Experiment Research And Numerical Simulation For Regularity Of Moisture Migration In Embankment

With the highway construction gradually extended to the central and western mountains of our country, there is a large number of embankments with tall filling and deep excavation. The problem of decreasing post-construction settlement of embankment should be solved. Except that already was clear about, such as the embankment construction methods, the construction compaction insufficiency and the actual driving load, the moisture migration in embankment soil is also a main reason causing the post-construction settlement of embankment. Presently, although there is the certain research to moisture migration in unsaturated soil, but the solution method of unsaturated soil hydraulic parameters is still difficult to form the unification, and the research of the migration process and the migration regularity is still waiting for further consummating.In combination with the construction of embankment for Xiangtan-Hengyang expressway Hunan province, the moisture migration regularity of the typical packing in embankment is systematically studied in this paper. Firstly, based on the principle of tensiometer, a series of reequipment is carried on, the measuremented methods of the matrix suction is studied. Secondly, in combination with the PSD and the fractal theory of the packing soil samples, the PSD fractal dimension was obtained. Based on the Menger Sponge model, applling the bundle of capillary tubes model to SWCC, the matrix suction funtion expression of the packing soil is derivated. Through contrast and analysis the computed result and the actual result, it is shown that the test installation and theoretical analysis is exact. Based on moisture migrating process in unsaturated soil, designing the moisture migrating test in one-dimensional compacted soil column, the function expression of unsaturated hydraulic conductivities are determinated. Thirdly, the soil compacted column test under the condition of different flow border is designed, and the moisture migration regularity and the relationship among the boundary conditions , the degree of compaction and the regularity are studied .The numerical simulation of the front test with FEM software is carried out. The moisture content in the soil column are quite consistant with the experiment result and theoretical analysis result, which illuminate the Credibility of numerical simulation by FEM software to the problem of moisture migration in unsaturated soil. Finally, 2D FEM model of the embankment is established. The numerical simulation of the moisture migration regularity under the condition of natural weather in embankment is carried out, and the impaction of slope grass cover to the moisture migration regularity in embankment is further explored.