Ramming Pile Base Enlargement via Reduced Outlet Drive Pipe
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Solution Overview
Problem
Existing methods for producing in-situ concrete displacement piles do not effectively enhance the load-bearing capacity of such piles, limiting their structural integrity and efficiency.
Innovation Solution
A method involving a jacking pipe with an outlet opening of reduced diameter compared to the inner tube diameter, where fresh concrete is discharged into the subsoil, and the pipe is driven into the concrete to widen the pile base through top ramming, increasing the pile's load-bearing capacity by compacting the surrounding soil.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional head ramming or external driving is used to install cast-in-place concrete piles, then the installation process is simple and straightforward, but the load-bearing capacity of the piles is limited and cannot be significantly enhanced
Solution Approach 1:
The installation process is divided into distinct phases: initial driving to target depth, withdrawal to create space, and repeated insertion into fresh concrete to form the enlarged base. This segmentation allows each phase to be optimized independently, achieving high load-bearing capacity through controlled concrete displacement while maintaining manageable procedural complexity
Solution Approach 2:
Fresh concrete is placed in the borehole before the enlargement operation begins. This preliminary action ensures that the concrete is already in position to be displaced and compacted, rather than requiring subsequent placement operations. The concrete serves as both the filling material and the medium for base enlargement, streamlining the overall process
2Strength
If the drive pipe is driven deeper to increase pile length, then the pile can reach stronger soil layers, but the load-bearing capacity is still limited by the small base area
Solution Approach 1:
Instead of increasing load-bearing capacity solely through vertical extension (length), the invention transitions to horizontal enlargement of the pile base (area). By creating an enlarged base through displacement of fresh concrete, the bearing area is increased in the horizontal dimension, providing additional load-bearing capacity without requiring excessive pile length
Solution Approach 2:
The invention changes the critical parameter from pile length to base area. By focusing on enlarging the base diameter through controlled concrete displacement, the load-bearing capacity increases through area expansion rather than length extension. This parameter shift allows optimization of pile design based on site-specific conditions
3Strength
If internal ramming is used to compact fresh concrete in the borehole, then the concrete can be densely packed, but the load-bearing capacity is not significantly improved compared to conventional methods
Solution Approach 1:
The fresh concrete itself serves as the compaction medium. As the drive pipe is inserted into the concrete, the concrete is displaced and compacted by its own movement and the friction against the pipe walls. This self-compaction mechanism eliminates the need for separate internal ramming operations while achieving dense concrete placement and base enlargement simultaneously
Solution Approach 2:
The compaction process is dynamic rather than static. The drive pipe is repeatedly inserted and withdrawn, creating dynamic displacement and compaction of the concrete. This dynamic action ensures thorough compaction and base enlargement, transforming the concrete from a passive filling material to an active compaction medium
4Strength
If a standard outlet opening is used in the drive pipe, then concrete flows out freely, but the drive pipe cannot effectively widen the pile base
Solution Approach 1:
The outlet opening has a specifically designed reduced diameter compared to the drive pipe's inner diameter. This local quality change at the outlet creates controlled flow conditions, allowing the concrete to be displaced laterally as the pipe is inserted. The reduced outlet diameter is the key local feature that enables base enlargement while maintaining overall drive pipe simplicity
Solution Approach 2:
The outlet opening is designed with a curved or rounded geometry rather than a sharp edge. This curvature helps guide the concrete flow smoothly from the reduced diameter outlet, preventing clogging and ensuring consistent displacement. The rounded outlet geometry facilitates the lateral spreading of concrete needed for base enlargement
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 significantly improves the load-bearing capacity of in-situ concrete displacement piles, allowing them to be designed as shorter or smaller diameter piles with enhanced structural integrity compared to conventional simplex piles, nearly doubling their load-bearing capacity.
Implementation Method 1
creating a borehole by driving the drive pipe into the subsoil by means of head ramming
Implementation Method 2
lifting the drive pipe by a defined length, whereby fresh concrete flows out of the outlet opening into the borehole
Implementation Method 3
insertion of the drive pipe into the fresh concrete that has already flowed into the borehole to form a widened pile base
Data Source
Figure 1~2
Figure 3a~3e
Figure 4
AI summary
The invention relates to a method for producing a cast-in-place concrete displacement pile in a subsoil (11), comprising the following steps: providing a closed-end drive pipe (1; 21) with an end outlet (4; 24) for dispensing fresh concrete (15) into the subsoil (11), wherein the outlet (4; 24) has an outlet opening (6) with an outlet opening diameter (D3) reduced compared to the inner pipe diameter (D2) of the drive pipe (1); creating a borehole (12) by driving the drive pipe (1; 21) into the subsoil (11) by head driving until a defined borehole depth (13) is reached, wherein the outlet opening (6) is closed; filling the drive pipe (1; 21) with fresh concrete (15); opening the outlet opening (6); and raising the drive pipe (1; 21) by a defined length. (A), wherein fresh concrete (15) flows out of the outlet opening (6) into the borehole (12), and insertion of the drive pipe (1;21) into the fresh concrete (15) already flowed into the borehole (12) to form a widened pile base (16) of the cast-in-place displacement pile. The invention further relates to a device for carrying out the method for producing a cast-in-place displacement pile in the subsoil (11).