Performance of a single-propped wall during excavation and during freezing of the retained soil

A single-propped soldier-pile-tremie-concrete wall was constructed as part of the excavation support system for a tunnel jacking project. This wall supported a 14.3-m-high cut with a significant unbraced height (13.4 m) above the excavation subgrade. A limited area of the excavation subgrade next to the wall was jet grouted to provide stability against base heave. The jet grout also served as a "brace" for the wall below subgrade. The wall and prop were designed to support lateral loads during excavation as well as during ground freezing behind the wall. A ground freezing operation was implemented and carefully controlled to prevent wall yielding. Its success was facilitated by monitoring of wall movements, by drilling relief holes adjacent to the wall to reduce lateral heave pressures due to the soil freezing operation, and by limiting the exposure time of the wall to frost expansion. Measured wall behavior during excavation and during ground freezing is compared to those from finite element analysis for this very unique case history. Published by Elsevier Science Ltd.