EP0826835B1 - Trenching apparatus for digging deep trenches - Google Patents

Description

The present invention relates to an apparatus for digging into the ground very deep trenches.

We already know drilling rigs of the type comprising a chassis suspended by cables from a lifting device, chassis at the bottom of which milling drums are rotated in opposite directions to break up the ground by allowing said chassis to sink into the ground to dig an excavation.

To make a trench in the ground using such a device, we digs a plurality of boreholes aligned in a given direction and brings together these boreholes by eliminating the portions of land that separate them.

For each borehole, a rectangular frame is made on the ground. concrete whose inner section corresponds substantially to the outer section of the chassis, position the chassis inside the frame by resting it on the ground while the milling drums are turning.

The chassis then begins to sink into the ground while being held in its working position by the frame.

When driven into the ground more than its height, the chassis comes out of the frame and is no longer guided downwards except by the part of the trench already made.

From this moment, the chassis progresses in the ground without control precise of its orientation.

At shallow depth, the orientation of the chassis remains suitable, which makes it possible to obtain boreholes which, after meeting, form a continuous trench and substantially flat.

On the other hand, at great depth, about thirty to forty meters from the ground surface, the chassis may tend to follow a path helical, i.e. it can sink into the ground by turning around its vertical longitudinal axis.

This is a major disadvantage because not only the trench thus obtained is not planar, but in addition two neighboring boreholes risk not being able to be reunited due to the too great distance between them, hence a risk of discontinuity in the trench.

We have already proposed push mechanisms mounted on the chassis and which rest on the walls of the borehole to reposition the chassis in the drilling in order to avoid too great a deviation from its trajectory.

However, these mechanisms do not prevent rotation of the chassis around its longitudinal axis.

Furthermore, the applicant company has already written in the patent EP-A-0 592 325 an apparatus for digging trenches in the ground of the same type as above, in which the chassis is further provided with its upper part of a freely pivoting muffle by which it is suspended from the lifting gear. Thanks to this freely swiveling block, the chassis can be oriented by hand before starting an excavation, in particular by positioning it obliquely to the hoist, allowing, by playing on the length and orientation of the mast of the hoist, position the chassis above a guide frame, without having to place the lifting device strictly at the perpendicular to this frame. This is particularly advantageous when want to drill perpendicular to a non-movable obstacle such as a corner of building.

However, this type of freely swiveling muffle device does not solve not the problem of the chassis rotation during its descent into the ground at great depths.

The present invention aims to provide a simple and economical device which resolves in particular the drawback recalled above.

The present invention relates to an apparatus for performing trenches in the ground of the type intended for digging excavations in progress vertically in the ground, comprising a frame provided, at its upper part, with a swivel block for suspension by a cable to a lifting device and, at its part lower, of milling drums able to disaggregate the ground on a section allowing the chassis to pass in the wake of the milling drums, the device further comprising a hose which connects it to the ground surface and serves for evacuation ground debris torn off by the milling drums, characterized by the fact that the swivel block is motorized.

The debris removal hose is also referred to as of mud hose, because the excavation is dug under mud and debris is evacuated by pumping mud in the vicinity of the milling drums.

Thanks to the invention, it is possible to correct any untimely rotation of the chassis in the drilling, due to the fact that the motorized muffle allows to print a torque of rotation to the chassis, by leaning either on the cables which connect the muffle to the lifting device and on the mud hose, possibly only on the muffle cables.

The mud hose, which is usually a six-inch pipe of diameter provided with a frame, in fact provides sufficient support for the motorized muffle of the device according to the invention gives the chassis a couple of rotation to correct the orientation of the device in the excavation.

However, it also turned out that the cables connecting the muffle surprisingly enough for the hoist to cause the pivoting of the muffle subjects the chassis to a torque which causes it to descend by twisting in the drilling.

If such a phenomenon can appear obvious when the chassis does not finds only a few meters from the surface of the ground, where precisely the problem of the rotation of the chassis does not arise, it is quite different when the chassis found at a great depth, for example at thirty or forty meters from the ground surface.

Indeed, it is expected that from a certain depth, a pivoting of the block has no effect on the behavior of the chassis, but only causes the stranding of the cables, because the resistive torque of the cables is inversely proportional to their length.

However, tests carried out by the applicant company revealed that a swivel of the muffle low enough not to strand the cables can nevertheless have an influence on the progress of the chassis by causing its progression in a spin in the direction of the torque imparted by the block.

Thus, to compensate for an untimely rotation of the chassis and bring back the chassis in the plane of the trench to be made, just rotate the muffle so as to impart to the chassis a torque opposite to its direction of rotation.

In a first embodiment of the invention, the muffle is consisting of a simple rotating joint comprising an upper part connected to the lifting gear and a lower part connected to the chassis, the two parts of the joint being axially pivotable with respect to each other, around a connected channel with the mud hose which allows pumping debris pumped in the vicinity of the milling drums.

A motor integral with the lower part of the rotating joint meshes then a toothed wheel secured to the upper part of the rotary joint.

In a second embodiment of the invention, the muffle is constituted by a multiple rotating joint which comprises, in addition to the central channel connected to the mud hose, at least one peripheral annular channel for the passage of the pressurized fluid supplying the chassis motors.

As in the previous embodiment, a motor meshing a gear can be used to rotate the bottom of the seal rotating relative to its upper part.

In a third embodiment of the invention, the muffle is constituted by the structure described in French patent application No. 2,696,758, a motor having been added to motorize the muffle.

Advantageously, the connector which connects the channel to the mud hose is designed to allow axial pivoting of the muffle relative to the flexible mud, so as to release said hose from torsional stresses which may appear when lowering the chassis into the trench.

However, preferably, this swivel connector is locked in rotation, to allow the muffle to rest on the mud hose and on the muffle cables to give the chassis a torque.

The present invention also relates to a method of making trenches using a drilling rig of the type comprising a frame provided with its upper part of a swivel block connected by cables to a lifting machine, chassis at the bottom of which milling drums are driven rotation to break up the terrain by allowing said chassis to sink into the ground, said apparatus further comprising a hose which connects it to the ground surface and is used for the evacuation of ground debris torn off by the milling drums, this process being characterized in that it consists in detecting a possible rotation of the chassis relative to its vertical longitudinal axis and to rotate the block rotating in the opposite direction to that of the chassis rotation to print a torque on the chassis by pressing on the hose and / or cables.

• la figure 1 est une vue en perspective d'un appareil pour creuser des tranchées dans le sol selon un mode de réalisation de l'invention, et
• la figure 2 est une vue en coupe du moufle tournant de l'appareil de la figure 1.

In order to better understand the invention, we will now describe an embodiment given by way of non-limiting example of the scope of the invention, with reference to the accompanying drawings in which:

• FIG. 1 is a perspective view of an apparatus for digging trenches in the ground according to an embodiment of the invention, and
• FIG. 2 is a sectional view of the rotary muffle of the apparatus of FIG. 1.

The apparatus shown in the drawing includes a lifting device consisting of a platform 1 provided with tracks 2, and on which rest in particular an articulated mast 3, a reel 4 for a large mud hose diameter (not shown) for reassembling the cuttings, reels 5 for oil pressure hoses, a winch 6 for the lift cable (not shown), and a device 7 for controlling and monitoring the various organs of the device.

A chassis 8 is suspended by the lift cable (not shown) at the free end of the articulated mast 3, the cable being engaged on a fixed block at the end of the mast and on a motorized swivel block 9 at the top of the chassis 8, which allows the chassis to be oriented in any direction.

This pivoting block 9, which is shown in section in FIG. 2, comprises an upper part 10 intended to be suspended from the hoist and a lower part 11 secured to the chassis, these two parts being pivotable one relative to each other around a vertical axis 12.

The upper part 10 of the muffle comprises two pulleys 13 for the passage of the lift cable 14 and a plurality of connections 15 for hydraulic hoses 16, the whole being mounted on a plate 17 a .

A hub 17 b integral with this plate 17 a extends downwardly defining seven peripheral grooves 18 distributed axially along the outer surface of this hub.

A central channel 19 extends over the entire height of this hub.

The lower part 11 of the muffle comprises a cylindrical body 20 which surrounds the hub 17 b and comprises seven annular grooves 21 of rectangular section on its inner face, opposite the peripheral grooves 18 of the hub, separated by grooves 22 of smaller dimensions which house seals 23 between the grooves.

The grooves in correspondence of the hub 17b and the cylindrical body 20 define peripheral annular channels which are each connected to a connector 15 of hydraulic hose leading to the upper part of the muffle by a specific channel 24 formed in the plate 17 a and in the hub 17 b .

Likewise, these annular channels are each connected to a connection of hydraulic hose 25 leading to the lower part of the block through a channel specific 26 produced in the body 20.

The mechanical connection between the fixed part of the muffle 17 a , 17 b and its rotating part 20 is carried out using an annular bearing 30 whose external ring 32 is integral with the fixed plate 17 a and whose internal ring 34 is secured to the upper end of the cylindrical body 20.

The central channel 19 of the hub extends into the lower part of the muffle and allows the passage of delays pumped in the chassis in the vicinity of milling drums. It is connected to the mud hose 27 by a swivel connector 28 which can be locked in rotation.

More specifically, the axial passage 19 of the hub 17 b is extended by a cylindrical sleeve 36 fixed on the upper face of the plate 17 a .

This sleeve is connected to the lower end 27 a of the mud hose 27 by the pivoting connector 28 integral with the end 27 a and into which the sleeve 36 enters in rotation.

At its lower part the axial passage 19 is extended by a pipe for raising the cuttings, the pipe 38 being integral with the chassis 8. It is not necessary to provide a seal between the passage 19 and the pipe 38 since this assembly is immersed in the drilling mud.

A motor 29 mounted on the body 20 and therefore secured to the lower part 11 of the muffle meshes with a toothed wheel 30 secured to the upper part 10 via the hub 17b in which it is formed and allows, if necessary, to print a torque to the chassis when drilling in the ground.

In normal operation the swivel connector 28 is locked in rotation, the muffle rests on the mud hose 27 and on the different strands of the cable 14 when the motor 29 is actuated to rotate the lower part 11 of the muffle and therefore the chassis 8 relative to its upper part 10.

In some special cases it may be useful to unlock in rotation the swivel joint 28 to avoid the introduction of stresses in the flexible mud.

In all cases, a torque is transmitted to the chassis 8 of the device which then progresses in the ground by turning around its axis 12.

It is understood that the embodiments which have just been described are in no way limiting and that they may receive any modification desirable without departing from the scope of the invention.

Claims (7)

1. Apparatus for making trenches in the ground, of the type provided to dig excavations by advancing vertically in the ground, comprising a chassis (8) provided, in its upper part, with a pivoting block (9) for suspension thereof by a cable (14) from a lifting machine (1-7) and, in its lower part, with milling drums adapted to disintegrate the earth over a section allowing passage of the chassis (8) in the wake of the milling drums, the apparatus further comprising a flexible hose (27) which connects it to the surface of the ground and serves to evacuate the earth debris torn by the milling drums, characterized by the fact that the pivoting block (9) is motorized.
2. Apparatus according to Claim 1, characterized by the fact that the pivoting block (9) is constituted by a simple rotating joint comprising an upper part (10) connected to the lifting machine (1-7) and a lower part (11) connected to the chassis (8), the two parts of the joint being axially pivoting with respect to each other about a channel (19) connected to the hose (27) for evacuating the debris pumped in the vicinity of the milling drums.
3. Apparatus according to Claim 1, characterized by the fact that the pivoting block (9) is constituted by a multiple rotating joint which comprises, in addition to a central channel (19) connected to the debris-evacuating hose (27), at least one peripheral annular channel (18, 21) for the passage of the pressurized fluid supplying the motors of the chassis.
4. Apparatus according to any one of Claims 1 to 3, characterized by the fact that the debris-evacuating hose (27) is connected to the pivoting block (9) by a pivoting connection (28) which may be unblocked in rotation.
5. Process for making trenches with the aid of a boring apparatus of the type comprising a chassis (8) provided in its upper part with a pivoting block (9) connected by a cable (14) to a lifting machine (1-7), in the lower part of which chassis milling drums are driven in rotation in order to disintegrate the earth while allowing said chassis (8) to penetrate in the ground, said apparatus further comprising a flexible hose (27) which connects it to the surface of the ground and serves to evacuate the debris of earth torn away by the milling drums, this process being characterized by the fact that it consists in detecting a possible rotation of the chassis (8) with respect to its vertical longitudinal axis and in rotating the pivoting block (9) in the direction opposite that of the rotation of the chassis (8) in order to impart a torque to the chassis (8) by bearing on the hose and/or on the cables.
6. Process according to Claim 5, characterized by the fact that the pivoting block (9) is blocked in rotation with respect to the debris-evacuating hose (27).
7. Process according to Claim 6, characterized by the fact that the pivoting block (9) is temporarily unblocked in rotation with respect to the debris-evacuating hose (27).

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