Stability Analysis of Embankment Slope Considering Water Absorption and Softening of Subgrade Expansive Soil

Abstract

With the rapid development of road engineering today, a large number of high-grade highways need to pass through expansive soil distribution areas. At present, the research on expansive soil slope mainly focuses on the newly excavated cutting slope. However, according to engineering experience, a landslide of fill embankment on expansive soil foundation is also very common. The expansive soil layer is heterogeneous. There are many weak intercalations or large fissures under the ground, which are generally parallel to the trend, with low strength and high permeability. After rainfall, the strength of the weak interlayer and large fissures will be further reduced after moisture absorption, and the sliding surface is easily formed under the load of filler, which is the main factor inducing embankment landslide. On the basis of landslide investigation and a laboratory test, a FORTRAN calculation program is developed in this paper, which can comprehensively consider the special moisture absorption and softening characteristics of expansive soil. Taking a high fill embankment slope with a soft interlayer in the Baoshan area of Yunnan Province as an example, the stability and instability characteristics of the fill slope on the expansive soil foundation are analyzed, and the influence of moisture absorption and softening on the expansive soil slope is emphatically discussed. Finally, this paper puts forward the reinforcement method of the high fill embankment slope on the soft expansive soil foundation, which is proven to have a good reinforcement effect through calculation analysis and field practice. For expansive soil foundation with weak interlayer, it is better to directly reinforce the weak layer through rigid piles.

Rainfall Scouring Mechanism of the High-Speed Railway Subgrade Slope with Coarse-Grained Soil

“…(2) When the water flow satisfies the Bernoulli principle, and the soil particles leave the slope height relative to three times the particle size, the uplifting force basically disappears; (3) The intergranular action, charge gravity, bite force, cementation force, and cohesion of soil particles and shear strength parameters are uniformly simplified to adhesion; (4) The surface infiltration conditions of the slope surface are good, and the infiltration pressure is consistent with the infiltration direction; (5) The direction of rainfall is the same as the direction of gravity; (6) When the critical start of scouring, the friction resistance flow rate is a fixed value; (7) When the critical start of scouring, the friction coefficient is a constant fixed value; (8) The critical starting of scouring is static; (9) The slope erosion is a strong turbulent effect, and the viscosity of the water flow is not considered; (10) The length of turbulence mixing can be determined using Carmen's turbulence similarity hypothesis.…”

“…Rainfall erosion often happens on the slope surface, such as sheet erosion and rills. As the continuous and multiple scouring, erosion will further develop into the interior of the subgrade, resulting in landslides [8][9][10]. Therefore, the erosion failure of the subgrade slope which may lead to serious security risks should be quantitatively studied.…”

Research on Landslide Hydrology and Hydrogeological Disaster Monitoring

“…The fourth paper [9] focused on seepage analysis on a road slope of fill embankment on an expansive soil foundation in Baoshan City, Yunnan Province, China. The expansive soil was heterogeneous due to the existence of weak intercalations and large fissures, which caused low strength and high permeability.…”

Optimal screening method for dosage of calcium-based nanosilica modified expansive soils improver based on cost-effectiveness

“…Expansive soil often causes subgrade damage, slope instability, and other engineering geological IOP Publishing doi:10.1088/1755-1315/1336/1/012019 2 problems due to increase in water absorption and dehydration shrinkage of clay minerals [1], [2]. The chemical improvement method is often used to treat expansive soil in practical engineering.…”