A Preliminary study on construction of a high capacity tensiometer and its use in measurement of matrik suction in unsaturated soils

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2013

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Köksalan, Ali Okan

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Soil suction is one of the main state parameters that governs unsaturated soil behaviour. Tensiometers are the only type of probe that can measure soil suction directly, but only up to 90 kPa. In the past two decades, a new type of tensiometer with much greater measurement range (up to 2 MPa) has appeared in the literature. The measurement range (i.e. capacity) of a tensiometer is limited by (i) how well it is saturated, and (ii) the air entry value of its porous interface. In this study, the first high capacity tensiometer of Turkey was designed and built. For the purpose of increasing the measurement capacity of the tensiometers, a novel saturation setup that uses a hydraulic pressurization system with capacity of 10 MPa was designed and built. A vacuum-and-pressure saturation procedure was developed. To calibrate the 10 MPa pressure transducers that form the core of the tensiometers, a high-pressure calibration setup capable of pressurizing up to 11 MPa was designed and built. By varying designs of tensiometer bodies, porous interfaces and seals, ways of increasing the suction capacity are investigated. Over a dozen tensiometer design variations are developed, and tried by exposing to atmospheric evaporation. A maximum suction measurement of 870 kPa was achieved with a conventional design; however, none of the new designs were successful. 3 successful designs were also briefly tried on soil samples

Subject Keywords

Soil mechanics., Settlement of structures., Soil stabilization., Tensiometers., Measuring instruments.

URI

http://etd.lib.metu.edu.tr/upload/12615637/index.pdf
https://hdl.handle.net/11511/22347

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Graduate School of Natural and Applied Sciences, Thesis

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Citation Formats

A. O. Köksalan, “A Preliminary study on construction of a high capacity tensiometer and its use in measurement of matrik suction in unsaturated soils,” M.S. - Master of Science, Middle East Technical University, 2013.