How to choose the right rotary drilling tools for you foundation project?

           The formations constructed by rotary drilling rigs are very different, and so it is also the technical requirements. Piling contractor select different drill bits to meet various construction requirements, so it is very 
  important to do a good job in the selection of rotary drilling rig bits.
           There are many factors that affect the selection of the tools for rotary drilling rigs. In summary, there are three main aspects: stratum conditions; drilling rig functions; specific requirements such as hole depth, 
  aperture, ballast thickness, wall protection measures, etc. Today let's study how the stratum affects the drill bit chose to use.
            The main function of the rotary drilling rig is to drill holes and grooves on the surface. The working object is the rock. Due to the shallow depth of the pile hole, the rock  would have undergone complex change 
  under the influence of the tectonic movement, natural mechanical, chemical effects, the structure, particle size, porosity, cementation status,  occurrence and compressive strength, etc. So the working object of the 
  rotary drilling rig is particularly complicated. In summary, there are the following categories.
            According to lithology (common), it can be divided into mud rock, sandstone, limestone, granite, etc.; according to its origin, it can be divided into igneous rock, sedimentary rock and metamorphic rock; 
  according to its mechanical properties, it can be divided into solid, plastic and loose.
           (1) Clay: Choose a rotary drilling bucket with a single bottom. If the small hole, you can use a two-petal bucket or a bucket with a cone plate.
           
           (2) For silt layer, weakly viscous soil layer, sandy soil, and pebble layer with relatively small cemented particles, it can be equipped with a double-bottomed drilling bucket.
           
           (3) Hard clay: choose a rotary drilling bucket with a single soil inlet (single and double bottoms are acceptable), or a straight auger with soil teeth.
           
         （4) Frozen soil layer: straight auger and rotary drilling buckets can be used for those with less ice content, and conical auger bits can be used for those with large ice content. It should be noted that auger bits
  are used for soil layers (desilting outside) are effective, but must be used in the absence of groundwater, so as not to produce suction and got stuck.
  
           (5) Consolidated pebbles and strongly weathered rocks: Conical auger bits and double-bottom rotary drilling buckets are required (single port for larger particle size and double port for small particle size)
           
           (6) Stroke bedrock: Equipped with core barrel bullet bit,conical auger ,double bottom rotary drilling bucket, or straight auger with bullet bit and double bottom drilling bucket.
           
           (7) Slightly weathered bedrock: Equipped with core barrel with roller bit,conical auger bullet bit,double bottom drilling bucket, if the diameter is too large, a graded drilling process should be adopted.

           After today's study, you may had knew clearly on how to select the tools for different formation.If you still have concern about it, welcome discuss with us.