Sonic Drilling for Geothermal Micropile Installation and Grouting
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Solution Overview
Problem
Conventional drill rigs face difficulties in quickly and efficiently drilling cased holes in challenging lithologies, and there is a need for improved control and monitoring of the grouting process in geothermal heat exchange and underground thermal energy storage systems.
Innovation Solution
A sonic drilling method using a rotating and vibrating drill string with a removable drill bit, allowing for quick drilling of cased holes and accurate grouting process monitoring, where the drill bit is decoupled after reaching the desired depth, and concrete or grouting material is introduced into the hole.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional drill rigs are used to drill cased holes, then drilling can be performed with standard equipment, but drilling speed is slow and efficiency is reduced in challenging lithologies
Solution Approach 1:
The patent employs a sonic drilling system that uses high-frequency vibration (typically 20-100 Hz) applied to the drill string to dramatically increase drilling speed through challenging lithologies. The vibration creates resonant frequencies that break up rock and soil more efficiently than conventional rotary drilling alone, enabling faster penetration rates while maintaining control through the cased hole system.
Solution Approach 2:
The drilling system is divided into separable components: a removable drill bit that can be detached from the drill string after drilling is complete. This segmentation allows the drill bit to be retrieved separately while leaving the cased hole intact, improving efficiency by eliminating the need to retrieve the entire drill string and enabling faster subsequent grouting operations.
2Measurement precision
If conventional drilling methods are used, then equipment is simpler, but control and monitoring of the grouting process is less accurate
Solution Approach 1:
The sonic drilling system incorporates sensors and monitoring equipment that provide real-time feedback on drilling parameters, hole depth, and grouting material placement. This feedback mechanism allows for precise control of the grouting process, ensuring accurate placement and dosage of grout materials while maintaining records of the installation process for quality assurance.
3Measurement precision
If the drill bit remains attached to the drill string during grouting, then the drilling system is simpler, but the grouting process cannot be properly monitored and controlled
Solution Approach 1:
The drill bit is designed to be removable from the drill string after drilling is complete. This extraction allows the drill bit to be taken out while the cased hole remains in place, enabling proper monitoring and control of the subsequent grouting process without the drill bit interfering with grout placement or sensor operation.
4Loss of time
If conventional drilling speed is used, then equipment complexity is lower, but installation time for geothermal transfer apparatuses is excessive
Solution Approach 1:
The sonic drilling system uses high-frequency vibration to dramatically reduce drilling time through challenging lithologies. The vibratory action breaks up soil and rock more efficiently than conventional rotary drilling, enabling faster installation of cased holes for geothermal transfer apparatuses while the removable drill bit design further reduces total installation time by eliminating drill string retrieval operations.
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 rapid installation of geothermal transfer apparatuses and underground support structures, such as cast-in-place concrete piles and micropiles, with enhanced accuracy and efficiency, even in difficult geological conditions.
Implementation Method 1
A sonic drilling apparatus includes a rotating and vibrating apparatus for rotating and vibrating a drill string into the ground
Implementation Method 2
rotating and vibrating a drill string into the ground to form a cased hole
Data Source
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AI summary
There is provided a method for drilling a cased hole and installing a micropile. A sonic drilling apparatus is positioned at a desired location. The sonic drilling apparatus includes a rotating and vibrating apparatus for rotating and vibrating a drill string into the ground. A retrievable drill bit is operatively connected to the drill string. The cased hole is drilled to a desired depth by rotating and vibrating the drill string into the ground. The retrievable drill bit is retrieved from the cased hole following the drilling of the cased hole to the desired depth. A micropile is lowered into the cased hole following the retrieval of the retrievable drill bit. Grouting material may be discharged into the cased hole before or after the drill string is removed from the ground. In another embodiment, a removable drill bit may be used in place of the retrievable drill bit.