US2979913A - Devices for casting concrete under water - Google Patents

Description

April 18, 1961 J. BOUVlER ETAL DEVICES FOR CASTING CONCRETE UNDER WATER 4 Sheets-Sheet 1 Filed Dec. 7, 1954 April 18, 1961 J. BOUVIER ETAL 2,979,913

DEVICES FOR CASTING CONCRETE UNDER WATER Filed Dec. 7, 1954 4 Sheets-Sheet 2 April 18, 1961 J. BOUVIER ET AL 2,979,913

DEVICES FOR CASTING CONCRETE UNDER WATER Filed Dec. 7, 1954 4 SheetsSheet s April 1951 J. BOUVIER ETAL 2,979,913

v DEVICES FOR CASTING CONCRETE UNDER WATER Filed Dec. 7, 1954 4 Sheets-Sheet 4 FIG. /7. FIG. /8.

TPGM E A FIG. I9.

III

DEVICES FOR CASTING CONCRETE UNDER 4 WATER Jean Bouvier, Paris, Paul Bouillot, Wimereux, and

Jacques Bourgouin, Boulogne-sur-Mer, France, assignors to Socit Anonyme dite: Enterprise Fougerolle pour Travanx Publics, Paris, France 1 Filed Dec. 7, 1954, Ser. No. 473,574 Claims priority, application France Dec. 14, 1953 6 Claims. (CI. 61-63) It is the essential object of this invention to provide a combination of devices for casting concrete under water, which are adapted to ensure at any moment during the concrete-casting operation a strictly continuous and stable flow, thereby avoiding for all practical purposes any risk of washing out the concrete. This invention aims at achieving all the requirements characterizing a perfect concrete-casting operation of this type, i.e.:

Firstly, a correct priming of the spout must be elfected immediately upon starting the concrete casting, i.e. substituting a homogeneous concrete column for the water column initially contained in the spout;

Secondly, it is essential to obtain a regular formation of a certain mass of concrete, generally called root which, while maintaining its homogeneousness, surrounds the lower portion of the spout up to a progressively increasing height; and

Thirdly, this root must be allowed to develop itself regularly and continuously by allowing the spout to penetrate into the mass of concrete up to a substantially constant height, until the root occupies either singly or together with roots from other spouts the whole of the volume to be filled with concrete;

Fourthly, achieving the above-listed steps with a continuous rate of flow, i.e. without interrupting the concrete casting operation;

Fifthly, ensuring an automatic regulation of the concrete output during the root formation and development,

thereby making the operation 'a fool-proof one and eliminating any risk of faulty operation likely to be detrimental to the quality of the concrete.

The first feature concerning both crete Works consists in providing the bottom of the lowermost section of each telescopic portion with means such as loopholes, scallops, notches, indentations, ports, etc., enablingthe concrete to fiow laterally, so that in combination with an adequate priming plug a variable-flowshutter will be obtained which is controlled to vary the crosssectional area of the lateral orifices by either lowering the plug or raising the spout; with this assembly both spout priming and root formation can take place in an absolutely safe manner, this assembly ensures ina reliable manner the priming of the concrete casting and the-root formation due to the gradual and adjustable formation of casting orifices the smallest section of which is such as to permit the passage of the largest aggregate component.

For this purpose, the priming-plug-which is provided with adequate sealing and guiding means to avoid any jamming thereofis mounted above the stationar'yportion of the spout and suspended at a suitably selected point from the rope of an auxiliary winch provided for I actuating the plug.

As the spout is filled with a convenient volume of concrete, the plug is lowered progressively until it reaches the bottom of the lowermost section, so that at the end of its stroke both plug and spout rest on the bottom.

During thelast portion of the plug travel the concrete te States Patent O large and small con casting begins through those portions of the aforesaid lateral through orifices uncovered between the lower edge of the spout and the plug.

As the root builds up, the cross-sectional area offered 5 by these lateral orifice means is increased by progressively raising the telescopic spout, the plug remaining at the bottom end of the spout.

The extent to which the stationary portions of each spout penetrates into the corresponding telescopic portion is such that the sections constituting this telescopic portion may be removed successively as it rises, by removing laterally the trough-shaped shells of each section without affecting the continuity and fluid-tightness of the spout, and therefore without interfering whatsoever with the rate of concrete feed and/ or flow in this spout.

For rendering the root formation automatic and therefore protecting it from any faulty operation the movable spout portion may be raised by means of a ram of which the stroke is consistent with the maximum desired stroke for operating the spout as an obturator, notably at the outset, to prevent the plug from escaping. The aforesaid ram is secured to that end of the spout-hoisting rope which is opposed to the rope end anchored on the control .winch, and it is controlled from :one or a plurality of immersed photoelectric cells disposed at convenient heights along the spout Wall and adapted to control the concrete level.

This automatic device is adapted to control not only the root formation but also the regularity of the casting 30 until the latter is completed.

To accelerate the root formation the bottom end 'of the spoutmay be engaged into a positioning hole formed in the bottom or floor of the volume to be filled with concrete.

35 When unfavorable local conditions are encountered, another feature of this invention consists in providing through artificial means the operating conditions secured by the aforesaid positioning hole by disposing around the bottom end of the spout an annular member, preferably of concrete, with or without bottom wall and having an internal shape suitable for this purpose and an external form designed to avoid dissociating the concrete as the latter covers this annular member.

It is another 'object of this invention to provide a retaining device at the bottom end of the casting spout (telescopic or stationary, according to circumstances) so that the priming plug may be removed together with the spout on completion of the casting operation.

This result may be achieved due to the specific feature that the said lateral flow orifices consist of ports of a height substantially greater than that required so as to uncover a sufficient concrete-flow cross-sectional area in spite of the fact that the plug is kept to the bottom of the spout.

This increase in the height of the lateral flow orifices of the spout is necessary to secure a regular and slow out flow of the first castings from which the concrete root is formed at the bottom of the spout, thereby enabling a subsequent steady operation to be obtained With a continuous feed, without dilution nor ingress of water into the spout; proportionately, the smaller the spout diameter, the greater this increase in height of the lateral flow orifices. I

To reduce this height to a minimum, it has proved necessary to design these orifices or ports w-ithproportions adapted to open or free the perpiheral surface of the spout bottom as much as consistent with strengthrequirements. However, the height will remain such that, ac-v cording to the devices of this invention which have already been broadly disclosed, two major inconveniences occur.

The first inconveniencelies in the fact that, in travelling past the ports, the priming plug is guided only by extremely thin portions of the peripheral surface of the spout so that the plug is most likely to jam therein. This can be avoided by centering the plug by means of ribs of adequate shape which offer the minimum resistance to the concrete flow and are rigid with the plug through an axial tubular member of a length so calculated that when the plug is in its lowermost position the aforesaid ribs are still above the ports.

Accessorily, this tubular member may receive the plug descending rope so that its fixation point will be located within the plug and the assembly will not interfere with the concrete casting operation.

Another inconvenience is that if relatively high ports are provided the downward travel of the plug, as the latter uncovers the ports, will cause the concrete to flow externally of the spout at a height which is not negligible at the outset, so that a certain dilution may occur, at least with respect to a small amount of concrete. To avoid this inconvenience, it is preferable on the one hand to enable the priming plug to reach its lowermost position without producing any concrete flow, and on the other hand to provide means whereby the ports may be opened progressively in the upward direction. For this purpose, the lower portion of the spout is completed by a sliding sleeve controlled either manually or automatically by a device similar to that provided for raising the spouts, so that the outflow ports may be opened or closed completely, progressively or not.

This sliding sleeve may be mounted either internally or externally of the spout.

Accessorily, the combination of these improvements makes it possible at any time and particularly on completion of a casting operation to stop the outflow of concrete when a certain quantity of concrete is still present in the spout.

Finally, any underwater concrete casting within an enclosure or into forms implies a certain fluid-tightness of the latter. Many and different devices are known for ensuring the vertical or oblique fluid-tightness, as well as the horizontal tightness between the component elements of the enclosure or forms.

When the enclosure or forms cannot be inserted or sealed in the floor the fluid-tightness of the lower face constitutes a problem which is usually solved by resorting to the assistance of divers.

One specific improvement offered by this invention consists in forming in the lower and external portionof the form one or more box-shaped elements relatively shallow and rigid with the form, and subsequently pouring therein, by means of pipes or other suitable devices, materials of such compositions that when they take their angle of repose above the lower plane of the form they fill up the irregular cavities of the floor and produce a sealing layer sufiicient to prevent the concrete cast underwater from leaking out from the bottom of the form.

These materials may be the same as those (erg. stone bedding, gravel, sand, etc.) usually employed for lining the bottom surface of a natural soil for equalizing the latter, in many applications.

The accompanying drawings forming part of this specification illustrate diagrammatically, by way of example, a typical installation for carrying out the invention which is described hereafter. In the drawings:

Figure l is a side view partially in section of, and

Figure 2 is an elevational view, and

Figure 3 is a plan view of a platform structure for easting large concrete works.

Figure 4 is an elevational View, and

Figure 5 is a plan view of a stationary spout with feed funnel.

Figures 6, 7 and 8 are elevational, plan and sectional detail views, respectively, showing the construction of a telescopic spout section.

Figure 9 is a diagrammatical exploded view showing the lateral removal of the trough-shaped shells constituting a telescopic spout section.

Figs. 10, 11 and 12 are diagrammatic plan and front elevational and side elevational views respectively showing the lifting gears.

Figure 13 is a horizontal section of a spout hoisting device.

Figure 14 is a sectional view showing a priming plug.

Figure 15 is an elevational view showing the mounting of a priming plug in a spout.

Figure 16 shows more in detail the lower portion of a telescopic spout.

Figure 17 is a vertical section of the lower portion of a spout.

Figure 18 is an elevational view of a spout head for low-height operation.

Figure 19 is a vertical, diagrammatical view of a device for ensuring the water-tightness of the form bottom.

The installation comprises (Fig. l) a casting spout or tremie tube consisting of a vertical duct a connected to the bottom of a hopper or funnel b.

During the casting operation, the concrete level c in the hopper b ranges necessarily between two values, of which 'Ihe first value d corresponds to the uppermost level or maximum capacity of the hopper or reservoir, and The other value 9 is the level at which the water head H weighing on the previously cast mass of concrete is compensated by the column of concrete of height it within the spout and above the general level of this mass; if 8 is the density of the concrete being cast, this relation may be expressed as follows:

The most stable rate is that corresponding to the hydrostatic balance of the water, taken separately, as any concrete level c in the hopper which is lower than that of the external water surface is likely, under certain conditions, to move the water in a direction opposite to that corresponding to the concrete casting, and consequently to dilute or decompose the concrete.

The assembly shown in Figs. 2 and 3 by way of example and designed for casting relatively large concrete works is mounted on a platform 28 adapted to roll over one portion of the works which is intended for this purpose. ln the specific case of a work involving the casting of concrete between two sheet-steel pile curtains 26, 2.7, the platform may travel for example on runways or rails 31 secured on top of the pile curtains, as shown.

This platform may consist of metal structural elements and comprise notably two essential members, i.e. a working floor 1 and an auxiliary floor 2.

The dimensions of this platform are a function of the works requirements and also of the conditions in which the work is to be accomplished. Thus, if the work is to be carried out in a tidal port the platform height may be calculated to constantly keep the floors above high water, thereby permitting a continuous concrete-casting operation.

On this floor are mounted one or more spouts, their number depending on the dimensions of the work contemplated. Each spout consists of a stationary portion 4 comprising a feed funnel 3, and of a telescopic portion 33 made of detachable interfitting sections and parts. Each spout is equipped with a separate winch 6 adapted to raise the telescopic portion as the concrete level rises.

Finally, the platform is equipped with all the necessary implements, such as guard-rails, access ladders, etc.

The stationary spout 4 (see Figs. 4 and 5) comprises firstly a feed funnel 3 of cylindrical or parallelepipedic form, connected to the spout proper.

The fluid-tight connection between this stationary spout and the movable or telescopic portion is secured by providing the former at its bottom end with a joint consisting of a rubber or like ring member 8 retained beawasis tween a pair of shoulders or collars 9. Besides, a vent pipe 10, consisting of a piece of tubing welded at spaced intervals along the inner wall of the spout, is provided for venting the air when necessary.

The movable or telescopic portion of the spout assembly (see Figs. 6, 7 and 8) consists of sections intercom nected by means of flanges. Each section is made of a pair of symmetrical trough-shaped shells connected diametrally along opposing longitudinal edges to form a hollow cylindrically shaped section.

The closing and fluid-tightness may be ensured for example by means of a pair of T-section members 11 having a rubber lining 12 riveted thereon, as shown; flatiron ferrules 13 arewelded on the T- section irons 11 and provided with welded gussets or ribs 14 for stiffening and reinforcing the resulting ring-shaped member normally to the clamping places. The parts are assembled and clamped by means of bolts or keys 15. To improve the fluid-tightness the joints may be displaced angularly from one another, for example by 90 between adjacent joints.

The diameters of the telescopic spout sections are such that the ring-shaped rubber joint 8 of the stationary portion has a more or less sliding fit in the telescopic portion. 7

Moreover, the lengths of the telescopic spout sections are calculated to enable these sections to ,be dismantled (Fig. 9) as the concrete level rises, without discontinuing the casting. For this purpose, the stationary spout 4 being held against movement, the following spout section is split into its two halves and removed as it attains the level of the funnel 3, whilst the next spout 7 continues its upward movement. The purpose of the lower or auxiliary floor 2 of the platform is to permit the dismantling of the telescopic spout sections. As the telescopic spout sections are progressively moved upwards, concrete is poured continuously into the funnel 3 and care is taken that the concrete in the spouts maintains its steady flow level, for example as shown at 34, Fig. 2, below the water level.

From the foregoing it is apparent that continuousoperating conditions may be maintained without discontinuing the concrete casting'in the spouts even during the upward movement of the latter as the thickness of the concrete layer increases underwater.

Under these conditions, no clogging of the spouts can take place, contrarily to what isobserved in former installations; on the other hand, no water circulates through the layer being formed, due notably to the progressive and smooth upward travel of the spouts, and also to the regularity of the concrete feed.

Finally, for a predetermined length, the end portion of each spout is not detachable and no flanges are formed thereon. It is this end portion that remains immersed in the concrete during the concrete casting operation.

A winch 95 (see Figs. to 13), for example of the pneumatically actuated type, is provided for raising each spout. A set of pulleys 16 attached to the frame structure of the upper floor 1 enables the winch rope to pass over other pulleys 17 attached on the end section of the spout before being anchored to a stationary fixation points 18.

For priming each spout, the required fluid-tightness is ensured by means of a plug for example of the type illustrated in Fig. 14. This plug consists of a cylindrical wooden member 19 through which extends a screw rod 20. This rod is locked in position by a nut 21 and provided at its opposite end with an eye 22 for anchoring a retaining rope 25 of relatively small diameter; the fluid-tightness of this device is ensured to a sufficient degree by a rubber packing 23-, the outer peripheral edge of which projects slightly from the wooden member. moreover, the upper portion of the plug is provided with guide means 37 intended to facilitate the centering of the plug in the telescopic tube and avoiding any jamming during the operation of the device.

The plug is inserted at 24 into a spout to be primed, as' shown in Fig. 15. This plug 24 is connected through a rope 25, to an auxiliary control winch 62 and adapted to slide along the whole height of the telescopic spout assembly.

The end spout (Fig. 16) is not made up of two trough-shaped shells and has its lower edge notched, or formed with indentations or outflow ports 36, so that when the plug rests on the soil or floor the first concrete castings may flow through the gaps between the sealing plug and the lower edge of the ports 36 in the spout 35.

. With this arrangement the regular and slow flowing of the first concrete castings builds up immediately at the base of the spout a concrete root 77, thus called on account of its shape, thereby permitting a subsequent steady and continuous operation without dilution nor upward flow of water in thespout.

The root formation may be accelerated by forming it within a cavity 32 (Fig. 16) previously dug in the soil at the bottom of the spout 35. Possibly, and according to the nature and consistency of the soil, this cavity may consist of a circular cup for example of concrete immersed on the group at the bottom of the spout.

As the root is formed the spout is raised and the concrete casting accelerated by incrementing the cross-sectional area of the outflow orifices, the plug remaining centered with respect to the tube by its guiding portion 37, until it becomes possible to release it.

Other progressive concrete-distributing means than those illustrated in the form of notches, indentations or ports formed in the lower edge of the bottom spout may be provided, for example by fitting a concentrical sleeve around the lower end portion of the spout, this sleeve being also formed with ports, the assembly operating somewhat in the manner of the sleeves controlling the inlet and exhaust in valveless internal-combustion engines.

According to another feature of the invention, apneumatic ram 29 (Fig. 16) of the variable-stroke type controlled automatically from one or more photo-electric or pneumatic cells 30 may be inserted on that end of the spout-hoisting rope which is anchored to the stationary point 18. The ram-controlling cells are located on the movable spout below the water level and act as a means for controlling the concerete level in the spout; the action exerted by these cells on the ram 29 is properly determined and constitutes an automatic regulator of the concrete flow during the priming of the concrete root. With this. regulation an accurate, instantaneous action is obtained excluding any untimely control of the spout hoisting operation.

Fig. 17 shows in vertical section another embodiment of the lower portion of a spout designed more particularly for the underwater casting of relatively shallow or reinforced-concrete members, with due regard to the complementary improvements required for this specific case.

The tubular body 41 of the suspended movable spout is formed with outflow ports 42 separated by wall portions having the smallest possible peripheral length, and stiffening members 43 are provided for reinforcing the structure. The bottom end of the tube 41 is formed with an in-turned flange 44 forming an abutment for limiting the stroke of the priming plug. This plug comprises a cylindrical portion 45 capped by a conical portion facilitating the concrete flow and mounted on an axial tube 46 in which the plug-supporting ripe 25 extends, as shown, the rope being anchored to the plug by means of a suitable fixation device 47 and controlled from a winch 62 (see Fig. 16). At the upper end of tube 46 are secured at least three radial blades 49 for centering the tube 46 and, therefore, the plug 45. The fluidtightness of the plug may be improved by fitting therearound a packing 50 of suitable flexible material. The cylindrical sliding sleeve 51 illustrated herein incorporates two sealing means 52 comprising packings 53 of flexible material, clamped between a pair of screw-threaded ring nuts 54 or by means of any other adequate device.

Two or more rings 55 are provided for securing the sleeve to the ropes or levers and controlling it from the surface. Finally, the reinforcements 43 which are also intended for centering the sleeve, are formed with outturned base portions 56 to restrict the downward stroke of the sleeve.

Fig. 18 illustrates in vertical section a spout head with its device for casting underwater reinforced-concrete or plain-concrete elements of relatively moderate height.

With this equipment, the spout 33 has mounted thereover a feed hopper or tremie 58 to which it is rigidly secured. An inverted U-section iron 59 is secured laterally to the hopper 58 and to its upper portion there is attached on the one hand a suspension ring 60 hooked either to the hoisting hook 61 of a crane or to a fixed point through the medium of any suitable hoisting means, and on the other hand a winch 62 for actuating the priming plug (not shown). The position of the U-sect-ion iron 59 and that of, the winch 62 are such that the rope 63 controlling the priming plug is centered with respect to the spout 57.

Another winch 64 controlling the lower sleeve 51 of the spout is mounted on the same hopper 58 in such a position as to avoid interfering with the pouring of concrete into the hopper.

Tubes 65 may be secured by means of tie members 66 on the spout 33 (Fig. 18) for receiving vibrators (not shown).

The suspension ring 60 is so located that the thus equipped spout, when in operation, will retain its vertical position without the assistance of any external means or operator.

Figure 19 illustrates a sealing means provided at the base of the form which constitutes an improvement over conventional methods.

After proper adjustment the form 87 resists more or less uniformly on the floor 88. In the example shown a central concrete-casting spout 33 of the type described hereinabove is provided. A plurality of additional concentrical and external shallow forms such as 90, 91 are disposed around the main form 87 to constitute two or more walls 92, 93 of suitably selected materials for counteracting the natural tendency of concrete to flow or spread; these walls 92, 93 are formed from the surface, according to the known technique.

What we claim is:

1. Apparatus for casting concrete under water in a continuous manner, comprising a stationary filling hopper to receive said concrete, a stationary spout fixed to and extending downwardly from said hopper, a pipe extending downwardly from said spout and comprising a plurality of sections removably secured together in end-to-end relation, each of said sections being split along a diametral plane and comprising a pair of shells removably secured together in a fluidtight manner, the uppermost of said sections being telescopically slidable on said spout, means for raising and lowering said sections to slide them upwardly and downwardly on said spout, the length of said sections being less than the length of said spout so that when the uppermost of said sections has been slid all the way up on said spout the next adjacent section slidably engages said spout in like manner so that said uppermost section is removable by separating the shells comprising it without interrupting the flow of concrete, a plug slidably mounted in said pipe in substantially fluidtight relation, means for gradually lowering said plug, the lower edge of the lowermost section of said pipe having a notch formed therein, said plug being lowered relative to said pipe to uncover a selected and variable area of said notch to control the flow of concrete through said notch, means for sensing the level of concrete in said pipe and means responsive to said sensing means and controlling said pipe section raising and lowering means to regulate flow of concrete from said pipe as the casting proceeds and thereby maintain the concrete in said pipe at a level sufliciently higher than that of the concrete already cast to substantially balance the water pressure exerted on the cast concrete.

2. Apparatus for casting concrete under water in a continuous manner, comprising a stationary filling hopper to receive said concrete, a stationary spout fixed to and extending downwardly from said hopper, a pipe extending downwardly from said spout and comprising a plurality of sections removably secured together in endto-end relation, each of said sections being split along a diametral plane and comprising a pair of shells removably secured together in a fluid tight manner, the uppermost of said sections being telescopically slidable on said spout, means for raising and lowering said sections to slide them upwardly and downwardly on said spout, the length of said sections being less than the length of said spout so that when the uppermost of said sections has been slid all the way up on said spout the next adjacent section slidably engages said spout in like manner so that said uppermost section is removable by separating the shells comprising it without interrupting thefiow of concrete, a plug slidably mounted in said pipe in substantially fluidtight relation, means for gradually lowering said plug, the lower edge of the lowermost section of said pipe having a notch formed therein, said plug being lowerable relative to said pipe to uncover a selected and variable area of said notch to control the flow of concrete through said notch to maintain concrete in said pipe at a level suificiently higher than that of the concrete already cast to substantially balance the water pressure exerted on the cast concrete.

3. Apparatus for casting concrete under water in a continuous manner, comprising a stationary filling hopper to receive said concrete, a stationary spout fixed to and extending downwardly from said hopper, a pipe extending downwardly from said spout and comprising a plurality of sections removably secured together in end-toend relation, each of said sections being split along a diametral plane and comprising a pair of shells removably secured together in a fluidtight manner, the uppermost of said sections being telescopically slidable on said spout, means for raising and lowering said sections to slide them upwardly and downwardly on said spout, the length of said sections being less than the length of said spout so that when the uppermost of said sections has been slid all the way up on said spout the next adjacent section slidably engages said spout in like manner so that said uppermost section is removable by separating the shells comprising it without interrupting the flow of concrete, a plug slidably mounted in said pipe in substantially fluidtight relation, and means for gradually lowering said plug.

4. Apparatus for casting concrete under water in a continuous manner, comprising a stationary filling hopper to receive said concrete, a stationary spout fixed to and extending downwardly from said hopper, a pipe extending downwardly from said spout and comprising a plurality of sections removably secured together in endto-end relation, each of said sections being split along a diametral plane and comprising a pair of shells removably secured together in a fluidtight manner, the uppermost of said sections being telescopically slidable on said spout, means for raising and lowering said sections to slide them upwardly and downwardly on said spout, the length of said sections being less than the length of said spout so that when the uppermost of said sections has been slid all the way up on said spent the next adjacent section slidably engages said spout in like manner so that said uppermost section is removable by separating the shells comprising it without interrupting the flow of concrete, a plug slidably mounted in said pipe in sub- 9 stantially fluidtight relation, the lower portion of the lowermost pipe section being provided with lateral outlet apcrtures, a sliding sleeve on said lowermost section, said sleeve being slidable on said lowermost section to cover said apertures a selected variable amount to provide an outlet of variable area and means for raising and lowering said plug and said sleeve relative to said pipe and to each other to control the flow of control from said pipe and thereby maintain concrete in said pipe at a level sufliciently higher than that of concrete already cast to substantially balance the water pressure exerted on the cast concrete.

5. Apparatus for casting concrete under water in a continuous and controlled manner, comprising a filling hopper to receive said concrete, a spout fixed to and extending downwardly from said hopper, a pipe extending downwardly from said spout and telescopically slidable thereon, said pipe having in its lower end portion a plurality of lateral outlet apertures, a plug slidable in said pipe in substantially fiuidtight relation and movable downwardly to a position in which the upper surface of said plug is below at least the upper portions of said apertures so as to uncover said apertures, a sliding sleeve on the lower portion of said pipe, said sleeve being slidable on the pipe to cover said apertures a selected variable amount to provide an outlet port the smallest passage area of which is greater than the largest aggregate component of the concrete to be cast, means for detecting the concrete level in said spout, and other means responsive to said control means for moving said pipe, plug and sleeve axially relative to each other to uncover se-,

lected areas of said apertures to control the flow of concrete from said pipe and thereby maintain concrete in said pipe at a level sufficiently higher than that of concrete already cast to substantially balance the water pressure exertedon the cast concrete.

6. Apparatus for casting concrete under water in a continuous and controlled manner, comprising a filling hopper to receive said concrete, a spout fixed to and extending downwardly from said hopper, a pipe extending downwardly from said spout and telescopically slidable thereon, said pipe having in its lower end portion at least one laterally opening port extending upwardly from the lowermost edge portion of the pipe for the passage of concrete therethrough, a plug slidable in said pipe in substantially fluid tight relation, means for displacing said plug in the lower end of said pipe to vary the "opening of said port from the smallest open passage area that will allow the passage of the largest concrete aggregate to the largest open passage area in which substantially the entire area of said port is open, means for detecting the concrete level in said pipe and spout, and means responsive to said detecting means for controlling said displacement means to regulate the opening of said port and thus the flow of concrete therethrough to maintain the concrete level in said pipe sufiicient to ensure that said flow is continuous and regular against water pressure.

References Cited in the file of this patent UNITED STATES PATENTS 676,568 Mouchel June 18, 1901 1,093,745 Turner Apr. 21, 1914 1,164,600 Forster Dec. 14, 1915 1,256,074 Taft Feb. 12, 1918 1,389,007 Norbye Aug. 30, '1921 2,003,393 Satre June 4, 1935 2,046,120 Harrington June 30, 1936 2,555,359 Montague June 5, 1951 2,664,910 Boyd et al. Jan. 5, 1954 2,780,920 Silvert Feb. 12, 1957 FOREIGN PATENTS 501,636 France 1920

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