Wave-Shaped Grouting Bulb for Micropile Bearing Capacity
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Solution Overview
Problem
Conventional micropile construction methods struggle to achieve high bearing capacity in soil layers without rock, leading to instability and prolonged construction times due to uneven grouting material distribution and limited skin friction force.
Innovation Solution
A wave-shaped grouting bulb with uniform protrusions and a predetermined formation distance is formed using jet-grouting, allowing for enhanced structural stability and increased bearing capacity by integrating a steel bar within the grouting bulb.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional grouting method is used, then construction process is simple, but bearing capacity is insufficient in soil layers without rock
Solution Approach 1:
The grouting bulb is segmented into multiple protrusions instead of a single continuous structure. Each protrusion acts as an independent load-bearing element, increasing the overall bearing capacity by distributing stresses across multiple points while maintaining a relatively simple construction process.
Solution Approach 2:
The grouting bulb transitions from a two-dimensional circular cross-section to a three-dimensional wave-shaped structure with protrusions. This dimensional change increases the surface area and volume of the grouting bulb, enhancing skin friction and bearing capacity without significantly increasing the drilled hole diameter.
2Reliability
If grouting is repeated 3-6 times to compensate contraction, then grouting quality improves, but construction time increases
Solution Approach 1:
The wave-shaped grouting bulb is formed in advance before steel bar installation. The protrusions are pre-formed through jet-grouting, creating a ready-to-receive-steel-structure that eliminates the need for repeated grouting operations and allows for faster construction while maintaining quality.
Solution Approach 2:
The jet-grouting process continuously forms the wave-shaped grouting bulb in a single operation, eliminating the interrupted repeated grouting process. This continuous action maintains consistent grouting quality while significantly reducing construction time.
3Strength
If steel bar diameter is small relative to length, then micropile flexibility improves, but end bearing capacity is limited
Solution Approach 1:
The steel bar is segmented into multiple protrusions that extend beyond the cylindrical pillar part. These protrusions act as additional bearing elements at the end of the micropile, increasing end bearing capacity without requiring a significantly larger steel bar diameter.
Solution Approach 2:
The protrusions are nested within the grouting bulb structure, with the steel bar protrusions extending from the cylindrical pillar part and being surrounded by the grouting material. This nesting arrangement integrates the steel bar geometry with the grouting bulb to maximize bearing capacity.
4Manufacturing precision
If grouting material is injected until flowing out of entrance, then grouting fills drilled hole completely, but injection pressure cannot be uniformly maintained
Solution Approach 1:
The wave-shaped grouting bulb is formed in advance through jet-grouting before steel bar installation. This preliminary formation creates a structured grouting mass with controlled geometry, ensuring complete filling of the drilled hole while maintaining uniform injection pressure throughout the process.
Solution Approach 2:
The grouting material distribution transitions from a uniform radial pattern to a three-dimensional wave-shaped structure with protrusions. This dimensional change allows the grouting material to fill the drilled hole completely while maintaining uniform pressure distribution across the grouting mass.
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 wave-shaped grouting bulb improves skin friction and resistance to compression and pullout, enabling higher bearing capacity and structural stability in micropiles, even in soil layers without rock, while reducing construction time and costs.
Implementation Method 1
spraying, at high pressure, the grout material from the grout material spray hole (220) into the drilled hole (2)
Data Source
AI summary
The present invention provides a wave-shaped grouting bulb (100) for securing an underground bearing capacity of a steel bar (10), the bulb comprising a plurality of protrusions (120), which have a predetermined maximum diameter (D1) and are formed along the longitudinal direction of a cylindrical pillar part (110) extending downward, wherein the neighboring protrusions (120) are formed to be spaced from each other by a predetermined formation distance (s). The present invention has an advantageous effect of improving a skin friction force and resistance to compression and pullout in the grouting bulb integrated with the steel bar and thus enhancing structural stability in the micropile body.