scholarly journals A study on soil-geotextile interaction using gradient ratio tests

2019 ◽  
Vol 28 (2) ◽  
pp. 235-243
Author(s):  
Anna Miszkowska
Keyword(s):  
Laboratory Tests ◽  
Drainage System ◽  
Ratio Test ◽  
Test Device ◽  
Fine Content ◽  
Gradient Ratio ◽  
Nonwoven Geotextile

Nonwoven geotextile have been widely used for filtration. In this paper, the clogging potential for a soil-geotextile system were assessed using laboratory tests. An ASTM modified gradient ratio test device was used to determine gradient ratio as well as soil-gradient ratio. One type of nonwoven geotextile and soil were used to simulate the conditions in drainage system. The obtained results indicate that the gradient ratio and soil-gradient ratio increases with time because of clogging mechanism. However, the tested geotextile can be used as fi lter for soil with fine content of 20%.

A Modified Gradient Ratio Test Device

2009 ◽  
pp. 100-100-13 ◽  
Author(s):  
RJ Fannin ◽  
YP Vaid ◽  
EM Palmeira ◽  
YC Shi
Keyword(s):  
Ratio Test ◽  
Test Device ◽  
Gradient Ratio

A Cyclic Gradient Ratio Test Device

2002 ◽  
Vol 25 (3) ◽  
pp. 9921
Author(s):  
L David Suits ◽  
TC Sheahan ◽  
A Hameiri ◽  
RJ Fannin
Keyword(s):  
Ratio Test ◽  
Test Device ◽  
Gradient Ratio

scholarly journals Effect of the Number of Constrictions on the Filtration Behaviour of a Soil-Geotextile System

2020 ◽  
Vol 28 (1(139)) ◽  
pp. 87-92
Author(s):  
Anna Miszkowska ◽  
Anna Miszkowska ◽  
Eugeniusz Koda ◽  
Zygmunt Krzywosz
Keyword(s):  
Selection Criteria ◽  
Fine Particles ◽  
Filter Design ◽  
Ratio Test ◽  
Flow Through ◽  
Gradient Ratio ◽  
Geotextile Filters ◽  
Nonwoven Geotextile ◽  
Geotextile Filter ◽  
Base Soil

Nonwoven geotextile filters have been used in geo-environmental engineering for decades to prevent the movement of base soil fine particles, allowing adequate seepage to flow through the geotextile plane. Most of the design criteria developed for nonwoven geotextiles are based only on the comparison between their characteristic opening size and the indicative diameter of the soil to be filtered. In the meantime, the nonwoven geotextile fibrous structure has an influence on the filtration of the soil-geotextile system. In this paper the numbers of constrictions of nonwoven geotextile samples were determined to verify the existence of a correlation between the geotextile structure and the filtration behaviour of soil-geotextile systems. The compatibility between an internally unstable soil and a nonwoven geotextile filter was evaluated using the gradient ratio test. The results obtained can also be the basis for modifying the geotextile filter design and selection criteria.

Study on the Sprayed Concrete with Iron Tailings

2011 ◽  
Vol 347-353 ◽  
pp. 1939-1943 ◽  
Author(s):  
Wen Yong Liu ◽  
Xiao Liang Xu ◽  
Yong Ye An
Keyword(s):  
Emission Reduction ◽  
Laboratory Tests ◽  
Iron Ore ◽  
New Technology ◽  
Ratio Test ◽  
Natural Sand ◽  
Sprayed Concrete ◽  
Key Technology ◽  
Iron Ore Mine ◽  
The Subject

This essay is the subject of national eleventh five support schemes: The analysis of key technology on emission reduction and comprehension utilization of solid waste from large iron ore mine (Number:2008BAB32B14). The purpose of this test is to replace natural sand with the same amount of iron tailings and find a new technology method to utilize iron tailings. Based on theory of the preparation of sprayed concrete, this experiment made ratio test with 20%, 40%, 60%, 80% and 100% iron tailings content, and finally achieved the result which met the engineering required, after multiple batches of laboratory tests. By studying mechanical properties of sprayed concrete mixing different proportions of iron tailings, the optimal ratio of iron tailings to replace nature sand have been gotten. The result indicates that with 20% iron tailings to replace nature sand, the performance of sprayed concrete is the best.

scholarly journals OpenSAFELY NHS Service Restoration Observatory 1: primary care clinical activity in England during the first wave of COVID-19

2021 ◽  
pp. BJGP.2021.0380
Author(s):  
Helen J Curtis ◽  
Brian MacKenna ◽  
Richard Croker ◽  
Peter Inglesby ◽  
Alex J Walker ◽  
...  
Keyword(s):  
Primary Care ◽  
General Practice ◽  
Respiratory Disease ◽  
Laboratory Tests ◽  
Respiratory Infections ◽  
Seasonal Pattern ◽  
Substantial Reduction ◽  
Chronic Obstructive ◽  
Clinical Activity ◽  
Ratio Test

BackgroundThe COVID-19 pandemic has disrupted healthcare activity. The NHS stopped non-urgent work in March 2020, later recommending services be restored to near-normal levels before winter where possible.AimTo describe the volume and variation of coded clinical activity in general practice, taking respiratory disease and laboratory procedures as examples.Design and settingWorking on behalf of NHS England, a cohort study was conducted of 23.8 million patient records in general practice, in situ using OpenSAFELY.MethodActivity using Clinical Terms Version 3 codes and keyword searches from January 2019 to September 2020 are described.ResultsActivity recorded in general practice declined during the pandemic, but largely recovered by September. There was a large drop in coded activity for laboratory tests, with broad recovery to pre-pandemic levels by September. One exception was the international normalised ratio test, with a smaller reduction (median tests per 1000 patients in 2020: February 8.0; April 6.2; September 6.9). The pattern of recording for respiratory symptoms was less affected, following an expected seasonal pattern and classified as ‘no change’. Respiratory infections exhibited a sustained drop, not returning to pre-pandemic levels by September. Asthma reviews experienced a small drop but recovered, whereas chronic obstructive pulmonary disease reviews remained below baseline.ConclusionAn open-source software framework was delivered to describe trends and variation in clinical activity across an unprecedented scale of primary care data. The COVD-19 pandemic led to a substantial change in healthcare activity. Most laboratory tests showed substantial reduction, largely recovering to near-normal levels by September, with some important tests less affected and recording of respiratory disease codes was mixed.

Performance of Nonwoven Geotextile as a Filter at Road Shoulder

2013 ◽  
Vol 701 ◽  
pp. 333-336
Author(s):  
Shamshinar binti Salehuddin ◽  
Nur Liza Rahim ◽  
Norlia Mohamad Ibrahim ◽  
Mohd Amirul Hafiz Bin Ilias
Keyword(s):  
Positive Impact ◽  
Drainage System ◽  
Suspended Solid ◽  
Small Scale ◽  
Minimum Thickness ◽  
The Road ◽  
Before And After ◽  
The Difference ◽  
Water Base ◽  
Nonwoven Geotextile

Geotextile is one of material in engineering field. In this research, nonwoven geotextile is used at road shoulder to flow clean water to the drainage system since it can act as a filter. The purpose of this research are to determine the ability of nonwoven geotextile as filter media and identify the quality of the filtered water before and after placing the nonwoven geotextile. Therefore, the road shoulder is designed to show the filtering process. Based on the JKR Manual On Pavement Design, a minimum thickness for soil and aggregate is 100 mm and each layer is compacted. However, the actual thickness is not being used because it is only to show the ability of nonwoven geotextile in filtering process and its consequence of using it. Two small scale models are created, first is with nonwoven geotextile and another one is without geotextile which aims to show the difference. Tank size 350 x 200 x 240 mm is used for placing material same as road shoulder such as nonwoven geotextile, sand, soil, and aggregates which form in three layers. Water was poured in the road shoulder model. Then the water sample flow out from the tank was tested in terms of level of turbidity and suspended solids contained in the water. Base on the results, it shows that the use of nonwoven geotextile can reduce almost 100% of suspended solid and turbidity of the water from flow into drainage system. As conclusion, the use of nonwoven geotextile at road shoulder can contribute positive impact to reduce the level of water pollution.

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