Study On Lateral Pressure Coefficient And Structure Of Q₃ Loess In Xi'an

In the northwestern region of China,the loess is widely distributed,Many scholars and experts have conducted extensive research on loess.With the advancement of the "Western Development Strategy" and "Belt and Road Construction".More in-depth and meticulous research is needed on the engineering characteristics of loess.Loess is a typical structural loess,its lateral pressure coefficient is a particularly important parameter in engineering,and its size is directly related to the stability of engineering structures.Therefore,in this paper,for the loess in Xi'an,we prepared undisturbed and reshaped samples with different water content,conducted K0 consolidation test and unconfined compressive strength test,and analyzed the K0 consolidation deformation characteristics of undisturbed(remodeled)loess at different depths.The lateral pressure coefficient K0 and the structural change law lead to the following conclusions:1.The change trend of the S-P curve of the undisturbed loess is divided into two types:hyperbolic combined form and concave function form,while the remodeled loess is divided into two forms:hyperbolic and concave function;The effect of deformation is small;the effect of deformation on the specimen after yielding is large.However,the influence of water content on the compression curve of remolded loess is greater than that of the original loess;at the same water content,the amount of compression deformation gradually decreases with the increase of dry density;in addition,calcareous nodules do not change the deformation law of loess,But will reduce the amount of deformation.2.The K0-?v curve of the undisturbed loess is divided into two trends:hyperbola and concave function.The remolded loess has a hyperbolic form;the K0 of the undisturbed(reshaped)loess increases with the increase of water content,but the water content The specific impact on K0 is related to the vertical stress.When the vertical stress is small,the influence range of water content on the remodeled sample K0 is larger than that of the original sample.As the vertical stress gradually increases,the influence range of the original sample K0 gradually catches up and exceeds the remodeled sample,and the original sample The rate at which K0 changes with water content increases first and then decreases,while the remodeling sample continues to decrease;calcareous nodules have a weakening effect on K0,and the weakening effect gradually decreases with increasing water content;intact(remodeling)The K0 gradually decreases with increasing dry density.3.The stress-strain curves of the undisturbed loess all show softening curves,but as the water content increases,the softening degree gradually decreases,the corresponding unconfined compressive strength gradually decreases,and the strain corresponding to the peak strength gradually decreases;The stress-strain curve of remolded loess is softened at low water content,and it is elastoplastic or weakly hardened when the water content is large.The unconfined compressive strength of remolded loess under the same water content is always smaller than that of undisturbed loess.After being reshaped and disturbed,loess decreases in strength but increases in strain.The calcareous nodules strengthen the structure of the loess by strengthening the bonding between the soil particles,the unconfined compressive strength increases,and the strength of the submerged structure increases.Analysis of the structure index of undisturbed loess shows that with the increase of depth,the initial structure of undisturbed loess gradually increases.By comparing and analyzing the K0 and the initial structural size of the original samples of different borrowing depths,it is concluded that the stronger the initial structural structure of the original loess,the smaller the K0 of the corresponding original samples.