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Earthquake Vulnerability and the State-of-the-Art of Hybrid Structural Reinforcement and Soil Improvement Methods for NonEngineered Structures

2024-02-09T01:05:28Z

Earthquake Vulnerability and the State-of-the-Art of Hybrid Structural Reinforcement and Soil Improvement Methods for NonEngineered Structures Ortiz Palacio, Santiago; Ibáñez García, Sergio; López Ausín, Víctor; Porres Benito, José Ángel In the course of the last decades many efforts have been focused on the design of effective countermeasures to retrofit pre-existing engineered structures -including both buildings and civil constructions- to properly resist the effects of primary and secondary seismic failure induced mechanisms. On the other hand, due to several reasons which will be here summarized, non-engineered buildings (e.g.: unreinforced masonry structures, shack housing in developing countries, adobe dwellings, etc.) have not been so widely studied. As these structures are far from simple, they pose many interesting issues regarding earthquake vulnerability and the challenging tasks of either retrofitting their design or performing soil and foundation improvements in frequently difficult psycho-environmental settings. In this presentation, some of the most outstanding features of non-engineered buildings will be detailed. Also, a summary of some of the most effective approaches of hybrid structural and soil improvements will be discussed with some guidelines for future studies. Trabajo presentado en: 6th International Conference on Earthquake Geotechnical (6ICEGE) that was held on November 1-4, 2015, in Christchurch, New Zealand

Geology and Geomorphology of Azokh Caves

2024-02-09T01:05:27Z

Geology and Geomorphology of Azokh Caves Domínguez Alonso, Patricio; Aracil Ávila, Enrique; Porres Benito, José Ángel; Andrews, Peter; Lynch, Edward P.; Murray, John Azokh Cave is located in the Lesser Caucasus and is hosted in Mesozoic limestone. It comprises a series of karstic cavities, chambers and passageways that interconnect to form a larger cave network, the trend of which appears to have been influenced by fracture patterns in the bedrock. The geomorphology of the currently accessible areas of the cave is presented, with many of its speleological features described in detail for the first time. Electrical resistivity tomography is used to examine variation in thickness of sediments infilling the inner chambers of the cave. This information, coupled with data relating to the surface topography of the cave infill, sheds light on patterns of sediment deposition within the cave system. It remains unclear whether the cave formed from epigenic or hypogenic speleological processes (or a combination of the two). This question is further hampered by the presence of a large bat population in the interior of the cave, the guano deposits of which have modified the inner galleries.

Applying electrical resistivity tomography to the identification of endokarstic geometries in the Pleistocene Sites of the Sierra de Atapuerca (Burgos, Spain)

2024-02-08T01:05:33Z

Applying electrical resistivity tomography to the identification of endokarstic geometries in the Pleistocene Sites of the Sierra de Atapuerca (Burgos, Spain) Ortega, Ana Isabel; Benito Calvo, Alfonso; Porres Benito, José Ángel; Pérez González, Alfredo; Martín Merino, Miguel Ángel In this paper we have applied the electrical resistivity tomography (ERT) in order to prospect and to analyse the morphological and geological subsurface of the Torcas-Cueva Mayor endokarst system (Sierra de Atapuerca). These works are essential to establish the development of the sedimentary infills where the Early and Middle Pleistocene archaeo-palaeoanthropological sites of the Sierra de Atapuerca are located. The prospecting was based on the elaboration of 15 ERT sections, which were interpreted using topographic, archaeological, geological and geomorphological data. Through this procedure we have indentified the endokarst morphologies and the main lithological groups. The latter correspond to the Upper Cretaceous limestones and dolostones (> 1500 ohm m−1) and Neogene sediments and Quaternary valley infills (< 400 ohm m−1). The endokarst structures inside the Upper Cretaceous carbonates were related to empty cavities (> 1500 ohm m−1), passages filled with speleothems (400–1500 ohm m−1and with detrital materials (< 400 ohm m−1), such as the deposits of the Dolina, Elefante and Galería sites. The analysis of these subsurface structures shows that the karstic passages present a regular south–north development, starting with subsurface faults detected in the north margin of the main valley (Arlanzón River) and finishing along the Pico valley headwaters. These passages were cut off by the Pleistocene incision of the Sierra de Atapuerca minor valleys (e.g. Propiedad valley), forming entrances to caves that were occupied by hominids and fauna from Early Pleistocene times.

Geophysical and in situ testing applied to site characterisation for nonengineered structures in developing regions

2024-02-14T13:24:53Z

Geophysical and in situ testing applied to site characterisation for nonengineered structures in developing regions Ortiz Palacio, Santiago; Ibáñez García, Sergio; López Ausín, Víctor; Porres Benito, José Ángel Residential dwellings have been estimated to represent more than three quarters of the building stock around the globe, most of which are not believed to have been properly engineered (that is, designed by architects or engineers and constructed by skilful workers with adequate materials). Narrowing the scope to developing countries, over a 90 percent of the population is deemed to be living, working or studying in nonengineered buildings. In earthquake-prone regions, these weak structures can become deathtraps for their occupants, forlornly adding to the casualty lists of recent and past seismic events. Thus, improving seismic resilience for vernacular housing has increasingly become a main theme for researchers. Also, other geotechnical issues, such as subsidences, slope instabilities, excessive settlement on soft soils, groundwater, inadequate designs, etc., are responsible for substantial risk of structural damages, ranging from small structural pathologies to major disasters. One of the keys to develop new safe and efficient foundation designs, or to retrofit existing ones, is to make available portable and low-budget ground probing techniques. This document will describe some of the most feasible in situ devices available, as well as discuss how seismic and electric methods can be used as portable and powerful tools to characterise both the strength and the stiffness of soils thanks to recent developments in stablishing the relationship between geophysical results and traditional geotechnical parameters (such as the SPT, the angle of internal friction, shear strength, etc.), with the help of statistical methods and dimensional analysis techniques. Trabajo presentado para el congreso Geotechnical and Geophysical Site Characterisation 5 de 2016