scholarly journals Prior Assessment of Variability in the Geotechnical Properties of Soils for Efficient Infrastructure Management

2021 ◽  
Author(s):  
P.L. Dharamapriya ◽  
H.A.H. Jayasena
Keyword(s):  
Sri Lanka ◽  
Liquid Limit ◽  
Geotechnical Properties ◽  
Engineering Properties ◽  
Residual Soils ◽  
Swell Potential ◽  
Geotechnical Investigations ◽  
Wide Range ◽  
Dry Zone ◽  
Wet Zone

Abstract Advance assessments of variations in geotechnical properties of soils are invaluable in making a crucial judgment of geotechnical engineering projects. It could drive to reduce the number of field and laboratory tests so that efficient management design and construction of infrastructure project outputs can be achieved. In this study, we aim at assessing the geotechnical properties of residual, alluvial, marshy, coastal, and compacted soils within the wet and the dry zones of Sri Lanka. Plastic limit (PL), liquid limit (LL), shrinkage limit (SL), plasticity index (PI), liquidity index (LI), compression index (Cc), swell potential (SP), activity, natural moisture content (NMC) and SPT-N values were either extracted from reports or deduced from formulas and graphs. Wet zone marshy soils (My_W) show highest statistical means for PL (~23%), LL (~40%), PI (~16 %), SL (~20 %), LI (~ 1%), Cc (~ 0.200) and NMC (~ 35%), indicating poor engineering properties. Wet zone residual soils (Re_W) represent a wide range of direct correlations to the parent material. CH, OH, CL and SM soil groups for some My_W show high expansive, while, CL, Pt/CL, OL, SC, SM in My_W, CL, and SC in Re_W and CL in Dry Zone Alluvial Soils (Al_D) display medium expansive. The higher SPT-N values were recorded in the upper 6.00m and between 12.00-16.00m for the shell of earth dams (SED_D) in the dry zone, in contrast to Al_D soils representing higher N values for 6.00-12.00m. Except for marshy soils, no vertical variation for plasticity was observed in others. Since high to medium swell potential in the unsaturated zone is encountered within the upper 1.50m, attention should pay to the My_W. LL and PI of My_W were strongly correlated (R2 = 0.83) so that an equation PI% = -1.91 + (0.46*LL%) could be used to calculate PI. The results provide baseline geotechnical property variations for the five soils in Sri Lanka so that during planning, best-calculated assessment could be achieved which could minimize time and cost for crucial geotechnical investigations.

Review of the genus Cnemaspis Strauch, 1887 (Sauria: Gekkonidae) in Sri Lanka with the description of five new species

Zootaxa ◽  
2007 ◽  
Vol 1490 (1) ◽  
pp. 1-63 ◽  
Author(s):  
L. J.MENDIS WICKRAMASINGHE ◽  
D. A.I. MUNINDRADASA
Keyword(s):  
New Species ◽  
Sri Lanka ◽  
Morphometric Analysis ◽  
Mountain Region ◽  
Geographical Isolation ◽  
Morphological Comparison ◽  
Type Series ◽  
Dry Zone ◽  
High Degree ◽  
Wet Zone

Five new species of geckos are described from Sri Lanka by morphological comparison and morphometric analysis leading to review the genus Cnemaspis in the country. The type series of these species were identified from following localities: C. alwisi and C. kumarasinghei from the intermediate zone, C. retigalensis from the dry zone, C. molligodai from the lowland wet zone and C. samanalensis from the mountain region of the wet zone in the country. The high degree of endemicity (90%) shown by Cnemaspis in Sri Lanka could be attributed to geographical isolation. In addition, the taxonomic issue of C. jerdonii scalpensis is discussed and the species C. scalpensis is errected.

scholarly journals Compressibility behaviour of remoulded, fine-grained soils and correlation with index properties

2000 ◽  
Vol 37 (3) ◽  
pp. 712-722 ◽  
Author(s):  
A Sridharan ◽  
H B Nagaraj
Keyword(s):  
Liquid Limit ◽  
Plasticity Index ◽  
Engineering Properties ◽  
Test Results ◽  
Index Properties ◽  
Initial Water ◽  
Fine Grained ◽  
Wide Range ◽  
The Relationship ◽  
Water Contents

Correlating engineering properties with index properties has assumed greater significance in the recent past in the field of geotechnical engineering. Although attempts have been made in the past to correlate compressibility with various index properties individually, all the properties affecting compressibility behaviour have not been considered together in any single study to examine which index property of the soil correlates best with compressibility behaviour, especially within a set of test results. In the present study, 10 soils covering a sufficiently wide range of liquid limit, plastic limit, and shrinkage limit were selected and conventional consolidation tests were carried out starting with their initial water contents almost equal to their respective liquid limits. The compressibility behaviour is vastly different for pairs of soils having nearly the same liquid limit, but different plasticity characteristics. The relationship between void ratio and consolidation pressure is more closely related to the shrinkage index (shrinkage index = liquid limit - shrinkage limit) than to the plasticity index. Wide variations are seen with the liquid limit. For the soils investigated, the compression index relates better with the shrinkage index than with the plasticity index or liquid limit.Key words: Atterberg limits, classification, clays, compressibility, laboratory tests.

scholarly journals Geotechnical and Mineralogical Appraisal of Shale and Claystone Facies of the Maastrichtian Patti Formation, Bida Basin, Nigeria

2020 ◽  
Vol 5 (2) ◽  
Author(s):  
Olusola J Ojo ◽  
Oladele A Omotoso ◽  
Adams Agbelekale ◽  
Suraju A Adepoju ◽  
Ayodeji Awe ◽  
...  
Keyword(s):  
Particle Size ◽  
Civil Engineering ◽  
Construction Material ◽  
Liquid Limit ◽  
Geotechnical Properties ◽  
Atterberg Limits ◽  
Minor Amount ◽  
Low Permeability ◽  
High Plasticity ◽  
Swell Potential

The need for construction materials in the rapidly developing areas around Federal Capital Territory, Abuja, Nigeria cannot be overemphasized and this study was undertaken in line with this need. The study area, located about 60km from Abuja, is underlain predominantly by shales and claystones of the Patti Formation. These argillaceous rocks may offer locally sourced construction material if they meet certain specifications, however to date, there has not been a geotechnical study of these rocks. The geotechnical properties and the mineralogy of the shale and claystone were investigated to evaluate their suitability for civil engineering works. Particle size distribution, Atterberg  limits and X-ray diffraction analyses were performed on fifteen shale and claystone samples collected  from  three localities (along an approximately 25km transect) for determination of their geotechnical properties and mineralogical composition. Mineralogical data obtained show the samples are dominated by kaolinite with minor amount of montmorillonite. Quartz and minor amounts of microcline, rutile and anatase dominate the non-clay mineral fraction. Particle size data indicate high proportion of fines and they are well graded. The Atterberg limits indicate that the samples have average values of liquid limit of 51%, plastic limit of 23%, plasticity index of 29% and shrinkage limit of 13%. These indicate they are of medium compressibility, low to medium shrink/swell potential, marginal expansive rating and low permeability. High bulk specific gravity (average of 2.61) suggests the samples are inorganic and this is supported by the consistency limits values. Generally, the results indicate the shale and claystone can be useful as stabilizing materials in civil engineering works. In addition, the marginally expansive nature of the shale and claystone, low permeability and intermediate to high plasticity may make them suitable as road subgrade.Keywords— activity, Bida Basin, Gerinya, Kaolinite, plasticity, Patti Formation

scholarly journals A NEW SPECIES OF Dendrelaphis BOULENGER, 1890 (REPTILIA : COLUBRIDAE) FROM THE WET ZONE OF SRI LANKA WITH A REDESCRIPTION OF Dendrelaphis bifrenalis (BOULENGER, 1890)

2020 ◽  
Vol 9 (1) ◽  
pp. 83-102
Author(s):  
A. Dineth Danushka ◽  
A. Suneth Kanishka ◽  
A.A. Thasun Amarasinghe ◽  
Gernot Vogel ◽  
Sampath S. Seneviratne ◽  
...  
Keyword(s):  
New Species ◽  
Sri Lanka ◽  
Nadh Dehydrogenase ◽  
Morphological Differentiation ◽  
Valid Species ◽  
Nadh Dehydrogenase Subunit ◽  
Dry Zone ◽  
Two Populations ◽  
A New Species ◽  
Wet Zone

Examination of the Dendrelaphis bifrenalis populations on Sri Lanka showed that there are two populations that are morphologically different from each other. One population is distributed only in the wet zone forests (hereafter treated as wet zone population), while the other population occurs widely in the dry zone and intermediate zones (hereafter dry zone population). The type series of D. bifrenalis consist of 3 specimens from which the specimen representing the dry zone population was chosen as lectotype, and the wet zone population is described here as a new species. It clearly differs from D. bifrenalis by having a shorter snout, orbit diameter 103–114% of eye–nostril length (vs 77–95%), and larger eye, orbit diameter 21–23% of head length (vs 17–20%). Furthermore it differs by having a temporal stripe stopping just beyond the neck (vs continues behind neck), the absence of black transverse dorsolateral bars on the anterior 1/4th of body (vs prominent), a narrow and pointed snout (vs broad and flat), a divided nasal (vs single), and a ventrolateral stripe continuing up to the tail (vs stopping at the level of the anal plate). This morphological differentiation is supported by the divergence in the mitochondrial NADH dehydrogenase subunit 4 (ND4) region separating clearly with the divergence of 1.70±0.35%. Also, here we resurrect D. effrenis (Werner, 1909) as a valid species, and D. sinharajensis as a junior synonym of it. The holotype of D. sinharajensis was chosen as the neotype of D. effrenis to stabilize nomenclature, and to make it an objective synonym. The third and fourth known specimens of this rare species are reported. A key of the species of the genus Dendrelaphis in Sri Lanka is provided.

Geological and soil engineering properties of shallow landslides occurring in the Kutupalong Rohingya Camp in Cox’s Bazar, Bangladesh

Landslides ◽  
2022 ◽  
Author(s):  
A. S. M. Maksud Kamal ◽  
Farhad Hossain ◽  
Md. Zillur Rahman ◽  
Bayes Ahmed ◽  
Peter Sammonds
Keyword(s):  
Shear Strength ◽  
Bulk Density ◽  
Mineralogical Composition ◽  
Fine Sand ◽  
Liquid Limit ◽  
Engineering Properties ◽  
Anthropogenic Factors ◽  
Residual Soil ◽  
Geological Condition ◽  
Residual Soils

AbstractThe Forcibly Displaced Myanmar Nationals (FDMN), historically known as ‘Rohingya’ who fled the 2017 ethnic atrocities and genocide in the Northern Rakhine State of Myanmar, took shelter in Cox’s Bazar District of Bangladesh. The camp network, known as Kutupalong Rohingya Camp (KRC), is situated in the tectonically active tertiary hilly terrain. The KRC has been experiencing hydrometeorological hazards, where landslides are frequent. This study investigated the slopes’ geological condition, engineering properties and human interventions, which influence the landslides. The exposed slopes were relatively high (> 10 m) and steep ranging from 40° to 60° that have numerous polygonal tension cracks and fissures. From the geological and geotechnical aspects, there are three successive units of slope materials: (1) residual soils of sandy silt with clay, (2) highly weathered silty sandstones and (3) shale/clay with silt and fine sand intercalations at the bottom of the slopes. Field observations revealed that most slope failures occurred in the residual soil and weathered silty sandstone units. The residual soils have a bulk density of 1.49–1.97 g/cm3, a liquid limit of 25–48%, a plasticity index of 5–16% and an undrained shear strength of 23–46 kPa. The silty sandstones have a bulk density of 1.44–1.94 g/cm3, an internal friction angle of 34°–40° and a cohesion of 0.5–13 kPa. The mineralogical composition determined by the X-ray diffraction shows low clay mineral content, which does not affect landslides. However, the slope geometry, low shear strength with strain softening properties and torrential rainfall accompanied by anthropogenic factors cause numerous landslides every year. This study will help take proper mitigation and preparedness measures for slope protection in the KRC area and surroundings.

scholarly journals Comparison of trophic structure of fish assemblages in two tropical streams in Sri Lanka: A seasonal dry-zone stream and a perennial wet-zone stream

2019 ◽  
Vol 104 (3-4) ◽  
pp. 80-93
Author(s):  
Wasantha S. Weliange ◽  
Upali S. Amarasinghe ◽  
Jacobus Vijverberg ◽  
Maria Leichtfried ◽  
Leopold Füreder
Keyword(s):  
Sri Lanka ◽  
Trophic Structure ◽  
Fish Assemblages ◽  
Tropical Streams ◽  
Dry Zone ◽  
Wet Zone

scholarly journals Mineral Content of Forages in Coconut Triangle, Wet Zone and Dry Zone Dairy Production Regions, During South-West Monsoon in Sri Lanka

2021 ◽  
Vol 3 (2) ◽  
pp. 20
Author(s):  
K. D. C. Pamalka ◽  
M. A. L. S. S. Munasinghe ◽  
W. M. P. B. Weerasinghe ◽  
W. A. D. V. Weerathilake
Keyword(s):  
Sri Lanka ◽  
Mineral Content ◽  
Dairy Production ◽  
South West ◽  
South West Monsoon ◽  
Dry Zone ◽  
West Monsoon ◽  
Wet Zone

scholarly journals Distribution of leptospirosis patients in Sri Lanka: a retrospective study

2017 ◽  
Vol 4 (4) ◽  
pp. 894
Author(s):  
Nimantha Karunathilaka ◽  
Kithsiri Jayasekara ◽  
Ishara Chathurangani ◽  
Ranga Thudugala ◽  
Athige Rajith Silva ◽  
...  
Keyword(s):  
Retrospective Study ◽  
Sri Lanka ◽  
Environmental Conditions ◽  
Water Discharge ◽  
Annual Rainfall ◽  
Tropical Country ◽  
Factors Affecting ◽  
Dry Zone ◽  
Annual Water Discharge ◽  
Wet Zone

Background: Leptospirosis [LP] is zoonotic diseases and one of the main communicable diseases in Sri Lanka [SL]. SL is a tropical country in the Indian Ocean with favorable environmental and geographical conditions for dispersion of the LP infection. The aim of the study was to determine the pattern of distribution with possible environmental conditions/factors contributing to the LP in SL.Methods: The study was carried out as retrospective study from 2009-14 throughout the all 25 administrative districts in SL.Results: The multiple regression was performed to investigate any associations between the prevalence of LP and independent variable parameters namely, annual rainfall, average humidity, area of paddy lands and annual flood data. The results revealed that factors affecting prevalence of the LP in Sri Lanka can’t be investigated in toto. Seasonal analysis is needed in the wet and dry zones corresponding to the main Yala and Maha agricultural seasons. Annual rainfall is mainly associated with the prevalence of LP in the wet zone while agricultural environment associated with the prevalence of LP in the dry zone (p<0.05). Furthermore, geographical distribution, high annual water discharge and low precipitation of the river water provides favorable environment for dispersion of LP in the wet zone whilst large reservoirs with highly functioning cascades correlated in the dry zone in SL.Conclusions: It is concluded that pattern of distribution with possible environmental conditions/factors contributing to the LP in SL is vary in the wet and dry zones. 

scholarly journals Effect of Calcium Chloride on Geotechnical Properties of Black Cotton Soil Ramya

2018 ◽  
Vol 2 (1) ◽  
Keyword(s):  
Calcium Chloride ◽  
Liquid Limit ◽  
Geotechnical Properties ◽  
Engineering Properties ◽  
Black Cotton Soil ◽  
Dry Density ◽  
Unconfined Compression ◽  
Maximum Dry Density ◽  
Treated Soil ◽  
Curing Period

The objective of the present study was to understand the effect of calcium chloride on geotechnical properties of black cotton soil. Black cotton soil collected from Siraguppa taluk, Bellary. It was subjected to various concentrations of calcium chloride viz. 0.1 N, 0.5 N, 1.0 N, 2.0 N and 4.0 N. Attempt was made to understand the effect of calcium chloride on index properties and engineering properties of black cotton soil. It was observed that the values of liquid limit, plastic limit and plasticity index of the soil treated with calcium chloride was decreasing with increase in concentration. Further the treated soil was investigated for compaction test. It was observed that the maximum dry density of the soil was increasing at higher concentrations. However, no remarkable changes were observed in the values of optimum moisture content with increase in concentration of calcium chloride. The laboratory investigation was made to obtain the unconfined compression strength (UCS) of treated soil. The soil was cured for 1 day, 7, 14 and 28 days. It was observed that the values of UCS were increasing with increase in concentration at any curing period. The soil was further tested to obtain the effect of calcium chloride on permeability of treated soil. It was observed that the permeability is increasing with increase in concentrations of 0 N, 0.5 N, and 4.0 N.

scholarly journals First record of the Woolly-necked Stork Ciconia episcopus Boddaert, 1783 (Aves: Ciconiiformes: Ciconiidae) breeding in the lowland wet zone of Sri Lanka

2017 ◽  
Vol 9 (1) ◽  
pp. 9738 ◽  
Author(s):  
Hemachandra Kularatne ◽  
Susantha Udagedara
Keyword(s):  
Sri Lanka ◽  
Bird Species ◽  
Heavy Rain ◽  
First Record ◽  
Nesting Behavior ◽  
Breeding Cycle ◽  
Dry Zone ◽  
First Time ◽  
Resident Bird ◽  
Wet Zone

The Woolly-necked Stork Ciconia episcopus is a resident bird species commonly found breeding in the dry lowlands of Sri Lanka, preferably nesting in remote areas with minimal disturbance, although the breeding and nesting behavior has not yet been adequately documented.  Here we report its nesting behavior, for the first time in lowland wet zone Sri Lanka, from Thalagolla, Beddawela in Kegalle District.  Although its usual breeding season is in the dry zone from February to March with a second breeding cycle from November to early January, here we report breeding in the lowland wet zone from July–October in 2013–2014.  Further, it was interesting to note presumably the same couple of birds used the same nest in 2014 with minimum renovation.  In 2015 the nest had disintegrated and fallen due to continuous heavy rain and there have been no records till June 2016.  Breeding was again recorded from June–September in 2016 with a new nest in a different platform of twigs in the same tree.  

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