scholarly journals Frost protection of buried PVC water mains in western Canada

1994 ◽  
Vol 31 (4) ◽  
pp. 491-501 ◽  
Author(s):  
K. Sepehr ◽  
L.E. Goodrich
Keyword(s):  
Transfer Model ◽  
Model Study ◽  
Water Mains ◽  
Dimensional Finite Element ◽  
Insulation Systems ◽  
Strength Material ◽  
Frost Protection ◽  
Thermal Bridging ◽  
Frost Penetration ◽  
Pipe Insulation

Although desirable for many reasons, controlled low-strength material – controlled density fill (nonshrinkable fill) has the potential to promote rapid frost penetration within the trench when used as a backfill material in waterworks construction and repair projects. This paper describes results of a two-dimensional finite-element heat-transfer model study carried out to investigate the effectiveness of various insulation systems for frost and frost-heave protection of buried waterlines. Combinations of nonshrinkable fill with horizontal insulation boards, cylindrical pipe insulation, and inverted U-shaped insulations were investigated. It was shown that, while moderate thicknesses of insulation could be found to protect the pipe from freezing, thermal-bridging effects make the location of the maximum frost penetration depth sensitive to details of the insulation geometry. The use of different combinations of insulating backfills was also investigated, and it was shown that a backfill layer of moderate insulating value placed high in the trench may be most advantageous. Key words : frost, frost protection, insulation, waterlines, nonshrinkable fill, numerical analysis.

Heat Transfer in Grinding-Hardening of a Cylindrical Component

2011 ◽  
Vol 325 ◽  
pp. 35-41 ◽  
Author(s):  
Thai Nguyen ◽  
Liang Chi Zhang ◽  
Da Le Sun
Keyword(s):  
Heat Transfer ◽  
Three Dimensional ◽  
Hardened Layer ◽  
Transfer Model ◽  
Plunge Grinding ◽  
Cylindrical Component ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element ◽  
Grinding Hardening ◽  
Good Agreement

A three-dimensional finite element heat transfer model incorporating a moving heat source was developed to investigate the heat transfer mechanism in grinding-hardening of a cylindrical component. The model was applied to analyze the grinding-hardening of quenchable steel 1045 by two grinding methods, traverse and plunge grinding. It was found that the heat generated can promote the martensitic phase transformation in the ground workpiece. As a result, a hardened layer with a uniform thickness can be produced by traverse grinding. However, the layer thickness generated by plunge grinding varies circumferentially. The results are in good agreement with the experimental observations.

Numerical Analysis of Optimization Design for Insulation Layer in Cold Regions Tunnel

2014 ◽  
Vol 1065-1069 ◽  
pp. 368-372 ◽  
Author(s):  
He Song ◽  
Chao Liang Ye ◽  
Jun Feng Mi
Keyword(s):  
Optimization Design ◽  
Frost Damage ◽  
Surrounding Rock ◽  
Temperature Fields ◽  
Insulation Layer ◽  
Cold Region ◽  
Element Analysis ◽  
Penetration Length ◽  
Dimensional Finite Element ◽  
Frost Penetration

Setting of insulation layer is widely recognized to prevent frost damage for tunnels constructed in cold region. Optimization design of insulation layers, however, still need deeply investigate. In this paper, taking Houanshan tunnel as example, two-dimensional finite element analysis on the optimization design of insulation layers has been carried out by ABAQUS. The tunnel temperature fields due to various thickness and length of insulation layer are numerically analyzed. It shows that ,1)4.85°C increased at backside of insulation layer with thickness of 5cm, while 5.8°C increased for thickness of 7cm;2) frozen depth of surrounding rock decrease with the increase of insulation layer thickness. The farther distance to tunnel portal, the smaller thickness of insulation layer required to prevent the surrounding rock from freezing;3)According to analysis, frost penetration length should be 450~500m before tunnel holing-through ,while 720m~830m after tunnel holing-through.

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