Design of tunnel lining in rock for long term time effects

1981 ◽  
Vol 18 (1) ◽  
pp. 24-39 ◽  
Author(s):  
K. Y. Lo ◽  
Clement M. K. Yuen
Keyword(s):  
Time Lapse ◽  
Time Dependent ◽  
Initial Stresses ◽  
Time Interaction ◽  
Underground Openings ◽  
Rock Structure ◽  
Rock Movement ◽  
Made In

Excavation of underground openings in rock relieves the in situ state of stresses, providing an initiating mechanism for time-dependent deformation in shaly rocks to occur. The construction of a permanent lining restrains the rock movement, resulting in an increase with time of pressure acting on the lining.Closed form solutions for this problem of rock structure – time interaction of circular tunnels have been developed, taking into account (a) the state of initial stresses, (b) the time-dependent properties of the lining as well as the rock, and (c) the time lapsed between excavation and lining. Expressions for lining pressures, stresses, thrusts, and moments are given for both "no slip" and "full slip" interface conditions.The effects of material parameters, lining flexibilities, and time lapse on quantities of engineering interest are studied and their implications on design illustrated.The results of analysis are compared with the field observations made in three tunnels. It is shown that the theoretical results are consistent with the observed extent and location of cracking in these tunnels.It is suggested that the methods proposed may be used for design considerations of permanent linings of tunnels in rock exhibiting significant time-dependent deformation.

In Situ Tests on Creep Behavior of Rock Mass with Joint or Shearing Zone in Foundation of Large-Scale Hydroelectric Projects

2004 ◽  
Vol 261-263 ◽  
pp. 1097-1102 ◽  
Author(s):  
Jian Liu ◽  
Xia Ting Feng ◽  
Xiu Li Ding ◽  
Huo Ming Zhou
Keyword(s):  
Rock Mass ◽  
Creep Behavior ◽  
Large Scale ◽  
Time Dependent ◽  
Three Gorges Project ◽  
Three Gorges ◽  
The Three Gorges ◽  
The Three Gorges Project

The time-dependent behavior of rock mass, which is generally governed by joints and shearing zones, is of great significance for engineering design and prediction of long-term deformation and stability. In situ creep test is a more effective method than laboratory test in characterizing the creep behavior of rock mass with joint or shearing zone due to the complexity of field conditions. A series of in situ creep tests on granite with joint at the shiplock area of the Three-Gorges Project and basalt with shearing zone at the right abutment of the Xiluodu Project were performed in this study. Based on the test results, the stress-displacement-time responses of the joints and basalt are analyzed, and their time-dependent constitutive model and model coefficients are given, which is crucial for the design to prevent the creep deformations of rock masses from causing the failure of the operation of the shiplock gate at the Three-Gorges Project and long-term stability of the Xiluodu arc dam.

A self-contained underwater time-lapse camera for in situ long-term observations

1979 ◽  
Vol 55 (3) ◽  
pp. 239-246 ◽  
Author(s):  
K. Fedra ◽  
R. Machan
Keyword(s):  
Time Lapse

scholarly journals Correlation between daily infections and fatality rate due to Covid-19 in Germany

2020 ◽  
Author(s):  
Dieter Mergel
Keyword(s):  
Symptom Onset ◽  
Public Life ◽  
Face Mask ◽  
Time Lapse ◽  
Time Dependent ◽  
Reproduction Rate ◽  
Fatality Rate ◽  
Trend Line ◽  
Vulnerable People

The officially reported daily Covid-19 fatality rate is modelled with a trend line based on a nominal day-to-day reproduction rate and a cosine to take account of weekly fluctuations. Although the time trajectories of officially reported infections and fatalities are pronouncedly different, the reproduction rates obtained therefrom are similar. The long-term effective reproduction rate is around 0.835 and the administrative measures to contain the pandemic seem not to have an immediate reducing effect but well the ease of restrictions an increasing one. The fatality trajectory represented by its trend line can be projected from the number of daily infections by assuming a time lapse between symptom onset and death between 17 and 19 days and a time-dependent nominal lethality. The time trajectory of this lethality increases from 2.5% at March 16 when public life was restricted to 6% within 20 days indicating relatively more infections of vulnerable people. After stipulating face mask wearing at April 27, the nominal lethality decreases down to 1% later in summer. A detailed analysis shows that mask wearing really reduces the number of fatal infections and the officially reported daily infections in May and June are less lethal than before.

scholarly journals Pathogenic properties of enterohepatic Helicobacter spp. isolated from rhesus macaques with intestinal adenocarcinoma

2014 ◽  
Vol 63 (7) ◽  
pp. 1004-1016 ◽  
Author(s):  
Kvin Lertpiriyapong ◽  
Laurence Handt ◽  
Yan Feng ◽  
Thomas W. Mitchell ◽  
Kenneth E. Lodge ◽  
...  
Keyword(s):  
Rhesus Monkey ◽  
Rhesus Macaques ◽  
Detection Methods ◽  
Pathogenic Potential ◽  
Rrna Sequencing ◽  
Similar Disease ◽  
T84 Cell Line ◽  
Made In

Considerable progress has been made in understanding the roles of Helicobacter pylori in inflammation and gastric cancer; however, far less is known about the roles of enterohepatic Helicobacter species (EHS) in carcinogenesis and their zoonotic or pathogenic potential. We determined the prevalence of EHS infection in a cohort of geriatric rhesus monkeys in which intestinal adenocarcinoma (IAC) is common and investigated the association between EHS infection and IAC. The cohort consisted of 36 animals, 14 of which (age 26–35 years) had IAC. Of the 36 rhesus, 35 (97 %) were positive for EHS using PCR or bacterial isolation from faeces, colonic or tumour tissues. Only a single rhesus, which had IAC, was negative for EHS by all detection methods. The EHS identified by 16S rRNA sequencing in this study were from three Helicobacter taxa: Helicobacter macacae (previously rhesus monkey taxon 1), Helicobacter sp. rhesus monkey taxon 2, previously described from strain MIT 99-5507, and Helicobacter sp. rhesus monkey taxon 4, related to Helicobacter fennelliae. Thirteen of 14 monkeys with IAC were positive for either H. macacae (7/13, 54 %), EHS rhesus monkey taxon 4 (4/13, 31 %) or a mixture of the two EHS (2/13, 15 %). These results indicate that EHS are prevalent among aged rhesus macaques with IAC. Using Helicobacter genus-specific florescent in situ hybridization, EHS were detected on the surface of colonic epithelia of infected monkeys. All Helicobacter isolates, including H. macacae, effectively adhered to, invaded, and significantly induced proinflammatory genes, including IL-8, IL-6, TNF-α and iNOS, while downregulating genes involved in the function of inflammasomes, particularly IL-1β, CASPASE-1, NRLP3, NLRP6 and NLRC4 in the human colonic T84 cell line (P<0.0001). These results suggest that EHS may represent an aetiological agent mediating diarrhoea, chronic inflammation, and possibly intestinal cancer in non-human primates, and may play a role in similar disease syndromes in humans. Downregulation of inflammasome function may represent an EHS strategy for long-term persistence in the host and play a role in inducing pathological changes in the host’s lower bowel.

Design of buried structures in squeezing rock in Toronto, Canada

1987 ◽  
Vol 24 (2) ◽  
pp. 232-241 ◽  
Author(s):  
K. Y. Lo ◽  
B. H. Cooke ◽  
D. D. Dunbar
Keyword(s):  
Laboratory Testing ◽  
Site Investigation ◽  
Horizontal Stress ◽  
Time Dependent ◽  
Buried Structures ◽  
Analysis And Design ◽  
Pumping Station ◽  
Time Interaction ◽  
Rock Structure ◽  
Squeezing Rock

The construction of the Domed Stadium in Toronto necessitated the relocation of the John Street Pumping Station and associated water supply tunnels for the downtown Toronto area. The proposed structures include tunnels, shafts, and a new pumping station built in or founded on rock. The shale rock of the Georgian Bay formation is known to possess high horizontal stresses and time-dependent deformation and at this site contains numerous horizontal fractures filled with clay seams. This paper presents the results of the site investigation, field and laboratory testing, analysis, and design for the buried structures. Special provisions for "rock squeeze" for different structures are also described. Key words: tunnels, shafts, shale, squeezing rock, horizontal stress, rock–structure–time interaction.

Evaluating the Structural Capacity of Concrete Elements through In Situ Instrumentation

2013 ◽  
Vol 569-570 ◽  
pp. 382-389 ◽  
Author(s):  
David Byrne ◽  
Jamie Goggins
Keyword(s):  
Load Capacity ◽  
Time Dependent ◽  
Concrete Members ◽  
In Situ Data ◽  
Structural Capacity ◽  
National University ◽  
Term Performance ◽  
Concrete Elements

The difficulty in predicting the long term load capacity of concrete elements is well documented. Time dependent effects such as creep and shrinkage coupled with varying loading events, particularly during construction, can all have an adverse effect on the long term performance of a concrete structure. This paper proposes a method that utilises in-situ instrumentation to predict the load carrying capacity of concrete members. During the construction of the Engineering building at the National University of Ireland, Galway over 260 sensors were embedded in a number of key concrete elements. The sensors are being continually monitored with the use of automatic datalogging equipment and the data is being used to monitor changes in geometric and material properties along with the subsequent time dependent deterioration of the elements. The paper will illustrate how the in-situ data from the demonstrator building can be used to estimate the real time behaviour of the concrete elements and how these elements might respond to future changes in use and potential retrofitting. A cost analysis will show how such a monitoring system can be used to reduce the uncertainty levels involved when retrofitting concrete buildings.

Experimental study of the formation of the bulboventricular loop in the chick

Development ◽  
1972 ◽  
Vol 27 (3) ◽  
pp. 623-637
Author(s):  
Alfredo Castro-Quezada ◽  
Bernardo Nadal-Ginard ◽  
María V. de la Cruz
Keyword(s):  
Electron Microscope ◽  
Time Lapse ◽  
Mirror Image ◽  
Heart Tube ◽  
Removal Experiments ◽  
Atrioventricular Groove ◽  
The Right ◽  
Time Lapse Photography ◽  
Made In

The formation of the normal bulboventricular loop (convex to the right) and the inverted loop (convex to the left) produced by the Lepori technique in chick embryos was studied. The development of the loops was recorded by means of diagrams, photographs and microscopic time-lapse photography. Electron-microscope studies were also made. The normal loop was studied by means of labelling and removal experiments on the heart tube. The results demonstrated that the fusion of both cardiac primordia is made in stage 9 — in the mid-line of the embryo and that the first asymmetry of the heart tube appears in stage 10. The truncus region developed in situ directed towards the right after the fusion of both cardiac primordia, and in this region the electron-microscope study demonstrated a gradient of caudo-cephalic differentiation. In stage 10 the left caudal groove is the prospective interventricular groove, but the right caudal groove is not the right atrioventricular groove as had been stated by others. The asymmetric incorporation of both primordia begins in stage 11 —, when the curvature of the loop is already developing. In the removal experiments it was evident that the different portions of the cardiac tube in situ are orientated in space independently of the whole of the loop. The formation of the experimentally inverted loop is a mirror-image of the normal loop and appears to be originated through mechanic traction of the cardiac tube by the left splachnopleure and not by a faster displacement of the right cardiac primordia.

scholarly journals 137Cs Gamma-ray detection at Summit, Greenland

1994 ◽  
Vol 40 (134) ◽  
pp. 87-92 ◽  
Author(s):  
Philip P. Dunphy ◽  
Jack E. Dibb
Keyword(s):  
Radioactive Isotope ◽  
Gamma Ray ◽  
Pulse Height ◽  
Radiation Detectors ◽  
Power Supplies ◽  
Scintillation Crystal ◽  
Γ Ray ◽  
Made In

AbstractGlobal fall-out from atmospheric testing of thermonuclear weapons produced horizon markers corresponding to the initiation of testing in 1953 and the maximum fall-out in 1963. The radioactive isotope137Cs associated with these events has a half-life of 30.2 years. Therefore, with the appropriate radiation detectors, this fall-out can be used as a long-term temporal indicator in glaciers and snowpack. A prototype γ-ray detector system was successfully tested and was used to make in-situ measurements of the137Cs marker in a borehole at Summit, Greenland. The system consisted of a 7.6 cm by 7.6 cm NaI(Tl) scintillation crystal/photomultiplier detector, commercial pre-amplifier, amplifier and power supplies, and a microcomputer-based pulse-height analyzer. The measurements were made in boreholes of 25.4 cm and 12.7 cm diameter to depths of 22 m. Based on the results reported here, the γ-ray detection technique promises to be a powerful way to locate quickly horizon markers in the field.

scholarly journals 137Cs Gamma-ray detection at Summit, Greenland

1994 ◽  
Vol 40 (134) ◽  
pp. 87-92
Author(s):  
Philip P. Dunphy ◽  
Jack E. Dibb
Keyword(s):  
Radioactive Isotope ◽  
Gamma Ray ◽  
Pulse Height ◽  
Radiation Detectors ◽  
Power Supplies ◽  
Scintillation Crystal ◽  
Γ Ray ◽  
Made In

AbstractGlobal fall-out from atmospheric testing of thermonuclear weapons produced horizon markers corresponding to the initiation of testing in 1953 and the maximum fall-out in 1963. The radioactive isotope 137Cs associated with these events has a half-life of 30.2 years. Therefore, with the appropriate radiation detectors, this fall-out can be used as a long-term temporal indicator in glaciers and snowpack. A prototype γ-ray detector system was successfully tested and was used to make in-situ measurements of the 137Cs marker in a borehole at Summit, Greenland. The system consisted of a 7.6 cm by 7.6 cm NaI(Tl) scintillation crystal/photomultiplier detector, commercial pre-amplifier, amplifier and power supplies, and a microcomputer-based pulse-height analyzer. The measurements were made in boreholes of 25.4 cm and 12.7 cm diameter to depths of 22 m. Based on the results reported here, the γ-ray detection technique promises to be a powerful way to locate quickly horizon markers in the field.

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