Classifications

• • E—FIXED CONSTRUCTIONS
  • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
  • E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
  • E02D19/00—Keeping dry foundation sites or other areas in the ground
  • E02D19/06—Restraining of underground water
  • E02D19/10—Restraining of underground water by lowering level of ground water
• • E—FIXED CONSTRUCTIONS
  • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
  • E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
  • E02D29/00—Independent underground or underwater structures; Retaining walls
  • E02D29/08—Siphons

Definitions

• the present invention relates to an automatic flushing device for regulating the operation of a drain-siphon comprising at least one vertical drain implanted in a ground to be stabilized, this drain being pumped by a main siphon whose upstream and downstream ends are immersed each in a liquid reservoir whose level is defined by a reference plane, said automatic flushing device comprising at least one vertical charge accumulator containing said reservoir into which the downstream end of said main siphon opens, this charge accumulator being pumped by a secondary siphon whose downstream end terminates in a main outlet, said secondary siphon being partially isolated inside a bell connected to said charge accumulator by a perforated lower part and the upstream end of said secondary siphon communicating with the atmosphere through a control duct.
• the deep drainage of the soil is carried out by discharging the liquid captured, mainly water, by means of one or more vertical drains arranged in the ground.
• This drainage can be carried out by various techniques such as pumping, gravity evacuation, siphoning.
• the invention applies to the latter technique namely to perform a pumping by a siphoning pipe or siphon set up in a drain located near a vertical drop geometrically allowing siphoning.
• This technique of drain-siphon DS is described in particular in the publication FR 2,593,203 of the same inventor, illustrated in FIG. 1 and can be applied to various fields such as pumping, tablecloth folding. deep excavations or compressible areas, embankment drainage, stabilization of landslides.
• a pumping siphon 3 provided with a ascending branch 30 housed inside each drain 1 and ending with an upstream end 31 permanently immersed in a reservoir 32 of liquid whose level is set on a reference plane PR, and a descending branch 33 inclined next the slope 20 of the land 2 and ending with a downstream end 34 whose outlet orifice 35 forms an outlet.
• the downstream end 34 can be immersed in a reservoir 36 of liquid whose level is set on the reference plane PR. It can also be in the open air and have in this case a curved end terminated by the outlet orifice 35 rising at said reference plane PR.
• the downward branch 33 of the siphon 3 is placed in the slope 20 of the ground 2 so that it is frost-free and out of the effects of the sun. It is also protected by tubes 37.
• Publication FR 2 719 085 by the same inventor proposes equipping the downstream end 34 of the siphon 3 with an automatic flushing device CA, as illustrated in FIG. 2, this device being arranged in a illustrated work of art. by a wall 12.
• the upstream end 31 of the main siphon 3 is immersed permanently in a reservoir 32 of liquid placed in the lower part of the drain 1, the upper level of said reservoir 32 being keyed on the reference plane PR.
• the reservoir 32 extends above said reference plane PR by a portion of perforated tube 38 allowing the penetration of water into said reservoir 32 and may constitute an additional filter.
• the reference plane PR is wedged below the high point PH of the main siphon 3 at a depth P given by the relation:
• pa is the lowest possible pressure at zero of the sea in meters of water
• x is the altitude of the place considered in meters
• f (9) is a function of the temperature ⁇ the highest that can reach the water in the siphon and corresponds to the vaporization pressure of the water at the water temperature in said siphon expressed in meters of water .
• the downstream end 34 of the main siphon 3 descends below said reference plane PR, is curved and ends with an outlet orifice 35 at said reference plane PR connected to a charge accumulator 4 in the form of a vertical tube , open in its upper part 40 and closed in its lower part 41 by a plug 42.
• This plug 42 is traversed by a tube forming a secondary siphon 5 provided with a descending branch 50 housed in the charge accumulator 4 and a U-shaped downstream end 51 always full of water in normal operation.
• the descending branch 50 of the secondary siphon 5 is enclosed in a bell 6, closed in its upper part 60 and perforated in its lower part 61 at its junction with the plug 42, the upper part of the perforations being at the level of the PR reference.
• the outlet orifice 52 of the secondary siphon 5 forms an outlet and ends at a level below the reference plane PR below the perforated lower portion 61 of the bell 6.
• a control pipe 7 communicates the downward leg 50 of the secondary siphon 5 with the atmosphere and is connected to it at a connection point 70 located in the lower part 41 of the charge accumulator 4 and more particularly in the plug 42.
• the free end 71 of the regulating conduit 7 has a stick shape which penetrates inside the upper part 40 of the charge accumulator 4, its outlet orifice 72 descending below the level of the inlet orifice 53 of the secondary siphon 5.
• the upstream level descends into the U-shaped downstream end 51 and the plane of contact between the pressurized air and the discharged water becomes vertical. Then this plane is smashed by the air that escapes through the outlet 52 and the secondary siphon 5 begins with the thrust of the water in the bell 6 allowing the main siphon 3 to activate through the decline fast water in the charge accumulator 4.
• the operation of the automatic flushing device C A as described above still has drawbacks.
• the degassing bubbles arrive through the main siphon 3 in the charge accumulator 4, they can be sucked inside the bell 6 in depression and can prematurely defuse the bell 6.
• the main siphon 3 has an inertia which is a function of its length and the amount of accumulated bubbles.
• the automatic flushing device CA can enter the defoaming phase too quickly, that is to say before all the degassing bubbles have been able to escape from the main siphon 3.
• the liquids from the drainage the water in majority, pose problems of deposition of calcite or clusters of iron bacteria, pipes and orifices can become clogged.
• the present invention aims to overcome these disadvantages by proposing to improve the current automatic flushing device by a simple device, economical, easy to implement, to prevent its defusing by the presence of degassing bubbles, prevent its fouling by deposition of calcite or iron oxides, and to guarantee a constant operation of the drain-siphon whatever. either the climatic conditions and / or the hydraulic load conditions in the borehole.
• the invention relates to a device of the type indicated in the preamble, characterized in that said secondary siphon comprises, in addition to said main outlet, at least one auxiliary outlet smaller than F main outlet, located at a level below that said main outlet and arranged to generate a slow flow regime, in that said charge accumulator comprises an enlarged zone integrating said reservoir into which the downstream end of said main siphon opens, said enlarged zone constituting a buffer reserve which is added reservoir and extends above said reference plane to a so-called buffer level, and in that said main outlet is located at the same level as said buffer level and said auxiliary outlet is located below said reference plane .
• the automatic flushing device allows the drain to be drained in two stages: a short operating cycle generating a rapid hydraulic load downstream of the main siphon, followed by a slow operating cycle allowing time for the bubbles to degassing to escape from said main siphon.
• the perforated lower end of said bell connected to said charge accumulator and the inlet of the downstream end of said main siphon in said enlarged zone are remote thereby avoiding degassing bubbles from being sucked by the bell in depression.
• the perforations of the lower end of said bell which is connected to the lower part of said charge accumulator are located just above said reference plane and delimit said liquid reserve.
• the downstream end of said secondary siphon advantageously has a U-shape which terminates in said main outlet and has a lateral branch terminated by said auxiliary outlet.
• the downstream end of said secondary siphon is coupled to a safety tank connected to said lateral branch, said safety tank having a lateral outlet opening forming said auxiliary outlet and being filled with liquid up to the level of said secondary outlet. said auxiliary outlet ensuring the filling of the U-shaped downstream end of said secondary siphon to a level called reserve level.
• Said safety tank may comprise permanent liquid supply means arranged to maintain said reserve level, these means may comprise a Mariotte vessel connected to said safety tank and coupled to a filling valve.
• said device may comprise means for treating the liquid pumped by said main siphon arranged to prevent fouling of said automatic flushing device by deposits, these means possibly comprising a liquid reservoir containing at least one treatment additive connected to said charge accumulator, which may advantageously consist of a Mariotte vessel connected to said enlarged zone and coupled to a filling valve.
• FIG. 1 is a schematic diagram of a drain-siphon of the prior art.
• FIG. 2 schematically represents an automatic flushing device associated with a drain-siphon of the prior art, and
• FIG. 3 schematically shows the improved automatic flushing device according to the invention.
• the automatic flushing device CA for regulating the operation of a drain-siphon DS constitutes an improvement of the known device according to FIG. 2 and the publication FR 2 719 085, which relates to a automatic flushing device CA connected to the downstream end 34 of the main siphon 3.
• the charge accumulator 4 which is formed of a vertical tube open in its upper part 40 and closed in its lower part 41 by a plug 42, has an enlarged zone 43 in its lower part 41. This enlarged zone 43 is extends above the plug 42 and beyond the reference plane PR and forms a buffer reserve up to a level called NT buffer level.
• the volume of this enlarged zone 43 is calculated to allow the total draining of the descending branch 33 of the main siphon 3 and the evacuation of the degassing bubbles before the defusing of the automatic flushing device CA.
• the outlet orifice 35 of the main siphon 3 enters said enlarged zone 43 through an inlet orifice 44 located just below the reference plane PR whereas the perforations of the lower part 61 of the bell 6 are located just above the reference plane PR.
• the bottom of the enlarged zone 43 contains a reserve of water 36 extending between the plug 42 and the reference plane PR in which opens the downstream end 34 of the main siphon 3 now the main siphon 3 still in water. Due to the presence of the enlarged zone 43, the outlet orifice 35 of the main siphon 3 is removed from the perforations of the lower part 61 of the bell 6 preventing the degassing bubbles from being sucked by the bell 6 under vacuum.
• the automatic flushing device CA is provided with two outlets 52, 54 of different diameters, located downstream of the secondary siphon 5: a main outlet 52 vertical corresponding to the outlet orifice of the secondary siphon 5 located above of the reference plane PR, and more precisely at the buffer level NT of the widened zone 43, and a lateral auxiliary outlet 54, of smaller diameter, situated on a bypass 55 of the secondary siphon 5 below the reference plane PR at a distance of NR reserve level.
• This reserve level NR defines the level of water contained in the lower part 51 in U secondary siphon 5 that seeks to maintain water.
• auxiliary outlet 54 The presence of these two outlets 52, 54 makes it possible to generate a drain of the drain 1 in two stages: a short operating cycle generating a rapid hydraulic load downstream of the main siphon 3 by the main outlet 52, followed by a cycle of slow operation allowing the degassing bubbles time to escape from the main siphon 3 through the auxiliary outlet 54.
• the diameter of the auxiliary outlet 54 is calibrated so that the flow it generates is slightly greater than the critical flow of the siphon main 3, when the hydraulic load on the bell 6 reaches the upper part of the perforations 61 causing the defusing.
• the device according to the invention comprises a safety tank 8 which is connected to the bypass 55 of the secondary siphon 5 and is provided with a lateral outlet opening forming the auxiliary outlet 54.
• the vertical position of the auxiliary outlet 54 defines the level of water contained in this safety tank 8, called the reserve level NR, which corresponds to the level of water contained in the lower portion 51 of the secondary siphon 5.
• the level of reserve NR is kept constant by means in the example shown, consist of a Mariotte vase 80 filled with water by a filling valve 81.
• Mariotte 80 comprises an upper portion 82 closed and a lower portion 83 closed which communicates with the reservoir of safety 8 by two ducts 84, 85 parallel stopping at NR reserve level, including a short conduit 84 opening at the base of the vase 80 and a long conduit 85 opening to the top of the vase 80 to put the top of the vase Mariotte 80 at atmospheric pressure when the NR reserve level tends to fall.
• the short duct 84 replenishes water by emptying part of the Mariotte 80 vessel until the reserve level NR rises and closes the short ducts 84 and 85.
• Mariotte 80 may be supplemented with water by the filling valve 81 connected to a water network and controlled manually or automatically according to a signal provided by a level detector or the like.
• the automatic flushing device CA also comprises means 9 for treating the water pumped into the soil through the drain 1 via the main siphon 3 in order to avoid the risk of clogging of the automatic flushing device CA by means of deposits of calcite, iron oxide bacteria or the like.
• the processing means 9 comprise a Mariotte vessel 90 filled with water containing at least one chemical treatment additive adapted as a function of the possible deposits by a filling valve 91.
• This treatment additive may be for example, sulfamic acid for calcite, hexametaphosphate of soda or oxalic acid for iron bacteria, or any other additive depending on the type of fouling to be feared.
• Mariotte vase 90 provides a constant flow, in particular a drop by drop, by acting on the atmospheric pressure and on the diameter of the short duct 94.
• the Mariotte 90 can be filled with liquid supplemented with chemical product (s) by the filling valve 91 manually or automatically.
• any other equivalent means may be suitable such as for example a simple exchange system obtained by osmosis. Possibilities of industrial application:
• the operation of the automatic flushing device CA according to the invention is now described.
• the water level in the charge accumulator 4 is lowered at the reference plane PR under the perforated lower part 61 of the bell 6 and the secondary siphon 5 keeps a water level in its lower part 51 U wedged on the reserve level NR defined by the auxiliary outlet 54 and the safety tank 8.
• the drain 1 is hydraulically recharged upstream, there is a rise in the water in the charge accumulator 4, the incoming water through the outlet 35 of the main siphon 3 in the enlarged zone 43.
• degassing bubbles entrained by the flow of water in the main siphon 3 open into the enlarged zone 43 they can be evacuated automatically by the upper part 40 open to the atmosphere of the charge accumulator 4. Unlike the known device, they are not sucked into the bell 6 by its perforated lower part 61, the latter being remote from the outlet orifice 35. The ascent water in the charge accumulator 4, simultaneously enters the bell 6 by its perforated lower part 61 and generates the increase in pressure of the air contained in the bell 6 and in the descending branch 50 of the secondary siphon 5.
• the secondary siphon 5 When under the air pressure, the secondary siphon 5 discharges the water contained in its U-shaped downstream portion 51 by the main outlet 52, the air pressure contained in the bell 6 and in the descending branch 50 relaxes starting the bell 6 and the secondary siphon 5 thus creating a rapid and brutal emptying of the charge accumulator 4 up to the buffer level NT corresponding to the first operating cycle. This creates a hydraulic load on the main siphon 3 1 loaded between the drain and hydraulically downstream of the main siphon 3 abruptly discharged by the flushing effect ⁇
• the purpose of the regulation duct 7 is to reinitiate the secondary siphon 5. In fact, it allows the water to be allowed to rise in the bell 6 when it goes up into the charge accumulator 4, since the air driven in front of it can escape through the control duct 7 by taking the descending branch 50 of the secondary siphon 5.
• the level of the water in the charge accumulator 4 reaches the outlet orifice 72 of the free end 71 of said duct 7, the air can no longer escape and increases in pressure at the top of the bell 6 and in the descending branch 50 of the secondary siphon 5.
• this flush is created in two stages:
• the . CA automatic flushing device may present itself in a dysfunctional situation if, at the moment when it is going to be put into action, there is a drop in the surrounding atmospheric pressure linked to climate change or the initiation of neighboring drilling disturbing the level of water in the borehole that was about to begin.
• the secondary siphon 5 can be started without the bell 6 starting. The next cycle can not be rebooted.
• the presence of the safety tank 8 avoids this risk and allows the U-shaped downstream portion 51 of the secondary siphon 5 to always be in water so that it is ready to be rebooted.
• the increase in atmospheric pressure can also be a source of dysfunction. It results in a decrease in the volume of air under pressure inside the bell 6 and the secondary siphon 5.
• the water level in the descending branch 50 of the secondary siphon 5 and in the bell 6 rises and can find at the inlet port 53 of said secondary siphon 5 and cause a drip situation. It must therefore be ensured that there is a sufficient difference in level between the level of the water in the bell 6, determined by the geometry of the regulation pipe 7 and the inlet orifice 53 of the secondary siphon 5.

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• 2012
  • 2012-06-28 FR FR1256162A patent/FR2992665B1/fr not_active Expired - Fee Related
• 2013
  • 2013-06-18 WO PCT/FR2013/000155 patent/WO2014001656A2/fr active Application Filing
  • 2013-06-18 EP EP13756522.2A patent/EP2867416B1/de active Active

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