Current status of design and construction of piles with a pilot hole

When piles are designed and constructed in the field, a pilot hole, which is a type of pile driving assistant method that prepares a hole before installing the pile, is often adopted to aid the installation process where the existence of hard or stiff layers is expected. This is to mitigate or prevent damage to the pile during the installation process, as well as to ensure the pile reaches the required minimum tip elevation. A conventional pile driving process can also cause excessive vibration or noise during the installation. With pile driving assistant methods, a pile can be installed with greater ease when being inserted and seated on the bearing layer. Many state agencies have been using similar installation methods even though the names and specifications are different. This study presents a summary on the current guidelines for pile driving assistant methods that use a pilot hole adopted by different states and identifies challenges to improve the reliability and stability of the piles constructed with a pilot hole.