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Collapsible soils are problematic by nature. They undergo collapse or sudden settlement or subsidence under a given stress when their water content is increased. Collapse is characterised by collapse potential expressed as ΔH/H x 100, where ΔH is collapse compression. The amount of stress applied and the water content at the time of collapse govern the amount of collapse. In other words, collapse potential depends upon the amount of stress and the water content. Loess and other wind-blown silts are examples of collapsible soils. This paper presents a parametric study on the collapse behaviour of a lateritic soil. Remoulded specimens of a lateritic soil passing through a 425 µm sieve were compacted in 1-D consolidometer or oedometer at a density of 13 kN/m3 for studying collapse under varied initial moisture contents and initial surcharge pressures. Collapse compression of the samples was induced by saturating the specimens with water contents corresponding to 100% degree of saturation. After collapse occurred, the 1-D consolidation tests were continued up to an applied stress of 160 kPa. Collapse behaviour was studied for the applied initial pressures (σi) of 10, 20 and 40 kPa and for the initial water contents (wi) of 5%, 10%, 15% and 20%. Collapse compression and collapse potential decreased with increasing wi for all σi.  相似文献   
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Hydrochemical and hydrogeological studies were carried out in the groundwater of Dhaligaon refinery area, Bongaigoan district, Assam. The study revealed that the area is underlain by alluvial deposits of thickness varying from 67 to 142 meters and the groundwater occurs in unconfined alluvial formations. Transmissivity values of the formations range from 2100 to 3800 m2/day. The effluents from the refinery are disposed off into a natural drain, “Tunia nala”, which contaminates the groundwater. The effluents contain constituents like phenol, nitrite, sulphide, iron etc, which subsequently seep into the dug well zone, but the phenol concentrations get naturally attenuated during the contaminant transport to the depths below. The probable reasons leading to natural attenuation of phenol as per in-situ hydrogeological and environmental conditions have been discussed.  相似文献   
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Fluoride (F?) is essential for normal bone growth, but higher concentration in the drinking water causes health problems which are reported in many states of India. Andhra Pradesh is one of the states which suffer from excess fluoride in groundwater particularly in the hard rock terrain. In this context, a study was conducted in Andhra Pradesh based on chemical analysis of water samples from hydrograph net work stations (dug wells) and exploratory bore wells. The concentration of fluoride in groundwaters ranges from traces to 9.75 mg/l. The occurrence of fluoride is mostly sporadic, uneven and varies with depth. The highly affected districts include Nalgonda and Warangal in Telangana region, Prakasam in coastal region, Anantapur and Kurnool in Rayalaseema region. In certain areas of Nalgonda district, 85% of wells have fluoride more than permissible limit (> 1.5 mg/l) for drinking water. High F? is present in all the geological formations, predominantly in granitic aquifers, compared to the other formations. The average value of fluoride is high in the deeper zone (1.10 mg/L), compared to the shallow zone (0.69 mg/L). The fluoride-rich minerals present are the main sources for fluoride concentrations in groundwater. Residence time, evapotranspiration and weathering processes are some of the other supplementary factors for high fluoride concentrations in groundwater. Long-term data of hydrograph net work stations (dug wells) reveal that fluoride concentrations do not show any marked change of trend with respect to time. The concentration of fluoride is found to increase with increase of Na+and HCO 3 ? , and decrease with increase of Ca2+. Sodium bicarbonate waters are more effective in releasing fluoride from minerals into groundwater. High fluoride waters are of Na+ type. The paper presents a brief account of the study and its results.  相似文献   
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Adhvaryu  Bhargav  Mudhol  Sushmita S. 《GeoJournal》2021,87(4):485-509

Rapid urbanisation in India is a key contributor to the overstressed public infrastructure. The urban public transport system is one of the important infrastructure systems. An effective public transportation network helps the city improve its accessibility, lower carbon footprint, and enhances economic growth and societal equity. India is a relatively poor country with limited public resources. Therefore, investing in an effective urban public transport system needs a tailored approach. Such an approach would entail using public transport to guide urban development. In this context, the first step would be to measure the accessibility levels of the existing public transport network and then use the accessibility mapping outputs to better inform the urban planning process. This study explores the Public Transport Accessibility Level (PTAL) tool that measures the accessibility of the public transport system and provides a spatial visualisation using Geographic Information System. PTAL is implemented taking Hubli-Dharwad as a case study for the base year (2020) superimposed with population and employment density, and future year (2031). The outcome of the research facilitates the city planning process by guiding transportation and land-use zoning integrations, direct public transport investments, demarcation of transit-oriented development zones, parking policies, and identifying locations of affordable and low-cost housing.

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