Long-term Stability Study On Highway Roadbed In Coastal Water Net Area

The highway subgrade bear long-term traffic loads and influence from other natural factors. Under the circumstances, soil strength characteristics degenerate gradually, and eventually they will lead to damage of subgrade, unevenness and even crack of pavement. All of these will affect the performance of the highway. Based on the Cang-Huang highway engineering, in coastal water net area, in hebei province, the dynamic, static strength properties and long-term stability of subgrade filling were researched in these dissertation, with the ideas of theoretical analysis and experimental research. The main research results are as follows:(1) The water-soil characteristic curve in coastal water net area of soil subgrade filling was put forward, and the influence law of roadbed strength from moisture transfer was revealed.(2) The performance decay laws of subgrade filling were studied based on the rain infiltration and evaporation, groundwater capillary function and dry-wet cycling condition. The influence law of the subgrade soil strength and deformation characteristics were revealed with the cycle times.(3) The strength and deformation of subgrade filling and lime improved soil were studied based on a lot of static and dynamic triaxial test. The subgrade engineering characteristics and performance decay laws were put forward with the water content.(4) The vertical distribution of the traffic load in embankment structure were analyzed. The engineering characterics of subgrade in coastal water net area were analyzed under traffic load, according to the 3D finite element calculation model of dynamic traffic cyclic loading. The subgrade settlement coming from the moisture content changes under traffic cyclic loads was revealed. The corresponding technical countermeasures was put forward and the long-term stability of subgrade was solved.