Test results of railway ballast for bearing capacity calculations

This paper presents the results of field and laboratory tests of railway ballast.Field tests were aimed to study vibrational acceleration of ballast particles and ballast layer stressed state in terms of train traffic with heavy axle loads.The test results are vibrational acceleration and stress values distribution in ballast layer and experimental relationships of vertical and horizontal vibroaccelerations damping in terms of train operation with axle load up to 300 kN.Laboratory stabilometer tests were directed to study the change of ballast strength properties due to vibrodynamic impact and shows that for dynamic loading with 10,25,55 Hz frequencies vibrodynamic impact influences strength properties insignificantly and coincides with the accuracy of test equipment.Stated test results provide references for calculation of ballast and sub-ballast bearing capacity.     

Estimation of seismic hazard and risks for the Himalayas and surrounding regions based on Unified Scaling Law for Earthquakes

To estimate seismic hazard, the basic law of seismicity, the Gutenberg–Richter recurrence relation, is applied in a modified form involving a spatial term: $\log N\left( {M,\;L} \right) = A - B\left( {M - 5} \right) + C\log L$ , where N(M,L) is the expected annual number of earthquakes of a certain magnitude M within an area of linear size L. The parameters A, B, and C of this Unified Scaling Law for Earthquakes (USLE) in the Himalayas and surrounding regions have been studied on the basis of a variable space and time-scale approach. The observed temporal variability of the A, B, and C coefficients indicates significant changes of seismic activity at the time scales of a few decades. At global scale, the value of A ranges mainly between ?1.0 and 0.5, which determines the average rate of earthquakes that accordingly differs by a factor of 30 or more. The value of B concentrates about 0.9 ranging from under 0.6 to above 1.1, while the fractal dimension of the local seismic prone setting, C, changes from 0.5 to 1.4 and larger. For Himalayan region, the values of A, B, and C have been estimated mainly ranging from ?1.6 to ?1.0, from 0.8 to 1.3, and from 1.0 to 1.4, respectively. We have used the deterministic approach to map the local value of the expected peak ground acceleration (PGA) from the USLE estimated maximum magnitude or, if reliable estimation was not possible, from the observed maximum magnitude during 1900–2012. In result, the seismic hazard map of the Himalayas with spatially distributed PGA was prepared. Further, an attempt is made to generate a series of the earthquake risk maps of the region based on the population density exposed to the seismic hazard.     

Finite-fault slip models for the 15 April 1979 (Mw 7.1) Montenegro earthquake and its strongest aftershock of 24 May 1979 (Mw 6.2)

We revisit the April 1979 Montenegro earthquake sequence to invert for finite-fault slip models for the mainshock of 15 April 1979 (M_w 7.1) and of the strongest aftershock of 24 May 1979 (M_w 6.2) using P, SH and SV waveforms, retrieved from IRIS data center. We also used body waveform modelling inversion to confirm the focal mechanism of the mainshock as a pure thrust mechanism and rule out the existence of considerable strike slip component in the motion. The mainshock occurred along a shallow (depth 7 km), low angle (14°) thrust fault, parallel to the coastline and dipping to the NE. Our preferred slip distribution model for the mainshock indicates that rupture initiated from SE and propagated towards NW, with a speed of 2.0 km/s. Moment was released in a main slip patch, confined in an area of L  50 km × W  23 km. The maximum slip ( 2.7 m) occurred  30 km to the NW of the hypocenter (location of rupture initiation). The average slip is 49 cm and the total moment release over the fault is 4.38e19 Nm. The slip model adequately fits the distribution of the M_w ≥ 4.3 aftershocks, as most of them are located in the regions of the fault plane that did not slip during the mainshock. The 24 May 1979 (M_w 6.2) strongest aftershock occurred  40 km NW of the mainshock. Our preferred slip model for this event showed a characteristic two-lobe pattern, where each lobe is  7.5 × 7.5 km². Rupture initiated in the NW lobe, where the slip obtained its maximum value of 45 cm, very close to the hypocenter, and propagated towards the south-eastern lobe where it reached another maximum value — for this lobe — of 30 cm, approximately 10 km away from the hypocenter. To indirectly validate our slip models we produced synthetic PGV maps (Shake maps) and we compared our predictions with observations of ground shaking from strong motion records. All comparisons were made for rock soil conditions and in general our slip models adequately fit the observations especially at the closest stations where the shaking was considerably stronger. Through the search of the parameter space for our inversions we obtained an optimum location for the mainshock at 42.04°N and 19.21° E and we also observed that better fit to the observations was obtained when the fault was modeled as a blind thrust fault.     

Strike-slip motions in the Gulf of Siğaçik (western Turkey): Properties of the 17 October 2005 earthquake seismic sequence

The October 2005 series of earthquakes that occurred in the Gulf of Siğaçik (western Turkey) reveal the operation of pure strike-slip faults, as evidenced from the 49 focal mechanisms we determined, in a region dominated by N–S extension and bounded by well-documented graben structures. The sequence is characterized by the occurrence of three moderate size events (17 October 2005, 05:45 UTC, Mw 5.4; 17 October 2005, 09:46 UTC, Mw 5.8; and 20 October 2005, 21:40 UTC, Mw 5.8) with an eastward propagation and close spatial separation (< 6 km). We relocated over 200 aftershocks, combining phases from the Greek and Turkish seismological networks, which align roughly in a NE–SW cloud, but considerably spread after the first day of the sequence, indicating the simultaneous activation of multiple structures nearly orthogonal to the main rupture. It is hard to relate the occurrence of the events to any of the previously mapped faults in the region. The region of occurrence is a well-known geothermal area which implies that it is in a very unstable state, with the fault systems close to rupture and very sensitive to stress perturbations. Here we showed that the sequence is adequately explained by static stress triggering. It is worth noting that this sequence, though moderate in magnitudes, provides stronger evidence for the operation of sub-parallel strike-slip faults in the central Aegean Sea–western Turkey, north of the volcanic arc, which seem to be optimally oriented in the regional stress field and facilitate the Anatolia motion into the Aegean Sea.     

Pleistocene mammal faunas of Eastern Europe

Systematic studies of the Pleistocene mammal assemblages of Eastern Europe have been carried out for more than a century, and they elucidated evolutionary changes and ascertained chronological sequence of the faunas. The available evidence on fossil mammals from Eastern Europe allows differentiation of 7 complexes of large mammals. These complexes represent 15 assemblages and their phases distinguished for small mammals. The appearance of new taxa of different rank provides the basis for identification of the principal stages in mammal evolution. Multi-disciplinary studies of fossil mammal localities have made it possible to correlate theriological data with the main events of the Pleistocene (such as glacials and interglacials) by comparison between geological, geochronological and palaeontological data.Interglacial and periglacial mammal faunas of different age have been defined on the basis of their structural characteristics and geographical distribution. Two types of mammal assemblages are recognised: zonal interglacial and periglacial assemblages specific to glacial periods. In the first type, each zonal assemblage is dominated by a single ecological group of mammals. A distinctive feature of the second type is the co-existence of animals belonging to different ecological groups and inhabiting different natural environments.     

Single-crystal Raman spectra of YAlO<Subscript>3</Subscript> and GdAlO<Subscript>3</Subscript>: comparison to several orthorhombic ABO<Subscript>3</Subscript> perovskites

Room-temperature-polarized single-crystal Raman spectra have been measured for both GdAlO₃ and YAlO₃. Both aluminates crystallize in the orthorhombic (Pbnm) perovskite structure. Of the 24 possible Raman modes in 4 symmetries, 20 and 17 modes were observed for gadolinium and yttrium aluminates, respectively. Comparisons of the Raman spectra of these two aluminates to those of 28 other orthorhombic ABO₃ perovskites revealed remarkably similar spectral patterns, regardless of chemistry or valency of the cations. Closer examination of the effect of mass, valencies, and size of the cations on the Raman spectra versus composition revealed that for the observed modes, the A cation plays the dominant role in determining the Raman shift. In particular, the one to two lowest energy modes in each symmetry are determined by cation mass and valency no matter what the chemistry. For some perovskites with common A cations, higher energy modes were also strikingly similar. In particular, the calcium perovskites had almost all A_g modes at the same energies despite the greatly varying B cations. The second to the lowest mode in A_g and B_1g depended only on A cation mass for all perovskites. The volume plays a minor role throughout but is hard to separate from mass effects because the most massive cations are also the largest. However, if the B-cation is common, for example, aluminates or ferrites, the volume has a minor effect on the higher energy modes. These trends were not observed for all perovskites. Notable exceptions were found if a perovskite is near a phase transition or metastable, as found for three manganites. The effect of increased valency of the A cation from 2–4 to 3–3 perovskites expresses itself as relatively larger Raman shifts for the lowest energy modes. Analog studies of MgSiO₃ perovskites should be undertaken with only 2–4 perovskites. The increased understanding for the mode distributions of perovskites allows for better estimates of their thermodynamic properties through vibrational modeling.     

Impacts of changing climate on the hydrology and hydropower production of the Tagus River basin

The Tagus River basin is an ultimately important water source for hydropower production, urban and agricultural water supply in Spain and Portugal. Growing electricity and water supply demands, over‐regulation of the river and construction of new dams, as well as large inter‐basin and intra‐basin water transfers aggravated by strong natural variability of climate in the catchment, have already imposed significant pressures on the river. The substantial reduction of discharge is observed already now, and projected climatic change is expected to alter the water budget of the catchment further.In this study, we address the effects of projected climate change on the water resources availability in the Tagus River basin and influence of potential changes on hydropower generation of the three important reservoirs in the basin. The catchment‐scale, process‐based eco‐hydrological model soil and water integrated model was set up, calibrated and validated for the entire Tagus River basin, taking into account 15 large reservoirs in the catchment. The future climate projections were selected from those generated within the Inter‐Sectoral Impact Model Intercomparison Project. They include five bias‐corrected climatic datasets for the region, obtained from global circulation model runs under two emissions scenario – moderate and extreme ones – and covered the whole century. The results show a strong agreement among model runs in projecting substantial decrease of discharge of the Tagus River discharge and, consequently, a strong decrease in hydropower production under both future climate scenarios. Copyright © 2016 John Wiley & Sons, Ltd.     

Use of rubberised backfills for improving the seismic response of integral abutment bridges

Reuse of the 1.5 billion waste tyres that are produced annually is a one of the major worldwide challenges, as waste tyres are toxic and cause pollution to the environment. In recognition of this problem, this paper introduces the reuse of tyres, in the form of derived aggregates in mixtures with granulated soil materials, as previous studies indicated the potential benefits of these materials in the seismic performance of structures. The objective of the present research study is to investigate whether use of rubberised backfills benefits the seismic response of Integral Abutment Bridges (IABs) by enhancing soil-structure interaction (SSI) effects. Numerical models including typical integral abutments on surface foundation with nonlinear conventional backfill material and its alternative form as soil-rubber mixtures are analysed and their response parameters are compared. The research is conducted on the basis of parametric analysis, which aims to evaluate the influence of different rubber-soil mixtures on the dynamic response of the abutment-backfill system under various seismic excitations, accounting for dynamic soil-abutment interaction. The results provide evidence that the use of rubberised backfill leads to reductions in the backfill settlements, the horizontal displacements of the bridge deck, the residual horizontal displacements of the top of the abutment and the pressures acting on the abutment, up to 55, 18, 43 and 47 % respectively, with respect to a conventional backfill comprising of clean sand. Small change in bending moments and shear forces on the abutment wall is also observed. Therefore, rubberised backfills offer promising solution to mitigate the earthquake risk, towards economic design with minimal damage objectives for the resilience of transportation networks.     

Similarity and regional differences in Quaternary arvicolid evolution in Central and Eastern Europe

Because of their rapid evolution and abundant fossil record, arvicolid molars are commonly employed in Quaternary biostratigraphy. In addition, with their extensive geographical ranges these fossils often permit interregional faunal correlations. However, as a pre-condition for such correlations it has to be established that the occurrences are really time parallel in the different regions. This paper deals with the particular comparison of arvicolid records from Central and Eastern Europe. In most of the earliest and latest records of the species investigated similarities in the spectrum of accompanying species can be observed. In some cases endemism (Ungaromys, Ellobius, Eolagurus, Villanyia, several Pliomys species) or different taxonomic interpretations do not provide a sufficient base for comparison. Only for a few taxa can clear biostratigraphical differences of ranges be recognised (mainly Mimomys savini-Arvicola and various lineages within the genus Microtus). In some cases, differences in the chronostratigraphical ranges are possibly caused by the lack of a geological and palaeomagnetic framework for most of the Central European localities.