NL2020551B1

NL2020551B1 - Method of forming a column in a ground

Info

Publication number: NL2020551B1
Application number: NL2020551A
Authority: NL
Inventors: Pieter Franklin Pekaar Leonard
Original assignee: Van Der Straaten Aannemingsmaatschappij B V
Priority date: 2018-03-08
Filing date: 2018-03-08
Publication date: 2019-09-13

Description

E02D 5/38 (2018.01) E02D 5/66 (2018.01) E02D 7/18 (2018.01) E02D 7/22 (2018.01)

Aanvraag ingeschreven:

september 2019 © Octrooihouder(s):

Van der Straaten Aannemingsmaatschappij B.V. te Hansweert.

(43) Aanvraag gepubliceerd:

47) Octrooi verleend:

september 2019 © Uitvinder(s):

Leonard Pieter Franklin Pekaarte Yerseke.

september 2019 © Gemachtigde:

ir. P.J. Hylarides c.s. te Den Haag.

54) Method of forming a column in a ground

5^ The present invention relates to a method of forming a column in a ground, comprising the steps of:

- inserting a casing at least partially into the ground;

- filling an interior of the casing at least partially with a curable material; and

- retracting the casing out of the ground while resonating said casing at a natural frequency thereof.

B1 2020551

Dit octrooi is verleend ongeacht het bijgevoegde resultaat van het onderzoek naar de stand van de techniek en schriftelijke opinie. Het octrooischrift komt overeen met de oorspronkelijk ingediende stukken.

Method of forming a column in a ground

The present invention relates to a method of forming a column in a ground.

Columns in a ground are often required to provide a support for a building or other structure. Especially when the ground is relatively soft, such columns are indispensable to prevent sagging of the supported building or structure over time.

Known methods of providing supporting columns comprises driving piles into the ground with heavy piling rigs that drive a pile into the ground using a heavy hammer. Besides causing loud noise, piling using a conventional hammer causes heavy vibrations in the ground and surroundings, and may even cause damage to nearby constructions. For example, cracks may be formed in walls of nearby buildings. Such prior art methods are energy demanding and not very sustainable.

Alternatives that are less obtrusive, comprise drilling a column into the ground with a special drill, and filling the drilled hole with a curable material while retracting said drill.

An object of the present invention is to provide a method of forming a column in a ground, that is improved relative to the prior art and wherein at least one of the above stated problems is obviated.

Said object is achieved with the method of forming a column in a ground according to the present invention, comprising the steps of:

- inserting a casing at least partially into the ground;

Resonating of the casing while retracting it out of the ground causes the curable material to smoothly flow out of the casing. Moreover, the resonating facilitates compacting of the curable material. Because the casing is retracted out of the ground, it may be re-used multiple times, contributing to a sustainable nature of the method according to the invention.

Although the specific control is not specifically described in this application, it is briefly mentioned that the natural frequency of a casing is dependent on many factors, such as the depth the casing is extending into and out of the ground, characteristics of the ground (layers) outside the casing and of the curable material inside the casing, as well as the ground water level and the wall thickness of the casing. As the casing is retracted and the length of said casing in the ground decreases while the length of the casing extending out of the ground increases, the natural frequency changes. Thus, the step of retracting the casing out of the ground while resonating said casing at a natural frequency thereof comprises adjusting of the natural frequency in correspondence to the actual situation.

In the following description preferred embodiments of the present invention are further elucidated with reference to the drawing, in which:

Figure 1 is a schematic overview of a crane with column forming equipment;

Figures 2 and 3 are perspective views of a drill head from above and below;

Figure 4 shows successive steps of forming a column in a ground with a method according to the invention.

The crane 1 in Figure 1 is standing on a ground 2 and is holding an upright 3 along which a drive 4 is moveable in downward and upward directions. The drive 4 engages a casing 5 at an upper end 6 thereof. The casing 5 is closed with a closure 8 at a lower end 7 thereof. This closure 8 may be embodied as a drill head 9.

The drill head 9 preferably comprises a receiving chamber 10 that is enclosed between an inner wall 11 and an outer wall 12 (Figures 2 and 3). The casing 5, which comprises a tubular cross sectional shape in the shown preferred embodiment, is dimensioned in correspondence with the receiving chamber 10.

A seal 13, preferably in the form of at least one o-ring 14, is preferably arranged between the lower end 7 of the casing 5 and the closure 8, i.e. the drill head 9. This seal 13 may prevent ground water from entering an interior 15 of the casing 5, where it may negatively influence the curable material 16 that is arranged in the interior 15 during the method of forming a column 17 in the ground 2. For example, the curing process may be delayed or the final strength that is obtained after curing may be reduced when (too much) water enters the interior 15 of the casing 5.

The curable material may be concrete, wherein the concrete is preferably of a quality suitable for underwater applications.

The method of forming a column 17 in the ground according to the present invention is now further explained using Figures 4a-4h, showing the steps of:

- inserting the casing 5 at least partially into the ground 2 (Figures 4c and 4d);

- filling the interior 15 of the casing 5 at least partially with the curable material 16 (Figure 4f); and

- refracting the casing 5 out of the ground 2 while resonating said casing 5 at a natural frequency thereof (Figure 4g). The drive 4 thus functions as a resonator, capable of resonating said casing 5 at a natural frequency thereof (Figure 4g). The resonator preferably adapts the natural frequency when the natural frequency changes due to the casing 5 being moved out of the ground 2.

The method preferably comprises the step of closing the casing 5 at the lower end 7 thereof with a closure 8 prior to the step of filling the interior 15 of the casing 5 at least partially with the curable material 16. If the casing 5 is closed at a lower end 7 thereof, two advantages are obtained. On the one hand, the casing 5 will not be filled with ground 2 that has to be removed (e.g. via drilling or suction) prior to the step of filing the interior 15 of the casing 5 at least partially with the curable material 16. On the other hand, the step of filling the interior 15 of the casing 5 at least partially with the curable material 16 may, in a not shown alternative method, even be executed prior to the step of inserting said casing 5 at least partially into the ground.

In the shown preferred embodiment, the closure 8 is a drill head 9, and the casing 5 and drill head 9 form an assembly 18, and wherein the step of inserting the casing at least partially into the ground comprises the step of drilling the assembly 18 of the casing 5 and the drill head 9 into the ground (Figure 4c). Alternatively, the casing 5 may be inserted at least partially into the ground by only resonating said casing 5 at a natural frequency thereof.

Due to the resonating of the casing 5, it lengthens and shortens at a high frequency of e.g. 140 Hz. The total elongation of the casing 5 may be in the order of 4-6 mm, i.e. 2-3 mm at each of the ends 6, 7, considering there is no elongation midway the length of the casing 5. If the lower end 7 moves at a frequency of e.g. 140 Hz and an amplitude of 2-3 mm, local accelerations in the order of 200 G are realistic. The resonating thereby causes the casing 5 to lower into the ground 2.

The step of drilling the assembly 18 of the casing 5 and the drill head 9 into the ground 2 preferably comprises rotating and simultaneously resonating said assembly 18 at a natural frequency of said assembly 18. As described above, the resonating of the casing 5 may cause a total elongation of the casing 5 in the order of 4-6 mm at 140 Hz. This is about 2-3 mm at each end, considering there is no elongation halfway along the length of the casing 5. Consequently, the shear resistance between the casing 5 and the surrounding ground 2 is highest halfway along the length of the casing 5, but gradually decreases in magnitude towards the ends. Consequently, a relative light rotator suffices to overcome the shear resistance that is already reduced as a result of the resonating action. The drive 4 may function both as a resonator and a rotator at once. Alternatively, a (not shown) further drive may be applied, wherein at least one of the drive 4 or the further drive is a resonator, and at least one of the other of the drive 4 or the further drive is a rotator. If the assembly 18 of the casing 5 and the drill head 9 is inserted into the ground 2 by rotating and simultaneously resonating at a natural frequency of said assembly 18, the wear of the casing 5 will be reduced to a minimum. As a result, the casing 5 may be re-used multiple times, resulting in a sustainable method of forming the column 17 in the ground 2.

It is mentioned here that the method as described in the previous paragraph describes at least resonating said assembly 18 at a natural frequency of said assembly 18 when the assembly 18 of the casing 5 and the drill head 9 is inserted into the ground 2, and at least resonating the casing 5 at a natural frequency of the casing 5 when the casing 5 is retracted out of the ground. Thus, when the casing 5 is inserted into the ground 2, the natural frequency of the assembly 18 is leading. However, when the casing 5 is retracted from the ground 2, the natural frequency of only the casing 5, also being influenced by the curable material 16 arranged therein, is leading.

Preferably, the casing 5 is also rotated during inserting into the ground 2 and during retraction out of the ground 2. The step of retracting the casing 5 out of the ground 2 while resonating said casing 5 at the natural frequency thereof, thus preferably also comprises simultaneously rotating said casing 5. The resonating of the casing 5 while retracting it out of the ground 2 causes the curable material 16 to smoothly flow out of the casing 5. Moreover, the resonating facilitates compacting of the curable material 16. If the casing 5 is simultaneously rotated and resonated, the casing 5 can be removed in a controlled way.

The step of filling the interior 15 of the casing 5 at least partially with the curable material 16 (Figure 4f) comprises the step of at least partially pumping said curable material 16 therein. Although pouring said curable material 16 is also possible, pumping is preferred to obtain an optimal fill.

The method preferably comprises the further step of arranging a reinforcement 19 in the curable material 16 (Figures 4d and 4e). Preferably, the reinforcement 19 is arranged in said interior 15 of said casing 5 before the step of filling said interior 5 (Figure 4f) at least partially with said curable material 16. In this order, the reinforcement 19 can be securely placed inside the interior space 15. In order to obtain an optimal filling of the interior space 15 with reinforcement 19, it may be advisable to apply a curable material 16 that easily passes the reinforcent 19, If concrete is used, a relatively small grain size may be chosen.

The method comprises the steps of disengaging the casing 5 from the closure 8 in the step of retracting the casing 5 out of the ground 2 (Figure 4g), and leaving the closure 8 in the ground 2 below the column of curable material 16 (Figures 4g and 4h). If the closure 8 is a drill head 9, it comprises the step of disengaging the casing 5 from the drill head 9 in the step of retracting the casing 5 out of the ground 2, and leaving the drill head 9 in the ground 2 below the column 17.

In step 4f, the interior 15 of the casing 5 is preferably filled till above the ground level (Figure 4f), e.g. till about 2 meters above ground level. The resonating of the casing 5 while retracting it out of the ground 2 causes the curable material 16 to smoothly flow out of the casing 5. The curable material 16 then fills the void left by the wall of the retracting casing 5. Consequently, the level of the curable material 16 lowers from above ground level (Figure 4f) to about at ground level (Figure 4h), indicated with ΔΕ in Figure 4.

Dependent on the dimensions of the casing 5, the method may comprise the additional step of introducing further curable material 16 into the interior 15 of the casing during the step of retracting the casing 5 out of the ground. For example, if a casing 5 has a length of 19 m and a diameter of 0.355 m, the casing 5 may extend at least about 2 meters above ground level in the step shown in Figure 4e, and the interior 15 is preferably completely filled with curable material in the step shown in Figure 4f. In order to provide a column 17 that has an upper end near ground level (as shown in Figure 4h), it may be required to introduce a further height of 8-10 m of 5 curable material 16 into the interior 15 in the step shown in Figure 4g.

The above described embodiment is intended only to illustrate the invention and not to limit in any way the scope of the invention. Accordingly, it should be understood that where features mentioned in the appended claims are followed by reference signs, such signs are included solely for the purpose of enhancing the intelligibility of the claims and are in no way limiting on the scope of the claims. The scope of the invention is defined solely by the following claims.

Claims

Conclusies

1. Werkwijze voor het vormen van een kolom in een grond, omvattende de stappen van:

- het ten minste gedeeltelijk in de grond aanbrengen van een bekisting;

- het ten minste gedeeltelijk vullen van een binnenste van de bekisting met een uithardbaar materiaal; en

- het uit de grond terugtrekken van de bekisting en het gelijktijdig resoneren van de bekisting op een eigenfrequentie daarvan.
2. Werkwijze volgens conclusie 1, waarbij de stap van het ten minste gedeeltelijk in de grond aanbrengen van de bekisting, de stap van het resoneren van de bekisting op een eigenfrequentie daarvan omvat.
3. Werkwijze volgens conclusie 1 of 2, omvattende de stap van het, voorafgaand aan de stap van het ten minste gedeeltelijk vullen van het binnenste van de bekisting met het uithardbaar materiaal, met een afsluiting afsluiten van de bekisting aan een onderste uiteinde daarvan.
4. Werkwijze volgens conclusie 3, waarbij de afsluiting een boorkop is, en de bekisting en de boorkop een samenstel vormen, en waarbij de stap van het ten minste gedeeltelijk in de grond aanbrengen van de bekisting, de stap van het in de grond boren van het samenstel van de bekisting en de boorkop omvat.
5. Werkwijze volgens conclusie 4, waarbij de stap van het in de grond boren van het samenstel van de bekisting en de boorkop, het roteren en gelijktijdig op een eigenfrequentie van het samenstel resoneren van het samenstel omvat.
6. Werkwijze volgens een willekeurige van de voorgaande conclusies, waarbij de stap van het uit de grond terugtrekken van de bekisting en het gelijktijdig resoneren van de bekisting op een eigenfrequentie daarvan, het gelijktijdig roteren van de bekisting omvat.
7. Werkwijze volgens een willekeurige van conclusies 3-6, omvattende de stap van het aanbrengen van een afdichting tussen de bekisting en de afsluiting.
8. Werkwijze volgens conclusie 7, waarbij de afdichting ten minste één o-ring omvat.
9. Werkwijze volgens een willekeurige van de voorgaande conclusies, waarbij de stap van het ten minste gedeeltelijk vullen van het binnenste van de bekisting met het uithardbaar materiaal, de stap van het ten minste gedeeltelijk daarin pompen van het uithardbaar materiaal omvat.
10. Werkwijze volgens een willekeurige van de voorgaande conclusies, verder omvattende de stap van het, tijdens de stap van het uit de grond terugtrekken van de bekisting, in het binnenste van de bekisting inbrengen van verder uithardbaar materiaal.
11. Werkwijze volgens een willekeurige van de voorgaande conclusies, waarbij het uithardbaar materiaal beton is.
12. Werkwijze volgens conclusie 11, waarbij het beton van een kwaliteit is, welke geschikt is om onder water toegepast te worden.
13. Werkwijze volgens een willekeurige van de voorgaande conclusies, verder omvattende de stap van het in het uithardbaar materiaal aanbrenger! van een wapening.
14. Werkwijze volgens conclusie 13, waarbij de wapening, voorafgaand aan de stap van het ten minste gedeeltelijk vullen van het binnenste van de bekisting met het uithardbaar materiaal, in het binnenste van de bekisting wordt aangebracht.
15. Werkwijze volgens een willekeurige van conclusies 3-14, omvattende de stappen van:

- het vrijmaken van de bekisting van de afsluiting tijdens de stap van het uit de grond terugtrekken van de bekisting; en

- het in de grond, onder de kolom van uithardbaar materiaal, achterlaten van de afsluiting.

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