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Analysis of Dynamic in Situ Backfill Property Tests. Report 1. A Method for Removing Oscillations and Damping from Diaphragm-Type Stress Gage Records.
HEBREW UNIV JERUSALEM (ISRAEL)
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A procedure for eliminating or minimizing the effects of stress gage frequency and damping has been developed. The method was applied to SE diaphragm stress gages used to measure soil stress during the passage of shock waves. The purposes of this study were to understand how stress records of diaphragm gages are related to imposed stress histories and to develop a method for deriving the stress histories from the records. Two-dimensional wave propagative simulations of embedded gages were made to determine the effects of the gage frequency characteristics on the gage record the results of these calculations showed that the gage filters the imposed stress like a single-degree-of-freedom oscillator would. Then a method was developed for deriving analytically a stress record corresponding to the response of an oscillator to an imposed stress history. This method was incorporated into an iterative procedure with which a user can construct a best estimate of a stress history acting on a diaphragm gage. This estimate is not necessarily the soil stress that would have existed in the absence of the gage. This record-processing procedure was used to compute stress histories for gages measuring vertical and horizontal stress in the DISKO-1 event executed by the US Army Engineer Waterways Experiment Station. Author
APPROVED FOR PUBLIC RELEASE