| The time of primary consolidation settlement can be a critical factor for the construction of embankments over soft, thick, compressible soils. Prefabricated vertical (PV) drains are often used to effectively shorten the drainage path, and thus, reduce the time of primary consolidation settlement. Measuring the horizontal drainage properties of fine-grained soils is therefore important to understanding the overall settlement behavior, and being able to accurately estimate the time associated with primary consolidation settlement. Current methodologies for obtaining the horizontal drainage properties of fine-grained soils include, (1) back-calculation of field data using the Asaoka graphical method, (2) piezocone (CPTU) pore pressure dissipation test, (3) laboratory Rowe Cell, and (4) directly measuring in situ. This dissertation introduces a new technique, using multielement flow technology, for measuring the horizontal permeability of a soil in situ. Numerical modeling and bench scale testing of the prototype multiflow permeameter are included. An evaluation and comparison of the other methodologies is also provided. Furthermore, techniques for better estimating the time-rate of settlement of multilayered foundation soils with different consolidation rates, including using magnet extensometers and the finite difference method, are discussed. Finally, a case history identifying the primary consolidation and secondary settlement rates for different construction technologies employed at soft soil sites during the I-15 Reconstruction Project in Salt Lake City, Utah is given. |
