Tunnel Location by Gas Flow
Abstract
Defense Advanced Research Agency (DARPA) has funded a program to improve capabilities to detect existing, hidden tunnels. Systems, Science and Software investigated both the seismic and gas flow characteristics of the rocks surrounding a test mine. Gas injection measurements showed communication by both pressure rise and arrival of tracer gas between the two boreholes from the surface on one side of the mine. The initial results made cross-borehole measurements of gas flow or liquid flow seem a promising method for detection of hidden tunnels. If a tunnel is between an injection point and a measurement hole, the high pressure flow would go preferentially into the tunnel rather than communicating to the other borehole. Measurements along a line of boreholes spaced much more modely than a tunnel diameter should be useful as a validation testing for tunnel detection. Field experiments determined the rates of gas flow from boreholes, through a fractured igneous rock, to a tunnel. Laboratory experiments showed that acetylene-oxygen mixtures would detonate in a 0.005-inch crack. It appears feasible to locate tunnels by injecting an explosive gas or liquid mixture into a nearby borehole and initiating an explosion in the tunnel from a borehole. A passive seismic network would be used to locate the explosion source.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 15, 1979
- Accession Number
- ADA151114
Entities
People
- D. R. Grine
- P. L. Lagus
- T. H. Pierce
Organizations
- Utility Systems Science and Software (United States)