Study On Stabilization Of Silt Subgrade: Theory And Application

For highway construction in the area of silt soil, a stabilizing method and appropriate stabilizing materials, which are dependent on the characteristics of silt, have to be investigated in order to satisfy the requirements of engineering. The deformation features of stabilized silt subgrade under traffic loading has also to be analyzed. This has important theoretical and practical meanings for highway engineering.Based on highway constructions of Jiangsu province, engineering characteristics of regional silt are investigated systematically through laboratory tests in this paper. From the points of silt strength improving, water stability, and anti-shrinkage property, the stabilizing mechanism is studied and the possible components of stabilizing material are proposed. The optimum ratio for individual components of high performance stabilizing agent (SEU-2) are obtained from laboratory tests, including preliminary selection tests, orthogonal tests, optimization test, comparison tests of multiple stabilizing materials, and microscopic tests of interaction between stabilizing agent and silt. According to full-scale field tests of silt subgrades stabilized with different agents, it is considered that the silt subgrade stabilized with 4 percent of SEU-2 has satisfying physical and mechanical properties and pavement performance. Considering the features of silt slope, the liquid stabilizing agent (SEU-1) has been successfully developed through laboratory and field tests. SEU-1 can prevent erosion of slope, and be helpful for plants growing. After the analyses of features of traffic loading, a new modified elasto-plastic model is proposed to describe the change pattern of accumulative deformation of soil under cyclic loading according to the concepts of yielding surface and loading surface. The corresponding program, which is compiled by FISH language in FLAC^3D, is used to calculate the 3D dynamic responses of stabilized silt subgrade under traffic loading and to discuss the effects of soil parameters on the deformation of subgrade. Finally, the deformation and stress in subgrade corresponding to different design schemes in Yan-Tong Highway are studied, and the optimal design scheme is proposed. The research results for this paper are as follows.(1) The fundamental characteristics of regional silt are investigated. From the points of gelling and filling effect of stabilized silt, the stabilization mechanism is studied. Through laboratory and field tests, a new stabilizing agent of silt (SEU-2) is developed successfully, which presents good physical and mechanical properties, pavement performance, and high performance-price ratio.(2) A new liquid stabilizing agent (SEU-1), which is suitable for silt slope protection, has been developed successfully. This agent can prevent erosion of slope, and is helpful for plants growing.(3) According to the fundamental features of traffic loading, a new modified elasto-plastic model is proposed to describe the deforming characteristics of soils under cyclic loading. A...