US20240240427A1

US20240240427A1 - Diaphragm wall cutter and method for cutting a cutting trench in the ground

Info

Publication number: US20240240427A1
Application number: US18/559,308
Authority: US
Inventors: Ulli WIEDENMANN; Stefan Roth
Original assignee: Bauer Maschinen GmbH
Current assignee: Bauer Maschinen GmbH
Priority date: 2021-05-06
Filing date: 2022-04-27
Publication date: 2024-07-18

Abstract

The invention relates to a diaphragm wall cutter for cutting a cutting trench in the ground, comprising a cutting frame, at least one rotatably drivable cutting wheel which is mounted on an lower side of the cutting frame, a suction nozzle, which is arranged in the region of the at least one cutting wheel and is provided with at least one suction opening, and a suction pump which is configured for suctioning slurry from the cutting trench during cutting via the suction nozzle, the suction pump being connected to the suction nozzle via a suction line. According to the invention, it is provided that at least one filling port is provided for filling the suction pump and the suction line with a liquid when the suction line is shut-off, wherein the suction line and the suction pump are filled with liquid for starting the suction pump.

Description

The invention relates to a diaphragm wall cutter for cutting a cutting trench in the ground, comprising a cutting frame, at least one rotatably drivable cutting wheel which is mounted on an lower side of the cutting frame, a suction nozzle which is arranged in the region of the at least one cutting wheel and is provided with at least one suction opening, a suction pump, which is configured for suctioning slurry out of the cutting trench during cutting via the suction nozzle, wherein the suction pump is connected to the suction nozzle via a suction line according to the preamble of claim 1.
The invention further relates to a method for cutting a cutting trench in the ground with a diaphragm wall cutter, according to the preamble of claim 14.
Diaphragm wall cutters are used for the construction of so-called diaphragm walls or cut-off walls, which are required, for example, for securing or sealing excavation pits. By means of a diaphragm wall cutter, ground material is removed by rotatingly driven cutting wheels and suctioned in via a suction pump together with surrounding supporting slurry or flushing liquid in the cutting trench and discharged to above ground. The discharged slurry or flushing liquid can be depleted of removed ground material above ground in a treatment plant, and the slurry or flushing liquid can be returned into the trench. Such a diaphragm wall cutter and such a process are known, for example, from DE 41 41 629 A1 or EP 2 586 962 A1.
To remove the slurry or flushing liquid from the cutting trench, it is known from the generic EP 3 556 942 B1, for example, that by means of a suction pump on the cutting frame to suction-in slurry or flushing liquid together with the removed ground material via a suction nozzle arranged between two pairs of cutting wheels.
For secure and long-lasting mode of operation of the suction pump, it is imperative that the suction pump does not suction-in air and thus run dry or empty. This is a particular problem at the start of cutting when no trench or only a trench with a shallow depth is formed.
To avoid this problem, it is known to excavate a trench, the so-called pre-excavation, on the ground at the beginning of the cutting operation, for example with the aid of an excavator. This trench can also be used as a guide trench, i.e. to guide the cutting machine during excavation of the first trench section. The diaphragm wall cutter can then be inserted and positioned in the trench at the start of cutting, filling the initial trench with liquid. When the suction pump is started up, it is already in the trench filled with liquid, usually slurry. Depending on the size of the diaphragm wall cutter and the position of the suction pump on the frame of the diaphragm wall cutter, it may thus be necessary to create a guide trench with a depth of several meters before starting the cutting work.
Creating an trench with a depth of several meters requires additional construction machinery, such as an excavator, and results in a considerable effort of work and time. The deeper the trench has to be and the harder and rockier the in-situ ground is, the more of this effort is required.
The object underlying the invention is to specify a diaphragm wall cutter and a method with which a cutting trench in the ground can be created particularly efficiently.
The object is achieved, on the one hand, by a diaphragm wall cutter having the features of claim 1 and, on the other hand, by a method having the features of claim 14. Preferred embodiments of the invention are indicated in the respective dependent claims.
The diaphragm wall cutter according to the invention is characterized in that at least one filling port is provided for filling the suction pump and the suction line with a liquid, wherein the suction line and the suction pump are filled with liquid for starting the suction pump.
A basic idea of the invention is to avoid idle running of the suction pump at the beginning of the cutting process by filling the suction line, which extends between the at least one suction opening on the suction nozzle and the suction pump, with a liquid via a filling port on the diaphragm wall cutter. The liquid is preferably water, but in the context of the invention may also comprise a slurry, i. e. a liquid to which solids or solid components or a binder have been added. In particular, the liquid may correspond to the slurry to be aspirated from the cutting trench. By filling the suction line in this way, it is ensured that when cutting begins, the suction pump does not suction-in air but liquid directly. This ensures that the suction pump can suction-in liquid immediately at the start of cutting and thus start the flushing cycle in the trench to be created.
The diaphragm wall cutter according to the invention makes it possible to insert a diaphragm wall cutter into a relatively shallow guide trench with filled slurry, wherein only the at least one suction opening of the suction nozzle is immersed in the slurry. Thus, with the diaphragm wall cutter according to the invention, the effort for creating a guide trench can be considerably reduced, since only a relatively shallow guide trench or a basin filled with slurry is required around the cutting point.
According to a further development of the invention, it is preferred that a shut-off device is provided by means of which the suction line can be shut-off downwards to the cutting trench, and that the shut-off device has a locking element which is mounted to be adjustable between a shut-off position and a flow position. Shutting off and filling the suction line can in principle also be provided if the diaphragm wall cutter is already inserted at the start of cutting as far as the suction pump or even altogether into a previously created pre-excavation or guide trench which is filled with liquid. At the start of cutting, the shut-off device can then be detached so that slurry is suctioned in from the previously created guide trench via the suction line without air entering.
The shut-off device can be a unit on the diaphragm wall cutter, via which a locking element mounted thereon can be adjusted. The locking element can, in particular be an adjustment bolt or a blocking valve, which is arranged on the suction nozzle or a suction channel between the suction nozzle and the suction pump.
In principle, manual operation of the shut-off device can be provided. According to a further development of the invention, it is particularly expedient that the locking element is adjustable, in particular displaceable or pivotable, between the shut-off position and the flow position by means of an actuating drive. For this purpose, a hydraulic, pneumatic or electric actuating drive for adjusting a latch or an electrically operable blocking valve can be provided. In principle, several locking elements can also be provided. The actuating drive of the shut-off device can be actuated by an operator or automatically by a control unit when the cutter is started up.
In principle, the locking element can be arranged at any suitable position to ensure sufficient filling of the suction pump and the upstream suction line with slurry. A particular advantageous embodiment of the invention is that the locking element is arranged on the suction nozzle or on the suction line.
A particularly simply designed embodiment variant of the invention is that the shut-off device has at least one closing cover which can be loosened when the suction pump is started up. The closing cover can be placed manually on the at least one suction opening on the suction nozzle in a simple manner. When the suction pump starts up, the closing cover can then be suctioned off by the suction pressure alone and thus unblocking the suction opening.
It is particularly expedient that a closing cover is detachably attached to each suction opening of the suction nozzle. This design dispenses with the need for a complex control device. Thus, the area up to the suction nozzle can also be filled with liquid.
In principle, the at least one closing cover can be retained on the suction nozzle by a bracket, chain or rope, so that the closing cover can become detached from the suction nozzle but is captive. Before a new cutting process, the at least one closing cover can be returned again to the closure position.
A particularly simple embodiment of the invention is that the at least one closing cover is configured as a disposable element which can be detached by suction when the suction pump is started up. The closing cover can be recovered again when the slurry is recirculated in a processing plant with an appropriate screening or filtering device.
The closing cover can be formed from basically any suitable material, in particular a plastic, a rubber material or a metal. According to one embodiment variant of the invention, it is particularly advantageous that the closing cover is formed with a degradable material, in particular a biopolymer plastic. Also, a wood-based material may be used. In this way, the closing cover can remain in the slurry without having any adverse effect on the environment. Preferably, a ceramic material may also be provided. A ceramic lid can break during discharge and behave like rock material, i. e., there is no risk of clogging the suction line. In addition, ceramic material is environmentally compatible.
In principle, any opening to the suction pump, to the suction line or to the suction nozzle can be used as a filling port. A particularly advantageous embodiment of the invention is that the filling port is arranged on or above the suction pump. Simple filling can be performed from above. The filling port ensures that after the lower line portion up to the suction pump has been shut off, it can be filled with slurry. The filling port is arranged in such a way that air is largely completely displaced by the filled slurry via this port or a corresponding vent valve.
A filling port above the suction pump also ensures that the suction pump, as a whole is filled with liquid at the start of cutting and can thus reliably suction-in the flushing liquid or slurry.
In principle, a filler neck for manual filling can be provided at the filling port. According to a further development of the invention, it is particularly advantageous that the filling port is configured for detachable attachment of a hose line and preferably has a non-return valve. The filling port can preferably have a quick coupling system or a thread for attaching a hose line in a conventional hose size. A check valve at the filling port ensures that no slurry escapes at the filling port when the hose line is removed and during further operation of the diaphragm wall cutter.
Another preferred embodiment of the invention is that a filling pump is provided through which a defined quantity of liquid can be supplied for filling. The filling pump can be arranged on the diaphragm wall cutter itself. Alternatively, an external filling pump can be provided, which is also used, for example, for filling the cutting trench with supporting slurry.
It is also possible to use a diaphragm wall cutter without a shut-off device. Here, according to one embodiment variant of the invention, it is preferred that, with the suction line open at the bottom, liquid can be supplied into the suction pump and the suction line prior to start-up of the suction pump in such a quantity that before the suction pump is started, these are filled for starting the suction pump. This means that more liquid is supplied from above than can flow out of the suction line downwards. This can prevent undesirable idle running of the pump and air being suctioned-in.
In principle, the filling pump can be operated manually by a machine operator. According to a preferred embodiment of the diaphragm wall cutter according to the invention, it is advantageous that a control device is provided which is configured to stop filling when the suction pump is started. If the suction pump is started, the control device can automatically stop the filling pump immediately or with a certain predetermined time offset. This ensures efficient operation of the diaphragm wall cutter.
A further development of the invention is that the control device directly controls the filling pump and/or a valve device which is attached to the filling port. The control device can thus not only directly control a filling pump, but additionally or alternatively control a valve device, so that filling of the suction pump from above is set off at the beginning of the actual operation of the suction pump. By means of a valve device on the supply line to the suction pump, the filling process can be immediately and completely prevented by a corresponding shut-off.
When using the pump to create a slurry circuit for the supporting liquid, merely controlling the valve means to stop the filling process may also be sufficient, wherein then the pump can continue to run, in order to supply supporting liquid to the trench.
According to another further development of the invention, it is advantageous that a display device is provided which displays a filling state of the suction pump. For this purpose, one or more sensors can be provided on the suction pump and/or on a suction duct and/or on suction nozzle. These are connected to the display device of a control unit, preferably in the operator's cab of an associated carrier unit to the diaphragm wall cutter. Thus, at the start of cutting, it can be ensured that there is actually no or hardly any air in the area of the suction pump. In principle, the control unit can be configured in such a way that, if insufficient filling is detected, cutting and suction operations are blocked. The control unit can also control the course of further cutting in such a way that, in the case of an adjustable locking element, this is opened immediately when the suction pump starts up or shortly thereafter, so as to ensure continuous suction of liquid via the suction nozzle.
The invention further relates to a method for cutting a cutting trench in the ground with such a diaphragm wall cutter, wherein the method is characterized in that the suction pump and the suction line are filled with a liquid via the filling port before the suction pump is started.
In particular, the method can be performed by the above-described diaphragm wall cutter, wherein the advantages described above can be achieved.
A particularly preferred variant of the method according to the invention is that a guide trench is created, which is filled with slurry, and that the diaphragm wall cutter is inserted into the guide trench for cutting, wherein the cutting operation is started even before the suction pump is completely immersed in the slurry. In particular, the guide trench is formed with such a depth that at least the suction nozzle with the at least one suction opening is immersed in the slurry in the guide trench. When cutting begins and the suction pump starts up, any shut-off device provided is then opened, with an initial suction pressure already being generated by the suction pump at the time of opening, which prevents a backflow of slurry from the suction pump into the guide trench. Instead, the suction pressure of the suction pump at the time of opening is set in such a way that slurry is continuously suctioned from the guide trench by the suction pump via the suction nozzle. An inflow at the guide trench can be used to ensure that there is a sufficient inflow of slurry in the guide trench. The inflow can be connected to a slurry circuit, through which slurry suctioned in by the diaphragm wall cutter is fed back again in sufficient quantity after any necessary removal of milled ground material in a processing plant, if necessary, with added slurry, to fill the enlarging cutting trench.
According to a further variant of the method according to the invention, it is advantageous that before the start of cutting, the suction line downwards to the cutting trench is shut off by means of a shut-off device and that the shut-off device is opened when it is immersed in the slurry, wherein the suction line is filled with liquid. Both when using a diaphragm wall cutter with shut-off device and without shut-off device, it must be operated in such a way that the suction pump is filled with liquid, in particular slurry, when it is started up.
The shut-off device is to be opened at a suitable time depending on the process sequence, in order to ensure an uninterrupted suction flow of slurry through the suction pump. According to a further development of the invention, it is particularly useful for the shut-off device to be opened when it is immersed in the slurry. As soon as the shut-off device is immersed in the slurry, it is ensured that the area below the shut-off device is filled with slurry. After the line system above the shut-off device is filled with slurry via the filling port, the shut-off device can be opened at this point of time with a high level of operational safety to counteract the risk of a larger quantity of air being suctioned into the suction pump.
A separate filling pump, in particular, a self-priming pump or a vacuum pump, can also be arranged at the filling port. This allows the suction line to be filled via the suction openings when the shut-off device is open. When the suction pumps are in operation, the filling pump can be switched off.
A particularly efficient method variant results from the fact that the shut-off device is opened when the suction pump has reached a rotational speed required for suction or has built-up a negative pressure required for extraction.
A particularly expedient procedure implementation further results from the fact that, with the suction line open downward, liquid is fed into the suction pump and the suction line by means of a filling pump in a quantity such that the suction pump and the suction line are filled when the suction pump is started.

The invention is further described below with reference to a preferred exemplary embodiment, which is shown schematically in the drawings. The drawings show in:

FIG. 1 a schematic side view of a diaphragm wall cutter according to the invention;

FIG. 2 a schematic illustration at the beginning of creating a cutting trench according to a method according to the invention;

FIG. 3 a schematic side view of the diaphragm wall cutter of FIG. 2 at the time of creating the cutting trench according to the invention;

FIG. 4 a schematic side view of the diaphragm wall cutter of FIGS. 2 and 3 during further sinking of the cutting trench;

FIG. 5 an enlarged schematic cross-sectional view through a suction nozzle according to a further embodiment of a diaphragm wall cutter according to the invention; and

FIG. 6 a schematic connector assembly for operating a diaphragm wall cutter according to the invention.

According to FIG. 1 , a diaphragm wall cutter 20 according to the invention has a cutting frame 22, on the lower side of which rotatably mounted and driven lower cutting wheels 24 are arranged for removing ground material. The preferably box-shaped cutting frame 22 can be suspended from a carrier device, which is not shown, via a suspension cable or guided via a guide rod. For suctioning off cut-off ground material, the diaphragm wall cutter 20 is provided with a suction pump 30 on the cutting frame 22, which is arranged above the lower cutting wheels 24.
Via a suction line 28 and a suction nozzle 26, which is positioned centrally between the two pairs of cutting wheels 24, cut-off ground material can be suctioned in together with surrounding slurry 16 during cutting. The suction nozzle 26 is provided here with suction openings not shown in FIG. 1 . The slurry 16 can be a liquid, in particular water, preferably a cutting slurry provided with a binding agent, in which milled-off ground material accumulates during cutting.
With the diaphragm wall cutter 20 according to the invention, a shut-off device 40 with a plate-shaped locking element 42 can be arranged at the lower end of the suction line 28 towards the suction nozzle 26. In the illustration according to FIG. 1 , the locking element 42, which is in the form of a spool, is in an opening or flow position. The locking element 42 can be displaced by an actuating drive, which is not shown, into a shut-off position in which the locking element 42 shuts off the suction line 28 in a sealing manner downward toward the suction nozzle 26 and which is shown in FIG. 2 .
Via a schematically indicated filling port 50 on the suction pump 30, liquid can be introduced into the suction pump 30 and the suction line 28 when the suction line 28 is shut off, as clearly illustrated in FIG. 2 . In a simple manner, filling can be accomplished via a water line hose that is detachably connected to the filling port 50. By having the locking element 42 in the shut-off position, fluid, in particular water or slurry 16, can thus be retained in the suction line 28 and the suction pump 30 at the beginning of the creation of a cutting trench 14 in the ground 12 and thus keeping these components free of air. FIG. 2 illustrates the cutting trench 14 to be created in a dashed line.
At the beginning of the method according to the invention, a shallow guide trench 18 is first created in the ground 12. The guide trench 18 is configured in such a way, that its depth corresponds approximately to the diameter of the cutting wheels 24. The guide trench 18 can be created by a discrete construction machine, such as an excavator.
At the start of cutting, it must be ensured that the suction pump 30 does not draw in any air and thus runs dry. To prevent this, the guide or conduct trench 18 is filled with slurry 16. The diaphragm wall cutter 20 is inserted with its lower portion into the guide trench 18 before the start of cutting, wherein the suction nozzle 26 and preferably also the shut-off device 40 with the locking element 42 in the shut-off position are immersed in the slurry 16, as is illustrated clearly in FIG. 3 .
In this process, a cavity within the suction nozzle 26 may fill with slurry 16 from the guide trench 18, wherein air in the suction nozzle 26 is largely displaced by the slurry 16.
In this initial position according to FIG. 3 , the cutting wheels 24 can now be induced in rotary motion for removing ground material. Simultaneously with or timely to this, the shut-off device 40 can be actuated so that the locking element 42 is returned from the shut-off position back again to the opening or flow position. Simultaneously with or promptly to the resetting of the locking element 42, the suction pump 30 can be actuated so that it suctions in slurry 16 from the forming cutting trench 14 together with milled-off ground material and discharges it upwardly via an upper discharge line 32. In particular, before the shut-off device 40 is opened, the suction pump 30 is started. If a required negative pressure is established above a certain rotational speed of the suction pump 30, the shut-off device 40 can be opened. After a constant circulation of liquid has been achieved, the cutting operation can be started.
The diaphragm wall cutter 20 can now be sunk in this position until the desired final depth of the cutting trench 14 is reached. After an end of the suction and the rotational driving of the cutting wheels 24, the locking element 42 can be returned to the shut-off position so that the diaphragm wall cutter 30, after the retraction from the cutting trench 14, can then be inserted into a guide trench for the creation of another cutting trench at a new cutting location.
As an alternative or in addition to the shut-off device 40 with the adjustable locking element 42, the existing suction openings 27, which preferably have a circular diameter, can each be closed on the suction nozzle 26 by means of a closing cover 44, preferably made of a rubber material, as shown in FIG. 5 . With this arrangement, an interior space or cavity of the approximately wedge-shaped suction nozzle 26 can also be filled with liquid before cutting is started. Thus, there is practically no air left in the area of the suction pump 30, the suction line 28 and the suction nozzle 26. This permits particularly considerate operation of the suction pump 30.
When the suction pump 30 is started up, the suction pressure is adjusted so that the closing covers 44 detach from the suction openings 27 and are suctioned-off together with slurry 16.
According to FIG. 6 , a possible circuit arrangement 10 for operating a diaphragm wall cutter 20 according to the invention with a suction pump 30 is shown strongly schematically. At the beginning of the method, the diaphragm wall cutter 20 is placed in a manner known per se into a previously created guide trench 18, which is filled with liquid.
For normal cutting operation, the suction pump 30 is connected via a line L1 to a treatment unit A for treating the extracted supporting liquid, wherein cutting particles can be separated from the supporting liquid in the treatment unit A in a defined manner. By means of a pump P, the treated supporting liquid is returned again to the guide trench 18 or the created trench via a line L2 and L4 in normal cutting operation.
For performing the method according to the invention, an intermediate line L3 is connected in-between line L1 and L2. For filling the system, a first control valve V1 in line L1 can be closed and a second control valve V2 on line L2 can also be closed. This allows supporting liquid to be directed to the suction pump 30 on the diaphragm wall cutter 20 via the pump P via the intermediate line L3 with an open control valve V3 via the line L1. In this way, the suction pump 30 and the associated line system can be filled before the suction pump 30 is started. In this state, a further, optionally provided control valve V4 on line L2 can also be open.
To start the suction pump 30, the control valve V3 in the intermediate line L3 can be closed. At the same time, control valve V1 on line L1 and control valve V2 on line L2 are opened so that the normal supporting liquid circuit can be set immediately when the suction pump 30 starts up.

Claims

1. Diaphragm wall cutter for cutting a cutting trench in the ground, comprising

a cutting frame,

at least one rotatably-drivable cutting wheel which is mounted on a lower side of the cutting frame,

a suction nozzle which is arranged in the region of the at least one cutting wheel and is provided with at least one suction opening, and

a suction pump which is configured for suctioning slurry out of the cutting trench during cutting via the suction nozzle, wherein the suction pump is connected to the suction nozzle via a suction line,

characterized in

that at least one filling port for filling the suction pump and the suction line with a liquid is provided, wherein the suction line and the suction pump are filled with liquid for starting the suction pump.

2. Diaphragm wall cutter according to claim 1,

wherein

a shut-off device is provided, by means of which the suction line can be shut-off downwards to the cutting trench, and

that the shut-off device comprises a locking element which is mounted in a manner adjustable between a shut-off position and a flow position.

3. Diaphragm wall cutter according to claim 2,

wherein

the locking element is adjustable, in particular displaceable or pivotable, between the shut-off position and the flow position by means of an actuating drive.

4. Diaphragm wall cutter according to claim 2,

wherein

the locking element is arranged on the suction nozzle or on the suction line.

5. Diaphragm wall cutter according to claim 2,

wherein

the shut-off device comprises at least one closing cover which can be loosened when the suction pump starts up.

6. Diaphragm wall cutter according to claim 5,

wherein

the at least one closing cover is configured as a one-way element which can be released by extraction when the suction pump starts up.

7. Diaphragm wall cutter according to claim 5,

wherein

the closing cover is formed with a degradable material, in particular a biopolymer plastic.

8. Diaphragm wall cutter according to claim 1,

wherein

the filling port is arranged at or above the suction pump.

9. Diaphragm wall cutter according to claim 1,

wherein

a filling pump is provided, through which a defined quantity of liquid can be supplied for filling.

10. Diaphragm wall cutter according to claim 1,

wherein

liquid can be supplied into the suction pump and the suction line prior to start-up of the suction pump, when the suction line is open downwards, in a quantity such that said line and pump are filled for starting the suction pump.

11. Diaphragm wall cutter according to claim 10,

wherein

a control device is provided, which is configured to stop filling when the suction pump is started.

12. Diaphragm wall cutter according to claim 11,

wherein

the control device directly controls the filling pump and/or a valve device at the filling port.

13. Diaphragm wall cutter according to claim 1,

wherein

a display device is provided, which displays a filling state of the suction pump.

14. Method of cutting a cutting trench in the ground by means of a diaphragm wall cutter according to claim 1,

wherein

that the suction pump and the suction line are filled with a liquid via the filling port before the suction pump is started.

15. Method according to claim 14,

wherein

a guide trench is created, which is filled with slurry, and

that the diaphragm wall cutter is inserted into the guide trench for cutting, wherein the cutting operation is started even before the suction pump is completely immersed in the slurry.

16. Method according to claim 14,

wherein

that the suction line is shut-off downwards to the cutting trench by means of a shut-off device prior to the start of cutting, and

that the shut-off device is opened when said device is immersed in the slurry, wherein the suction line is filled with liquid.

17. Method according to claim 14,

wherein

that the shut-off device is opened when the suction pump has reached a rotational speed required for suctioning or built-up a negative pressure required for extraction.

18. Method according to claim 14,

wherein

that liquid is supplied into the suction pump and the suction line by means of a filling pump, when the suction line is open downwards, in a quantity such that the suction pump and the suction line are filled when the suction pump is started.