Abstract: By in-situ dynamic test on expansive soil section in high and low embankments of He-Ning High-speed Railway, their engineering characters under simulative dynamic loads are analyzed. It is verified that the principle of dynamic stress attenuation coefficient of both depth is alike; the elastic deformations of both depth’s embankments are 0.39 mm and 0.48 mm separately, which is allowable; the plastic deformations of both depth’s embankments are 0.7 mm and 1.5 mm separately; on the dry condition, combined dynamic rigidity coefficient of high embankment is about 317 MPa and 220 MPa after storm rainfall, while low embankment is 365 MPa nearly all the time, different modified soil thickness causes different dynamic rigidity coefficients.

Key words: expansive soil, embankment height, dynamic stress, deformation