Mechanics Responding Analysis On The Subgrade And Pavement Under The Condition Of Moistening Deformation Of Expansive Soil Cutting

The expansive soil is one of the most difficult problems in the field of engineering geology and unsaturated soil mechanics. As the imperfect engineering characteristics of expansive soil such as the strong expansive and shrinkage character, multi-crevice and strength reduced by dry-wet circulation and so on often cause the damage such as buckling, shatter of the slope of expansive soil and cracking, uneven heaving occurred in the pavement of the area of expansive soil, wider additional stress will be generates in the pavement, which will influence the long stability of pavement structure. And rainfall, especially long-lasting and heavy rainstorm has changed the pressure of the seepage and distribution of humidity field of the cutting. Moreover, it induces buckling damage of the cutting and the pavement damage, which makes great economic losses to the highway engineering.According to the typical geological characteristic of the Nan-you expressway, this paper builds the corresponding calculation model aiming at the cutting segment of K133+900; putting the situation when the construction is finished as the initial situation, using the seepage theory of non-saturated soil and adopting the analyzing software of finite element, carries on the transient seepage to expansive soil cutting under the rainfall situation; obtains the distribution of water pressure influent theory to analyze the transient influent in the expansive soil cut subgrade under rainfall situation, and obtains the distribution of pressure head and the adding volume distribution of pressure head in the cutting after different volumetric water.According to the result of the seepage analysis and non-uniform humidification deformation of expansive soil cutting which is calculated using the theory of humidity stress field, the paper obtains the non-uniform vertical deformation and lateral displacement of the slope of side slope of the sugrade top surface of expansive soil, and calculates the mechanics response of uneven vertical deformation of pavement structure to the embankment's top surface of expansive soil. The computing result indicates that the surfacing table and base table of pavement structure are equally subject to the function of tensile stress, which will build up damage to the pavement structure, and the longer of duration of rainfall, the bigger of the influence of pavement structure. Through adjusting the each level elastic modulus and layer thickness of the pavement structure, the paper obtains the more reasonable pavement structure.