Application of surface and borehole seismic methods to trenchless construction problems

Abstract

Within cities and urban areas trenchless construction and tunnelling are preferred methods for providing new infrastructure mainly because of their social and environmental benefits. However, problems can occur when unexpected subsurface conditions are encountered or when relatively 'minor' geotechnical factors interact with the construction process in unexpected ways that create adverse outcomes. These can cause extensive project delays, major cost over-runs and legal disputation. Advanced geophysical technologies using combinations of marine, land and borehole seismic methods can assist with identifying and overcoming geotechnical problems encountered during trenchless construction. Case studies from recent civil infrastructure projects in Australia and China demonstrate the application of various seismic methods to a range of trenchless construction problems. These projects involve horizontal directional boring, pipe-jacking and micro-tunnelling in soils, mixed material and rock for pipeline and buried power cable installations. The case studies clearly show that appropriate seismic methods can assist in the solution of construction problems of a geological or geotechnical nature. This provides a new application area for engineering geophysics.