Research On Engineering Characteristics Of Flood Silt Embankment Of Chicao Highway Under Vehicle Load

With the continuous development of our economy,the number of cars and trucks is also rising.With more traffic loads acting on the highway,it will cause unpredictable damage to the life and strength of the highway.How to deal with roadbed design on the basis of cost saving is particularly important in some stone barren areas.Combined with local conditions and the basic properties of Alluvial silt soil in Chicao Expressway area,it is urgent to study the engineering characteristics of Alluvial silt soil as subgrade filler,so as to satisfy the safety and stability of subgrade under vehicle load and provide theoretical basis for site construction.(1)The thesis relies on Chifeng to Caofeidian engineering section project topic.The engineering application characteristics and engineering characteristics of roadbed under vehicle dynamic load are studied by means of indoor conventional test,dynamic triaxial test,numerical simulation and field monitoring.The main research contents are as follows:(2)Conventional laboratory tests are carried out on the basic physical properties of the Alluvial silt soil,and the optimal moisture content and maximum dry density of the soil sample are obtained through screening tests to determine the particle gradation of the Alluvial silt soil and compaction tests.Dynamic triaxial test of soil was carried out to study the mechanical properties of soil under cyclic dynamic load.The influence law of dynamic characteristics of roadbed under automobile load under different working conditions(confining pressure,water content,dynamic load frequency,etc.)is studied experimentally.The dynamic stress and strain relationship model,the dynamic elastic modulus-strain relationship function mathematical model and the dynamic strength and frequency of action relationship diagram are fitted.The critical dynamic stress of soil under different conditions is obtained by triaxial cyclic loading test.(3)Established the action load analysis of the three-dimensional finite element model of the vehicle and road,and verified the reliability of the finite element model through the results of the dynamic three-axis simulation conversion data.The influence of dynamic stress level and Alluvial silt soil subgrade working area at different depths below the top of subgrade model under different working conditions(base thickness and modulus,vehicle moving speed,compacting degree,overload rate and water content)under vehicle load is analyzed.The subgrade settlement is simulated and analyzed under different conditions of compactness and moisture content.The overall descending distribution law of subgrade model under dynamic load was explored.(4)Combined with the field monitoring test,a control test is carried out on the roadbed of this project.The test shows that the settlement of the roadbed is larger in the center of the roadbed,and smaller on both sides of the roadbed.Compared with cement gravel subgrade,the subgrade tends to be stable around 24 days after the completion of construction,and the overall settlement is maintained at 14-16 mm.The actual monitoring of subgrade settlement is compared with the finite element simulation data and the indoor triaxial test data under the same working condition.It is found that the vertical settlement rate of the finite element data simulation and the indoor test is slightly larger than that of the field monitoring.There is a 0.18% difference between the vertical deformation and settlement rate of the triaxial test and the field monitoring data.In practical engineering requirements,finite element simulation data,indoor triaxial test and field monitoring of subgrade settlement can meet the engineering specifications.