Patent Application
20190177943
The invention relates to an arrangement for introducing an elongate, flexible element, such as a drainage element, in particular a drainage ribbon, into a subsoil.
Such arrangements are for instance employed for consolidating a slack, water-bearing subsoil by stimulated or forced drainage. The drainage ribbons have a water transporting construction or composition and are vertically inserted into the subsoil, whereby the water is more rapidly drained upwards. The subsoil consolidates then more rapidly and the bearing strength of the subsoil increases.
It is common use to introduce drainage ribbons into the subsoil by means of a hollow mandrel that is kept upright by means of a king post and that is vertically driven into and out of the subsoil while leaving the drainage ribbon behind that is fed through the hollow mandrel. The end of the introduced drainage ribbon is initially anchored into the subsoil by means of an elongate push bar. The push bar extends through the entire mandrel to be operated by an hydraulic cylinder at the top of the mandrel.
In practice, the bottom end of the mandrel undergoes the most wear due to the friction with solid particles in the subsoil. When the bottom of the known mandrel has worn out, the entire mandrel is replaced. This requires that the push bar is drawn out of the entire mandrel, which can only be performed with the king post laying horizontally. Therefore in practice the replacement of the mandrel is avoided by employing for each new drainage project a mandrel that has well enough reserve for that project, as a replacement operation may last multiple working days and it is impractical to ship a new mandrel to the project area due to its length. The employment of mandrels with well enough reserve to be on the safe side implies that mandrels are decommissioned before the technical lifetime has passed. This is disadvantageous from a cost perspective.
It is an object of the present invention to provide an arrangement for vertically introducing an elongate, flexible element into a subsoil by means of a hollow mandrel, wherein the technical lifetime of the mandrel can be optimized.
According to a first aspect, the invention provides an arrangement for vertically introducing an elongate, flexible element, such as a drainage element, in particular a drainage ribbon, into a subsoil, comprising a king post and an elongate hollow mandrel that is slideably guided along the king post in its longitudinal direction between a retracted position in which the mandrel extends above the subsoil and an extended position in which the mandrel penetrates the subsoil, wherein the elongate, flexible element is fed through the hollow mandrel, wherein the mandrel comprises a permanent section and respective replacement section at the end of the mandrel, wherein the permanent section comprises a first elongate and hollow mandrel profile and a mandrel drive, and wherein the replacement section comprises a second elongate and hollow mandrel profile that is attached to the end of the first mandrel profile, a bottom face at the bottom end of the second mandrel profile, a push bar that is slideably guided inside the second mandrel profile in its elongate direction between a retracted position with respect to the bottom face and an extended position in which it projects downwards from the bottom face, and a spring that biases the push bar towards its extended position, wherein the mandrel drive comprises an hydraulic drive cylinder that is mounted to the first mandrel profile, and a drive cable that extends through the hollow mandrel and that is at one end operatively connected with the hydraulic cylinder and that is at the opposite end operatively connected with the push bar by means of a releasable coupling.
The mandrel of the arrangement according to the invention comprises a permanent section and a respective replacement section of which the mandrel profiles are attached to each other. When the replacement section has worn out, it suffices to lift the vertical king post just enough to expose the transition between these sections. The replacement section can then be removed by separating the replacement section from the permanent section and by releasing the releasable coupling with the drive cable. Thereafter a same new replacement section can be installed by operatively connecting the drive cable to it by means of the releasable coupling and by attaching it to the permanent section. During this operation the drive cable hangs slack inside the permanent section. This replacement operation can be performed quickly by human operators during a drainage project, whereby the technical lifetime of the mandrel can be optimized. In this regard it is to be understood that the term ‘permanent section’ means that this section can be attached to multiple subsequent replacement sections before it will be decommissioned.
In an embodiment the second mandrel profile is attached to the end of the first mandrel profile by means of a weld, which forms a strong attachment that can only be released by cutting.
Alternatively the second mandrel profile is attached to the end of the first mandrel profile by means of bolts.
In an embodiment the drive cable and the elongate, flexible element extend parallel and adjacent to each other inside the hollow mandrel. As the drive cable is under tension it does not hamper the passage of the elongate, flexible element through the mandrel. The first mandrel profile and the second mandrel profile can thus be relatively slim when compared to prior art mandrels in which the elongate, flexible element need to be kept separated from the deflecting push bar over the entire length of the mandrel.
In an embodiment the replacement section comprises a first guide body inside the second mandrel profile behind the bottom face, wherein the first guide body is provided with a hole through which the push bar slideably extends.
In an embodiment the replacement section comprises a second guide body inside the second mandrel profile spaced apart from the bottom face, wherein the second guide body is provided with two holes through which two parallel slide rods extend that are connected to the push bar, and two push springs that extend around the slide rods and that are biased between the second guide body and the push bar.
In an embodiment thereof the drive cable extends between the slide rods.
In an embodiment the releasable coupling is located between the slide rods.
In an embodiment the replacement part comprises a cylindrical steel rod that is transversely attached to the push bar, wherein the replacement part comprises semicircular recesses that merge into the bottom face and that receives the cylindrical rod in the retracted position of the push bar. The end of the elongate, flexible element is released when the cylindrical rod is pushed out of the recess.
In an embodiment the arrangement comprises a steel guide profile along the king post in which the mandrel is slidably confined, wherein the guide profile comprises an elongate slot along its length and wherein the mandrel drive comprises a drive flange that project from the first mandrel profile and through the elongate slot, wherein the hydraulic drive cylinder is mounted to the drive flange and extends outside the guide profile. As the hydraulic drive cylinder extends outside the first mandrel profile and the guide profile, the first mandrel profile and the second mandrel profile can be relatively slim with respect to prior art mandrels.
In an embodiment the replacement section has a length that is less than one-fourth, preferably less than one-fifth of the entire length of the mandrel.
According to a second aspect, the invention provides a method for operating an arrangement for vertically introducing an elongate, flexible element, such as a drainage element, in particular a drainage ribbon, into a subsoil, wherein the arrangement comprises a king post and an elongate hollow mandrel that is slideably guided along the king post in its longitudinal direction between a retracted position in which the mandrel extends above the subsoil and an extended position in which the mandrel penetrates the subsoil, wherein the elongate, flexible element is fed through the hollow mandrel, wherein the mandrel comprises a permanent section and respective replacement section at the end of the mandrel, wherein the permanent section comprises a first elongate and hollow mandrel profile and a mandrel drive, and wherein the replacement section comprises a second elongate and hollow mandrel profile that is attached to the end of the first mandrel profile, a bottom face at the bottom end of the second mandrel profile, a push bar that is slideably guided inside the second mandrel profile in its elongate direction between a retracted position with respect to the bottom face and an extended position in which it projects downwards from the bottom face, and a spring that biases the push bar towards its extended position, wherein the mandrel drive comprises an hydraulic drive cylinder that is mounted to the first mandrel profile, and a drive cable that extends through the hollow mandrel and that is at one end operatively connected with the hydraulic drive cylinder and that is at the opposite end operatively connected with the push bar by means of a releasable coupling, wherein the method comprises vertically introducing a series of elongate, flexible elements into the subsoil by penetrating the subsoil with the mandrel and retracting it while leaving the introduced elongate, flexible element behind, wherein after introducing the series of elongate, flexible elements the replacement section is separated from the permanent section and the releasable coupling is released, and another replacement section is installed by operatively connecting the drive cable with the push bar by means of the releasable coupling and by attaching the replacement section to the permanent section. The method according to the invention can be performed during an operational project by operators on the subsoil, for example between subsequent introducing strokes of the mandrel and right at the moment that the replacement section has worn out in its entirety.
In an embodiment thereof the replacement section is separated from the permanent section by cutting and is attached to the permanent section by welding.
In an embodiment the releasable coupling is released by hand or by means of a hand tool.
In an embodiment the king post is kept vertically upright during the replacement of the replacement section while the drive cable remains extending through the permanent section of the hollow mandrel.
The various aspects and features described and shown in the specification can be applied, individually, wherever possible. These individual aspects, in particular the aspects and features described in the attached dependent claims, can be made subject of divisional patent applications.
The invention will be elucidated on the basis of an exemplary embodiment shown in the attached drawings, in which:
As schematically shown in
As best shown in
The upper drive flange 31 and the lower drive flange 34 are positioned spaced apart from each other, wherein the flanges 31, 34 are interconnected with two side plates 37 that carry two pulleys 38, 39 in between. The mandrel drive 30 is provided with a steel drive cable 40 of which the upper end 41 is connected to a lug of the lower drive flange 34 via an adjustable cable tensioner 42. The drive cable 40 runs along a drive pulley 44 at the end of an hydraulic drive drive cylinder 45 that is connected to a lug 46 of the upper drive flange 31, and subsequently along the pulleys 38, 39 between the side plates 38 into the first mandrel profile 21.
The replacement section 23 comprises a second mandrel profile 25 with the same cross section as the first mandrel profile 21, and a bottom face 26 in which an elongate slot 27 is provided. At the ends the slot 27 is bounded by semicircular recessions 28 in de smallest side walls of the second mandrel profile 25, and at one longitudinal side the slot 27 comprises a shorter rectangular side extension 29. Straight above this side extension 29 the replacement section 23 comprises a steel internal first guide body 52 with a rectangular slot 53 through which a steel push bar 54 is slidably guided. At the bottom side a steel cylindrical rod 55 is welded against the push bar 54. The release mechanism 50 comprises two parallel steel slide rods 56 that slideably extend through guide holes 57 in a steel internal second guide body 58 inside the second mandrel profile 25. The slide rods 56 are welded to a steel push body 59 that is welded to the top side of the push bar 54. The push body 59 comprises a lug 61 with an eye 62 between the slide rods 56. Two push springs 64 extend around the slide rods 56 and are biased between the second guide body 58 and the push body 59.
As shown in
As shown in
As shown in
As shown in
In operation of the arrangement 1, sections of drainage ribbons 90 are subsequently inserted in the subsoil 100. The operation starts with the mandrel 20 fully retracted and the hydraulic drive cylinder 45 retracted. The drainage ribbon 90 that is fed through the mandrel 20 is positioned such that the end projects from the bottom face 26. Subsequently the hydraulic drive cylinder 45 is retracted in direction B whereby the cylindrical rod 55 is firmly engaged within the semicircular recessions 28. In this position the elongate slot 27 in the bottom face 26 is closed off by the cylindrical rod 55 while the drainage ribbon 90 is firmly engaged. Subsequently the winch 71 is powered whereby the mandrel 20 penetrates the subsoil 100. In this stroke multiple soil layers 101, 102 may be penetrated until the soil layer to be drained is reached. At the end of the penetration stroke the hydraulic drive cylinder 45 is retracted whereby the push springs 64 push the push bar 54 and the cylindrical rod 55 out of the bottom face 26. Depending on the resistance of the subsoil, the cylindrical rod 55 further penetrates the subsoil or the cylindrical rod 55 remains at this depth while the mandrel 20 is retracted again in direction A. In both cases the drainage ribbon 90 is anchored, whereby it remains vertically in the subsoil when the mandrel 20 is fully retracted. Finally the drainage ribbon 90 is cut off above the subsoil 100 by means of the knives 115, 117 and a new penetration cycle starts.
The mandrel 20 is subject to substantive wear due to the friction with solid particles in the subsoil 100. In particular the replacement section 23 undergoes the most wear as it travels the longest distances into the subsoil 100. When the replacement section 23 has worn out, a transverse cut 64 is made in the mandrel 20 near the weld 24, preferably in the first mandrel profile 21, and subsequently the pin 65 is pulled out whereby the coupling with the drive cable 40 is released. The drive cable 40 remains hanging downward through the remainder of the mandrel 20. Subsequently a new replacement section 23 is installed by coupling the drive cable 40 by mean of the pin 65 and by welding it to the permanent section 22 of the mandrel 20. The exchange of replacement sections 23 can be executed even during a drainage project, as is can be performed quickly and safely by human operators on the subsoil 100 while the king post 7 remains vertical upright.
It is to be understood that the above description is included to illustrate the operation of the preferred embodiments and is not meant to limit the scope of the invention. From the above discussion, many variations will be apparent to one skilled in the art that would yet be encompassed by the scope of the present invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2016988 | Jun 2016 | NL | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/NL2017/050406 | 6/19/2017 | WO | 00 |
