US3386510A - Method of installing well points - Google Patents

Description

June 4, 1968 H. scHNABEl., JR

METHOD OF NSTALLING WELL POINTS 2 Sheets-Sheet 1 Filed Jan. 3, 1966 n mw .kil n M W L, k, my.

`lune 4, 1968 Filed Jan. 3, 1966 METHOD OF NSTALLING WELL POINTS H. SCHNABEL., JR 3,386,510

2 Sheets-Sheet 2 Harry Schnabel Jr.

A QRNEYS INVENTOR United States Patent O 3,386,510 METHOD F INSTALLING WELL POINTS Harry Schnabel, Jr., 5210 River Road, Bethesda, Md. 20616 Filed' Jan. 3, 1966, Ser. No. 518,430 12 Claims. (Cl. 16S-34) ABSTRACT 0F THE DISCLOSURE There is disclosed a -method of installing a well point system in which each well point pipe has a continuous and uniform noncircular cross section, by drilling each noncircular pipe into the ground while simultaneously jetting water through the pipe. There is positioned in closely fitting relation with the pipe strainer a sleeve, insoluble in cold water but highly soluble in hot water, which sleeve is removed by passing hot water through the well point after it has been installed.

This invention relates to an improved method for quickly and inexpensively installing well points.

Well point systems are widely used to exhaust or drain water from a selected ground area to lower the water table in the area. Such systems have found particular application in various excavation projects such as the construction of building foundations, sewers, tunnels, bridges, pumping stations and the like. The well point system is employed to keep water out of the excavation while work proceeds.

Certain problems have arisen in connection with the installation of heretofore known well point systems. Well points are generally installed by forcing the well point pipes into the ground and leaving them there. Considerable ditliculty is often experienced in installing the pipes in gravel or other hard soil. Although Imany different expedients have been devised in attempts to meet this difficulty, they have been characterized by certain undesirable features. For example, some systems employ well point pipes which can only Ibe driven through the ground and cannot be used for jetting holes to receive themselves. Other systems, perhaps in the widest usage, employ well point pipes which can be jetted into the ground but cannot be driven. Most of these systems em ploy complex and expensive valve arrangements to permit jetting through the bottom of the pipe during installation but prevent axial inflow of ground water into the end of the pipe. Still other systems employ well point pipes which can be driven and/or jetted but cannot be drilled into the ground.

One aspect of the present invention provides a very simple well point system which is capable of being installed through a simultaneous combination of jetting, driving, and drilling. In this way, the system may be effectively and economically installed in most types of soil. Heretofore known systems have employed well point pipes having a circular cross section. Thus, the pipe must be tightly gripped by a chuck or other means in a rotary table in order to apply the necessary force to rotate the pipe. It is difiicult to tightly grip the pipe in such a manner and still permit it to slide through the rotary table and be driven into the ground. Moreover, such tight gripping tends to cut or mar the surface of the pipe and create weak points. Thus a major problem in the installation of Patented June 4, 1968 ICC well point pipes has been to apply a rotative force to the pipes while simultaneously permitting them to be driven into the ground. In accordance with one aspect of this invention a noncircular, preferably square, well point is used to prevent slippage in the grip of the rotary table.

Well points conventionally have multiple perforations through the lower peripheral wall to provide a strainer inlet for ground water which inlet excludes earth, rocks and other large solid objects. During the jetting operation, these perforations permit the jetting water to emerge through the side of the pipe as well as through the bottom thereby reducing the effectiveness of the jet.

Further, during the sinking of the Well point, the perforations may be clogged. Such clogging is a particular problem where a noncircular pipe is drilled into the ground.

To overcome the disadvantages of the prior art, it is an object of the present invention to provide an improved method for effectively and economically installing well point systems.

Another object of the invention is to provide such a method capable of utilizing the simultaneous, combined actions of drilling, driving and jetting.

Still another object of the invention is to provide such a method in which the strainer openings through the wall of the well point are sealed during the installation and quickly and easily opened after installation.

In general, one aspect of the invention relates to a method of installing a well point system which comprises providing a plurality of well point pipes of uniform, noncircular cross section, said pipes having open bottoms with side openings near said bottoms, sinking said pipes to a desired depth into the ground at spaced locations by simultaneously slidingly and drivingly engaging each of the pipes in a rotary drilling table having a noncircular pipe receiving opening to receive the pipe in driving relation and rotating the rotary table, applying a downward force to each of the pipes, and jetting water downwardly through each of the pipes while it is being rotated, thereafter obstructing said open bottoms below said side openings against the admission of earth, connecting a header to each of the installed pipes, and connecting a pump to the header.

The invention also contemplates a method of installing a well point which comprises applying a sleeve in closely fitting relation with the lower portion of a well point pipe having an open bottom and strainer openings through the side of said lower portion so that said sleeve closes said openings, said sleeve being substantially insoluble in water over a normal operating temperature range and being highly soluble in water over a temperature range substantially higher than said normal range, sinking said pipe to a desired depth in the ground while jetting water downwardly through said pipe at a temperature in said normal range leaving said sleeve intact, and passing water into the thus sunk pipe at a temperature in said higher range for a time sufficient to dissolve said sleeve. While the use of the sleeve with the stated water solubility characteristics is particularly advantageous in combination with the described drilling of a noncircular pipe, such use is not necessarily so restricted.

The invention having been generally described, a preferred specific embodiment will now be set forth in detail with reference to the accompanying drawings in which:

FIGURE 1 is a perspective view of a well point system il installed according to the invention with a portion of the surrounding ground area shown in section;

FIGURE 2 is a side elevation view of a well point being installed in the ground and an apparatus for installing it;

FIGURE 3 is an enlarged top plan view of the rotary table of the apparatus of FGURE 2 showing the manner in which one of the noncircular pipes is slidingly and drivingly engaged in the corresponding pipe receiving opening of the rotary table;

FIGURE 4 is a fragmentary view, partially in section showing the bottom of a well point with a strainer sealing sleeve used during installation;

FIGURE 5 is a horizontal section taken along the line 5 5 of FlGURE 4; and

FIGURE 6 is a horizontal section corresponding to FIGURE 5 showing a modified form of sleeve.

illustrated in FIGURE l of the drawings is a well point system 11 installed in the soil 12 adjacent an excavation 13. The well point system 11 is generally comprised of a plurality of well points 14 connected by a header 15 which, in turn, is connected to a suction or vacuum pump 16.

The well points 1d may be sunk into the ground adjacent a construction project such as an excavation to a predetermined depth and remain there so as to enable the ground water to be drained in the area surrounding the excavation. The well points 14 are connected to the header 15 by intake connections 17. The suction or vacuum pump 16, which may be of any suitable type, is connected to the header 15 by intake connection 18 while the discharge side of the pump may be connected to a discharge line leading to a storage area or other suitable place of water disposal.

Although the well points 14 are shown in the drawings as all being sunk to approximately the same depth, it will be understood that they may be sunk to different depths if necessary. The well points of the system are preferably spaced from three to nine feet apart, depending upon the amount of water contained in the soil and the characteristics of the particular soil. However, the well points must not be sunk into the ground to a depth greater than the range of the pumps suction.

Each of the well points is generally comprised of a noncircular pipe having a lower Huid inlet end and an upper outlet end. Each of the pipes 20 is provided on its extreme lower inlet end with cutting teeth 21. Immediately above the cutting teeth, the lower inlet end of the pipe is provided with a screened portion having a plurality of openings 22 through the side of the pipe for the intake of water from the surrounding soil after the well point has been installed. The screen openings exclude earth and rocks, it being understood that some tine solids inevitably are admitted.

A drilling rig having mostly conventional components may be used to install the well points 14. Shown in FIG- URE 2 of the drawings is a vehicle 23 having a power driven winch 24 and a derrick or tower 2S mounted on its rear end. During installation of the well points 14, the pipe 2t) is supported at its upper end by a conventional swivel assembly 26 which permits the pipe to be rotated while still permitting water to pass therethrough. The swivel connection in turn is supported by a power-operated cable 28 wound on the winch 24. The cable 28 has one end connected to the top of the swivel 26. The cable then extends upwardly over a pulley 29 hanging from the top of the derrick 25. The cable then extends down and around the winch 2d, up over a sheave 30 in the swivel assembly and then down to an anchor 31 at the rear of the vehicle 23. Operation of the winch 24 thus applies a downward force to the pipe 20 to drive it into the ground.

Water or other drilling iluid may be supplied to the swivel assembly 26 and downwardly through the pipe 20 by a exible hose 32 leading from a water connection on the vehicle 23.

Rotative force is applied to the pipe 14 by a power driven rotary table 33. In the particular form of the rotary table shown in FIGURE 3, the power is transmitted through gears 34 and 35. Both the winch 24 and the rotary table 33 may be driven by a motor 37. The rotary table is provided with a noncircular opening 36 which corresponds in shape to and is slightly larger than the pipe 2% to receive the pipe in sliding driving relation. Preferably the opening 36 and the cross section of the pipe 2@ are square. In operation of the rotary table the pipe 2i? is loosely or slidingly received within the opening 36 so that a slidable driving engagement is effected. In this manner, a downward force may be applied to the pipe while at the same time a rotative force is applied to the pipe by the rotary table to drill the pipe into the ground to a predetermined depth. Although in the preferred embodiment the pipe 2? and the corresponding opening 36 are square in cross section, it will be understood that any suitable noncircular configuration may be employed. For example, the cross section of the pipe and the table opening may be a triangle, hexagon, or other polygon, an ellipse or other noncircular closed curve. The cooperating noncircular configuration of the pipe 29 and the opening 36 thus permits a rotative force to be applied to the pipe while simultaneously permitting it to slide through the opening as the pipe is driven and jetted into the ground.

The use of a square pipe is particularly advantageous in that the corners of the pipe, as the pipe is rotated, readily cut a hole surrounding the pipe which is larger than the pipe itself. The enlarged hole reduces the frictional resistance of the soil to the sinking of the pipe. It also permits coarse material in the soil to settle to the bottom of the hole adjacent the tip of the well point. The enlarged hole also acts as a reservoir which is convenient for collecting the water from the surrounding soil so that it may be easily exhausted by the well point system.

As previously explained each of the well points of the present invention is provided on its extreme lower inlet end with a cutting tool. After the well point has been installed in the soil, the tip of the pipe, or the portion containing the cutting tool, may be obstructed by any suitable device or material applied below the screen openings 22. The obstruction can be, but need not be, a complete seal. It is normally sufficient if earth is excluded but water is admitted as by lling the bottom of the pipe with a porous material. Alternatively even water may be excluded as by grouting concrete into the end of the pipe below the screen after the latter has been sunk to the desired depth. Thus water would be admitted only through the screen openings 22.

After all of the well points 14 are in place, the header 15 is connected to them and then the pump 16 is attached to the header.

The method of the present invention is advantageous in that it is capable of quickly and easily installing a well point system through a simultaneous combination of jetting, driving and drilling. In this way, the system may be installed in most types of soil commonly encountered. It is not necessary to tightly grip the Well point pipes in order to drill them into the ground. Thus, the pipe may easily slide through the driving means. Further, the weakening of the pipes normally occasioned by the cuts or disfigurations resulting from their being tightly gripped is avoided.

An important aspect of the invention is the use of a sealing sleeves 41 in each pipe 20 during the installation of each well point 14. The sleeve is installed in the pipe prior to the start of the sinking operation. As shown in FIGURES 4 and 5 the sleeve 41 is mounted in closely fitting frictional relation to the square pipe 20 to seal the openings 22 over the length of the screen yarea. Thus mounted the sleeve 41 will not move axially in the pipe during the pipe sinking operation.

An important Iphysical characteristic of the sleeve 41 is its water solubility properties. The sleeve may be of any of several commercially available materials having the property of being substantially insoluble in water over the time period required for a drilling operation at one range of water temperatures and highly soluble in water over a substantially higher range of water temperatures. Preferably the sleeve is substantially water insoluble at temperatures below about 100 F. and highly soluble in water having a temperature higher than about 150 F.

A readily available material having the desired w-ater solubility characteristics is a specially prepared polyvinyl alcohol. In accordance with one method the water solubility characteristics may be imputed to the polyvinyl alcohol depending upon the hydroxyl content of the polymer. Products containing from 70 to 85% of the original acetate groups are insoluble in water, but dissolve in aromatic hydrocarbons and aliphatic esters. When the residual acetate radicals are reduced to about 35%, solubility in organic solvents disappears and the product dissolves in cold water but precipitates on heating. At somewhat lower acetate content, the resin is soluble in both hot and cold water. When alcoholysis is as complete as possible so that only about ive percent or less of the acetate groups remain, the product is substantially insoluble in cold water but dissolves in hot water. The foregoing is one technique by which a polyvinyl alcohol material suitable for use in the present invention can be made. However, the method of making the material is no part of this invention. Suitable materials are available which might be made by other methods. Suitable polyvinyl alcohol materials are manufactured, for example, by the Reynolds Metals Company.

Neither the particular composition of the polyvinyl alcohol sleeve nor the method of making it form any part of the present invention. Any commercially available material having the desired water solubility characteristics may be employed. Such material should also have the requisite degree of toughness and strength to remain in place and provide a seal during the entire drilling operation.

With the sleeve 41 in place the drilling operation proceeds and water is jetted through the pipe I.at a temperature in the normal operating range such that it does not dissolve the sleeve 41. At the conclusion of the drilling operation, either before or after a concrete grout or other obstruction is emplaced in the end of the pipe 20, the sleeve 4I is removed by pumping hot Water having a temperature which causes the sleeve to dissolve. The pumping of the hot water continues for a time period requisite to effect complete dissolution of the sleeve.

It will be understood that usually the drilling operation will be accomplished using water in the normal ambient temeprature range of say 60 to 100 F. Moreover, it is convenient to use hot water in the range of say 150 to 212 F. to dissolve the polyvinyl acetate. Preferably, therefore, the water solubility characteristics of the polyvinyl alcohol are such that it is substantially insoluble in the range of 60 to 100 F. and highly soluble in water at a temperature from 150 to 212 F. It will be understood that the temperature ranges for water insolubility and solubility, respectively, may be varied. The magnitude of these ranges is not particularly important. The critical requirement is relative insolubility at a low temperature range and high solubility at a high temperature range. Drilling is then accomplished using water in the low temperature range and the sleeve dissolution step is accomplished using water in the higher temperature range.

Illustrated in FIGURE 6 is a sleeve 42 which may be mounted outside rather than inside of the pipe 20. In other respects the sleeve 42 is identical, particularly in its water solubility characteristics, with the sleeve 41. Since the sleeve is subjected to a high degree of abrasion when mounted outside of the pipe, it is preferred to place the sleeve inside.

Although the present invention has been illustrated and described with reference to a preferred specific embodi- Iment, it will be understood that various modifications may be made by persons skilled in the art without departing from the scope of the invention which is defined solely by the appended claims.

I claim:

1. A method of installing a well point system which comprises providing a plurality of well point pipes having upper and lower portions of uniform, noncircular cross sections, said pipes having open bottoms with side openings near said bottoms, sinking the lower portions of said pipes to a desired depth into the ground at spaced locations by,

simultaneously slidingly and drivingly engaging each of the pipes in a rotary drilling table having a noncircular pipe receiving opening to receive the noncircular pipe in driving relation and rotating the rotary table with the noncircular lower portion of the pipe extending into the ground to rotate said lower portion in the ground,

applying a downward force to each of the pipes, and

jetting water downwardly through each of the pipes while it being rotated,

thereafter obstructing said open bottoms below said side openings against admission of earth,

connecting a header to each of the installed pipes, and

connecting a pump to the header.

2. The method according to claim 1 wherein each of said well point pipe cross sections and said rotary table openings are square.

3. The -method according to claim 1 wherein a sleeve is positioned in closely fitting relation with each of said pipes to close said side openings prior t-o the sinking of said pipes, said sleeve being substantially insoluble in water over a normal operating range of temperatures and being highly soluble in water over a temperature range substantially higher than said normal range, said jetting being performed using water at a temperature in said normal operating range, and including the further step of passing water at a temperature in said higher range into the installed pipes for a time sufficient to dissolve said s eeve.

' 4. The method according to claim 3 wherein said sleeve 1s positioned inside of said pipe.

5. A method of installing a well point which comprises applying a sleeve in closely fitting relation with the lower portion of a well point pipe having an open bottom and strainer openings through the side of said lower portion so that said sleeve closes said openings,

said sleeve being substantially insoluble in Water over a normal operating temperature range and being highly soluble in water over a temperature range substantially higher than said normal range,

sinking said pipe to a desired depth in the ground while jetting water downwardly through said pipe at a temperature in said normal range leaving said sleeve intact, and

passing water into the thus sunk pipe at a temperature in said higher range for a time suicient to dissolve said sleeve.

6. The method according -to claim 5 further comprising the step of obstructing the bottom of said pipe below said strainer openings against the admission of earth after said pipe is sunk to said desired depth.

7. The method according to claim 6 wherein concrete is grouted into said pipe below said side openings to seal the lower end of the pipe after said pipe is sunk to said desired depth.

8. The method according to claim 6 wherein said insoluble temperature range is below F. and said soluble temperature range is above F.

9. The method according to claim 6 wherein said sleeve is made of polyvinyl alcohol having said water solubility characteristics.

10. 'Ihe method according to claim 9 wherein said -insoluble temperature range is below 100 E. and said soluble temperature range is above 150 F.

11. The method according to claim 6 wherein said pipe has a uniform noncircular cross section and is rotated during said sinking operation by la rotary table having a noncircular opening to slidably receive said pipe `in driving relation.

12. The method according to claim 11 wherein said pipe cross section and said rotary table opening are square.

References Cited UNITED STATES PATENTS 1,521,809 1/1925 Green 166-227 1,688,356 10/1928 Romney 175-314 2,226,804 12/ 1940 Carroll 166-227 2,835,328 5/1958 Thompson 175-314 3,169,586 2/1965 Bullard 175-320 3,215,213 11/1965 Morimoto 175-314 10 ERNEST R. PURSER, Primary Examiner.

NILE C. BYERS, JR., Examiner.

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