NL8002772A - PRE-MANUFACTURED DRAIN FOR VERTICAL DRAINING. - Google Patents

Description

V.

P&C

W 5702-1 Ned.

Prefabricated drain for vertical removal.

The invention relates to a prefabricated discharge for vertical discharge, provided with an inner core and a surrounding outer filter layer.

In many countries there are large areas with fine deposits. 5 grained soft soil, such as clay. Due to the lack of better soil, roads, railways, airports and buildings often have to be constructed on such soft soil deposits. The construction work involves loading the soil and if no special measures are taken, landslides or subsidence can eventually occur, which will cause damage to the construction. Ground disturbances can also occur as a result of the fact that the carrying capacity of the soil is too low in its natural conditions.

By facilitating dewatering of the soil by means of vertical drains or drainage pipes, the long-term subsidence process, called consolidation, can be accelerated, so that settling will no longer take place after construction has been completed.

At the same time, as a result of the consolidation, the carrying capacity of the land will have improved. Often the acceleration of the dewatering is obtained by means of vertical drains or drainage pipes. Then sand drains or prefabricated drainage pipes are installed vertically in the ground to the desired depth. The soil is then loaded so that the water is squeezed or pressed from the clay to the drains and via it up to the soil surface and / or down to a strongly water-permeable substrate.

The aforementioned discharges of sand, as well as the previously known prefabricated drainage pipes, have certain drawbacks.

For example, the drains of sand are quite complicated to install. They are therefore quite expensive. They often have a diameter of about 150-500 mm for practical reasons. As a result, disturbances of the bottom during installation of the drains or drainage pipes can become considerable. The risk of constricting or strapping the drainage pipes of sand as a result of soil displacement in connection with the installation or during the consolidation process is also significant.

Prefabricated drainage pipes consist of an 800 2 7 72 "r - 2 - inner band-shaped plastic core with longitudinal channels.

The core is covered with a filtering, water-permeable layer of paper or a non-woven product, for example. Over the past few years, such drains have become more widely used, resulting in a declining market share for sand drains at least in certain areas. The growing demand for prefabricated drainage pipes may depend on their ease of installation and handling than sand drainage pipes. Usually, a prefabricated drainage pipe also has a diameter of only about 100x4 mm, which gives fairly small disturbances of the bottom.

In addition, the prefabricated drains usually have a significantly higher relative flow capacity than sand drains.

However, especially in the case of large drain lengths, the flow capacity of prefabricated drain pipes is also unsatisfactory.

This depends on the fact that if the drain pipes are long, they have such a high resistance to the source that their efficiency will be reduced. The channels between the core and the filter, which determine the ability of the drain pipe to drain water, are then too small in relation to the amount of water that is pressed into the drain pipe. Therefore, there is a great need for a prefabricated drain pipe with a higher flow capacity than that of the hitherto known prefabricated drain pipes.

In accordance with the present invention, a prefabricated drain pipe for vertical drainage is provided that fully meets this need. The drain pipe has an inner core and a surrounding outer filter layer. It contains a core in the form of a spiral or rings arranged parallel to each other and coupled together.

By means of this core, a large open channel with such a small source resistance is obtained, that it does not adversely affect the ability of the drain pipe to drain water.

Suitably, the coil is provided with spacers, etc., on the different coils to create a certain minimum distance between the coil when the coil is compressed. Thereby 800 2 7 72 - 3 - s

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water can enter the drainage pipe unhindered from the surrounding soil layers even when the coil is compressed. Thus, the radial flow of water in the drain pipe is determined by the permeability of the filter layer of the drain pipe.

Advantageously, the different passages of the spiral are connected to one another by one or more axially arranged wires or strips. These longitudinal wires or strips can be arranged either on the inside or on the outside of the spiral. The wires or strips are arranged in such a way that they prevent the spiral from extending so far that the filter is depressed by the surrounding pressure and so deep between the coils of the spiral that it is pulled apart.

During installation, the drain pipe will be stretched to its maximum length. Therefore, when the soil settles, the drain pipe 15 can be easily compressed and thus follow the soil displacement.

In this way the drainage pipe is prevented from curling, which can take place under certain circumstances with the band-shaped prefabricated drainage pipes. Naturally, the drainage capacity of a drainage pipe can be more or less lost if the drainage pipe curls in such a manner.

As a result, the drain pipe of the invention has acquired unique properties in its ability to resist deformation due to the displacement of soil. This ensures a maintained drainage capacity even under difficult conditions.

Due to the large flow capacity of the drainage pipe, its diameter can be made much smaller than is usual. As mentioned above, this reduces an unfavorable disturbance of the soil due to the installation of the drainage pipe. Such perturbations may include a decrease in strength, a decrease in permeability and a decrease in the consolidation coefficient.

For example, the drainage pipe can have a diameter of 20-50 mm. Preferably, the core of the drain pipe is made of a suitable plastic material, such as polyethylene. Various other plastic materials 35 can also be used. Also materials other than plastics 800 27 72 r - 4 - can be used on the condition that they give a strong, elastic and cheap product.

The filtering layer of the drainage pipe can for instance consist of paper, non-woven material, a micro-porous plastic or a perforated plastic.

The invention will be explained in more detail below with reference to the figure of the accompanying drawing.

Fig. 1 schematically shows a cross-section of a part of a first embodiment of a drain pipe according to the invention, wherein the spiral core 1 of the drain pipe extends maximally;

Fig. 2 shows a schematic cross section of the same piece of the drainage pipe according to FIG. 1.

However, core 1 is now compressed.

Thus, a first embodiment of the drain pipe 15 according to the invention comprises a spiral core 1, preferably made of plastic. The different passages of the spiral can be provided with spacer heads etc. 2 to create a certain minimum distance between the spiral passages when the spiral is compressed: As a result, the spiral cannot be compressed so far that it becomes difficult for the water to enter core 1.

The different passages of the spiral 1 are advantageously connected to one another by means of one or more axially arranged wires or strips 3. These can be arranged on the inside or on the outside of the spiral passages. The wires or strips 3 are intended to prevent the spiral 1 from extending so far that a filter layer 4 of paper etc. surrounding the spiral can be pressed between the spiral passes. The wires or strips 3 can be made from the same material as the core 1 or from a different material.

The distance between the different helices when the core 1 extends to the maximum can vary. However, it may be convenient for the distance to be about half the width to equal to the width of the coils.

When the core 1 is compressed, there should be a visible slot between the coils, which is clearly shown in Figure 2.

The present invention is not limited to the exemplary embodiment shown, as it can be modified in various ways within the scope of the present invention.

9002772

Claims (5)

1. Prefabricated drain pipe for vertical drainage comprising an inner core and a surrounding outer filter layer, which contains a core in the form of a spiral or rings arranged in parallel and coupled to each other. Drain pipe according to claim 1, characterized by a spiral core, for instance provided with spacer heads on the different spiral ducts in order to establish a certain minimum distance between the helical ducts when the helical compression is achieved. Drain pipe according to claim 1 or 2, characterized in that the spiral ducts are connected to each other by one or more axially arranged wires or strips, which are intended to prevent an unacceptable extension of the spiral. Drainage pipe according to any one of claims 1-3, characterized in that the spiral is made of a suitable plastic material, for example polyethylene. Drain pipe according to any one of the preceding claims, characterized in that the filtering layer consists, for example, of paper, non-woven material, a microporous plastic or a perforated plastic. 3002772