Liquefaction Analysis of Sands: Some Interpretation of Seed\u27s K\u3csub\u3eα\u3c/sub\u3e (Sloping Ground) and K\u3csub\u3eσ\u3c/sub\u3e (Depth) Correction Factors Using Steady State Concept

Seed\u27s Liquefaction Assessment Chart (SLAC) correlates the corrected SPT blow count (N1)60 to the cyclic stress ratio required to cause liquefaction for free field level ground conditions. However, the cyclic stress ratio or the liquefaction resistance of a soil under sloping ground (initial static shear) and at depth (high confining pressure) would be significantly different from that derived from the SLAC. To correct the liquefaction resistance for the initial static shear and confining pressure, factors Kα and Kσ are used respectively. The factors have significant influence on the evaluation of liquefaction resistance against earthquake loading and therefore on the final outcome of the design of the structure. The corrections that are available in the state-of-the-art literature and used by the industry are empirical and inappropriate. The Kα and Kσ factors can vary profoundly depending on the initial state of the soil in the q-p-e (stress/void ratio) space and its stress path being in the dilative or contractive domain of the state boundary surface. In this paper, it is demonstrated that it is possible to correlate the correction factors Kα and Kσ to some fundamental parameters, (state parameter, ψ) that govern the strength-deformation of soils using critical/steady state principles

Some trends observed in the deep-sea lobster catches of the vessel "Blue Fin" during the period January '69 to December '71

During the past two decades there have been sporadic attempts to explore the lobster resources especially the deep-sea lobster along the Kerala coast. Even as early as 1901 (Alcock, A) the occurrence of deep-sea lobster off the Travancore coast has been recorded

A Review of the Influence of Initial State Shear (K\u3csub\u3eα\u3c/sub\u3e) and Confining Stress (K\u3csub\u3eσ\u3c/sub\u3e) On Failure Mechanisms and Earthquake Liquefaction of Soils

Geotechnical engineering profession has continued to use the in situ measurement based empirical procedure to perform soil liquefaction analysis. This method was initially developed based on past earthquake performance of level ground sites. For sloping ground and larger depths or confining stress, the method requires appropriate corrections such as Kα for initial static shear and Kσ for confining stress. The recommended correction factors in the current state of practice have been presented by NCEER (National Center for Earthquake Engineering and Research). These recommendations, however, do not distinguish between the distinct shear behavior of soils on the opposite sides of the critical state line. These factors can significantly influence the results and alter the final conclusion and outcome of an analysis. This paper reviews the existing soil liquefaction research data focusing on these factors based on the critical state soil mechanics framework. It is shown that the undrained response of soils with stable yielding during both monotonic and cyclic loading can be correlated with the distance of the initial state from the critical state line. Kα and Kσ are shown to correlate well with this distance. Constant cyclic resistance ratio lines are found to lie parallel to lines of constant initial state. Furthermore, Kσ variation is found to be material specific

The Failure of Teton Dam – A New Theory Based on State Based Soil Mechanics

Teton Dam failed during its first filling on 5 June 1976. The 405-ft high dam was designed and built using modern standards; therefore its failure received considerable scrutiny from engineering experts. Failure mechanisms suggested, included hydraulic fracture, internal erosion, wet-seam theory, and defects in the abutment rock. None of the investigations, however, were able to explain satisfactorily why the dam breached when the reservoir reached EL.5301.7 ft and only in the vicinity of Sta. 14+00 on the right abutment. The investigation here is focused on this crucial aspect of the failure using the modern framework of fundamental “state based soil mechanics”. According to this framework highly compacted soils of low plasticity in an environment of low liquidity index and low confining stress would crack in the presence of high shear stresses. The impervious core (Zone-1) of Teton was constructed of uniform clayey silt of low plasticity and highly compacted and therefore was prone to such a possibility. This paper describes the details of the theory, the investigation, and the conclusions arrived at regarding the potential initiation of Teton failure. Finite element analysis carried out using state based parameters indicate the presence of deep open transverse vertical crack(s) in the core (Zone-1) to a maximum depth of about 32 ft from the crest only in the right abutment and in the vicinity of Sta. 14+00. We conclude that once the water level in the reservoir rose above El 5300.0 ft in the early hours of 5 June 1976 water flowed through the open vertical crack(s), which slowly eroded the crack into a large tunnel leading to the major breach of the dam hours later

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Abatement of mercury pollution in aquatic systems: A biotechnological approach

Mercury has been in use since time immemorial for medicinal, agricultural and industrial purposes. It is widely used in the manufacture of thennometers, fungicides, insecticides, batteries, caustic soda, pulp and paper, urethane plastics and many other purposes. During 1953to 1961,43 people ilied and about 113 were affected with mercury poisoning after consuming mercury contaminated fish in Minamata, Japan. In 1960, in Sweden, methyl mercury accumulation in fish and decrease in the population of birds was noticed. This was attributed to the use of methyl mercury dicyanide

Fishable concentrations of fishes and crustaceans in the offshore and deep sea areas of the Indian Exclusive Economic Zone based on observations made onboard FORV Sagar Sampada

Bottom trawling data of FORV Sagar Sampada pertaining to a total of 350 fishing hauls with a duration of 330 effective trawling hours for depths beyond 40 m was utilized in the present study. Abundance of selected fishery resources such as threadfin bream, bull's eye, drift fish, lizard fish, ribbon fish, cat fish, barracudas, mackerel, deep sea prawns and deep sea lobster in the offshore and deep sea waters of the Indian EEZ in space and time is indicated

Effect of weight of otter boards on the horizontal opening of trawl nets

The paper gives briefly the experiments carried out to determine the optimum weight of otter board that should be used for a trawl gear for better efficiency

Generalized Mittag-Leffler Distributions and Processes for Applications in Astrophysics and Time Series Modeling

Geometric generalized Mittag-Leffler distributions having the Laplace transform $\frac{1}{1+\beta\log(1+t^\alpha)},00$ is introduced and its properties are discussed. Autoregressive processes with Mittag-Leffler and geometric generalized Mittag-Leffler marginal distributions are developed. Haubold and Mathai (2000) derived a closed form representation of the fractional kinetic equation and thermonuclear function in terms of Mittag-Leffler function. Saxena et al (2002, 2004a,b) extended the result and derived the solutions of a number of fractional kinetic equations in terms of generalized Mittag-Leffler functions. These results are useful in explaining various fundamental laws of physics. Here we develop first-order autoregressive time series models and the properties are explored. The results have applications in various areas like astrophysics, space sciences, meteorology, financial modeling and reliability modeling.Comment: 12 pages, LaTe