Inflatable-Bag Steering Head for Remote Pipe Ramming Direction Control
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Solution Overview
Problem
Trenchless construction methods, particularly pipe ramming, lack a reliable steering mechanism for horizontal casing installation, leading to unpredictable deviations in line and grade, necessitating frequent disconnection and manual correction, which is costly and unsafe.
Innovation Solution
A steering head with inflatable bags and a shell member that allows for remote control of direction changes by inflating or deflating specific bags, using mechanical structures to react with the earth and adjust the casing's path.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional pipe ramming without steering mechanism is used, then the construction method is simple and cost-effective, but the bore direction cannot be controlled leading to unpredictable deviations
Solution Approach 1:
The steering head is divided into multiple independent inflatable bags arranged circumferentially, each capable of being inflated independently to steer the bore in different directions. This segmentation allows precise directional control without requiring a complex integrated steering system.
Solution Approach 2:
The steering mechanism utilizes changes in the physical state of the inflatable bags (from deflated to inflated) to alter the bore direction. By changing the volume and pressure parameters of the bags, the casing can be steered dynamically during the ramming operation.
2Reliability
If frequent disconnection and manual correction is performed to correct bore deviations, then steering accuracy can be improved, but productivity decreases and safety risks increase
Solution Approach 1:
The steering head is installed at the beginning of the pipe ramming operation, allowing directional corrections to be made proactively during the boring process rather than requiring disconnection and manual correction after deviations occur. This preliminary positioning of the steering mechanism enables continuous guidance.
Solution Approach 2:
The inflatable bag steering system allows the casing to self-correct its own direction during installation by inflating specific bags to push against the soil, eliminating the need for external intervention or disconnection to correct deviations.
3Reliability
If hydraulic jacks with steering flaps are used for steering, then direction control is achieved, but the device complexity and space requirements increase significantly
Solution Approach 1:
The invention uses inflatable bags (pneumatic elements) instead of hydraulic jacks to achieve steering. The pneumatic bags are simpler in structure, require less space, and can be inflated through flexible hoses without requiring the complex mechanical linkages and large annular spaces needed for hydraulic steering systems.
Solution Approach 2:
The inflatable bags are made of flexible material that can expand and contract as needed for steering. This flexible shell approach replaces rigid hydraulic components with adaptable pneumatic elements that conform to the available space within the casing wall thickness.
4Reliability
If larger casing diameter is installed to prevent bore deviation, then bore stability is improved, but the cost and difficulty of installation increase
Solution Approach 1:
Instead of using a statically larger casing to prevent deviation, the invention introduces a dynamic steering system that actively adjusts the bore direction during installation. This allows the use of appropriately sized casing while maintaining stability through real-time directional control.
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
Enables precise control over the direction of the casing during pipe ramming operations, reducing the need for frequent disconnection and manual correction, enhancing safety and efficiency.
Implementation Method 1
Upon an inflation of the inflatable bag, at least a portion of the shell member axially adjacent to an underlying inflatable bag extends radially outward
Implementation Method 2
Upon application of a high flow rate of high-pressure air to the pneumatic hammer, a steel slug moves back and forth, causing the hammer to strike the rear of the casing
Data Source
AI summary
A steering head for a pipe ramming hammer bore construction system, configured to allows passage of soil through the center of the steering head while maintaining the ability to change the bore alignment through the use of inflatable bags which are underlying and adjacent to a portion of a shell member which extends radially outward from the steering head upon inflation of the inflatable bag. The inflatable bags may be inflated by inflation media supply lines which extend from the bore pit to the steering head and deflated by release of the inflation media. The media flow to the inflatable bags may be controlled by media valves which may be located in the steering head or, alternatively, at a different location, such as in the bore pit. The remote nature of the system eliminates the need for frequent removal of the pneumatic hammer, confined space entry, and manual corrections performed inside the casing.