The Study on Swelling Characteristic of the Weak Expansive Soil

• 1、Three Gorges Research Center for Geo-hazard, Ministry of Education,China University of Geosciences, WuHan 430074
• 2、The faculty of engineering,China university of Geosciences,Wuhan 430074
• 3、Three Gorges Research Center for Geo-hazard, Ministry of Education,China University of Geosciences,Wuhan 430074

Abstract：The expansive soil in Luwangfen of Xinxiang in Henan is from the Tertiary marlite weathering, which main clay mineral is kaolinite,and owns weak expansive characteristic which is affected largly by the pore structure. In order to study the expansive characteristic of weak expansive soil in testing section, this article studies importly from the expansion with loads,swelling stress and expansion-contraction cycle,and gets the different conclusions from oher expansive soil:1) when the initial density is smaller and overlying loads are larger than expansive stress, the remolded weak expansive soil doesn't occur expansion,but collapsible phenomenon after immering water; when the initial dry density is more than the compaction degree 96%, even when the overlying loads are larger than expansive stress ,the remolded weak expansive soil dosen't occur collapsible phenomenon , and the swelling deformation tends to a constant value with the overlying loads increasing; 2) The swelling stress of the weak expansive soil in testing section first increases then decreases with the initial water content increasing, and occurs the expansive stress peak;3) With the the expansion-contraction recurring series increasing, the expansion-contraction characteristics of the weak expansive soil decrease rapidly, and the expansion-contraction deformation tends to be stabilized when the cycle progression reaches to 4. The expansive characteristics above these three areas show fully that the swelling characteristics of the weak expansive soil is related closely to the pore structure.

Keywords： geotechniacl enginnering weak expansive soil expansive characteristics collapsible phenomenon swelling stress expansion-contraction cycle