Absolute displacement monitoring system anchored in stable bedrock to measure movement of the structure's foundation.
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Absolute displacement monitoring system anchored in stable bedrock to measure movement of the structure's foundation.
The Geolook Inverted Plumbline System is designed to measure absolute horizontal movements of a structure's base relative to deep, stable bedrock. While a 'Normal' plumbline measures how much a dam leans relative to its base, an 'Inverted' plumbline tells you if the base itself is sliding or settling. The system consists of a groutable anchor installed deep in a borehole beneath the structure. A stainless steel wire connects this anchor to a float unit located in a tank at the top (usually in the dam gallery). The float keeps the wire perfectly vertical and tensioned, creating a fixed reference line that allows engineers to measure the movement of the surrounding structure against the stable earth.
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This is the most critical distinction in dam safety. A Normal Plumbline hangs from the top of the dam; if the whole dam slides downstream 50mm, the Normal Plumbline moves with it and might register 'Zero' deflection.
An Inverted Plumbline is rooted in the earth below the dam. If the dam slides, the wire stays still, and the instrument attached to the dam registers exactly 50mm of movement. This makes it the 'source of truth' for structural stability.
Installing an Inverted Plumbline is a precision operation. A vertical borehole (often 20-50 meters deep) must be drilled from the lowest gallery into competent bedrock.
The groutable anchor is lowered to the bottom and cemented in place. Once cured, it provides a rock-solid attachment point that effectively extends the 'stable earth' right up into the monitoring room.
Unlike a hanging weight, the Inverted system uses buoyancy. A float tank is installed at the top of the system (inspection gallery). The wire is attached to a float submerged in oil.
This float pulls the wire upward, keeping it taut and vertical. The oil serves a dual purpose: it provides the buoyancy force and also dampens any vibrations in the wire caused by water flow or machinery.
For standard applications, high-tensile Stainless Steel wire is sufficient. However, for extremely deep installations or areas with significant temperature gradients, Invar wire (a nickel-iron alloy) is recommended.
Invar has a near-zero coefficient of thermal expansion, ensuring the wire length does not fluctuate with seasonal temperature changes, maintaining constant buoyancy and tension.
This is the most critical distinction in dam safety. A Normal Plumbline hangs from the top of the dam; if the whole dam slides downstream 50mm, the Normal Plumbline moves with it and might register 'Zero' deflection.
An Inverted Plumbline is rooted in the earth below the dam. If the dam slides, the wire stays still, and the instrument attached to the dam registers exactly 50mm of movement. This makes it the 'source of truth' for structural stability.
Unlike a hanging weight, the Inverted system uses buoyancy. A float tank is installed at the top of the system (inspection gallery). The wire is attached to a float submerged in oil.
This float pulls the wire upward, keeping it taut and vertical. The oil serves a dual purpose: it provides the buoyancy force and also dampens any vibrations in the wire caused by water flow or machinery.
Installing an Inverted Plumbline is a precision operation. A vertical borehole (often 20-50 meters deep) must be drilled from the lowest gallery into competent bedrock.
The groutable anchor is lowered to the bottom and cemented in place. Once cured, it provides a rock-solid attachment point that effectively extends the 'stable earth' right up into the monitoring room.
For standard applications, high-tensile Stainless Steel wire is sufficient. However, for extremely deep installations or areas with significant temperature gradients, Invar wire (a nickel-iron alloy) is recommended.
Invar has a near-zero coefficient of thermal expansion, ensuring the wire length does not fluctuate with seasonal temperature changes, maintaining constant buoyancy and tension.
We are currently updating the specific model configurations and technical datasheets for this product category.