An improved method for the real time calculation of soil resistance during driving

The limited time between two successive blows during pile driving has resulted in the development of simple methods to calculate the soil resistance real time. These methods are called direct methods like the Case (Goble) method and Impedance method. Other more time consuming methods are called indirect methods, which are in most cases based on signal matching techniques like TNODLT. For several years now TNO applies a direct method called the TNO method. The driving resistance is calculated in a similar wav as for the Case and Impedance method. however the calculation of shaft and toe resistance is different. The damping parameters used by the TNO method have a closer relation with geotechnical practice and soil dynamics. The Case, Impedance and TNO method are described and are applied to a practical case.