离心模型中测量基质吸力的微型传感器

Miniature transducers for matric suction measurement in centrifuge models

本文分析了3种应用于离心模型中测量非饱和土基质吸力的微型传感器。其中,电阻率微型传感器测量饱和度,通过土水特征曲线来求基质吸力,只能间接测量。热传导传感器相对体积较大,不受周围土体盐分的影响,适用于现场长期观测,但应用于离心模型还有待改进。改进的PDCR-81及其类似的微型张力计,体积微小,可直接测量非饱和土中的基质吸力。但其饱和程度会影响其测值,对饱和要求较高。为了进一步研究PDCR-81在离心模型试验中的测量基质吸力的可行性,笔者对PDCR-81做适当改进,应用其测量了非饱和土中吸力。试验发现,严格的饱和过程可以延长基质吸力稳定时间。

Three types of miniature transducers applied for centrifuge models electric resistivity probe is used tO determine the degree of saturation through are analyzed. The miniature which the matric suction can be obtained from the soil water characteristics curve. It can only be used for indirect measurement. The thermal conductivity transducer has a bigger size, is not subject to environmental salt and is suitable for longtime measurement of matric suction. Its application in centrifuge modeling should be further studied. The modified PDCR-81 or the like of miniature tensiometer is capable of measuring the matric suction directly in the unsaturated soils. However, the saturation of this type of tensiometer should be prepared strictly, because the saturation can affect their precision. In order to study the feasibility of applying PDCR-81 into centrifuge models, tests on matric suction have been conducted with modified PDCR-81 transducer in unsaturated soils. The test results show that the stabilization time may be prolonged after a strict saturation.