Drill Rigs Come in a Variety of Shapes and Sizes (Essay Sample)

A drilling and sampling program's goal is to collect samples that accurately reflect subsurface conditions over the entire project site. The type and frequency of sampling is determined by the sort of material encountered as well as the investigation's goal. Additional extensive information can be found in the American Association of State Highway and Transportation Officials' (AASHTO) Manual on Subsurface Investigation. Continuous sampling, when used correctly, gives the most full and accurate data.
PROCEDURE AND DISCUSSION
Types of Drill Rigs
Drill rigs come in a variety of shapes and sizes. Large truck-mounted rigs, also known as highway rigs, off-road track-mounted rigs, and trailer-mounted portable rigs are among the most prevalent. Different rigs are best suited for various site circumstances and drilling and sample techniques. The Large Truck Mounted Rig is the most adaptable and popular rig, but it can only be utilized in situations where it can be driven onto the job site.
Process of Drilling and Sampling
The first stage is to set up a rig above the area where we want to drill. The drilling boom or pole is then erected and checked for verticality. The drilling and sampling process are carried out by a drill head positioned on the boom. Drilling was made easier by the drill head's two motions. Drill bits can be rotated with a torque, and drill bits and other equipment can be raised and lowered with a vertical thrust. To explore subsurface conditions, we can utilize a variety of drilling and sampling techniques.
Open Hole Method
Continuous flight augers, which mechanically dig and continuously deliver cuttings to the surface, or solid stem augers (SSA). Augers come in diameters ranging from 3 to 14 inches. There are several advantages to solid stem augering. It creates moderate number of readily contained cuttings, and the drilling operation requires little orno fluid. The use of thin-walled and split-barrel sampling is encouraged. Smaller drill rigs can be used for solid stem augering because the torque requirements are reduced. This makes site navigation easier and typically results in lower expenses. This drilling process, however, has a number of drawbacks. The solid stem augermust be removed from the hole in order to retrieve soil samples. As a result, this method is only applicable to stable soils that will not collapse after the augers are withdrawn. Because the augers must be removed from the hole during each sampling procedure, soil sampling during solid stem auger drilling is time consuming, especially in deeper holes.
Hollow Stem Auger Method
Hollow stem augers (HAS) are typically used to install groundwater monitoring wells for environmental and geotechnical purposes, but they can also be used to collect soil samples. Continuous flight augers with huge diameters (up to 14-inch outer diameter) are used in hollow stem auger drilling to mechanically dig and deliver cuttings to the surface. To excavate the center of the bore, a center bit attached to the drill rod and bolted to the auger driving cap is inserted through the cutter head. Sections of drill rod are added as the boring progresses by adding sections of auger, keeping the center bit at the face of the cutter bit. There are several advantages to hollow stem augering. During and after the drilling process, the augers serve as a temporary casing. This makes soil and water sampling and monitoring well installation easier. The drilling procedure is relatively quick, and little or no fluid is required. This drilling approach also works well for thin-walled and split-barrel samples. Hollow stem augering has a number of drawbacks. Drilling in poorly lithified to unlithified sediments, for example, is restricted. It can only go down to a depth of 150feet. This depth could be greatly reduced by shallow bedrock or other difficult-to-drill materials. When drilling a borehole, high hydrostatic pressures can cause sand to heave up into the auger, causing complications with soil sampling and well installation.