This is the continuation of previously discussed predrilling and problem arises for driving piles in saturated plastic clay in providing pile foundation. So far we know about heaving of surrounding structures and piles. Piling in this type of soil results another problem as follows.
Sometimes lateral movements also associated with driving action. This problem is severe in unstable slope near the pile driving site. The severity reach extreme condition, when an existing excavation work or excavated site extends below pile driving level.
Dear reader we have published some posts regarding excavation safety. You can read this post for further information in relation to safety issues for excavating a foundation site.
Another problem arises where a composite pile is used as foundation pile. The heaving action sometimes releases the connection of joint bet two separate piling materials that comprises a complete pile.
So far we learned about problems of driving pile in such type of soil. Now we will learn how we can get rid of these situations. Where objections are coming from surrounding sites, slope failure is concerned, redriven produced extra cost and inconvenience to contractor, a method of removing part of soil from the space which is to be occupied by the pile. These method perform fairly good to avoid above situations.
In this purpose usually a predrilling is done with auger, sometimes rotary cutting equipment with the action of water jets. This method of cutting with jet transforms the problem soil, clay into heavy slurry. Dear reader this procedure of drilling is called predrilling.