Helical Blade Plugging Device for Micropile Grout Sealing
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Solution Overview
Problem
The production of micropile foundations is slowed down by the need for a waiting period between pouring the first grout and injecting the second grout under pressure, as the first grout must set to form a sheath and prevent grout from splashing out, which also risks insufficient grip or leakage if not timed correctly.
Innovation Solution
A closure device with a tubular wall, helical blades, and a cap is used to seal the borehole, allowing for immediate pressure injection of cement grout without waiting for the first grout to set, by anchoring itself in the ground and preventing grout from rising through the surrounding soil.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the first grout is allowed to set for several hours to seal the borehole, then the grout can prevent subsequent grout from splashing back to the surface, but the installation of micropiles becomes slower and more laborious
Solution Approach 1:
A mechanical obturator device is introduced as an intermediary element between the first and second grout stages. This device provides immediate mechanical sealing of the borehole, replacing the need to wait for chemical setting of the first grout. The obturator can be removed after second grout injection, having served its purpose as a temporary seal.
Solution Approach 2:
The obturator device is installed in advance before the second grout injection, creating the seal proactively rather than passively waiting for the first grout to set. This preliminary mechanical sealing action enables immediate progression to the next construction stage.
2Reliability
If the waiting period is too long, then the borehole is properly sealed, but excessive setting of the liner prevents subsequent grout from passing radially through it
Solution Approach 1:
The obturator acts as a controlled intermediary that provides sealing without the unwanted side effect of excessive setting. Since it is a removable mechanical device rather than a setting material, it seals the borehole effectively while allowing precise control over when and how the second grout penetrates radially.
Solution Approach 2:
The obturator is a temporary element that is discarded (removed) after serving its sealing purpose. This removal restores full radial penetration capability for the second grout without the constraints of a set liner.
3Productivity
If the waiting period is too short, then the installation process is faster, but insufficient setting of the liner allows grout to leak to the surface
Solution Approach 1:
The obturator provides immediate mechanical containment of the second grout, eliminating the risk of surface leakage that would occur with insufficient first grout setting. This mechanical barrier is reliable from the moment of installation, enabling immediate grout injection without waiting.
Solution Approach 2:
The mechanical seal is established in advance through obturator installation, providing immediate grout containment capability. This preliminary action eliminates the need to wait for chemical setting while ensuring reliable grout containment from the start of the second grout stage.
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 simplifies and accelerates the construction of foundation elements by eliminating the waiting time, ensuring effective sealing and preventing grout leakage, thus allowing for faster and more controlled micropile production.
Implementation Method 1
the helical blade being radially projecting from an external face of the tubular wall... the plugging device is placed on an upper end of the borehole and rotated in a first direction around the central axis in such a way that the helical blade cuts into the ground around the borehole, thus driving the plugging device into the ground
Implementation Method 2
the cap closing the upper end of the tubular wall, said cap having at least one fluid supply connection for the injection of pressurized grout under the cap... during the injection of grout under pressure, helps prevent grout from rising through the surrounding soil
Data Source
Figure 1
Figure 2~3B
Figure 4
AI summary
The invention relates to a drilling plugging device (1,1',1") comprising at least one tubular wall (2), a helical blade (6a), and a cap (3). The tubular wall (2) is axisymmetric about a central axis (Z) and extends, along said central axis (Z), from an upper end (2a) closed by the cap (3) to an open lower end (2b). The helical blade (6a) projects radially from an outer face of the tubular wall (2), and the cap (3) includes at least one fluid supply connection (4) for injecting pressurized grout under the cap (3) and a mechanical coupling member (5) adapted to drive the plugging device (1,1',1") in rotation about said central axis (Z).