Research On Regularity Of Moisture Migration And Formation Mechanism Of Differential Settlement In Semi-filled And Semi-excavated Embankment

Moisture migration is the fundamental questions of non-saturated soil. rainfall infiltration, evaporation, groundwater level changes and so on in the role of boundary conditions, so that the unsaturated soil zone changes, the moisture field of non-saturated internal soil will re-distribute, the suction field of soil also changes. The surface soil dry-shrinkage and cracks with moisture content reducing, collapses with increasing, the soil of unsaturated zone occurres such as rebound and compressed deformation. A semi-filled and semi-excavated embankment belongs to the scope of unsaturated soils, due to their cross-section particularity, difference of soil materials and boundary complexity, with the change of boundary conditions and external loads, change of moisture content of internal subgrade soil arises from non-uniform deformation, and causes the road diseases. Because of the complexity of the unsaturated soil, the differential deformation issues need to be further study.The purpose of this paper puts a typical roadbed-filling in Hunan Province as the research object to do a systematic study of the non-saturated water movement law. First of all, do the design of column of soil testing about fill soil and the excavation of the soil, analyze the law of water movement of soil column at different infiltration angle, head height ,degree of compaction and under the conditions of the underwater level; and gets the relationship between the infiltration length and the infiltration head , time, infiltration capacity and the relationship between the wetting front x fand the time t ; the design of air-dry soil column moisture absorption test, the changes laws of wetting front with time and the moisture absorption after hygroscopic will be get, and obtained distribution function of the moisture rate of the soil column through the fitting curve. Followed for the particularity of the semi-filled and semi-excavated Embankment apply the wetting deformation mechanism to analyze wet slaking settlement of embankment soil under wetting; apply non-saturated fluid-solid coupling mechanism to analyze the water movement and deformation laws under a different rainfall lasted, intensity, and rain-type and the underwater level. Finally, use Geo-Studio Series software to set up model of a typical cross-section of the semi-filled and semi-excavated embankment in Hunan highway, analyze the law of moisture migration and differential settlement of the subgrade under the conditions of natural weather conditions and ground water changes, thus the control of post-settlement, improvement of construction technology of the semi-filled and semi-excavated Embankment, improved the drainage system provides the basis.