Process of Core Drilling 

Core drilling is a drilling method used to obtain samples of rock or soil from the subsurface of the earth. It is commonly used in geotechnical and geological investigations, as well as in the mining and construction industries. The process of core drilling typically involves the following steps:

.     Site preparation

Before drilling can begin, the site must be prepared. This may involve clearing the area of any vegetation or debris, marking out the drilling location, and setting up any necessary safety measures. The site must also be surveyed to determine the precise location of the drilling, as well as to identify any potential hazards or constraints that may affect the drilling process.

b.     Drilling rig setup

 The drilling rig, which is a large, heavy-duty machine used to drill the hole, is set up on the site. The rig typically consists of a drill string (a series of interlocking pipes), a drill bit (a cutting tool used to drill through the ground), and a power source (such as a hydraulic motor or diesel engine). The drill string is made up of several sections of pipe that are connected together and is typically several hundred feet long. The drill bit is attached to the bottom of the drill string and is typically made of tungsten carbide or another hard, durable material. The power source drives the rotation of the drill bit, and may also be used to raise and lower the drill string.

c.     Drilling works

The drill bit is lowered into the ground and rotated at high speeds to drill through the soil or rock. As the drilling progresses, the drill string is gradually lowered into the hole. A special drilling fluid, called "mud," is used to cool the drill bit and to flush out any cuttings (bits of soil or rock that are removed during the drilling process). The mud is pumped down the center of the drill string and out through the drill bit, where it cools the bit and carries the cuttings back to the surface. The cuttings are collected in a mud pit or tank, where they can be examined to provide information about the subsurface conditions.

d.     Core recovery

As the drill bit reaches the desired depth, a core barrel (a long, hollow tube) is attached to the drill string. The core barrel is used to extract a cylindrical sample of rock or soil from the hole, known as a "core." The core is typically several inches in diameter and several feet long. The core barrel is designed to rotate as the drill string is turned, which helps to prevent the core from breaking as it is extracted from the hole. The core is typically recovered in a long, continuous column, although it may be broken into shorter segments if necessary.

e. Core Analysis

Once the core has been extracted, it is typically analyzed to determine the geotechnical properties of the soil or rock. This may involve laboratory testing to determine the strength, density, and other properties of the material. The results of the core analysis can be used to inform the design and construction of foundations, underground structures, and other projects that rely on subsurface conditions.

In conclusion, Core drilling is a complex process that requires specialized equipment and trained personnel. It is often used in conjunction with other methods, such as geophysical surveys, to provide a more complete understanding of the subsurface conditions at a site.