CA1153213A - Procedure and means for creating a vertical drain - Google Patents
Procedure and means for creating a vertical drainInfo
- Publication number
- CA1153213A CA1153213A CA000379519A CA379519A CA1153213A CA 1153213 A CA1153213 A CA 1153213A CA 000379519 A CA000379519 A CA 000379519A CA 379519 A CA379519 A CA 379519A CA 1153213 A CA1153213 A CA 1153213A
- Authority
- CA
- Canada
- Prior art keywords
- insertion tube
- drain
- prefabricated
- prefabricated drain
- cutting
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Abstract
Mauno Olavi Juhola Professor Pohjoiskaari 15 00200 Helsinki 20 Procedure and means for creating a vertical drain ABSTRACT OF DISCLOSURE
A procedure for creating a vertical drain by pushing into the ground an insertion tube housing within itself a so-called prefabricated drain, by pulling out the insertion tube and cutting off the prefabricated drain. The prefabricated drain is out off with a cross-cutting means located within the insertion tube at such height, or in such a layer as for instance a sand stratum which accepts the water conveyed by the prefabricated drain.
A procedure for creating a vertical drain by pushing into the ground an insertion tube housing within itself a so-called prefabricated drain, by pulling out the insertion tube and cutting off the prefabricated drain. The prefabricated drain is out off with a cross-cutting means located within the insertion tube at such height, or in such a layer as for instance a sand stratum which accepts the water conveyed by the prefabricated drain.
Description
llS~
.
The present invention i9 applied when using prefabricated drains to the purpose of compacting water-carrying, fine-grained and poorly water-per-meable 90il, such as clay, silt, etc. by carrying out dewatering of thesoil material with the aid of vertical draining and thereby reducing the water content of the soil material. Hereby one improves the bearing ca-pacity of the ground and accelerates the settlings that can be expected to take place, while at the same time the shearing strength of the 90il in-creases .
Various kinds of prefabricated drains have been developed for verticaldraining, consisting of a profiled strip e.g. of plastic with about 10 cm width, and of porous paper or another similar, draining material wound around it which i9 permeable to water.
A prefabricated drain is installed in the ground by pushing it with the aid of a special insertion tube to desired depth, usually in vertical direction. The prefabricated drain i9 held in the insertion tube, and the lower end of the prefabricated drain becomes snchored in position ~ith the aid of a special anchoring member. The insertion tube is pulled out on completed installation, thus leaving the vertical prefabricated drain in the ground. The prefabricated drain i~ cut off a short distance over the ground surface. Such prefabricated drains are provided at a suitable spacing depending on the ground conditions and on the objective in mind, e.g. with 1-2 m spacing, in the area which one desires to compact. The water from the soil material drains through the porous paper into the passages in the prefabricated drain, rises to the ground surface and runs off.
A procedure of this kind is indicated when the layer which has to be dried/compacted, e.g. a clay stratum1 lies on the ground ~urface or olose thereto. Often, however, the clay bed is overlaid by coarser, readily water-conducting 30il in the natural state or by earth filline, such as sand or gravel. It would not be nece3sary in such cases to rai~e the water from the clay bed all the way up to the eround surface: lifting the water into the sand layer over the clay cour~e would be fully enough.
The same situation is also encountered when vertical draining is used to dry, to compact, a clay and mud layer on the bottom of a sea or lake and ,,,",,, :' r?~ ~ 3 which may have a thickness of tens of ~etres. Vertic~l draining i9 re-quired when the intention is to fill up e.g. a la`~e or sea at the point in que3tion for the construction of a road, railway or aven an air field. If the soft, compressible clay or mud layer is not vertically drained prior to the filling operation, the settling of the compressible strata under effect of the earth fill and other loads imposed on them ta'~es many decades. The settling can be accelerated by vertical draining so that it i8 accomplished within a year or two, or even in a few months, depending on the subsoil conditions and the spacing of the vertical drains. Depend-ing on the 80il conditions and on the load, the settling may amount to several metres. When nowadays prefabricated drains are used towards the vertical draining of clay and mud layers, the procedure is to extend the prefabricated drains from the solid bottom through the clay course up to the water surface, where they are cut off.
The purpose of the present invention i8 to further develop the procedure known in the art. Thus the object of the invention i3 a procedure for creating a vertical drain by pushing into the soil an insertion tube housing in its interior a prefabricated drain, by pulling out the inser-tion tube and by cutting off the prefabricated drain. The invention i8 characteriæed in that the prefabricated drain is cut off with the aid of a cross-cutting means located within the insertion tube, at such height, or ir, such a layer as for instance a sand layer, which accepts the water conveyed by the prefabricated drain.
Certain remarkable advantages are gained by the aid of the invention.
Since the top e~d of the prefabricated drain is located at a level loYer than known heretofore, the hydrostatic pressure counteracting the flow in the prefabricated drain i9 correspondingly reduced, while at the same time the internal resistance to flow (the well resistance) in the vertical drain will be less~ This accelerates the flow in the prefabricated drain and improves the operability of the drain. On the other ha~d this also implies that less prefabricated drain material is required, which as a rule comes in rolls. Assuming for in~tance that the area that has to be provided with vertical drains is 10 hectare3, that the spacing of the prefabricated drains is 1.5 m and that it is possible to save 5 m of the length of each prefabricated drain, the total savings in the area will then be 220,000 metres of prefabricated drain.
--2~
`
~15~
The invention al80 concerns a mean~ for carrying out the procedure just described. ~he means is characterized in that it compri~es, located within the tube, a cutting blade movable in a direction tran~versal to the tube, and a counterblade located opposite to this first bla~e, and the prefab-ricated drain being located between these blades.
Fig. 1 illustrates the situ~tion which i8 pre~ent when the prefabricated drains are inserted, from dry land, into a clay or mu~ layer.
Fig. 2 illustrates a situation in which the prefabricated drains are in-serted in the clay or mud layer, operating on the water surface.
Fig. 3 shows the section alore the line III-III in Fig. 1.
Fig. 4 shows the section along the line IV-IV in Fig. 3.
Fig. 5 is equivalent to Fig. 4 and presents another embodiment of the in-vention.
FiB. 1 illustrates the case that there is, lowermoat, the hard bottom 1, thereupon a clay course 2, and upon this there i9 water-permeable natural soil or earth fillins 3, which lets water pass through. The installation of the prefabricated drains 9 takes place with the aid of an insertion tube 7 mounted on a working machine 32 moving on the ground surface 10.
While the insertion tube is in its top position, whereby its lower end 33 is above ground, the prefabricated drain 9 obtained from a ~torage coil 6 is affixed to the lower end of the ins_ertion tube. The insertion tube 7 is then pushed through the layers 3 and 2 all the way to the hard bottom 1. The lower end of the prefabricated drain 9 is secured to the hard bottom 1 with a special anchorin~ device (not depicted). ~he insertion tube is pulled up enough to bring the cross-cutting means in the tube a small distance over the top of the clay layer 2. The prefabricated drain 9 is cut off and the insertion tube raised to its top position. The working machine 32 is then sliehtly displaced, and another prefabricated drain 9 is introduced into the clay layer 2.
The cros3-cutting means within the insertion tube 7 is located close to .
`Y~ ;3 the lo-~er end of the insertion tube so that it is easily acces3ible for servicing, repairs or replacement.
Fig. 2 illustrates the case in which the prefabricated drains 9 are in-stalled in a clay course 2 in the bottom of a water body, such as a sea for instance, with the aid of a worXing mschine ~2 floating on a pontoon 8. The operation is similar to th~t described in connection with Fig. 1.
It is possible, before the operation is commenced, to deposit on the sea bottom a water-permeable sand cou.se 3. After the prefabricated drains 9 have been instslled, the earth filling 30 is run into the sea. It is moreo~er possible to cart an excess embankment 31 upon the earth filling, to speed up the settling. In the embodiment of Fig. 1 an excess embankment 31 may likewise be added.
Fig. 3 shows the cross section of the insertion tube 7 at the point where the prefabricated drain cross-cutting means is located. The cross-cutting means comprises a cylin~ body 12 with three cylinders 13 transversal to the insertion tube 7. The cylind~r body 12 carries on its bottom a cutting blade 14, transversal to the insertion tube 7. Each cylinder 13 is guided on a stationary piston 15 affixed to the wall of the insertion tube 7. Each cylinder 13 has been connected to a pressure fluid-carrying tube 11 entering through the top end of the insertion tube 7. ~hen pressure fluid i9 admitted into the cylinders, the cylinder body 12 will move to the right in Figs 3 and 4. Hereby it will push the prefabricated drain 9 against the counterblade 16 and cut ths prefabricated drain off. Both ends of the bottom of the cylind~r body 12 are acted on by a spring 17, which returns the cutting blade into its initial position as soon as the cylinders 1~ are depressurized. The cutting blade protector 18 and the counterblade protector 19 protect the prefabricated drain 9 durin6 the pulling up of the insertion tube 7.
In the embodiment of Fig. 5, the cutting blade 20 is journalled by its ends to be carried by two opposite -~alls of the insertion tube 7. For cross-cutting the prefabricated drain 9, the cutting blade 20 i8 rotated from the position shown in Fig. 4, clockwise, through about 90 degrees, whereby it meets the counterblade 21 and cuts the prefabricated drain. The cutting bladb 20 carries on its end a sprocket wheel 22 cooperating with a chain 11 entering the insertion tube 7 through its top end. The members 24, 25, 2v an~ 27 serve to protect the prefabricated drain 9 while the insertion tube 7 is being pulled up.
It i9 obvious to a person skilled in the art that different embodiments of the invention may vary within the scope of the claims stated below. This concerns, above all, the construction of the cross-cutting means within the in~ertion tube 7 and its mode of operation. This means may operate mechanically, hydraulically,.pneumatically o- electrically.
.
The present invention i9 applied when using prefabricated drains to the purpose of compacting water-carrying, fine-grained and poorly water-per-meable 90il, such as clay, silt, etc. by carrying out dewatering of thesoil material with the aid of vertical draining and thereby reducing the water content of the soil material. Hereby one improves the bearing ca-pacity of the ground and accelerates the settlings that can be expected to take place, while at the same time the shearing strength of the 90il in-creases .
Various kinds of prefabricated drains have been developed for verticaldraining, consisting of a profiled strip e.g. of plastic with about 10 cm width, and of porous paper or another similar, draining material wound around it which i9 permeable to water.
A prefabricated drain is installed in the ground by pushing it with the aid of a special insertion tube to desired depth, usually in vertical direction. The prefabricated drain i9 held in the insertion tube, and the lower end of the prefabricated drain becomes snchored in position ~ith the aid of a special anchoring member. The insertion tube is pulled out on completed installation, thus leaving the vertical prefabricated drain in the ground. The prefabricated drain i~ cut off a short distance over the ground surface. Such prefabricated drains are provided at a suitable spacing depending on the ground conditions and on the objective in mind, e.g. with 1-2 m spacing, in the area which one desires to compact. The water from the soil material drains through the porous paper into the passages in the prefabricated drain, rises to the ground surface and runs off.
A procedure of this kind is indicated when the layer which has to be dried/compacted, e.g. a clay stratum1 lies on the ground ~urface or olose thereto. Often, however, the clay bed is overlaid by coarser, readily water-conducting 30il in the natural state or by earth filline, such as sand or gravel. It would not be nece3sary in such cases to rai~e the water from the clay bed all the way up to the eround surface: lifting the water into the sand layer over the clay cour~e would be fully enough.
The same situation is also encountered when vertical draining is used to dry, to compact, a clay and mud layer on the bottom of a sea or lake and ,,,",,, :' r?~ ~ 3 which may have a thickness of tens of ~etres. Vertic~l draining i9 re-quired when the intention is to fill up e.g. a la`~e or sea at the point in que3tion for the construction of a road, railway or aven an air field. If the soft, compressible clay or mud layer is not vertically drained prior to the filling operation, the settling of the compressible strata under effect of the earth fill and other loads imposed on them ta'~es many decades. The settling can be accelerated by vertical draining so that it i8 accomplished within a year or two, or even in a few months, depending on the subsoil conditions and the spacing of the vertical drains. Depend-ing on the 80il conditions and on the load, the settling may amount to several metres. When nowadays prefabricated drains are used towards the vertical draining of clay and mud layers, the procedure is to extend the prefabricated drains from the solid bottom through the clay course up to the water surface, where they are cut off.
The purpose of the present invention i8 to further develop the procedure known in the art. Thus the object of the invention i3 a procedure for creating a vertical drain by pushing into the soil an insertion tube housing in its interior a prefabricated drain, by pulling out the inser-tion tube and by cutting off the prefabricated drain. The invention i8 characteriæed in that the prefabricated drain is cut off with the aid of a cross-cutting means located within the insertion tube, at such height, or ir, such a layer as for instance a sand layer, which accepts the water conveyed by the prefabricated drain.
Certain remarkable advantages are gained by the aid of the invention.
Since the top e~d of the prefabricated drain is located at a level loYer than known heretofore, the hydrostatic pressure counteracting the flow in the prefabricated drain i9 correspondingly reduced, while at the same time the internal resistance to flow (the well resistance) in the vertical drain will be less~ This accelerates the flow in the prefabricated drain and improves the operability of the drain. On the other ha~d this also implies that less prefabricated drain material is required, which as a rule comes in rolls. Assuming for in~tance that the area that has to be provided with vertical drains is 10 hectare3, that the spacing of the prefabricated drains is 1.5 m and that it is possible to save 5 m of the length of each prefabricated drain, the total savings in the area will then be 220,000 metres of prefabricated drain.
--2~
`
~15~
The invention al80 concerns a mean~ for carrying out the procedure just described. ~he means is characterized in that it compri~es, located within the tube, a cutting blade movable in a direction tran~versal to the tube, and a counterblade located opposite to this first bla~e, and the prefab-ricated drain being located between these blades.
Fig. 1 illustrates the situ~tion which i8 pre~ent when the prefabricated drains are inserted, from dry land, into a clay or mu~ layer.
Fig. 2 illustrates a situation in which the prefabricated drains are in-serted in the clay or mud layer, operating on the water surface.
Fig. 3 shows the section alore the line III-III in Fig. 1.
Fig. 4 shows the section along the line IV-IV in Fig. 3.
Fig. 5 is equivalent to Fig. 4 and presents another embodiment of the in-vention.
FiB. 1 illustrates the case that there is, lowermoat, the hard bottom 1, thereupon a clay course 2, and upon this there i9 water-permeable natural soil or earth fillins 3, which lets water pass through. The installation of the prefabricated drains 9 takes place with the aid of an insertion tube 7 mounted on a working machine 32 moving on the ground surface 10.
While the insertion tube is in its top position, whereby its lower end 33 is above ground, the prefabricated drain 9 obtained from a ~torage coil 6 is affixed to the lower end of the ins_ertion tube. The insertion tube 7 is then pushed through the layers 3 and 2 all the way to the hard bottom 1. The lower end of the prefabricated drain 9 is secured to the hard bottom 1 with a special anchorin~ device (not depicted). ~he insertion tube is pulled up enough to bring the cross-cutting means in the tube a small distance over the top of the clay layer 2. The prefabricated drain 9 is cut off and the insertion tube raised to its top position. The working machine 32 is then sliehtly displaced, and another prefabricated drain 9 is introduced into the clay layer 2.
The cros3-cutting means within the insertion tube 7 is located close to .
`Y~ ;3 the lo-~er end of the insertion tube so that it is easily acces3ible for servicing, repairs or replacement.
Fig. 2 illustrates the case in which the prefabricated drains 9 are in-stalled in a clay course 2 in the bottom of a water body, such as a sea for instance, with the aid of a worXing mschine ~2 floating on a pontoon 8. The operation is similar to th~t described in connection with Fig. 1.
It is possible, before the operation is commenced, to deposit on the sea bottom a water-permeable sand cou.se 3. After the prefabricated drains 9 have been instslled, the earth filling 30 is run into the sea. It is moreo~er possible to cart an excess embankment 31 upon the earth filling, to speed up the settling. In the embodiment of Fig. 1 an excess embankment 31 may likewise be added.
Fig. 3 shows the cross section of the insertion tube 7 at the point where the prefabricated drain cross-cutting means is located. The cross-cutting means comprises a cylin~ body 12 with three cylinders 13 transversal to the insertion tube 7. The cylind~r body 12 carries on its bottom a cutting blade 14, transversal to the insertion tube 7. Each cylinder 13 is guided on a stationary piston 15 affixed to the wall of the insertion tube 7. Each cylinder 13 has been connected to a pressure fluid-carrying tube 11 entering through the top end of the insertion tube 7. ~hen pressure fluid i9 admitted into the cylinders, the cylinder body 12 will move to the right in Figs 3 and 4. Hereby it will push the prefabricated drain 9 against the counterblade 16 and cut ths prefabricated drain off. Both ends of the bottom of the cylind~r body 12 are acted on by a spring 17, which returns the cutting blade into its initial position as soon as the cylinders 1~ are depressurized. The cutting blade protector 18 and the counterblade protector 19 protect the prefabricated drain 9 durin6 the pulling up of the insertion tube 7.
In the embodiment of Fig. 5, the cutting blade 20 is journalled by its ends to be carried by two opposite -~alls of the insertion tube 7. For cross-cutting the prefabricated drain 9, the cutting blade 20 i8 rotated from the position shown in Fig. 4, clockwise, through about 90 degrees, whereby it meets the counterblade 21 and cuts the prefabricated drain. The cutting bladb 20 carries on its end a sprocket wheel 22 cooperating with a chain 11 entering the insertion tube 7 through its top end. The members 24, 25, 2v an~ 27 serve to protect the prefabricated drain 9 while the insertion tube 7 is being pulled up.
It i9 obvious to a person skilled in the art that different embodiments of the invention may vary within the scope of the claims stated below. This concerns, above all, the construction of the cross-cutting means within the in~ertion tube 7 and its mode of operation. This means may operate mechanically, hydraulically,.pneumatically o- electrically.
Claims (6)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. Improvement in a procedure for creating a vertical drain by pushing into the ground an insertion tube carrying within itself a so-called prefabricated drain, by pulling out the insertion tube and cutting off the prefabricated drain, wherein the improvement comprises that the prefabricated drain is cut off with a cross-cutting means located within the insertion tube at such height, or in such a stratum as for instance a sand course, which accepts the water conveyed by the prefabricated drain.
2. Procedure according to claim 1, characterized in that the cross-cutting means is disposed close to the lower end of the insertion tube and that before cutting off the prefabricated drain the insertion tube is raised to desired height.
3. Apparatus for producing a vertical drain including an insertion tube adapted to receive a prefabricated drain, wherein the insertion tube has located therein a cutting blade movable in a direction transversal to the tube, and a counterblade located opposite thereto, and between which blades the prefabricated drain is adapted to be disposed.
4. Apparatus according to claim 3, characterized in that it comprises a cylinder transversal to the insertion tube and on the bottom of which the cutting blade is located;
that the cylinder is guided on a stationary piston affixed to the wall of the insertion tube; and that the cylinder has been connected to a pressurized fluid conduit entering the insertion tube through its top end.
that the cylinder is guided on a stationary piston affixed to the wall of the insertion tube; and that the cylinder has been connected to a pressurized fluid conduit entering the insertion tube through its top end.
5. Apparatus according to claim 4, characterized in that against the bottom of the cylinder acts a spring which returns the cutting blade to its initial position when the pressure has been voided from the cylinder.
6. Apparatus according to claim 3, characterized in that the cutting blade has been journalled by its ends in two opposed walls of the insertion tube and that with a view to rotating the cutting blade it carries on its end a sprocket wheel cooperating with a chain entering the insertion tube through its top end.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000379519A CA1153213A (en) | 1981-06-11 | 1981-06-11 | Procedure and means for creating a vertical drain |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000379519A CA1153213A (en) | 1981-06-11 | 1981-06-11 | Procedure and means for creating a vertical drain |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1153213A true CA1153213A (en) | 1983-09-06 |
Family
ID=4120208
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000379519A Expired CA1153213A (en) | 1981-06-11 | 1981-06-11 | Procedure and means for creating a vertical drain |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1153213A (en) |
-
1981
- 1981-06-11 CA CA000379519A patent/CA1153213A/en not_active Expired
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |