Analysis on the Embankment Settlements Induced by Slurry Shield Under-Tunnelling

2011 ◽  
Vol 261-263 ◽  
pp. 938-942
Author(s):  
Zhong Miao Zhang ◽  
Cun Gang Lin ◽  
Shi Ming Wu
Keyword(s):  
Back Analysis ◽  
Good Control ◽  
Chamber Pressure ◽  
The West ◽  
Construction Experience ◽  
Ground Volume Loss ◽  
Fitting In ◽  
Slurry Shield ◽  
Loss Range ◽  
Settlement Monitoring

Based on field settlement monitoring data in construction of Hangzhou Qiantang River tunnel, the settlements of the embankment induced by two shields respectively were compared. The study shows that: 1.The settlements of the embankment induced by the west shield are larger, which are accounted for sustained rainfall, severe fluctuation of the chamber pressure, lack of construction experience and worse control of shield driving parameters. 2. Peck equation is applicable to settlement fitting in this case history. Trough back-analysis, the traverse tough-width parameter and ground volume loss range from 0.33 to 0.47, 0.99% to 1.57% respectively for the embankment settlements above the west tunnel, and from 0.24 to 0.34, 0.25% to 0.52% for the east tunnel. 3. Good control of shield driving parameters contributes to small disturbance to surrounding soils, thereby decreasing the induced settlements of the embankment.

The Edgerton landslides

1995 ◽  
Vol 32 (6) ◽  
pp. 989-1001 ◽  
Author(s):  
D.M. Cruden ◽  
S. Thomson ◽  
H.J. Kim ◽  
A.E. Peterson
Keyword(s):  
Key Words ◽  
Residual Strength ◽  
Upper Cretaceous ◽  
Sedimentary Rocks ◽  
Back Analysis ◽  
Rock Slide ◽  
The West ◽  
West Wall ◽  
Earth Flow ◽  
Average Precipitation

Observations over 20 years of three contiguous translational slides on the west wall of a 100 m deep valley in the Interior Plains document their evolution into advancing, composite, slow earth-flow earth-slides involving over a million cubic metres of displaced material. Colluvial deposits downslope of the apparent toes of the flows are moving. The reactivation of the abandoned slides in the Upper Cretaceous sedimentary rocks was likely triggered by years of higher than average precipitation following clearing of brush behind the crest of the slope. Back analysis is consistent with fully softened rock in the crowns of the slides and displaced materials at residual strength. Key words : landslide, rock-slide, earth-flow, earth-slide, Interior Plains.

Eating Out

2017 ◽  
pp. 97-128
Author(s):  
Anna Cottrell
Keyword(s):  
Middle Class ◽  
The Self ◽  
Ordinary People ◽  
The West ◽  
Lower Middle Class ◽  
Cultural Preferences ◽  
Working Lives ◽  
Eating Out ◽  
Work Variations ◽  
Fitting In

In Virginia Woolf’s The Years (1937), Eleanor Pargiter observes a lower-middle-class couple in a restaurant, enjoying their time off after work. Variations of this scene appear in many novels of the 1930s; the restaurants and teashops where London’s lower middle class spent their lunch breaks and evening outings became the settings in which their behaviour, their cultural preferences and even their dreams could be scrutinised. Eleanor concludes after watching the self-conscious couple that their performance is borrowed from the movies and illustrated magazines. This performance consisted of glamour and ‘nonchalance’ – modes incompatible with their working lives, but perfectly fitting in establishments that offered ordinary people atmospheres far removed from their mundane routines. Although Woolf does not identify it as such, the scene probably takes place in a Lyons Corner House – one of the four grand central London teashops that provided their patrons not only with affordable food, but also with a visual spectacle that could rival the glitter of the West End and the glamour of cinemas.

Slurry Shield Tunnelling in Clayey Soils: Typical Problems and Countermeasures

2011 ◽  
Vol 243-249 ◽  
pp. 2944-2947
Author(s):  
Zhong Miao Zhang ◽  
Cun Gang Lin ◽  
Shi Ming Wu
Keyword(s):  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Low Permeability ◽  
Clayey Soils ◽  
Excess Pore Water Pressure ◽  
Shield Tunnelling ◽  
Ground Volume Loss ◽  
Slurry Shield ◽  
Excess Pore

The distinguishing characteristics of clay are high cohesion and low permeability. For slurry shield tunnelling in clayey soils, favorable aspects are that slurry cake with low permeability can be established more easily and effectively at the excavation face thanks to clay’s high cohesion, which is advantageous for stability of excavation face, and long stand-up time of clay offers enough time for backfilling of the tail void before collapse of surrounding soils, thus lessening ground volume loss. However, some typical problems are encountered due to clay’s high cohesion and low permeability. One primary problem is the clogging of slurry pipeline, once in case of which, slurry pressure will fluctuate severely, thus inducing unstable condition at the excavation face. In extreme cases, the pipeline bursts and soils at the excavation face collapse towards the cutterhead for immediate drop of slurry pressure. Another common problem is clay’s adhesion to the cutterhead, which weakens the excavation efficiency of cutterhead and limits advance rate of the shield machine. Tunnelling will inevitably disturb surrounding soils and excess pore water pressure occurs. In clayey soils, due to clay’s low permeability, it usually takes quite a long time for the excess pore water pressure to disperse completely. The consolidation settlements associated with pore water dispersing account for a large percentage of the total settlements. Accumulated ground settlements threaten structures and pipelines nearby. For these problems encountered during slurry shield tunnelling in clayey soils, both preventive and counter measures are put forward in detail in this study. The proposed measures can be used as a reference to avoid, mitigate and deal with problems encountered during slurry shield tunnelling in clayey soils.

scholarly journals New distributional records of the Samana least gecko (Sphaerodactylus samanensis, Cochran, 1932) with comments on its morphological variation and conservation status

PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e10404
Author(s):  
Germán Chávez ◽  
Miguel A. Landestoy T ◽  
Gail S. Ross ◽  
Joaquín A. Ugarte-Núñez
Keyword(s):  
Morphological Variation ◽  
Phenotypic Variation ◽  
Conservation Status ◽  
Color Pattern ◽  
Geographic Range ◽  
The West ◽  
Cordillera Central ◽  
New Localities ◽  
Fitting In

We report here five new localities across the distribution of the lizard Sphaerodactylus samanensis, extending its current geographic range to the west, in the Cordillera Central of Hispaniola. We also report phenotypic variation in the color pattern and scutellation on throat and pelvic regions of males from both eastern and western populations, which is described below. Furthermore, based on these new data, we confirm that the species is not fitting in its current IUCN category, and in consequence propose updating its conservation status.

Residual Gas Reaction in the Electron Microscope: II The Design of a Gas-Control Chamber for Quantitative Observations

1969 ◽  
Vol 27 ◽  
pp. 82-83
Author(s):  
Chester J. Calbick ◽  
Richard E. Hartman
Keyword(s):  
Electron Beam ◽  
Electron Microscope ◽  
Local Environment ◽  
Chamber Pressure ◽  
Objective Lens ◽  
Ion Pump ◽  
Quantitative Studies ◽  
Precise Knowledge ◽  
Differential Pumping ◽  
And Control

Quantitative studies of the phenomenon associated with reactions induced by the electron beam between specimens and gases present in the electron microscope require precise knowledge and control of the local environment experienced by the portion of the specimen in the electron beam. Because of outgassing phenomena, the environment at the irradiated portion of the specimen is very different from that in any place where gas pressures and compositions can be measured. We have found that differential pumping of the specimen chamber by a 4" Orb-Ion pump, following roughing by a zeolite sorption pump, can produce a specimen-chamber pressure 100- to 1000-fold less than that in the region below the objective lens.

Enumeration and Identification of Asbestos Fibres in Water

1974 ◽  
Vol 32 ◽  
pp. 526-527 ◽  
Author(s):  
O. Mudroch ◽  
J. R. Kramer
Keyword(s):  
Water Supply ◽  
Water Samples ◽  
Drainage Basin ◽  
Lake Superior ◽  
Research Work ◽  
List Type ◽  
The West ◽  
Asbestos Fibre ◽  
Amphibole Asbestos

Approximately 60,000 tons per day of waste from taconite mining, tailing, are added to the west arm of Lake Superior at Silver Bay. Tailings contain nearly the same amount of quartz and amphibole asbestos, cummingtonite and actinolite in fibrous form. Cummingtonite fibres from 0.01μm in length have been found in the water supply for Minnesota municipalities.The purpose of the research work was to develop a method for asbestos fibre counts and identification in water and apply it for the enumeration of fibres in water samples collected(a) at various stations in Lake Superior at two depth: lm and at the bottom.(b) from various rivers in Lake Superior Drainage Basin.

Background Fitting in the Low-Loss Region of Electron Energy Loss Spectra

1990 ◽  
Vol 48 (2) ◽  
pp. 56-57
Author(s):  
C P Scott ◽  
A J Craven ◽  
C J Gilmore ◽  
A W Bowen
Keyword(s):  
Energy Loss ◽  
Multiple Scattering ◽  
Simple Form ◽  
Single Scattering ◽  
Low Loss ◽  
Characteristic Energy ◽  
Normal Method ◽  
Fitting In ◽  
Electron Energy Loss ◽  
Electron Energy Loss Spectra

The normal method of background subtraction in quantitative EELS analysis involves fitting an expression of the form I=AE-r to an energy window preceding the edge of interest; E is energy loss, A and r are fitting parameters. The calculated fit is then extrapolated under the edge, allowing the required signal to be extracted. In the case where the characteristic energy loss is small (E < 100eV), the background does not approximate to this simple form. One cause of this is multiple scattering. Even if the effects of multiple scattering are removed by deconvolution, it is not clear that the background from the recovered single scattering distribution follows this simple form, and, in any case, deconvolution can introduce artefacts.The above difficulties are particularly severe in the case of Al-Li alloys, where the Li K edge at ~52eV overlaps the Al L2,3 edge at ~72eV, and sharp plasmon peaks occur at intervals of ~15eV in the low loss region. An alternative background fitting technique, based on the work of Zanchi et al, has been tested on spectra taken from pure Al films, with a view to extending the analysis to Al-Li alloys.

Studies of the scanning ion beam sputter-cleaned MgO crystal surface by scanning reflection electron microscopy

1987 ◽  
Vol 45 ◽  
pp. 144-145
Author(s):  
H.-J. Ou ◽  
J. M. Cowley ◽  
A. A. Higgs
Keyword(s):  
Crystal Surface ◽  
Ion Beam ◽  
Carbon Film ◽  
Surface Region ◽  
Bulk Sample ◽  
Chamber Pressure ◽  
Specimen Preparation ◽  
Detailed Surface ◽  
Gate Control ◽  
Reflection Electron Microscopy

A scanning ion gun system has been installed on the specimen preparation chamber (pressure ∼5xl0-8 torr) of the VG-HB5 STEM microscope. By using the specimen current imaging technique, it is possible to use an ion beam to sputter-clean the preferred surface region on a bulk sample. As shown in figure 1, the X-Y raster-gate control of the scanning unit for the Krato Mini-Beam I is used to minimize the beam raster area down to a 800μm x800μm square region. With beam energy of 2.5KeV, the MgO cleavage surface has been ion sputter-cleaned for less than 1 minute. The carbon film or other contaminant, introduced during the cleavage process in air, is mostly removed from the MgO crystal surfaces.The immediate SREM inspection of this as-cleaned MgO surface, within the adjacent STEM microscope, has revealed the detailed surface structures of atomic steps, which were difficult to observe on the as-cleaved MgO surfaces in the previous studies.

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