| Summary: | 碩士 === 國立交通大學 === 土木工程學系 === 99 === The measurement of maritc suction (negative pore water pressure) in unsaturated soil can generally be divided into direct and indirect methods. The most popular diect method is tensiometer. The indirect method can include the thermal conductivity sensor. Athough capable of measure matric suction up to 1500kPa for extended amount of time, it lacks sensitivity and tends to deteriate, affected by temperature and requires a laboratory calibration prior to field application. It is possible to use tensiometer for measuring matric suction as high as 1500kPa. Due to cavitation, the measurement time is short under high suction. Also, in most cases, it is not possible to insert multiple sensors in the same borehole location. The aim of this research is to develop a penetrometion type tensiometer that can measure matric suction at multiple depths in the same borehole. Using the concept of BAT sampler, the penetrometer/tensiometer has the advantage of low cost, easy to operate and reach equilibrium with the surrounding soil quickly. Concurrent with the development of the penetrometer/tensiometer, the author fabricated a stress constrolled pressure plate device to obtain the 1D stress dependent soil water characteristic curve (SDSWCC) for tube soil samples taken from the field. The SDSWCC obtained from field measurements using the new penetrometer/tensiometer and laboratory tests were then compared.
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