To safeguard historic centers with masonry buildings in medium-high seismic areas, the local seismic response (LSR) should be used. These portions of the urban areas are commonly characterized by complex subsurface features (i.e., underground cavities, buried anthropic structures, and archeological remains) that could be responsible for unexpected amplifications at period intervals similar to the building's ones. In this study, San Giustino's Square (Chieti, Italy) was considered due to the differentiated damage caused by the 2009 L'Aquila earthquake mainshock (6 April 2009 at 3:32 CEST, 6.3 Mw). Out of the eight buildings overlooking the square, the structure that suffered the heaviest damage was the Justice Palace. Two-dimensional finite element analyses have been carried out in San Giustino's square to predict the LSR induced by the seismic shear wave propagation. The influence of the Chieti hill, the anthropogenic shallow soil deposit, and the manmade cavity were investigated. The results outlined that the amplifications of the seismic shaking peaked between 0.2 and 0.4 s. The crest showed amplifications over a wide period range of 0.1-0.8 s with an amplification factor (FA) equal to 2. Throughout the square, FA = 2.0-2.4 was predicted due to the cavities and the filled soil thickness. The large amplified period range is considered responsible for the Justice Court damage.

Porous materials and structures, such as subterranean fire ant nests, are abundant in nature. It is hypothesized that these structures likely have evolved biological adaptations that enhance their collapse resistance. This research aims to elucidate the collapse-resistant mechanisms of pore geometries in fire ant nests. Finite Element Models of ant nests in soil were generated using X-ray CT imaging of aluminum castings of ant nests. Representative volume elements of the ant nests, representing porous structures at various depths, were analyzed under confined compression. This work on investigating fire ant (sp. Solenopsis Invicta) nests found them to be hierarchical and graded at various depths that affect how they resist loads and collapse. The top portion acts as a protective shield by distributing damage and absorbing energy. In contrast, the lower chambers localize stress, contributing to damage tolerance. This research provides evidence to suggest that ant nests have developed properties that allow them to resist collapse. These findings could inform the design of lightweight and durable cellular structures in various engineering fields.

Cavities behind the concrete lining of a shield tunnel may result in apparent damage or even collapse of the tunnel during its operation. It is necessary to predict the damage modes of a shield tunnel with cavities, and accordingly reinforce vulnerable areas of the tunnel. This paper investigates the damage modes of shield-tunnel models with cavities at different locations and sizes behind the concrete lining. The tunnel models used in the test are created using a 3D printing technique, with an aim of simulating the joints between segments. To consider the stratum-structure interaction, the tunnel models are created with grout-layers prefabricated between lining and soil. The 3D point cloud technique is then applied to observe the damage modes of the tunnel linings. The safety status of the shield tunnel is evaluated during the loading process, and categorized into safe, dangerous, and failure stages. Experimental results show that the damage modes of the shield tunnel with cavities contain concrete crack, concrete spalling, segment misalignment, and lining crush. Cavities at the tunnel crown and shoulder impose a substantial impact on the lining structure. Cracks propagating across three or more segments result in mutual compression between segments, forming a crack mesh, and consequently leading to concrete spalling. The tunnel lining undergoes a failure mode of segment misalignment when the cavity angle (size) is greater than 45 degrees. As the volume of the cavity increases, the tunnel lining transitions to a failure mode of lining crush. The results in this study will facilitate the proactive reinforcement of the tunnel by predicting damage modes induced by cavities, ensuring its safe operation to a certain extent.