scholarly journals Modeling of Loess Soaking Induced Impacts on a Metro Tunnel Using a Water Soaking System in Centrifuge

Geofluids ◽  
2019 ◽  
Vol 2019 ◽  
pp. 1-17 ◽  
Author(s):  
Yuwei Zhang ◽  
Xiaolin Weng ◽  
Zhanping Song ◽  
Yufeng Sun
Keyword(s):  
Mechanical Properties ◽  
Water Distribution ◽  
Full Range ◽  
Water Storage ◽  
Model Tests ◽  
Test Equipment ◽  
Collapsible Loess ◽  
Metro Tunnel ◽  
Centrifugal Model ◽  
Centrifugal Test

The collapsibility is one of the key properties for loess. Harmful impacts on the metro tunnels could be obviously subjected to the soaking collapsibility in collapsible loess. However, loess soaking cannot be effectively modeled by the existing centrifugal test equipment (CTE) due to its inherent limitations. In the present paper, a water soaking system (WSS) was improved based on the existing CTE for simulating various loess soaking conditions. The WSS was made of a water storage subsystem and a water distribution subsystem. Some tests were conducted to show the capability of the improved WSS in centrifugal model tests firstly, then it was used to carry out centrifugal model tests on a metro tunnel under full-range and half-range foundation soaking conditions with different soaking depths. The impacts of various soaking conditions on the mechanical properties of the metro tunnel were discussed in detail.

scholarly journals CARACTERIZAÇÃO DA DISTRIBUIÇÃO DA ÁGUA NO SOLO PARA IRRIGAÇÃO POR GOTEJAMENTO

Irriga ◽  
2018 ◽  
Vol 14 (4) ◽  
pp. 564-577 ◽  
Author(s):  
Leonardo Do Nascimento Lopes ◽  
Elton Martins ◽  
Bruno De Lima Santoro ◽  
Claudinei Fonseca Souza
Keyword(s):  
Water Content ◽  
Time Domain ◽  
Water Distribution ◽  
Water Storage ◽  
Time Domain Reflectometry ◽  
Wetting Front ◽  
Applied Water ◽  
Flow Rates ◽  
Abstract Knowledge ◽  
The Time Domain

CARACTERIZAÇÃO DA DISTRIBUIÇÃO DA ÁGUA NO SOLO PARA IRRIGAÇÃO POR GOTEJAMENTO  Leonardo do Nascimento Lopes1; Elton Martins2; Bruno de Lima Santoro2; Claudinei Fonseca Souza31Universidade de Taubaté, Unitau, Taubaté, SP,  [email protected] Engenharia Civil e Ambiental, Universidade de Taubaté, Taubaté, Unitau, SP 3Departamento de Recursos Naturais e Proteção Ambiental, Universidade Federal São Carlos, São Carlos, SP  1 RESUMO O conhecimento da distribuição da água no solo é de grande importância para a agricultura, uma vez que a água é um dos fatores que mais influenciam o rendimento das culturas. Existem muitas técnicas utilizadas para o monitoramento do conteúdo de água do solo, a reflectometria domínio do tempo (TDR) tem sido difundida entre os pesquisadores por apresentar várias vantagens, entre as quais a determinação em tempo real e a possibilidade de leituras automatizadas. O principal objetivo desta pesquisa foi avaliar a distribuição da água no perfil de um Latossolo Vermelho-Amarelo. Sondas de Reflectometria no domínio do Tempo (TDR) foram utilizadas para monitorar a distribuição de água no solo aplicada através de gotejadores de fluxo constante nas taxas de 2, 4 e 8 Lh-1. Considerando os resultados de diferentes perfis, observa-se um maior armazenamento da água próximo do gotejador diminuindo progressivamente para frente de molhamento. Aproximadamente, um terço da água aplicada (33%) foi armazenado na primeira camada (0-0,10 m) para todos os ensaios. Comparando diferentes taxas de aplicação, observa-se maior armazenamento de água para o gotejador de 8L h-1, com 30, 33 e 34% de água aplicada acumulada na primeira camada (0-0.10 m) para gotejadores de 2, 4 e 8L h-1, respectivamente. Os resultados sugerem que, com base no volume e frequência utilizada neste experimento, seria vantajoso aplicar pequenas quantidades de água em intervalos mais frequentes para reduzir perdas por percolação. UNITERMOS: TDR, conteúdo de água, bulbo molhado  LOPES, L. N.; MARTINS, E.; SANTORO, B. L.; SOUZA, C. F.WATER DISTRIBUTION CHARACTERIZATION IN SOIL FOR DRIP IRRIGATION   2 ABSTRACT Knowledge of water distribution in soil is of great importance to agriculture, since water is one of the factors that most influence the yield of crops. There are many techniques used to monitor soil water content. The time domain reflectometry (TDR) has been widespread among researchers because it presents several advantages, among which the determination in real time and possibility of automated readings. The main goal of this research was to evaluatethe water distribution in a profile of Red-Yellow Oxisol. Time domain reflectometry (TDR) probes were used to monitor the water distribution from drippers discharging at constant flow rates of 2, 4 and 8 Lh-1 in soil. Considering results from different profiles, we observed greater water storage near the dripper decreasing gradually towards the wetting front. About one third of the applied water (33%) was stored in the first layer (0-0.10 m) for all experiments. Comparing different dripper flow rates, we observed higher water storage for 8 L h-1, with 30, 33 and 34% of applied water accumulating in the first layer (0-0.10m) for dripper flow rates of 2, 4 and 8 L h-1, respectively. The results suggest that based on the volume and frequency used in this experiment, it would be advantageous to apply small amounts of water at more frequent intervals to reduce deep percolation losses of applied water. KEYWORDS: TDR, water content, wetted soil volume

scholarly journals Application of the Non-Contact Video Gauge on the Mechanical Properties Test for Steel Cable at Elevated Temperature

2019 ◽  
Vol 9 (8) ◽  
pp. 1670 ◽  
Author(s):  
Yong Du ◽  
Zhang-ming Gou
Keyword(s):  
Mechanical Properties ◽  
Elevated Temperature ◽  
Ambient Temperature ◽  
Strain Gauge ◽  
Complex Shape ◽  
Full Range ◽  
Steel Cable ◽  
Stress Strain ◽  
Strain Stress ◽  
Steel Cables

As the limit of traditional contact measurement, it is difficult to precisely measure the steel cables twisted by a branch of wires especially at elevated temperature. In this paper the strain-stress relationships of S355 and S690 structural steel, 1860 MPa steel cable twisted by seven wires have been measured by the strain gauge, extensometer and non-contact video gauge at ambient temperature and elevated temperature, respectively. Comparison of the stress-strain curves gotten by different measuring technology, it indicates that the non-contact video gauge can provide a more efficient and reliable database than the strain gauge as well as extensometer, especially at an elevated temperature. It is worth noting that the non-contact video gauge can capture not only the full range of stress-strain curves of steel cables, but is also efficient for the specimens with a complex shape.

Study on the Testing Auxiliary System of a Large Scale Centrifugal Shaker

2011 ◽  
Vol 368-373 ◽  
pp. 959-962
Author(s):  
Yong Zhi Wang ◽  
Xiao Ming Yuan ◽  
Rui Sun
Keyword(s):  
Data Acquisition ◽  
Large Scale ◽  
Image Acquisition ◽  
Model Tests ◽  
Auxiliary System ◽  
Basic Design ◽  
Data Acquisition Systems ◽  
Design Requirements ◽  
Centrifugal Model ◽  
And Function

By special advantages and progress of dynamic centrifugal model tests, construction and development of large scale centrifugal shakers are driven. As one subsystem of a large scale centrifugal shaker, the testing auxiliary system is used to data acquisition, image acquisition and model making. The perfect design and construction of a testing auxiliary system must give a guarantee for dynamic centrifugal model tests. This paper outlines the components and function of the testing auxiliary system of a large scale centrifugal shaker. The basic design requirements and critical techniques relevant to data acquisition systems, image acquisition systems and containers are analyzed according to the characteristics of dynamic centrifugal model tests on a large scale centrifugal shaker, meanwhile, some specific conception and design suggestions are proposed. The results can offer some references for design of the testing auxiliary system of a large scale centrifugal shaker.

J192015 Centrifugal Model Tests for Stability Evaluation of Lunar Sandbag Wall

2011 ◽  
Vol 2011 (0) ◽  
pp. _J192015-1-_J192015-5
Author(s):  
Daisuke INOUE ◽  
Yoshitaka YANAGIHARA ◽  
Hiroshi UENO ◽  
Shinichiro NISHIDA
Keyword(s):  
Model Tests ◽  
Stability Evaluation ◽  
Centrifugal Model

Determining the Area Function of Spherical Indenters for Nanoindentation.

2000 ◽  
Vol 649 ◽  
Author(s):  
Andrew J. Bushby ◽  
Nigel M. Jennett
Keyword(s):  
Mechanical Properties ◽  
Yield Point ◽  
Reference Materials ◽  
Mechanical Response ◽  
Permanent Deformation ◽  
Full Range ◽  
High Sensitivity ◽  
Powerful Technique ◽  
Test Parameters ◽  
Actual Shape

ABSTRACTNanoindentation with spherical tipped indenters provides a powerful technique for exploring surface mechanical properties through the application of Hertzian mechanics. The full range of mechanical response can be obtained from elastic, through the yield point to a range of permanent deformation. However, the successful application of the technique requires accurate calibration of the indenter tip geometry. In this paper methods based on indentation into a number of reference materials are used to characterise a range of spherical tipped indenters with nominal radii from 5 to 50 microns. A traceably calibrated metrological AFM is also used to determine the actual shape of one of the indenters. The sensitivity of each method to test parameters is discussed. Coincidence of the data from both methods validates the determined shape of the indenter and offers the opportunity to cross-correlate the calibration of both instruments with high sensitivity.

Application of Centrifugal Model Tests in the Preliminary Support of the Tunnel: A Review

2014 ◽  
Vol 1049-1050 ◽  
pp. 242-245
Author(s):  
Jun Ling Qiu ◽  
Jin Xing Lai
Keyword(s):  
Boundary Conditions ◽  
Stress Level ◽  
Future Development ◽  
Geotechnical Engineering ◽  
Model Tests ◽  
Structure Model ◽  
Related Research ◽  
Modeling Technology ◽  
Centrifugal Model ◽  
Preliminary Support

Centrifugal modeling technology has been applied to geotechnical engineering for more than half a century. It has been an important and indispensible means to simulate the geotechnical behavior because it has the same material, the similar boundary conditions and the same stress level. And it is also commonly used in tunnel-related research. Centrifugal tests of pipe-roof and small pipe grouting in tunnel were analyzed, the important effects of centrifugal tests on preliminary support of the tunnel were also emphasized. Problems often met in model tests of tunnelling were solved, such as structure model, modeling soil, preliminary support model and general programming of experiment proposal. The future development of centrifuges in tunnelling is also presented.

Use of centrifugal model testing to assess slope stability

1978 ◽  
Vol 15 (1) ◽  
pp. 14-31 ◽  
Author(s):  
A. N. Schofield
Keyword(s):  
Heat Transfer ◽  
Slope Stability ◽  
Model Tests ◽  
Material Behaviour ◽  
Total Stress ◽  
End Effects ◽  
Soil Material ◽  
Reconstituted Soil ◽  
Centrifugal Model ◽  
Small Models

Centrifugal model tests increase total stress levels in small models made of natural or reconstituted soil, and allow direct observation of repeated failures. A novel use of a basket centrifuge is described in which slopes can be tested without end effects. When a series of models at various overconsolidation ratios was tested to failure the error in the safety factor predicted by a total stress analysis increased with the overconsolidation ratio. Other centrifuges are discussed and the advantage of large machines with balanced arms and swinging carriages are explained. Soil material behaviour discussed includes heat transfer and leaching. The paper concludes with a review of the present availability of and prospects for centrifugal model tests.

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