Boring (earth)

This may be done for prospecting to identify and quantify an ore body for mining, or to determining the type of foundations needed for a building or raised structure, or for underground structures, including tunnels and deep basements where an understanding of the ground is vital to determining how to excavate and the support philosophy.

Han dynasty China (202 BC – 220 AD) used deep borehole drilling for mining and other projects.

Soft ground drilling can be undertaken using a rotary auger or wash boring techniques, while rock drilling often use methods such as NMLC which allow for recovery of a core of material which can be examined to determine the strength, degree of weathering, understanding of any how intact the rock is (RQD) and identify any discontinuities or other planes of weakness.

In rock in-situ stress testing using hydrofracturing or overcoring, Acoustic Televiewer can be used to map discontinuities to determine their orientation.

In 1961 the United States began Project Mohole, an ambitious attempt to drill through the Earth's crust into the Mohorovičić discontinuity.

As the drill bits burnt out and were removed for replacement, the hole simply flowed closed, and the rock had to be re-drilled.