scholarly journals The use of numerical modelling to determine the stress within early age cemented paste used to backfill an underground stope

Author(s):  
Ryan Veenstra ◽  
Murray Grabinsky ◽  
William Bawden ◽  
Ben Thompson
2009 ◽  
Vol 61 (4) ◽  
pp. 299-307 ◽  
Author(s):  
G. Bertagnoli ◽  
G. Mancini ◽  
F. Tondolo

2021 ◽  
Vol 11 (21) ◽  
pp. 10400
Author(s):  
Weiqiang Guo ◽  
Xin Huang ◽  
Lijun Zhao ◽  
Ya Wei

The cast-in-place concrete base plate is a main member of the China Railway Track System (CRTS) III ballastless track structure that is prone to generating early transverse cracking. Such cracks can dramatically affect the performance and service life of the railway track structure. This study investigated the influence of temperature and moisture boundary conditions on early cracking behavior of the CRTS III base plate by using approaches of both in situ measurements and numerical modelling. In-site measurements of strain and temperature were made in four test series of CRTS III base plates under the same natural environmental condition but cured with different regimes, and a total of 96 measuring positions were monitored for up to 150 days. The results showed that the strain magnitude and distribution in the field base plate, the initial time at cracking, and the observed cracking pattern varied significantly between the different test series. In order to understand the mechanisms that create these transverse cracks and to provide guidelines for the current curing strategy during construction, the characteristics of temperature-induced and moisture-induced stresses were analyzed by using 3D numerical modelling and by considering early-age concrete creep properties, meteorological factors, and the influence from environmental boundary conditions. The calculated results revealed that early-age transverse cracking in CRTS III base plate depends more on drying shrinkage stress than temperature stress. By conducting this study, we expect to provide guidance for reducing or eliminating early cracks of CRTS III concrete base plate.


1982 ◽  
Vol 47 (4) ◽  
pp. 373-375 ◽  
Author(s):  
James L. Fitch ◽  
Thomas F. Williams ◽  
Josephine E. Etienne

The critical need to identify children with hearing loss and provide treatment at the earliest possible age has become increasingly apparent in recent years (Northern & Downs, 1978). Reduction of the auditory signal during the critical language-learning period can severely limit the child's potential for developing a complete, effective communication system. Identification and treatment of children having handicapping conditions at an early age has gained impetus through the Handicapped Children's Early Education Program (HCEEP) projects funded by the Bureau of Education for the Handicapped (BEH).


1964 ◽  
Vol 03 (01) ◽  
pp. 11-19 ◽  
Author(s):  
A. Proppe

SummaryCase histories suitable for statistical evaluation can be found even as far back as in the Corpus Hippocraticum. Such simple data as the patient’s age, body weight, size, the date of menarche, etc. are practically always included in the case records, and it is demonstrated that, when such data are recorded in a system of documentation suitable for mechanical sorting, it may enable us to draw conclusions of very great importance. Mechanical registration methods have revealed that, in the determination and recording of data as hitherto carried out. there has been a surprisingly large number of errors and a high degree of unreliability. This view has a considerable influence on modern clinical methods; it renders a more democratic relation between physician and patient necessary and makes clear the need for measures to enhance the reliability of diagnosis and treatment of pathological conditions. The author illustrates this view with reference to the mechanical falsification of the thesis of the proneness of early age groups to lupus vulgaris, furthermore with reference to the mechanical rationalization of modern routine diagnostic methods, to the constant surveillance of adverse effects on public health and to the protection against allergic reactions with the aid of recording systems of personal allergy and intolerance data with mechanical sorting and computer techniques.


1990 ◽  
Vol 63 (01) ◽  
pp. 013-015 ◽  
Author(s):  
E J Johnson ◽  
C R M Prentice ◽  
L A Parapia

SummaryAntithrombin III (ATIII) deficiency is one of the few known abnormalities of the coagulation system known to predispose to venous thromboembolism but its relation to arterial disease is not established. We describe two related patients with this disorder, both of whom suffered arterial thrombotic events, at an early age. Both patients had other potential risk factors, though these would normally be considered unlikely to lead to such catastrophic events at such an age. Thrombosis due to ATIII deficiency is potentially preventable, and this diagnosis should be sought more frequently in patients with arterial thromboembolism, particularly if occurring at a young age. In addition, in patients with known ATIII deficiency, other risk factors for arterial disease should be eliminated, if possible. In particular, these patients should be counselled against smoking.


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