Concreting facility and corresponding concreting method

Abstract

The invention relates to a concreting installation for concreting an excavation. The installation includes a concreting column having a top end arranged to be open in order to be at atmospheric pressure, and at least one controlled retention device situated at a distance from the open top end of the concreting column and adapted, in at least one configuration, to retain a volume of concrete inside the column. The invention also relates to a method of concreting an excavation.

Claims

1. A method of concreting an excavation, the method comprising: placing a concreting column in the excavation for concreting, wherein the concreting column extends between an open top end and a bottom end thereof; at least partially filing the concrete column with a fluid other than concrete; and performing a first concreting cycle, wherein the first concreting cycle comprises a priming step comprising: inserting concrete into the concreting column via the open top end to expel the fluid other than concrete from the concreting column; filing the concreting column with concrete; and retaining a volume of concrete a distance from the open top end such that a height of an empty space, defined between the volume of concrete and one of the open top end and the bottom end of the concreting column, remains less than a predetermined limit value, wherein retaining the volume of concrete comprises at least partially constricting a flow section inside the concreting column and/or to the outside of the concreting column.

2. The concreting method according to claim 1, wherein the empty space is situated above the volume of concrete.

3. The concreting method according to claim 2, wherein the first concreting cycle further comprises: measuring and/or calculating at least one parameter representative of the level of concrete inside the concreting column; and at least partially constricting the flow section inside the concreting column and/or to the outside of the concreting column as a function of the at least one parameter to retain the volume of concrete such that the height of the empty space defined between the volume of concrete contained in the concreting column and the open top end of the concreting column remains less than the predetermined limit value.

4. The concreting method according to claim 1, wherein the first concreting cycle further comprises: stopping the introducing of concrete to the concreting column once a given volume of concrete has been inserted into the excavation; and at least partially constricting the flow section inside the concreting column and/or to the outside of the concreting column as a function of at least one parameter representative of the level of concrete inside the concreting column.

5. The concreting method according to claim 1, wherein the empty space is situated beneath the volume of concrete.

6. The concreting method according to claim 5, further comprising discharging air present in the empty space.

7. The concreting method according to claim 1, wherein the predetermined limit value is substantially equal to 40 meters.

8. The concreting method according to claim 1, further comprising: raising the concreting column inside the excavation after the first concreting cycle; and performing a second concreting cycle.

9. The concreting method according to claim 1, wherein the predetermined limit is less than a height of the concreting column between the open top end and the bottom end.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention can be better understood on reading the following description of embodiments of the invention given as non-limiting examples and with reference to the accompanying drawings, in which:

(2) FIGS. 1A to 1D show various steps of a concreting method performed using a concreting installation in a first embodiment of the invention;

(3) FIGS. 2A and 2B show in greater detail the valve member of FIGS. 1A to 1D, respectively in the closed state and in the open state;

(4) FIGS. 3A and 3B show a second example of the retention device that can be used in the invention;

(5) FIGS. 4A to 4C show a third example of the retention device;

(6) FIGS. 5A and 5B show a fourth example of the retention device;

(7) FIGS. 6A and 6B show a concreting installation in a second embodiment of the invention;

(8) FIG. 7 shows a variant of the second embodiment; and

(9) FIG. 8 shows a third embodiment of the invention.

(10) FIG. 1A shows a concreting machine 100 of the invention, adapted for concreting an excavation E as shown, of height H1 that in this example is equal to at least 100 meters and is filled with a drilling fluid F of the bentonite mud type.

(11) The concreting machine 100 comprises a concreting installation 10 provided with a concreting column 12 of axis A, whereby concrete is introduced into the excavation.

(12) It also has a support structure 80 having mounted thereon support and guide means for the concreting column 12, which means in this example are constituted by a guide mast 82, a rotary system 84 that is movable along the guide mast 82, and a device for clamping the concreting column 86, in this example in the form of a double guillotine. Other equipment is mounted on the support structure 80, such as a control unit 90.

(13) In order to reach the desired concreting depth, the column 12 is made up of a plurality of column elements 14 mounted in succession one after another along the axial direction A. By way of example, the connection between two successive elements 14 may be provided by screwing a threaded end of one of the elements into a complementary tapped end of the second element. Such a connection can be made or undone in conventional manner using the clamping device 86.

(14) In FIG. 1A, the concreting column 12, formed by a plurality of column elements 14, is held at its top end by the clamping device 86, while its bottom end is located in the vicinity of the bottom of the excavation E. Its total height H2 is not less than the height H1 of the excavation.

(15) As can be seen in FIG. 1A, the column 12 is open and is fitted with a funnel 16 at its top end, and it is provided with an outlet 18 opening out axially at its bottom end.

(16) In accordance with the invention, the installation 10 has a controlled retention device adapted to retain a volume V of concrete inside the column 12, as described in greater detail below.

(17) FIGS. 2A and 2B show in greater detail the bottom end of the FIG. 1A column 12 fitted with this retention device.

(18) In the example shown, the retention device comprises a valve member 30 mounted to move in translation relative to the column 12 in the axial direction so as to be capable of occupying a closed position in which the outlet orifice 18 is completely shut, an open position in which the flow section through the outlet orifice 18 is at a maximum, and possibly a partially open position in which the flow section is not zero but is smaller than that obtained in the open position.

(19) FIG. 2A shows the valve member 30 in the closed position. It is moved to the open position of FIG. 2B by means of two hydraulic actuators 20 connected to the control unit 90 secured to the support structure. These arrangements are nevertheless not limiting, and the valve member may be actuated by any other appropriate controlled actuation mechanism, in particular electric actuators or cables.

(20) The various steps of a concreting method of the invention using the above-described installation 10 are described below with reference to FIGS. 1A to 1D.

(21) In an initial state, the concreting column 12 is filled with drilling mud F, as is the excavation E. The valve member 30 is in a partially open position, with the flow section through the outlet orifice 18 being small.

(22) FIG. 1A shows the priming stage, which consists in replacing the mud F initially present in the concreting column 12 with concrete.

(23) In order to avoid the concrete being polluted by the mud F during this stage, a plug constituting a priming piston 22 is previously placed at the surface of the mud, inside the column 12. The concrete is thus continuously separated from the mud.

(24) By means of the valve member 30 partially shutting the outlet orifice 18 of the column 12, the flow of mud out from the column 12 is limited, thereby braking the descent of concrete. This serves to avoid concrete segregation phenomena and the resulting plugs. If the outlet orifice 18 were not partially shut, the concrete would descend inside the column 12 in abrupt manner because of the difference in density between concrete and mud, thereby giving rise to the above-mentioned undesirable phenomena.

(25) Once the column 12 is full of concrete, the valve member 30 is put into the open position by the control unit 90 and the excavation E begins to be concreted at a controlled rate.

(26) In FIG. 1B, it can be seen that the priming piston 22 is placed against the top face of the valve member 30, where it is to stay until the end of concreting of the excavation. In this position, the priming piston performs a novel guidance and abutment function for the concrete. Provided with a working top end that is pointed, it breaks up any clusters of gravel contained in the concrete and reaching the outlet orifice 18.

(27) After concrete has filled a predetermined volume of the excavation E, and for a predefined height of concrete remaining in the column, the feed of concrete to the column 12 is stopped.

(28) At this instant, an empty space of height H3 is defined between the top end of the column and the free surface of the concrete inside the column, and the valve member 30 is moved into its closed position.

(29) As shown in FIG. 1C, the funnel 16 is then separated from the top end of the column 12, which is then fastened to the rotary head 84, with the column 12 being raised along the mast 82 through a height substantially equal to the length of a column element 14, and then the element 14 at the top end is removed, and the funnel is put back into place at the top end of the now-shortened column.

(30) Since the valve member 30 is in the closed position, the flow rate of concrete at the outlet from the column is zero, and the height of concrete inside the column remains unchanged.

(31) Once the column 12 is once more held in place in the excavation E by means of the clamping device 86, the valve member 30 is moved into its open position, as shown in FIG. 1D, and concreting is continued.

(32) The concrete poured into the funnel 16 then drops inside the empty space over a height H4 corresponding to the height H3 minus the height of the column element that was reduced when shortening the column. The first concreting cycle is stopped and the valve member 30 is controlled in such a manner that this height H4 does not exceed the acceptable limit height for dropping concrete, which is generally about 40 meters.

(33) The sequence of FIGS. 1C and 1D is repeated as often as necessary in order to concrete the entire excavation E.

(34) During these operations, one or more measurement and/or calculation devices serve to detect one or more parameters representative of the advance of the concreting. These may comprise in particular:

(35) means for measuring the length H2 of the column 12 and the position of its bottom end 12b in the excavation E;

(36) means for measuring the level of concrete inside the excavation E and inside the column 12;

(37) means for measuring the flow rate of concrete and/or of mud inside the column 12;

(38) means for measuring and/or calculating the volume of concrete that has already been inserted into the excavation E; and

(39) means for measuring and/or calculating the forces needed for raising the concreting column 12.

(40) The values obtained for the above-mentioned parameters are advantageously transmitted to the control unit 90, which processes them in order to control the process and which opens and closes the valve member 30 as a function thereof.

(41) In particular, provision may be made for the control unit 90 to include a computer and for it to display continuously a curve giving the height of concrete inside the excavation E as a function of the volume of concrete that has already been inserted into the column. While also taking account of the position of the bottom end 12b of the column 12 inside the excavation E, the control unit can then cause concreting operations to be stopped and can trigger a new shortening of the column, in such a manner that the height H4 that concrete drops in the empty space inside the column, when concreting is restarted, remains less than the predetermined limit value.

(42) It should be observed that although this is not shown, the concreting installation 10 could equally well include a system for handling and storing column elements 14 and/or a system for handling and screwing/unscrewing the funnel 16.

(43) The operations of monitoring and controlling the retention device, of shortening the column, and also of stopping and restarting concreting operations could also be performed manually, by an operator, as a function of parameters measured by one or more measurement and/or calculation devices of the above-specified types.

(44) The retention devices may be of shapes other than the above-described valve member 30. FIGS. 3A, 3B, 4A to 4C, and 5A, 5B show a few variants.

(45) FIGS. 3A and 3B show the bottom end of a concreting column 12 of the above-described type.

(46) As in the above example, the bottom end of the column 12 presents an outlet orifice 18 that opens out axially.

(47) In this example, the retention device is formed by a tube 40 that is coaxial with the concreting column 12, being mounted inside said column 12, and that is movable in translation along the axial direction A, specifically by actuating an actuator 20.

(48) The tube 40 presents an axial length that is substantially shorter than the total length of the column (i.e. its maximum length), and in particular a length that is no more than 20%, and preferably no more than 5%, or more preferably no more than 2% of the total length of the column.

(49) It is closed at its axial end furthest from the top end of the column 12, and it is opened at its opposite end. When it is fully inserted inside the column, as shown in FIG. 3A, the tube 40 totally closes the outlet orifice 18 of the column.

(50) A lateral opening 42 is formed in the side wall of the tube 40. The opening 42 is arranged in such a manner that an axial movement of the tube 40 away from the column 12 serves to uncover the opening 42, at least in part, as shown in FIG. 3B and serves to allow concrete and/or mud leaving through the orifice 18 to pass to the outside of the column 12.

(51) In a second variant shown in FIGS. 4A to 4C, the retention means are similar in shape to the preceding variant, but the concreting column 12 now has an outlet opening 19 formed in its side wall.

(52) In this example, the valve-forming tube 40 is adapted to be moved axially relative to the column 12, specifically by means of an actuator 20, so that the axial openings of the tube and of the column, given respective references 42 and 19, are positioned facing each other in at least one configuration of the installation as shown in FIG. 1C, and so that the flow section through the axial opening 19 of the column 12 can be modified by moving the tube 40 relative to the column 12.

(53) In the position shown in FIGS. 4A and 4B, the lateral opening 19 of the column 12 is shut by the side wall of the tube 40. The flow section through the lateral outlet opening 19 is zero.

(54) In contrast, in the position shown in FIG. 4C, the lateral opening 19 of the column 12 faces the lateral opening 42 in the tube 40. Concrete and/or mud contained in the column 12 can escape therethrough via said openings 19, 42.

(55) In the variant shown in FIGS. 5A and 5B, the retention device is formed by a tube 40 that is coaxial with the column 12, but this time mounted on its outside. As in the preceding variant, the concreting column 12 has a lateral opening 19 and the tube 40 has a lateral opening 42. In this example, the tube 40 is mounted to be movable in turning about the axis A.

(56) On being moved relative to the column 12, the tube 40 can go from a position as shown in FIG. 5A in which the lateral opening 42 and 19 of the tube 40 and of the column 12 face each other, allowing concrete and/or mud to pass, to a position as shown in FIG. 5B, in which the openings 42 and 19 overlap not at all or in part only, thereby defining a flow section that is smaller than in the preceding position, and possibly a flow section that is zero.

(57) FIGS. 6A and 6B show a concreting installation 110 in a second embodiment of the invention.

(58) As in the above embodiment, the concreting installation 110 has a concreting column 112 of axis A, through which concrete is inserted into the excavation E.

(59) It may also have a support structure, support and guide means for concreting column, and other items of equipment as described with reference to the first embodiment. The characteristics described with reference to FIG. 1 are not repeated at this point for reasons of concision, but they remain applicable to this second embodiment.

(60) The concreting column 112 has a concrete retention device in its top portion.

(61) In the example, the retention device is constituted by a valve 160, in particular a sleeve valve, well known to the person skilled in the art.

(62) Specifically, the valve 160 forms an intermediate level for retaining the concrete.

(63) With reference to the example of FIG. 6A, the column 112 presents a total height H2. A valve 160 is placed at a distance H5 from the top end of the column 112, where the distance H5 is less than half the total height H2 of the column.

(64) During priming, the valve 160 is partially closed, so as to avoid concrete descending abruptly in the mud-filled column, and in order to avoid the above-mentioned segregation and plug phenomena.

(65) In order to control the descent of the first concrete into the mud when starting concreting, the installation has a device for measuring the flow rate inside the concreting column 112.

(66) In this example, the measurement device includes a height 152 connected to the concreting column in the vicinity of its bottom end and fitted with a flow meter 154, itself connected to the control unit 90.

(67) As shown in FIG. 6A, during the initial stage of concreting (priming), the concreting column 112 is plugged at its bottom end (the bottom end of the column 112 presses against the bottom of the excavation). The mud, pushed by the concrete, is discharged by the pipe 152.

(68) By measuring the flow rate of mud in the pipe 152 by using the flow meter, it is possible to determine how the concrete has advanced inside the column 112. It is thus possible to determine the moment when the column 112 is full of concrete.

(69) At that instant, the column 112 can be moved so that its bottom end is spaced apart from the bottom of the excavation E. The valve 160 is opened. A plug, possibly shutting the bottom end of the column, is disengaged by the weight of concrete, and the excavation is concreted at a controlled flow rate.

(70) As in the above-described embodiment, after concrete has filled a predetermined volume of the excavation, the feed of concrete to the column is stopped, the column is raised through a height substantially equal to the length of a segment, and the top end element is removed.

(71) When concreting is restarted, the valve 160 is put into the closed position, so that the concrete poured into the column is retained at the level of the valve 160. The concrete drop height is equal to the distance H5 minus the length of a column element, and it is selected not to exceed the limit drop height of concrete.

(72) In this state shown in FIG. 6B, an air-filled empty space 170 is defined between the valve 160 and the bottom end of the column, and more precisely between the valve 160 and the free surface of the concrete that remains in the bottom portion of the column at the end of the last concreting cycle.

(73) The valve is then opened, in part or in full, in order to continue concreting. The drop height H6 of the concrete inside the empty space 170 once more does not exceed the predefined limit.

(74) When concreting is restarted, with the valve 160 being opened, the air situated downstream from the valve can be held captive in the concrete at high pressure. In order to avoid any risk of the concrete being expelled from the top end of the column, the concreting installation has means for evacuating the air held captive in a segment of column.

(75) By way of example, the excavation means comprise an air pipe 150 arranged outside the column and communicating with the segment of the concreting column 112 that is situated directly downstream from the valve 160.

(76) As shown in FIG. 7, the pipe 150 may also extend axially inside the concreting column. Under such circumstances, it may be movable and may include a flow meter 154 for measuring the flow rate of mud inside the concreting column at the time of priming. It thus performs the function of the above-described pipe 152, which can thus be omitted.

(77) FIG. 8 shows a third embodiment of the invention, in which retention devices are arranged to act during a single concreting cycle to retain concrete at the level of a plurality of retention points that are axially spaced apart inside the concreting column.

(78) For this purpose, a plurality of valves 260a, . . . , 260d forming retention devices and actuated independently of one another are distributed along the height of the concreting column 212, each valve forming such a retention point, or in other words a level for retaining concrete.

(79) FIG. 8 shows the concreting installation before beginning a second concreting cycle.

(80) The furthest upstream valve 260a (i.e. the valve closest to the top end of the column) is in the closed position.

(81) Concrete V, poured into the column, is retained at this valve 260a.

(82) If the valve 260b situated immediately downstream from the first valve 260a is also closed, then an air-filled empty space 170a of height H7 is defined between the two valves 260a, 260b.

(83) When the first valve 260a is opened, while the second valve remains in the closed position, the volume of concrete V drops through the height H7, that is selected to be less than the limit drop height of the concrete.

(84) The same principle is applied to the other valves 260c, 260d, etc., so as to fraction the movement of the concrete inside the column 212 into a plurality of segments of acceptable height.

(85) Although not shown, air discharge means identical to those described above can also be used in this embodiment. In particular, discharge pipes may be provided inside or outside the column and in communication with the segments of the concreting column 212 that are defined by adjacent pairs of valves.