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Toppling Analysis of Precariously Balanced Rocks under Earthquake Excitation


Veeraraghavan, Swetha (2015) Toppling Analysis of Precariously Balanced Rocks under Earthquake Excitation. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/Z98W3B9Z.


Toppling analysis of a precariously balanced rock (PBR) can provide insights into the nature of ground motion that has not occurred at that location in the past and, by extension, realistic constraints on peak ground motions for use in engineering design. Earlier approaches have targeted simplistic 2-D models of the rock or modeled the rock-pedestal contact using spring-damper assemblies that require re-calibration for each rock. These analyses also assume that the rock does not slide on the pedestal. Here, a method to model PBRs in three dimensions is presented. The 3-D model is created from a point cloud of the rock, the pedestal, and their interface, obtained using Terrestrial Laser Scanning (TLS). The dynamic response of the model under earthquake excitation is simulated using a rigid body dynamics algorithm. The veracity of this approach is demonstrated by comparisons against data from shake table experiments. Fragility maps for toppling probability of the Echo Cliff PBR and the Pacifico PBR as a function of various ground motion parameters, rock-pedestal interface friction coefficient, and excitation direction are presented. The seismic hazard at these PBR locations is estimated using these maps. Additionally, these maps are used to assess whether the synthetic ground motions at these locations resulting from scenario earthquakes on the San Andreas Fault are realistic (toppling would indicate that the ground motions are unrealistically high).

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:Rigid body dynamics, Precariously balanced rocks
Degree Grantor:California Institute of Technology
Division:Engineering and Applied Science
Major Option:Civil Engineering
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Krishnan, Swaminathan (advisor)
  • Hall, John F. (co-advisor)
Thesis Committee:
  • Heaton, Thomas H. (chair)
  • Asimaki, Domniki
  • Hudnut, Kenneth W.
  • Krishnan, Swaminathan
  • Hall, John F.
Defense Date:7 May 2015
Funding AgencyGrant Number
National Science FoundationUNSPECIFIED
United States Geological SurveyUNSPECIFIED
Southern California Earthquake CenterUNSPECIFIED
Record Number:CaltechTHESIS:05252015-121408938
Persistent URL:
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:8885
Deposited By: Swetha Veeraraghavan
Deposited On:06 Oct 2016 16:17
Last Modified:28 Oct 2021 23:12

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