Development and validation of the downhole freestanding shear device (DFSD) for measuring the dynamic properties of clay.

Details

• Creators:
  Riemer, Michael ; Safaqah, Osama ; Grizzle, Carlton ; Roblee, Clifford
• Corporate Creators:
  University of California, Berkeley. Department of Civil and Environmental Engineering ; California. Dept. of Transportation. Division of Research and Innovation
• Corporate Contributors:
  United States. Federal Highway Administration
• Subject/TRT Terms:
  • Clay soils
  • California
  • Testing
  • Drill core analysis
• Publication/ Report Number:
  CA03-0024
• Resource Type:
  Tech Report
• Geographical Coverage:
  California
• Corporate Publisher:
  California. Dept. of Transportation. Division of Research and Innovation
• Abstract:
  The Downhole Freestanding Shear Device (DFSD) is an innovative tool developed for in situ measurement of dynamic ; properties (modulus and damping) of clay soils over a broad range of strains. The device essentially performs ; laboratory-quality torsional shear testing on a “freestanding” column of soil carved below the bottom of a borehole. ; Other shear testing modes may also be accommodated. The DFSD design and testing procedure minimizes sample ; disturbance by maintaining estimated values of the original in situ effective stress throughout the sample preparation, ; instrumentation, and testing processes. As a result, the sample is not significantly unloaded, and therefore does not ; experience the stress-relief disturbance associated with the removal and re-application of stresses. ; This report documents design, development and validation work that has yielded a field-capable prototype DFSD tool ; that is capable of meeting or exceeding the best current laboratory testing capabilities for measurement of dynamic ; properties of clay soils used in earthquake site response analysis. Mechanical, pneumatic, electrical and sensor ; systems used to remotely create a test specimen, maintain continuous control of its anisotropic stress state, and test the ; specimen over a wide strain range of shear strain are described. Validation tests comparing DFSD results to state-ofthe- ; art laboratory results are presented as well as results from a series of tests that quantify and compare reduced ; sample disturbance caused by the DSFD relative to conventional high-quality sampling methods.
  More +
• Format:
  PDF
• Funding:
  65A0014 ; DRI Research Task No. 0024
• Download URL:
  https://rosap.ntl.bts.gov/view/dot/27577/dot_27577_DS1.pdf
• File Type:
  [PDF - 34.78 MB]
• Collection(s):
  US Transportation Collection
• Main Document Checksum:
  urn:sha256:245aef9a025e54b96c4d686ed3411cad1a0b96a280134078e542a148ad468ee6