scholarly journals Effect of Deficiencies in the Tunnel Crown Thickness on Pressure Tunnels with Posttensioned Concrete Linings

2018 ◽  
Vol 2018 ◽  
pp. 1-14 ◽  
Author(s):  
Gan Qin ◽  
Shengrong Cao ◽  
Fan Yang
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Yellow River ◽  
Three Dimensional ◽  
Element Model ◽  
Concrete Lining ◽  
The Yellow River ◽  
Posttensioned Concrete ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element

This paper investigates the effect of deficiencies in the tunnel crown thickness on pressure tunnels with the posttensioned concrete lining. Based on the lining parameters of the Yellow River Crossing Tunnel, the modeling approach of the posttensioned concrete lining is introduced in detail and a three-dimensional finite element model is established. The three-dimensional finite element model is validated by experimental results from the full-scale model experiment of the Yellow River Crossing Tunnel. Special attention is given to the changes in the deformation, radial displacement, and circumferential stress of the posttensioned concrete lining with gradual decreases in the tunnel crown thickness. The calculation results show that the influence scopes of deficiencies in the tunnel crown thickness are mainly concentrated in the crown and its adjacent parts. The posttensioned concrete lining can still maintain a satisfactory stress state when deficiencies in the tunnel crown thickness exist, and undesirable stress levels may be caused only when the tunnel crown thickness decreases below a certain threshold. Furthermore, cracks are most likely to occur at the external and internal surfaces of the crown and at the internal surface of the crown’s adjacent parts, which is useful for taking measurements regarding the lining tightness and stability.

scholarly journals MODELLING FROM THE PAST: THE LEANING SOUTWEST TOWER OF CAERPHILLY CASTLE 1539-2015

2017 ◽  
Vol IV-2/W2 ◽  
pp. 221-227 ◽  
Author(s):  
O. E. C. Prizeman ◽  
V. Sarhosis ◽  
A. M. D’Alri ◽  
C. J. Whitman ◽  
G. Muratore
Keyword(s):  
Finite Element ◽  
Structural Analysis ◽  
Finite Element Model ◽  
Three Dimensional ◽  
Element Model ◽  
Present Condition ◽  
Long Term Stability ◽  
Dimensional Finite Element ◽  
The Uk ◽  
Three Dimensional Finite Element

Caerphilly Castle (1268-70) is the first concentric castle in Britain and the second largest in the UK. The dramatic inclination of its ruinous south west tower has been noted since 1539. Comparing data from historical surveys and a terrestrial laser scan undertaken in 2015, this paper seeks to review evidence for the long-term stability of the tower. Digital documentation and archival research by architects is collated to provide data for structural analysis by engineers. A terrestrial laser scan was used to create a detailed three dimensional finite element model to enable structural analysis of the current shape of the tower made by tetrahedral elements. An automated strategy has been implemented for the transformation of the complex three dimensional point cloud into a three dimensional finite element model. Numerical analysis has been carried out aiming at understanding the main structural weaknesses of the tower in its present condition. Comparisons of four sets of data: 1539, 1830, 1870 and 2015 enabled us to determine change albeit between very different methods of measurement.

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