Deltaic soil behavior classification using CPTu records—Proposed approach and applied to fifty-four case histories

For the past four decades, the CPT has played a key role in onshore and offshore soil investigations. One of the main applications of cone penetration test (CPT) is the soil behavioral classification. Most of the developed methods for soil identification using CPT and CPTu (piezocone) data are well categorized for common soils, such as clays, silts, and sands. Soils with low resistance or more compressibility generally involve problems in geotechnical engineering practice and construction projects. Consequently, these unusual deposits require further evaluation and more detailed data. Five major groups of problematic soils including: liquefiable, sensitive, peaty, collapsible, and expansive soils have been considered in this study. One hundred and forty CPT and CPTu test records were collected from fifteen countries. Sixty-one of the records are related to difficult soils. A brief comparison is performed for currently used soil behavioral classification charts, such as by Campanella et al. (1985 Campanella, R. G., P. K. Robertson, D. Gillespie, and J. Greig. 1985. Recent developments in in-situ testing of soils. Proceedings of 11th International Conference on Soil Mechanics and Foundation Engineering, ICSMFE, San Francisco, Vol. 2, 849–54. [Google Scholar]), Robertson (1990 Robertson, P. K. 1990. Soil classification using the cone penetration test. Canadian Geotechnical Journal 27 (1):151–58. doi:10.1139/t90–014[Crossref], [Web of Science ®] , [Google Scholar]), Jefferies and Davies (1991 Jefferies, M. G., and M. P. Davies. 1991. Soil classification using the cone penetration test: Discussion. Canadian Geotechnical Journal 28 (1):173–76. doi:10.1139/t91–023[Crossref], [Web of Science ®] , [Google Scholar]) and Eslami and Fellenius (1997 Eslami, A., and B. H. Fellenius. 1997. Pile capacity by direct CPT and CPTu methods applied to 102 case histories. Canadian Geotechnical Journal 34 (6):886–904. doi:10.1139/cgj-34–6-886[Crossref], [Web of Science ®] , [Google Scholar]). Analysis based on CPT data indicates that a few commonly used charts recognize relatively well problematic deposits. However, further studies are needed to increase the accuracy and capability of methods. Existing charts have some problems due to the limitations of the nature of rectangular charts based on two axes. A new format of classification chart, i.e., triangular form containing cone tip resistance (q_c), sleeve friction (f_s), and pore pressure (u₂) is proposed for soil identification which can be realized in practice. The proposed chart with more accuracy and less scattering of data than the previous charts is able to identify soil types particularly for deltaic soils.     

Microbial activity promotes the enrichment of cobalt over nickel on hydrogenetic ferromanganese crusts

The different mineral phases of the ferromanganese (Fe–Mn) crusts stem from the interaction of biotic and abiotic components. It is therefore vital to study the activity of these components to decipher their contribution to the enrichment/depletion of metals in the crust. Thus, the present study examined sorption and release of Co and Ni by Fe-Mn crusts with associated microbial communities in the presence and absence of the metabolic poison sodium azide (15?mM). The study was conducted in the presence (G⁺) and absence (G^?) of added glucose (0.1%) at temperatures of 4?±?1°C and 28?±?2°C. Results showed that the microbial community had maximal sorption of Co of 66.12?µg?g^?1 at 4?±?1°C in the absence of added glucose and 479.75?µg?g^?1 at 28?±?2°C in the presence of added glucose. Maximum sorption of Ni in the absence of added glucose was 1.89?µg?g^?1 at 4?±?1°C and release of Ni was 51.28?µg?g^?1 in the presence of added glucose. Under abiotic conditions with 15?mM sodium azide as a metabolic inhibitor, significant amounts of Co and Ni were released in the G⁺ medium. Total cell counts on the Fe-Mn crust in the presence of added glucose increased by an order of magnitude from 10⁶ to 10⁷ cells g^?1 and in the absence of added glucose remained within the order of 10⁶ cells?g^?1 irrespective of temperature of incubation. Microscopic observation of the samples from biotic incubations showed numerous bacterial cells, exopolysaccharides, and structures resembling secondary minerals formed by bacteria. The results indicate that bacteria promote the enrichment of Co and Ni on the hydrogenetic Fe-Mn crusts by sorption processes and release of Ni by reductive dissolution of the oxides. The higher enrichment of Co than Ni is attributed to the way in which microbes interact with the metals.     

Modelling of sediment movement in the surf and swash zones

Under the action of marine currents, non-cohesive sediments evolve by bed-load, by saltation or suspension depending on their granulometry. Several authors have considered that the movement of sediment...     

Features of wind waves at the southeastern coast of Sakhalin according to bottom-pressure measurements

The results of wind-wave measurements with bottom-pressure sensors are discussed. These measurements were performed at the southeastern coast of the Island of Sakhalin in 2006–2009. The problems of converting data obtained with these sensors into water-level displacent in the context of the linear theory are noted. Twenty records with a duration of 2 weeks to 3 months were obtained. These records contain from 150000 to 1200000 waves for three different observation points located at the southeastern coast of Sakhalin in the regions of the village of Vzmor’ye, Lake Izmenchivoye, and the Cape of Ostryi. The estimates obtained for wave-height distributions were approximated by the Weibull distribution. They were compared to the theoretical Rayleigh, Forristall, Weibull, and Glukhovskii distributions. As one would expect, in the region of small wave heights, all distributions prove to be close to one another, and, for large wave heights, the Weibull distribution is preferred.     

Bayesian classification of the ice cover of the Arctic seas

A classification of sea ice in the Arctic by age (multiyear; first-year; and first-year deformed ice, nilas, etc.) is developed based on the Bayesian approach using satellite radar data and taking into account regional peculiarities of these types of ice for different sectors of the Arctic. Estimations of a priori probabilities for each ice type, which are required for the use of the Bayesian classification, are obtained by the analysis of ice charts in the Arctic seas developed at the AARI in 2008–2013 using satellite data. A posterior probabilities are estimated visually by an expert. Types of sea ice distinguished by the expert on satellite images make it possible to create sample values of the radar-scattering cross section (RSCS). Examples of the proposed Bayesian classification of ice in the Laptev Sea according to Envisat satellite data are given.     

Manifestations of the rim current,coccolithophore blooms,and continental runoff in the long-term monthly mean distributions of satellite reflectance coefficients of the Black Sea

Based on the archived data of the ocean color scanner MODIS-Aqua for 2003–2011, we constructed the long-term monthly mean distributions of the reflectance Rrs of the Black Sea for April, May, June, and September in order to visualize the contributions of seasonal factors to the long-term variability of the basin’s images. In April, the Rim Current’s branch west of 34° E is visualized by higher Rrs in different regions of the visible spectrum due to the transport of suspended matter caused by intensification of the Rim Current during the winter-spring period. During the June coccolithophore “blooms,” the long-term Rrs level is 2–3 times higher when compared to the previous and subsequent months. This excess is particularly considerable outside the shelf and coastal areas. The open sea Rrs distribution in June features horizontal inhomogeneity. The seasonal trend of the Rrs spectra on the Black Sea NW shelf is explicitly related to the annual cycle of the continental runoff effects.     

Comparison of Near Coastal Significant Wave Height Measurements from SARAL/AltiKa with Wave Rider Buoys in the Indian Region

Significant Wave Height (SWH) measurement data from the AltiKa Radar Altimeter (RA) for the first 13 cycles of satellite coverage are compared with the SWH from Wave Rider Buoys (WRB) located at nine stations along the Indian coast to assess the performance of the altimeter over the coastal region. AltiKa SWH observations within a 30-minute interval and 50 km distance from WRBs are found to be over estimated by 6%, the Root Mean Square Error (RMSE) is 0.36 m, the Scatter Index (SI) is 26%, and the correlation coefficient (r) is 0.91. Relaxing the distance criteria by 50 km leads to increase in RMSE and deterioration of r to 0.89. There is a marked difference in the statistics on the comparison pairs pooled separately for the buoys near west and east coasts, with the latter showing RMSE error 26% more than the former. The method of Cressman weights adopted to correct for the errors arising out of the temporal and spatial differences in altimeter and buoy data comparison pairs resulted in reduction of RMSE by 5% and 25%, respectively, for the 30-minute and 50 km criteria and 4% and 56% for the 30-minute and 100 km criteria.     

Lidar sounding of the optical parameter of atmospheric turbulence

The operation of a lidar intended for clear air turbulence (CAT) positioning on the basis of the backscatter enhancement (BSE) effect is analyzed using a turbulence model with a power-law spectrum. Systematic distortions occurring due to a need to regularize the lidar positioning problem solution are estimated. It is shown that the effect of molecular viscosity of air on the positioning result can be neglected if the wave parameter, which characterizes the diffraction manifestation, is higher than 3. This corresponds to sounding ranges of more than 1 km for optical or UV lidars. The analysis results show that the BSE lidar positioning accuracy weakly depends on the exponent in the turbulence spectrum in regions of severe turbulence. The results can justify a physical experiment for the design of an aircraft system for the lidar detection of CAT regions ahead of the flight course.