Taking Yunnan laterite as the research object

this paper studied the effects of different factors on the swell-shrink characteristics of Yunnan laterite and the influencing factors such as wetting-drying cycle time

wetting-drying cycle times and initial dry density were taken into account through the method of expansion and shrinkage test combined with image processing. The results showed that the expansion process of laterite can be divided into 3 stages: rapid expansion

slow expansion

and stable expansion. The contraction process could also be divided into 3 stages: slow contraction

rapid contraction

and stable contraction. With the increase of wetting time

the vertical expansion rate

moisture content

porosity and other expansive parameters of laterite increased as the “厂” type. The shrinkage parameters such as vertical shrinkage

transverse shrinkage

volume shrinkage and so on increased with the time of dewetting

showing the change of “S” type

and the moisture content and porosity decrease gradually. With the increase of humidification times

the stability of vertical expansion rate

the transverse expansion rate

and the volume expansion rate increased sharply first and then decreased slowly. With the increase of dehumidifying times

the vertical shrinkage

the transverse shrinkage

and the volume shrinkage increased firstly and then fluctuated slowly. With the increase of initial dry density

the vertical expansion rate

the vertical shrinkage rate

and the volume expansion rate increased

while the transverse expansion rate

transverse shrinkage rate

and volume shrinkage rate decreased.