Study On Strength Characteristics Of Loess In Different Regions

With the development strategy of the country's western development and the promotion and implementation of the “Belt and Road”,human engineering activities in the loess region of Northwest China have become more frequent,and the activity area is more extensive.Many loess engineering problems have emerged,and the ecological environment of the loess region itself is fragile.Hair,so it is urgent to study and analyze the special soil of loess.Due to the wide distribution of loess in China and the different sedimentary environments,there are also significant differences in the structure,material composition and mechanical properties of the loess layer in China.Many scholars have carried out research and analysis on the distribution,genesis,material composition,strength and deformation of loess.A large number of research results have been widely applied to engineering practice and disaster prevention and mitigation in the loess area.For the study of loess deformation and strength mechanical characteristics,most of them are based on a certain fixed area.Based on the predecessors,ICU experiments are carried out on undisturbed loess in different areas.The CU experiment is carried out on loess mixed with different regions and different clay minerals and nano materials.The ring shear test was carried out in different areas and different illite mixed loess.The main conclusions are as follows:(1)The saturated undisturbed loess in different regions showed strong strain softening characteristics,and the peak intensity appeared in the axial strain 1-3%.The effective shear strength parameters c' and ?' of the saturated undisturbed loess in different regions are different,and the effective internal friction angle varies little in each region,and the maximum and minimum differences are 1.02 degrees.The order of effective cohesion is: Xiangyang>Xiji>Lanzhou,the law is that the effective cohesive force increases with the increase of cosmid content.The larger the plasticity index of loess,the lower the M,and the corresponding M value decreases with the increase of clay content.(2)With the increase of clay content,the peak intensity law is: under low confining pressure,the peak strength increases with the increase of clay content.Under high confining pressure,the peak intensity law develops toward V-shape.The peak intensity decreases first and then increases.The overall trend of effective internal friction angle of loess in different regions is as follows: the effective internal friction angle decreases with the increase of clay content.(3)The change of effective cohesion of loess with illite,kaolinite and nano-silica and loess in different regions: with the increase of clay content,illite,kaolinite and nano-silica,soil The effective cohesion of the body is increasing.The effective cohesion increase mode is divided into three stages: growth-stable-growth.The illite content of clay minerals in loess is the largest proportion of clay minerals.The strength of loess in different areas and the shear strength and shear strength parameters of illite loess samples are the same.It can be inferred that the change of loess strength in different areas is mainly from illite.The stone content is determined.(4)The shear strength of the ring shear test under the vertical pressure of 200 kPa is consistent with the shear strength law of the three-axis experimental confining pressure of 200 kPa.The order of residual strength is: Xiangyang>Gansu>Qingyang>Yan'an>Xiji>Yulin.As the illite content increases,the residual strength of the soil increases.