Title page for ETD etd-04242006-210518

Type of Document Dissertation
Author Wang, Jianfeng
Author's Email Address jiwang3@vt.edu
URN etd-04242006-210518
Title Micromechanics of Granular Media: A Fundamental Study of Interphase Systems
Degree PhD
Department Civil Engineering
Advisory Committee
Advisor Name Title
Dove, Joseph E. Committee Chair
Gutierrez, Marte S. Committee Co-Chair
Filz, George M. Committee Member
Kriz, Ronald D. Committee Member
Mauldon, Matthew Committee Member
Wang, Linbing Committee Member
  • interface strength
  • particulate-solid interaction
  • microscopic deformation
  • interphase behavior
Date of Defense 2006-04-21
Availability unrestricted
The interphase is a localized region adjacent to a manufactured inclusion that is surrounded by granular soil. These regions are ubiquitous in civil infrastructure and often are components of large-scale composite systems. The interphase region influences load-deformation behavior of the entire composite system. However, mechanisms that control the mechanical behavior of the interphase region and, in turn, control the composite structure behavior, are not clearly understood. Few relationships exist for predicting interphase behavior from properties of granular materials and the inclusion surface that can be measured in the laboratory.

A two dimensional discrete element model of a general interphase system was developed and validated against laboratory data. Numerical experiments are conducted with varying soil to inclusion relative geometry. A new micromechanics-based approach, which utilizes microscopic quantities to explain the mechanics of granular media from a continuum point view, is adopted to investigate the mechanisms that underlie the interphase behavior.

It is shown that the grain to inclusion surface relative geometry controls the degree of granular media strength mobilization by controlling development of fabric and contact force anisotropy inside the interphase region. A unique bilinear relationship exists between the mobilized granular media strength and the principal direction of average contact force anisotropy at the interface between the particles touching the surface and the inclusion. These findings suggest the problem is one of contact and can not be solved using purely geometric correlations, as past research presumed. A fundamental mechanism of behavior, long sought in geomechanics problems, is presented. Publications resulting from this research are significant and original contributions to the geoengineering, material science, geophysics and granular physics literature.

  Filename       Size       Approximate Download Time (Hours:Minutes:Seconds) 
 28.8 Modem   56K Modem   ISDN (64 Kb)   ISDN (128 Kb)   Higher-speed Access 
  Appendix.pdf 176.20 Kb 00:00:48 00:00:25 00:00:22 00:00:11 < 00:00:01
  Chapter-1.pdf 575.62 Kb 00:02:39 00:01:22 00:01:11 00:00:35 00:00:03
  Chapter-2.pdf 16.73 Mb 01:17:27 00:39:50 00:34:51 00:17:25 00:01:29
  Chapter-3.pdf 8.63 Mb 00:39:57 00:20:32 00:17:58 00:08:59 00:00:46
  Chapter-4.pdf 10.56 Mb 00:48:54 00:25:08 00:22:00 00:11:00 00:00:56
  Chapter-5.pdf 3.90 Mb 00:18:02 00:09:16 00:08:07 00:04:03 00:00:20
  Chapter-6.pdf 743.76 Kb 00:03:26 00:01:46 00:01:32 00:00:46 00:00:03
  Chapter-7.pdf 42.41 Kb 00:00:11 00:00:06 00:00:05 00:00:02 < 00:00:01
  Frontmatter.pdf 154.43 Kb 00:00:42 00:00:22 00:00:19 00:00:09 < 00:00:01

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