(1. School of Civil Engineering，Southwest Jiaotong University，Chengdu，Sichuan 610031，China；2. Key Laboratory of Highway Engineering of Sichuan Province，Southwest Jiaotong University，Chengdu，Sichuan 610031，China；3. China Railway Eryuan Engineering Group Co.，Ltd.，Chengdu，Sichuan 610031，China)
Abstract：The deformation characteristics of the foundation of medium-strong expansive soil under low embankment upon soaking was studied for the construction of Yun-Gui high-speed railway. The field soaking tests of expansive soil foundation under the subgrade of different heights were carried out using the artificial soaking with sand holes，sand traps and sand cushion etc. applied together to have multidirectional soaking during the test. The deformation of the ground surface and the subgrade surface were measured during the stage of embankment construction，the steady stage after the construction and the artificial soaking stage. The measured results indicate that the curves of deformation of expansive soil foundation can be described as S-shaped curves from the beginning of subgrade filling to the end of artificial soaking. Along the cross-section of subgrade，the expansion variables can be decribed as “pan bottom” shaped distribution on the ground surface and as V-shaped distribution on the subgrade surface. The relative expansion of the ground surface decreases linearly with the increase of the height of embankment. The relative expansions of the ground surface are larger than those of the subgrade surface. The expansion of the ground surface became smaller and smaller as the height of subgrade increased. On the basis of these experimental results，the critical height of the subgrade that lead to the zero swelling at the ground surface is thus proposed to be the control value for the design of the embankment.
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2014, Vol. 33 
