Seismics

Ferroscan

Microgravity

Soil thermal resistivity / Soil thermal conductivity

BACK TO GEOPHYSICS

Contact Us

Other geophysical survey services:-

We also have expertise in the following techniques and can recommend them if the site suits:-

Seismic refraction / reflection:-

By imparting a large energy pulse into the ground using a hammer, drop weight or cartridge explosive a series of geophones are used to detect the seismic energy returning to the ground surface. The energy arrives at the geophones either directly along the ground surface, by reflection from layers or interfaces or by refraction from the top of a layer. Using the return time of the energy we can calculate velocity, model the presence of layers, and find ground stiffness and rippability. Using continuous surface waves (CSWS) generated by a vibrating mass it is possible to obtain ground stiffness profiles for geotechnical purposes within 50 minutes. The method can be used on contaminated land and difficult sites as it is non-intrusive.

Ferroscan rebar & reinforcement mapping :-

Although not usually classed as geophysics, the Hilti Ferroscan is used for the mapping of steel rebar and reinforcement mesh in concrete. The instrument gives an almost instant visual image - very useful for on-site decision making and concrete slab and column surveys

Microgravity:-

Measurements of local gravitational field can be taken with exceptionally sensitive instruments. By measuring the variation in gravity over a tight grid its possible to model the data to obtain information on the location of voids, infilled karst features, buried channels and buried structures. Although a relatively slow method due to the precise levelling needed between each survey station the output can be worthwhile since the system measures passively and is not affected by electrical or conductive interference and can be used in industrial buildings where vibration is kept to a minimum.

Soil thermal resistivity / soil thermal conductivity and buried cables:-

Cable engineers use measurements of soil thermal resistivity or soil thermal conductivity to design power cable installation schemes. A number of incidents have occurred in the past where the soil around a cable under high load was not able to conduct heat quickly enough to prevent thermal runaway and subsequent damage. We use the KD2 soil thermal resistivity / thermal conductivity probe to provide in-situ measurements of the soil thermal resistivity or thermal conductivity. The method can also used for obtaining the soil thermal properties before design and viability assessment of geothermal ground heat systems both domestic and industrial.

Soil electrical resistivity testing / earth resistance testing / soil electrical conductivity:-

To enable the design of earth grids at electrical installations such as substations, cable routes, wind farm projects and transmission towers, knowledge of the soil electrical resistivity or conductivity is often required using an appropriate earth resistance testing method. Typically soil electrical resistivity is measured using the 4 electrode Wenner resistivity technique and a suitable resistivity meter. A test point close to proposed earth grid installation is chosen or numerous measurements can be made along the proposed cable route. At each test point earth resistance measurements are taken by expanding the electrode spread to gain soil resistivity data in a depth profile or at a continuous depth. We can supply either raw soil resistivity data or can model the data to show how the soil resistivity changes with depth and differing layers of strata.

The measurement of soil electrical resistivity is also important along pipe routes to assess the potential soil corrosivity. Here measurements of soil resistivity are made at intervals along the pipe route at a depth corresponding to the installation depth. This can be achieved from the surface by using an appropriate electrode spacing to account for changes in the installation depth over the pipe route.