JPS6317999B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of constructing underground structures such as tunnels.

It is already known in the art to construct underground vertical walls by first providing a deep trench lined with sheet metal and then filling the trench with concrete or stone or bricks. . These trenches are commonly excavated from the surface or by open hole cutting methods.

These walls may be located in urban areas or on streets, roads,
Deep trenches are suitable for conventional known means when they must be constructed where transportation corridors such as railway tracks, airport runways, etc. are constructed and activities carried out on the surface are not to be disturbed. It can be excavated from horizontal underground passages constructed in this way and supported by support piles.

The horizontal tunnel excavated from the access shaft serves as a starting point for excavating a deep trench with the intention of constructing a vertical wall. The underpass serves as a conduit for ventilation, removal of excavated material, and delivery of columns, reinforcement, and concrete.

This known method is typically employed to construct tunnels for underground transportation systems, such as subways, through large urban centers. According to this method, the inconvenience caused by surface activities is minimized.

On the contrary, the major disadvantage of this method is that it is very expensive as it requires a considerable amount of highly skilled labor to construct the column-supported underpass.

The present invention aims to eliminate this drawback of the known methods by providing a method for constructing underground structures such as tunnels, which is obtained simply, reliably, quickly and with very little labor. shall be.

That is, the method of constructing an underground structure such as a tunnel including substantially vertical side walls according to the present invention includes the steps of horizontally driving two parallel rows of pipes into the ground separated by a predetermined distance; constructing substantially vertical walls forming side walls of said underground structure below the rows; and horizontally extending a plurality of intermediate rows of pipes into the ground between and parallel to said parallel rows of pipes. and interconnecting the parallel and intermediate rows of tubes to create a ceiling for the underground structure that is to be formed between substantially vertical walls. The step of constructing each of the walls includes the step of excavating vertical grooves from the openings provided on the lower surface of the two parallel rows of pipes, lining these grooves, and reinforcing the inside of the grooves. placing the elements and filling them with concrete or stone.

The method according to the invention therefore comprises excavating a vertical trench under an underground conduit, lining said trench with sheet metal, arranging reinforcing elements in said trench, and then filling it with concrete or stone. A method for constructing a vertical wall structure underground from an underground conduit, including the steps of forming said conduit with a pipe driven horizontally into the ground at a desired depth; Drilling of the trench can begin from a hole provided on the underside of the tube.

Thus, the labor previously required to excavate and equip a column-supported underground passage is eliminated.

Alternatively, by digging an access shaft to a desired depth from the ground surface and then sequentially pushing the pipes one by one behind the preceding pipe by a hydraulic actuator supported on the wall of the access shaft. Then, the pipe is driven horizontally into the ground through the access shaft, and as the pipe is driven, soil that enters the pipe can be taken out and carried out through the access shaft.

Furthermore, the tube sections and, for example, hydraulic actuators placed at the bottom of the access shaft and supported on the walls of the same shaft, can be inserted into the ground horizontally, one by one, behind the leading tube section. You can type in sequentially.

The invention is also capable of constructing a complete cylindrical or vaulted ceiling structure for underground tunnels of the type described above, and the same structure.

The cylindrical or vaulted ceiling is useful for constructing underground structures such as road tunnels, tunnel sections, subway stops or similar structures;
and can be used at least approximately 1.2 meters below the roadway without destroying the roadway.

Said cylindrical ceiling is of the type resting on substantially vertical side walls of masonry, in particular concrete masonry, extending along both side edges of said ceiling, said side walls advantageously extending along said side edges. This is obtained by filling deep grooves from arranged horizontal tubes, said tubes being provided with holes for this purpose on their respective undersides as described above.

A masonry cylindrical ceiling consists of a series of horizontal half-tubes arranged parallel to and at a distance from each other, each with its convex side pointing upwards and each open side pointing downwards, and the space between the tubes. It is formed of an upper bed constituted by a connecting element and a self-supporting lower bed, preferably of reinforced concrete or prestressed concrete, which is in contact with said upper bed on the one hand and the upper end of said side wall on the other hand, and said half-tube is Filled with concrete or some other stone.

According to a preferred embodiment of the invention, the connecting element between the tube halves consists of a plate providing a fluid-tight connection between the tube halves.

The half-tubes and connecting plates may be made of any suitable material, such as metal, reinforced concrete, prestressed concrete, asbestos cement, plastic, etc., but are preferably made of metal, so that the plates are particularly It can be attached to the tube by welding.

The present invention provides for constructing a masonry tube or vaulted ceiling for an underground tunnel by constructing substantially vertical side walls defining the width of said tunnel, said side walls preferably having a respective one for this purpose. A series of horizontal pipes spaced parallel to each other, obtained by filling two deep grooves from two horizontal end pipes with holes on the lower side, can be used to fill the desired height of the cylindrical ceiling. arranged so as to be distributed between said horizontal end tubes according to their shape, said arrangement being carried out by horizontally pressing the individual tube sections constituting said tubes one after the other, preferably with respective portions between said tubes. earthworks and shoring necessary to locate the connecting element substantially in the center of the height of the pipe, fill the upper half of said pipe with concrete by means of a concrete pump, and disconnect and remove the lower half of said pipe. After carrying out the work, the lower half of the tube is cut off and carried away, a frame is placed in place below the remaining depth of the upper half of the tube, and above said frame, on the one hand, the filled In contact with the upper bed formed by the upper half-tube and the connecting element, and on the other hand with the upper part of the side wall, a self-supporting lower bed of masonry, preferably reinforced concrete or prestressed concrete, is placed.

Said connecting element is a connecting plate which is provided with longitudinal slots in each or a portion of said tubes and which is then brought into said tubes and pushed through the wall of each tube between both tubes one after another until it impinges on an adjacent tube. be.

Still further, at the depth of the diametric plane substantially separating the upper and lower parts of each tube, a jamb is provided before filling of said upper part with concrete, and reinforcing elements, such as reinforcing covers, are provided in said filling of said upper part. placed in front. The framework can in particular be constituted by slabs or by prefabricated reinforced concrete slabs which are provided with reinforcing bars that protrude from their respective surfaces and can be connected to the reinforcing elements.

Said filling can advantageously be carried out for each tube by means of a rigid tube inserted into the upper part of the tube or tube section to be filled, said rigid tube being connected to said tube. It is preferably connected through a hose of the same diameter to said concrete pump, which pump delivers highly fluid concrete, while the tube to be filled is closed at both ends, said rigid tube remaining intact after filling. do.

The present invention will be better understood as the following description proceeds with reference to the accompanying drawings, which show, by way of illustration only, some embodiments of the invention, and which Other objects, features, details and advantages of the invention will become clearer.

In order that the invention and its advantages over the conventional method may be better understood, the conventional method will first be described with reference to the accompanying drawings.

In FIG. 1 of the accompanying drawings, the reference numeral 1 represents the ground surface, for example in an urban area, and the figures depicted on the right are drawn to scale as a guide.

According to the conventional method, the horizontal underground passage 2 is started from an access shaft (not shown) and then supported by supporting walls 3, 4 and 5 in a conventional manner. A deep groove 6 is excavated from the horizontal bottom of this underground passage and, as the excavation progresses, sheet metal elements 7, 8 of known types are excavated.
Lined by. The elements 7 consist of rigid plates pressed against the vertical walls of the groove and are interconnected from one wall to the other by elements 8. Of course, there is enough space for workers to pass through the underground passage 2, and all the necessary work is done, i.e. digging a deep groove 6, carrying out soil,
It is large enough to allow for carrying in and installing reinforcing elements for deep grooves, pouring concrete for deep grooves, etc.

Although this known method is reliable, it is extremely expensive, as already pointed out, due to the highly skilled work required to support the walls of the underpass.

A method and apparatus for alleviating the above-mentioned drawbacks of conventional methods in accordance with the present invention will now be described with reference to the following figures.

According to the invention, the shored underground passage 2 has:
It is replaced by a generally cylindrical tubular conduit 10 formed of prefabricated elements 11 of suitable length that are driven horizontally into the ground. For this purpose, and as in the case of shored underground passages,
An access shaft 12 is dug from the ground surface to a desired depth. A device, such as a high-powered hydraulic actuator 13, is located at the bottom of the access shaft such that it is supported at one end on the access shaft wall 14. The other end of this hydraulic actuator,
That is, at the end of the piston rod of the same machine, there is a prefabricated element,
That is, the vertical plate 1 is adapted to press against the end of the pipe section 11 to push the pipe section and drive it horizontally into the ground.
5 is provided. When the pipe section 11 has thus been completely or almost completely driven horizontally into the ground, the next pipe section 11 is lowered into the access shaft and aligned with the pipe section 11 already driven into the ground. and is subsequently pressed by the actuator 13 against and together with the leading tube section.
The underground tubular conduit 10 shown in FIG. 2 is thus obtained.

The tube section 11, which is driven horizontally into the ground, is open at both ends and is therefore filled with soil during driving. The pipe section 11 has a large diameter, for example of the order of 2 meters, and so that the soil in the tubular conduit 10 can be removed from it and finally into the shaft 1.
2 to the surface.

The tube section 11 is made of a suitably strong material capable of withstanding the stresses resulting from earth pressure and the driving forces applied by the hydraulic actuator 13 without failure. The pipe portion 11 is made of, for example, steel, reinforced concrete, prestressed concrete, asbestos cement,
It is a prefabricated element made of plastic etc.

In order to create the desired vertical walls, the tube sections are further provided with holes 16 on the underside of each, making it possible to drill deep grooves 6' lined with sheet metal. The tube section 11 is strengthened at locations weakened by said holes, for example by arches 17 of suitable material placed on each side of the holes 16. As already mentioned, the internal dimensions of the tube section 11 are determined to allow for the passage of personnel and the operations required through the hole 16, i.e. the drilling of the depth groove 6', the placement of the lining sheet metal elements 7' and 8', the depth loading and placing reinforcing elements 18 in section 6';
and large enough to allow for concreting or masonry of depth 6'.

In FIG.
The figure shows the vertical wall 19 obtained after concreting the deep groove 6'.

The method according to the invention may be applied to constructing the ceiling of an underground structure, for example an underground railway tunnel, as shown in FIG.

In FIG. 7, two strands of tubular conduit 10, each associated with a vertical wall 19, are shown in parallel relation to each other and to the tubular conduit 10, for example to form a temporary or permanent ceiling of a tunnel. It forms part of a set 20 of pipe sections 21 driven horizontally into the ground. The tubular sections 21 are connected to each other and to the tubular conduit 10, such as by a series of metal plates 22, so as to make the entire assembly a unitary structure. It will be appreciated that the tube section 21', like the tubular conduit 10, is driven horizontally into the ground, connected to the adjacent tube section 21 by a series of metal plates 22, etc., and then covered with concrete or masonry. It is filled to form the ceiling of an underground structure.

It is understood that the tubular conduit 10 in combination with the vertical wall 19 forms two parallel channels of tubular sections, and that the tubular sections 21 form lateral channels formed by the tubular conduit 10. to form mutually parallel intermediate conduits connected to.

The tube portion 11 or 21 may have a circular cross section, a polygonal cross section, or a partially circular and partially polygonal cross section.

The method and apparatus according to the invention has the following additional advantages over conventional methods: Pre-pouring of concrete into the ground to combine the conduit 10 and pipe sections 21 with vertical walls to create a totally fluid-tight assembly. Advantages that the method according to the invention reduces surface settlement and damage caused by the construction of such underground structures, the method according to the invention does not require protection by continuous pipes of steel, concrete, plastic etc This has the advantage that it is very safe for workers who can work under the ground, and that it is possible to work closer to the surface because surface settlement is reduced.

In FIG. 8, an underground tunnel 101 dug into the ground 102 is shown below the ground surface 103, which is, for example, the surface of a roadway or road pavement. This tunnel structure includes side walls 104a and 104b, a floor 1
05 and a cylindrical or vaulted ceiling 106, and these elements of the structure are preferably made of reinforced concrete or prestressed concrete. Reference numerals 107a and 107b represent the two horizontal end conduits used to excavate and fill the trenches occupied by sidewalls 104a and 104b.

The cylindrical ceiling 106 is formed by an upper bed 106a and a self-supporting lower bed 106b, the latter being connected to the upper bed 106a on the one hand and the side wall 1 on the other hand.
It is in contact with the upper ends of 04a and 104b. The upper bed 106a has a series of horizontal half-tubes 108 arranged parallel to and spaced apart from each other and oriented with each convex side upwardly and each open side downwardly directed.
115 to 115 and connecting elements 116 to 124 between the half tubes 108 to 115, said half tubes 108 to 115 being filled with concrete or other suitable masonry 125.

Reference is now made to Figures 9a-9c which illustrate the essential steps of the method of constructing the cylindrical ceiling 106.
Each of the half tubes 108 to 113 in FIG.
A series of horizontal tubes 111A and 11 shown in the figure.
Obtained as a result of cutting the lower half of 2A. These tubes are preferably arranged by any suitable means as described with reference to FIG.

Figure 9a shows two pipes 111A and 112 buried in the ground 102 during this step of the construction method.
A can be seen, and the cross-sectional dimensions of these tubes are large enough to allow workers to pass through. In the illustrated embodiment, these tubes are all metal and one
Connecting elements such as 19, 120 and 121 are also constructed from metal plates. These plates in turn provide a fluid-tight connection between adjacent tubes as seen in FIGS. 8 and 9a-9c. 120 and 121
A connecting plate such as the one shown in FIG.
6 and 127, and then the connecting plates 120 and 121 from the inside of the tubes 111A and 112A.
is the connecting plate 12 on the outer surface of the adjacent pipe, that is, inside the pipe 111A.
0 is carried in and inserted into the slot 126 from inside the tube.
slots 126 and 1 by pushing coupling plates 120 and 121 by any suitable means until they abut the outer surface of tube 112A.
27 respectively. Plates such as 120 and 121 are internally welded to metal tubes with slots inserted into which the plates are placed in place, along weld lines 128 and 129, respectively, in the case of tubes 111A and 112A.

If desired, water-tightness between successively adjacent pipes of a cylindrical ceiling can be achieved by inserting a plastic section, for example of polyvinyl chloride, between two adjacent pipes and between connecting plates which extend continuously in the longitudinal direction of each pipe. This can be ensured by

Figure 9b shows the contemplated cylindrical ceiling section after the upper half of the tube has been filled with concrete. This state is obtained from the state shown in FIG. 9a as follows. A frame 130, shown schematically, is provided to define the upper limit of each tube such as 111A and 112A, and reinforcing elements such as reinforcing bars 131 are placed, and the upper half of said tube is then filled with concrete. be done. For this purpose, a single concrete pump placed outside the structure supplies highly fluid concrete so that it can ensure filling over a sufficient length of the pipe in a single operation. A concrete pump is used. For this purpose, the pipe section whose top is to be filled with concrete is sealed at both ends and the pipe section is supplied with concrete through a tube extending over substantially the entire length of the pipe section; The tube is rigid in order to supply concrete to the tube section over the entire length of the tube section. The pipe is preferably connected to the concrete pump via a flexible conduit or hose of the same diameter as the pipe.

If it is considered that the filling of the upper part of the pipe by the equipment thus used is not sufficiently complete, then a supplementary mortar injection or grouting into the concrete filling is preferably carried out by means of a vertically arranged narrow pipe. The narrow tubes are fed with mortar through their respective lower parts opening into the lower half of the horizontal tubes. The soil below the center height of the tube has been removed and a temporary support frame, designated in its entirety by the reference numeral 132, is provided to transfer the load to the floor (first
9b), it can also be seen in FIG. 9b that said support frame has in particular an upper horizontal beam 132a and a vertical beam 132b. In precisely this situation, the connections between the horizontal pipes and connecting plates such as 119 and 120, if appropriate,
The plates abutting the outside of the tubes are reinforced by being welded along external longitudinal weld lines such as 133 and 134 in the case of connecting plates 119 and 120 abutting tubes 111A and 112A, respectively. can be done.

Figure 9c shows a later step in the method of constructing a cylindrical ceiling, during which the lower halves of the tubes such as 111A and 112A are interconnected by connecting plates such as 120 and filled with concrete 125. They have been cut and removed so that only the upper half tubes such as 111 and 112 remain in place. In this step, the support frame 135, which in particular has an upper horizontal beam 135a and a vertical beam 135b, transfers the loads applied by the false ceiling thus constructed to the floor of the tunnel.

According to a variant embodiment of the invention, earthworks and shoring are carried out by driving vertical piles at regular intervals and connecting said piles by horizontal plates (made of wood or concrete) to provide a continuous wall. This can be accomplished by using a sheet metal lining in place of the frame.

10 and/or 11, vertical side walls 104a and 104b, end horizontal pipes 107a and 1
07b, the intermediate half-tube, in this case denoted by the common reference numeral 136, and the reference numeral 137
The tunnel floor represented by can be seen. 1st
The right-hand part of Figure 0 corresponds to the situation shown in Figure 9b, but includes a support frame 132 constituted by beams such as 132a, 132b and 132c, designated by the common reference numeral 136A. It can be seen that it is placed below the complete tube shown as Next, in the tunnel section shown in the center of FIG. 10, the lower half (shown in phantom) of tube 136A has been severed and removed, now leaving the structure in place. Load is on tunnel floor 1
37 by a support frame 135 with beams 135a, 135b and 135c, this part of the tunnel corresponds to the situation shown in FIG. 9c. The tunnel section shown in the left-hand part of FIG. It shows a frame constructed by a bottom plate 138 that is supported by a base plate 138. Furthermore, the beams 150a,
A support frame 150 formed by 150b and 150c helps support concrete bed 106b.

In the embodiment shown in FIGS. 12 and 13, the entire structure of the cylindrical ceiling of the tunnel and the method of constructing the same is shown in FIGS. 8-11. The configuration is similar to that of the embodiment, but
The configuration of the embodiments of the frame in the tube is different.
Furthermore, it can be clearly seen that connecting plates such as 140, 141 and 142 are placed in place within a tube such as 146 and attached to the same tube along internal weld lines such as 140a and 141a, and of adjacent tube 147. 143, 144 and 145 placed in place from inside and welded to the same tube along internal weld lines such as 143a.
They are alternately welded with connecting plates such as.

Figure 12 shows 14 from the concrete pump.
6, 147 and 148 are seen, and a narrow vertical pipe 161 is also seen for injecting make-up mortar to complete the concrete filling of said upper part. It will be done. In this case, the framing is done by means of a bottom plate 162 as shown for end tube 146 of the cylindrical ceiling or by 163 for tube 147.
It is constructed of small prefabricated reinforced concrete slabs such as a and 163b. These slabs are constructed by longitudinal wooden beams 164 supported by columns 165, and by studs such as 167 welded to the walls of the tube in the longitudinal direction of the tube, and the portions of the connecting plates projecting into the tube. 16 worn alternately with
It is supported by a suitable device such as said section in combination with a wooden beam such as 6. On the other hand, the bottom plate 162 is supported in the center only by the beam 164, on the right hand edge by the protruding part of the connecting plate, and on the left hand edge by the longitudinal wooden beam 166a attached to the tube 146 by studs 167. It is being

Reference numeral 168 represents reinforcing elements of concrete (not shown) such as 146, 147 and 148 to be introduced into the upper part of the tube.

What will be noted is that each prefabricated reinforced concrete slab such as 163a has 1
The protruding and therefore reinforcing element 168 at 69
It is possible to be provided with reinforcing bars that can be connected to.

Of course, the configuration and construction of the free-standing lower bed will depend on the properties of the overall structure to be obtained, and the above description is only an example.

Of course, the invention is in no way limited to the form of the embodiments shown and described above, which are merely for purposes of illustration. In particular, the present invention covers all devices and techniques equivalent to the devices and techniques described above, as well as combinations thereof, if the latter are made in accordance with the subject matter of the invention and used within the scope of the appended claims. include.

[Brief explanation of the drawing]

FIG. 1 is a schematic vertical cross-sectional view of a buttressed support wall passage and sheet metal lined trench according to the conventional method; FIG. 3 is a vertical sectional view of the pipe section and deep groove according to the present invention; FIG. 4 is a vertical sectional view of the longitudinal direction corresponding to FIG. 3; and FIG. 5 is a concrete reinforcing device in the deep groove. FIG. 6 is a vertical sectional view corresponding to FIG. 3 after the concrete has been placed, FIG. 6 is a view corresponding to FIG. Vertical cross-sectional diagram of the structure, No. 8
9a-9c are cross-sectional views of an underground tunnel provided with a cylindrical or vaulted ceiling in accordance with an embodiment of one form of the present invention; FIGS. 9a-9c illustrate a method of constructing the cylindrical ceiling of FIG. A detailed partial cross-sectional view showing various steps; FIG. 10 is an axial longitudinal cross-sectional view showing the various steps of constructing the cylindrical ceiling, including the cylindrical ceiling of the entire underground tunnel shown in FIG. 8; FIG. 11 is a detailed view of the underground tunnel. FIG. 12 is a sectional view taken along line XI--XI in FIG. 10, and FIG. 12 is a sectional view taken along line XII--XII in FIG. ivy cross section,
FIG. 13 is an axial horizontal longitudinal sectional view of the same bed taken along the line - in FIG. 12. 6'..."It's deep lined with sheet metal", 7',
8'... "Sheet metal lining element", 10... "Tubular conduit", 11... "Pipe section", 16... "Hole" provided on the lower side of the pipe section, 18... "Reinforcement element", 19... "Vertical wall" .

Claims (1)

[Claims] 1. A method for constructing an underground structure such as a tunnel that includes substantially vertical side walls, comprising the steps of: driving horizontally into the ground two parallel rows of pipes spaced apart by a predetermined distance; constructing a generally vertical wall forming a sidewall of said underground structure below each row of tubes; and constructing a plurality of intermediate rows of tubes between and extending parallel to said parallel rows of tubes. and creating a ceiling for the subterranean structure that is to be formed between substantially vertical walls by interconnecting the parallel and intermediate rows of tubes. The step of constructing each of the substantially vertical walls includes the step of excavating vertical grooves from openings provided in the lower surfaces of the two parallel rows of pipes, and lining these grooves; placing reinforcing elements in the trench and filling it with concrete or stone. 2. In the method described in claim 1,
Digging from the ground surface to create two parallel rows of vertical entry and exit shafts to approximately the desired depth, and sequentially moving the pipes one by one after the preceding pipe using a hydraulic actuator that pushes the walls of the entrance and exit shafts. A method characterized by driving the soil horizontally into the ground from the access shaft by pushing, removing the soil from the pipe driven into the ground, and carrying the soil up through the access shaft. 3. A method according to claim 1 for constructing a masonry vault for an underground tunnel, comprising a series of mutually parallel spaced apart structures distributed according to the desired contour of the vault. placing connecting elements between adjacent rows of pipes, filling the upper half of said pipes with concrete by means of a concrete pump, and performing necessary earthworks and shoring. cutting and removing the lower half of the tube after carrying out the construction; providing a frame under the upper half of the tube remaining in place; A method characterized in that it comprises the step of providing a free-standing lower bed of stone in contact with the upper bed formed by the tube and said connecting element, and on the other hand in contact with the upper part of the side wall. 4. In the method described in claim 3,
A method characterized in that each connecting element consists of a connecting plate, which is inserted into the tube and pushed through a longitudinal slot in the wall of the tube until it abuts an adjacent tube. 5. In the method described in claim 4,
A method characterized in that the tubes and connecting plates are metal and that each connecting plate is welded to the tube into which it has been pushed along its longitudinal weld line before the upper half of the tube is filled. 6. In the method according to claim 4 or 5, a plastic piece is inserted between consecutive connecting plates in the longitudinal direction of a row to prevent water leakage between adjacent pipes in a row. A method characterized by forming a part. 7. In the method described in claim 4,
If the tubes and connecting plates are metal, each connecting plate is welded longitudinally on the outside of this tube to the tube it abuts after the upper half of the tube is filled and before the lower half of the tube is cut and removed. A method characterized by welding along a line. 8. In the method described in claim 3,
characterized in that, before the upper half of the tube is filled with concrete, a frame is provided approximately at the same level as the diametrical plane separating this upper half from the lower half, and that the upper half of the tube is provided with reinforcing elements before its filling. how to. 9. In the method recited in claim 8,
A method characterized in that the frame has a bottom plate supported by means fixed to the inner tube wall. 10. The method of claim 8, wherein the frame comprises a prefabricated reinforced concrete slab, which projects from the surface and is adapted to be connected to reinforcing elements in the upper half of the tube. A method characterized in that the method is characterized in that it is provided with reinforcing elements made of 11. The method according to any one of claims 3 to 10, wherein the filling of the upper half of the tube is carried out in a rigid tube inserted into the upper half of the tube containing the row to be filled. This is done for each row, and this rigid tube is connected by a flexible conduit of the same diameter to a concrete pump arranged to deliver highly fluid concrete, and when the concrete is about to be filled. A method characterized by closing the row at both ends and leaving the rigid tube intact after filling. 12. A method according to claim 11, characterized in that filling is completed by injecting finishing mortar, if necessary, through a small tube in the upper half of the tube.