Alignment Control of Drilling Rods by Integrated Microchips-Paper

Paper

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The paper presents a microchip-based system for controlling the alignment of jet-grouting rods, developed to improve the accuracy and watertightness of deep excavation seals. In Berlin, high groundwater levels and strict limits on construction dewatering make artificial sealing layers essential. Jet-grouted slabs are widely used because they can provide both a water barrier and structural support.<br /><br />The system turns a standard drilling rod into a chain inclinometer. Sensors with two-directional inclinometer functions are built into special couplings that connect the rods and conduct electric current and data along the assembled rod. Measurements are displayed in the drilling rig operator’s cabin, allowing deviations to be identified and corrected during drilling rather than after construction. Magnetic reference points record how rods are assembled, while a compass mounted above ground establishes north orientation and avoids interference from buried metal. Data can also be sent to an off-site server for project-wide visualization and assessment of column overlap.<br /><br />Knowing the rod’s position at depth also supports trials to determine the geometry of cured jet-grouted columns. Vibration measurements taken as a jet beam contacts a cured column can be used to estimate its diameter. In addition, an asymmetric drilling bit can use deviation forces to steer the rod and correct its path; position data can also help control nozzle location when forming partial columns.<br /><br />The technology has been used in Berlin since summer 2019. The paper reports 12 completed projects involving horizontal jet-grouted slabs at depths of 8–20 metres, all watertight under applicable building-permit requirements. The authors conclude that continuous alignment monitoring, depth-specific geometry assessment and directional control raise the quality and reliability of jet grouting.

Keywords

jet grouting

microchip-based system

rod alignment

inclination monitoring

deep excavation

watertightness

groundwater control

drilling rod

Berlin construction

column overlap