Experiences in the design and construction of true abutments in areas of high seismicity

Abstract

The use of mechanically stabilized soil retaining structures has been booming in recent years in Central America, especially in road structures. One of less used uses and more specialized is as a true abutment in bridges, where geometry and loads must be analysed with special attention. During the last 20 years we have participated in the design and construction of 8 true abutment structures with segmented block facades and extensible reinforcements in Guatemala and El Salvador, areas of high seismicity. These abutments work as a gravity wall, where the geosynthetic reinforcement creates together with the fill soil a monolithic block. The integrity of these is guaranteed by the internal analysis of the structure, but due to the high loads to which it is subjected and high seismicity, it is necessary to perform composite and global stability analyses. Within the internal analysis, the tensile strength, pull-out strength and slip resistance of the geogrid are verified, as well as the strength of the geogrid-block connection in the case of using segmental blocks as a facade. This publication seeks to share the experiences and difficulties in the design and construction of this type of structures under high seismic conditions, based on these 8 projects.