An instrument for wetting-drying cycle of expansive soil under simulated loads and experimental research

Abstract EN

The alternating effect of rainfall and evaporation in nature causes great damage to the shear strength of expansive soil.

To study the effect of wetting-drying cycle experiencing loads on the strength of expansive soil, an instrument is developed in this paper, and its testing error is verified as well.

Helped by this instrument, specimens that experienced 0-6 cycles under OkPa, 5kPa, 15kPa, and 30kPa are carried out; direct shear test is performed for those samples.

The results show that the instrument accurately controls the water content (within 1%), simulating an actual cycle for soil at different depths.

Wetting-drying cycle shows a significant impact on the cohesion, although the friction angle is not sensitive to the cycles.

An additional parametric study suggests that the decrease of shear strength can be attributed to cracks caused by wetting-drying cycles.

The existence of load effectively restricts the shrinkage crack and the attenuation of shear strength and especially greatly inhibits the attenuation of cohesion.

Limited by load, specimen density also narrows the attenuation of shear strength to a certain extent.