Search Results (3)

The dynamic loads affecting earth-retaining structures may increase in seismically active regions. Therefore, studying the soil–structure interaction among the soil, shoring systems, and adjacent structures is crucial. However, there is limited research on this important topic. This study investigates the seismic performance of a deep braced excavation and a nearby 10-story building in sandy soil formation. The main focus of this study is the consideration of the influence of varying foundation depths of adjacent structures on the seismic response of the shoring system and the performance of the shoring system and adjacent structure under different earthquake records. PLAXIS 2D software (Version 22.02) was used to carry out the numerical analysis. Sandy soil was modeled using the Hardening Soil with small-strain stiffness model (HS-small). Back analysis of observation data extracted from a real case study of a deep braced excavation in the central district of Kaohsiung City, adjacent to the O₇ Station on the Orange Line of the Kaohsiung MRT system in Taiwan, was used to validate the numerical analysis. Beyond model validation, a parametric study was conducted to address the effect of the foundation level of the building adjacent to the excavation on both the seismic behavior of the shoring system and the structure itself, using the Loma-Prieta (1989) earthquake record. The parametric study was further extended to assess the responses of the shoring system and the adjacent structure under the influence of the earthquake records of Loma-Prieta (1989), Northridge (1994), and El-Centro (1940). The results show that the maximum lateral displacement of the diaphragm wall occurred at the top of the wall in all studied cases. The maximum dynamic bending moment in the retaining structure was more than three times the static one on average. In contrast, the dynamic shear force was more than 2.85 times the static one on average. In addition, the dynamic axial force of the first and second struts was 1.38 and 3.17 times the static forces, respectively. The results also reveal large differences in the behavior of the shoring system and the adjacent structure between the different earthquake records. Full article

The geological nature of the territory of the Republic of Cuba has favoured the formation of large and varied deposits of volcanic tuffs enriched by various species of zeolites. Today, new zeolite deposits continue to be discovered in the country. This work aims to present the results of a study carried out in an unexplored area that is located approximately 1.2 km east of the Loma Blanca deposit, outside the mining operation limits. To carry out this research and to establish a qualitative comparison between both sample populations, four samples were taken from the study area, and another four were taken from the Loma Blanca deposit. The characterisation of the samples was performed by XRD, SEM, and XRF. The pozzolan quality was determined by the pozzolanicity test (PT) and quality chemical analysis (QCA). Finally, a study of the mechanical strength (MST) was performed at 7, 28, and 90 days, using mortar specimens made with PC/ZT: 75–25% and PC/ZT: 70–30%, respectively. The results of the studies using XRD, SEM, and XRF indicated that both groups of samples had a similar complex mineralogical composition, consisting mainly of mordenite and clinoptilolite accompanied by secondary phases such as quartz and amorphous materials in the form of altered glass. The pozzolanicity test showed that both the samples from the study area and those from the Loma Blanca deposit behaved like typical pozzolans, which is a trend that can be seen in the high values of mechanical strength to compression up to 72 MPa for the PC/ZT: 75–25% formulation and 66 MPa for the PC/ZT: 70–30%. The results obtained establish that the zeolite varieties detected in the study area are similar to those of the Loma Blanca deposit, which could have a positive impact on the increase in current reserves, especially for manufacturing pozzolanic cements with properties that contribute to the preservation of the environment. Full article

The Atacama Desert at its margins harbors a unique biodiversity that is still very poorly known, especially in coastal fog oases spanning from Perú towards the Atacama coast. An outstanding species-rich fog oasis is the latitudinal fringe Paposo-Taltal, that is considered an iconic site of the Lomas formation. This contribution is the first to reveal the knowledge on arthropods of this emblematic coastal section. We used pitfall traps to study the taxonomic composition, richness, and abundance of terrestrial arthropods in 17 sample sites along a 100 km section of the coast between 24.5 and 25.5 southern latitude, in a variety of characteristic habitats. From a total of 9154 individuals, we were able to identify 173 arthropod species grouped into 118 genera and 57 families. The most diverse group were insects, with 146 species grouped in 97 genera and 43 families, while arachnids were represented by 27 species grouped into 21 genera and 14 families. Current conservation challenges on a global scale are driving the creation and evaluation of potential conservation sites in regions with few protected areas, such as the margins of the Atacama Desert. Better taxonomic, distributional, and population knowledge is urgently needed to perform concrete conservation actions in a biodiversity hotspot at a desert edge. Full article