scholarly journals Finite Element Analysis of Natural Thawing Heat Transfer of Artificial Frozen Soil in Shield-Driven Tunnelling

2020 ◽  
Vol 2020 ◽  
pp. 1-18
Author(s):  
Yong Fu ◽  
Jun Hu ◽  
Jia Liu ◽  
Shengbin Hu ◽  
Yunhui Yuan ◽  
...  

The technology of artificial horizontal freezing method is increasingly being used in the soil reinforcement of urban underground projects such as shield-driven tunnelling. Compared with the freezing process, the thawing process is more complicated, and the thawing behavior of artificial frozen soil surrounding shield-driven tunnels has not been well investigated in both the academic and industrial domains. This study, therefore, aims to investigate the natural thawing heat transfer behavior of artificial horizontal frozen soil in shield-driven tunnelling using a three-dimensional finite element method. The finite element modelling is based on the horizontal freezing reinforcement project of Chating Station to Jiqingmen Station Tunnel in the Nanjing Metro Line 2. Validation between finite element results and site measured results is firstly conducted. The natural thawing temperature field contours as well as the radial and longitudinal distributions of natural thawing temperature in the frozen soil surrounding the tunnel are then explicitly examined. Furthermore, sensitivity analysis of influencing factors such as the thermal conductivity, latent heat of phase change, ambient temperature inside tunnel, freezing time, and original ground temperature is carried out. The results and findings of this study may enrich the current limited database and enable a better understanding of natural thawing heat transfer behavior of artificial frozen soil in shield-driven tunnelling.

2011 ◽  
Vol 418-420 ◽  
pp. 1698-1702
Author(s):  
Qing Guo Liu ◽  
Xing Zhong Zhang ◽  
Zheng Yi Jiang ◽  
Yan Chao Sun ◽  
Bao Jun Shi ◽  
...  

The straightening of curved slab results in a greater straightening strain. During the process of multi-point straightening, the peak value of the straightening strain rate will appear at each straightening point. If the strain rate is too large, the straightening cracks will appear. Solidification and heat transfer of a slab is analyzed and the generation of the solidified shell and the three-dimension temperature field of the slab are calculated by using three-dimensional finite element method (FEM). Based on the finite element analysis of five-point straightening of the curved slab, the strain and strain rate of each straightening point were obtained, which is a base of the analysis of straightening cracks.


2020 ◽  
Vol 57 (2) ◽  
pp. 277-293 ◽  
Author(s):  
Mahmoud G. Hussein ◽  
Mohamed A. Meguid

Soil reinforcement has rapidly become one of the most common soil improvement techniques used in geotechnical engineering. Understanding the behavior of a geogrid under pullout loading is essential for the analysis and design of reinforced soil systems. The overall behavior of reinforced soils is generally dependent on the properties of the geogrid material, the backfill soil, and the interface condition. Modeling the three-dimensional aspects of soil–geogrid interaction under pullout loading condition is numerically challenging and requires special consideration of the different modes of resistance that contribute to the pullout capacity of the geogrid reinforcement. This study describes the results of a three-dimensional finite-element analysis that has been developed to investigate the behavior of a biaxial geogrid embedded in granular backfill material and subjected to pullout loading. The modeling approach considers the noncontinuous nature of the geogrid geometry and the elastoplastic response of the geogrid material. Model validation is performed by simulating laboratory-size pullout test and comparing the experimental data with the analytical as well as numerically calculated results. The detailed behavior of the geogrid and the surrounding backfill is investigated using the proposed numerical approach. Conclusions are made to highlight the suitability of this technique for analyzing similar soil–structure interaction problems.


2007 ◽  
Vol 35 (3) ◽  
pp. 226-238 ◽  
Author(s):  
K. M. Jeong ◽  
K. W. Kim ◽  
H. G. Beom ◽  
J. U. Park

Abstract The effects of variations in stiffness and geometry on the nonuniformity of tires are investigated by using the finite element analysis. In order to evaluate tire uniformity, a three-dimensional finite element model of the tire with imperfections is developed. This paper considers how imperfections, such as variations in stiffness or geometry and run-out, contribute to detrimental effects on tire nonuniformity. It is found that the radial force variation of a tire with imperfections depends strongly on the geometrical variations of the tire.


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