Research On Settlement Law Of Highway Subgrade Considering Creep Characteristics Of High Fill

With the implementation of my country’s "One Belt,One Road" development strategy,the construction of high-grade highways has gradually shifted from plains to mountainous areas,and high-fill roadbeds have emerged.The high filling height and the large amount of filling of the high-filled subgrade make the settlement of the subgrade large,slow and stable,and it is prone to uneven settlement.this will cause diseases such as vertical and horizontal cracking,sliding or collapsing.The properties of roadbed fillers are special,especially the creep characteristics of the fillers are more complex,and have a significant impact on the settlement characteristics of the roadbed.Therefore,studying the settlement characteristics of high-filled roadbeds under the premise of considering the creep characteristics of fills has become one of the key topics in the field of highway engineering.Based on the existing research,this paper takes the high-fill roadbed project in a certain section of the "V"-shaped valley of the Dingxi-Lintao Expressway as the background,carry out indoor geotechnical tests such as one-dimensional consolidation creep test for subgrade fill,the strength characteristics and creep characteristics of subgrade fill are studied.The strength characteristics and creep characteristics of subgrade fill are studied.Using finite element software modeling and analysis,combined with on-site monitoring data,the settlement characteristics of high-fill roadbeds are studied when the creep effect of the fill is considered,it provides a theoretical reference for the calculation and prediction of post-construction settlement of the high-filled roadbed.The main conclusions are as follows:(1)Through mineral composition analysis test,particle analysis test,compaction test,triaxial CD test,etc.,the physical and mechanical parameters of subgrade fill are obtained.The strength characteristics of the fill are studied through triaxial tests.The greater the water content,the lower the shear strength;the greater the confining pressure,the greater the shear strength of the soil sample.(2)Through one-dimensional consolidation creep test,the influence of moisture content on the creep characteristics of subgrade fill is studied,the strain-time curve of subgrade fill is nonlinear.As the moisture content and vertical load increase,the strain of the specimen increases,and the creep effect is obvious,Increased time from the initial creep stage to the stable creep stage.(3)The stress-strain-time curve through the data of the secondary consolidation stage of the creep test,fit the creep parameters of the creep model.Take engineering examples as prototypes to establish simulation analysis of high-fill roadbed models,the settlement curve of each point at the subgrade isobath is in the shape of a "basin",the farther away from the central axis,the smaller the settlement;The higher the filling height of the subgrade,the greater the settlement of the subgrade and the lateral displacement of the filling body;Vertically along the center of the embankment,the maximum settlement of the roadbed occurred at 1/4 of the centerline of the roadbed.(4)The creep effect of the subgrade fill has a significant influence on the settlement of the subgrade,at the same time,the working-hour settlement of the subgrade when the creep effect is considered is greater than the working-hour settlement of the subgrade when the creep effect is not considered;The longer the consolidation time of the filling,the greater the settlement during working hours,the smaller the settlement after construction,and the more obvious the creep effect of the filling;The greater the water content,the greater the total settlement of any part of the roadbed during work and the greater the settlement after construction,and the more obvious the creep effect of the fill.(5)According to the on-site monitoring data,a relatively regular curve is obtained,the improved gray system method GM(1.1)model was selected to predict the post-construction settlement of the high-filled roadbed.One year later,the settlement predicted by the numerical model was 59.8mm,and the settlement predicted by the prediction model was 56.3mm;The settlement value of roadbed calculated by numerical simulation,on-site monitoring,and prediction model is basically the same.