since 2022, Geoptic has SURVEYED OVER 6km of tunnels in more than 60 OVERNIGHT shifts

Our innovative, non-contact and non-invasive approach provides a 3d view of the tunnel’s overburden

tunnel overburden imaging muon Survey Services

If you would like to arrange a time to discuss a survey in more detail, please fill in the tunnel survey enquiry form below

Background

Geoptic have an established standard overburden muon measurement service which is suitable for the majority of tunnels and underground structures.

The service comprises the deployment of one or more of our muon imaging systems into the structure to look upwards at the overburden. 

Our standard muon survey service is suitable for tunnels that are:

  • Shallower than 100m or 300 feet

  • Can be episodically or continually accessed over the measurement duration

For deeper depths, we can often design a bespoke survey, please get in contact to discuss your project further.

There are two variations of our standard tunnel surveys: The discovery and targeted surveys. In both types of survey, the survey will provide a density map of the tunnel overburden.

targeted tunnel surveys

The targeted survey utilises prior knowledge of a suspected feature above the tunnel. The goal of targeted surveys is to measure the density and/or size of the suspected feature. Examples include the measurement of the in-fill of a shaft or void, or the extent of the void or density anomaly.

Depending on the size of the targeted feature, a total length of survey can be estimated. In targeted surveys, the measurement points are more closely spaced at between 2.5m to 5m, every 30 to 60 minutes (depending on the depth). Again more muon survey systems can be deployed to reduce the overall time. 

For example, for a muon survey with the aim of understanding the in-fill of a shaft, a total length of around 30m would be surveyed. The total measurement time required would be around 6 to 12 hours (depending on depth).  As per the discovery muon survey, the targeted survey does not need to be continuous and could, for instance, be performed in two to four 3 hour periods across a number of days. 

discovery Tunnel Surveys

The discovery survey is suitable for tunnels where there is a exploratory need to establish the location of hazards in the overburden. 

This type of survey is sometimes called a portal-to-portal survey as the survey usually proceeds from one entrance to the other with measurement points at steps of around 5m to 10m apart.   

The required time for the muon survey varies according to the depth. Approximately a linear region of the overburden can be surveyed at a rate of 10m along the tunnel every 30 to 60 minutes for a single system.

The survey time through the tunnel can be significantly reduced by deploying more than one survey system. Presently, up to four systems can be deployed allowing a coverage of 40m every 30 to 60 minutes.

For instance, a discovery survey of a 400m long tunnel, in which four systems are deployed, will take around 5 to 10 hours of measurement time. If continuous access is not possible then the total measurement time can be taken episodically and combined later. 

The image above shows an overnight railway tunnel survey in which two systems were deployed in a targeted, closely-spaced arrangement. The team of three are monitoring the data as it is being acquired before moving on to the next positions for both muon systems along the tunnel.

The other images include: A survey of a disused tunnel in which the team are discussing the correlation of tunnel roof features with the incoming muon data; and a photograph of exiting a railway tunnel after an overnight muon survey.

contact us

Please feel free to fill in the form below to kindly give us a head start considering your project. If you would prefer, please feel free to use our short version instead.