Method of extending augered pile cavity through rock or like obstruction

Abstract

Method for forming concrete columnar body in an earth situs including rock formation. First, a hollow shafted auger is drilled in the earth until rock is encountered, and then a percussion or rotary rock drill is axially operated through the hollow shaft of the auger to drill a cavity extension in the rock formation. Hardenable fluid cement mortar is fed into the cavities to form columnar body with elongated rigid means axially centered to be anchoringly positioned in formed columnar body.

Description

BACKGROUND OF INVENTION

In Lee A. Turzillo, U.S. Pat. No. 3,604,214, methods and means is disclosed variously utilizing auger within an auger equipment, as for producing sand drains and cast-in-place concrete pile bodies in the earth of a situs. While said patent discloses a highly satisfactory method and means for producing a concrete column in an earth situs, with a tie-rod or a tension element anchored thereto, no method or means is specifically disclosed for expeditiously doing so under conditions where a rock formation is encountered in the downward path of the earth augering equipment.

SUMMARY OF INVENTION

In use of the method and means of the present invention, as for producing a concrete column in an earth situs containing a rock formation with a tie-rod or tension element centered in the column, a relatively large auger is initially drilled into the earth to define therein a cavity of requisite large diameter, and until the inner end of the large auger shaft, or a bit or closure member at the inner end of the shaft, encounters a rock formation, at which time the drilling is stopped. While retaining the large auger in the stopped position a clear passage is provided through the shaft thereof and a rock drill on the end of a hollow shaft, generally referred to by the trade as a "Kelley-bar," may be lowered through the auger shaft until cutting teeth on the rock drill encounter the rock formation. With use of known rotary or percussion methods, the rock drill is operated to cut into the rock and thereby form therein a hole of requisite depth, and of smaller diameter than the cavity formed in the earth.

The drilled rock particles may be removed from the hole drilled in the rock in various ways, including by jetting water and/or air down the rock drill shaft to convey the rock particles up along the space between the rock drill and the wall of the auger shaft, to be disposed of at the upper end of the auger shaft in known manner. A tie-rod, tension member, or elongated reinforcing means may be placed down the rock drill shaft, to extend to the bottom of the rock cavity. The rock drill then may be withdrawn from the rock cavity while feeding fluid self-hardening cementitious material through the rock drill shaft, progressively to fill the rock cavity around the rod or like means centered in the rock cavity. As an alternative to this procedure, however, the fluid cementitious material may be pumped through the auger shaft, into the rock cavity, after withdrawal of the Kelly-bar and after said placement of a tie-rod, tension member, or elongated reinforcing means to extend into the rock cavity.

Next, and subsequent to withdrawal of the rock drill into the hollow shaft of the large auger, the large auger may be rotated in screwing direction to remove the earth retained in flighting of the same, and thereby to form the larger earth cavity. Simultaneously with gradual withdrawal of said auger a similar self-hardenable cementitious material may be pumped or fed, either down the auger shaft or through the rock drill shaft, progressively to fill the formed earth cavity to requisite upward extent, to have a tie-rod, tension member or reinforcing means, anchoringly centered therein.

An object of the present invention is to provide a method and means for forming a concrete columnar body in an earth situs, including provision of an effective and efficient way to continue installation of the columnar body to requisite effective depth upon encountering rock formation in the earth situs.

Another object of the invention is to provide a method and means of the character described utilizing a hollow-shafted auger and a rock drill affixed on a shaft operable through the auger shaft, and by which a rock cavity can be accurately drilled in a manner capable of serving as a guide passage for ready retraction of the rock drill from the rock cavity upwardly into the auger shaft.

Other objects of the invention will be manifest from the following brief description and the accompanying drawings.

Of the accompanying drawings:

FIG. 1 is a fragmentary vertical cross-section, partly broken away, of the lower end of an auger within an auger which has been drilled into the earth of a situs to define a cavity therein before encountering a rock formation.

FIG. 2 is a fragmentary cross-section corresponding to FIG. 1, illustrating a condition in which a hollow-shafted rock drill has been operated axially through the hollow shaft of the larger auger to drill a cavity of selective depth in the rock formation to be aligned with the passage through the auger shaft, and also illustrating positioning of an elongated rod through the hollow drill shaft.

FIG. 3 is a view corresponding to FIG. 2, but with the large auger and the rock drill removed from the situs, and after steps of feeding self-hardening cementitious material into the rock cavity and the larger earth cavity with elongated rod anchoringly positioned therein.

FIG. 4 is a bottom end view of the rock drill bit, illustrating centered aperture means therein for passage of the elongated rod from the drill shaft into the drilled cavities.

Referring to FIG. 1, the apparatus 10 suitable for practicing the method of the invention, to produce a concrete pile body, initially may include a relatively large, continuous flight hollow-shafted, sectional auger 11 adapted to be rotatably mounted on a vertically movable carriage (not shown) of a drilling rig of known type. Initially, as for forming a pile cavity L in the earth situs E, the hollow shaft 11 of auger 12 may have a smaller auger 13 axially and rotatably received therein, to be axially operated to move a bit or closure member 14 between open and closed positions as for passage of material to or from the pile cavity. A suitable drilling rig for variously using this auger within an auger type of drilling equipment is exemplified in Turzillo U.S. Pat. No. 3,604,214.

In the event that the large auger 12, in drilling the cavity C in the earth E, encounters a rock formation R further drilling movement of auger 12 is withheld, and a small auger 13 is replaced by a rock drill 15, affixed on the lower end of a hollow shaft 16, and is in turn operated to rotate the bit 15 against the rock formation to drill a rock cavity S of desired or predetermined depth as shown in FIG. 2. The rock cuttings may be removed from the rock cavity S during drilling, as by force feeding fluid and/or air into the rock cavity, to drive such cuttings up the auger shaft 11, in known manner.

After said removal of the rock cuttings, the rock drill may be withdrawn, without rotation, while feeding self-hardenable fluid cementitious material, such as cement mortar, either through the drill rod 16 into the rock cavity until the rock drill is withdrawn into the auger shaft 11 or through the auger shaft after removal of the drill rod therefrom. Withdrawal of the rock drill from the rock cavity into the auger shaft 11 may be facilitated by the bit 15 having a plurality of cutting blades 15.sub.a, 15.sub.a each provided with a straight, radially outwardly presented, edge 17 of substantial axial extent which by engagement with the rock cavity wall during withdrawal of the drill 16, serves to guide the bit 15 axially into the auger shaft 12. The auger 12 may then be simultaneously axially withdrawn and rotated, in screwing direction, thereby to remove the augered earth from the earth cavity L while simultaneously filling the same with self-hardenable cementitious material to form a unitary concrete column 20, anchored to and supported by the rock formation R. Either prior to, during, or after withdrawal of the rock drill 15, as described, a tie-rod, tension element, or other rigid elongated member 21 may be placed or dropped through the rock drill shaft 16, or the auger shaft 11, as the case may be, subsequently to be axially centered in the pile body R, for strong anchoring connection thereto, as shown in FIG. 3, upon hardening of said cementitious material.

When the presence of a rock formation in the earth situs is known in advance, and the auger 11 has cutting teeth on its inner end, the rock drill or Kelley-bar 15 can be rotated with the auger until the rock formation is engaged by the rock drill cutters 15.sub.a. The rock drill would then be operated as previously described to drill down through the rock, ahead of the auger, to form the rock cavity S for grouting in steel or like metal uprights, tie-backs, tension members, and the like.

Modifications of the invention may be resorted to without departing from the spirit of the invention or the scope of the appended claims.

Claims

What is claimed is:

1. A method of forming a pile or like column in an earth situs including a rock-like formation, comprising the steps of screwing a hollow-shafted, spiral-flighted auger axially into the earth of the situs to drill a cavity therein to a depth encountering the rock formation; operating a hollow-shafted rock drill through the hollow shaft of the auger, with a drill bit presented inwardly, to drill a cavity extension of selective depth and given diameter in the rock formation; applying fluid pressure means within the rock cavity to remove the drilled rock cuttings therefrom through the auger shaft; withdrawing the rock drill through the auger shaft; such hollow shaft of such rock drill having an outer diameter substantially less than the inner diameter of the auger shaft, and such drill bit including peripherally spaced rock cutting blades and guide means including axially extending edges on the blades of substantial axial extent having an outer diameter slightly less than the inner diameter of such auger shaft which engage the rock cavity wall and extend into the auger shaft during withdrawal of the rock drill to guide the drill bit from the cavity extension axially into the hollow shaft auger; and feeding pressurized, self-hardenable, fluid material into the cavity and cavity extension to form a columnar body.

2. A method as in claim 1, wherein the hollow shaft of the rock drill and drill bit have a passage therethrough of a size for insertion of an elongated reinforcement member therethrough, further comprising the step of inserting such elongated reinforcement member through such passage in such rock drill and drill bit after the rock drill has drilled the cavity extension and before withdrawal of the rock drill therefrom, such elongated reinforcement member being left in the cavity extension and cavity and embedded in the columnar body after withdrawal of the rock drill and auger.

3. A method as in claim 1, wherein during screwing of the hollow-shafted auger axially into the earth of the situs to drill a cavity therein to a depth encountering the rock formation, a closure closes the lower end of the hollow-shafted auger, and when the rock formation is encountered, the closure is removed from the hollow-shafted auger to permit the hollow-shafted rock drill to be operated through the hollow shaft of the auger as aforesaid.

4. A method as in claim 3, wherein such closure is attached to a smaller auger axially and rotatably received in the hollow shaft of the auger during the auger drilling for moving the closure between open and closed positions.