Single-Grain Rock Casting for Manhole Shaft Cover Stability
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Solution Overview
Problem
The existing methods for rehabilitating manholes in asphalt roads are time-consuming and prone to issues such as poor adhesion and cracking of the asphalt layer, leading to potential settlement and instability around the manhole cover supports.
Innovation Solution
A method using a casting compound composed of single-grain rock as the filling material, which forms a stable structural framework when packed, eliminating the need for a separate bituminous top layer and ensuring a strong bond with the surrounding road surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If traditional aggregate material is used for filling the opening, then the filling process is simple, but the spaces between grains collapse under heavy loads and the bond with surrounding street is poor
Solution Approach 1:
The patent changes the physical parameters of the filling material by using single-grain rock instead of traditional aggregate. This parameter change transforms the material structure from irregular grains with large voids to uniform spherical grains with minimal voids, creating a stable framework that maintains bond strength under load while simplifying the filling process.
Solution Approach 2:
The patent creates a composite filling material combining single-grain rock with grout. The single-grain rock provides a stable structural framework while the grout fills the minimal spaces between grains, creating a composite material that achieves both structural stability and good bond strength with the surrounding street.
2Productivity
If bituminous top layer is applied to complete backfilling, then the road surface can be formed, but the process becomes time-consuming and the asphalt layer is prone to cracking and detachment
Solution Approach 1:
The patent extracts and eliminates the need for a separate bituminous top layer by using single-grain rock filling material that directly forms the road surface. The uniform spherical grains create a stable structure that can serve as the surface layer itself, removing the problematic intermediate asphalt layer that was prone to cracking and detachment.
Solution Approach 2:
The patent changes the surface properties of the filling material by using single-grain rock with uniform spherical grains. This parameter change creates a stable, non-slip surface that eliminates the need for additional bituminous coating, thereby reducing rehabilitation time while improving the reliability of the road surface.
3Stability of the object's composition
If irregular aggregate material is used for filling, then the filling process is straightforward, but the spaces between grains are large and collapse under traffic loads
Solution Approach 1:
The patent applies parameter changes by transforming the filling material from irregular aggregate to single-grain rock with uniform spherical grains. This parameter transformation creates a stable framework structure that resists collapse under traffic loads while the grout easily fills the minimal spaces between grains, maintaining ease of manufacture.
Solution Approach 2:
The patent utilizes spheroidality by employing single-grain rock with spherical grains instead of irregular aggregate. The spherical shape of the grains allows for cubic dense packing with minimal voids, creating a stable framework that maintains structural integrity under load while the uniform geometry simplifies the filling process.
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
The method provides a quick, cost-effective, and durable solution that prevents settlement and wear, ensuring a stable and non-slip surface without the risk of asphalt detachment, suitable for both new construction and rehabilitation.
Implementation Method 1
By using such a mass (also referred to as aggregate), the entire space that arises when the opening is made between the existing road and the milled or chiseled shaft can be filled evenly - namely in the sense of a cubic dense packing of spheres.
Implementation Method 2
These spaces can then be filled with the grout. Since the free spaces are very small and also uniform, the free spaces do not collapse even under heavy loads
Data Source
Figure 1a
Figure 1b
Figure 2a
AI summary
The method involves forming an opening (30) around a shaft covering in a road (20), and closing the opening with a casting material (40), where the casting material is made from a filling material (41) i.e. grain rock, and a grouting mortar (42) e.g. non-shrink material or high-strength material, where grain size of the grain rock is 11 to 13 mm. The filling material and the grouting mortar are blended with one another before filling into the opening. The opening is formed in cylindrical or conical form in a vertical direction or formed in round or elliptical shape in a horizontal direction. An independent claim is also included for a casting material for casting a shaft covering.