The detection of abandoned mineshafts by railway track bed using transmitted seismic waves using broadside shot gathers

The practical challenges of mineshaft detection under railway embankments are discussed, together with typical mineshaft properties over the centuries. The paper focuses on the broadside shot seismic transmission method to detect abandoned mineshafts, with the potential to be used in the vicinity of embankments. A numerical model was developed, using a new type of absorbing boundary condition, which is referred to as the Recursive Integration Perfectly Matched Layer. From a series of simulations using this model, a series of practical outcomes were identified regarding the feasibility of the broadside seismic transmission method. These include the layout of the geophones, the frequency of the shot source together with ways of improving the signal to noise ratio. The results from a field trail in East Lothian, Scotland are compared with the output from the numerical model and good agreement was identified.