Theoretical and experimental study of initial cracking mechanism of an expansive soil due to moisture-change |
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Authors: | Jun-hua Wu Jun-ping Yuan and Charles W W Ng |
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Affiliation: | [1]Key Laboratory of Ministry of Education for Geomechanics and Embankment Engineering, Hohai University, Nanjing 210098, China [2]Geotechnical Research Institute, Hohai University, Nanjing 210098, China [3]College of Civil Engineering and Architecture, Nanchang Hangkong University, Nanchang 330063, China [4]Department of Civil Engineering, Hong Kong University of Science and Technology, Kowloon, Hong Kong, China |
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Abstract: | Swelling and shrinkage due to moisture-change is one of the characteristics of the expansive soil, which is similar to the
behavior of most materials under thermal effect. If the deformation is restricted, stress in expansive soil is caused by the
swell-shrinking. The stress is defined as “moisture-change stress” and is adopted to analyze swell-shrinkage deformation based
on the elasticity mechanics theory. The state when the total stress becomes equal to the soil tensile strength is considered
as the cracking criterion as moisture-change increases. Then, the initial cracking mechanism due to evaporation is revealed
as follows: Different rates of moisture loss at different depths result in greater shrinkage deformation on the surface while
there is smaller shrinkage deformation at the underlayer in expansive soil; cracks will grow when the nonuniform shrinkage
deformation increases to a certain degree. A theoretical model is established, which may be used to calculate the stress caused
by moisture-change. The depth of initial cracks growing is predicted by the proposed model in expansive soil. A series of
laboratory tests are carried out by exposing expansive soil samples with different moisture-changes. The process of crack
propagation is investigated by resistivity method. The test results show good consistency with the predicted results by the
proposed theoretical model. |
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Keywords: | expansive soil swell-shrinking deformation moisture-change crack resistivity |
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