Vacuum-Assisted Grout Injection for Structural Reinforcement
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Solution Overview
Problem
The existing method of reinforcing structures by injecting cementitious grout into a fabric sock within a drilled hole often results in incomplete grout seepage due to pressure restrictions, leading to an ineffective bond and potential structural damage from increased pressure, along with the formation of bubbles and air pockets that weaken the reinforced structure.
Innovation Solution
A method involving an elongate reinforcement core with an expandable sock, where a vacuum tube extends into the distal quarter of the hole to reduce pressure and enhance grout seepage, while a grout tube pumps cementitious grout under pressure, ensuring complete filling and minimizing internal pressure and air pockets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If injection pressure is increased to improve grout seepage through the fabric sock, then grout filling is improved, but structure damage risk increases and internal stresses are caused
Solution Approach 1:
Instead of using high pressure to force grout through the sock, the patent applies vacuum pressure to pull grout through the sock. The vacuum source creates negative pressure that draws grout from the injection point through the fabric sock and into the drilling, achieving complete filling without subjecting the structure to damaging high pressures.
Solution Approach 2:
The fabric sock acts as an intermediary that facilitates controlled grout transfer. It allows grout to pass through its porous structure while maintaining a seal against the drilling wall, enabling complete filling without requiring excessive pressure that would damage the structure.
2Manufacturing precision
If injection pressure is increased to improve grout seepage through the fabric sock, then grout filling is improved, but internal stresses in the structure increase
Solution Approach 1:
The patent inverts the pressure approach by using vacuum (negative pressure) instead of high positive pressure. The vacuum source creates a pressure gradient that pulls grout through the sock and into the drilling, achieving complete filling while avoiding the internal stresses and structural distortion caused by high injection pressure.
3Manufacturing precision
If vacuum pressure is applied to improve grout seepage, then grout filling is improved, but air pockets may form
Solution Approach 1:
The vacuum is applied in advance and continuously during the grout injection process. This preliminary and continuous vacuum application ensures that air is evacuated from the drilling before and during grout filling, preventing air pocket formation and ensuring complete grout saturation of the drilling.
Solution Approach 2:
The vacuum is maintained continuously throughout the grout injection process, ensuring uninterrupted air evacuation. This continuous action prevents air pockets from forming as grout fills the drilling, maintaining complete saturation without voids.
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 method improves the bond strength between the reinforcement core and the structure by ensuring complete grout filling, reducing internal pressure, and eliminating air pockets, resulting in a stronger and more effectively reinforced structure.
Implementation Method 1
reducing the pressure in the hole by means of a vacuum tube
Implementation Method 2
the sock being formed from a material which is permeable to the liquid so as to allow the liquid to seep through the sock
Implementation Method 3
The grout expands the sock under pressure to fill the space around the rod
Data Source
Figure 1a
Figure 2~3
Figure 4
AI summary
Disclosed is a method of reinforcing a structure (10) having an elongate hole (14) or drilling the hole having an open proximal end (11) and a closed distal end (16). The method comprises the steps of inserting into the open end of the hole an elongate reinforcement core (20) carrying over at least part of its length an expandable sock (30), introducing a settable liquid (40), such as grout, into the sock at a first pressure so as to cause expansion of the sock toward the wall (18) of the hole (14), the sock being formed from a material which is permeable to the grout so as to allow the liquid to seep through the sock, reducing the pressure in the hole by means of a vacuum tube (23), whilst said introducing step is taking place, to at least a second pressure lower than the first pressure so as to encourage the grout to seep through the sock, to substantially fill the hole. The method also includes the step of ensuring that the vacuum tube extends substantially into the distal quarter of the length of the closed hole. Thus in embodiments of the invention, in producing a vacuum within the hole/drilling the seepage of the liquid or grout through the sock to make contact and bond with the wall of the drilling is increased along the whole length of the drilling.