Good vibrations: Continuous surface wave testing launched by Central Alliance

September 06, 2019

RSK company Central Alliance has launched a continuous surface wave (CSW) testing service so it can to provide an economic method of detailed ground stiffness profiling without intrusive work.

The CSW testing system uses a vibrating source with an operating range of 5 to 100 Hz to produce surface or Rayleigh waves that propagate across the ground. These waves are detected by a system of geophones and analysed using software to provide a stiffness versus depth profile. If required, office-based post-processing can provide shear wave velocity profiles and, subsequently, mechanical properties of the ground such as shear and elastic (Young’s) modulus. The automated test software enables customisable testing for areas of interest and the equipment is lightweight and portable.

CSW testing brings various benefits to a wide range of clients, including those operating in the rail sector. The test results are useful for crane pad design and for evaluating stiffness to a greater depth for foundation design. CSW testing provides a non-intrusive, portable and economic depth-profiling solution compared with traditional ground profiling methods.

Specifically, Central Alliance’s CSW testing service provides depth profiling to 30 m. It also delivers rapid results without invasive testing and enables the measurement of ground stiffness. The results are comparable to those from California bearing ratio and standard penetration testing according to published research.

Craig White, Central Alliance’s joint managing, director said, “The addition of CSW testing to the company’s portfolio of testing and surveying techniques greatly widens the options available to our clients in the rail sector, where this technique will find particular application, and the wider constriction industry. As the CSW equipment is portable, economic and non-intrusive and it provides comparable results to California bearing ratio and standard penetration testing, its benefits will make a real difference to depth profiling applications.”

For more information about Central Alliance’s CSW testing, call +44 (0)1924 229889 or email

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