DE2634709A1 - Vertical drain hole with filter in ground - is lined with filter mat on boring and filled with granules - Google Patents

Abstract

The boring tool draws, while boring, behind it filter mat which forms bore lining. The boring tool stem is enclosed by a guide tube for the mat. When the hole is completed then granular material is fed into borehole through the boring tool assembly. This material reaches the borehole bottom first and moves upwards. The filter mat is separated from the guided tube and the mat forms cylindrical cover on borehole wall. The initially flat filter mat is formed on insertion. The vertical drains are made reliably and economically by tool system for boring and simultaneously borehole lining.

Description

Process for the production of vertical drainages

and apparatus for performing this method.

The invention relates to a method for producing vertical drainages, in which a borehole is first sunk and then with a granular filter medium is filled, as well as a device for performing this method.

To consolidate soils that are exposed to loads from structures such as Dams, dykes, Oross tank systems or the like are subject to subsidence it is common and necessary, vertical drainage in the form of mostly fine sand to be provided as a granular filter medium filled boreholes.

The diameters of the vertical sand drainages that have been customary up to now are in about 20 to 30 cm, such drainages with sand of grain sizes between 0.2 to 2 mm are filled and where the quantities of different grain sizes, d. H. not over 0.2 mm or 0.2 to 2 mm in one solid percentage relationship to each other. For such vertical drainage hitherto a minimum diameter of about 20 to 30 cm has been considered necessary because if a smaller diameter is selected, there is a risk of the drainage shearing off There is ground displacement during the settlement period. Preparing for one at choice a smaller diameter the backfill considerable difficulties, since the introduction of the fine sand into the borehole has usually been done manually, if necessary with the help of a funnel.

Brought a diameter below the dimensions given above additionally so far the risk of clogging of the drainage body due to the formation of impermeable deposits or by bridging with it, such deposits interrupting the flow of drainage also with the choice of the above specified usual diameter occur 7 s when filling, as general pale, done in portions with fine sand using a shovel.

When sinking vertical drainage, the usual diameter up to now there is a relatively large amount of cuttings that are sucked off the borehole or onto others Way must be removed.

There is also a relatively large amount of pressurized water to promote the Drilled material required, so that the drilling site even with suction of the drill material is relatively heavily muddy.

The need for filling sand is for the production of the vertical drainage of hitherto usual diameters considerably.

The invention is based on the object of a method and a device to carry out this procedure, in which this corresponds to the state of Technique inherent disadvantages are avoided and the production of vertical drainages can be made technically safer and more economical.

This task is essentially achieved with the method of the type mentioned above solved in that when sinking the borehole at the same time the borehole surrounding filter mat behind the drill bit by means of a drill pipe outside surrounding guide tube is guided down and that after reaching the required drilling depth through the borehole with filter gravel as a granular filter medium the drill pipe is filled from the bottom of the borehole upwards, the filter mat is separated from the guide tube and rests cylindrically against the borehole wall.

The invention has the particular advantage that the Use of the filter mat primarily by shearing off the vertical drainage Prevents floor displacement, whereby the filter mat prevents the resulting tensile forces records. The filter mat, which has a very large cavity volume, enables in addition, in connection with the pore volume of that formed by the bed of gravel Sand core has a total passage that is far above what has been usual up to now. Through this it is possible to choose the BohrlochdurchmeSser so that it is only about a third the previously usual diameter, even with this small borehole size the total passage at least that of the vertical ones commonly used up to now Sand drainage with a diameter of between 20 and 30 cm. In addition, fall due to the choice of the small drilling diameter during manufacture, only about a tenth of the cuttings loosened during the production of the usual sand drainage. The saving of filler gravel is significant. It becomes far less than a tenth of the filler material needed for backfilling sand drainages with diameters between 20 and 30 cm was required. The use of the filter mat also prevents that soil parts from the soil surrounding the vertical drainage into the gravel core get stuck there and render the drainage ineffective.

In addition to this filter effect, there is also the wicking effect exploited the filter mat, which consists in that Pore water is transported out of the loaded layers by means of the filter mat.

An advantageous embodiment according to the invention can thereby be created that the filter mat unwound as a flat web and through a Former cylindrically shaped is introduced into the borehole. This creates a extremely high flexibility when it comes to the depth of such drains.

In detail, the invention can be developed in that the cuttings are conveyed with pressurized water passed through the rods and that to increase the rate of ascent of the water loaded with cuttings between the guide tube and the drill pipe compressed air is pressed into the borehole.

This has the advantage that very little, i. H.

a minimum of pressurized water to run the vertical drainage receiving hole is required, so that the drilling site 'relatively little is polluted by water leakage and the associated sludge formation.

In an advantageous embodiment according to the invention, the Mixture consisting of pressurized water, cuttings and compressed air through the annulus between Borehole wall and guide tube brought to light outside the filter mat.

In particular, it can be advantageous to use the filling gravel in the injector method enter into the pressurized water flow and through the drill pipe to the bottom of the borehole to promote. Here it is particularly advantageous to adjust the speed of the pressurized water to be dimensioned in such a way that the filler gravel does not enter the annular space between the borehole wall and filter mat is promoted.

There is a particularly advantageous embodiment according to the invention in that the filter mat through the vortex-like guided, Pressurized water is uncoupled from the lower end of the guide tube.

The filling with filter gravel is advantageously carried out at the same time Tightening of drill rods and guide tube continuously up to the top of the borehole carried out.

Another object of the invention is a device for implementation of the method described above with a drill rod coupled to a power head with drill bit, with the drill pipe for pumping pressurized water to the bottom of the borehole is hollow, which is characterized in that a drill pipe outside surrounding guide tube is provided and that the guide tube in the area its lower end has a releasable attachment to which one from above in the drilled hole inserted filter mat can be fastened.

This device can experience an advantageous embodiment, that a magazine, in particular a role for the tracked in the form of a flat path Filter mat and a former, which is arranged above the surface and encompasses the guide tube is provided, which introduces the filter web cylindrically into the borehole.

In an advantageous further development of the device according to the invention an annular space is provided between the drill pipe and the guide tube, which with a Compressed air source is connectable.

A particularly preferred embodiment according to the invention has an injector-like connection for the filling of the vertical drainage serving gravel to the pressurized water supply of the drill pipe.

In the following the invention is exemplified with reference to one in the drawing illustrated embodiment explained in more detail.

It shows: Fig. 1 is a side sectional view of the device according to the invention; and FIG. 2 is a side sectional view of a finished one Vertical drainage according to the invention.

tie illustrated in Figure 1 is used for production by means of a Drill rod 5 with a drill bit 6 at its lower end a borehole 12 in the required depth sunk, the drill bit 6 is designed such that the bore hole is made larger in diameter than the drill string 5. For this purpose, the drill bit 6 consists of several radially pivotable cutting edges 13, which, however, pivot inwards about axes 14 when the drill rod is tightened can and thus when tightening the drill pipe within the diameter of the same lie.

Above the chisel is a guide tube surrounding the drill rod 5 3 is provided, which between the drill rod 5 and the guide tube 3 is an annular space 15 leaves free and is designed such that when tightening the drill rod 5 with is pulled up.

The guide tube 3 carries the filter mat surrounding it cylindrically 1, which is held with a releasable fastening 4 on this. The filter mat 1 is from a magazine, in particular a roll (not shown) continuously tracked during sinking and a funnel-shaped former 2 over days in the cylindrical shape in which it surrounds the guide tube 3. With 7, the borehole wall is also designated in FIG.

With the embodiment of the invention illustrated in FIG Device is a hole with a much smaller diameter than usual Pressurized water and air in the directional drilling process under simultaneous Introduction of the filter mat 1 into the borehole 12 as follows and sunk with filter gravel backfilled.

The drill bit 6 is in re-animal motion via the drill rod 5 offset. At the same time, pressurized water, which is indicated in Figure 1 by the arrows 8 is through a connection via the power head (not shown) of the device pumped through the drill pipe 5. In order to achieve a higher rate of ascent of the with Drilled cuttings-laden water in the annular space 16 between the borehole wall 7 and the guide tube 3 outside the filter mat 1 and around the same time with the smallest annular space Using as little pressurized water as possible is indicated by the arrows 9 in FIG 1 indicated, via a connection in the power head through the annular space 15 between Guide tube 3 and drill rod 5 compressed air pressed into the hole. compressed air and pressurized water occur loaded with cuttings in the annulus between the Filter mat 1 lined guide tube 3 and the borehole wall 7 at high speed revealed. In this way, the cuttings loosened from the drill bit are conveyed.

A magazine is in the form of the leader of the device according to the invention a roller (not shown) arranged in which a rolled up filter mat 1 is located. The filter mat 1 is at the lower end of the guide tube 3 before sinking the hole so attached that they resisted the Reibungswi when drilling Resists mud and is safely carried down to the bottom of the borehole but later on reaching the bottom of the borehole effortlessly from the retracted guide tube 3 can be solved and applied to the wall 7 of the borehole. During the above The drilling process is carried out over the filter mat 1, which is unwound as a flat web Days shaped cylindrically by the former 2. Press underground from the drill bit 6 exiting pressurized water 8, as well as from the gap between the drill rod and guide tube escaping compressed air 9, which is already cylindrically shaped filter mat 1 to the guide tube 3. The filter mat 1 is thus safe up to the required Depth led into the borehole. Pressurized water and compressed air come with the cuttings loaded in the annular space 16 between borehole wall 7 and filter mat 1 to light.

If the required drilling depth is reached, the Boreholes with filter gravel through the drill string 5 from the bottom of the borehole upwards, what is indicated in Figure 1 by the arrows 10, which is a mixture of water and filter gravel. The gravel is injected into the pressurized water flow entered and promoted through the drill string 5 to the bottom of the borehole. The speed of the pressurized water is dimensioned in such a way that the filler gravel does not return in the annulus can emerge. During the filling process, the guide tube 3 and the Drill rods 5 tightened continuously by means of the power head, not shown. The filter mat 1 is swirled by the exiting pressurized water from the lower The end of the guide tube 3 is separated and lies down during the filling process on the borehole wall 7 cylindrically. The water now occurs between the adjoining Mat and guide tube exposed, the filling with filter gravel is up to the top of the borehole continuously continued.

Figure 2 shows a sectional view of a finished vertical drainage according to the present invention, with 11 the finished gravel filling and with 17 the surrounding soil layers are designated.

As described above, the method according to the invention differs from the hitherto customary through the use of a cylindrical surrounding the gravel core Filter mat, the type of filling through the drill pipe from the bottom of the borehole upwards, as well as through the use of a relatively small borehole diameter, All the technical mentioned in the description and recognizable in the drawings Details are important to the invention.

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Claims (12)

PATENT CLAIMS 1,) Method for producing vertical drainage, in which a borehole is first sunk and then with granular filter medium is filled, characterized in that at the same time when the borehole is aborted a filter mat enclosing the borehole behind the drill bit by means of a the drill pipe surrounding the outside of the guide tube is guided downwards and that after reaching the required drilling depth the borehole with filter gravel as granular filter medium through the drill pipe from the bottom of the borehole upwards is filled, whereby the filter mat is separated from the guide tube and becomes cylindrical applied to the borehole wall. 2. The method according to claim 1, characterized in that the filter mat unwound as a flat web and shaped cylindrically by a former into the borehole is stirred in. 3. The method according to claim 1 or 2, characterized in that the Drilled material is promoted with passed through the rod pressure water and that for Increase in the rate of ascent of the water loaded with cuttings between the guide tube and the drill pipe compressed air is pressed into the borehole. 4. The method according to claim 3, characterized in that the from Pressurized water, cuttings and compressed air existing mixture through the annulus between Borehole and guide tube outside the filter mat is brought to light. 5. The method according to any one of the preceding claims, characterized in, that the filler gravel entered into the pressurized water flow in the injector process and through the drill pipe is conveyed to the bottom of the borehole. 6. The method according to claim 5, characterized in that the speed of the pressurized water is dimensioned such that the filler gravel does not enter the annular space between Borehole wall and filter mat is promoted. 7. The method according to any one of the preceding claims, characterized in that that the filter mat by the eddy-like pressure water guided from the lower end of the Guide tube is uncoupled. 8. The method according to any one of the preceding claims, characterized in, that the filling with filter gravel with simultaneous tightening of Bdhrgestänge and guide pipe is continuously passed up to the top of the borehole. 9. Device for performing the method according to one of the preceding Claims 1 to 8 with a drill rod coupled to a power head with a drill bit, wherein the drill string for the production of pressurized water to the bottom of the borehole is hollow is, characterized in that a guide tube surrounding the drill rod (5) on the outside (3) is provided and that the guide tube (3) in the region of its lower end a has releasable fastening (4), on which one is introduced into the borehole from above Filter mat (1) can be attached. 10. The device according to claim 9, characterized in that a magazine, in particular role for the filter mat (1) which is tracked in the form of a flat path and a former (2) arranged above the surface and encompassing the guide tube (3) is provided is, which introduces the filter web (1) cylindrically into the borehole. 11. Apparatus according to claim 9 or 10, characterized in that an annular space (15) is provided between the drill rods (5) and the guide tube (3), which can be connected to a compressed air source. 12. Device according to one of claims 9 to 11, characterized in that that an injector-like connection for filter gravel to the pressure water line (8) of the Drill rod (5) is provided.