EP1264048A1

EP1264048A1 - Drilling apparatus for hard ground

Info

Publication number: EP1264048A1
Application number: EP01913930A
Authority: EP
Inventors: Jean-Claude c/o Compagnie du Sol Gessay; Philippe C/o Compagnie du Sol Chagnot
Original assignee: Compagnie du Sol SARL
Current assignee: Compagnie du Sol SARL
Priority date: 2000-03-13
Filing date: 2001-03-06
Publication date: 2002-12-11
Also published as: FR2806112B1; FR2806112A1; US20030074810A1; CA2403184A1; US6839988B2; WO2001068990A1; JP2001288773A

Abstract

The invention concerns an apparatus for drilling trenches in the ground comprising a main frame (10) with two main vertical surfaces (32, 32'), a drilling assembly (18) including a support arranged at the lower part of said frame, and means (28, 30) for displacing in vertical translation said drilling assembly relative to said main frame by applying a predetermined force to said drilling assembly relative to the main frame and means anchoring the main frame on the walls of said trench. The anchoring means, mounted on said main surfaces, comprise a plurality of deformable elements (40) integral with said main surfaces (32, 32') of the upper frame (10), and means for injecting a pressurised fluid into said inflatable elements whereby said inflatable elements apply a force between said main frame (10) and the walls of the trench and means enabling said pressurised fluid to be ejected outside said inflatable elements whereby no force is transmitted.

Description

"Rig drilling rig"

The subject of the present invention is a drilling device using a milling cutter for digging trenches in the ground and in particular in soils having a high hardness.

The trench drilling apparatus most often using two cutters are well suited to the realization of trenches of great depth and relatively reduced width. However, when the apparatus has to carry out drilling in hard or very hard soil such as stone, these conventional machines may prove to be insufficient. The milling cutters currently used for cover areas have a maximum weight of 60 tonnes. These devices being suspended from the end of lifting cables, their own weight is transmitted to the cutters to carry out the drilling. However, in these lands, it turns out that the load necessary to obtain a correct drilling is in a range of 100 to 150 tonnes or even beyond. This force depends on the number and type of tool mounted on the wheels of the cutter.

The simplest solution to increase the weight of the device is to load the frame of the cutter. However, this would entail the use of a higher capacity carrier, which of course has significant drawbacks with regard to the organization of the site.

To remedy this drawback, there has already been proposed in the French patent application 2,749,333 in the name of the applicant a particular type of drilling machine using a bur allowing the drilling of trenches in hard soil.

In Figure 1 attached, there is shown in elevational view the drilling apparatus described in the document mentioned above. It comprises a main frame 10 which is suspended from the end of a block 12 itself passing over a lifting mast. The main frame 10 has two vertical main faces, only the front face 14 being visible. The apparatus also comprises a drilling assembly 16 movable in vertical translation at the lower end of the main chassis 10. This drilling assembly 16 essentially comprises a support structure 18 on which is mounted a pump 20 for resuming the flow of liquid d drive of the drilled cuttings, this pump 20 being connected to a flexible discharge pipe 22. The drilling assembly also comprises two rotary cutters 24 and 26 secured to drums driven by hydraulic motors fixed on the support assembly 18. L support 18 can be moved relative to the main frame 10 by means of jacks 28 and 30 which allow on the one hand the relative movement of the drilling assembly 18 relative to the main chassis 10 and on the other hand to apply to the drilling assembly an additional force when the main chassis 10 is anchored in the trench in progress drilling. To achieve this anchoring, the main frame 10 has two pads, only the pad 30 being visible. These pads can be moved away from the chassis using for example jacks in order to anchor the main chassis in the trench.

Such an arrangement effectively increases the force applied to the cutters 24 and 26 in order to allow them to drill in very hard ground. However, given the relatively small dimensions of the active surface of the pads 32 and the large force that must be developed to ensure the anchoring of the upper frame, the pressure exerted by these pads on the walls of the trench is very high. If the trench at the skids is made of a very hard material such as rock, this pressure is acceptable. On the other hand, if the skates are in a transition zone between relatively loose cover areas already drilled and the rock, it is impossible to mobilize with the skates 32 the effort necessary for achieving effective anchoring.

An object of the present invention is to provide a drilling device of the rotary cutter type which effectively makes it possible to drill a trench even in very hard soil and in particular in the case where the soil has a significant transition zone between relatively soil furniture and very hard floor.

To achieve this object, according to the invention, the apparatus for drilling trenches in the ground comprises an upper main chassis having two vertical main faces, a milling assembly comprising a support disposed at the lower part of said chassis, and means for causing a displacement in vertical translation of said milling assembly with respect to said main chassis by applying a predetermined force to said milling assembly with respect to said main chassis and means for anchoring the main chassis on the walls of said trench, said means being mounted on said main faces. The apparatus is characterized in that the anchoring means comprise a plurality of deformable elements integral with said main faces of the main chassis, and means for injecting a pressurized fluid into said inflatable elements, whereby said inflatable elements apply a force between said main frame and the walls of the trench, and means for allowing the exit of said pressurized fluid from said inflatable elements whereby no force is transmitted between said main frame and the walls of the trench. It is understood that, thanks to the presence of the inflatable elements, the surface of the wall of the trench on which the anchoring elements are supported is large. It is therefore possible to develop sufficient force to obtain a suitable anchoring of the upper chassis of the device without too high pressure being exerted on these walls.

According to a first embodiment, a plurality of bands of elastically deformable material and the edges of which are integral with the main face of the main chassis are arranged on the external face of the inflatable elements, the inflatable elements thus being interposed between the band and the main face of the main chassis.

Thus, one obtains on the one hand a mechanical protection of the inflatable elements and on the other hand the transformation of the horizontal force developed by the inflatable elements into a vertical component making it possible to compensate for the force applied by the jacks on the milling assembly . In addition, due to the possibility of deformation of these strips, they can conform to the geometric inequalities of the wall of the part of the trench already drilled.

According to a second embodiment, a rigid plate connected to the main face of the upper chassis is arranged opposite the faces of the inflatable elements facing the wall of the trench. Under the effect of their swelling, the inflatable elements transmit to this plate the force resulting from their internal pressure.

This embodiment has the advantage that the anchoring force is transmitted to the wall via the rigid plate which has a large surface area, which makes it possible to further reduce the pressure for a given anchoring force.

Other characteristics and advantages of the invention will appear better on reading the following description of several embodiments of the invention given by way of non-limiting example. The description refers to the appended figures, in which: - Figure 1 already described is an elevation view of a known drilling rig;

- Figure 2 is a simplified side view of a first embodiment of the drilling apparatus according to the invention;

- Figures 3a and 3b show a first embodiment of the inflatable elements in their respectively inflated and non-inflated state; and - Figures 4a and 4b show a second embodiment of the inflatable elements respectively in their inflated state and in their non-inflated state.

Referring first to Figure 2, we will describe the main elements of the drilling rig according to the invention. This figure shows the upper main frame 10 of the drilling rig with its main faces 32 and 32 '. The drilling assembly 18 has also been represented symbolically with its cutters 24, 26 connected to the main chassis 10 by the vertically acting jacks 28, 30. According to the invention, on at least part of the main faces 32 and

32 'of the main frame 10 are fixed inflatable elements such as 40. These inflatable elements are for example the entire width of the main faces and are arranged substantially side by side. Each inflatable element 40 is constituted by an inflatable cushion limited by a wall made of a tight and elastically deformable material 42. Each deformable cushion is fixed by one of its faces 42a to the main face 32 'of the main chassis and is connected to an individual tube. inflation 44 itself connected to a main inflation tube 46. These tubes may include adjustable pressure limiters to control the value of the anchoring force. According to this first embodiment, each airbag 40 is covered by a strip 48 of a reinforced rubber element whose edges 48a and 48b are anchored in the wall 32 'of the upper chassis. In this figure, one also shows one of the walls 50 of the trench being drilled. It is understood that, when a pressurized fluid, preferably a liquid, is injected into the inflatable elements 40 through the tubes 44 and 46, the inflatable element increases in volume and presses the strip of rubber material 48 against the wall 50. The pressure prevailing in the inflatable element 40 develops against the wall 50 of the trench a force of horizontal component F which is converted into a vertical anchoring force F '. It is understood that by having a sufficient number of inflatable elements 40 on the main faces, it is possible to obtain a very high total vertical anchoring force without the pressure applied by the inflatable elements via the deformable bands 48 being high. A sufficient anchoring effect is thus obtained even if the nature of the material in which this part of the trench has been drilled has limited mechanical strength. On the other hand, as shown in FIG. 3b, when the inflatable element 40 is no longer under pressure, the strip 48 is spaced from the internal wall 50 of the trench and the drilling rig can be moved to drill a new trench section.

Referring now to Figures 4a and 4b, we will describe a second embodiment of the anchoring means. These consist of inflatable elements 40 consisting, for example, of airbags identical to those shown in FIGS. 3a and 3b. These cushions 40 are fixed by one of their faces to the wall 32 ′ of the main chassis and connected to the pipes for pressurized fluid. According to this second embodiment, a rigid plate 60 covering the entire surface occupied by the inflatable elements 40 is made integral with the wall 32 'by an articulated mechanical element 62. The mechanical element 62 which consists for example of a connecting rod or more precisely a plurality of connecting rods is disposed above the upper airbag 40a. It is understood that, when the inflatable elements 40 are effectively inflated, the rigid plate 60 is applied with pressure against the wall 50 of the trench. One can thus obtain a high anchoring force while inducing in the wall of the trench a limited pressure due to the fact that it is the plate 60, which has a large surface, which is applied continuously on the wall of trench.

Claims

1. Apparatus for drilling trenches in the ground comprising a main chassis having two vertical main faces, a milling assembly comprising a support disposed at the bottom of said chassis, and means for causing a displacement in vertical translation of said milling assembly by relative to said main frame by applying a predetermined force to said milling assembly relative to said main frame and means for anchoring the main frame to the walls of said trench, said means being mounted on said main faces, said apparatus being characterized in that the anchoring means comprise a plurality of deformable elements integral with said main faces of the upper chassis, and means for injecting a pressurized fluid into said inflatable elements whereby said inflatable elements apply a force between said main chassis and the walls of the trench and means for allowing the exit of said pressurized fluid from said inflatable elements whereby no force is transmitted between said main frame and the walls of the trench.

2. A drilling rig according to claim 1, characterized in that a mechanically strong and mobile layer under the effect of the swelling of the inflatable elements is arranged on the face of the inflatable elements facing the walls of the trench.

3. A drilling rig according to claim 2, characterized in that said movable layer is constituted by a plurality of bands of elastically deformable material whose edges are integral with a main face of the main frame, at least one inflatable element being interposed between said strip and said main face.

4. A drilling rig according to claim 2, characterized in that said movable layer is constituted by a rigid plate connected to said main face by mechanical means allowing movement of said plate in a direction orthogonal to said main face, said inflatable elements being interposed between said main face and said plate.

5. A drilling rig according to any one of claims 1 to 4, characterized in that said inflatable elements are air bags made of a waterproof and elastically deformable material.