| Popis: |
As a part of the large traffic diversion project in Umeå a new road is constructed tomake a connection between E12 and Hissjövägen. The contract is located in anagricultural area where the soil consists of a 6-14 meter deep sulphide clay. Thearea is also affected by a lower aquifer which contributes to artesian water.In the planning phase settlements were calculated using the software packageGeoSuite settlement but during the construction much larger settlements thanestimated were obtained. This study examines the possible causes of thesedifferences and evaluates if the software PLAXIS 2D produces results that betteragrees with field measurements than GeoSuite settlement.The study was performed by new calculations with both GeoSuite settlement andPLAXIS 2D for three sections, each with two different soil profiles with differentsoil characteristics. One interpretation of soil properties is intact from thepreviously used model utilized by the consultant. The other is a newinterpretation. The different models are similar, but depending on section themain difference is the pore pressure profile and permeability. In one of thesections, an unsuccessful CRS experiments was performed that lead to anincorrect value of the compression module.The results show that the main reason for the differences between measuredsettlement values in the field and the previously calculated values of settlement isthe shear deformation that the program GeoSuit settlement not takes intoaccount. These deformations are generated when the shear strength is reached.The reason for the high shear stresses obtained, is high embankments along withsoil properties such as: low permeability, long drainage pathways and the artesianwater in the area.Other factors that contributed to the larger field settlements are differences in thecompressive modulus caused by disturbed soil samples before CRS-trials andinappropriate selection of additional load calculation in GeoSuite settlement. Piledriving was also performed in the area, which probably have increased the porepressures and thereby also the risk of shear deformations. Validerat; 20130604 (global_studentproject_submitter) |
