Centrifugal and Numerical Investigation of Surface Fault Rupture Hazard Mitigation for Shallow Foundations Using Micro-Piles

Surface fault rupturing mostly contributes to either large-scale destruction or minor damage of the constructions and the infrastructures which are built across fault zones. Among the numerous mitigation strategies which have been suggested, a novel approach refers to implementing expanded polystyrene sheets (EPS) wall to deviate the fault rupture. However, the shallow foundations which are protected by EPS walls still rotate in some particular positions toward the fault rupture. This study investigates the probability of deviating the reverse fault rupture by installing a strong inclined wall (SIW) beneath the surface foundation both physically and numerically. Due to the effectiveness of adopting the mentioned method, a further three-dimensional (3D) finite-element (FE) modeling is conducted, employing the validated numerical model to divide the SIW into a row of strong inclined micro-piles (SIMPs). The installation of SIMPs in both a convenient and environmentally friendly strategy was carried out and the pivotal parameters of designing such micro-piles including their diameter, the angle of installation, and the optimal distance between each two-consecutive implemented micro-piles were investigated in a parametric study. The results indicate that executing a well-designed row of micro-piles with the proper angle of installation can protect a surface foundation against a reverse fault rupture.

The changing strength of carbonate silt: parallel penetrometer and foundation tests with cyclic loading and reconsolidation periods

This paper describes a centrifuge study using novel penetrometer tests (T-bar and piezoball) and model foundation tests to explore through-life changes in the strength of a reconstituted natural carbonate silt. The test procedures include episodic cyclic loading, which involves intervals of pore pressure dissipation between cyclic packets. These loads and the associated remoulding and reconsolidation cause significant changes in the soil strength and foundation capacity. Soil strength changes from penetrometer tests differed by a factor of 15 from the fully remoulded strength to a limiting upper value after long-term cyclic loading and reconsolidation. For the model foundation tests, the foundation capacity of a surface foundation and a deep-embedded plate were studied. The soil strength interpreted from the measured foundation capacity varied by a factor of up to three due to episodes of loading and consolidation, with an associated order of magnitude increase in the coefficient of consolidation. The results show a remarkable rise in soil strength over the loading events and provide a potential link between changes in soil strength observed in penetrometer tests and the capacity of foundations, allowing the effects of cyclic loading and consolidation to be predicted.

Uso del georradar para la identificación y definición geométrica de estructuras de cimentación en edificaciones existentes = Use of georadar for the identification and geometric definition of foundation structures in existing buildings

Resumen Se presenta en este trabajo un resumen de los resultados obtenidos en los últimos años en la caracterización de distintas estructuras de cimentación mediante georradar, metodología no invasiva que con la combinación de antenas de distintas frecuencias permite conocer el tipo de cimentación superficial (zapata, losa), sus dimensiones en planta y en profundidad, así como los niveles de armadura interna existentes. En el caso de las cimentaciones profundas su aplicabilidad es más limitada, pero en determinadas condiciones, puede suministrar los parámetros geométricos principales. La información así obtenida permite abordar los proyectos de rehabilitación con una mayor seguridad y economía de recursos, al permitir conocer las geometrías de los elementos de cimentación y su variación, sin necesidad de acceder al subsuelo de forma directa o al menos para reducir la caracterización directa o dotar a dichos resultados de representatividadAbstractThis paper presents a summary of the results obtained in recent years in the characterization of different foundation structures by means of georadar, a non-invasive methodology that with the combination of antennas of different frequencies allows to know the type of surface foundation (zapata, slab) , its dimensions in plan and in depth, as well as the existing internal reinforcement levels. In the case of deep foundations, its applicability is more limited, but under certain conditions, it can supply the main geometric parameters. The information thus obtained allows us to address the rehabilitation projects with greater security and economy of resources, by allowing to know the geometries of the foundation elements and their variation, without the need to access the subsoil directly or at least to reduce the direct characterization or endowing said results with representativeness.