Standard Penetration Test (SPT) N values are used to estimate static and dynamic properties of soil for foundation design and seismic liquefaction evaluations. SPT N values are controlled by amount of energy delivered to count N values. In USA and Europe, SPT hammer energy is measured below the hammer (i.e above the ground level) and used to correct N values. In other countries including India, hammer energy measurement is not part of the SPT procedure. Hence, a reliable energy correction is not available. N values are measured below ground and hammer energy is measured above ground. Prof. P. Anbazhagan, Department of Civil Engineering and his team have developed a new SPT – Hammer Energy Measurement Apparatus (SPT – HEMA) to measure the energy close to the sampler i.e below ground.
SPT – HEMA is a battery-operated portable system comprising of instrumented rods, signal conditioners, and power supply, high speed DAQ with customized software for conducting field test, data processing and post analysis. Presently, it is difficult to reproduce SPT N values and check quality of the N values after field testing is completed. SPT- HEMA does digital recording of N values and energy measurement at each blow count. These recordings can ensure reproducibility of N values in any soil investigation, quality control of field test and ensure reliable design parameters estimation.
For more information about SPT HEMA
Photo Credits – Mr. Haridasan