A filter layer mold, drainage prism and construction method thereof

Abstract

The present application relates to the technical field of dam construction, in particular to a kind of reverse filter mould, drainage prism and its construction method, including several partitions, a pair of mutually parallel side plates and several can be detachably installed on the two side plates on pulling rod, the side of the two side plates is set up with several obliquely arranged clamping slots, the side edge of the two sides of all the partitions is respectively clamped on the clamping slot on the two side plates, all the partitions are arranged in parallel, the area between the two adjacent partitions is formed filling cavity.The reverse filter mould, drainage prism and its construction method can realize the accurate and efficient laying of the reverse filter material, significantly improve the construction quality and efficiency of the drainage prism, and enhance the overall integrity and stability of the structure.

Description

Technical Field

[0001] This invention relates to the field of dam construction technology, specifically to a filter layer mold, a drainage prism, and a construction method thereof. Background Technology

[0002] In hydraulic dam engineering, drainage prisms are one of the key structures ensuring the stability and safety of the dam body. They are typically located at the bottom of the downstream face of the dam to lower the phreatic line and prevent the dam from becoming unstable due to seepage. The core functions of drainage prisms are drainage and filtration: on the one hand, to smoothly drain seepage water from inside the dam body, and on the other hand, to prevent soil particles from being lost with the seepage water. To achieve the filtration function, the interior of the drainage prism usually needs to be equipped with a filter layer composed of materials such as fine sand, medium sand, and gravel arranged in a specific gradation and sequence.

[0003] Traditional drainage prism construction, especially the construction of the filter layer, mostly adopts manual layer-by-layer spreading and compaction. This method has many drawbacks: First, manual spreading makes it difficult to accurately control the thickness, boundaries, and gradation of each layer of filter material, resulting in unstable filtration effects and potential safety hazards; second, it is inefficient, time-consuming, and labor-intensive; third, the connection between the filter layer and masonry layers, dry-laid stone layers, etc., is often not tight enough, easily forming seepage channels and affecting the overall drainage effect. Although there are some auxiliary tools or molds for filter layer construction in existing technologies, these tools are mostly simple in structure and single in function, making it difficult to achieve precise, efficient, and integrated construction of multi-layer, multi-gradation filter materials, especially in the case of complex drainage prism structures, where it is difficult to quickly construct lateral filter layers that meet design requirements. Summary of the Invention

[0004] In order to overcome one of the shortcomings of the prior art, the present invention aims to provide a filter layer mold, a drainage prism and its construction method, which can realize the precise and efficient laying of filter layer materials, significantly improve the construction quality and efficiency of drainage prism, and enhance the integrity and stability of the structure.

[0005] To solve the above problems, the technical solution adopted by the present invention is as follows:

[0006] A reverse filter layer mold includes several partitions, a pair of parallel side plates, and several pull rods detachably mounted on the two side plates. Several inclined slots are provided on the opposite side of the two side plates. The sides of all the partitions are respectively engaged in the slots on the two side plates. All the partitions are arranged in parallel, and the area between two adjacent partitions forms a filling cavity.

[0007] Furthermore, the partition is provided with four pieces, and the four partitions, together with the two side plates, form three filling cavities.

[0008] Furthermore, each of the filling cavities is provided with a traction rod.

[0009] Furthermore, both side plates are provided with through holes, and the two ends of the pull rod respectively move through the through holes on the corresponding side plate. A nut is screwed onto one end of the pull rod that passes through the through hole, and the two nuts press the two side plates tightly against the two sides of the partition.

[0010] Furthermore, both side plates are parallelograms, and the slot is parallel to the hypotenuse of the side plate.

[0011] A drainage prism, located at the bottom of the downstream face of a dam, includes a bottom filter layer, a masonry layer, and a filter layer mold. The bottom filter layer is laid on the excavated surface at the bottom of the dam. The masonry layer is laid on the bottom filter layer, and a dry-laid stone layer is laid on the masonry layer. A lateral filter layer is connected to the masonry layer, the bottom filter layer, and the dry-laid stone layer on the side closest to the dam. The lower part of the lateral filter layer protrudes towards one side of the dam to form a prism-shaped tip. The lateral filter layer includes the filter layer mold stacked layer by layer and a filler material filled in the filter layer mold. A prism pressing layer is provided on the top of the dry-laid stone layer and the lateral filter layer. A concrete retaining wall and drainage structure are constructed at the end of the bottom filter layer away from the dam. The concrete retaining wall is connected to the bottom side of the dry-laid stone layer.

[0012] Furthermore, the filling material includes a fine sand layer, a medium sand layer, and a crushed stone layer arranged sequentially from one side of the dam body towards the dry masonry layer, wherein the thickness ratio of the fine sand layer, the medium sand layer, and the crushed stone layer is 1:1:1.4-2.

[0013] Furthermore, a mortar-grouted stone layer is also provided between the dry-laid stone layer and the lateral reverse filter layer.

[0014] Furthermore, the prism-shaped pressure layer is a concrete layer.

[0015] A method for constructing a drainage prism includes the following steps:

[0016] S100, level the dam foundation excavation surface, lay the bottom filter layer, and build a concrete retaining wall and drainage structure at the end of the bottom filter layer away from the dam body.

[0017] S200. On the side of the bottom filter layer closest to the dam body, stack a layer of filter layer molds side by side along the length of the dam body. All the partitions on the filter layer molds have a horizontal component pointing to the side of the dam body. On the side of the filter layer molds closest to the dam body, fill with rammed earth. On the side of the filter layer molds away from the dam body, fill with masonry layers and dry masonry layers outward in sequence.

[0018] S300. Fill the filling cavity of each filter layer mold with fine sand, medium and coarse sand and gravel in sequence from one side of the dam body outward; after filling is completed, remove all the partitions in each filter layer mold to complete the construction operation of one filter layer mold.

[0019] S400. On the already paved filter layer mold, continue to stack another layer of filter layer molds in the same direction along the length of the dam body. Fill the side of the filter layer mold closest to the dam body with rammed earth. On the side of the filter layer mold away from the dam body, fill the mortar-grouted stone layer and dry-laid stone layer outward in sequence. Then, follow step S300. Repeat the above operation multiple times until the construction reaches the preset height and the side of the dry-laid stone layer facing outward forms a slope.

[0020] S500. On the already laid filter layer mold, continue to stack another layer of filter layer molds side by side along the length of the dam body. All the partitions on the filter layer molds have a horizontal component facing away from the dam body. Fill the side of the filter layer molds close to the dam body with rammed earth, and fill the side of the filter layer molds away from the dam body with mortar-grouted stone layer and dry-laid stone layer in sequence. Perform the operation according to step S300. Repeat the above operation multiple times until the drainage prism construction reaches the preset height.

[0021] S600. Lay a concrete layer of a predetermined thickness on top of the dry-laid stone layer. The concrete layer completely covers the top layer of the filter layer mold. Trim the outer side of the dry-laid stone layer to complete the construction of the drainage prism.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0023] This invention provides a novel filter layer mold that utilizes detachable partitions and side plates to construct a precise filling cavity. This allows for precise positioning and constraint of each material layer of the filter layer, enabling standardized and modular construction. This significantly improves the construction accuracy and uniformity of the filter layer, avoiding the problems of inconsistent gradation and thickness caused by traditional manual laying.

[0024] The drainage prism structure of this invention utilizes the aforementioned mold to construct a lateral filter layer. The mold is used to fix each layer of the lateral filter layer, providing a shaping effect and significantly improving the integrity and stability of the filter layer. In particular, the protruding prism-shaped tip design at the bottom of the lateral filter layer effectively increases the seepage path, extends the waterline, lowers the phreatic line of the dam, and improves the seepage prevention effect. Simultaneously, the mold itself, as part of the structure, enhances the overall strength of the drainage prism.

[0025] The construction method of this invention has a clear process and is easy to operate. It enables the simultaneous and alternating construction of the filter layer, the mortar-grouted stone layer, and the dry-laid stone layer, greatly improving construction efficiency. Through a phased, variable-direction mold stacking strategy, drainage prisms with slopes and complex shapes can be efficiently constructed, ensuring construction quality, shortening the construction period, and reducing costs. This method is particularly suitable for the rapid and high-quality construction of high-standard drainage prisms in large-scale water conservancy projects.

[0026] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the structure of the filter layer mold in an embodiment of the present invention. Figure 1 ;

[0028] Figure 2 This is a schematic diagram of the structure of the filter layer mold in an embodiment of the present invention. Figure 1 ;

[0029] Figure 3 This is an exploded view of the filter layer mold in an embodiment of the present invention;

[0030] Figure 4 This is a schematic diagram of the drainage prism in an embodiment of the present invention;

[0031] Figure 5 This is a partial structural diagram of the drainage prism in an embodiment of the present invention without removing the partition.

[0032] Explanation of icon numbers:

[0033] 11. Partition; 12. Side plate; 13. Tie rod; 14. Slot; 15. Filling cavity; 16. Perforation; 17. Nut; 20. Bottom filter layer; 30. Mortar-grouted stone layer; 40. Dry-laid stone layer; 50. Lateral filter layer; 51. Prism tip; 60. Prism top layer; 70. Dam body; 80. Filler; 81. Fine sand layer; 82. Medium sand layer; 83. Crushed stone layer; 90. Concrete retaining wall; 91. Drainage structure. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of this invention clearer, the invention 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 merely illustrative and not intended to limit the invention.

[0035] See Figures 1 to 3This application first provides a filter layer mold, which includes several partitions 11, a pair of parallel side plates 12, and several pull rods 13 detachably mounted on the two side plates 12. Several inclined slots 14 are provided on the opposite side of each of the two side plates 12. The sides of all the partitions 11 are respectively engaged in the slots 14 on the two side plates 12. All the partitions 11 are arranged in parallel, and the area between two adjacent partitions 11 forms a filling cavity 15. The number of partitions 11 determines the number of filling cavities 15. For example, when there are N partitions 11, N-1 filling cavities 15 can be formed. The slots 14 on the side plates 12 are preferably arranged in parallel at equal intervals to ensure that the width of each filling cavity 15 is consistent, thereby ensuring the uniform thickness of each material layer of the filter layer.

[0036] See Figure 1 In a more specific embodiment, four partitions 11 are provided, and the four partitions 11, together with two side plates 12, form three filling cavities 15. These three filling cavities 15 can be filled with fine sand, medium sand, and gravel, respectively, to form a standard three-layer reverse filter structure. In a more preferred embodiment, each filling cavity 15 is provided with a pull rod 13. The pull rod 13 not only enhances the overall structural rigidity of the mold and prevents the side plates 12 from deforming during material filling, but also allows the pull rod 13 to pass through the filled fine sand, medium sand, and gravel. After the partitions 11 are removed, the pull rod 13 can still provide support for the side plates 12 on both sides, preventing the side plates 12 from tipping over. It can also serve as a reinforcing rib inside the molded lateral reverse filter structure, improving structural stability.

[0037] See Figure 1 and Figure 2 To enable the detachable installation of the pull rod 13 and provide a stable clamping force, in one embodiment of this application, both side plates 12 are provided with through holes 16. The two ends of the pull rod 13 respectively extend through the through holes 16 on the corresponding side plate 12. A nut 17 is screwed onto the end of the pull rod 13 extending through the through hole 16. The two nuts 17 press the two side plates 12 tightly against both sides of the partition plate 11. By tightening the nuts 17, the side plates 12 and the partition plate 11 can be firmly fixed as a whole, preventing displacement during filling and vibration of materials. When it is necessary to remove the partition plate 11, the nuts 17 can be loosened appropriately to reduce the clamping force of the side plates 12 on the partition plate 11, facilitating the smooth removal of the partition plate 11. Of course, in some embodiments, the partition plate 11 does not need to be removed; it can be part of the entire mold. In this case, the partition plate 11 is provided with several drainage holes to facilitate the free flow of water between each layer of filler.

[0038] See Figures 1 to 3To facilitate the construction of a sloping drainage prism, in one embodiment of this application, both side plates 12 are parallelograms, and the slot 14 is parallel to the hypotenuse of the side plate 12. The parallelogram design of the side plates 12 allows the top and bottom of the entire mold to form an inclination angle consistent with the dam slope when stacked. The parallelism of the slot 14 to the hypotenuse ensures that the partition 11 is also inclined after installation, thus naturally creating an inclined state for the filter material layer within the filling cavity 15, which helps guide seepage water smoothly towards the drainage structure. In other embodiments, the side plates 12 can also be rectangular or other shapes according to design requirements, and the inclination angle of the slot 14 can be adaptively adjusted according to the slope of the dam 70. In this application, the side plates 12 can be concrete slabs, which not only ensure the stability of the material structure but also provide a certain degree of permeability. Similarly, in this application, the partition 11 can be a concrete slab or a plastic grid plate.

[0039] See Figure 4 and Figure 5 This application also provides a drainage prism located at the bottom of the downstream face of the dam body 70. The drainage prism includes a bottom filter layer 20, a masonry layer 30, and a filter layer mold as described in any of the above embodiments. The bottom filter layer 20 is laid on the excavated surface at the bottom of the dam body 70, and its function is to provide preliminary filtration and drainage at the bottom; it is typically composed of well-graded sand and gravel. The masonry layer 30 is laid on the bottom filter layer 20, serving as one of the main supporting structures of the drainage prism, and has the advantages of high strength and strong erosion resistance. A dry-laid stone layer 40 is laid on the masonry layer 30, located outside the drainage prism, serving as slope protection and further drainage. The main body of the dam body 70 is constructed of rammed earth.

[0040] Specifically, a lateral filter layer 50 is connected to the side of the masonry layer 30, the bottom filter layer 20, and the dry-laid stone layer 40 near the dam body 70. That is, the lateral filter layer 50 is vertically or nearly vertically positioned on the side of the drainage prism near the dam body 70, with its bottom surface connected to the bottom filter layer 20, and its outer side connected to both the masonry layer 30 and the dry-laid stone layer 40. The main function of the lateral filter layer 50 is to intercept and drain water seeping from inside the dam body 70, while preventing the loss of soil particles from the dam body 70. The lower part of the lateral filter layer 50 protrudes to one side of the dam body 70 to form a prismatic tip 51. This prismatic tip 51 is embedded in the soil layer at the bottom of the dam body 70 or the excavated surface, effectively increasing the seepage inlet area, reducing the seepage gradient, and extending the seepage path, thereby significantly improving drainage and seepage prevention effects. In some embodiments, the bottom filter layer 20 and the lateral filter layer 50 adopt the same structural design, and the connection between them is smoothly transitioned.

[0041] Specifically, in one embodiment, the lateral filter layer 50 includes a filter layer mold stacked layer by layer and a filler 80 filling the filter layer mold. That is, the lateral filter layer 50 is formed by filling filter material into the filling cavity 15 after multiple molds are stacked vertically. The side plate 12 of the mold can be retained as part of the structure after construction, or it can be partially or completely removed. However, in this application, it is preferred to retain the side plate 12 because it can serve as a barrier and support between the filter layer and adjacent structural layers, enhancing the overall integrity.

[0042] See Figure 5 In one embodiment of this application, the filling material 80 includes a fine sand layer 81, a medium sand layer 82, and a crushed stone layer 83 arranged sequentially from one side of the dam body 70 towards the dry masonry layer 40. This arrangement, with the particle size gradually increasing from one side of the dam body 70 towards the dry masonry layer 40, is a standard reverse filtration design, effectively preventing fine soil particles from the dam body 70 from being carried out by seepage, while ensuring smooth drainage of seepage water. In a more preferred embodiment, the thickness ratio of the fine sand layer 81, the medium sand layer 82, and the crushed stone layer 83 is 1:1:1.4-2. This specific thickness ratio is the optimal ratio summarized from numerous experiments and engineering practices, ensuring good reverse filtration while considering material costs and construction efficiency. Of course, depending on the different soil types and seepage conditions of the dam body, this thickness ratio can be adjusted within a certain range. For example, the thickness ratio of the fine sand layer 81, the medium sand layer 82, and the crushed stone layer 83 can vary between 0.8-1.2:0.8-1.2:1.2-1.6.

[0043] In the above embodiment, a prism-shaped pressure layer 60 is provided on top of the dry-laid stone layer 40 and the lateral filter layer 50. The prism-shaped pressure layer 60 is used to protect the top dry-laid stone and filter layer from rainwater erosion and external damage. A concrete retaining wall 90 and a drainage structure 91 are constructed at the end of the bottom filter layer 20 away from the dam body 70. The concrete retaining wall 90 is connected to the corresponding side of the bottom of the dry-laid stone layer 40. The concrete retaining wall 90 serves as the bottom support and sealing structure on the downstream side of the drainage prism, and is connected to the drainage structure 91. It is used to concentrate and orderly discharge seepage water collected at the bottom of the drainage prism, preventing water flow from eroding and damaging the dam toe of the dam body 70. The drainage structure 91 can be a drainage pipe, drainage ditch, or other structure.

[0044] In another embodiment, to further enhance the overall strength and seepage prevention performance of the drainage prism, a mortar-grouted masonry layer 30 is also provided between the dry-laid stone layer 40 and the lateral filter layer 50. Adding a mortar-grouted masonry layer 30 makes the structure more stable and better able to resist lateral earth pressure.

[0045] In another embodiment, the prism top layer 60 is a concrete layer. Concrete layers have advantages such as high strength, good durability, and ease of construction, providing reliable top protection for the drainage prism. The thickness of this concrete layer can be determined according to design requirements, for example, 15cm-30cm. In other embodiments, the prism top layer 60 may also be made of precast concrete blocks or masonry blocks, etc.

[0046] See Figure 4 and Figure 5 This application also provides a method for constructing a drainage prism, which preferably uses the aforementioned reverse filter layer mold for construction, and specifically includes the following steps:

[0047] Step S100: Level the dam foundation excavation surface, lay the bottom filter layer 20, and construct a concrete retaining wall 90 and a drainage structure 91 at the end of the bottom filter layer 20 away from the dam body 70.

[0048] Step S200: On the side of the bottom filter layer 20 closest to the dam body 70, stack a layer of filter layer molds side by side along the length of the dam body 70. All the partitions 11 on the filter layer molds have a horizontal component pointing towards the dam body 70. Fill and compact backfill soil on the side of the filter layer molds closest to the dam body 70 to support the molds and restore the dam body shape; on the side of the filter layer molds furthest from the dam body 70, fill outwards sequentially with a masonry layer 30 and a dry-laid stone layer 40.

[0049] Step S300: In each filter layer mold, fine sand, medium-coarse sand, and gravel are sequentially filled into the filling cavity 15 along the direction from one side of the dam body 70 outwards, forming a fine sand layer 81, a medium sand layer 82, and a gravel layer 83, respectively. During filling, the filling can be done layer by layer with slight vibration to ensure compaction. After all filling cavities 15 are filled, all partitions 11 in each filter layer mold are pulled out from the slots 14 of the side plates 12 in an inclined direction upwards or laterally. After the partitions 11 are removed, the different materials in adjacent filling cavities 15 form a tight contact, together constituting a complete filter layer. At this time, the tie rods 13 and the side plates 12 remain in place, serving as supports and shaping elements. Completing the above operations completes the construction of one filter layer mold.

[0050] Step S400: On the already laid filter layer mold, continue to stack another layer of filter layer molds in the same direction along the length of the dam body 70. Fill the side of the filter layer mold closest to the dam body 70 with rammed earth, and fill the side of the filter layer mold away from the dam body 70 with mortar-grouted stone layer 30 and dry-laid stone layer 40 outwards in sequence. Then, proceed according to step S300. Repeat the above operation multiple times, that is, stack the molds layer by layer, fill backfill soil, lay mortar-grouted stone and dry-laid stone, fill filter material and remove partition 11, until the construction reaches the preset height. At this time, the outward side of the dry-laid stone layer 40 gradually forms the designed slope as the number of layers increases.

[0051] Step S500: On the already laid filter layer mold, another layer of filter layer molds is stacked side by side along the length of the dam body 70. All the partitions 11 on the filter layer molds have a horizontal component facing away from the dam body 70. On the side of the filter layer molds closest to the dam body 70, rammed earth is filled. On the side of the filter layer molds furthest from the dam body 70, masonry layer 30 and dry-laid stone layer 40 are filled outwards in sequence. Then, proceed according to step S300. Repeat the above operation multiple times, that is, continue construction layer by layer upwards until the drainage prism construction reaches the preset final height.

[0052] Step S600: Lay a concrete layer of a predetermined thickness on top of the dry-laid stone layer 40. This concrete layer is the prism top layer 60. The concrete layer completely covers the top layer of the filter layer mold to protect the top of the entire drainage prism. At the same time, trim the outer side of the dry-laid stone layer 40 to make its slope flat and beautiful, meeting the design requirements. Thus, the construction of the entire drainage prism is completed.

[0053] In step S100 of the above method, the bottom foundation of the downstream face of the dam body 70 is first excavated and compacted. Then, a layer of gravel of a predetermined thickness is laid as the bottom filter layer 20. In this application, the structure of the bottom filter layer 20 is similar to that of the lateral filter layer 50, which is also laid outward from the soil layer in sequence as a fine sand layer 81, a medium sand layer 82, and a crushed stone layer 83. The thickness can be laid according to actual needs, for example, the ratio of the three is 1:1:1.4. Subsequently, at the end of the bottom filter layer 20, i.e., the downstream side, a concrete retaining wall 90 is poured, and drainage structures 91 such as drainage pipes are pre-embedded or installed. The height of the concrete retaining wall 90 should be at least level with or higher than the top of the bottom filter layer 20 to facilitate subsequent construction. Preferably, in this application, the concrete retaining wall 90 is higher than the bottom filter layer 20, and the ratio of the height difference to the bottom filter layer 20 is between 1:1.2 and 2.

[0054] In step S300 of the above method, as a preferred embodiment, the thickness ratio of the fine sand layer 81, medium sand layer 82, and crushed stone layer 83 in the filling body 80 is 1:1:1.4-2. For example, if the total width of the filling cavity 15 is 45cm, then the fine sand layer 81 fills 15cm, the medium sand layer 82 fills 15cm, and the crushed stone layer 83 fills 20cm. During the filling process, a dedicated filling tool or funnel can be used to ensure clear boundaries between each material layer and avoid mixing.

[0055] In steps S400 and S500, to ensure construction quality, before stacking each layer of molds, the top of the side plate 12 of the lower mold should be ensured to be flat and free of debris. The side plates 12 between adjacent molds should fit tightly to prevent leakage of filling material. In step S400, the inclination direction of all partitions 11 is consistent, i.e., pointing towards the dam body 70, so that the constructed lateral filter layer 50 is inclined towards the dam body 70 as a whole. When filling backfill soil, it should be compacted in layers, and its compaction degree should not be lower than the compaction degree requirement of the corresponding part of the dam body 70. In step S500, changing the inclination direction of the partitions 11 is to construct the prismatic tip 51 protruding towards the dam body 70 at the bottom of the lateral filter layer 50. This tip can be embedded inside the dam body 70, providing better seepage prevention and support.

[0056] In step S600, the concrete layer should be poured after the dry-laid stone layer 40 and the lateral filter layer 50 have been completed and passed inspection. The concrete should be cured promptly after pouring to prevent cracking. When smoothing the slope of the dry-laid stone layer 40, protruding stones can be adjusted or tightened manually or mechanically to ensure a smooth slope.

[0057] The above embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention shall fall within the scope of protection claimed by the present invention.

Claims

1. A filter layer mold, characterized in that, It includes several partitions, a pair of parallel side plates, and several pull rods that can be detachably installed on the two side plates. Several inclined slots are provided on the opposite side of the two side plates. The sides of all the partitions are respectively locked into the slots on the two side plates. All the partitions are arranged in parallel, and the area between two adjacent partitions forms a filling cavity.

2. The filter layer mold according to claim 1, characterized in that: The partition is provided in four pieces, and the four partitions, together with the two side plates, form three filling cavities.

3. The filter layer mold according to claim 2, characterized in that: Each of the filling cavities is provided with a traction rod.

4. A filter layer mold according to claim 1, characterized in that: Both side plates have through holes, and the two ends of the pull rod respectively move through the through holes on the corresponding side plate. A nut is screwed onto one end of the pull rod that passes through the through hole, and the two nuts press the two side plates tightly against the two sides of the partition.

5. A filter layer mold according to claim 1, characterized in that: Both side plates are parallelograms, and the slot is parallel to the hypotenuse of the side plate.

6. A drainage prism located at the bottom of the downstream face of a dam, characterized in that, The dam includes a bottom filter layer, a masonry layer, and a filter layer mold as described in any one of claims 1-5. The bottom filter layer is laid on the excavated surface at the bottom of the dam body. The masonry layer is laid on the bottom filter layer. A dry masonry layer is laid on the masonry layer. A lateral filter layer is connected to the masonry layer, the bottom filter layer, and the dry masonry layer on the side closest to the dam body. The lower part of the lateral filter layer protrudes towards one side of the dam body to form a prismatic tip. The lateral filter layer includes the filter layer mold stacked layer by layer and a filler material filled in the filter layer mold. A prismatic pressing layer is provided on the top of the dry masonry layer and the lateral filter layer. A concrete retaining wall and a drainage structure are constructed at the end of the bottom filter layer away from the dam body. The concrete retaining wall is connected to the bottom side of the dry masonry layer on the corresponding side.

7. A drainage prism according to claim 6, characterized in that: The filling material includes a fine sand layer, a medium sand layer, and a crushed stone layer arranged sequentially from one side of the dam body towards the dry masonry layer, with the thickness ratio of the fine sand layer, medium sand layer, and crushed stone layer being 1:1:1.4-2.

8. A drainage prism according to claim 6, characterized in that: A mortar-grouted stone layer is also provided between the dry-laid stone layer and the lateral filter layer.

9. A drainage prism according to claim 6, characterized in that: The prism-shaped top layer is a concrete layer.

10. A method for constructing a drainage prism, characterized in that, Includes the following steps: S100, level the dam foundation excavation surface, lay the bottom filter layer, and build a concrete retaining wall and drainage structure at the end of the bottom filter layer away from the dam body. S200. On the side of the bottom filter layer closest to the dam body, stack a layer of filter layer molds side by side along the length of the dam body. All the partitions on the filter layer molds have a horizontal component pointing to the side of the dam body. On the side of the filter layer molds closest to the dam body, fill with rammed earth. On the side of the filter layer molds away from the dam body, fill with masonry layers and dry masonry layers outward in sequence. S300. Fill the filling cavity of each filter layer mold with fine sand, medium and coarse sand and gravel in sequence from one side of the dam body outward; after filling is completed, remove all the partitions in each filter layer mold to complete the construction operation of one filter layer mold. S400. On the already paved filter layer mold, continue to stack another layer of filter layer molds in the same direction along the length of the dam body. Fill the side of the filter layer mold closest to the dam body with rammed earth. On the side of the filter layer mold away from the dam body, fill the mortar-grouted stone layer and dry-laid stone layer outward in sequence. Then, follow step S300. Repeat the above operation multiple times until the construction reaches the preset height and the side of the dry-laid stone layer facing outward forms a slope. S500. On the already laid filter layer mold, continue to stack another layer of filter layer molds side by side along the length of the dam body. All the partitions on the filter layer molds have a horizontal component facing away from the dam body. Fill the side of the filter layer molds close to the dam body with rammed earth, and fill the side of the filter layer molds away from the dam body with mortar-grouted stone layer and dry-laid stone layer in sequence. Perform the operation according to step S300. Repeat the above operation multiple times until the drainage prism construction reaches the preset height. S600. Lay a concrete layer of a predetermined thickness on top of the dry-laid stone layer. The concrete layer completely covers the top layer of the filter layer mold. Trim the outer side of the dry-laid stone layer to complete the construction of the drainage prism.

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