What equipment should be used for drilling in strongly weathered formation

What is a strongly weathered rock formation?

Strongly weathered rock stratum is not a kind of rock, but a weathering level formed by various genesis rocks under the action of solar radiation, atmosphere, water and biology. Such as igneous rocks (strongly weathered granite), sedimentary rocks (strongly weathered sandstone) and metamorphic rocks (strongly weathered gneiss), etc.

Because of the strong weathering rock stratum fissures are very developed, so it is not suitable for uniaxial compressive strength test. Usually, the ultimate bearing capacity (kPa) is used as the strength unit of strongly weathered rocks in geological reports, and the strength of strongly weathered rocks is generally between 300 kPa and 750 kPa.

What equipment should be used for drilling in strongly weathered geology

(1) The drilling rig is equipped with a friction or interlocking kelly bar, which can meet the pile diameter and pile length.

2. Kelly Bar: choose the type of drill pipe according to the strength of the strongly weathered rock (1 meter pile diameter, for example), the ultimate bearing capacity is lower than 500 kPa with friction kelly bar; higher than 500 kPa with interlocking kelly bar.

3. Drilling tools: Most of the strongly weathered rocks can be drilled with a double-bottom bucket of bullet teeth; double-cone spiral drilling tools can also be used for dry drilling. When the ultimate bearing capacity rises to 600 kPa–900 kPa, it is necessary to use a cartridge drill for ring cutting, but it is impossible to take cores, so it is necessary to use double-bottom crushing again.

4. Drilling teeth: 30/50.22 mm bullet teeth and 4S bullet teeth guide teeth are used to drill into the strong weathering, which is conducive to crushing, reducing drilling resistance, and effectively reducing losses.