembrane is laid in a wavy loose manner with an allowance of about 1.5%. After spreading, it should be flattened in time. The composite geomembrane should fit smoothly with the slope surface without any protrusions or wrinkles. Construction personnel should wear flat cloth shoes or soft rubber shoes. It is strictly forbidden to wear nail shoes to avoid damaging the composite geomembrane. If the composite geomembrane is found to be damaged during construction, it should be repaired in time.

[0096] This utility model employs a two-layer geomembrane composite structure, with welding done using a hot-melt welding method. The splicing process includes sewing the geotextile and welding the composite geomembrane. To prevent the composite geomembrane from shifting due to strong winds after installation, the process involves simultaneous laying, welding, and securing. Before welding the composite geomembrane, the pre-existing overlap surface of the geomembrane must be cleaned; the welding machine rollers should also be cleaned. The equipment should be properly adjusted before welding. During welding, the welding machine should be kept moving at a constant speed. The weld should be inspected and tested after it has completely cooled. This process continues until the weld meets the requirements. Two welds, each 10mm wide, are spliced ​​together, with a 10mm cavity between the two welds for inspecting the weld quality.

[0097] 4) Geomembrane anchoring of geomembrane anti-seepage inclined wall 4; the upper part of the composite geomembrane can be anchored by anchoring trench or fixed by pressure strip: the anchoring trench anchoring embeds a sufficient length of composite geomembrane at the anchoring point, in the form of a concrete capping plate; the pressure strip fixing uses a nail gun in conjunction with the pressure strip and rubber gasket for sealing and fixing.

[0098] The pile-membrane bag soil-rock cofferdam for high permeability foundation provided by this utility model has the following advantages:

[0099] The upstream water-facing side employs a double-insurance combination of high-strength composite geomembrane bagged soil-rock seepage prevention paving, high-strength composite geomembrane bagged soil-rock slope protection, and geomembrane seepage prevention inclined wall. This combination effectively blocks water, prevents seepage, resists erosion, and resists frost heave. While ensuring the stability and safety of the cofferdam's seepage flow, compared to traditional earth-rock cofferdams, it optimizes the cofferdam's shape, reduces the amount of earth and rock materials used, lowers the quality requirements for cofferdam materials at the quarry, and significantly saves on project investment. Simultaneously, the foundation utilizes a steel sheet pile seepage prevention core wall, effectively solving the problem of foundation seepage stability for cofferdams built on highly permeable ground. Compared to construction techniques such as clay core wall cofferdams and paste-grouted core wall cofferdams, this structure greatly simplifies the construction process, shortens the construction period, and reduces construction costs. After construction, the recycling and reuse of the steel sheet piles further saves on project investment and reduces the adverse environmental impact caused by construction.

[0100] This utility model can be applied to various water-related engineering construction scenarios, and it has many advantages in ensuring seepage prevention, structural safety, saving investment, shortening construction period, and being environmentally friendly.

[0101] The above description is only a preferred embodiment of the present utility model. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present utility model, and these improvements and modifications should also be considered within the protection scope of the present utility model.

Claims

1. A pile-membrane bag soil-rock cofferdam suitable for highly permeable foundations, characterized in that, include: High-strength woven bag soil and rock filling dam body (1), high-strength composite geomembrane bag soil and rock slope protection and seepage prevention cover (2), geomembrane seepage prevention inclined wall (4), soil and rock filling dam body (6), high-strength composite geomembrane bag soil and rock slope protection (7), dam top mud-bound stone pavement (8) and permeable layer (9); On top of the permeable layer (9), a high-strength woven bag soil and rock filling dam (1) is set up; on the upstream water-facing side of the high-strength woven bag soil and rock filling dam (1) and on top of the permeable layer (9) connected to the upstream water-facing side, a high-strength composite geomembrane bag soil and rock slope protection and seepage prevention cover (2) is laid; on the back water-facing side of the high-strength woven bag soil and rock filling dam (1), a geomembrane seepage prevention inclined wall (4) is laid. Above the permeable layer (9) and downstream of the high-strength woven bag soil-rock filling dam (1), the soil-rock filling dam (6) is set up, one side of the soil-rock filling dam (6) is connected to the geomembrane anti-seepage inclined wall (4); the top of the soil-rock filling dam (6) is higher than the top of the high-strength woven bag soil-rock filling dam (1), and the soil-rock filling dam (6) has an upstream water-facing surface that is connected to the upstream water-facing surface of the high-strength woven bag soil-rock filling dam (1) above and below; the upstream water-facing surface of the soil-rock filling dam (6) is covered with the high-strength composite geomembrane bag soil-rock slope protection (7); the top of the soil-rock filling dam (6) is provided with the dam top mud-bound stone pavement (8).

2. A pile-membrane bag soil-rock cofferdam suitable for highly permeable foundations according to claim 1, characterized in that, The high-strength woven bag earth-rock filling dam (1) includes multiple first filling units. Each first filling unit is stacked in a staggered triangular pattern to form a trapezoidal cross-section with a narrow upper and wide lower section, with an upstream slope ratio of 1:1 to 1:2.5 and a downstream slope ratio of 1:1 to 1:1.

5.

3. A pile-membrane bag soil-rock cofferdam suitable for highly permeable foundations according to claim 2, characterized in that, The first filling unit includes a high-strength woven bag and a first-grade soil and rock filler material filled inside the high-strength woven bag; the first filling units are connected and stacked by a first modular connecting member; The high-strength woven bag has a three-layer structure: the outer layer is a polyester fiber or UV-resistant polypropylene material layer, the middle layer is a cross-woven high-strength nylon mesh reinforcement layer, and the inner layer is lined with a hot-pressed composite PE geomembrane; the first-grade soil and rock filler has a soil and rock particle size of 0.075mm to 10cm and a filling density of ≥1.8g / cm². The first modular connecting component is a nylon binding bag or a transverse brace.

4. A pile-membrane bag soil-rock cofferdam suitable for highly permeable foundations according to claim 1, characterized in that, The high-strength composite geomembrane bagged earth-rock slope protection and seepage-proof cover (2) includes a high-strength composite geomembrane bagged earth-rock slope protection and a high-strength composite geomembrane bagged seepage-proof cover; the high-strength composite geomembrane bagged earth-rock slope protection is laid on the upstream water-facing side of the high-strength woven bagged earth-rock filling weir (1); the high-strength composite geomembrane bagged seepage-proof cover is laid on top of the permeable layer (9).

5. A pile-membrane bag soil-rock cofferdam suitable for highly permeable foundations according to claim 1, characterized in that, The high-strength composite geomembrane bagged soil and rock slope protection and seepage prevention cover (2) includes multiple second filling units. Each second filling unit is stacked in a staggered triangular pattern to form a parallelogram cross-section of 1.0m to 3.0m with a slope ratio of 1:1.5 to 1:2.

5.

6. A pile-membrane bag soil-rock cofferdam suitable for highly permeable foundations according to claim 5, characterized in that, The second filling unit includes a first high-strength composite geomembrane bag and a second graded soil and rock filler material filled inside the first high-strength composite geomembrane bag; each of the second filling units is connected and stacked by a second modular connecting member; The first high-strength composite geomembrane bag has a three-layer structure, including an outer high-density polyethylene (HDPE) geomembrane layer, a middle nylon mesh reinforcement layer, and an inner LLDPE membrane geomembrane layer. The outer HDPE geomembrane layer is coated with a polyurethane UV-resistant coating with an overall thickness of 0.8 mm to 1.2 mm. The nylon mesh density of the middle nylon mesh reinforcement layer is 4 mm × 4 mm. The thickness of the inner LLDPE membrane geomembrane layer is 0.6 mm. The particle size of the soil and rock filler material in the second grade soil and rock filler material is 0.075mm~10cm, and the filling density is ≥1.8g / cm². The second modular connecting component consists of high-strength PP ropes pre-installed on both sides of the bag body. The ropes have a diameter of 10mm and a length of 1 / 2 bag width, and are crisscrossed in an X-shape for secure binding.

7. A pile-membrane bag soil-rock cofferdam suitable for highly permeable foundations according to claim 1, characterized in that, A steel sheet pile anti-seepage core wall (3) is provided at the back slope angle of the high-strength woven bag soil and rock filling dam (1); the top of the steel sheet pile anti-seepage core wall (3) is higher than the permeable layer (9), and the bottom is embedded in the permeable layer (9); The steel sheet pile seepage prevention core wall (3) is formed by connecting U-shaped steel sheet pile units with a groove width of 600mm, a groove depth of 140mm, and a plate thickness of 18mm through interlocking joints.

8. A pile-membrane bag soil-rock cofferdam suitable for highly permeable foundations according to claim 7, characterized in that, The bottom of the geomembrane seepage-proof inclined wall (4) is connected to the top of the steel sheet pile seepage-proof core wall (3) by anchors; the geomembrane seepage-proof inclined wall (4) is a composite geomembrane with two layers of fabric and one layer of membrane, and the thickness is ≥1.5cm.

9. A pile-membrane bag soil-rock cofferdam suitable for highly permeable foundations according to claim 1, characterized in that, The top width of the earth-rock embankment (6) is ≥5m, the upstream slope ratio is 1:1 to 1:2.5, and the downstream slope ratio is 1:1 to 1:1.5; The downstream drainage prism (5) is set at the back slope angle of the earth-rock filling weir (6); the cross-sectional form of the downstream drainage prism (5) is: top width 2m, water-facing slope ratio 1:1.5, and back slope ratio 1:

1.

10. A pile-membrane bag soil-rock cofferdam suitable for highly permeable foundations according to claim 1, characterized in that, The high-strength composite geomembrane bagged earth and rock slope protection (7) includes multiple third filling units. Each of the third filling units is stacked in a staggered triangular pattern, and is filled layer by layer to form a parallelogram cross-section of the high-strength composite geomembrane bagged earth and rock slope protection (7) with a protection thickness of 1.0m to 1.5m and a slope ratio of 1:1.5 to 1:2.

5. The third filling unit includes a second high-strength composite geomembrane bag and a third graded soil and rock filler material filled inside the second high-strength composite geomembrane bag; the third filling units are connected and stacked with each other by a third modular connecting member. The second high-strength composite geomembrane bag has a three-layer structure, including an outer high-density polyethylene (HDPE) geomembrane layer, a middle layer of HDPE and 18-mesh glass fiber mesh hot-pressed composite reinforcement layer, and an inner LLDPE membrane geomembrane layer. The outer HDPE geomembrane layer is coated with a polyurethane UV-resistant coating with an overall thickness of 0.8mm to 1.2mm. The thickness of the HDPE and 18-mesh glass fiber mesh hot-pressed composite reinforcement layer is 1.0mm. The thickness of the inner LLDPE membrane geomembrane layer is 0.6mm. The third-grade soil-rock filler has a soil-rock particle size of 0.075mm to 10cm and a filling density of ≥1.8g / cm². The third modular connecting component consists of high-strength PP ropes pre-installed on both sides of the bag body. The ropes have a diameter of 10mm and a length of 1 / 2 bag width, and are tied together in an X-shape.

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