Zone Freeze Pipe Structure for Selective Ground Freezing
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Solution Overview
Problem
Conventional ground freezing methods require excessive energy and resources to freeze the entire soil region, making it inefficient for selective groundwater control and excavation support.
Innovation Solution
The zone freeze pipe design, featuring a plastic upper section with low heat transfer and a metal lower section with high heat transfer, allows for selective freezing of ground segments, reducing energy consumption and enabling easier excavation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional full freeze pipes are used to freeze soil from ground surface to bottom, then groundwater cutoff and shoring are effective, but excessive energy and refrigeration resources are consumed
Solution Approach 1:
The freeze pipe is divided into two distinct sections: an upper section with insulation and a standard pipe wall thickness, and a lower section with enhanced wall thickness. This segmentation allows different portions of the pipe to serve different functions - the upper section minimizes heat transfer and energy consumption, while the lower section provides sufficient freezing capability for groundwater cutoff, thus resolving the contradiction between effectiveness and energy consumption.
Solution Approach 2:
The pipe wall thickness is varied locally along the length of the freeze pipe. The lower section has a greater wall thickness (0.5-1 inch) compared to the upper section (standard thickness), creating local differences in heat transfer characteristics. This local quality adjustment enables the system to achieve effective groundwater cutoff at the critical lower zone without the excessive energy consumption that would result from thick-walled piping throughout the entire length.
2Reliability
If full length freeze pipes are used, then complete soil freezing is achieved, but excavation efficiency is reduced due to frozen soil above the frozen plug
Solution Approach 1:
The freeze pipe is segmented into an upper section with standard insulation and a lower section with enhanced freezing capability. This segmentation ensures that only the necessary lower portion of the soil is frozen for structural support, while the upper soil remains unfrozen and easily excavable, thus resolving the contradiction between soil stabilization and excavation efficiency.
Solution Approach 2:
The enhanced wall thickness in the lower section creates a localized freezing zone that provides sufficient soil stabilization for excavation support without extending freezing to unnecessary upper areas. This local quality differentiation maintains productivity by keeping excavation-friendly conditions in the upper zone while achieving stabilization where needed in the lower zone.
3Stability of the object's composition
If uniform heat transfer throughout the pipe is maintained, then even soil freezing is achieved, but energy consumption increases unnecessarily
Solution Approach 1:
The pipe design implements non-uniform heat transfer characteristics through varying wall thickness - the lower section has greater thickness for effective freezing, while the upper section has standard thickness to minimize heat transfer. This local quality variation eliminates the unnecessary energy consumption associated with uniform freezing throughout the entire pipe length, while still achieving stable soil composition in the critical lower zone.
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 approach significantly reduces the amount of refrigeration and electricity needed, allowing for effective groundwater cutoff and structural support while minimizing freezing above the frozen plug, thus enhancing excavation efficiency and reducing operational costs.
Implementation Method 1
a plastic upper casing defining an upper cavity
Implementation Method 2
a metal lower casing defining a lower cavity
Implementation Method 3
chilled brine to flow down from the top of the freeze pipe, along the outside annulus of the center pipe, and circulate evenly throughout its entire length
Implementation Method 4
Frozen soil begins to occur immediately around each freeze pipe when chilled brine is circulated through the system
Data Source
AI summary
An apparatus sometime referred to as a freeze pipe and methods of using these apparatus in ground freezing applications is provided. Ground freezing is a temporary ground support technique that is used extensively for groundwater control and ground stabilization in underground construction and deep excavations. The process involves circulating refrigerated liquids through a series of vertically disposed “freeze” pipes to freeze the ground creating a solid barrier that prevents water intrusion and provides structural support for excavation. The freeze pipes are directed to “zone freeze” pipes or the like, which cause the ground to freeze in selected segments along the pipe, also referred to as zones.