Engineering Mechanics Characteristics Of Gobi Gravel Soil In Xinjiang And Stability Analysis Of High Fill Slope

The National Civil Transport Airport Layout Plan(2017)has planned the large-scale construction of the Northwest Airport Group in China.The unique geographical environment and dry climatic conditions in the northwest form a large Gobi area,where Gobi gravel soil was just suitable for filling material in airport construction.However,the Grab-Gravel soil gradation is not uniform,resulting in complex mechanical properties,which is difficult to be unified in theory,and has less experience in engineering applications.Hence,based on the reconstruction and expansion project of the northern part of Urumqi International Airport,the physical and mechanical properties of the coarse-grained soil of the Gobi gravel soil were analyzed through lab tests and the post-soil settlement deformation and stability of the Gobi gravel were explored,looking forward to providing guidance and assistance for this project and reference for indoor experiments and engineering application related to coarse-grained soil.The main work and conclusion are following:(1)A series of physical and mechanical tests were carried out on the Gobi gravel soil.Parameters including natural moisture content,salt content,particle gradation and large particle compressive strength were achieved.The effects of moisture content and coarse particle size on the compaction performance of Gobi gravel soil were studied by surface vibration compaction tests and the corresponding optimum moisture content and maximum dry density were obtained under the specific coarse particle size.(2)The effects of compaction degree and coarse particle size on the strength characteristics of the Gobi gravel soil was studied through large-scale triaxial test and the results of multi-level triaxial test were analyzed.The test results showed that the compaction degree and the coarse particle grading were internal factors while the confining pressure was an external factor affecting the strength of the Gobi gravel soil.In addition,the applicabilities of four common strength envelope were explored.(3)Referring to the lab tests results and field observation data,the vertical deformation characteristic of the Gobi gravel soil subgrade was analyzed.The settlement was simulated and predicted by hyperbola method and estimation formula method respectively and the differences and feasibility of two methods were analyzed.(4)Based on the practical application of the Gobi gravel soil high filling project,the stability of the high fill slope was analyzed by SLOPE/W,and the reinforcement effects of the grading measures of grading and reinforcement were analyzed.The reinforcement measures suitable for the high fill slope of Gobi gravel soil.