Stability analysis of a recurring soil slope failure along NH-5, Himachal Himalaya,India

The repetitive soil slope failure along the National Highway (NH)-5 in Jhakri region of Himachal Pradesh, India draws frequent concern due to heavy damage and traffic disruption almost every year. Being only linking route from border district to the nearby land area, stability of the road-cut slopes along this highway is of major concern in regard to safe transportation. Absence of any previous stability investigation of this recurring slope failure calls for an integrated geotechnical and numerical approach in order to understand the instability factors. The geotechnical analysis has been performed to determine the inherent properties of soil materials which affect the stability of existing slope. An event-specific antecedent rainfall threshold has been suggested to quantify the relationship between rainfall and slope failure. A two-dimensional limit equilibrium method has also been executed to visualize the scenario of pre- and post-failure stability of the slope. On the basis of limit equilibrium analysis, it has been inferred that slope geometry is a major affecting parameter that influences the failure pattern. Moreover, preventive measures through benching and soil nailing have also been proposed and validated through limit equilibrium analysis for long-term stability and safe transportation.     

Assessment of Vulnerability of Rock Slope Considering Material and Seismic Variability

The Ghawar anticline (GA) is the super-giant anticline belonging to a set of giant anticlines called the Rayn anticlines (RA) developed in the Eastern Province (EP), Saudi Arabia. The RA is situated within the Arabian block microplate forming the distant foreland of the Zagros. For the first time, using the ‘Reviewed ISC Earthquake Catalogue’ for the period of 1970-2010, it is demonstrated that the EP crust is seismogenic down to a depth of ～15 km or more and has a typical surface width of ～220 km; this width is ostensibly six-times wider than that of GA. The Saudi Geological Survey (SGS) Earthquake Network Catalogue is utilized to study local seismicity. The GA is locally seismically active such that 826 events have occurred during the period of 2005-2010, with a maximum magnitude of ML 4.24. Magnitude completeness (Mc) analysis, based on the assumption of self-similarity, suggests that all local earthquakes above a cut-off magnitude of ³2.7 have been detected in EP. Certain basic estimates on the average depth of origin of the induced events and histogram plot on the frequency of induced and ambient (natural) seismicity are illustrated. The induced events came almost in equal proportions from the Uthmaniyah-Hawaiyah and Haradh production divisions belonging to the central and southern oil/gas Fields in GA. Poroelastic parameters of the reservoir are reviewed with respect to the induced seismicity. Focal-depth distribution of events along the strike direction of seismic zones follows the ‘En-Nala axis’ in the GA and is used, together with ISC data, to broadly define the seismogenic crust from a 3D-perspective. Seismic activity below both production divisions is supposedly triggered by hydrocarbon fluid-extraction; locally triggered seismicity shows better correlation to mutually opposite reverse faults transgressing the Haradh and Uthmaniyah-Hawaiyah production divisions under the influence of regional compressive stress oriented along N40°E. Results from four composite focal mechanism solutions also support this contention.     

The Effects of Solar Eclipse of August 1, 2008 on Earth’s Atmospheric Parameters

Several experiments were undertaken at Kolkata (latitude: 22°34′N, longitude: 88°30′E) on the solar eclipse day of August 1, 2008 to observe the effects of the solar eclipse on Fair Weather Field (FWF) and VLF amplitude and phase. The experimental results presented here show significant deviations of the observed parameters from their normal values, as they are determined by the average of the records obtained on 5 days adjacent to the day of the solar eclipse.     

The problem of velocity inversion in refraction seismics: some observations from modelling results

The applicability of seismic refraction profiling for the detection of velocity inversion, which is also known as a low-velocity layer (LVL), is investigated with the aid of synthetic seismogram computations for a range of models. Our computational models focus on the inherent ambiguities in the interpretation of first-arrival time delays or 'skips' in terms of LVL model parameters. The present modelling results reveal that neither the measure nor even the existence of a shadow zone and/or a time shift (skip) in first arrivals is necessarily indicative of an LVL. Besides attenuation effects, the cap-layer velocity gradient is a critical parameter, determining the termination point of the cap-layer diving wave and thus the time skip.
We suggest that shallow LVLs can be delineated more reliably by traveltime and amplitude modelling of coherent phases reflected from their top and bottom boundaries, often clearly observed in the pre- and near-critical ranges in seismogram sections of refraction profiling experiments with a close receiver spacing. We demonstrate the applicability of this approach for a field data set of a refraction profile in the West Bengal Basin, India. The inferred LVL corresponds to the Gondwana sediments underlying the higher-velocity layer of the Rajmahal Traps. This interpretation is consistent with the data from a nearby well in the region.     

Spacetime dynamics of bed forms due to turbulence around submerged bridge piers

Stochastic Environmental Research and Risk Assessment - This work presents a study of spatiotemporal changes of scour-holes around sand embedded submerged circular and non-circular cylinders with...     

Some issues in contextual fuzzy <Emphasis Type="Italic">c</Emphasis>-means classification of remotely sensed data for land cover mapping

Earlier for the hard classification techniques contextual information was used to improve classification accuracy. While modelling the spatial contextual information for hard classifiers using Markov Random Field it has been found that Metropolis algorithm is easier to program and it performs better in comparison to the Gibbs sampler. In the present study it has been found that incase of soft contextual classification Metropolis algorithm fails to sample from a random field efficiently and from the analysis it was found that Metropolis algorithm is not suitable for soft contextual classification due to the high dimensionality of the soft outputs.     

Bioindicator role of tintinnid (Protozoa: Ciliophora) for water quality monitoring in Kalpakkam,Tamil Nadu,south east coast of India

The feasibility of a potential bioindicator based on functional groups of microzooplankton tintinnids for bioassessments of water quality status was studied during southwest monsoon (June to September) along the coastal waters of Kalpakkam, India during 2012–2015. The work highlights the following features (1) tintinnid community composed of 28 species belonging to 11 genera and 9 families, revealed significant differences among the four study sites (2) maximum numerical abundance (2224 ± 90 ind. l^? 1) and species diversity (H′ = 2.66) of tintinnid were recorded towards Bay of Bengal whereas minimum abundance (720 ± 35 ind. l^? 1) and diversity (H′ = 1.74) were encountered in the backwater sites, (3) multivariate analyses [RELATE, Biota-environment (BIOENV) and canonical analysis of principal coordinates (CAP)] reveal that chl a, nitrate and phosphate were the potential causative factors for tintinnid distribution. Based on the results, we suggest that tintinnids may be used as a potential bioindicator of water quality status in marine ecosystem.     

Evaluation of horizontal stiffness of fibre‐reinforced elastomeric isolators

Unbonded fibre‐reinforced elastomeric isolator (U‐FREI) is relatively new seismic base isolator in which fibre layers are used as reinforcement to replace steel shims as are normally used in conventional isolators. Further, the top and bottom end steel connector plates of conventional isolators are also removed. In general, the horizontal response of U‐FREI is nonlinear because of reduction in contact area due to rollover deformation and reduction in shear modulus of isolator under large deformation. Thus, evaluation of horizontal stiffness of U‐FREI is a challenging problem. Most previous studies were focused on the investigation of horizontal response of scaled models of U‐FREIs with low shape factors. A few analytical approaches were suggested for predicting the horizontal response of U‐FREI; but their results were not in good agreement with experimental observations. In the present study, the horizontal responses of prototype U‐FREIs are evaluated under a constant vertical pressure and cyclic loading using both experiments and finite element analysis. Prototype U‐FREIs with different shear moduli and with different shape factors are considered. Finite element simulations of corresponding bonded FREIs are also performed under the same loadings as in U‐FREIs. A rational analytical approach including the influence of rollover deformation and simultaneous reduction in shear modulus is proposed as a basic analytical tool for predicting the horizontal stiffness of FREIs (both bonded and unbonded). It is in reasonably good agreement with the results obtained from experiments and numerical analysis. Copyright © 2017 John Wiley & Sons, Ltd.     

Inter-comparison of model-predicted wave heights with satellite altimeter measurements in the north Indian Ocean

A numerical model based on a wind-wave energy transport formulation of Toba is developed to generate hindcast wave height data for the equatorial and the north Indian Ocean, which is otherwise a data-sparse region. The intercomparison between model-predicted wave heights for three years (1987–1989) obtained utilising analysed surface wind fields' data, and model grid averaged GEOSAT Altimeter significant wave height data showed moderate match, particularly for H_S greater than 1 m.     

Determination of Ocean Wave Period from Altimeter Data Using Wave-Age Concept

This study makes use of the concept of wave age in estimating ocean wave period from space borne altimeter measurements of backscattering coefficient and significant wave height. Introduction of wave age allowed better accounting of the difference between swells and wind waves. Using two years (1998 and 1999) data of TOPEX/Poseidon altimeter and ocean data buoy observations in the Indian Ocean, coefficients were generated for wave period, which were subsequently tested against data for the years 2000 and 2001. The results showed the wave period accuracy to be of the order of 0.6 sec (against 1.3 sec obtained with the semiempirical approach, reported earlier).