DE2061106A1 - Rotary cutter excavator and dredging method - Google Patents

Description

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Dr. F. Zumstein Sr. ■ Dr. E. Assmann -.UOI IUD Dr. R. Koenlgsberger - Dipl.-Phys. R. Holzbauer - Dr. F. Zumstein Jun.

PATENT LAWYERS

TELEPHONE: COLLECTIVE NO. 226341

TELEX 529979

TELEGRAMS! ZUMPAT

CHECK ACCOUNT: MUNICH 61139

BANK ACCOUNT: BANKHAUS H. AUFHÄUSER

8 MUNICH 2,

BRÄUHAUSSTRASSE 4 / III

4 / Sc

Case G / 551

Takenaka Konmten Co., Ltd., Osaka-shi, Osaka-fu

Japan

Rotary cutting dredger and dredging process.

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The invention relates to a rotary cutter excavator and in particular such an excavator, in which rotating cutters, those at the same speed in opposite Direction rotatable, are provided at the front end of a box-shaped housing, which is its lower side is open and is built in such a way that the dredged soil is brought to the surface with muddy water and an excavation process, which used such an excavator to dig a rectangular deep trench or hole with high efficiency and Dredge stability. -

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The excavator according to the invention is for use in planned a dredging process using a soil stabilizing solution (sometimes referred to as muddy water) such as z. B. a bentnite solution is used, and is provided with a dredging device for the sludge water that is through the solution is causing it. The circumferential walls of the rotating cutterbar form an excavator chamber (excavator section), which is essentially completely closed by a housing or the like. The liquid (muddy water) in the dredging chamber and the outer fluid (i.e. the stabilizing fluid that is in the dredged pit _ is filled), are insulated and separated from each other in order to prevent the exchange of both fluids and the To suppress mobility of the stabilizing fluid so that it is essentially static State is maintained, and the stabilizing liquid is very effective in stabilizing the trench walls causes.

Furthermore, according to the invention, a construction is created, in the case of an excavation device with rotating cutting units and a ground conveyor device for conveying the excavated material Soil, which includes sludge water, is completely separated and independent with the help of a carrier fluid system are to fully meet the purpose of the invention and the Baggerkapazi, ity to double.

According to the invention, the dredging device uses a rotating cutting device in which a pair of rotating cutting units rotate in opposite directions, whereby the torques during dredging cancel each other out and a deviation of the dredger is excluded and the dredging accuracy is increased, so that stable, noiseless and vibration-free dredging is possible will.

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The floor conveyor device is characterized by that immediately below the opening of the bottom conveyor pipe, which has a bell-shaped shape, an upwardly directed one Nozzle is provided, with a high-speed jet from the nozzle transporting the muddy water that is the Contains excavated soil, causes an area in the opening of the soil conveyor pipe * where it can be sucked in, and that by adding the energy of the beam, the absorbent area of the floor conveyor increases can be to create a sufficiently large floor pumping capacity.

According to the invention, the penetration force of the excavator (especially the frictional resistance and the excavation force) are reduced by the use of sliding cutting units, and that Dredging the trench is carried out so that a rectangular one Trench is formed with a geometry that is substantially equal to the length and width of the Machine is, the cutting action of the sliding cutter enables the formation of trench walls with great evenness. ·>.

The vertical accuracy of the dredged trench is naturally high enough to maintain the required accuracy (more than l / 25o).

The most difficult problem, usually with building connected by underground walls is the excavation of the trench for erecting the wall body. The main problems are, how should a ground of different soil types be dredged effectively, how should the dredged one

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Soil quickly to the surface and how is the stability of the dredged trench to be maintained until the concrete is poured. One of the solutions is a muddy water dredging process, which is a soil stabilizing Solution such as B. used a bentnite solution.

There's a new trend, the underground continuous Walls not only to be used as water-repellent walls, but also as earthquake-proof walls to be used in the future or as foundation walls for buildings. For work in or near cities, the Bagger / 7 is ideal for numerous functional restrictions imposed from the point of view of damaging the public from vibration and Noise must be prevented.

So far, many devices have been developed for machines that are used to dig such trenches or the like, determined depending on the type of soil, the depth of the trench or the environmental conditions (external conditions) Have modes of action, but in general their dredging section has both functions, both that of dredging and that of haulage, as is typical for a backhoe you can see. Therefore, their dredging operation is not continuous and the dredging capacity is extremely low. The biggest The problem that is observed with machines of the above type is that the excavator part interferes with the stabilizing Liquid moved into it and thereby eddy currents or Flow movements generated in the stabilizing liquid, whereby a sufficient stabilizing effect on the trench walls is prevented. Since the dredging of this type is not effected by cutting the subsoil, but by destroying the subsurface by the impact force of the

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Excavator part and by tearing off the subsoil a strong noise and vibration generated, which in turn is a cause of public harm.

In summary, the following requirements for an ideal excavator can be established:

I) 'When continuously digging a deep trench with a rectangular cross-section, the z. B. used as casing for an underground continuous wall can be, the excavator must dig a trench of rectangular cross-section from the start with precisely adjustable predetermined Can dredge big ones.

2) He has to dredge and dig the soil without the trench walls to destroy. Stretching the stabilization of the trench walls by a bentnite solution should of course be carried out and the dredging and ground handling operations should not cause movement of the solution and the Do not reduce the possibilities for stabilizing the trench wall. For this purpose it is preferable that the excavator device and the ground conveyor device are independent of each other and that the soil is conveyed by suction or ejection using a Fluids is carried out.

3) The dredging device may remove the surrounding subsoil do not damage or knock it.

4) Accordingly, the excavator must not generate any damage or noise on its own (for this purpose, a rotary cutter excavator to be ideal).

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5) The excavator needs to continuously move the dredged soil quickly and extremely effective operation to the surface.

6) It should allow a sufficiently high level of accuracy in the work. For vertical accuracy this is up to necessary to such an extent that the accuracy required for a building wall (more than 1 / 25o) is maintained and that such a flat trench wall is obtained / that a subsequent reworking of the introduced concrete surface is not necessary.

7) The dredger must have a sufficiently high dredging yield and dredging ability.

8) It should be noted that the above requirements are not are only important for digging a trench for the construction of a continuous underground wall, but also for a general purpose excavator.

The inventive excavator was designed to do all of the above to meet the specified ideal requirements.

In the following, preferred embodiments of the invention are explained in more detail as examples with reference to the accompanying drawing, in which

Figure 1 is a side view in section showing the details of the construction of the excavator according to the invention.

Figure 2 is a front sectional view of the same excavator.

FIG. 3 shows a floor conveyor using a nozzle jet.

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Figure 4 is a developed view showing the arrangement the excavator knife of a rotating cutting unit shows.

Figure 5 shows a representation of the relationships between the excavator and the devices and equipment connected to it. directions required to operate the excavator. · ■ ·

Figures 6A, 6-6 and 6C show the simplest type of dredging using the excavator according to the invention.

FIGS. 7A and 7B show the possibility of digging through the rotating cutting mechanism.

FIGS. 8A to 8D show a newly developed excavator system for a rotary cutter excavator.

FIGS. 9A to 9C show an example of an excavation process.

In the following description, the excavator according to the invention initially described by its main parts, that is a main frame, a rotating cutting unit, drive devices, a floor conveyor and a sliding cutter, and then the process of dredging along with the possibilities described for an operation of the excavator.

A housing 11 of a main frame has I-shaped steel beams built in to have sufficient strength and rigidity against the penetration force and the dredging resistance, and it is constructed in a box shape with iron plates attached to its side surfaces. Just the bottom of the box is open to which a pair of rotating cutting units 14 and 15 are mounted opposite to each other are.

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As will be described later, each of the rotary cutting ' works 14 and 15 on a drum surface in a fixed MusteryÖagger knives attached, consisting of a set of front knives 12 and rear knives 13 exist. The cutting units rotate in the opposite direction the same speed so that the excavator torques generated by the cutting units cancel each other out and the force in the Balance is maintained. The cutting works are designed so that the mud water containing the dredged soil is brought into the space between the two cutting units.

When attaching the cutters 14 and 15, a problem arises in the construction of the bearings; H. in the position of the shaft sealing device and bearings because of the static pressure of the stabilizing liquid, which is proportional to the depth of the trench increases. B. the bearing protrudes outward from the outside of the housing 11, interferes it necessarily the intrusion of the machine. On the other hand, if it protrudes inward, the width of the knife becomes of the cutting mechanism 14 or 15 is too small in comparison with the width of the housing 11, and many disadvantages arise from this. As shown in FIG. 1, according to the invention, a Shaft 16 against the housing 11 and is on this z. B. fastened by welding and the rotating cutting units 14 and 15 are mounted freely rotatable about this shaft 16. With 17 a drive device is referred to, which in a position relative is mounted high up in the housing 11. To the pair of rotating cutters 14 and 15 with a constant To rotate at the same speed with the same torque, two oil pressure motors 18 and 19 mesh with two intermediate gears 2o and 21 one, to their torque, on main sprockets 22 and 23 of the ,, output shaft to transmit. The drive device 17 is characterized in that, although it is a

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The problem is. How the shaft sealing device for the static pressure of the muddy water should be constructed, as the present machine is when dredging with muddy water is used, the output shafts of the oil pressure motors 18 and 19 through a seal chamber on the side where the Effect of the oil pressure is lower, including in which chamber the gear trains are attached to the driving force to be transferred to the main sprockets 22 and 23, so that a sufficient shaft seal on the layer parts the main sprockets 22 and 23 is enabled. For example, if the depth of the dredged trench is 30 m, the static pressure of the muddy water reaches about 3.24 kg / cm (Bentnite solution has a specific gravity of I, o7 to I, o8).

The main sprockets 22 and 23 drive intermediate shafts 24 and

25 by RoHenketfcn 24A and 25A, and rotating cutting units 14 and 15 by other roller chains 26 and 27 via corresponding power transmission devices and under the same Operating conditions. To avoid that the parts fail Can be dredged that the width of the roller chains

26 and 27 there are provided excavator knives comprising a set of front knives 28 and rear knives 29 to form a chain cutter. Ä

Details of the excavator mescer are now to be seen with reference to FIG be described. The front knives and the back knives as they are here designated are as follows; the front sacristans have a small knife width and can go deep into the Cut into the ground while the rear knives have a large measure of width and scrape off the ground that passes through the front knife is incised and made unstable,

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whereby the subsoil is not destroyed during excavation, but completely cut up.

As can be seen from Figures 1 and 4, the rotating Cutters 14 and 15 mounted in their middle parts sprockets to receive the driving force from the oil pressure motors. The excavator knives attached to the left and right parts 14A and 14B of the cutter 14 and the chain cutter are attached symmetrically, determine the entire knife width 1, . The excavator knives of the rotating cutterbar 14 are arranged at a rotation angle of _7T_, and the front

Ren knife 12 and the rear knife 13 are all alternately

Angle of ¹ Tf arranged. One turn of the cutting 2

drum can carry out a uniform dredging over the entire width of the knife 1. The excavator knives of the chain cutters 26 and 27, on the other hand, are arranged so that they are each at angles of Jl with respect to the arrangement of the

The excavator knives of the rotating cutting units are located.

With 3o in Figures 1 and 2 is a sliding cutter referred to, which is attached to the underside of the housing 11 to allow its movement up and down. The sliding cutter 3o closes at its lower end a cutting knife 3oa formed with an edge having an inwardly sloping surface. The cutting knife 3oa follows the leading rotating one Headers 14 and 15 with a fixed trailing stroke to clear undrilled soil in the dredged trench abrading, which can be abraded by the rotating cutting units 14 and not, and thereby creates an external level trench wall, at the same time it pushes the abraded

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Ground to the rotating cutting units 14 and 15 away to to facilitate the operation of the excavator. On the sliding Cutting unit '3o, supports 32, 32 are attached, which are attached through windows 31, 31 which are on the side of the housing 11 are formed, the piston rods of the working cylinder 33, 33 are coupled to this carrier in order to connect them effectively.

The cutting knife 3oa of the sliding cutter 3o is constructed in such a way that there is a small component of the penetration resistance. And mainly through the component of the '™ Cutting resistance can cut.

The rotating cutting units 14 and 15 are in accordance with the invention shaped so that they have a constant differential height am Give cutting ground and also a differential height with a constant knife width in order to achieve a so-called combined To create a front knife 3o-A and a rear knife 3o-B, and thereby enable a smooth cutting of the bottom. At the same time, the sliding cutting device 3o surrounds the parts on which the rotating cutting units 14 and 15 are located are located, and together with a cutter housing described later, determines a closed excavator chamber, and φ acts in such a way that it separates the flow of muddy water in the dredging chamber from the river.

The floor conveyor is described at the end. In Figures 1 to 3 are 34a and 34b cutter housing denotes the length of the knife-tip circular path of the left and right rotary cutters 14 and 15 are attached. Their middle parts recede to so-called bell-shaped Openings * to form, and they are connected to a floor conveyor pipe in connection. The cutter housings 34a and 34b

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are divided between the Ketitenschneidewerke 26 and 2 7, and the bottom delivery pipe 8, which is connected to a suction pump 8a (FIG. 5), also divides at its lower section in two tubes 8 ^ A and 8-B of equal diameter, which each individually connected to the housings 34a and 34b »

In FIGS. 2 and 3, upwardly directed nozzles are designated by 35a and 35b, which are 'directly below the openings of the Bottom conveyor pipe 8 are provided. The nozzles 35a and 35b are rotated by the rotating cutting units 14 and 15, to jets of high velocity from the ground to the muddy water to send, which contains the dredged soil and is collected in the central part, to the mud water to the absorbent surface of the opening of the bottom conveyor pipe 8 to transport. As can be seen from Figures 2 and 3, the nozzles 35a and 35b are depending on the structure of the Schneidewerkgehau.se 34a, 34b and the floor conveyor pipe 8 separately on a Dfiseilbefestigung 36 attached, which is fixed transversely in the housing 11 s: "tst. With the water supply openings 37 are pipes 7-A and 7-B of the same diameter connected, which are stacked in the lower part of an exhaust pipe 7, which with an Aucctos pump 7a (Figure 5) is connected. With 38 and 39 Leitschaufcln are designated for regulating the flow.

The distribution of the suction energy in the opening of the bottom pipe due to the performance of the suction pump 8a (Figure 5) increases with an inverse function of the Abslandes from the pipe opening. An effective floor promotion cannot be expected from centrifugal force alone, which is given to the sludge water by the rotating cutters 14 and 15. Especially when the depth of the dredged Dig an effective high pumping stroke of the pump

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exceeds, the effect of the suction approaches O.

For the sake of simplicity, the liquid, ^ speed Vo, required to move the ballast not converted to sludge, by the following general formula expressed v / earth:

^Vo = / JL · '■ q ■ ^d

where g: acceleration due to gravity

c: 1.4 if Re> looo

X: Loss factor of the inside of the pipe

d: Ba 11 a s t dur cn me s s er

S: A constant for the ballast.

From Bernoulli's theory it is clear that if a certain energy (kinetic energy, pressure energy, potential Energy) in the fluid in the opening of the bottom delivery pipe, the effective high pumping stroke of the suction pump and therefore the; absorbent «area of the opening of the floor conveyor pipe

the suction pump can be enlarged. Ä

In the case of the machine according to the invention, it can be said that there is a centrifugal force caused by the rotating cutters 14 and 15 and a jet flow through the nozzles 35a and 35b that generate the above energy.

The mode of action and operation of this jet flow can also be clarified as follows:

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Assume that Qj is the flow rate of the jet flow Qs is an average flow rate in the bottom conveyor pipe 8 and Qf is a flow rate of the flow passing through the rotating Cutting works is set in rotation and flows in from the circumference of the jet flow, then the equation becomes Qs = Qj + Qf derived in accordance with the experiment.

It should be particularly noted that as Qj gradually increases in the above equation, a range exists in which <} s suddenly increases, (er. it is assumed that this can be explained from Bernoulli's energy equation) and Qf increases accordingly. Because, since the fluid coming from the Urnfancj the jet flow flows inward, which is mud water containing the dredged soil, becomes the possibility of soil pumping created when the flow rate Qf increases and therefore the velocity of the flow becomes the velocity Vo of the above equation. This can can be freely regulated by adjusting the flow rate Qj of the nozzle. In this case the blades 38 and 39 have the effect of having fluid flow within an area to constrain constant cross-section.

When the efficiency of the soil conveyor is expressed by the volume concentration, the proportion of dredged soil reaches 2o to 3o%. The experimental results show that with a soil conveying pipe 8 having an inner diameter of 150 mm, a block of dredged soil having a longer side of 15 cm and a shorter side of 10 cm was conveyed as it was. This shows the high performance of the machine.

With reference to FIG. 5, the mode of operation of the inventive Excavator and its connection with the facilities,

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which are necessary for operation are described «

1 generally denotes the excavator according to the invention, as described above. It can be carried substantially vertically by a frame 2, which is erected at a fixed point in an installation field. He can gradually by the force of a working cylinder 3 and is guided through the framework 2 in order to excavate a trench or borehole 6.

The sludge water (stabilizing liquid, such as Bentnite Fluid) will, as the dredging progresses, ™ fed from a bentnite mixer attached to a sludge water basin 4 located near the dredging site is arranged, this mixer constantly producing new liquid. With a passage 4 is referred to, which the worn out Trench 6 and the mud pool 4 connects.

The bottom conveyor pipe 8 and the discharge pipe 7 lead as shown into the ground, with them the suction pump 8a and the discharge pump 7a is connected. Next, the bottom conveyor pipe 8 is connected to a sludge water separation system 9, wherein the Suction pump 8a lies in between, this separation system separating the excavated soil from the liquid, which then by a circulation pump 9a of the ejection spur 7a is supplied to the water which is supplied from the nozzle and the water which is conveyed from the bottom conveyor pipe 8 is going to put into circulation.

The dredged soil is further vibrated by a Sieve (not shown), which is part of the sludge * · separation system 9 is, and then to a circulation pump 9b, then to a fluid cyclone 9c and a mixer 9d as a solid,

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completely separated from the water, fed in or led outside as drained soil.

The discharge pipe 7 and the delivery pipe 8 become continuous extended as the dredging progresses «, the frame 2 can be freely moved in the horizontal direction to the Avoid and repeated construction work for the excavator To facilitate dredging work. Io denotes an oil pressure unit, which consists of a control quay for the excavator, the one with an oil pressure powered hoisting mechanism is equipped as described above. This unit enables all types of control «

The following is a deep trench dredging method described, according to the mode of action of the one described above inventive excavator was developed.

As can be seen from Figure 7A, the excavator surface is the inventive excavator built so that it has a rectangular Has shape through the sliding cutter 3o. When the length and width of the excavator area of the excavator (these can be viewed as the length and breadth of the sliding cutter 3o) expressed by a χ b and the dredging process will be easier from one point Repetition of the operation is started, then, if η is the number of repetitions, a trench with the width b and the length η χ a are dredged.

However, if, as is well known, the efficacy? of Takes into account the pressure of the surrounding soil on the dredged trench, this effect gradually increases, as the trench gets deeper and the dimensions (length and width) of the trench increase.

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In the case of the excavator according to the invention, these difficulties be overcome in the following way.

As shown in FIG. 6, the excavation work of the trench is carried out along a predetermined line in a small manner, until a plurality of trench boreholes 40 are drilled, each of these boreholes being at a constant distance a from the next, taking the width dimension a of the excavator as a reference to form discrete boreholes 4o (of course, the length dimension b can be taken instead of a). Then, depending on the progress of the concrete work, the areas 41 which lie undeveloped between the boreholes 4o and 4o are dredged in order to complete a contiguous trench 42 of the desired length L. If, with reference to FIG discrete holes to be dredged of small dimensions, when each is considered in itself, and therefore g greater stability for the ground pressure can be ensured. It is a particularly noteworthy advantage that when the remaining surfaces 41 remaining between the boreholes 40 are dredged, the resistance to penetration acting on the excavator 1 is markedly reduced, and that because the rotating cutters so rotate Then they collect the soil inwards, as shown in FIG. 6C, the dredging work for the surfaces 41 can be carried out without refilling the dredged boreholes 4o at the opposite ones

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Pages is to be feared, from which a simple and effective work results. If work in such a Way is carried out that first individual boreholes 4o are dredged along a predetermined line and then depending on the progress of the concrete work, the bottom between the dredged holes 4o and dredged is promoted, a trench of length L (η χ a) can be carried out at the same time with the dredging of the remaining areas 41 full

^{1 s}

will end. So can the economics of dredging and the foundation work can be considerably improved.

The structure and the mode of operation of the excavator described above will now be discussed again.

The excavator can dig a trench of rectangular shape (a κ b) with high working accuracy with the aid of the sliding cutter 3o and the rotating cutters 14 and 15. On the other hand, it has the following inadequacy: Figures 7A and 7B show the arrangement of the sliding cutting unit 3o and the rotating cutting units 14 and 15, the hatched part K in the center of Figure 7A has poor mechanical dredging ability as shown in Figure 7B fe is seen so that the dredged ground has raised parts corresponding to that part (this is of course not he wishes).

In order to avoid this disadvantage, the following was made according to the present invention Dredging method developed.

In Figure 8A, drill holes 5o, each of which has a diameter substantially equal to the width b of the excavator 1 has dredged along a predetermined line in advance,

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the spacing of this row of boreholes being equal to the width dimension a (or the length dimension b) of the excavator is. The boreholes 5o can be dredged by a pre-drilling machine or any other machine. Then it will be as in the aforementioned embodiment, a variety of discrete trench holes 4o dredged, with undeveloped Areas 41 of length a remain between the boreholes 5o, using a rotary cutter excavator 1 is and its Miüb set on a dredged borehole 5o as shown in Figure 8B, and then depending on the progress of the concrete work, those in between remaining / laughing 41 between the trench bores 4o dredged to complete a trench 42 of length L (η χ a).

When this dredging method is used, an even Dredging can be performed, and the excavation speed can be increased remarkably because the Drill holes 5o on the parts K are carried out beforehand, where the excavator has poor excavation performance, as shown by the dot-dash line in Figure 7B.

Since the boreholes 5o also reduce the dredging resistance that is applied to the rotating cutters 14 and 15 has a considerable effect

ringeirn, the excavator can have the characteristic properties fully demonstrate by enabling stable and extremely precise excavation work.

As stated above, the "mode of operation of the according to the invention-n Baggers ^ a trench of rectangular Gestali: "To be able to dredge it with high accuracy possible to carry out a dredging process that is unique in comparison with the known processes.

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Figure 9Α shows ζ. B. a case where a pillar of T-shaped Cross-section is dredged on the spot. To do this, a trench borehole 61 is made to a desired one Dredged to a depth, the long side a of the excavator being oriented horizontally, and after the excavator has rotated Another borehole is drilled to the desired depth at 90 ° v / with the side edge of the dredger exactly on the middle side wall of the previously dredged borehole Gl is baked. This completes the T-shaped borehole.

By using this procedure, a continuous underground wall that serves as a water barrier can be created, such as is shown in Figure 9B, or trench bores that are perpendicular to long trench bores 63 which the outer wall of a conventional building with high accuracy be dredged.

Fine drill holes with a cruciform cross-section can also be drilled in place, as shown in FIG. 9C is. To do this, two lateral trenches 65 and 65 are dredged, with an area of width b remains between them, and then, after the excavator is rotated 9o, the longitudinal trenches 66 and 66 are included The remaining area in between was dredged to complete the cross-shaped trench.

All of these dredging methods can be due to the fact be carried out that the inventive excavator can excavate a trench of exactly rectangular shape (a κ b) with high accuracy.

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Claims (6)

well ·, hu · ψγ - 21 - P a t e η t a η s ρ r ü ehe ) J excavator for digging trenches, characterized by a box-shaped housing with a main frame that is open at its bottom, by a pair of rotating cutting units, which are mounted in the lower part of this housing, through knives for digging, which are on the outer circumference of cylindrical drums each of these rotating cutters are provided by -Λ a bottom conveyor pipe having a suction port formed by pressing a central upper part of the cutter housings bell-shaped around these rotating cutters, the one dredged by the cutters and knives Soil collected in an intermediate part between these cutters can be sucked through this soil conveyor pipe and conveyed to the soil surface. 2) excavator according to claim 1, characterized by a sliding cutter, which is provided on the circumference of this housing and independently of the work of this housing & carries out an excavation work. ' 3) excavator according to claim 2, characterized by upward directed nozzles, which are attached directly under the suction opening of the floor conveyor pipe and a flow • Point the jet upwards at high speed. 4) excavator according to one of the preceding claims, characterized characterized that the knives for excavating, which on the outer periphery of cylindrical drums each of these 109 826/107 9 BATH ORIGINAL; ^r rotating cutters are provided, from 'sets of Front and rear knives exist that a drive device torques of the same size and opposite Direction of two oil pressure motors transmits through an idler gear device, the rotating one Cutting units are set in rotation by this drive device that the sliding cutting unit that is on Scope of this housing is provided a cutting knife device has, which consists of front and rear knives that working cylinder fixed to the upper part of this Housings are attached, with a piston rod of each cylinder with a support of each sliding cutter is connected to enable dredging to follow the preceding rotating cutting squares can be carried out ^ and that an exhaust pump with these nozzles, which are below the suction opening of the bottom conveyor pipe are mounted facing upwards, is in connection, the by the cutters and Soil excavated by knives and collected in a space between these cutters by means of them The discharge pump can be sucked in through this delivery pipe and delivered to the ground surface. 5) Use of an excavator according to one of the preceding claims for dredging a trench borehole of rectangular Shape given by the length and width dimensions (a χ b) of the excavator is determined, characterized in that discrete and alternating trench boreholes along a predetermined line are dredged, each at a distance equal to the excavator width a or b from next away, and that then the remaining areas between the discrete Trench boreholes, if necessary, to be dredged, 109826/1079 BATH mim »!»! ι H lim - 23 - to form a trench of the desired length. 6) Use of an excavator according to one of claims 1 to 4 for excavating rectangular trench boreholes, characterized characterized in that previous boreholes along a predetermined line at a distance equal to the excavator width a or b of the excavator are dredged that then discrete trench holes for those previous boreholes one at a time are dredged by skipping, f wherein the excavator is centered on these previous boreholes, and that then the between Any areas left over from the discrete trench boreholes are dredged in the same way, if necessary, to form a trench of the desired length. 109826/1079 BATH ORIGINAL It Blank page