Analys av sättningar genom 3D-modellering av provbank på MC-förstärkt lera

Sammanfattning: The purpose of the thesis is to numerically and analytically predict settlements from a test embankment constructed on MC-reinforced clay in Täby Park. The thesis also provides a description of how the test embankment should be instrumented to enable comparison with the calculated settlements. The main objective is to compare the settlements in the piles versus the clay.The test embankment has not yet been constructed at the time of writing this report. The embankment will be built by Skanska AB and have a width of 15 m and a length of 25 m, measured at the crest of the embankment. The embankment has a slope of 2:1 and a height of 4 m. The MC-columns have a diameter of 800 mm and are spaced at 650 mm between the columns and 2.2 m between the rows. The expected service life of the test embankment is 30 years.The results from the numerical simulations show a total settlement of approximately 120 mm for the 4 m high test embankment. It was also observed that the columns are loaded beyond their failure limit, and no clear difference could be seen between deformations in the clay versus the columns. A 2 m high embankment was simulated to investigate the settlement behavior when the columns were not loaded beyond their failure load. In the case of the 2 m high test embankment, the numerical simulations showed a settlement of approximately 30 mm, which also showed relatively good agreement with the analytical calculations that were performed. A slight difference between the columns and the clay could be observed in this case.It is recommended to instrument the test embankment with settlement markers and settlement gauges to measure the settlements. A total of 8settlement markers will be installed, placed both on the columns and in the clay. Four settlement gauges will be installed, with two measuring settlements along the embankment in the clay and two measuring settlements along the embankment in the columns. Measurements of the embankment are recommended to be conducted daily during the first month after installation.Afterward, measurements can be conducted weekly for the remaining time of the first year. In the following year, measurements should be done on amonthly basis, and then semi-annually.Prior to the construction of the test embankment, a modification should be made to avoid loading the columns beyond their failure load. This can be achieved either by reducing the height of the embankment or by using denser spacing of the columns. Furthermore, it is recommended to conduct additional geotechnical measurements in the area and to manufacture test columns at the site. The test columns should also be subjected to long-term testing to investigate any potential stiffness development.