Abstract
This paper describes measurement and interpretation of response of two, multiple story, older, urban structures to small charge weight, ultra-high frequency rock blast excitation from contiguous excavation. Time correlated responses were measured at the ends, top and bottom of the structures as well as in the foundation rock below the bottom. Observations based on the ten, instrumented positions during eight blast events provided over seventy time histories for analysis. The case study and measurements allowed the following conclusions: close-in blasting with direct rock to building wave transmission imposes short wave length excitation which fails to excite the large, massive structures synchronously. The structures respond predominantly in wave transmission mode where there is a noticeable difference in time, frequency, phase and amplitude of motions measured at the bottom and top corners of the structure. Excitation motions along the base also differ in time, frequency, phase and amplitude. The short wave length of the excitation motions leads to attenuation of the peak particle velocity along the base.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 54-63 |
| Number of pages | 10 |
| Journal | International Journal of Rock Mechanics and Mining Sciences |
| Volume | 111 |
| DOIs | |
| State | Published - Nov 2018 |
Funding
This paper is the result of an unusual set of fortuitous circumstances and the authors wish to acknowledge the organizations and special circumstances that allowed the writing of the paper. First, the New York City Fire Department for their interest in allowing this activity to further the science of blast vibration monitoring. Second, building owners and their contractors for their cooperation and coordination given the inevitable intrusions necessary to instrument structures in the midst of a complicated and compact construction foot print. Third, members of the Aimone-Martin Associates for installing and maintaining the instruments during the course of the investigation. Fourth, the GGGE Program of the CMMI Division of the National Science Foundation ,USA which provided the additional funds to time correlate the instruments through the RAPID Response initiative. Finally, the U.S. Embassy in Tunis as well as the U.S. Department of State, Bureau of Educational and Cultural Affairs and the Council for the International Exchange of Scholars for their assistance and support during the Fulbright Visiting Research Fellowship of Dr. Essaieb Hamdi at the Civil and Environmental Engineering Department of the Northwestern University.
Keywords
- Close-in rock blasting
- Deamplification
- High frequency excitation
- Peak particle velocity
- Spectral analysis
- Urban structures
- Wave propagation
- Wave transmission response
ASJC Scopus subject areas
- Geotechnical Engineering and Engineering Geology