Slope stability problems related with the swelling diatomite are met during the construction of Baoshan-Tengchong highway in Yunnan province. After field investigation of the typical geological sections and laboratory tests of composition

microstructure and mechanical properties on the samples from Wuhe town

Mangbang town

Tuantian town of Tengchong county

Yunnan province

it is revealed that the Neogene diatomite in the Mangbang formation is a type of clayey diatomite with rich swelling clay minerals

and belongs to very soft swelling rock. Natural clayey diatomite samples have strong structural properties

which lead to the relationship between their physical properties and mechanical properties against the traditional rock/soil mechanics laws. For example

the samples have void ratio up to 2.20-2.78

liquid index 0.66-2.73

while their uniaxial compressive strength can be up to 1.09-2.11 MPa. Comprehensive researches indicate that the occurred geo-hazards including landslides and weather-flaking of clayey diatomite slope along the Baoshan-Tengchong highway are closely related to their engineering properties.