Flexible Sleeve for Manhole Height Adjustment
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Solution Overview
Problem
The existing methods for raising manhole castings require a stack of concrete or hard rubber spacer rings, which are cumbersome and inefficient, and do not provide a stable solution for achieving the correct height and alignment with the final pavement level.
Innovation Solution
A flexible sleeve is used, taller than the required distance, which compresses downward to fix the casting height and is stiff enough to maintain shape during backfilling, with a casting support ensuring the correct positioning and height adjustment, eliminating the need for spacer rings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a stack of concrete or hard rubber spacer rings is used to raise the manhole casting, then the casting can be positioned at the correct height, but the process becomes cumbersome and inefficient with multiple components requiring assembly and alignment
Solution Approach 1:
The patent merges multiple spacer rings into a single integrated sleeve structure. The sleeve combines the height-adjustment function of multiple rings with the structural support function, eliminating the need to assemble and align multiple separate components. This single sleeve component provides the same height-raising function while dramatically simplifying the installation process and reducing the number of parts involved.
Solution Approach 2:
The sleeve serves multiple functions simultaneously: it provides height adjustment, structural support during backfilling, and alignment guidance for the casting. By consolidating these functions into a single component, the invention eliminates the need for separate spacer rings, support structures, and alignment devices, thereby improving ease of operation while reducing device complexity.
2Reliability
If spacer rings are used to support the casting, then height adjustment is possible, but stability during backfilling is compromised as rings may shift or collapse
Solution Approach 1:
The patent employs a flexible sleeve structure that can compress vertically under the weight of the casting while maintaining lateral stiffness to resist collapse during backfilling. This flexible shell design allows the sleeve to adapt to the loading conditions - compressing to accommodate the casting weight while maintaining structural integrity against lateral earth pressures, thereby ensuring stability without requiring multiple rigid components.
Solution Approach 2:
The sleeve is constructed from composite materials or a composite structure that combines vertical flexibility with lateral rigidity. This allows the single component to exhibit different mechanical properties in different directions - flexible vertically to accommodate compression under the casting, but stiff laterally to prevent collapse during backfilling, thus improving reliability and productivity simultaneously.
3Manufacturing precision
If multiple spacer rings are stacked to achieve the required height, then the casting can be raised to the correct level, but precise height adjustment and alignment with the final pavement level become difficult
Solution Approach 1:
The patent enables continuous height adjustment by allowing the sleeve to compress to varying degrees under different loading conditions. Instead of being limited to discrete height increments determined by the number of rings stacked, the flexible sleeve can compress by any amount within its elastic range, providing precise and continuous height adjustment capability. This parameter change from discrete to continuous adjustment simplifies the mechanism while improving manufacturing precision.
4Stability of the object's composition
If a rigid structure is used to maintain shape during backfilling, then stability is improved, but the structure cannot compress to accommodate the casting weight and achieve proper height
Solution Approach 1:
The flexible sleeve structure maintains structural stability during backfilling through its lateral stiffness while simultaneously allowing vertical compression to accommodate the casting weight. The flexible shell design enables the structure to exhibit rigid behavior laterally (resisting collapse) while being compliant vertically (allowing compression), thus achieving both structural stability and ease of height adjustment with a single component.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution simplifies the process by allowing for precise height adjustment and stability during backfilling, ensuring the manhole cover is aligned with the final pavement level without collapsing, facilitating efficient pavement application.
Implementation Method 1
a sleeve which is taller than the required distance between the top of the manhole and the level at which the casting and manhole cover are to be finally located, but which is sufficiently flexible in a vertical direction that when a casting is located in the top of the sleeve, the sleeve compresses downwardly
Implementation Method 2
The sleeve is sufficiently stiff in a lateral direction that it does not collapse inwardly when the backfill is packed in and around the exterior of the sleeve
Data Source
AI summary
The specification discloses apparatus and a process in which the stack of concrete or hard rubber spacer rings used in raising manholes is eliminated. It is replaced with a sleeve which is taller than the required distance between the top of the manhole and the level at which the casting and manhole cover are to be finally located, but which is sufficiently flexible in a vertical direction that when a casting is located in the top of the sleeve, the sleeve compresses downwardly. The height of the casting is fixed by a casting support resting on the pavement base coat or other base surface to which the final pavement will be applied around the casting. The sleeve is sufficiently stiff in a lateral direction that it does not collapse inwardly when backfill is packed in and around the exterior of the sleeve. The casting support is removed and the final layer of pavement is applied over the base surface.