US1360767A - Wall resisting thrust of earth and water - Google Patents

Description

E. LACAZE.

WALL RESISTING THRUST 0F EARTH AND WATER.

APPLICATION FILED JUNE 12, 1919.

1,360,767. Patented Nov. 30, 1920.

HTTO/IWA'YS UNlTED STATES PATENT OFFICE.

EnUARnoLacAzE, or BUENOS AIRES, ARGENTINA.

\VALL RESISTING THRUST OF EARTH. AND WATER.

crials inthe construction of walls designed to generally resist by their own weight the horizontal thrust of the earth and of the water, a method has been adopted according to which suchwalls are erected by casting shaped walls of pure or reinforced concrete, in which the weight of the filling serves to substitute the weight lacking in the wall for assuring. the stability of the same.

In accordance with the invention hereinafter to be described, provision is made for using the weight of the phreatic water for obtaining the stability of walls. This method allows at the same time of the ellicient and sure drainage of such structures, that is, the elimination of the horizontal thrust of the water which would act on the wall in case the level of the water in front of the same should descend to a level below that of the phreatic water to the rear of the wall, a phenomenon which frequently occurs in connection with the walls of sluices, high water docks open to rivers, moles, etc.

In other words, by the novel system of walls with drainage, the same favorable conditions of stability are secured for a high level as well as for a low level of water in front of the wall, thereby rendering unnecessary the reinforcement heretofore required for the purpose of stabilizing the wall, even in .the extreme event of a maximum rise of the phreatic water coincident with a maximum descent of the free water. The wall profile stable for high water, levels will in all cases also be stable Without any reinforcement for low water levels.

The force which I utilize in order to attain the above favorable results, is the atmospheric pressure which is adapted to balance a water column of a height of up to about 10 m. Without determining the shape of the wall, the material to be employed in its construction or the method of erecting the same, the utilization of atmospheric pressure requlres the consideration of the Specification of Letters Patent. P t nted Nov. 30, 1920.

Application filed June 12, 1919.

Serial No. 303,570.

at least at its upper end or top and laterally, with its upper thread below the level of the phreatic water. This hollow space within the wall, whose walls are to be watertight, is filled with water owing to its position within the phreatic water. This water remains within the hollow space owing to the lack of drainage and because the air is prevented from gaining access thereto, even if the free water in front of the wall should descend to a level lower than that of the phreatic water.

2. Separated from this hollow space, by means of any suitable watertight structure, such as intermediate divisions, etc., are sections or compartments provided with an inlet pipe for the air and another pipe for draining the water, so that such separate hollow spaces may drain according to the position of the drainage pipe and the accidental level of the free water of the dock, river or the like.

In case no restrictions are imposed by the method of construction of the wall, etc., the lateral walls of the hollow space should conveniently extend as far as the lowest possible level to be reached by the free water. The drainage pipe will also be arranged below that level.

The hollow space which extends through the whole length of the wall, is impervious to air, not only on account of its watertight construction but also because said space is submerged within the phreatic water which perfectly isolates the same from the air.

The water contained within the separate and ventilated sections or compartments is exhausted, whereby a depression of the level of the water is produced, in accordance with the position of the drainage pipe and the low tide in front of the wall. The remainder of the hollow space in the wall will hold its contents of water which will now only be under the pressure of the depressed level of the separate compartments and no more under the pressure of the level of the phreatic water. In consequence, the difference of pressure between the phreatic water and that of the drained compartments, will allow of part of the phreatic water filtering through the filling and entering into the general hollow space below the wall, filled with water, but at a lower pressure than that of the phreatic water, according to the reduced level of the water in the interposed sections or compartments. The said incoming phreatic water will partially displace the water contained within the hollow-space which thereupon enters into the sectlons or compartments provided with draining means by which it may freely issuetoward the dock, river, etc.

For the above reason, the dimensions and number of draining outlets are to be selected in accordance with the-amount of the water entering by infiltration, as above set forth, in orderto assure in all cases the depression ofthe level in the separate hollow space as the'level of the free water in front of the wall descends.

"Forthelpurpose of assuring at any event the workin'gof the drainage, suit-able meansor devices may be provided for'exactly measuring the depress on.

The depression of the water in the sep 'aratesectio'ns or compartments thus having the action of the atmospheric pressure.

' The effect of this system of wall with drainage as regards stability, is as follows: 1. As the free water descends and the horizontal thrust of the phreatic water increases, the weight of the wall owing. to the weight ofjthe-body of water retained therein,will increase, by the action of the drainage and by the heavier specific weight of the earth which rests on the'wall, owing to the elimination of the sub-pressure.

2.,De'crease [and even elimination of the increase of thrust of the phreatic water on the wall is secured, owing to the descent of the free water in front of thewall to a level lower than that of the phreatic water behind the same.

For the clearer understanding of this specification, illustrative drawings have been annexed thereto, in which:

Figure 1 is a diagrammatic representation:of the construction of the conjoint of a wall with its drainage means, not limited however to any particular profile or construction, etc.

ticular profile selected for the wall, is established, inorder to assure the-common action of the whole drainage system. The separate compartmentbr section, ind1cated at A, is formed 1n the present case (by way of example), by a cylinder of reinforced conwater from unfavorably acting on its level,

tide, medium tide and ebb tide. K indicates the normal level of the phreatic water. The different levels shown in Fig. 2 indicate the alues for the increase. of the overload and decrease of the thrust of the water for the same wall, with or without drainage.

As Ihave already extensively set forth in the specification annexed to this application for Letters Patent, in the profile of the wall a water and air-tight hollow space is provided, of whichthe upper coping stone or plate is situated below the level of the phreatic water. This hollow space closed at all sides with exception of its lower face is in no connection with the outer open air nor with the Water in front of the wall, but only communicates by its lower open side with the phreatic water behind the wall. in the drawings, in Fig. 1 (horizontal section) the hollow space'is marked by the letters c g h and in Fig. 2 (vertical section), by the letters a b 0 d. Inthis hollowspace, a certain number of separate compartments are formed, shown in the drawings as being formed of the cylinders A, constructed of watertight materials, in a number to be determined by special reasons. These C Vlll1. ders A communicate with the outer air by means of the pipe C and commune-ate also,

by means of the pipe B, with the free water in front of the wall, or, in other words, only the special sections or compartments formed by the watertight cylinders A are provided with inlets for the air and outlets for the water, contrarily to what happens with the general void or hollow space a b 0 (Z below the wall. Owing to the possibility of the entrance of air, the water of the cylinders A may drain away as the water in front of the wall descends and as the contents of the cylinders A are very small, the level of the water within the same will always coincide with the levelof the freedescending water. The cylinder A, open at-its lower side, communicates with the hollow space a b 0 (Z and through this latter, with the phreatic water behind the wall, so that there is a possibility for part of the phreatic tater draining llb away through the hollow space a b c d by the pipe B into thewaterin front of the wall. V

.The equilibrium of the water below the wall within the void space a b 0 d is de stroycd by the drainage of the cylinders, a difference of level being formed between the water contained within the cylinders A and the phreatic water. The water from the void space cannot drain for want of entrance of air and only can be substituted by the water which under the higher pressure of the phreatic water will enter into the void or hollow space as an equal amount or water is draining away by the cylinder A and the pipe B. As suitable means are provided for allowing of the entrance of the phreatic water into'the void space below the wall, such water drains away by the cy linders A whenever the level of the water in V 7 front of the 'wall is lower than thelevel of the'phreatic water. V

According to some constructions already carried out, to the rear of the wall and along its entire extension a drainage for collecting the water filtered in from the phreatic water and for facilitating its entrance into the hollow space below the wall and its discharge through the cylindersaA is provided. Said compartments or cylinders with outlet ducts B should be provided in such number and of such dimensions that the phreatic water fil tered in through the drainages, may be discharged without loss of pressure that is to say, the level of the water within the cylinder and that of the water in front of the wall will practically always be the same during low tide.

In a manner analogous to the method of depression of the phreatic water by means of multiple wells, during low tide a transitory depression of the level of the phreatic water to the rear of the wall takes'place, practically reaching the level of the depression measured within the cylinder, which at turn coincides with the level of the free tide water, omission being made of the small difference, of pressure required for producing the speed for the passage of the infiltrating water through the void space a b c d, the cylinder A and the discharge pipe B. The number and dimensions of the draining ducts'will be of suflicient amplitude in order that the degree of pressure shall be very reduceth so that. practically, the depression of the level of the phreatic water will occur simultaneously with low tide in front of the wall, thatis to say the thrust of the phreatic water against the wall in the case of low tides in front of the same, will automatically be eliminated. Considering the foregoing explanations. it follows that as regards the stability of the wall, the phreatic water infiltrates by the draining ducts provided in the hollow space a b 0 (Z and is discharged by the cylinder A and the pipe Bywhile the water a I) 0 (Z cannot be discharged being retained within said space owing to lack of entrance of .air. As the level of the water within the cylinder A descends, an analogous depression of the level of the phreatic water occurs immediately behind the wall. Owing to this fact, the action of the phreatic water on the wall which normally exerts pressure on the same when the free water in front of the wall descends to a level lower than that of the said phreatic water, is thus eliminated.

The immediate drainage of the infiltrated water will be obtained by roviding a suitable number of cylinders It 7 Without the provision of the cylinder A, that is to say, by causing the hollow space or void (4 Z) 0 (Z to communicate with the water in front of the wall only by means of the pipe B, all the water of-the void a b 0 cl would be discharged simultaneously with the infiltrated phreatic Water, as happened in connection with all the walls provided with the normal drainage systems used up to this date. By the interposition of the cylinder A, the amount of water to be drained is practically reduced to the amount of in filtrated phreatic water not taking into account the reduced contents of the cylinders themselves which are also drained. The condition for the retention of the water in the void a, 7.10 (l, consists in absolutely preventing any entrance of air. Owing to this reason, the cylinder must attain a greaterdepth than the pipe B which by the depth of its position determines the lowest water level which may occur within the cylinder A and of the consequent local depression in the phreatic water along the wall. The head of water remaining within the cylinder A from the level of the pipe B and its lower side prevents the air from entering into a b 0 (Z by the pipe B in the case of an extraordinary low tide, lower than the level of the pipe B. 7

It has been ascertainedthat owing to the impossibility of the entrance. of air into a h 0 (Z, this void remains filled with. water although the open water in front of the wall and the phreatic water along the same should descend to a level lower than that of the phreatic water. The body of water from the depressed lcvel of the phreatic wat r and the low open or free water to the level of the tread P actuates now as a weight or charge imposed on the wall, counterbalanced by the atmospheric pressure which is adapted to counterbalance a head of water of up to 10 m.

The employment of the cylinder A allows of the drainage taking place behind the wall in the same way as in the method used before, without cylinder but with a connecting pipe B; the novel arrangement prevents phreatic water.

V at thelsametime the drainage ofthe void. a b a (Z, reducing to a minimum the move-c mcnt of water below and behind the wall. Owing to the, amount of water retained within a. be (Z, the weight of the wall is mcrea'sed during the time at which the level.

of the low tide is lower than that ofthe The increase of weight as Well as the elimination of the horizontal thrust of the water thus result in a greater lstability of the wall, obtained according to the novel drainage system to be patented.

In case there are restrictions as to the profile orv shape of the wall and of the hollow space according to the method selected for the construction thereof, it may also be convenient to use the method above described in order to partially eliminate the thrust of the water and obtain themor'ease of weight for stabilizing the wall.

Having now particularly described and ascertained the nature of my said invention and in what manner the same vis to be-perments-distributed over the length of the wall certain of said compartments being I provided with a pipe for the admission of air anda separate pipe for drainage of the phreatic and overflow-water. Y

2. A wall for resisting the thrust of eartl and water,f comprising a shell-like structure divided into a series of separate sections'or compartments over the length of the wall to form hollow spaces, said hollow spaces being designed to receive the phreatic water and overflow water against the wall above a predetermined level, certain of the compartments being placed in communication and certain of the compartments being provided with means for the admission of air and for the drainage of water therefrom.

3. The construction of walls situated within the phreatic water, characterized by the provision of a plurality of sections or compartments, a tread along the wall and having a vertical portion and an overhanging ledge, the divided walls of the compart ment being provided with openings placing the compartments in communication, a pipe for the admissionof air-to certain of the compartments and a pipe for the drainage of the water from the corresponding compartment. I

4. In the construction of walls situated within phreatic water, a wall divided into a tu're having a base, portiona-nd a top ledge,

a series of vertical walls extending at'right angles to the first named wall and forming compartments having communicating openings therethrough, a horizontal tread above saidcompartments and having a depending portion spaced from, the wall, acylinder in certain of-said compartments adjacent to the wall and having a drain pipe leading from within the same to the waterwall, and an air inlet pipe extending into the top of c the cylinder through said tread and through the wall above the high water level for the admission of air as specified,

" 6. Afwall'for resisting the thrust of earth and water comprising an inclined wall str'ucturehaving abasewportion and a top ledge, a series ofvert lcal walls-extending at right angles to the-first namedwall and forming compartments having communicating openings theretlirough, a horizontal tread above said compartments and having adepending portion spaced from the wall,- afcylinder in certain of said, compartments adjacent to the walland having a drain pipe, leadi11g from within the same to the water wall, and an air inlet pipeextending into the top of the cylinder through said treadand through the wall above the high water level, said wall being backed by earth above and below said compartments, said compartments being arranged to drain through said cylinder and pipe. leading; therefrom after the drainage of the cylinder whereby owingto the increase of the weight of the wall, a simul-' taneous reduction of the horizontal thrust will be effectedduring the change of level of the water during flood and ebb for each constellation of outer forces whereby similar static conditions are produced on each side of the wall. I

EDUARDO LACAZE.

Vitnesses A. LQBELLO,

RosnNDo ROMUR.

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