University of Texas
Experimental Facility Workshop

Stiffness-based Ground Deformation Predictions Workshop
November 5, 2018

You are invited to attend a workshop on Stiffness-based Ground Deformation Predictions in Seattle, WA. This workshop is hosted by the Natural Hazards Engineering Research Infrastructure Equipment Facility at the University of Texas at Austin (NHERI@UTexas). The workshop will be held from 8 am to 5 pm on Monday, 5 November 2018 at the Residence Inn by Marriott Seattle Downtown/Convention Center (1815 Terry Ave, Seattle, WA 98101). The proposed workshop will include a half-day seminar followed by a half-day field demonstration of field tests from NSF-founded Project CMMI-1650170 (Project title: RAPID Collaborative Research: Spatial variability of small-strain stiffness, Go, and the effect on ground movements related to geotechnical construction in urban areas, Project PI: Richard J Finno).

Increased dense urbanization and traffic congestion in the US and many parts of the world are prompting a significant demand for underground space. However, development of underground space may result in damage to adjacent infrastructure. Recent research has resulted in advances in techniques to predict, monitor, and control ground movements during excavation. These efforts have shown that small-strain shear stiffness, Go, and the variation of shear modulus with strain is a key ingredient in any constitutive model used to predict the relatively small ground movements. Natural soil sites are heterogeneous and Go values vary laterally and with depth around the plan area of typical urban excavations. Measurements of Go will be made at the proposed new Washington State Convention Center (WSCC) Building, a sixteen-story building with a deep excavation. The research effort includes:

  1. obtaining spatially dependent Go values prior to start of construction using NHERI@UTexas field equipment,
  2. analyzing the seismic data via advanced 3-D full waveform tomography to develop a 3-D map of Go,
  3. conducting detailed experimental programs using both advanced triaxial and combined dynamic torsional resonant column and cyclic torsional shear devices on thin-walled tube and block samples,
  4. developing soil parameters for an advanced constitutive model that includes small-strain stiffness using optimization techniques based on the laboratory data and the field measurements collected during excavation,
  5. collecting and recording field performance and relating it to construction activities during construction, and,
  6. simulating the excavation process using the finite element method.

The NHERI@UTexas Stiffness-based Ground Deformation Predictions Workshop will highlight the potential use of NHERI@UTexas equipment for non-intrusive imaging of geotechnical systems using surface wave measurements and full waveform inversion methods. Specifically, during the workshop, we will use the urban, mobile, hydraulic shaker named Thumper to generate dynamic vertical loadings at the ground surface. The waveforms recorded from this testing will be provided to all workshop participants and other interested researchers to use in ground deformation predictions.

Those with ideas about small, proof-of-concept tests that could piggyback on the workshop and be used to generate preliminary proposal data are encouraged to contact us in advance of the workshop. Please contact Farnyuh Menq (fymenq@utexas.edu), NHERI@UTexas Site Operations Manager, with any questions regarding the workshop, piggyback proof-of-concept tests, or the equipment facility.

Workshop Registration