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The progressive development of slope failure which is a consequence of strain softening characteristics of soil is modelled within a probabilistic framework. The peak and residual shear strength parameters of a cohesive soil are treated as one-dimensional random fields. The overall failure or sliding probability is a function of a series of probabilities and conditional probabilities associated with the events of failure of segments of any slip surface within the slope. The influence of the mode or path of failure progression on the overall failure probability is investigated for an arbitrary slip surface and for a conventional critical slip surface. The influence of initial shear stress distribution along the slip surface is discussed. The number of assumed segments of a slip surface has a considerable influence on the probability of progressive failure. Failure initiated from a segment with the lowest reliability index leads to the highest probability of failure for the slope. Cet article décrit un modéle élaboré sous l'aspect de probabilitié pour le développement d'une rupture de talus résultant des caractéristiques de déformation–ramollissement du sol. Les paramétres de pic et résiduels de la résistance au cisaillement d'un sol cohérent sont considérés comme des champs unidimeusionnels produits au hasard. La probabilité totale de la rupture ou du glissement est une fonction d'une série de probabilités et de probabilités conditionnelles associées à la rupture des segments d'une surface de glissement quelconque à l'intérieur du talus. On examine pour une surface de glissement arbitraire aussi bien que pour une surface de glissement critique conventionnel l'influence exercée par le mode ou le chemin de progression de la rupture sur la probabilité totale de rupture. L'article discute I'influence exercée par la distribution initiale de la contrainte de cisaillement. Le nombre de segments supposés d'une surface de glissement exerce une influence considérable sur la probabilité de la rupture progressive. La rupture commencant à partir d'un segment ayant I'indice le plus bas de fiahilité conduit à la probabilité maximale de rupture pour le talus.

Indonesia has followed development of new seismic design criteria in the new seismic building codes, from hazard-based in the former SNI-03-1726-2002 to the current risk-based SNI-1726-2012. The major changes in SNI-1726-2012 are using Risk-Targeted Maximum Considered Earthquake (MCER) Spectral Response Acceleration maps. Five years later (2017), the seismic hazard maps have been updated adopting the most recent data and current state of knowledge in probabilistic and deterministic seismic hazard assessment methodologies. To establish the New 2019 Risk Targeted Ground Motion (RTGM) of spectral acceleration (Ss and S1), and risk coefficients (CRS and CR1), for both short (T=0.2s) and 1-second (T=1s) periods, respectively have been developed based on the 2017 Indonesian hazard maps. The RTGM was calculated as the spectral value resulting in 1% probability of building collapse in 50 years through numerical integration of hazard curves and structural capacity. The log-normal standard deviation (?) of the structural capacity envelope has been revised from 0.70 to 0.65. This paper presents the new resulted RTGM maps. Furthermore, the paper also presents revision of seismic amplification factors for 0, 0.2, and 1 second periods (FPGA, Fa, and, Fv) to generate ground surface maximum and design spectra associated with the siteclassifications.

None of numerous previous methods for predicting pile capacity is known how accurate any of them are when compared with the actual ultimate capacity of piles tested to failure. The author's of the present paper have conducted such an analysis, based on 130 data sets of field loading tests. Out of these 130 data sets, only 44 could be analysed, of which 15 were conducted until the piles actually reached failure. The pile prediction methods used were: Brinch Hansen's method (1963), Chin's method (1970), Decourt's Extrapolation Method (1999), Mazurkiewicz's method (1972), Van der Veen's method (1953), and the Quadratic Hyperbolic Method proposed by Lastiasih, et al. (2012). It was obtained that all the above methods were sufficiently reliable when applied to data from pile loading tests that loaded to reach failure. However, when applied to data from pile loading tests that loaded without reaching failure, the methods that yielded lower values for correction factor N are more recommended. Finally, the empirical method of Reese and O'Neill (1988) was found to be reliable enough to be used to estimate the Q ult of a pile foundation based on soil data only.

A probability based model of block failure capacity of pile foundation in clay soil under axial load is developed. The model was based on the first order second moment method. Instead of using point variability, the soil inherent variability is modelled as random field model. Based on this model, a reliability based factor of safety for designing pile group foundation, taking into account bock failure mechanism, is proposed. Furthermore, using simplified lognormal model, the relationship between the factor of safety used in design practice and target reliability may be derived explicitly.