Numerical simulation of the triaxial test of coal measure expansive soil distributed along the highways in Pingxiang District, Jiangxi, was carried out by means of discrete particle flow, during which the macromechanical properties and the formation and developmental patterns of shear displacement field of the coal measure expansive soil were studied from a mesoscopic perspective. The result showed that the macroscopic stress and strain of test specimens can be significantly influenced by the interparticle friction coefficient of the coal measure expansive soil. Peak value of the deviatoric stress of test specimens increased with increasing friction coefficient, and before reaching the deviatoric stress peak value, the stress-strain relationship of the soil body basically presented a linear variation trend; the soil interparticle contact stiffness varied hyperbolically with the deviatoric stress peak value of test specimens, and the increasing contact stiffness ratio led to a gradual decrease of the deviatoric stress peak value but had only a small impact on the residual strength of test specimens; confining pressure was found to have remarkable influence on both the deviatoric stress peak value and the residual strength of test specimens; when the experimental confining pressure increased from 0.2 MPa to 1.2 MPa, the deviatoric stress peak value and the residual strength of test specimens increased by 2.14 times and 5.11 times, respectively. This paper reveals the macroinstability and failure mechanism of coal measure expansive soil from a microperspective.
With coal measure soil side slope in Jiangxi’s Pingxiang-Lianhua Expressway selected as the research object, GeoStudio, a finite element seepage analysis application, was adopted for numerical simulation on the variation pattern of volumetric moisture content in the side slope in rainfall as well as its spatial distribution characteristics. The results show that rainfall infiltration mainly influences the surface layer of the side slope and that its influence decreases with the increase of depth. The volumetric moisture content of undisturbed coal measure soil remains basically unchanged under the weathered layer. When soil mass permeability coefficient is less than rainfall intensity, the rainwater permeates quickly in the outermost layer of a weathering zone, but exerts a minor influence. When it is larger than the rainfall intensity, rainfall permeates slowly but exerts a major influence. When rainfall intensity reaches 8.33 ×10−7 m/s, soil moisture contents in the superficial layers of the slope toe and halfway up the slope surface become saturated. The saturation depth is 80% of the weathered layer. When the rainfall intensity reaches 1.1 ×10−6 m/s, it exerts a more extensive influence on the saturation area in the side slope, but the corresponding affected depth is only 50% of that in the weathered layer.
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