The Research On Salty Soil Engineering Characteristics And Sand Dynamics Of Northern Weifang

It was widely distributed on the northern Weifang plains the salty soil andliquefiable silt-sand soil which had bad affects on engineering geology anddisadvantages on the engineering projects because of their particular statics anddynamics properties, so it is necessary to carry research on the special soil from thenorthern Weifang plains.In this paper, the research was carried on to collect and arrange the informationavailable about the northern Weifang plains, survey outdoor for about460km2, have thesoluble salt content test and divide the soil samples into groups according to the typesof content salt and the salt content. About90%was the salty soil, and only a little wasthe non-salty-soil. We took some samples and had experiments on the related propertiesindoor. According to the soluble salt content test, the porosity of the soil samples was0.64-0.84, the water content10.46%—25.48%, the water content average17.60%, thewas compression coefficient0.171—0.383MPa-1, the internal friction angle21.6°—26.8°, and the cohesion was0.91—23.66kPa. We also had the total salt content analysisand the X-ray diffraction test to find that the mineral content and material compositionwere diverse, and about76%of minerals was original. The salty soil in the study areahad many characteristics such as low shear strength and high compressibility.The salt heaving rate of chlorine saline soil in the study areas was0.5%—2%, thefrozen-heave rate0%—0.6%, and the salt and frost heaving of sulphate salty soil was0%—1.5%, the frozen-heave rate0%—0.5%. Because of the role of salt in the soil,with the temperature changes, both the chlorine salty soil and the sulphate salty soilshowed a heaving and thaw settlement phenomenon. The collapsibility coefficient ofchlorine saline soil was0.3-0.13and as for sulplate salty soil, it was0-0.12. Overall thecollapsibility of chlorine saline soil was stronger than that of sulplate salty soil, eventhe collapsibility coefficient.We also carried on the direct shear test on the salty soil samples under the samewater content but different salt content. The test presented that as the salt content increased in the range of0%—6%, cohesion also increased, internal friction angleincreased first and then decreased slightly, and the shear strength of the soil presenteddecrease trend on the whole. After direct sheared, the soil samples had SEM. Combinedwith the changes of microstructure, we could explain the regular law that the intensityof direct shear changed with the salt content under certain moisture conditions.Dynamic triaxial test of the liquefiable silt-sand soil from northern Weifang plainswas carried on indoor for the related statics dynamics properties such as dynamicstrength, dynamic shear strength and dynamic shear strain to analysis the relationshipsbetween dynamic shear modulus and dynamic shear strain as well as the relationshipsbetween damping ratio and dynamic shear modulus.By anglicizing the results of dynamic triaxial test, we got equations on liquefactionabout relative compactness, average diameter and dynamic stress ratio by usingliquefaction phenomenon when=10、20、30longing for distinguishing the saltysoil liquefaction from the study areas. For7earthquake magnitude, when was10,the equation was6.21x2-163.68y2+16.76y+z-5.85=0. For8earthquake magnitude,when was20, the equation was0.0894x2-5.052y-z+0.642=0. For9earthquake magnitude, when was30, the equation was0.0894x2-5.052y-z+0.642=0.