Static Analysis of a Masonry Arched and Buttressed Retaining Wall

Abstract

The wall of Casa Salvans is a masonry arched and buttressed retaining wall which was built in 1909 and located in Terrassa, Catalonia. It contains a series of 11 arches of unique shapes, dimensions and inclinations that are supported on buttresses. Despite being a common retaining wall typology, it can be very challenging to assess the stability of such structures given the variability of their geometry. As such, a systematic methodology for the stability assessment of such walls was developed and applied to the case of the wall of Casa Salvans. Self-produced photogrammetry survey enabled creating accurate three-dimensional models of the front of the wall that were later combined with available information from a topographic survey to build cross sections of the wall for analysis. Modern retaining wall design principles evaluating the stability against overturning and sliding were used to assess the condition of the wall. As a consequence of the uncertainties related to the soil parameters and buried elements of the wall, the stability factors could not comply with modern design criterion. Some parametric analyses were carried out on the shear strength parameters of the backfill, revealing that slight increases in the soil internal friction and wall friction angles enhance the stability factors significantly. Since reasonable soil internal and wall friction angles justifying the stability of the wall were obtained, carrying out a geotechnical survey to determine the actual values was recommended. The in-plane stability of the arches was also verified according to the Lower Bound Theorem by locating a thrust line that fits within all the boundaries despite very conservative geometric assumptions.

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