Boring or penetrating the earth – With well-type screen
Reexamination Certificate
2001-02-15
2002-08-13
Bagnell, David (Department: 3672)
Boring or penetrating the earth
With well-type screen
C175S312000, C175S414000, C166S233000
Reexamination Certificate
active
06431292
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a device for drilling, in particular impact drilling or rotary percussion drilling, and draining holes in soil or rock material, wherein a drill bit mounted on a drill rod assembly forms a drill hole and a jacket tube is coupled with the drill rod assembly or the drill bit, wherein the jacket tube in the region following upon the drill bit is formed with at least one passage opening that opens into an annular space formed between the drill rod assembly and the jacket tube.
2. Description of the Prior Art
A device of this type can be taken, for instance, from WO 98/21439, wherein a process and a device for simultaneously drilling and lining holes is disclosed. By means of a jacket tube surrounded by a drill rod assembly actuating a drill bit, an annular space is made available between the jacket tube and the external periphery of the drill rod assembly, wherein, for instance, in the region immediately following upon the drill bit, at least one passage opening is provided in the jacket tube, via which worked material may subsequently be extracted from the drill hole to be produced. Furthermore, it is, of course, possible to extract from the drill hole, through that passage opening, also water present in the immediate region of the drill bit such that dewatering or draining of a bore hole may be effected in the foremost section in the region of the drill bit by that known device. However, when doing so, it is to be anticipated that selective dewatering or draining is impossible not least for the reason that the at least one passage opening provided in the region immediately following upon the drill bit serves to remove the worked material and, therefore, must have an accordingly large cross section naturally unable to provide for the respective filter effect required in draining.
A modified embodiment of a device of the type mentioned-above can be taken, for instance, from FR-A 2 543 213, wherein a drill rod is surrounded by a jacket tube and within the drill rod there is provided in the leading part a further tubelike component being provided with openings. Furthermore there should be provided a mat-like filtering element, for instance.
From U.S. Pat. No. 2,891,623 there has become known a device and a tool for providing and maintaining a respective filtering effect of a well, which differs essentially from the intended use and operation of a device according to the type mentioned-above. Similarily perforated tubes or elements for usage in the construction of a well can be taken from U.S. Pat. Nos. 3,221,819 and 4,869,323.
SUMMARY OF THE INVENTION
The present invention, thus, aims at providing a device of the initially defined kind, which renders feasible not only the drilling, in particular impact drilling or rotary percussion drilling, of a bore hole, but, if desired, additionally enables the selective dewatering or drainage of the rock material surrounding the drilling, in particular upon completion of the drill hole.
To solve this object, the device for drilling, in particular impact drilling or rotary percussion drilling, and draining holes in soil or rock material according to the invention, departing from a device of the initially mentioned kind, essentially is characterized in that the jacket tube, in the end region following upon the drill bit, is surrounded by at least one filtering tube formed with a plurality of passage openings or slits arranged distributedly about its circumference, particularly in a uniform manner and that the jacket tube is free of passage openings over a partial region, for instance about one third, of its circumference. Due to the fact that, according to the invention, besides the jacket tube, which is formed with at least one passage opening in the region following upon the drill bit, an additional filtering tube surrounding the jacket tube is provided, draining or dewatering of soil or rock material surrounding the drill hole is feasible both during the drilling procedure and also subsequent to the formation of a drill hole selectively and, in particular, over a large length of the drill hole. By arranging and forming as well as dimensioning the passage openings or passage slits in the at least one filtering tube in an appropriate manner, a suitable filter effect may be obtained, whereby only fluid to be drained after filtering is introduced into the annular space or clearance defined by the jacket tube and the drill rod assembly and removed from the drill hole. This filter effect over a large length of the drilling also may be maintained, for instance, after the removal of the drill rod assembly with parts of the drill bit. Due to the fact that according to the invention it is further provided that the jacket tube is free of passage openings over a partial region, for instance about one third, of its circumference, by arranging the passage-opening-free region of the jacket tube, which is subjected merely to tensile stresses and not to torsional stresses, in the lower region of the drill hole, it is thus prevented that fluid to be received and removed enters the upper region of the jacket tube and again leaves the interior of the jacket tube in the lower region such that the safe drainage of fluid present in the interior of the jacket tube will be ensured even with bores extending obliquely upwards.
In order to enable a substantially uniform filter effect over the entire periphery of the filtering tube as well as the jacket tube surrounded by the filtering tube, it is contemplated according to a preferred embodiment of the invention that the filtering tube surrounds the jacket tube while forming a further annular space.
In order to enable the proper passage through the filtering tube of the liquid to be drained, it is provided that the annular space formed between the external circumference of the jacket tube and the internal diameter of the filtering tube has a clear passage width of at least 1 mm and, in particular, about 1.5 mm, as in correspondence with a further preferred embodiment of the device according to the invention. Such a clear passage cross section or dimensioning of the annular space provided between the external circumference of the jacket tube and the internal circumference of the filtering tube usually will be sufficient to enable the proper drainage of the fluid to be drained into the interior of the jacket tube, while simultaneously ensuring that no excessive enlargement, or no enlargement at all, of the drill hole diameter or drill hole cross section will be become necessary during the production of the drill hole in order to take into account the additional dimensions of the jacket-tube-surrounding filtering tube to be inserted so as to avoid any additional extra expense for realizing a bore.
If the arrangement of one or several filtering tubes over a larger longitudinal extension of the jacket tube in the region following upon the drill bit is desired, it is, moreover, provided in a preferred manner that the annular space is defined by spacers arranged between the jacket tube and the filtering tube and/or by sleeve elements provided, in particular, in the end regions of the filtering tube such that the annular space required between the jacket tube and the filtering tube for a proper filter effect even over larger lengths of a filtering section will be safely maintained.
In order to prevent the annular space provided between the filtering tube and the jacket tube from being obstructed by worked rock eventually introduced along with the fluid to be drained, it is, moreover, suggested that the filtering tube over its circumference is formed with respectively equidistant passage slits each having a width of about 0.5 mm to about 1 mm, as in correspondence with a further preferred embodiment of the device according to the invention.
In particular, when providing a filtering tube having a larger longitudinal extension or when providing several contiguous filtering tubes in order to be able to provide an accordingly long draining or dewat
Bohm Karl
Mocivnik Josef
Bagnell David
Dougherty Jennifer R.
Jacobson & Holman PLLC
Techno Entwicklungs - und Vertriebs GmbH
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