Abstract:
Ground Improvement as an Enabling Technology for Deep Excavation Support: Lessons from Practice
Deep excavation in urban environments and challenging geotechnical conditions increasingly requires the integration of ground improvement techniques to ensure safe and effective construction. This presentation examines the practical application of ground improvement methods — including jet grouting, deep soil mixing, and artificial ground freezing — as enabling technologies for support of excavation (SOE) systems across a series of demanding infrastructure projects. Topics addressed include bathtub construction approaches using soldier pile walls with attapulgite clay/cement bentonite (AP/CB) lagging and jet grout base plugs for groundwater cutoff and buoyancy control in high-chloride groundwater environments, transient thermal analysis for ground freezing design supporting TBM tunneling in dense urban settings, and the deployment of jet grout columns below the bottom of excavation to mitigate heave in large-footprint, soft clay excavations. Each case study highlights the critical interface between SOE design and ground improvement selection, addressing challenges related to groundwater management, soil stability, deformation control, and constructability in constrained urban sites. The presentation offers practical insights for engineers involved in the design and construction of excavation support and ground improvement systems for complex underground infrastructure projects.