Test Characteristics Research On The Strength Of Remolded Loess With Different Water Cut Under Cyclic Loading

Loess is widely distributed in the northwestern part of China.Due to the deep groundwater depth in the northwestern region,the loess in this area is in an unsaturated state all year round.Their genesis is diverse,the composition is diverse,and the influencing factors are diverse.In particular,the dry and wet seasons in the northwest are distinct,the dry season is less,the saturation of the loess is lower,the rainfall in the rainy season increases,and the saturation of the loess also increases,especially under the influence of traffic loads,especially during the rainy season.The foundation of the bridge structure composed of unsaturated loess,the roadbed of high-speed railway,the foundation of building construction,earth dam and other projects will be unstable to scale,causing enormous casualties and economic losses.Therefore,the dynamic strength characteristics of unsaturated remolded loess under cyclic loading are studied,and the failure mechanism of unsaturated remolded loess under cyclic loading is analyzed.The highway subgrade and high-speed railway subgrade formed by loess in Lanzhou area and even the whole northwest region are analyzed.The construction,dynamic stability evaluation and disaster prevention and mitigation of bridge structure foundations are of great theoretical and engineering practical significance.The technical route of this paper is “conventional geotechnical test-unsaturated remolded loess soil water characteristic curve test-unsaturated remolded loess static strength testunsaturated remolded loess dynamic strength test”,and the experimental research is carried out centering on the technical route.It is decided to control the matric suction by controlling the water content indirectly,and to study the dynamic and static strength of unsaturated remolded loess,analyze the influencing factors of the dynamic strength of unsaturated remolded loess and the causes of this influence,and explore the dynamic strength characteristics of unsaturated remolded loess.The main research contents of this paper are summarized as follows:(1)The experiments of natural density and water content,compaction,liquid-plastic limit and permeability of loess used in this paper are carried out in turn.The basic physical characteristics of loess selected in this paper are analyzed..(2)The Fredlund SWCC instrument was used to test the soil water characteristic curve,and the soil water characteristic curve was drawn.The law of the matrix suction force changing with water content was summarized.The soil water characteristic curve was used to determine the soil sample required for the static three-axis test and the dynamic triaxial test.The amount of water.(3)The static triaxial tests were carried out on remolded loess with different water content.The test data were analyzed and the shear strength line was drawn.The static shear strength index under different water content was obtained.It was found that there was a positive correlation between water content and the static strength index of remolded loess.(4)Dynamic triaxial tests were carried out on remolded loess with different water content,and the water content of soil samples was the same as that of static triaxial tests.According to the experimental data,there is a negative correlation between water content and dynamic strength index.(5)The dynamic strength and static strength are compared and analyzed,and the relationship between the dynamic strength and the static strength is obtained.