Geotechnical Instrumentation for Monitoring.pptx

Geotechnical Instrumentation

1. Geotechnical Instrumentation

2. Introduction 2 Importance of Instrumentation : These instrumentation are for precise measurement of pore water pressure and detects signs of slope movement, which are crucial for monitoring tailing dams or embankments. This will also serve as an early warning system to detect potential failure or instabilities. Also provides valuable data for informed decision making and helps in deeper understanding of the structural integrity of the dam. Types of Instrumentation : Piezometers: used for measuring pore water pressure in a confined aquifer or at a special horizon of the geological profile within the embankment . Standpipe Piezometer Vib rating Wire Piezometer Inclinometers: used for measuring lateral or horizontal movements within the embankment. Portable Inclinometers 2 Short Example: Deduction of failure plane from inclinometers (other factors also mandatory)

3. Standpipe Piezometer 3 Principle: A standpipe piezometer is a relatively simple device used to measure pore water pressure. It consists of a perforated pipe (screen) installed in the ground, connected to a vertical riser pipe that extends above the ground surface. The water level in the riser pipe directly corresponds to the pore water pressure at the level of the perforated screen which is measured by a water level indicator. Components: Perforated pipe (slotted screen): Installed in the ground to allow water to enter the pipe. Riser pipe: Extends above the ground to measure water level. Water level indicator: A device to measure the water level in the riser pipe (e.g., digital water level sounder). Advantages & Limitation: Simple design and construction. Reliable for measuring static water levels. Susceptible to clogging. Manual readings are required. 3 Typical Image of a Water Level Indicator Probe

4. Vibrating Wire Piezometer Principle: A vibrating wire piezometer is a more advanced instrument for measuring pore water pressure. It operates on the principle that the frequency of vibration of a stretched wire is influenced by the applied tension. In this case, the tension in the wire is affected by the pressure exerted on a diaphragm by the pore water. Components: Stainless steel wire: Stretched under tension within a sealed housing. Cable: Connection from housing to the readout unit Diaphragm: Sensitive to pressure changes and connected to the vibrating wire. Electronic readout unit: Measures the frequency of the vibrating wire, which is directly related to the pore water pressure. Advantages & Limitation: High accuracy and precision. Rapid response time. Suitable for measuring both static and dynamic pressures. Automated data acquisition. Susceptible to damage from vibration or impact. Typical Image of a VWP Installation

5. Inclinometer Principle: An inclinometer measures the inclination or tilt of a soil mass relative to gravity. It's essentially a device that quantifies slope or deformation. Components: Casing: A long, slender tube installed in the ground. Probe: A device containing tilt sensors that is inserted into the casing. Electronic readout unit: Processes data from the probe and displays tilt measurements. Advantages & Limitation: Accurate measurement of lateral earth movements. Can be used to monitor slope stability. Requires careful installation and calibration. Sensitive to vibrations and external disturbances. Typical Image of a Probe and Readout Unit

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