Estimating base resistance and N value in rotary press-in

In the press-in method, press-in machines use static jacking force to install prefabricated piles, while gaining a reaction force by grasping several of the previously installed piles. The emergence of this piling technique in 1975 solved problems in urban piling construction such as noise and vibration associated with the piling work, restricted construction conditions due to the existing structures, and so on. Among a variety of press-in methods, rotary press-in is a relatively new technique to install tubular piles into hard ground by applying axial and rotational jacking force at the same time. An additional feature of the press-in Method is that it allows continuous measurement of penetration depth and jacking force during piling work. The concept of a PPT, Pile Penetration Test, has been developed to apply this feature to improving the efficiency of piling work and foundation design. This paper highlights the technique to estimate base resistance and N value from the data acquired during rotary press-in.