11 AUGUST 2020


Central Alliance, part of RSK Group, has launched Continuous Surface Wave (CSW) testing, allowing the company to provide a detailed, economic method of ground stiffness profiling, without the requirement for intrusive works.

Central Alliance’s CSW testing system uses a ‘vibrator’ with an operating range of 5-100Hz to produce surface or ‘Rayleigh’ waves, which propagate across the ground surface. These waves are detected by a system of geophones and software analysed to provide a stiffness vs depth profile. If required, office-based post-processing can provide shear wave velocity profiles, and subsequently mechanical properties of the ground such as shear modulus and elastic (Young’s) modulus.

CSW testing brings a number of benefits to all Ground Investigation (GI) contractors including rail and those in crane pad design as well as consultants offering a non-intrusive, portable and economic depth-profiling solution, compared with traditional ground profiling methods.

Specifically, Central Alliance’s CSW testing provision provides depth profiling up to 30m. It also delivers rapid results without invasive testing and enables the measurement of ground stiffness, comparable to results of CBR & SPT testing through the use of published research. Automated test software allows customisable testing for areas of interest and the equipment is lightweight and portable.

“The addition of CSW testing to the company’s portfolio of testing and surveying techniques greatly widens the options available to our clients in both the rail sector where this technique will find particular application, and the wider constriction industry. With CSW being portable, economic and non-invasive, as well as providing comparable results to CBR & SPT testing, its benefits will make a real difference to depth profiling applications.”
Craig White
Joint Managing Director