G. Di Crescenzo

Vulnerability assessment for reinforced concrete buildings exposed to landslides

The methodologies available for the analytical quantification of the vulnerability of buildings which are subject to actions resulting from slope instabilities and landslides are relatively limited in comparison with other components of quantitative landslide risk assessment. This paper provides a general methodology for calculating the vulnerabilities of reinforced concrete frame structures that are subject to three types of slope instability: slow-moving landslides, rapid flow-type slides and rockfalls. The vulnerability is expressed using sets of fragility curves. A description of the general framework and of the specialised procedures employed is presented here, separately for each landslide mechanism, through the example of a single-bay one-storey reinforced concrete frame. The properties of the frame are taken into account as variables with associated uncertainties. The derived vulnerability curves presented here can be used directly by risk assessment practitioners without having to repeat the procedure, given the expected range of landslide intensities and for similar building typologies and ranges of structural characteristics. This permits the applicability of the calculated vulnerability to a wide variety of similar frames for a range of landslide intensity parameters.

Karst processes and slope instability: some investigations in the carbonate Apennine of Campania (southern Italy)

Abstract Some investigations carried out in the Campania Region (southern Italy) are shown concerning instability phenomena, the development of which is strongly influenced by karst. The widespread presence of carbonate massifs close to important urban centres with dense road networks creates high-risk situations in many settings of this region. Such phenomena can have very different dimensions, origin and geomorphological development, and can be traced back to the action of hypogean and epigean karst and to complex interactions with other erosional processes. In particular, among the hypogean forms, we have analysed collapse sinkholes that have developed on carbonate slopes, especially along fault lines where there are aquifers and ascent of mineralized fluids, and which are sometimes connected to strong seismic events. Among the forms connected to epikarst processes, the origin of pinnacles has been investigated. They are isolated rock pillars, whose origin depends on a particular interaction between the geostructural characteristics of the masses and the process of karstic dissolution. Moreover, a wide variety of morphologies exist that are related to the interaction between epigean and hypogean karst and other typologies of erosional processes. Among these one group is represented by caves on carbonate slopes developed in cataclastic zones, where a slow karstic process leads to the formation of upwards caves, with dimensions of some decametres, and consequently to the high production of debris downhill. Similarly, this process has been observed along slopes set on talus. Finally, the complex combination of the karstic phenomenon with the erosional wave action forms both caves and natural rock arcs along the coasts.

Volume estimate of flow-type landslides along carbonatic and volcanic slopes in Campania (Southern Italy)

Recent studies on flow-type landslides in pyroclastic deposits have been performed to identify potential source areas and the main depositional mechanisms. Interesting methods for mapping landslide susceptibility have also been proposed. Since the potential volume of flow-type landslides is a measure of event magnitude, hence of considerable use in hazard assessment, we propose a method to estimate the potential volume for the morphometric analysis of 213 flow-like landslides occurred in Campania in recent centuries. First, our data show that the height, H, of the detachment and erosion-transport zones (i.e. the difference in height between the top of source area and a point, the first break at the foot of the slope, where the deposition stars to take place and the landslide loses velocity) and the area, Af, of the same zones are linked by a mathematical function. Secondly, only part of the entire thickness of the pyroclastic material on the slope is involved. To define the potential volumes of the flow-type landslides, we analysed slopes, both in volcanic and carbonatic contexts, considering both channelled and unchannelled flow-type landslides. The most susceptible areas are identified by using a landslide-triggering susceptibility map, and then in each case the height H was estimated. This height is the difference in level between the point on the slope with highest susceptibility and the first break at the foot of the slope. Using the statistical correlation between H and Af, both calculated for historical landslides, we evaluate the area of a potential landslide on a slope. Finally, potential volumes are calculated by using Af and a constant thickness of the pyroclastic cover for the whole slope. This method could represent a useful tool to detect the main areas where risk mitigation works are required.

Probabilistic Assessment of Debris Flow Peak Discharge by Monte Carlo Simulation

AbstractThe topographic and hydrologic parameters involved in the estimation of the debris flow peak discharge in a classical approach are usually assumed to be deterministic. As a result, in such approaches, the only uncertainty in the evaluation of peak discharge is the evaluation of rainfall intensity and frequency. The present study aims to provide a probabilistic approach for estimating the debris flow peak discharge through the use of a Monte Carlo simulation method. Studies on such landslides in pyroclastic deposits have been performed in order to identify potential source areas and the main depositional mechanisms. The standard Monte Carlo simulation is used in order to propagate the uncertainties in different paramaters, related to hydrographic basin modeling, and to obtain a probability distribution for the peak discharge, related to a given return period. As a numerical example, the peak discharge of debris flow in the basin of the Corbara Stream, located in the municipality of Salerno in south...

The Assessment Of Mudflow Peak Discharge Through A Monte Carlo Simulation Method

The present study introduces a probabilistic approach able to estimate the mudflow peak discharge through the use of a Monte Carlo simulation method. In a classical deterministic approach, for a specific catchment, the parameters involved in estimation of the peak flow (topographical, hydrological parameters) are assumed to be known. As a result, in such approaches, the only source of uncertainty in evaluation of the peak discharge is due to rainfall intensity and frequency estimation. In this work, the standard Monte Carlo simulation is used in order to propagate also the unceratinties in various parameters related to hydrographic basin modelling and to obtain a probability distribution for the peak-discharge flow for a given return period. As a test case, the peak discharge of a mudflow in the basin of the Mandrizzo River, located in the town of Cava dei Tirreni in Southern Italy, is evaluated.