Impedances of embedded rigid strip foundations

This paper is concerned with the dynamic response of rigid strip foundations of arbitrary geometry embedded in a homogeneous elastic half-space. The embedded rigid foundation is modelled by an equivalent domain in a uniform half-space which is subjected to an appropriate body force field. The components of the impedance matrix are determined through the solution of a linear simultaneous equation system which is established by invoking rigid body displacements of discrete locations within the equivalent domain and appropriate equilibrium consideration. It is found that high numerical efficiency and flexibility can be achieved using the body force model when compared to boundary integral formulations through the selection of appropriate displacement influence functions and a ‘parent domain’ in the analysis. Numerical results are presented to illustrate the influence of the embedment ratio, frequency of excitation, foundation geometry and Poisson's ratio on the vertical, horizontal, rocking and coupled impedances of a single embedded foundation. The effect on the impedance due to the presence of an adjacent embedment is investigated for various distances between foundations and embedment ratios.     

Fuzzy information processing in seismic hazard analysis and decision making

This paper describes a methodology to incorporate vague information, based upon heuristic knowledge and expertise, into the conventional probabilistic approach for the seismic hazard analysis.

The interval analysis method is introduced to process interval information with interpretation from Dempster and Shafer's evidence theory. The Vertex Method is discussed to handle fuzzy information which is a generalization of interval information.

These methods, along with the current approach of seismic hazard analysis, are used to assess the seismic hazard for the San Francisco Bay Area in California and to provide information for deciding strengthening policy of existing buildings.     

Arsenic-contaminated groundwater from parts of Damodar fan-delta and west of Bhagirathi River,West Bengal,India: influence of fluvial geomorphology and Quaternary morphostratigraphy

Arsenic contamination in groundwater affecting West Bengal (India) and Bangladesh is a serious environmental problem. Contamination is extensive in the low-lying areas of Bhagirathi–Ganga delta, located mainly to the east of the Bhagirathi River. A few isolated As-contaminated areas occur west of the Bhagirathi River and over the lower parts of the Damodar river fan-delta. The Damodar being a Peninsular Indian river, the arsenic problem is not restricted to Himalayan rivers alone. Arsenic contamination in the Bengal Delta is confined to the Holocene Younger Delta Plain and the alluvium that was deposited around 10,000–7,000 years bp, under combined influence of the Holocene sea-level rise and rapid erosion in the Himalaya. Further, contaminated areas are often located close to distribution of abandoned or existing channels, swamps, which are areas of surface water and biomass accumulation. Extensive extraction of groundwater mainly from shallow aquifers cause recharge from nearby surface water bodies. Infiltration of recharge water enriched in dissolved organic matter derived either from recently accumulated biomass and/or from sediment organic matter enhanced reductive dissolution of hydrated iron oxide that are present mainly as sediment grain coatings in the aquifers enhancing release of sorbed arsenic to groundwater.     

Petrology of calc-alkaline/adakitic basement hosting A-type Neoproterozoic granites of the Malani igneous suite in Nagar Parkar,SE Sindh,Pakistan

The Nagar Parkar area contains three distinct groups of rocks, from oldest to youngest, (1) basement rocks ranging in composition from mafic to (quartz)diorite, tonalite, granite, and younger granodiorite, (2) granite plutons similar in general features to those of the Malani Igneous Suite of Rajasthan, and (3) abundant mafic, felsic and rhyolitic dykes. The basement rocks show strong brittle and local plastic deformation, and epidote amphibolite/upper greenschist facies metamorphic overprint. The chemistry of the basement rocks contrasts the commonly agreed within plate A-type character of the Neoproterozoic granites (group 2) that are emplaced into them. The basement rock association is calc-alkaline; the granodiorite displays the compositional characteristics of adakites, whereas the tonalite has intermediate composition between typical adakite and classical island arc rocks. This paper presents detailed petrography of the basement rocks and compares their geochemistry with those of the group 2 granites as well as with rocks from other tectonic environments. It is proposed that the Nagar Parkar basement is part of a 900–840 Ma magmatic arc that was deformed before it was intruded 800–700 Ma ago by the A-type continental granitic rocks followed by mafic to felsic dykes.     

Distribution of gold in different size fractions of stream sediments as a guide to bedrock gold mineralisation along the Shyok Suture Zone and adjacent areas of the Kohistan Island Arc,Pakistan

Arabian Journal of Geosciences - This paper describes a new exploration methodology using stream sediments in remote and glaciated regions of northern Pakistan. Gold concentrations in 268 samples...     

Flood exposure and social vulnerability in the United States

Natural Hazards - Human exposure to floods continues to increase, driven by changes in hydrology and land use. Adverse impacts amplify for socially vulnerable populations, who disproportionately...     

Knowledge mapping analysis of research progress and frontiers in integrated disaster risk management in a changing climate

Natural Hazards - Integrated disaster risk management in a changing climate is a key concern for disaster reduction and global sustainable development now and in the future. This study conducted...     

Numerical Analysis of Himalayan Rock Tunnels under Static and Blast Loading

Geotechnical and Geological Engineering - Tunnels have been the necessary element of the modern construction industry. Due to their importance for the infrastructural and economic point of view,...     

A comprehensive and quantitative assessment of Raunthi Gad flash flood,Rishi Ganga catchment,central Himalaya,Uttarakhand, India

Natural Hazards - Drought severity is increasing in Southern Africa which is affecting rain-fed agriculture, the main source of livelihood in most countries in this region. The study assessed the...