Study On The Interaction Between Unsaturated Expansive Soils And Structure

Expansive soils, mainly composed of strong hydrophilic clay minerals, are of remarkable shrink-swell properties. The volume of an expansive soil can expand when it absorbs water and shrink when it loses water. Thus, it can exert destructive pressure to buildings with long potential dangers. Therefore it is of great importance to study the interaction between expansive soils and structures. A new device and A new system are designed to measure the earth pressure in centrifuge. Then Studies on the interaction between unsaturated expansive clay and rigidity retaining wall are carried out.A series of experiments are accomplished with filled expansive soil of different initial dry density and water content. Through controlling soak conditions, this paper observes the swelling of the expansive soil when it absorb water, discusses the distribution of earth pressure at rest before and after soak. Matric Suction of soil is measured by filter paper. And a linear relationship at semi-logarithmic coordinate is find out, which is used in the analyses afterwards.This paper analyses earth pressure of unsaturated expansive soil at rest with consideration of elastic equilibrium within a soil mass and suction theory. Twocoefficients of earth pressure at rest are defined, One is k_σ, which is related to the overburden pressure σ_v, The other is k_s, which is related to matric suction u_s.Using these two coefficients, theoretical analysis is similar to the experimental results. This analytical method is suitable to different soak conditions. When the filled expansive clay is sufficiently soaked, expansive force is convenient to analyse. The coefficient changes with dry density. For the same dry density, the coefficient doesn't change obviously.