Three-Dimensional Structural Evolution and Multiscale and Micro-Macro Property Analysis in the Consolidation of Saturated Fine-Grained Soil

Saturated fine-grained soils have various compositions. In particular, the soil structural scale varies from nano-meter to macroscale. Micro properties can affect mechanical properties such as ground-bearing capacity. The exploration of quantitative micro properties and the quantitative relation between micro and macro evolutionary characteristics continues to challenge scientific research. In this study, both data constraint modelling (DCM) and multi-energy synchrotron X-ray μ-CT were used to realize the quantitative characterization of microstructure. Soil sample compositions are classified into pores, organic matter, and minerals. Then, the occurrence and three-dimensional multiscale evolutionary characteristics of soil samples are studied under different pressures based on substance compositions. Results show that the pore and mineral are mixed together to forming soil aggregates. A small amount of organic matter is distributed in the soil. Organic matter is mostly contained in pores or located at the junctions of pores and mineral clusters. The connectivity degree between pores decreases and that between minerals increases as pressure is increased from 0 to 1600kPa. When pressure is more than 400 kPa, macro pore clusters disappear and micro-nano pore clusters begin to appear. Pore morphology changes from large to small and dense. The soil microstructure changes irregularly when the pressure increases. The structural change in saturated fine-grained soil is related to the initial pore and mineral distribution and to consolidation pressure. Quantitative analysis between micro and macro properties suggests that the mechanical property of saturated fine-grained soil is closely related to those of micro and nanoscale pores and mineral aggregates. The methods in this study can provide a feasible theory for soil creep mechanism analysis. The proposed method is applicable for the analysis of the micro and macro properties of other engineering materials like concrete. © 2019, Editorial Board of Journal of Tianjin University(Science and Technology). All right reserved.