ABSTRACT
When tunneling with Earth Pressure Balance (EPB) shield Tunnel Boring Ma-chines (TBMs), soil conditioning improves the physical properties of excavated soil through the application of various additives. This process transforms the excavated soil into a plastic-fluid state, yielding beneficial effects. Common additives include foam and polymers; however, con-ventional polymers pose environmental risks during production and decomposition. To address these concerns, this study investigated the feasibility of using xanthan gum for soil conditioning. Xanthan gum is an eco-friendly biopolymer derived from biological sources and is biodegradable. For this purpose, a slump test was conducted by varying the content of conventional polymer and xanthan gum in artificial sandy soil with a water content of 16%. Replacing the conventional polymer with an equivalent amount of xanthan gum resulted in similar slump values. Addition-ally, a laboratory pressurized vane shear test was conducted to quantitatively compare their rheo-logical properties. Under conditions producing similar slump values, the peak strength decreased remarkably as the xanthan gum content increased.
