Deep mixing improvement of soft ground adjacent to a historic masonry wall: Performance and impacts on surroundings

Abstract

This paper presents a case study of deep mixing performed to improve soft ground adjacent to a historic masonry wall in an urban redevelopment site. A challenge of the site was to perform the redevelopment without impairing the masonry wall of historic importance. For the foundation of a retaining wall adjacent to the masonry wall, deep mixing was applied and its impacts on the masonry wall were monitored during the construction. Using small construction equipment customized to cramped conditions, 193 soil-cement columns were installed by deep mixing technique. Strength characteristics of the improved ground, vibration velocities with respect to the distance from the equipment, and displacements of the masonry wall throughout the construction were evaluated by laboratory tests and field measurements. The results indicate that not only the strength of ground was improved to meet the design strength but also the vibration levels and displacements induced by deep mixing were less than regulations. © 2012 American Society of Civil Engineers.