3. Effect of drought on construction

3.1 Introduction

Clay soils, and in particular plastic clays that can swell when exposed to water, can suffer significant volume loss due to evapotranspiration caused by climatic and vegetation conditions affecting the soil. We know that that the more plastic a clay is, the higher the suction corresponding to its air entry point, which means that these clays can remain saturated even under fairly high suctions. We can thus estimate the relative settlement that a saturated clay with 20% water content and a grain density of 27 kN/m ³ would undergo under the effect of a 3% decrease in water content: $\frac{\text{Δ}H}{H_0}=\frac{\text{Δ}e}{1+e_0}=\frac{\frac{{\gamma }_s}{{\gamma }_w}\text{Δ}w}{1+\frac{{\gamma }_s}{{\gamma }_w}{w}_0}\approx \mathrm{5,3}\text{\%}$

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