Predicting Soil Expansion Force in Static Pipe Bursting Using Cavity Expansion Solutions and Numerical Modeling

• Author / Creator

  Ngan, Ka Hou

• The prediction of total pull force is critical to the design of static pipe bursting installation and soil expansion is the major component of the total pull force. However, there are currently limited methods available for its prediction. In this thesis, three cavity expansion solutions, namely Carter, Delft solution, and Yu and Houlsby, as well as numerical modeling using ABAQUS software, were used to predict soil expansion pressure acting upon the expander (bursting head) during static pipe bursting installation. The determined soil expansion pressures were then used to calculate the expansion force required for static pipe bursting with or without consideration of soil collapse due to crack propagation in pipe during expander’s forward advancement. Calculations were then compared to results from laboratory static pipe bursting experiments to evaluate the feasibility of the prediction methods.
  The comparison indicated that numerical and Yu and Houlsby solutions reasonably predicted the soil expansion force. Carter solution significantly overestimated the soil expansion force due to its small-strain assumption, while Delft solution moderately underestimated the results, as soil dilation was not considered. There was no significant difference between the results from numerical modeling and Yu and Houlsby solution due to the small scale of the experiments. However, Yu and Houlsby solution cannot capture the effects of depth of cover, initial borehole radius (only the radius ratio), and coefficient of lateral earth pressure.
  
  A parametric study for numerical and Yu and Houlsby solutions was also conducted to examine the influence of depth of cover as well as different initial and final borehole radii on the calculated expansion force using typical underground condition in Edmonton, Alberta, Canada. The results revealed that, although the soil expansion force obtained from Yu and Houlsby solution is higher than that obtained from numerical modeling, the difference decreases when the depth of cover increases. It was found that the Yu and Houlsby solution can provide a conservative prediction with a discrepancy of less than 30% for typical condition in Edmonton.

• Subjects / Keywords

  • Cavity expansion solutions
  • Static pipe bursting
  • Soil expansion force
  • ABAQUS

• Graduation date

  Spring 2015

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/R3S09D

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.