Liquefaction of mine waste rock and its mitigation using vertical drains in centrifuge model tests

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In this study, dynamic centrifuge tests were performed to evaluate the performance of vertical drains in mitigating liquefaction of mine waste rock. Testing was conducted at the centrifuge acceleration of 50 g to simulate a 8-m unform level profile of loose waste rock representing by a saturated poorly-graded sand with gravels and fines. Each model was subjected to a sinusoidal shaking motion with peak acceleration of 0.4 g in prototype scale for a total 40 number of cycles. Results were analyzed by comparing results of the baseline test (without drains) with the model test with the vertical drains. The study examined a pattern of 18 vertical drains having a prototype diameter of 150 mm installed to a depth of 4 m with a spacing of approximately 1 m. Results show that the top half of the model without drains liquefied based on the development of pore water pressure. For the model with drains, excess pore pressure in the top half of the model reduced by approximately 15-20% and liquefaction did not occur. There was no difference in the excess pore pressure at the deeper depths below the drains for both models. Upward dissipation of pore water was observed at deeper depths for both models due to the relatively high permeability of the soil. Surface settlement occurred as the model was densified in both tests. However, the use of drains to reduce soil settlement was not clearly observed as it is likely due to the presence of gravels. 

9th International Congress on Environmental Geotechnics (ICEG2023)

Resource Mining and Extraction