Apparatus for directional boring under mixed conditions

Abstract

A drill head for an apparatus for horizontal directional drilling. The drill head includes a device for detecting angular orientation, a holder for the device for detecting angular orientation, the device for detecting angular orientation being disposed therein, a hammer driven by a liquid and a drill bit. The holder, the hammer and the drill bit are connected head to tail along a longitudinal axis of a drill string with the holder at a proximate end of the drill head and the drill bit at a distal end of the drill head.

Description

[0001]This application claims the benefit of U.S. Provisional Application No. 60 / 122,593, filed Mar. 3, 1999.TECHNICAL FIELD OF THE INVENTION[0002]The invention relates to directional boring and, in particular to a system for boring through both soil and solid rock using the same machine.BACKGROUND OF THE INVENTION[0003]At present, when underground utilities such as natural gas, potable water, or sanitary sewer pipes are placed in rock, trenches are excavated using large hard rock trenching equipment such as the Vermeer T-655, or possibly even shot using explosives. In these conditions, electric, telephone and cable TV lines are normally strung overhead along poles, mostly due to the difficulty and expense of placing them underground. Thus, in many situations, a solid rock formation will cause utility lines to be located above ground due to the difficulty of underground installation. Many such sites involve mixed conditions involving both a solid rock formation for part of the run a...

AI Technical Summary

Benefits of technology

The patent describes a method for directional boring in mixed conditions of soil and solid rock using a drill bit with an impact hammer. The method involves first boring straight in both soil and rock by pushing and rotating the drill head with the drill string and delivering impacts with the hammer. Then, the drill head is directed towards the cutting action of the gage tower by repeatedly pushing and rotating the bit over an angle less than a full rotation while delivering impacts with the hammer. This allows for better steering in some ground conditions. Additionally, delivering impacts with the hammer while changing direction in soil can provide better steering than just pushing the drill string alone.

Problems solved by technology

Since the main cutting face of the drill bit is large and flat, the pushing force of the drill string alone may be insufficient to steer the tool in soft ground without rotation.

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