The application of core barrel with roller cutting bit  in deep foundation

With the continuous popularization of rotary drilling applications, the diameter of the drilled holes is getting larger and deeper, and the depth is getting deeper and deeper. The use of rotary drilling in hard formations is also more and more common. How to improve the efficiency of rotary drilling and reduce construction costs is a technical problem that the rotary drilling industry needs to focus on. Manufacturers of rotary drilling tools have done a lot of research work in terms of drill bit structure, type and construction technology , and have developed a variety of drill bits and process methods for hard rock drilling, such as core barrel with bullet teeth, drilling auger, core barrel with roller bit, and compound drilling tools among them. In terms of construction drilling method, using the characteristics of rotary drilling rig bit replacement and easy tripping, a combination of drilling tools is used, that is, firstly the barrel drill is used to obtain the annular groove, then the auger bit is used to break the core rock, and finally the sand bucket is drill out the broken stone. 

The graded drilling method is used for large-diameter hard rock drilling, first use a small-diameter barrel to drill with a core barrel, and then drill with larger simple core barrel for reaming.Using air lift reverse circulation for full-section cone or hob drilling method; use air reverse circulation for down-the-hole hammer drilling, etc. These techniques have achieved good results for rotary drilling to deal with hard rock formations, and played a role in promoting the wide application of rotary drilling technology.