Stabilization of Low-Level Waste Burial Trenches by Dynamic Compaction

摘要

As part of a low-level radioactive waste burial site stabilization and closure technology demonstration project, a group of five 14-year-old burial trenches in Oak Ridge National Laboratory (ORNL) Solid Waste Storage Area (SWSA) 6 was selected for testing trench compaction, grouting, and infiltration barrier design and performance. To obviate the chronic problem of trench subsidence and to provide foundation support for the infiltration barrier, the five trenches were dynamically compacted by the repeated dropping of a 3.6-Mg weight, with a 1.1 sq m base, onto each trench from a height of approximately 7 m. The five trenches were compacted to a maximum depth of 1.2 m, requiring an average of 5.5 drops/sq m of trench area, and the site was graded to facilitate surface runoff. Measurements of void reduction within the trenches averaged 77% and were calculated by a comparison of ground surface depression and measured water-accessible voids prior to compaction. Penetration tests were performed on trenches before and after compaction and on the surrounding undisturbed soil formation. The penetration resistance of the trenches was extremely low before compaction and was increased to a level equivalent to that of the undisturbed soil after compaction. Thus, dynamic compaction was found to be very effective in stabilizing burial trenches to the extent that no differential land surface settlement should be expected to compromise the foundation support of an infiltration barrier. 2 refs., 5 figs., 2 tabs.