Drilling apparatus, method, and system

Abstract

A helical drag bit provided with spirally / helically positioned cutting arms. The arms can create a spiral trench geometry in the sidewall of a predrilled pilot hole. The cutting arms can terminate in scoring cutting blades. The helical drag bit can be incorporated into a system and method for measuring geo-tech characteristics. The helical drag bit can be used in a system and method for improving the holding capacity of rock bolts and similar devices for use in the mining industry or in any circumstances where a particulate substrate may benefit from support. Novel rock bolts having new structures can be used with this improved hole geometry or may form such improved hole geometry.

Description

[0001] This application claims the benefit of U.S. provisional patent application No. 60 / 496,379, filed Aug. 20, 2003, the entirety of which is hereby incorporated by reference.BACKGROUND [0002] 1. Field of the Invention [0003] The invention relates to helical drag bits and rock bolt systems, which can be used for geotech, mining, and excavation purposes. The invention also relates to methods of using such helical drag bits, and systems incorporating such helical drag bits and rock bolts. [0004] 2. Related Art [0005] Known drilling systems may employ roller cone bits, which operate by successively crushing rock at the base of a bore. Roller cone bits are disadvantageous because rock is typically resistant to crushing. Other known rock drilling systems employ drag bits. Conventional drag bits operate by shearing rock off at the base of the bore. Drag bits can be more efficient than roller cone bits because rock is typically less resistant to shearing than to crushing. [0006] Most sta...

AI Technical Summary

Benefits of technology

[0024] The helical drag bit can be used in a system and method for improving the holding capacity of rock bolts and similar devices for use in the mining industry or in any circumstances where a particulate substrate may benefit from support. The helical drag bit can produce an improved rock bolt hole geometry, which can interact with mechanical or chemical holding means to improve pull-out capacity in the support structure. Conventional as well as novel rock bolts (having new structures) can be used with this improved hole geometry. Such novel rock bolts can incorporate the helical drag bit design or can excavate a rock bolt hole in a similar way.

Problems solved by technology

Roller cone bits are disadvantageous because rock is typically resistant to crushing.

These cutting actions result in a noisy work environment coupled with the undesirable excitation vibrations that are transmitted to the drill unit home structure.

A problem encountered by geologists or other rock mechanics investigators is the difficulty of obtaining accurate compressive strength measurements of rock in the field, particularly in situ during drilling.

In the mining industry, roof falls in coal mines continue to be the greatest safety hazard faced by underground coal mine personnel.

Notwithstanding the importance of these other factors, if the rock bolts used in rock stabilization do not perform well, miners are at risk.

Bolt installation characteristics near roof falls have been identified as contributing to failure.

One documented and regularly occurring rock bolt failure mechanism is loss of grout shear bond to the rock wall of the bolt hole.

However, even with these variations in bolt hole smoothness, anchorage capacity increases, but failure of the rock-grout interface is still common.

While considerable research into rock bolting has been conducted to date, gaps still exist in areas that could lead to vast improvements in rock bolt performance.

Other problems are also encountered in the field of rock bolt hole drilling: dust and noise.

While significant research into dust hazards and health effects has been conducted by NIOSH (and previously by the U.S. Department of Interior, Bureau of Mines), the measures to improve the environment for rock bolt drillers has been limited almost entirely to worker protection actions.

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