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排序方式: 共有189条查询结果,搜索用时 15 毫秒
1.
Salvatore Erminio Modoni Giuseppe Spagnoli Giovanni Arciero Michela Mascolo Maria Cristina Ochmański Maciej 《Acta Geotechnica》2022,17(11):5073-5087
Acta Geotechnica - Plasticity of clays makes Deep Soil Mixing (DSM) problematic due to the tendency of the material to congest the rotating blades, reduce mixing efficiency and remain... 相似文献
2.
A performance-based adaptive methodology for the seismic evaluation of multi-span simply supported deck bridges 总被引:1,自引:1,他引:0
Donatello Cardone Giuseppe Perrone Salvatore Sofia 《Bulletin of Earthquake Engineering》2011,9(5):1463-1498
A performance-based adaptive methodology for the seismic assessment of highway bridges is proposed. The proposed methodology
is based on an Inverse (I), Adaptive (A) application of the Capacity Spectrum Method (CSM), with the capacity curve of the
bridge derived through a Displacement-based Adaptive Pushover (DAP) analysis. For this reason, the acronym IACSM is used to
identify the proposed methodology. A number of Performance Levels (PLs), for which the seismic vulnerability and seismic risk
of the bridge shall be evaluated, are identified. Each PL is associated to a number of Damage States (DSs) of the critical
members of the bridge (piers, abutments, joints and bearing devices). The IACSM provides the earthquake intensity level (PGA)
corresponding to the attainment of the selected DSs, using over-damped elastic response spectra as demand curves. The seismic
vulnerability of the bridge is described by means of fragility curves, derived based on the PGA values associated to each
DS. The seismic risk of the bridge is evaluated as convolution integral of the product between the fragility curves and the
seismic hazard curve of the bridge site. In this paper, the key aspects and basic assumptions of the proposed methodology
are presented first. The IACSM is then applied to nine existing simply supported deck bridges, characterized by different
types of piers and bearing devices. Finally, the IACSM predictions are compared with the results of nonlinear response time-history
analysis, carried out using a set of seven ground motions scaled to the expected PGA values. 相似文献
3.
Flood-prone areas assessment using linear binary classifiers based on flood maps obtained from 1D and 2D hydraulic models 总被引:3,自引:0,他引:3
4.
5.
Laboratory experiments on simulated faults in rocks clearly show the temperature dependence of dynamic rock friction. Since rocks surrounding faults are permeable, we have developed a numerical method to describe the thermo-mechanical evolution of the pre-seismic sliding phase which takes into account both the rate-, state- and temperature-dependent friction law and the heat advection term in the energy equation. We consider a laminar fluid motion perpendicular to a vertical fault plane and assume that fluids move away from the fault plane. A semi-analytical temperature solution which accounts for the variability of slip velocity and stress on the fault has been found. This solution has been generalized to the case of a time varying fluid velocity and then was used to include the thermal pressurization effect. After discretizing the temperature solution, the evolution of the system is obtained by the solution of a system of first order differential equations which allows us to determine the evolution of slip, slip rate, friction coefficient, effective normal stress, temperature and fluid velocity. The numerical solutions are found using a Runge-Kutta method with an adaptative stepsize control in time. When the thermal pressurization effects can be neglected, the heat advection effect gives rise to a delay, with respect to the purely conductive case, of the earthquake occurrence time. This delay increases with increasing permeability H of the system. When the thermal pressurization effects are taken into account the situation is opposite, i.e. the onset of instability tends to precede that of the purely conductive case. The advance in the time of occurrence of instability increases with increasing coefficient of thermal pressurization. In the small permeability range (H ≤ 10?18 m2), the seismic moment and nucleation length of the pre-seismic phase are significantly smaller than those predicted by the purely conductive model. 相似文献
6.
This article focuses on the Montello thrust system in the Eastern Southern Alps as a potential seismogenic source. This system is of particular interest because of its lack of historical seismicity. Nevertheless, the system is undergoing active deformation. We developed a finite‐element model using visco‐elasto‐plastic rheology. The free parameters of the model (essentially, the locking status of the three thrusts included in the study), were constrained by matching the observed horizontal GPS and vertical levelling data. We show that the amount of interseismic fault locking, and thus the seismic potential, is not necessarily associated with the fastest‐slipping faults. More specifically, the locked Bassano thrust has a greater seismic potential than the freely slipping Montello thrust. The findings suggest that faults with subtle evidence of Quaternary activity should be carefully considered when creating seismic hazard maps. 相似文献
7.
8.
Aurélien van Welden Christian Beck Jean-Louis Reyss Salvatore Bushati Rexhep Koci François Jouanne Jean-Louis Mugnier 《Journal of Paleolimnology》2008,40(2):619-633
Lake Shkodra (northern Albania, southern Montenegro) is a large (45 km length, 15 km width) and shallow (5 m mean depth) lake,
developed on a mainly karstic carbonate substratum. Its recent sedimentary fill (mixed calcareous/siliciclastic clayey silts)
was analysed through short gravity cores representing five centuries of environmental archive. A combination of high resolution
texture analysis (particle size), magnetic susceptibility, carbon content, and radionuclide activity profiles (210Pb, 137Cs, 241Am) permitted us to detect and date environmental changes, such as the Little Ice Age and the 1962–1963 catastrophic floods.
Anthropogenic influences on the watershed, such as damming of the Drin River in the late 1970s, also appear to be recorded.
Impacts of known strong earthquakes (1905, 1979), however, could not be clearly detected in the sediment record. The potential
of the Shkodra lacustrine archive for paleoseismic investigations on long time intervals (such as Holocene) is discussed.
This paper is a preliminary contribution to Shkodra Lake’s Holocene paleolimnology. 相似文献
9.
This paper investigates the dynamic behavior and the seismic effectiveness of a non‐conventional Tuned Mass Damper (TMD) with large mass ratio. Compared with conventional TMD, the device mass is increased up to be comparable with the mass of the structure to be protected, aiming at a better control performance. In order to avoid the introduction of an excessive additional weight, masses already present on the structure are converted into tuned masses, retaining structural or architectural functions beyond the mere control function. A reduced order model is introduced for design purposes and the optimal design of a large mass ratio TMD for seismic applications is then formulated. The design method is specifically developed to implement High‐Damping Rubber Bearings (HDRB) to connect the device mass to the main structure, taking advantage of combining stiffness and noticeable damping characteristics. Ground acceleration is modeled as a Gaussian random process with white noise power spectral density. A numerical searching technique is used to obtain the optimal design parameter, the frequency ratio alpha, which minimizes the root‐mean‐square displacement response of the main structure. The study finally comprises shaking table tests on a 1:5 scale model under a wide selection of accelerograms, both artificial and natural, to assess the seismic effectiveness of the proposed large mass ratio TMD. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
10.
Andrew Harris Salvatore Alparone Alessandro Bonforte Jonathan Dehn Salvatore Gambino Luigi Lodato Letizia Spampinato 《Bulletin of Volcanology》2012,74(6):1293-1311
Between 1994 and 2010, we completed 16 thermal surveys of Vulcano’s Fossa fumarole field (Aeolian Islands, Italy). In each survey, between 400 and 1,200 vent temperatures were collected using a thermal infrared thermometer from distances of ~1?m. The results show a general decrease in average vent temperature during 1994–2003, with the average for the entire field falling from ~220°C in 1994 to ~150°C by 2003. However, between 2004 and 2010, we witnessed heating, with the average increasing to ~190°C by 2010. Alongside these annual-scale field-wide trends, we record a spatial re-organisation of the fumarole field, characterised by shut down of vent zones towards the crater floor, matched by rejuvenation of zones located towards the crater rim. Heating may be expected to be associated with deflation because increased amounts of vaporisation will remove volume from the hydrothermal system Gambino and Guglielmino (J Geophys Res 113:B07402, 2008). However, over the 2004–2010 heating period, no ground deformation was observed. Instead, the number of seismic events increased from a typical rate of 37 events per month during 1994–2000 to 195 events per month during 2004–2010. As part of this increase, we noticed a much greater number of high-frequency events associated with rock fracturing. We thus suggest that the heating event of 2004–2010 was the result of changed permeability conditions, rather than change in the heat supply from the deeper magmatic source. Within this scenario, cooling causes shut down of lower sectors and re-establishment of pathways located towards the crater rim, causing fracturing, increased seismicity and heat flow in these regions. This is consistent with the zone of rejuvenation (which lies towards and at the rim) being the most favourable location for fracturing given the stress field of the Fossa cone Sch?pa et al. (J Volcanol Geotherm Res 203:133–145, 2011); it is also the most established zone, having been active at least since the early twentieth century. Our data show the value of deploying multi-disciplinary geophysical campaigns at degassing (fumarolic) hydrothermal systems. This allows more complete and constrained understanding of the true heat loss dynamics of the system. In the case study presented here, it allows us to distinguish true heating from apparent heating phases. While the former are triggered from the bottom-up, i.e. they are driven by increases in heat supply from the magmatic source, the latter are triggered from the top-down, i.e. by changing permeability conditions in the uppermost portion of the system to allow more efficient heat flow over zones predisposed to fracturing. 相似文献