The Slope Stability Analysis Of Basalt Residual Soil In Guizhou

Basalt weathering of soil is widely distributed in most areas of China. With the developmentof economy and the formulation of national western program, the contact of basalt will be moreand more common in the process of infrastructure construction in the future. And then the studyon the basic distribution characteristics, mechanical properties, hydraulic characteristics and thefactor which effect the stability of soil slope is a significant demand of national infrastructureconstruction.Take the Emeishan basalt which is widely distributed in Guizhou as an example, studyengineering properties of basalt residual soil and deformation failure modes of the slope. It canbe discovered that the soil slop can be divided into reddish brown soil, brown soil and darkbrown soil by the investigation on the representative slop along the expressway between theHezhang County of Bijie city and Weining. The problem of slop stability of basalt area oftenoccurs in the interface of secondary red soil and residual red soil. So this paper selected the redbrown basalt residual soil as the main research object, and finite element software’s applicabilityin geotechnical engineering was used to simulate the failure mode of basalt residual soil slope.The main research contents and conclusions of this paper are as follows:1. By surveying the basalt residual soil in Guizhou and collecting the relevant data relyingon the construction of Bi Wei highway, the basic distribution features was preliminarilyunderstood, and the basic mechanical properties and hydraulic conductivity characteristics ofbasalt residual soil were also comprehended. Because the red brown residual soil has large voidratio, high water content, high specific gravity, weak expansibility and easy disintegratingproperties, the physical property of red brown residual soil is poor, which leads a large numberof landslide in basalt area.2. Strength reduction FEM was used to analysis the basalt residual soil slope’s stability,selected a section of the project as the research object, and the influence of factors such as theslope angle, soil dilatancy angle and the model grid division on the stability of basalt residualsoil slope was analysised. Results of calculation examples showed that: the decrease of the slopeangle can improve the safety factor of slope; increase the dilatancy angle can also increase theslope safety factor, but with the angle of dilatancy increasing, the improving velocity of thesafety factor is decreasing; with the increasing of the grid density, slope safety factor is reducedgradually, namely the mesh is smaller and the calculation results is more accurate.3. Using the finite FEM combined fluid-solid coupling theory to study the basalt residualsoil slope under rainfall infiltration failure mode. The results show that: at the beginning ofrainfall infiltration, the matrix suction of residual soil on the surface of slope is decreased, but later with the rainfall’s decreasing or stop, matrix suction of the surface of slope is graduallyrecovering; in the process of rainfall infiltration, the slope sliding deformation trend is visiblebecause the plastic deformation is the first to occur at the toe, and maximum of the horizontaldisplacement also appeared at the foot of the slope, the sliding deformation tendency of the slopeis visible in the process of rainfall infiltration; under the action of rainfall infiltration,slope instability phenomenon mainly occurs at shallow slope. So in this kind of slope protectionshould pay attention to drainage measures on slope.4. Using the finite difference with the strength reduction method to simulate the cuttingslope stability of basalt residual soil under different support. Using varietal supporting schemewhich combining the retaining wall, prestressed anchor cable and anchor net shotcrete toreinforce under the extreme rainfall condition. The simulation results could meet the requirementof the standards, namely the supporting scheme is feasible. As the anchoring measures areweakened, stable effect has different degree of reduction.