Forced ventilated swell-shrink test for potential vertical expansive soil movement

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Allen, John Michael

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A practical method has been explored for determining the potential vertical movement in an expansive soil deposit during wetting and drying cycles. Currently, engineering practitioners are faced with using potentially inaccurate empirical methods or complicated and expensive laboratory testing combined with constitutive methods to determine expansive soil vertical movement. The proposed method is based on the use of forced ventilation to accelerate shrinkage while cyclically swelling and shrinking a soil specimen in a one-dimensional oedometer. The accelerated shrinkage reduces testing from over month to approximately 21 hours. The use of forced ventilation to induce specimen cracking was found to result in cracking similar to that observed in the field. The use of multiple swelling and shrinking cycles indicates that specimens come to equilibrium and follow the same swell-shrink path in three to four cycles. The results of the proposed method combined with seasonal moisture fluctuations allow the potential vertical movement to be estimated with a simple and practical test. The development of this test methodology improves the capability of engineers to compare laboratory work with field data


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