Deformationer kring spont: Jämförelse mellan fältmätning och FEM-simulering
Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
Settlements in soil around sheet pile constructions, can during construction, cause major problems in the surrounding buildings by endanger the safety and be a costly factor as well. Settlements and deformation in soil are predicted usually with table values from empirical expressions with respect to design, soil type, etc. It is also possible to numerically model the deformations in a finite element simulation.On behalf of WSP-Civils a sheet pile construction at Skanska’s project “Nya Karolinska Solna” (NKS) has been studied regarding the deformations during the construction phase. This was made by using field measurements. Meanwhile, a FEM analysis of the same design was made with the program PLAXIS, a program designed for geotechnical FEM simulations. This has been performed in order to compare deformations obtained by field measurements and simulations, respectively, for evaluating the advantages and disadvantages of simulation of deformation in a project like the one studied.The project at NKS has been studied at the construction site during the spring and summer of 2011. Previously made geotechnical investigations at the construction site were studied and analyzed. More specific investigations and studies were made in order to obtain appropriate soil and sheet pile parameters, making the simulation as real as possible in PLAXIS. This includes triaxial test, routine examination and probing methods of the soil, as well as producing sufficient accurate parameters by estimates and assumptions. The installation of inclinometers and brace force transducer for field measurements has been made to study the field conditions. The results were calculated and interpreted.In comparison, it was noticeable that the difference in result between the simulation and field measurements did not differ remarkably. The movements were relatively small in view of the soil’s character, friction soil, in which the deformations, as a result of sheet piling and excavation are usually not very large. A Sensitivity Analysis with respect to two of the parameters, friction angle and Young’s modulus were performed. It was concluded, in the light of the Sensitivity Analysis, that these parameters can be estimated, using relations with simple probing methods, without the result being markedly different in a simulation of a structure like the one studied.However, it was found that more carefully conducted geotechnical surveys, than those that were available before this study, is a prerequisite to assure a true FEM analysis. Today, it is very unusual, as in the studied case, that the industry does more thorough geotechnical investigations for sheet pile design. Therefore a numerical simulation of an object is often very difficult to carry out. In friction soil where the deformations are small, FEM simulation is also seen as superfluous if not a special risk due to small-scale deformation/settlements exists, which rarely is the case.
Place, publisher, year, edition, pages
2011. , 94 p.
Teknik, spont, FEM, PLAXIS, sättningar, deformationer, inklinometer, stagkraftsgivare
IdentifiersURN: urn:nbn:se:ltu:diva-44182Local ID: 1fa0618c-ce45-4f35-9f45-06cad913d8f6OAI: oai:DiVA.org:ltu-44182DiVA: diva2:1017457
Subject / course
Student thesis, at least 30 credits
Civil Engineering, master's level
Validerat; 20110830 (anonymous)2016-10-042016-10-04Bibliographically approved