Model Tests And Numerical Study For Engineering Properties Of Soft Subsoil With Upper Crust

During the construction in Chinese littoral and inland areas, it was always found that there been one layer of crust with higher strength and lower compression up on the soft clay. If this layer of crust can be reasonably used, it will greatly decrease the project cost. However, the working mechanism of crust and its load-deformation feature has not yet been studied deeply and systematically. In the real projects, the function of crust was always ignored, and so caused great waste. So, in this paper, the engineering features of stress distribution, load-deformation, consolidation settlement and so all, will be analyzed systematically by means of indoor model tests and numerical study.At first, the stress distribution characteristic of subsoil with upper crust was studied by FEM method. And the effects of different parameters (the thickness of crust, loading width, rigidness of crust and Poisson's ratio) on stress distribution were gained. Then, a set of orthogonal indoor model tests were carried out, and also elasto-plastic analysis by FEM was performed to study the load-bearing and deformation features of this kind of subsoil and the effects of different parameters on its failure mode, and some qualitative and quantitative conclusion were achieved.In addition, effects of crust on soil consolidation settlement were seldom studied by domestic and abroad researchers. In this research project, an one dimensional finite element model and also a plane strain finite element model was developed in ABAQUS program to analyze the consolidation settlement features of this kind of subsoil. During the analysis, the cam-clay model was used and the nonlinear feature was considered, to describe the real properties of subsoil. Some rules and laws of consolidation settlement were concluded.In the finality, further studies required by these problems are discussed.