Estimación de desplazamiento admisibles para determinar el coeficiente K, en análisis pseudoestático de estabilidad de taludes de corte

Abstract

Se aplican procedimientos simplificados que estiman valores de desplazamientos sísmicos admisibles, involucrando la variación de características geométricas, altura e inclinación, aceleración crítica ky y parámetros de resistencia para diferentes modelos teóricos de taludes de corte así como la influencia del entorno sismogénico y espectro sísmico para las diferentes zonas de amenaza sísmica de acuerdo con el Mapa de Zonificación de Amenaza Sísmica del Servicio Geológico Colombiano 2020, para determinar el coeficiente de aceleración horizontal k de un análisis de estabilidad pseudoestático alcanzando factores de seguridad FS ≥ 1,0. La estimación de desplazamientos sísmicos admisibles para diferentes escenarios de diseño se realiza según lo propuesto en Bray et al, 2018 y Bray y Macedo, 2019; con la implementación de este procedimiento se logra generar un soporte técnico para la escogencia de un coeficiente de aceleración horizontal k, con el cual se reduce el Am para emplear en un análisis de estabilidad pseudoestático según lo establecido en la AIS, 2010 ,por lo que, al involucrar índice de desplazamiento admisible en el cálculo del k, este se reduce de manera óptima tal que aún se garantizan los factores de seguridad mínimos y envuelve el entorno sismológico en él está inmerso el talud de análisis.

It is important to know, for the analysis site, which is the seismogenic source that contributes the greatest seismic hazard to the total exceedance probability curve identified for each return period. For those areas that do not have seismic microzonation studies, this information can be found in the Seismic Hazard Study for Colombia 2009; given that the same site of interest within the radius of coverage of the analysis may be affected by different seismogenic sources, but it is the one that contributes most to the seismic hazard that dominates the analysis of seismic displacements generated by earthquakes associated with different seismogenic sources. The estimated range of expected seismic displacement for a slope are not precise estimates since to be accurate additional knowledge is required by performing advanced analyses, however, by having an idea of the expected range the proposed procedure is useful and can also provide reasonable estimates for cases where advanced analyses are not justified. It is emphasized that the values obtained as allowable seismic displacements should be taken as indices of the slope behavior after the occurrence of an earthquake generated by different seismogenic sources. Therefore, for the implementation of the procedures for both the estimation of displacements and the horizontal acceleration coefficient, the analysis criteria, the premises exposed throughout the document and the limitations that are intrinsically in each formulation must be taken into account. However, it is specified that the results obtained should not be generalized, neither for the same geometric characteristics, shear strength or seismological environment, since each slope is independent and the values of displacement and horizontal acceleration coefficient are intrinsically linked to the specific and local conditions of the slope under study. In order to validate the procedures used in this analytical thesis, but in the context of the seismological and geological environment of Colombia, monitoring and instrumentation plans should be implemented in both natural and shear slopes in order to know which would be the admissible seismic displacements generated by each seismogenic source.