FOUNDATION OF A PRECAUTIONARY SEWAGE WELL

Abstract

This utility model relates to the construction of underground engineering structures, specifically to prefabricated manhole foundations, and is intended for use in the construction of external utility networks for various purposes, primarily sewer, water, drainage, and stormwater drainage systems. The design provides a reliable support structure for the manhole, supporting operational loads and providing connection to shaft rings and pipelines. The prefabricated sewer manhole foundation comprises a side wall with a flange and a bottom. The outer surface of the side wall is provided with stiffening ribs in the form of annular ridges intersecting with longitudinal ridges, forming a regular mesh structure covering at least the side wall. The bottom is flat, with a flange extending beyond the outer surface of the side wall, and contains radial stiffening ribs in the form of radial ridges.This ensures an increase in the annular and spatial rigidity of the structure, an increase in the friction force and anchoring capacity relative to the ground, a reduction in material consumption and a simplification of the manufacturing technology, a reduction in the volume of concrete work during installation, as well as an increase in the accuracy and speed of installation, ensuring the coaxial installation of shaft rings without additional operations.

Description

[0001] This utility model relates to the construction of underground engineering structures, specifically precast manhole foundations, and is intended for use in the construction of external utility networks for various purposes, primarily sewer, water, drainage, and stormwater systems. The design ensures the formation of a reliable support structure for the manhole, supporting operational loads and ensuring connection with shaft rings and pipelines.

[0002] A polymer well is known (RU230698U1, published 12 / 17 / 2024), consisting of a base, a shaft, a cone and a telescopic part, in which a flange is made along the upper edge of the base for connection with the shaft, on the upper and lower edges of which there are connecting flanges, along the lower edge of the cone there is a connecting flange for connection with the shaft, in the upper part of the cone there is a round hole for installing a telescopic part, which is a cylindrical shell with a seat designed along the upper edge for installing a ceiling, wherein the base, shaft and cone are fastened together with plastic wedge clamps covering wedge protrusions made along the perimeter of the flanges, and plastic pins installed in holes made on the flanges, while all parts of the well are connected to each other with sealing rings made of elastic material.

[0003] A well base is known (RU220607U1, published 09.25.2023), including a body and a bottom, wherein annular ribs are made on the outer surface of the body, and vertical protrusions with a U-shaped cross-section and a flange located in the lower part of the body and connected to the bottom are made on the inner surface of the body.

[0004] Also known is a drainage well for wastewater treatment (RU199539U1, published 09 / 07 / 2020), characterized by the fact that it is made using seamless technology from low-density polyethylene in the form of a solid truncated cone with perforations for water drainage along the side surface, and transversely located annular stiffening ribs are made on the side surface.

[0005] The disadvantages of known solutions are: insufficient ring stiffness under lateral soil pressure, especially in waterlogged and heaving soils; the presence of internal vertical protrusions and flanging, complicating hydraulics and creating sediment stagnation zones; the need to increase the wall thickness or use additional materials to achieve the required strength; difficulty of manufacture due to internal cavities and protrusions; low anchoring capacity relative to the ground, requiring massive concrete counterweights to prevent floating; the absence of centering elements when connecting to shaft rings, which increases the labor intensity of installation; known corrugated shells use only ring stiffeners, which limits spatial rigidity and resistance to longitudinal bending; insufficient anchorage efficiency in the ground, which does not allow for reliable resistance to floating without additional counterweights;lack of design capability for precise and quick assembly with overlying elements without manual alignment.

[0006] The technical result achieved by implementing the claimed technical solution is expressed in an increase in the annular and spatial rigidity of the structure.

[0007] Additionally, it provides an increase in friction force and anchoring capacity relative to the ground, which helps prevent floating, a reduction in material consumption and simplification of manufacturing technology, a reduction in the volume of concrete work during installation, as well as an increase in the accuracy and speed of installation, ensuring coaxial installation of shaft rings without additional operations.

[0008] To achieve the specified technical result, a base for a prefabricated sewer well is proposed, containing a side wall with a flange and a bottom, wherein on the outer surface of the side wall there are stiffening ribs in the form of annular ridges intersecting with longitudinal ridges and jointly forming a regular mesh structure covering the side wall, and the bottom is made flat, with an edge protruding beyond the outer surface of the side wall, and contains radial stiffening ribs made in the form of radial ridges.

[0009] The foundation, which includes a sidewall and bottom, is designed to support vertical and horizontal loads from the soil and overlying wall rings, as well as to ensure the well's interior is sealed. In this technical solution, the term "foundation" refers to a single-piece molded component consisting of a sidewall and bottom. The foundation is typically cylindrical or conical, expanding toward the top, which facilitates removal from the mold during rotational molding and promotes structural stability during backfilling. The foundation is manufactured using a single-piece rotational molding method from polypropylene, polyethylene, or unplasticized polyvinyl chloride.

[0010] The sidewall has an integral flange at its top. The outer surface of the base sidewall features a regular mesh structure of intersecting annular and longitudinal ribs, covering at least its cylindrical portion. In this particular case, the mesh structure of the outer ribbing extends across the entire height of the sidewall, from the bottom to the flange. In this technical solution, a "rib" refers to a localized depression, groove, or protrusion formed on the surface of a part by plastic deformation (ribbing), without removing material, allowing for the formation of stiffening ribs of varying orientation. This design increases annular and longitudinal rigidity without increasing wall thickness, as well as creating a developed contact surface with the ground.

[0011] The flange is designed for a tight and centered connection to shaft rings. The flange is formed at the top of the sidewall as an annular thickening containing a sealing groove for a rubber seal and holes for tie bolts. The sealing groove can be rectangular, trapezoidal, or semicircular, ensuring reliable compression of the seal when tightening the flanges. The bolt holes are evenly spaced around the flange circumference, their number and diameter being selected to accommodate the axial forces from tightening and soil pressure. The flange can be equipped with a centering element in the form of an annular shoulder or groove, interacting with a mating element on the shaft ring. This design ensures automatic alignment of the elements, eliminates the need for manual alignment, and increases installation speed.

[0012] The bottom serves as the well's support structure, transferring the load from the sidewall and shaft to the soil foundation and preventing groundwater infiltration and well submergence in waterlogged soils. The bottom is flat with a flange extending beyond the outer surface of the sidewall. The flange is a flat, annular shelf, integral with the bottom and oriented perpendicular to the well axis. This flange increases the bearing surface on the soil and creates additional resistance to pullout by clamping the soil. The flange width can range from 10 to 100 mm, depending on the well diameter and design loads. The flange thickness is equal to the bottom thickness or increased by local thickening. The bottom and flange are molded integrally with the sidewall, without gaps or welds. This design ensures the stability of the well on the ground foundation and reduces the risk of uneven settlement.

[0013] Stiffeners increase the load-bearing capacity of the sidewall and bottom while using minimal material. On the sidewall, the stiffeners are formed by annular ridges (horizontal) and longitudinal ridges (vertical), intersecting at right angles or at another specified angle, forming closed cells of a rectangular, square, or diamond shape. The annular ridges encircle the sidewall along the perimeter, while the longitudinal ridges run along the generatrix. At the intersections, the ridges are structurally united due to the continuity of the material during molding. The depth and width of the ridges are selected to ensure rigidity and manufacturability; typical values ​​are: depth 10-100 mm, width 10-100 mm. The spacing between the annular ridges can be constant, for example, 50-500 mm, or variable for local reinforcement of the most heavily loaded areas.On the bottom, the stiffening ribs are designed as radial ridges radiating from the central zone to the periphery. The radial ridges do not touch each other in the center, forming a smooth central insert with a diameter of, for example, 50-300 mm. The number of radial ridges is determined by the bottom diameter and can range from 3 to 24. Additional load-bearing capacity is provided by flanges formed at the top of the sidewall of the foundation, at the ends of the wall rings, and at the bottom of the transition cone in the form of annular thickenings. The flanges support axial loads from the screed, soil pressure, and overlying elements, working in conjunction with the mesh structure of the ridges as single force belts, increasing the overall annular and spatial rigidity of the well. This design allows for uniform distribution of stresses from loads, eliminates stress concentrators in the center of the bottom, and increases the rigidity and anchoring properties of the bottom by filling the cavities between the ridges with soil.

[0014] The inner surface of the sidewall and bottom is smooth and free of any protruding structural elements, such as vertical projections, flanges, or internal ribs. The ridges on the sidewall are extruded outward, creating recesses on the inner surface that are oriented along the longitudinal axis and create no obstructions. The radial ridges on the bottom are extruded inward, toward the interior, eliminating the formation of cavities accessible to soil and maintaining the smoothness of the outer supporting surface. This design of the inner surface eliminates localized zones that could impede the flow of working fluids, installation, or operation of equipment. It ensures ease of cleaning, inspection, and maintenance, regardless of the well's intended use. It also eliminates stress concentrators and facilitates removal of the product from the mold.

[0015] The proposed foundation of the prefabricated sewer well is disclosed in detail on the basis of a drawing representing a general view of the foundation of the prefabricated sewer well in axonometry, where:

[0016] 1 - base,

[0017] 2 - side wall of the base,

[0018] 3 - bottom,

[0019] 4 - edge,

[0020] 5 - radial zigs,

[0021] 6 - central smooth zone of the bottom,

[0022] 7 - flange,

[0023] 8 - sealing groove,

[0024] 9 - holes for tie bolts,

[0025] 10 - ring ridges,

[0026] 11 - longitudinal zigs,

[0027] 12 - closed cells.

[0028] In a particular embodiment, the base 1 of the prefabricated sewer manhole includes a side wall 2 of a cylindrical shape with a height of 1000 mm and a diameter of 1000 mm, made by rotational molding from polypropylene with a wall thickness of 10 mm, and a bottom 3 made flat with an edge 4 protruding beyond the outer surface of the side wall 2. The width of the edge 4 is 40 mm. On the surface of the bottom 3, 6 radial ridges 5 are made, protruding to a height of 50 mm and having a width of 70 mm, diverging from the central smooth zone of the bottom 6 with a diameter of 250 mm to the periphery with an angular step of 60°, while the radial ridges 5 do not intersect with each other. Flange 7 of the side wall 2 is provided with a sealing groove 8 of a trapezoidal cross-section and holes 9 for tie bolts.On the outer surface of the side wall 2, 4 annular ridges 10 are formed, protruding to a height of 50 mm and having a width of 70 mm, arranged with an uneven pitch along the entire height from the bottom 3 to the flange 7. Also on the outer surface of the side wall 2, 6 longitudinal ridges 11 are formed, having similar dimensions, a height of 50 mm, a width of 70 mm, and evenly distributed along the circumference. The annular ridges 10 and the longitudinal ridges 11 intersect, forming closed cells 12. The inner surface of the side wall 2 is made without protruding elements, with depressed recesses corresponding to the outer ridges, and on the bottom 3, the radial ridges are extruded inward, away from the ground.

[0029] The prefabricated sewer manhole base is used as follows. During installation of the manhole on-site, base 1 is placed in a prepared pit so that the flat bottom 3 with edge 4 rests entirely on the ground. The developed mesh structure of annular 10 and longitudinal 11 ridges on the side wall of base 2 increases the contact area with the backfill soil. Closed cells 12 are filled with soil, creating mechanical interlocking that prevents the manhole from floating in waterlogged soils. Radial ridges 5 on bottom 3 also increase friction with the soil and enhance shear resistance. If necessary, partial concreting can be performed under bottom 3; however, due to its high anchoring capacity, the volume of concrete can be significantly reduced or even eliminated. Then, a shaft ring is installed on flange 7 of side wall 2, having first placed a rubber seal in groove 8.A centering element (a flange or groove) ensures automatic alignment of the ring and foundation without additional marking. Flange 7 is tightened to the shaft ring flange using bolts inserted through holes 9, tightening them uniformly. Next, the well shaft is raised to the design height, and the transition cone and manhole are installed. During operation, the mesh ribbing of the outer surface maintains the geometry of the foundation sidewall under soil pressure and seasonal movements.

[0030] Thus, when using the foundation of a prefabricated sewer manhole, the stated technical result is achieved: an increase in the annular and spatial rigidity of the structure, an increase in the friction force and anchoring capacity relative to the ground, a decrease in material consumption and a simplification of the manufacturing technology, a reduction in the volume of concrete work during installation, as well as an increase in the accuracy and speed of installation, ensuring the coaxial installation of shaft rings without additional operations.

Claims

1. A base for a prefabricated sewer manhole, comprising a side wall with a flange and a bottom, characterized in that on the outer surface of the side wall there are stiffening ribs in the form of annular ridges intersecting with longitudinal ridges and jointly forming a regular mesh structure covering the side wall, and the bottom is made flat, with an edge protruding beyond the outer surface of the side wall, and contains radial stiffening ribs made in the form of radial ridges.

2. The base according to paragraph 1, characterized in that the flange of the side wall is provided with a centering element made in the form of an annular collar or groove, ensuring coaxial fixation of the installed shaft ring.

3. The base according to paragraph 1, characterized in that the mesh structure of the outer ribbing extends over the entire height of the side wall from the bottom to the flange.

4. The base according to paragraph 1, characterized in that the flange additionally contains a sealing groove for accommodating a rubber seal and openings for tie bolts.

5. The base according to paragraph 1, characterized in that the bottom and side wall with zigs are made by rotational molding from polypropylene, polyethylene or unplasticized polyvinyl chloride.

6. The base according to paragraph 1, characterized in that it is made cylindrical or conical in shape with an expansion towards the top.

7. The base according to paragraph 1, characterized in that the mesh structure of the zigs has a rectangular or square shape.

8. A base according to any one of paragraphs 1-7, characterized in that the radial ridges on the bottom are designed with the possibility of diverging from the central zone to the periphery without intersecting with each other, with the formation of a smooth central insert.

9. A base according to any one of paragraphs 1-8, characterized in that the width of the edge is from 10 to 100 mm, and the thickness of the edge is equal to the thickness of the bottom or is increased due to local thickening.

10. A base according to any one of paragraphs 1-9, characterized in that the annular and longitudinal ridges have a depth of 10 to 100 mm and a width of 10 to 100 mm, and the pitch between the annular ridges is from 50 to 500 mm.

11. A base according to any of paragraphs 1-10, characterized in that the number of radial zigs on the bottom is from 3 to 24.

12. A base according to any of paragraphs 1-11, characterized in that the inner surface of the side wall and bottom is smooth-walled, without vertical projections, flanges, and internal ribs.

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