Research On The Influence Of The Swelling Force On The Stability Of The Expansive Soil Slope

Expansive soil is the special geologic body with expansive and shrinkage property, which is usual fractured and over-consolidated. The existence of expansive soil often causes catastrophic failure of geotechnical engineering, especially in slope engineering. Thus much attention to pay on the problems of expansive soil is necessary. This thesis studies the influence of swelling force on the stability of expansive soil slopes through laboratory expansive properties tests, artificial rainfall simulation tests on slope model and numerical simulation. Based on the study of expansive properties, this thesis discusses the failure mode and mechanism of expensive soil slope, presents a reasonable measure to execute stability analysis. The main contents and conclusions are listed as follows.(1) Based on the scope and key purposes of the study, vast scale documentations are referred, the status and insufficiency of the research on expansive soil problems is also summarized.(2) The expansive properties are studied via laboratory swelling strain and swelling force test. By regression analysis of laboratory test result, the quantitative relationship between swelling force and dry density, swelling deformation and initial moisture content is developed, and the sensitivity of swelling force on these factors is subsequently discussed.(3) The process of penetration and the deformation of slope during rainfall test are carefully studied. The conclusion that the cyclic process of rainfall and evaporation accelerates the slope deformation and finally results in the failure of expansive soil slope is drawn. The rainfall test also shows that the failure of expansive soil slope often happens in top soil and characterizes by traction failure.(4) A numerical stability analysis measure, which is more applicable to expansive soil slope, is discussed. The swelling force is introduced into the finite program for stability analysis of slope, with temperature field simulating moisture field. The results of the numerical simulation coincide well with those of artificial rainfall model test.