Proceedings - 13th International Workshop on Micropiles - 2017, Vancouver, BC, Canada, (ISM, DFI, ADSC)
Stabilization of the Nyköping’s riverbank with micropile-walls
Vazquez, A., Aronsson, S. and Marxmeier, N.
Along the Nyköping River (100 km south of Stockholm), the slope of the northern riverbank indicated a potential sliding failure – especially around the area called “Åkroken” which is planned to become a new residential area. The cross section of “Åkroken” shows a steep slope (~ 20%) with heavy surcharge loads on top due to the building plans. The geology consists of approx. 1 m upper filling material “rich” on archaeological findings from medieval times (12th century). Beneath the filling there is approx. 7-9 m silty-clayey layer over the bedrock. This slope is supported with masonry gravity walls founded into the river bed. However, these walls showed clear signs of instability since the wall was tilting towards the river. As a prevention measure, the city council cordoned off the area. ÅF Consult was committed to assess the stability of the slope and design safety measures to both be able to renovate the masonry walls and increase the factor of safety for the entire fringe. As a remediation measure a micropile-wall was recommended to prevent the effects of a landslide failure in the Nyköping River. The micro-pile wall’s main functions was to avoid further displacements during the renovation of the old masonry walls, and later on to work as a permanent structure. The micropilewall was designed for 100 years life-span according to Swedish Standards. Bored micropiles, Ruukki RD 170/12.5 mm, were installed c/c 1 m and filled with concrete. Tieback anchors, Ischebeck TITAN 73/53, were installed c/c 2.5 m with a 45 degrees inclination and embedded in rock. Numerical analysis (PLAXIS and Geostudio) were utilized to assess the slope stability and estimate the range of displacements during the construction of the micropile walls. Geotechnical investigations estimated the material properties for the calculations.
|article #2631; publication #1033 (ISM- 2017)|