In the heart of Beijing, researchers are shaking things up—literally—to uncover how underground structures fare during earthquakes, especially in liquefiable sites. A team led by Zihong Zhang from the China Academy of Railway Sciences and Guanyu Yan from the Beijing University of Technology has conducted groundbreaking centrifuge shaking table tests, offering critical insights that could reshape how we design and build underground infrastructure, particularly in the energy sector.
The study, published in *Yantu gongcheng xuebao* (translated to *Chinese Journal of Geotechnical Engineering*), focuses on the seismic responses of underground structures in liquefiable soil conditions. Liquefaction, a phenomenon where saturated soil loses strength and stiffness during earthquakes, poses significant risks to infrastructure. The researchers aimed to understand how this process affects underground structures, such as those used in energy storage, transportation, and utilities.
Using centrifuge shaking table tests, the team simulated various earthquake scenarios to observe the structural responses. “The peak total strain responses of the sidewalls and plates of the model structures remained within the elastic range under all four loading conditions,” explained Zhang. This finding suggests that underground structures designed according to existing codes can withstand significant seismic events without severe damage. However, the strains on the center column just exceeded the elastic strain limit of concrete under large earthquakes, indicating a low level of damage but still within acceptable limits.
One of the most compelling discoveries was the attenuation of inter-story drifts in liquefiable sites. The researchers found that these drifts were reduced by 63% to 76% compared to those in non-liquefiable sites at the structural equivalent height. This means that even though liquefaction can cause larger horizontal displacements, the reduction in soil-structure stiffness ratio helps prevent excessive inter-story drift and serious damage.
The study also highlighted the importance of considering the most unfavorable conditions when applying the Pushover analysis method to underground structures in liquefiable sites. The researchers suggested that the soil modulus can be discounted to 3% of the initial modulus for accurate calculations.
The implications of this research are vast, particularly for the energy sector. Underground structures are crucial for energy storage, transportation, and distribution. Ensuring their seismic resilience is paramount for maintaining operational continuity and safety. “Our findings provide a robust framework for designing underground structures that can withstand seismic events, even in liquefiable soil conditions,” said Yan. This could lead to more reliable and safer energy infrastructure, reducing the risk of disruptions and enhancing overall system resilience.
As the energy sector continues to expand and diversify, the need for resilient underground infrastructure becomes increasingly critical. This research offers a valuable tool for engineers and planners, helping them make informed decisions that balance safety, cost, and performance. By integrating these findings into future projects, the industry can move toward a more secure and sustainable energy landscape.
In the quest for safer and more resilient infrastructure, this study marks a significant step forward. As the world grapples with the challenges of climate change and increasing seismic activity, the insights gained from this research will be invaluable in shaping the future of underground construction.