In the heart of Bangladesh, researchers are shaking things up—literally—to better understand how underground structures behave during earthquakes. A recent study, led by Md. Foisal Haque from the Department of Civil Engineering at Bangladesh University of Engineering and Technology, has shed new light on the seismic performance of concrete tunnels, sand, and pile interactions. The findings, published in *Deep Underground Science and Engineering* (which translates to *Deep Underground Science and Engineering*), could have significant implications for the energy sector, particularly in regions prone to seismic activity.
The research team conducted a one-dimensional gravitational shake table test, subjecting a concrete tunnel-sand-pile interaction model to seismic excitations mimicking the Kobe and Loma Prieta earthquakes. “We applied a vertical load of 40 kg on each pile cap to simulate real-world conditions,” Haque explained. The results were then compared with previous numerical studies and 3D full-scale numerical analysis using the Mohr-Coulomb constitutive model of sand.
One of the key findings was that the lateral displacement of the tunnel was greater than the vertical displacement due to the transverse directional seismic excitation. “The minimum difference between lateral and vertical displacements was 31% for a relative density of 27% under the Loma Prieta earthquake,” Haque noted. This insight could be crucial for designing more resilient underground structures, particularly in the energy sector where tunnels and piles are often used for infrastructure and resource extraction.
The study also found that the ratio between the previous field data obtained through numerical study and the present study was 0.96 for vertical sand displacement, indicating a high level of consistency. “The variations of experimental and numerical results show a satisfactory level of alignment with the previously published work,” Haque added.
So, what does this mean for the future of underground construction and the energy sector? Haque suggests that this research could be advanced by considering various peak ground accelerations, tunnel-pile clearance, and geometric properties. “Understanding these interactions better will help us design more robust and safer underground structures, which is particularly important for the energy sector where infrastructure often needs to withstand significant seismic forces,” he said.
As the world continues to grapple with the challenges of climate change and the need for sustainable energy solutions, research like this is more important than ever. By improving our understanding of how underground structures behave during earthquakes, we can help ensure that the energy infrastructure of the future is both resilient and reliable.