Numerical analysis of consolidation behavior of soil-bentonite backfill in a full-scale slurry trench cutoff wall test

The stress state of the SB backfill in a full-scale cutoff wall test during the construction and consolidation was simulated by a finite-element model. The applicability of the model was demonstrated by good agreements between modeled and field monitored earth pressures and pore pressure in the backfill. Based on the analyzed results, the backfill consolidation process can be described as a four-staged cycle of load transfer: (1) the effective stress of the backfill increases due to the dissipation of excess pore pressure caused by self-weight consolidation of the backfill; (2) the increased effective stress results in settlement of the backfill and an increase of sidewall friction between the backfill and the sidewall interface; (3) the increased sidewall friction results in the transfer of backfill weight to the sidewalls and a decrease of the consolidation stress on the backfill; and (4) the decreased consolidation stress attenuates the decrease of excess pore pressure, influencing the subsequent consolidation. The cycle from (1) to (4) continues until the consolidation is completed.