Experimental Study on Multi-stage Loess Slope Centrifuge Model Under Heavy Rainfall
To investigate the deformation and stability of multi-stage loess slopes under heavy rainfall,the rainfall simulation device mounted on centrifuge was designed.Taking the in-construction multi-stage ultra-high loess slope of Wuqi-Huachi expressway as the prototype,the centrifuge model tests were conducted to study the temporal variations in moisture content,soil pressure,and displacement of multi-stage loess slopes under rainfall.The comparative analysis was conducted to evaluate the influence of pre-existing joints on the loess slopes stability.The result indicates that the volumetric moisture content of slope surface soil layer rapidly increases under heavy rainfall,forming the transient saturation zone.During the infiltration phase,the wet front continuously moves downward,and the internal pore water infiltrates towards the slope bottom under the gravity,with the fastest infiltration rate at the slope toe and the slowest in the middle of slope surface,resulting in a reduction of approximately 6%in volumetric moisture content compared with the saturated state.The soil pressure on slope body is jointly influenced by the soil moisture content and the surface soil layer erosion,showing the slow growth during rainfall phase and the rapid decline during erosion phase.Compared with the slopes without joints,the presence of joints provides the preferential flow channels for rainwater infiltration,accelerating the downward infiltration rate.The slopes with joints are more easily eroded by rainfall,exhibiting a more pronounced increase in settlement growth rate and a greater reduction in soil pressure.The settlement at slope top with joints increases by approximately 20%compared with the slopes without joints after rainfall.Overall,the stability of multi-stage loess slopes under heavy rainfall is satisfactory.Under the combined effects of rainfall splash erosion and runoff scouring,the deformation failure mode induced by rainfall in multi-tiered loess slopes manifests as slip erosion,primarily concentrated at the slope toe and the surface of first step.Therefore,the slope surface and slope foot protection should be strengthened in practical engineering.
road engineeringdeformation rulecentrifuge model testloess slopeheavy rainfall
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