scholarly journals Wybrane zagadnienia dotyczące budowy tuneli z wykorzystaniem zmechanizowanych tarcz zawiesinowych

2019 ◽  
Vol 28 (3) ◽  
pp. 488-499
Author(s):  
Krzysztof Michalczuk ◽  
Mirosław Lipiński ◽  
Małgorzata Wdowska
Keyword(s):  
Shear Strength ◽  
Tunnel Boring Machine ◽  
Coarse Grained ◽  
Geotechnical Parameters ◽  
Soil Layers ◽  
Fine Grained ◽  
Tunnel Boring ◽  
A Site ◽  
Slurry Shield

The major criteria which determine selection of tunneling technology with use of tunnel boring machine (TBM) technique concern geotechnical an hydrogeological conditions of a site. When subsoil strata does not consist of rock the soils are group in two categories, i.e. coarse grained and fine grained soils. Determination of geotechnical parameters pertinent to the problem of tunneling requires individual approach in each case. In case of slurry shield technique, calculations of pressure required for face support should account for real loading conditions. In particular, with respect to shear strength, drainage conditions should be properly accounted for. Thus determined shear strength should be assigned to properly distinguished soil layers. The proper division of soil strata into soil layers is also discussed in the paper.

scholarly journals Multi-city modeling of epidemics using spatial networks: Application to 2019-nCov (COVID-19) coronavirus in India

2020 ◽  
Author(s):  
Bhalchandra S. Pujari ◽  
Snehal Shekatkar
Keyword(s):  
Hybrid Approach ◽  
Coarse Grained ◽  
Spatial Networks ◽  
Computationally Efficient ◽  
Transport Networks ◽  
Epidemiological Modeling ◽  
Fine Grained ◽  
City Modeling ◽  
Coupling Parameters

The ongoing pandemic of 2019-nCov (COVID-19) coronavirus has made reliable epidemiological modeling an urgent necessity. Unfortunately, most of the existing models are either too fine-grained to be efficient or too coarse-grained to be reliable. Here we propose a computationally efficient hybrid approach that uses SIR model for individual cities which are in turn coupled via empirical transportation networks that facilitate migration among them. The treatment presented here differs from existing models in two crucial ways: first, self-consistent determination of coupling parameters so as to maintain the populations of individual cities, and second, the incorporation of distance dependent temporal delays in migration. We apply our model to Indian aviation as well as railway networks taking into account populations of more than 300 cities. Our results project that through the domestic transportation, the significant population is poised to be exposed within 90 days of the onset of epidemic. Thus, serious supervision of domestic transport networks is warranted even after restricting international migration.

Determination of shear strength properties of coarse-grained materials for stone column

ce/papers ◽  
2018 ◽  
Vol 2 (2-3) ◽  
pp. 791-796
Author(s):  
Monika SULOVSKA ◽  
Jakub STACHO
Keyword(s):  
Shear Strength ◽  
Strength Properties ◽  
Coarse Grained ◽  
Stone Column

scholarly journals Significance of Fines in Hot Mix Asphalt Synthesis

2017 ◽  
Vol 6 (1) ◽  
pp. 30-42
Author(s):  
Elvira Kalaitzaki ◽  
George Kollaros ◽  
Antonia Athanasopoulou
Keyword(s):  
Fly Ash ◽  
Hot Mix Asphalt ◽  
Coarse Grained ◽  
Mineral Filler ◽  
Fine Grained ◽  
Particle Contact ◽  
A Value ◽  
Load Carrying ◽  
And Performance

Abstract According to their size, aggregates are classified in coarse grained, fine grained, and fines. The determination of fines content in aggregate materials is very simple and is performed through the aggregate washing during the sieving procedure to define the gradation curve. The very fine material consists of grains having a size lower than 63 μm. The presence of fines directly influences the composition and performance of concrete and asphalt mixtures (e.g. asphalt content, elasticity, fracture). The strength and load carrying capacity of hot mix asphalt (HMA) results from the aggregate framework created through particle-particle contact and interlock. Fines or mineral filler have a role in HMA. The coarse aggregate framework is filled by the sand-sized material and finally by the mineral filler. At some point, the smallest particles lose contact becoming suspended in the binder not having the particle-particle contact that is created by the larger particles. The overall effect of mineral filler in hot mix asphalt specimens has been investigated through a series of laboratory tests. It is clear that a behaviour influenced by the adherence of fines to asphalt film has been developed. The optimum bitumen content requirement in case of stone filler is almost the same as that for fly ash. It has been found that the percentage of fly ash filler is crucial if it exceeds approximately a value of 4%.

scholarly journals A Case Study on TBM Cutterhead Temperature Monitoring and Mud Cake Formation Discrimination Method

2021 ◽  
Author(s):  
Jie Fu ◽  
Yimin Xia ◽  
Hao Lan ◽  
Dun Wu ◽  
Laikuang lin
Keyword(s):  
Temperature Variation ◽  
Tunnel Boring Machine ◽  
Soil Disturbance ◽  
Tunnel Boring ◽  
Mud Cake ◽  
Cake Formation ◽  
Slurry Shield ◽  
Construction Efficiency ◽  
Discrimination Method

Abstract The mud cake is easily formed during the tunnel boring machine (TBM) excavation in clay soils or rocks containing clay minerals. Mud cake will lead to soil disturbance, clogging cutterhead and even affect the construction efficiency and personnel safety. In this study, a mud cake formation discrimination method based on cutterhead temperature was proposed. An online monitoring system was designed and installed on the slurry shield TBM. The results show that: (a) the cutterhead temperature data can be reliably detected and transmitted by the system; (b) in a tunneling ring, the temperature at some positions of the cutterhead will increase first and then decrease; (c) during the field test, the temperature variation is around 2.5℃ under the normal condition, but the temperature variation will increase more than 50℃ due to the mud cake or geological change; (d) compared with the cooling rate, mud cake formation can be accurately discriminated.

scholarly journals Prediction of four-days Soaked California Bearing Ratio (CBR) Values from Soil Index Properties

2021 ◽  
Vol 40 (1) ◽  
pp. 28-38
Author(s):  
Pascal Ambrose ◽  
Siya Rimoy
Keyword(s):  
Specific Gravity ◽  
California Bearing Ratio ◽  
Coarse Grained ◽  
Dry Density ◽  
Index Properties ◽  
Maximum Dry Density ◽  
Fine Grained ◽  
Careful Preparation ◽  
Cbr Test

California Bearing Ratio (CBR) laboratory testing is the conventional method for determining soaked strengths of pavement subgrades. The test requires careful preparation of soil samples followed by four days of water soaking before penetrating the samples using a standard plunger at prescribed rates to set depths. When the number of samples becomes large the determination of soaked CBR values becomes cumbersome as the test is laborious and time consuming. This study aimed at establishing an alternative way of determining soaked CBR by developing a model that would be used for estimating soaked CBR of fine- and coarse- grained soils without performing the CBR test. This has been achieved by correlating CBR values compacted at 95% Maximum Dry Density (MDD) with the soil index properties. The results show that soaked CBR values of fine-grained soils significantly correlate with specific gravity of soil (GS), Plasticity index (PI) and the grading modulus (GM) of the soil that yields a degree of determination of R2 = 0.91 and for coarse grained (A-2 type) soil, the soaked CBR values significantly correlate with specific gravity of soil and percentage of fines passing 0.075mm sieve size that yields a degree of determination of R2= 0.94.

Variability of undrained shear strength cu within one organic soli layer

2017 ◽  
Vol 32 (1) ◽  
pp. 8-13
Author(s):  
Krzysztof Załęski ◽  
Patryk Juszkiewicz ◽  
Paweł Szypulski
Keyword(s):  
Shear Strength ◽  
Laboratory Tests ◽  
Organic Soil ◽  
Undrained Shear Strength ◽  
Test Results ◽  
Geotechnical Parameters ◽  
Soil Layers ◽  
Undisturbed Samples ◽  
Strength Tests ◽  
Undrained Shear

For the purpose of this article a program of geotechnical laboratory tests was performed on organic soil (mud) samples from one geological layer. All undisturbed samples were taken within the same excavation in square grid with a side about 30 cm. Differences between specimen parameters were found both at basic test results and at shear strength tests results. Based on all performed tests authors suggest carefulness in assuming geotechnical parameters of organic soil layers because of theirs spatial variability even in very close vicinity.

scholarly journals Toward a Lockean Unification of Formal and Traditional Epistemology

Episteme ◽  
2020 ◽  
pp. 1-19
Author(s):  
Matthew Brandon Lee ◽  
Paul Silva
Keyword(s):  
Coarse Grained ◽  
High Confidence ◽  
Fine Grained ◽  
Traditional Epistemology ◽  
Identity Thesis ◽  
Rational Confidence ◽  
Carry Over

Abstract A Lockean metaphysics of belief that understands outright belief as a determinable with degrees of confidence as determinates is supposed to effect a unification of traditional coarse-grained epistemology of belief with fine-grained epistemology of confidence. But determination of belief by confidence would not by itself yield the result that norms for confidence carry over to norms for outright belief unless belief and high confidence are token identical. We argue that this token-identity thesis is incompatible with the neglected phenomenon of “mistuned knowledge” – knowledge in the absence of rational confidence. We show how partial epistemological unification can be secured, even without token identity, given determination of outright belief by degrees of confidence. Finally, we suggest a direction for the pursuit of thoroughgoing epistemological unification.

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