Geotechnical Factors in Recent Earthquake-Induced Structural Failures in Greece

A review is made of geotechnical factors that played an important role in three recent earthquake-induced failures, two of which were deadly. The first two catastrophes concern two five-storey hotels that collapsed during the “Alkyonides earthquake” of 24 February 1981 (M=6.7) and the “Egion earthquake” of 15 June 1995 (M=6.2). The third failure is the collapse of a multi-storey factory caused by the “Athens earthquake” of 7 September 1999 (M=5.9). In the first two catastrophes, ground subsidence was estimated by two different methods and was found to be of the order of 0.13 to 0.46 m. These estimates are based on tentative assumptions that should be reviewed and possibly revised. Considerable differential settlements must have existed before the earthquake, as there were no basements that would have attenuated vertical loading and so even a moderate additional differential settlement could cause failure. In the third case, the structure was built near the edge of a steep slope of clayey soil. The co-seismic shear displacement caused the footings resting on the sliding mass to settle, thus causing severe distortions to the structure

LANDSCAPE GEOMORPHOLOGICAL EVOLUTION AND COASTAL CHANGES: A CASE STUDY OF COASTAL EVOLUTION IN THE WESTERN PATRAIKOS GULF AREA, WESTERN GREECE

Γεωλογικές και γεωμορφολογικές έρευνες διεξήχθησαν στο δυτικό τμήμα των νότιων ακτών του Πατραϊκού κόλπου και τα ευρήματα μελετήθηκαν σε σχέση με αρχαιολογικά ευρήματα στην ίδια περιοχή. Τα χαρακτηριστικά των αρχαιολογικών ευρημάτων και οι αποθέσεις στις οποίες βρίσκονται, δύναται να δίνουν στοιχεία για την πηγή, τη μεταφορά και την ηλικία τους. Βρέθηκαν θαμμένα σε αποθέσεις ποτάμιας και αλλουβιακής ιζηματογένεσης. Η ηλικία τους εκτιμήθηκε από αρχαιολόγους και κυμαίνεται από τον 7ο αιώνα π.Χ. έως και τον 4ο αιώνα μ.Χ. Η γεωμορφολογία και η αρχαιολογία έχουν ισχυρούς ιστορικούς και μεθοδολογικούς δεσμούς και μπορούν να προσφέρουν πληροφορίες για τις διαδικασίες και την έκταση των περιβαλλοντικών αλλαγών. Προσφέρουν επίσης τα εργαλεία για την ανάλυση του ρυθμού ιζηματογένεσης, τη σχετική χρονολόγηση και γεωμορφολογική αξιολόγηση της συγκεκριμένης περιοχή όπως και στοιχεία για την χρήση της επιφάνειας του εδάφους, για τις παλαιοπεριβαλλοντικές και κλιματικές συνθήκες. Τα ιζήματα που υποδεικνύουν σημαντικές κλιματικές μεταβολές στις περιοχές με υψηλή υγρασία είναι αλλουβιακές αποθέσεις σημαντικού πάχους που καλύπτουν περιοχές ανθρώπινης δράσης. Υπάρχει στενή συσχέτιση, όπως φαίνεται από τα αρχαιολογικά ευρήματα μεταξύ κλιματικών και περιβαλλοντικών διακυμάνσεων . Η αστάθεια των κλιματικών συνθηκών, προκαλούν αλλαγές στις υδρολογικές συνθήκες με επακόλουθο τη γεωμορφολογική αστάθεια και τη ταφή των κατασκευών.Geological and geomorphological research has been carried out in the western part of the south coast of Patraikos Gulf and the findings were studied in relation to archaeological remains found in the same area. The characteristics of the archaeological findings and the stratigraphical record and the deposits in which they are contained, may originate their source, transportation way and age. The artifacts were contained in fluvial and alluvial deposits under the present land surface. Their age was estimated by archaeologists to be between 7th century BC and 4th century AC. Geomorphology and archaeology have strong historical and methodological links and can provide information about the processes and extent of environmental changes. They also provide the tools for analysing sedimentation rates, relative chronology and geomorphological evaluation of the particular archaeological site as well as clues for land-surface development, paleoenvironmental and climatic conditions. Sediments indicating considerable climatic changes in current humid areas are alluvial deposits of considerable thickness, covering areas with human activity. There is a close correlation, as shown by the archaeological findings between climatic and environmental fluctuations. Since when there is a transition in climatic conditions causing changes in hydrologic conditions with ensuing geomorphological instability and burying the structure

Stacking classifiers for anti-spam filtering of e-mail

We evaluate empirically a scheme for combining classifiers, known as stacked generalization, in the context of anti-spam filtering, a novel cost-sensitive application of text categorization. Unsolicited commercial e-mail, or "spam", floods mailboxes, causing frustration, wasting bandwidth, and exposing minors to unsuitable content. Using a public corpus, we show that stacking can improve the efficiency of automatically induced anti-spam filters, and that such filters can be used in real-life applications

Back Analysis of the Malakassa Landslide Using the Multi-Block Model

During the early hours of 18-02-1995 a landslide occurred at Malakasa, on the 36th kilometer of the highway joining Greece\u27s main cities, Athens and Thessaloniki. The computed deformed geometry using this model agrees reasonably well with that measured. The back-estimated soil strength of 16o is in the range of the measured values (8-19o). Finally, state-of-the-art stability analyses, using the back-estimated residual soil strength, illustrated that the location of the slip surface can be predicted if it is assumed that only the saturated soil below the water table loses its strength

Back Analysis of the Liquefaction Failure at King Harbor Redondo Beach, California

During recent earthquakes small dams and embankments suffered large settlements as a result of earthquake-induced liquefaction. One such case is the mole embankment that settled about 1.2m and was displaced horizontally by about 2m at King Harbor Redondo Beach, California as a result of the Northridge earthquake of 1994 (Kerwin and Stone, 1997). The conventional sliding-block model has shortcomings in back-estimating the critical acceleration and corresponding strength of such earthquake-induced slides when seismic displacement is large. The reason is that the change on geometry of the sliding mass, that greatly affects the seismic displacement, is not modeled. Stamatopoulos et al (2000) proposed a two-body sliding system that models this change in geometry. In the present paper, the Stamatopoulos et al (2000) sliding system model is used to back-estimate the residual shear strength of the mole embankment at King Harbor Redondo Beach. Then, the correlation of the residual soil strength and the blow count resistance of the SPT of this case is compared to the relationship that has been proposed by Seed and Harder (1990)

Critical Acceleration and Seismic Displacement of Vertical Gravity Walls By a Two Body Model

Under the assumption that as a result of earthquake loading the backfill behind a gravity wall reaches an active state, and with further increase in the earthquake acceleration the wall slides outwards, the soil-wall system consists of two bodies, each sliding along a different inclination: (a) the active soil wedge that slides with the inclination of least resistance in the backfill, and (b) the wall that slides along the soil-wall boundary at the base. This paper first gives the equation of motion of the 2-block sliding system described above that models the seismic response of vertical gravity walls retaining dry sand. Then, using the principle of limit equilibrium it gives analytical expressions giving (a) the angle of the prism of the active soil wedge, and (b) the corresponding value of the critical acceleration. Finally, differences between the predicted displacement by the new model and those of Newmark’s sliding-block model are detected and discussed

Improvement of Dynamic Soil Properties Induced by Preloading Verified by a Field Test and Embankment Failure

The results of an elaborate field preloading study on a liquefaction-susceptible site are presented. Preloading was applied by a temporary embankment 9m high. Prior and after preloading, borings with standard penetration tests, cone penetration tests and geophysical studies were performed. During the process of embankment construction and demolition, settlements, excess pore pressures and vertical and horizontal stresses were recorded versus time at different locations. A partial embankment failure occurred during the preloading process. A method predicting failure during the construction of the preload embankment based on excess pore pressure measurements is proposed and verified

Management of multiple, late onset complications in a 33-year-old female, with a ventriculoperitoneal shunt and crohn\u27s disease

Numerous complications can occur after the placement of a venticuloperitoneal shunt. The late onset of an autoimmune disease such as Crohn\u27s disease can be the disruptive factor for a previously well functioning shunt. A 33-year-old female with a ventriculo-peritoneal shunt since the age of 7, as well as Crohn\u27s disease since the age of 25, presented in the ER with dysuria, long-lasting fever and intermittent severe headache. The patient underwent a CT scan of the chest, abdomen and brain. An enlargement of the ventricular system was revealed, suggesting malfunction of the shunt. Simultaneously, the abdominal scan revealed an abnormal course of the peritoneal catheter of the shunt in the lower abdomen, inside the bladder. The existence of the catheter inside the bladder was confirmed and filmed during a cystoscopy and was attributed to the several inflammations and surgeries performed for the treatment of Crohn\u27s disease.The absence of an obvious stenosis of the aqueduct, the early immunodeficiency due to Azathioprine and the multiple abdominal surgeries made the treatment selection a complex algorithm for the neurosurgeon

The Role of Levocarnitine in the Management of Valproic Acid Intoxication: A Case-Based Review

The administration of L-carnitine to patients with VPA intoxication and CNS depression with normal ammonia concentrations has a rationale, on the grounds that it is a safe compound with no severe adverse effects reported. Herein, we present a case of valproate poisoning with normal ammonia levels and discuss about the therapeutic as well as the prophylactic potential of L-carnitine administration in such cases

Subsidy policies and vertical integration in times of crisis: Can two virtues produce an evil?

Vertical integration in an environment without foreclosure, or more generally without any mechanisms that restrict competition among firms, and subsidization of firms' production are two separate mechanisms that raise consumer welfare, and both have been proposed as antidotes to certain aspects of the current economic crisis caused by COVID-19. In this paper we show that the interplay of the two can, surprisingly, be harmful for consumers. We consider a two-layer imperfectly competitive industry where each downstream firm purchases an input from its exclusive upstream supplier, in the presence of a welfare-maximizing government. We allow one (or more than one) of the downstream firms to integrate with its upstream counterpart and we identify two opposite resulting effects: on the one hand, integration alleviates the double marginalization problem and raises industry output and on the other, it alters the government's optimal subsidy policy in a way that reduces output. It turns out that the latter effect dominates the former and thus integration leads to lower market output and consumer surplus. This holds irrespective of the mode of downstream market competition (quantities or prices) or the nature of commodities (homogeneous or differentiated). It also holds when the fiscal policy of the government is subject to social costs. Our conclusions are in particular relevant to the current pandemic period which spurs heavy subsidization of firms and reformulation of firms' vertical relations