Influence of Execution Speed on Displacements of Soil-Nailed Structures with Vertical Face in Urban Areas

Abstract

This paper presents the study of the execution speed influence on displacements of soil-nailed structures with a vertical face in urban areas, intended as the basements of buildings. Fifteen structures in the Metropolitan Region of São Paulo, Brazil, were evaluated. The main objective was to demonstrate the evolution of the construction technique, making its application possible in conditions considered by the technical community to be unfeasible due to the inevitable resulting displacements. The studied structures ranged from 6.8 to 22.7 m high. Soil-nailed walls were instrumented with displacement gauges (deflectometers) positioned near the top, which monitored the structures’ horizontal displacements. The execution time of each work was evaluated in terms of the sectoral excavation advancement, which was 3, 4, or 5 days, as well as the production in square meters per day. The results showed works that were less displaceable than the estimates proposed in the literature. The impact of execution speed also was evidenced, showing that the opening interval of new work fronts resulted in significant differences, with displacements ranging from 20 to 23 mm, from 10 to 15 mm, and from 0 to 6 mm, respectively. Two equations proposed to predict horizontal displacement based on the retaining structure height and daily work productivity are presented. The study can enable works that may be considered impractical if analyzed from the displacement premises of the literature; moreover, this study disseminates design and execution standards to obtain less-displaceable works.