Seismic Measurements of Ground Displacements Caused by Trains and Quarry Blasts at the Superconducting Super Collider Site in Texas

Abstract

Ground vibrations caused by cultural noise sources such as road traffic, trains, and quarry blasts can significantly affect sensitive scientific experiments and manufacturing processes. When constructing a facility that requires ultra-stable ground conditions it is prudent to first measure the level of background noise at the proposed site. In this study, seismic measurements are used to measure near-surface ground vibrations at the superconducting super collider (SSC) site in the state of Texas. The SSC is an oval shaped ring, which is [Formula: see text] in circumference. A design limit of the SSC is that the ground vibrations should be less than [Formula: see text] [Formula: see text] in amplitude. Seismic measurements of ground velocity were made, both at the surface and within boreholes, at several sites around the proposed SSC ring. Through a series of data processing steps the ground velocity measurements were transformed into ground displacements. Ground displacements caused by quarry blasts were sufficiently small at the SSC ring such that they posed no problem for the design and operation of the SSC. However, ground displacements caused by trains at railroad crossings significantly exceeded the displacement tolerance level of the SSC design. Furthermore, the peak amplitude in the spectra of the measured ground velocity shifted from [Formula: see text] near the railroad tracks to [Formula: see text] far from the tracks [Formula: see text]. The peak ground displacements, however, occurred at frequencies less than [Formula: see text] in both the near-field and far-field measurements. If the SSC construction had continued, it would have been necessary to either re-engineer the train tracks and railroad crossings to reduce the amount of ground vibration or to re-route the trains around the SSC ring. In August 1993, however, the United States Congress ordered the Department of Energy to halt construction on the multi-billion dollar SSC project.