Abstract: In highly permeable silty soils, cut-off curtain induced deep excavation supporting structure failures are frequently encountered under the complexity of geological conditions and underground buried objects. This paper presents a case history of jet-grouting formed cut-off wall failure in a deep excavation project in Suqian, Jiangsu Province. The detail information of subsurface conditions, adjacent existing buildings, and construction of the cut-off wall installations are presented. Factors that might result in the seepage failure and potential mitigation measures are also evaluated in the paper. Methods that were used in the seepage minimization are introduced in the paper. The site construction monitoring data verified that the cut-off wall seepage failure mitigation methods are effective.

Key words: building foundation deep excavation, cutoff curtain, factors cause seepage failure, jet grouting columns, mitigation measures