Abstract: A deep excavation project was located in Guizhou red clay area. The new backfill and red clay deposits are at the backside of supporting soldiers. The depth of deep excavation is about 11.7 m and the double row pile support method were used. The existing theoretical analyses of the deformation do not meet the requirements of the project specifications. As a results, a panel of expert discussion was conducted, the review of the existing design parameters by the structural and geotechnical firms, review of the composition of the backfill material, degree of compaction and age of the backfill material have been performed. A new observational method was used in deep excavation construction. The construction monitoring program was implemented, and the monitored data was used the future construction excavation. Further, the ground anchor to be installed in between the double row piles was used as the emergency remediation approach if the excessive deformation was observed in the supporting structures. The construction monitoring data indicated that the deformation of the deep excavation supporting structure met the design required. The reliability of the new method has been verified and the results can be applied in the excavation support in similar projects.

Key words: Deep Excavation, Red Clay, Deformation Monitoring, Backfills, Double Row Piles