Seismic Design of Tunnels - Parsons Brinckerhoff

1.0 INTRODUCTION
1.1 Purpose
The purpose of this research study was to develop a rational and consistent seismic
design methodology for lined transportation tunnels that would also be applicable to other
underground lined structures with similar characteristics. The results presented in this
report provide data for simple and practical application of this methodology.
While the general public is often skeptical about the performance of underground
structures, tunnel designers know that underground structures are among the safest
shelters during earthquakes, based primarily on damage data reported in the past. Yet
one certainly would not want to run away from a well designed building into a buried tunnel
when seismic events occur if that tunnel had been built with no seismic considerations.
Most tunnel structures were designed and built, however, without regard to seismic
effects. In the past, seismic design of tunnel structures has received considerably less
attention than that of surface structures, perhaps because of the conception about the
safety of most underground structures cited above. In fact, a seismic design procedure
was incorporated into a tunnel project for the first time in the 1960s by PB engineers.
In recent years, however, the enhanced awareness of seismic hazards for
underground structures has prompted an increased understanding of factors influencing
the seismic behavior of underground structures. Despite this understanding, significant
disparity exists among engineers in design philosophy, loading criteria, and methods of
analysis.
Therefore, this study, geared to advance the state of the art in earthquake engineering
of transportation tunnels, has the following goals:
• To maintain a consistent seismic design philosophy and consistent design criteria
both for underground structures and other civil engineering facilities.
• To develop simple yet rational methods of analysis for evaluating earthquake effects
on underground structures. The methodology should be consistent for structures with
different section geometries.
3