The classical problem of the rocking response of freestanding slender blocks to earthquake ground shaking is revisited in the framework of slope stability. Toppling of rock blocks, completely detached from the cliff and logged upon an horizontal plane, triggered by dynamic motions on rigid ground is investigated by means of a two-dimensional mechanical model implemented using a state space formulation. The equations governing rocking problem must take into account for the energy loss at every impact; during the rocking motion, it is assumed that the rotation continues smoothly from one edge of the base of the block to the other and the coef- ficient of friction is large enough to prevent sliding. Validation of the model has been conducted by comparing literature results for idealized simple cyclic pulses as excitation. A sample of 62 recorded earthquake motions on rock soil (from US, Europe and Asia) has been used as input seismic excitation. The records cover a wide range of key characteristics in order to evaluate the effects on toppling of various parameters such as PGA, PGV, Arias Intensity, energy flux, frequency content. Results show as the pseudo-static criterion, based on the peak ground acceleration, is enable to capture overturning potential but only indicates the uplift condition. Whereas pseudo-static approach is widespread in design codes, reductive coefficients are a novelty suggestion for toppling phenomena to account the beneficial effect coming from the dynamic results. Furthermore, it is found that the toppling of smaller blocks is more sensitive to the peak ground acceleration, whereas the toppling of larger blocks mostly depends on the ground velocity.
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AUTORI: Maiorano R. S. M., Adinolfi M., Aversa S.
RIG ANNO:2014 NUMERO:2
Numero di pagine: 89
Articolo completo: https://associazionegeotecnica.it/wp-content/uploads/2018/01/2_2015_087maiorano.pdf