Hydraulic and earth engineering – Drainage or irrigation – Porous or apertured pipe – flume – or tileway
Reexamination Certificate
1999-02-25
2001-07-03
Lillis, Eileen D. (Department: 3672)
Hydraulic and earth engineering
Drainage or irrigation
Porous or apertured pipe, flume, or tileway
C405S036000
Reexamination Certificate
active
06254308
ABSTRACT:
The invention relates to an assembly for partially drying a zone of a substantially non permeable (or weakly permeous) ground containing a liquid. The invention is also directed to a method for drying such a zone.
BACKGROUND OF THE INVENTION
An equipment for drying a zone of ground weakly permeous to liquid, (especially water), is already known.
Such an equipment comprises:
a substantially air-tight membrane, covering the zone of ground to be dried and comprising a peripheral sealing means for allowing a partial vacuum to be obtained under the membrane,
an embankment permeous to water and disposed under the membrane, over the zone of ground to be dried,
first drain tubes disposed substantially vertically in the zone of ground and in fluid communication with the permeable embankment,
second drain tubes connected to a suction pump, those second drain tubes being laid substantially flat in the embankment and in fluid communication with the liquid collected in the first drain tubes, under the membrane.
Such an assembly including an air depressed membrane is already known, especially for reinforcing weak grounds impregnated with water and having a low permeability to water.
Such grounds are improper to receive buildings thereon.
For reinforcing such grounds and improving their mechanical strength, a partial vacuum is created under the membrane.
The permeable material of the embankment is typically sand. The sand is disposed on the zone of ground to be reinforced (i.e. a layer of weak clay).
SUMMARY OF THE INVENTION
An object of the invention is to propose a solution in connection with the following problems, (it is to be noted that in the following description, the liquid to be expelled from the ground is water, even if various other liquids could be concerned).
The problems to be solved include what follows:
effectiveness of the fluid suction, whatever the fluid may be (water, air . . . ),
speed of the ground compacting effect,
optimizing the arrangement of the various tubes, drain tubes, suction means, for improving the yield,
optimizing the height of the embankment for combining an efficient depression of air under the membrane and a height of embankment less than a critical height possibly involving a mechanical shearing of the embankment.
So, according to the invention, the second drain tubes comprise a series of fluid input holes opened within the embankment for communicating with the fluid contained in said embankment, in order to evacuate the liquid collected from the ground and obtain the required depression under the membrane.
Thus, the suction of air will be obtained from a larger area than in the prior art, within the embankment, the liquid to be expelled (and air to be exhausted) being taken from the embankment which will be partly filled with water (especially in its lower portion).
According to two other features of the invention:
the second drain tubes comprise a series of drain tubes, and the distance between two such successive drain tubes of the series is about 5 to 25 times larger than the vertical distance (height) between the level of the series of second drain tubes and a maximum level of the liquid within the embankment,
and the first drain tubes are separated from the second drain tubes, the liquid collected in the first drain tubes passing in the embankment before entering into the second drain tubes.
Thus, the distribution of the drain tubes will be optimized as in the ground as in the embankment, while improving the yield and thus, the speed of the ground compacting effect.
According to a preferred complementary feature of the invention:
the equipment further comprises complementary air suction tubes, for expelling air contained within the embankment and creating therein the air depression (in addition to, or instead of, the second drain tubes, the later being then only reserved for sucking up the water),
under the membrane, at least some of those air suction tubes are connected to third drain tubes which are laid flat in the embankment and which comprise a series of fluid input holes for an input of fluid therein,
the third drain tubes are disposed at a level above the level of the second drain tubes, in a zone of the embankment which is unsaturated with liquid, and those third drain tubes are connected to an air suction means.
For further improving the yield of the equipment, an other advice is as follows:
one of the third drain tubes is advantageously disposed substantially straight above one of the second drain tubes,
and at least locally in the embankment, the third drain tubes are disposed every other time over the second drain tubes.
In connection with the method for drying a ground, as taught by the invention, it is recommended to proceed as follows:
disposing the first drain tubes in the zone of ground to be dried, for collecting at least the portion of the liquid to be expelled for drying the zone,
disposing the second drain tubes in fluid communication with the liquid collected through the first drain tubes, while laying said second drain tubes flat over said zone of ground, within a draining embankment erected over the zone of ground to be dried and in fluid communication with the first drain tubes,
covering the embankment (and thus the zone of ground to be dried) with an air-tight membrane,
passing the second drain tubes through the membrane, while obtaining a sealing of said membrane, in such a way that a depression of air can be created thereunder, and
sucking gaseous and liquid fluids contained in the embankment, through fluid input holes provided in the second drain tubes, for creating said depression under the membrane while expelling the liquid from the ground.
If the embankment is provided with the abovementioned third drain tubes, it will be possible to substantially dissociate the suction of water (essentially through the second drain tubes) from the suction of air (essentially through the third drain tubes).
Further, the invention is as disclosed in the appended claims.
REFERENCES:
patent: 4020902 (1977-05-01), Valdespino
patent: 4293237 (1981-10-01), Robey et al.
patent: 4704047 (1987-11-01), Oldfelt et al.
patent: 4752402 (1988-06-01), Gray
patent: 4878781 (1989-11-01), Gregory et al.
patent: 5228804 (1993-07-01), Balch
patent: 5558463 (1996-09-01), Geisel
patent: 0329500 (1989-01-01), None
patent: 2663373 (1990-06-01), None
Lagman Frederick L.
Lillis Eileen D.
Menard Soltraitement
Rothwell, Figg, Erns & Manbeck, p.c.
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