FR2813327A1 - DEVICE FOR DRAINING A FLOOR IN DEPTH - Google Patents

Abstract

The deep drain for soil has a drain with a chamber (3) having a lower face closed by a valve which is normally closed but opens when their is a vacuum in the chamber. The top of the drain has a closure (16) with three passages to receive a drain water level sensor (5). A compressed air feed pipe (6) is connected to an air reservoir (12) and through the upper level of the chamber. A drainage pipe (7) is connected to the lower section of the chamber.

Description

DEVICE FOR DRAINING A FLOOR IN DEPTH

  The present invention relates to a device for draining a deep soil by means of at least one drain, said drain comprising a chamber closed in its lower part by a valve arranged to be open when the chamber is in depression relative to the outside. and close when the chamber is overpressure, the chamber comprising a water or liquid level detector to be evacuated through the drain within said chamber, a compressed air inlet pipe connected to a reserve of compressed air and a hose for discharging water discharged from said chamber by air

  compressed and ending in the lower zone of the chamber.

  A device of this kind can be particularly suitable for draining soil following a deep landslide, but also for folding down the groundwater, for example, during

  carrying out large excavations, for moderately permeable soils.

  During a landslide whose shear surface is located at a significant depth, that is to say greater than ten meters, the stabilization techniques are very limited and it is often necessary to be content to follow

  deformation without being able to stabilize it.

  The mechanical stabilization solutions are much too heavy given the

huge masses to stabilize.

  Drainage solutions seem more attractive. Conventional vertical well techniques are frequently considered with conventional submersible pumps. However, the reuse of these pumps leads to management, maintenance and sustainability difficulties because the flow rates to be extracted per well are very variable and often low: 10 to 500 / h is the most common range of flow rates, except in rare cases for which punctually high flows can then be managed correctly

by submerged pumps.

  One can also use so-called "siphon" drains for which the water is discharged by a traditional siphoning. However, the depth to which water can be drained is limited by the maximum drop between the high point of the siphon and its outlet. This solution requires an outlet in sufficient elevation relative to the head of the siphon and its yield is reduced when the water is loaded with materials

  suspension, which is usually the case during a landslide.

  Also known in German patent DE-B-1 242 516 a device that described in the preamble. However, in this device, the outside of the chamber is constantly put under vacuum. This means that means must be provided on the drainage site for the creation of such a depression, which is particularly difficult to install on a borehole. On the other hand, the device alternately uses compressed air or a vacuum in the chamber, to connect the filling and evacuation phases of the water without interruption. There can then be an unnecessary consumption of air if there is no water to pump in the ground. More particularly when the flow to be extracted is discontinuous, this can also lead to a malfunction of the drain if the water does not rise for a certain time as far as the area

superior of the room.

  The present invention aims to overcome these drawbacks by proposing a device which makes it possible to drain a soil at great depth, which can operate at almost zero and / or discontinuous flows while requiring only drilling of small diameters, and which makes it possible to carry out savings in terms of compressed air consumption. To this end, the invention relates to a device of the type indicated in the preamble, characterized in that the chamber is closed at its upper part by a partition disposed deep in the drain, said partition comprising three passages for receiving the level detector, the exhaust pipe and the compressed air inlet pipe, and in that said compressed air inlet pipe ends up in the area

superior of the room.

  In a particularly advantageous manner, the level detector is constituted by an electric cable three conductors terminated by a contact and ending at different levels, respectively a first contact in the vicinity of the lower part of the chamber, a second contact slightly at- above the water evacuation tube then a third contact near the end of the tube

compressed air inlet.

  Said level detector is connected to an electrically powered solenoid valve control and itself connected to a three-way solenoid valve arranged to inject compressed air when the water level in the chamber reaches the third contact in the vicinity of the end of the compressed air supply tube and to stop the injection of compressed air when the water level drops below the second

contact.

  The solenoid valve can be connected to a reserve of compressed air supplied by a compressor.

  Advantageously, the water evacuation pipe comprises at least one check valve.

  back from the side of its end leading to the chamber.

  The water drain hose can be directed into a drop zone less than

  its outlet level from the drain to form a siphon rod.

  The device may include a series of drains as defined above, each drain having its own solenoid valve control and its own solenoid valve, the set of solenoid valves being supplied by a single reserve of compressed air which can be supplied by a compressor.

  The present invention and its advantages will appear better in the following description

  of an exemplary embodiment, with reference to the accompanying drawing in which the single figure schematically represents a section of the device according to the invention installed in

within a borehole.

  The drainage device 20 according to the invention comprises a drain 1 positioned at the level of a borehole. This drain could of course be launched, that is to say driven by injecting water at the base of the drain or implemented for any other known process. The

  drain 1 is placed vertically but can also be tilted.

  Perpendicular to the drain 1 is dug a pipe 15 into which opens

  the drain 1, and comprising inspection manholes 2 allowing access to the drain 1.

  It is of course possible to provide that the drain 1 opens directly at ground level. The drain 1 comprises on the side of its lower end a chamber 3 constituting a closed volume and closed in its lower part 17 by a valve 4 and in its upper part by a partition 16. The chamber 3 is positioned deep inside the drain 1 so that its lower part 17 is close to the lower end of the drain I in contact with water and that the partition 16 is itself disposed

  deep and sufficiently distant from the ground depending on the depth of the borehole.

  The valve 4 is arranged to be open to allow the liquid to be pumped into the chamber 3 when the chamber 3 is under vacuum relative to the outside and to close when the chamber 3 is over-pressurized. Any other system ensuring the same

functions can be used.

  In this variant, the chamber 3 is integrated into the drain. In this case, the wall of the drain 1 on the height of the chamber 3 is full and not screened to form a closed volume. In another variant not shown, the chamber can be separated from the drain

  and carried by a support, the drain can then have a screened portion.

  The partition 16 of the chamber 3 has three passages for receiving a level detector of the liquid to be discharged 5, a pipe 6 for the arrival of compressed air and a pipe 7

  evacuation of the pumped liquid out of the chamber.

  The level detector of the liquid to be evacuated consists of an electric cable 5.

  comprising three conductive wires, each wire being stopped at different depths and the end of which is stripped and terminated by contact. Thus, a wire is stopped in the vicinity of the lower part of the chamber 3 defining a first contact A. Another wire is stopped at a slightly higher level (about 10 cm) at the end of the pipe 7 defining a contact B and the last wire is stopped, in the upper part of the chamber 3 defining a third contact C. Thus, the contacts A, B, C are intended to detect the level of liquid in the chamber 3 respectively at the bottom of the latter slightly above of the arrival of

  water evacuation pipe and at the compressed air inlet pipe.

  The cable 5 is connected to an electrically powered solenoid valve control 9 and

  activating a three-way solenoid valve 10.

  The chamber 3 also comprises a pipe 6 for the arrival of compressed air, the lower end of which terminates in the upper zone of the chamber 3 substantially at the level of the contact C. The pipe 6 for the arrival of compressed air passes through the pipe. 15 and its other end is connected to the three-way solenoid valve 10, itself connected, by means of a valve 11 to a reserve 12 of compressed air supplied by a compressor 13. The

  reserve 12 is regulated between a minimum pressure and a maximum pressure.

  The solenoid valve 10 is arranged to inject compressed air into the chamber 3 through the pipe 6 when the water level in said chamber 3 reaches contact C near the end of the air intake tube 6 compressed, to stop the injection of compressed air when the water level drops below the second contact B and to

  return chamber 3 to atmospheric pressure.

  The chamber 3 also comprises a pipe 7 for discharging the water from the chamber 3, ending in the lower zone of the chamber 3, at a level slightly below the contact B. The pipe 7 for discharging comprises at least one valve check valve 8 chosen for

  support the weight of the evacuated water column.

  The evacuation pipe 7 passes through the protective pipe 15 and goes towards an outlet 14 located at an indifferent dimension and distance. It may however be advantageous to use the pipe 7 as a siphon rod if the difference in level of the outlet 14 allows it. For this, it will be driven into a lower elevation area compared to the high point of the siphon. Its end can then be treated either by raising it upwards, or by immersing it in a tank filled with water,

  the assembly then making it possible to work according to a siphoning principle.

  The device according to the invention constitutes an electropneumatic drain which operates in the following manner: when the water column within the borehole reaches a certain height, the chamber 3 then becomes in depression with respect to the pressure exerted by the water. Therefore, the valve 4 opens, the drilling fluid can then penetrate

  in chamber 3 by the hydrostatic pressure of the water column alone.

  At the same time, the chamber 3 is brought to atmospheric pressure by means of the pipe 6 and of the solenoid valve 10, the free air path of which is open. The passage of the fluid in front of the contact B opens the solenoid valve circuit 10. When the chamber 3 is full, the contact C opens the solenoid valve 10 so as to inject compressed air through the pipe 6. The chamber 3 becomes then in overpressure by

  outside and the valve 4 closes.

  The compressed air discharges the liquid out of the chamber 3 via the evacuation pipe 7 leading to the emptying of the said chamber 3, until the fluid passes again in front of the contact B, thus inducing the closing of the solenoid valve 10 and the

  return of chamber 3 to atmospheric pressure.

  The contact between C and A therefore opens the solenoid valve 10. On the other hand, the absence of

  contact between B and A closes said solenoid valve, if the latter is open.

  The water contained in the evacuation pipe 7 cannot go back down into the chamber

  3 due to the non-return valves 8.

  If the pipe 7 is used as a siphon rod, said pipe 7 is then primed, the volume evacuated from the chamber 3 being calibrated to be greater than the volume necessary for the pipe 7 to prime. The siphon then flows until it can be defused. The operation can thus be repeated periodically a large number of times

  to end up draining the borehole.

  The electropneumatic drain according to the invention makes it possible to be able to pump at great depth, by acting on the pressure of the compressed air, almost zero flow rates up to flow rates of less than 5 m3 / h; while requiring only boreholes of diameters

  low, which is particularly advantageous for very deep drilling.

  On the other hand, according to the invention, the injection of compressed air is done only when the chamber 3 is full. When the drain, on the height of the discharge, is empty, it can remain empty, without the need for compressed air. This allows a great saving of compressed air. Finally, putting the upper zone of the chamber 3 at atmospheric pressure after the liquid has been discharged from the chamber allows a new return of liquid into the chamber 3 by the valve 4 solely by the weight of the water in the outside the drain. This avoids the use of vacuum air, resulting in significant savings in

level of drilling equipment.

  The present invention is not limited to the embodiment described but extends to any modification and variant obvious to a person skilled in the art. In particular, it is possible to work with several drains in series, each drain having its own solenoid valve control and its own solenoid valve, the solenoid valve being supplied by

  a single reserve of compressed air supplied by a compressor.

Claims (7)

claims   1. Device (20) for draining a deep soil by means of at least one drain, said drain (1) comprising a chamber (3) closed in its lower part by a valve (4) arranged to be opened when the chamber (3) is in depression relative to the outside and is closed when the chamber (3) is in overpressure, the chamber (3) comprising a level detector (5) of the water or liquid to be evacuated through the drain within said chamber, a compressed air inlet pipe (6) connected to a reserve (12) of compressed air and a discharge pipe (7) for the water discharged from said chamber by the compressed air and leading into the lower zone of the chamber (3), characterized in that the chamber (3) is closed in its upper part by a partition (16) disposed deep in the drain, said partition (16) comprising three passages to receive the level detector (5), the exhaust pipe (7) and the compressed air supply pipe (6), and in that the edit compressed air inlet pipe (6)   ends in the upper zone of the chamber (3).   2. Device according to claim 1, characterized in that the level detector is constituted by an electric cable (5) three conductors terminated by a contact and ending at different levels, respectively a first contact (A) in the vicinity of the part bottom of the chamber, a second contact (B) slightly above the water evacuation tube (7) then a third contact (C) in the vicinity of   the end of the compressed air inlet tube (6).   3. Device according to claim 2, characterized in that said level detector   (5) is connected to an electrically powered solenoid valve control (9) and it   even connected to a three-way solenoid valve (10) arranged to inject compressed air when the water level in the chamber (3) reaches the third contact (C) near the end of the tube (6) supply of compressed air and to stop the injection of compressed air when the water level drops below the second contact (B).   4. Device according to claim 3, characterized in that the solenoid valve (10) is connected to a reserve of compressed air (12) supplied by a compressor (13). 5. Device according to claim 1, characterized in that the pipe (7) for discharging the water comprises at least one non-return valve (8) on the side of its end leading to the chamber (3).   6. Device according to claim 1, characterized in that the pipe (7) for discharging the water is directed into a drop zone lower than its outlet level from the   drain to form a siphon rod.   7. Device according to any one of the preceding claims, characterized in that   that it comprises a series of drains (1), each drain (1) having its own solenoid valve control (9) and its own solenoid valve (10), a set of solenoid valves (10)   being supplied by a single reserve of compressed air (1 2).