This patent of Utility Model request deals with a new "DISPOSITION INTRODUCED IN A CIRCULAR VERTICAL DRAIN OR IN A REGULAR POLYGONAL VERTICAL DRAIN", particularly of a drain in the shape of a pipe with particular geometric characteristics to be used preferentially in embankments constructed on the soft lands, with the objective to promote the acceleration of the process of consolidation of the mentioned soft lands layers.

Technically, the drains are vertically spiked in the ground, since the surface until the layer subjacent to the soft land. The distribution of the vertical drains in plant is, typically, in triangles or quadrangles, with spacing between drains varying of 0,50 meters to more than 3 meters.

The vertical drain object of this patent request highlights, in general lines, for the shape adopted for the section of the drain, as well as for the configuration of the piece (called "foil"), used to fix said drain in the bottom of the cavity, when of the removal of the mandril used in this operation; such foil has changeable dimensions, adjusting to the diameters of drain and mandril.

APPLICATION FIELD

The main application of this invention is in the acceleration of consolidation of embankments constructed on grounds with soft lands.

GROUNDS OF THE ART

In the embankments, it is frequent the configuration of the soft land to a determined depth. Thus, when submitted to loads of embankments, the saturated soft lands, that is, whose vacuum are filled with water, they suffer consolidations (in lay terms, "sinkings"). Therefore, in case that the soft land layer is very thick, these consolidations can delay excessively to occur. For instance, in a typical case of the Brazilian coastal zone, the consolidations of a soft layer with thickness of 8 (eight) meters can take more than one decade to happen. This delay has scientific explanation with grounding in the physics, where two important aspects are related:

a) The consolidations can only happen by expulsion of the water that fills the vacuums of the soft land;

b) The soft lands have a very low permeability; thus, the water takes much time to cover the distance until the top (or the base) of the soft land layer. In technical terms, the necessary time so that the consolidations are completed is proportional to the square of the distance covered by the water. The analytical apparatus used to study this question is called "Thickening Theory", in Geotechnics (area of civil engineering that interests for grounds).

Thus, the vertical drains reduce the length that the water must cover to escape of the vacuum of the soft lands. Instead of having to cover all the vertical distance until the border of the soft layer, a water drop in a point any of the soft land have "to walk" (horizontally) only until the drain next. Once in the drain, the water goes up freely for it until the surface.

Consequently, in an embankment with soft land, using the system of vertical drains, the time so that the consolidations are completed diminishes extraordinarily. Thus, in the example above (soft layer with thickness of 8 meters), the use of vertical drains with spacing of 1 ,50 meters makes with that the time decreases of more than one decade to few months, what is expressively interesting.

STATE QF THE TECHNIQUE

The ribbon drains had been invented by Kjelman, in the Norway, in the end of years 40 of the last century. Before the prefabricated drains, sand drains were executed, that is: a steel pipe was spiked in the ground and filled of sand and, then the pipe was removed, leaving a sand column, through which the draining occurred. From the years 80, the prefabricated drains had been gaining space in function to be much more fast e cheap. Currently, the prefabricated drains are practically only used. Therefore, as it can be evidenced, there are prefabricated fibro-chemical drains of several national and foreign manufacturers; however all are of rectangular section, with preferential dimensions of 10 cm x 0,5 cm.

The prefabricated vertical drains of rectangular section have smaller spiking and manufacture costs, and the velocity of installation is bigger, what is intrinsically related to its geometric shape.

For better understanding of the question, it is necessary to emphasize that the efficiency of a system of vertical drains is calculated by the time that the consolidations lead to occur. The more efficient is the system, minor the time; thus, the efficiency depends on the size of the deformation ring that is formed around the drain because of the passage of the steel mandril used to spike it. The mandril necessary to spike the rectangular drains has great section, what raises the cost and increases the installation speed; finally, the deformed zone is equally bigger, provoking reduction in the efficiency of the drains.

Additionally, the drain-pipes of rectangular sections require very heavy machines for the process of spiking.

Related to the piece used to fix the drain in the bottom when of the removal of the mandril, here already called as "foil", in the drains found in the market, they are verified foils of several formats; however, none of them has the geometric conformation of the foil that integrates this patent request, whose characteristics and advantages will be clear.

It is known of the state of the technique, for instance, the patent application Pl 0500488-8, published in 26/09/2006, which deals with a "Drain for gas and leachate", in which a pipe (8) is simply connected into the organic material of leachate, for removal of gas, while a second tubing (12) receives, by gravity, the leachate, being still used a blanket of bidim (no woven geotextile) or similar for protection of the area. This type of drain does not have technical relation narrower with the said rectangular drain, once it is of course exempt of the problems with spiking through mandril, removed of the mandril and other problems related to the mentioned rectangular drains. OF THE NEW MODEL

The vertical drain object of this request of patent of Utility Model highlights, in relation to the pointed state of the technique, for presenting new shape or constructive disposition, involving a regular circular or polygonal section, opposing to the models of rectangular section of the other models existent in the market; and, in the model of this patent request, said foil can have any diameter.

Another innovative characteristic of this model consists of the piece (foil) used to fix the drain in the bottom of the cavity, when of the removal of the mandril, having changeable dimensions, adjusting to the different diameters of the drain and mandril.

Technically, the circular shape and the small diameter of the drain reduce the spiking and manufacture costs, increasing the velocity of installation. As final result, it is obtained a system of drains with efficiency equal or better to that one obtained by the usual systems, with smaller cost and time of installation.

As previously said, the regular circular or polygonal section of the drain presents small diameter, what reduces extraordinary the spiking and manufacture costs, increasing the velocity of installation. The final result is a system of drains with efficiency equal or better to that related to the drains of the usual systems, associated however to the smaller cost and time of installation.

It is an advantage of said model the fact of, because of the smaller section of the drain pipe, the mandril needed to spike said drain has section smaller than that needed to spike the currently existent drains. Thus, the deformed zone is also smaller, resulting in the increase of the efficiency of the drains.

Another advantage inherent to this model is that the pipe drains of small diameters can be spiked with machines much more light than the usual prefabricated drains, rectangular.

Still, the piece used to fix the drain in the bottom of the cavity, when of the removal of the mandril, that is, the foil, has the characteristic of changeable dimensions, allowing the adjustment to the diameters of the drain and mandril. In technical terms, it is important to point out that the efficiency of a system of vertical drains depends much more on the spacing between drains than the diameter of each drain; in function of this, the small diameter of the drains that motivates this request of patent, guarantees the full efficiency of the drain obtained through this patent.

DESCRIPTION OF THE DRAWINGS

To follow, the model will be explained on the basis of the attached drawings, which demonstrate the construction of the Circular Vertical Drain or Regular Polygonal Vertical Drain, wherein it sees:

Figure 1: it shows the straight section of the circular vertical drain inside the mandril (for diameters of the drain equal to 3 cm);

Figure 2: it shows the plant of the said foil, with detail of the diameter of the drain and external diameter of the mandril (circular or regular polygonal);

Figure 3: it shows the foil in perspective.

DETAILED DESCRIPTION

"DISPOSITION INTRODUCED IN A CIRCULAR VERTICAL DRAIN OR IN A REGULAR POLYGONAL VERTICAL DRAIN", object of this patent of Utility Model request, consists in a vertical drain (1) liable to have a circular or polygonal section, with any diameter, to be applied in the processes of acceleration of consolidation of embankments constructed on grounds with soft land. Technically, the drains (1) are spiked vertically in the ground, since the surface until the layer subjacent to the soft land. The vertical drains object of this patent request, as well as the other existent ones, must obey a distribution in plant, according to triangles or quadrates, preferentially with spacing between drains situated between 0,50 m and 3 m or little more.

Thus, when submitted to loads of embankments, the saturated soft lands (whose vacuum are filled with water) suffer consolidations, or "sinkings". As much thick the soft layer is, bigger the time of consolidation is, that it can take much time, in some cases, depending on the used ways, evaluated even though in years, or decades. Basically, as already said, two physical factors exist that influence in this delay, that is: first, the consolidations can only happen by expulsion of the water that fills the vacuum of the soft land; second, the soft land has very low permeability.

As the attached figures show, with reference specifically to figure 1 , a circular vertical drain (1) is visualized, confectioned preferentially in plastic material, which is lodged inside the mandril (2), whose external diameter (3) determined there is of

7 cm, and the internal diameter is of 4 cm. The drain (1) properly said preferentially presents a diameter of 3 cm, establishing with the mandril a dimensional relation that facilitates the spiking process, reducing time, cost, workmanship and using lighter machines for such a way, representing expressive advantages of the model.

This dimensional relation is preferentially kept independently of the regular circular or polygon section of the vertical drain (1). In accordance with figure 1 attached, the vertical drain (1) properly said is composed by a circular central core (4) (called star), obtained by extrusion of plastic material, preferentially with diameter around 10 mm, from which start multiples and regular striped arms (5) with length of

8 mm, being that, in the extremity of each striped arm (5), it is configured a circular station (6) of 2 mm of diameter is, while one of the striped arms incorporates an element with bigger area of contact (7) to receive a geotextile material (8), no woven, of contour of the vertical drain (1).

As described previously, the contour of the vertical drain (1) determined by the extremities of the striped arms (5) could be circular or, optionally, in the regular polygonal shape, receiving, of analogous way, the geotextile material (8); however, the preferential dimensional relations and the small diameter of the vertical drain (1) should be kept for being an element of great importance to the project.

Therefore, the circular (or regular polygonal) shape reduces the spiking and manufacture costs , increasing the velocity of installation; as said, in function of being vertical pipes-drains of small diameters, they can be spiked with machines much lighter in relation to the usual prefabricated drains.

The figure 1 attached shows, as already said, the vertical drain (1) inside the mandril (2), kept the respective diametrical relations, obviously being this a view from a section, what foresees a vertical drain (1) and mandril (2) prolonged by the extension usual in the market. In figure 2 attached, the plate (foil) (9) of circular configuration is shown, preferentially in steel sheet cut in stamping, having a changeable thickness as the necessities, preferentially between 0,2 mm and 4 mm, being the central area (10) of said foil (9) with diameter (11) compatible with the vertical drain (1). Foil (9) is introduced in the bottom of the mandril (2), in a concentrical shape and according to area of diameter (11) compatible with the vertical drain, being that related foil (9), as shown in figure 3, configures a plurality of regular radial lumps (12) directed to the interior of the mandril (2), in order to act against the vertical drain (1) properly said to keep inside the cavity when of the removal of the mandril (2).

The configuration of the foil (9), from regular radial lumps (12), generates the possibility of adjustment of said foil to the different diameters of drains (1) and mandrils (2), inside of values of tolerance not very extensive, obviously, because the dimensional values don't suffer big alterations, duly warned not to be efficient.

Therefore, a vertical drain (1), in accordance with this model, is highly simple, practical, allowing the attainment of cheaper drains, faster installation and keeping its efficiency, in function of the entire displayed one in this patent request.