Micromechanical characteristics of collapsible loess and its subgrade settlement law
Relying on the loess subgrade reconstruction and expansion project of Shuozhou South Ring Road,based on the scanning electron microscope test and Grain flow numerical simulation analysis,the microstructure characteristics and stress changes of col-lapsible loess caused by the difference of porosity were studied microcosmically.A three-dimensional model of construction mechan-ics for collapsible loess highway roadbed was established using macroscopic numerical calculation methods.The settlement law of collapsible loess roadbed in highway reconstruction and expansion projects was studied macroscopically,and the effect of roadbed parameters on uneven settlement deformation of new and old roadbeds was explored.The research results were indicated that collaps-ible loess particles were mainly divided into loose particles and agglomerates,and their particle contact relationships mainly includ-ed:support contact,inlaid contact,and dispersed distribution.Among them,the support contact structure was most affected by the moisture content.Under different confining pressure conditions,collapsible loess samples with different porosities went through four stages of development during the loading process,and the porosity had a significant impact on the peak shear strength and residual strength of collapsible loess.The maximum settlement and deformation of both new and old roadbeds were affected by the widening width of the roadbed and the depth of the excavation,and maintain a relationship of equal increase and decrease.The foundation strength was higher,and the settlement deformation of the new and old roadbeds was smaller.The groundwater level was higher,and the collapsibility of loess was more obvious,and the settlement of new and old roadbeds was greater.The higher the groundwater level,the more obvious the collapsibility of loess,and the greater the uneven settlement of new and old roadbed.
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