US2317016A

US2317016A - Bridge foundation and method of making same

Info

Publication number: US2317016A
Application number: US300482A
Authority: US
Inventors: Herschel H Allen
Original assignee: Individual
Current assignee: Individual
Priority date: 1939-10-20
Filing date: 1939-10-20
Publication date: 1943-04-20
Anticipated expiration: 1960-04-20

Description

April 20, 1943; ALLEN 2,317,016

BRIDGE FOUNDATION AND METHOD OF MAKING OF SAME Filed Oct. 20, 1939 4 Sheets-Sheet 1 6 I :l/yl I: .li l ll ll 4 I 0 J jflzrenfag 3 Hazard/2e April 20, 1943. H. H. ALLEN 2,317,016

BRIDGE FOUNDATION AND METHOD OF MAKING OF SAME Filed 001.. 20, 1939 4 Sheeca-Sheet 2 W Rye/72%;:

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BRIDGE FOUNDATION AND METHOD OF MAKING OF SAME Filed Oct. 20. 1939 4 Sheets-Sheet 3 W grade/JV lien 3% M Ff/flr April 20, 1943. H. H. ALLEN 2,317,016

BRIDGE FOUNDATION AND METHOD OF MAKING OF SAME Filed Oct. 20. 1939 4 Sheets-Sheet 4 l a? I1 I I. 15 A 30 I8 .4

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l I Q I .\r as! n Y imn/f'm d /1 6"! Patented Apr. 20, 1943 UNITED STATES PATENT OFFICE BRIDGE FOUNDATION AND METHOD OF MAKING SAltIE 4 Claims.

This invention has reference generally to improvements in that class of inventions known as bridges, and more particularly relates to an improved bridge or pier and method of making the same underwater and in very deep water and soft mud strata under conditions heretofore recognized by the engineering profession generally as the most diificult foundation conditions to be met by any type of subaqueous foundation construction.

The invention has particular reference to the construction of that class of underwater foundations in which stems, generally connected by diaphragm walls, usually of concrete, extend down- Ward to the bed of a river or other body of water, and there, or immediately below the river bottom, connected to and supported by one or more piles, which carry and distribute the weight of the stems and diaphragm walls and the superimposed loads thereon to firm strata below, which are capable, without settlement, to support such loads, Such foundations are frequently used to support bridges and other structures. This invention pertains particularly to those portions of such structures which lie below the surface of the water. In constructing foundations of this type, the procedure generally followed heretofore has been, after excavating or dredging the foundation site to the desired depth, to drive piles in an area enclosed by braced walls, which rise from the said site to some point above the surface of the water; and to then deposit a mass of concrete between and around the piles so as to seal the bottom. Such braced wall construction is known as cofferdams. a mass of concrete has been done by the commonly known Tremie method. As soon as the concrete has hardened sufficiently the enclosure or cofferdam has heretofore been unwatered, and the piles cut off close above the concrete seal. The heads of the piles have heretofore, then, been encased and capped by more concrete poured on the sealing concrete. In some cases it has been preferred to out the piles off, under water, and a little above the bottom of the excavation, and then to pour the seal course of concrete, encasing and capping the pile heads. Forms of the necessary dimensions have heretofore been built within this unwatered enclosure; reinforcement placed therein, and concrete poured. After the completion of'the structure to the water line, the walls (used only temporarily for construction purposes) and all material composing same has been removed at least to the top of the seal course. The cost of the construction of founda- The depositing of I tions by this method is high and the time required to construct is long on account of the large amount of temporary construction, the ma terials for which are used only during construction and then removed. The enclosing walls to form the cofierdam must be sufficiently watertight, as well as have sufficient strength to withstand the pressure of water down to the point to which it is to be unwatered and the enclosure must be kept free of water during the progress of the construction of the permanent parts of the foundation.

The primary object of the invention is the provision of a bridge or pier of the character described to be built in very deep water, and where the river bed does not offer sufficient support for a cofferdam or caisson of the types hereinbefore described as having been heretofore constructed. i

It is an equally important object of this invention to provide a pier of the above character, which is light in weight, and which has the further characteristics of satisfactorily resisting the lateral and longitudinal forces imposed upon a bridge pier.

More particularly the invention may be said to consist in the provision of a pier and a method of erecting or constructing the same consisting, briefly, in excavating a trench in the bottom of a river bed wherein the top soil is too soft or yielding to support a pier without piles; then, temporarily arranging pile clusters or dolphins at or beyond the corners of the trench: then taking a timber mat or other buoyant body and fixing the required number of pier bases thereon and positioning the same as by floating to a position above the trench: then driving guide piles through openings positioned substantially, centrally, or in other convenient positions of the base or bases on the mat; then sinking the mat with the base or bases thereon by applying a suitable weight thereto, if necessary, so that the mat is sunk to and rests in the prepared trench: then removing or cutting off the protruding or upper part of the guide pile or piles; then driving plumb and batter piles through openings provided in the mat or base form; then partially backfilling around the mat and the base or bases; then floating and sinking one or more steel shells with the lower portions thereof slightly telescoped within the pier bases on the mat; then filling the pier base or bases with a Tremie seal of concrete; then unwatering the steel shell or shell formed of other material, after having arranged anchoring means and reinforcing material Within the shells; and

finally filling the shells with concrete or the like, either below, or to, or above the water level of the river in which same is located.

It is further the object of this invention to provide a pier of the above character, which is simple in construction, wherein the number of parts are comparatively few; the use of temporary parts and materials are reduced to a minimum; the cost of production is low; and the time required for the erection or construction of same is short; and the efficiency of the resulting structure is high.

Other objects, as well as the nature, characteristic features and scope of the invention, will be more readily apparent from the following description taken in connection with the accompanying drawings, and pointed out in the claims which form a part of this specification.

The invention is clearly illustrated in the accompanying drawings, in which:

Figure l is a longitudinal'sectional view of the bottom portion of a-riverbed showing the excavated trench and showing timber piles driven into the trench area, and out 01f by'means of an underwater saw to :a predetermined elevation.

Figure 2 is a diagrammatic -plan view showing the position of the temporarily pile dolphins.

Figure 3is a top plan view of a mat to be used subsequently as abottom form with two steel bases thereon; the mat being connected to the dolphins prior to 'thesinking of the mat.

Figure 4 is a side elevational view'of the mat and steel cylindersto form steel pier bases prior to being sunk with guide pile driven in place.

"Figure 5 is a side-elevational view showingthe mat subsequently to be used as a bottom form and-pier bases after'having been sunk, and showing-also plumb and batter piles after having been driven into position.

Figure 6 is a fragmentary vertical sectional viewthrougha pier in its completed form, showing details -of construction of the various parts thereof.

Figure is a side elevational view of a complete pier constructed in accordance with this invention.

Figure 8 is a top plan'detail showing a slightly modified form ofpier for a four leg stem pier.

Figure?) is a fragmentary vertical elevational view througha pier with four stems in its completed'form, showing the details of construction above and immediately below the water surface.

Similar characters of reference are employed in an of the above described views to indicate corresponding :parts.

Referring now, more particularly, to the accompanying drawings, there "is provided in the bottom of a riverbed whether of a muddy or sandy nature, a trench "I, the trench being of suflicientdepth to 'insure that the piles supporting the pier :rnay'be protected by the surrounding i'nutl.'or'sand'inthe river bed after the trench ient locations, 'arerpiles or pile dolphins 2 for a purpose that will presently appear.

Driven into the trench are timber piles IA, the use for which will subsequently appear, cut

off to a predetermined'elevation by means of underwater or submarine saw.

Thereis now provided a mat 3 subsequently to :be used as abottom'form, which is preferably constructed on shore, and has fastened thereon in position one or more steel cylinders to form pier bases 4. In the present instance it is preferable to fasten two of such cylinders 4 to the upper surface of the mat, subsequently to be used as a bottom form, while positioned between the same is a suitable weight means, such as a sand box 5 for the purpose of sinking the mat after it has been arranged in the proper position.

The mat 3, subsequently to be used as a bottom form, is provided with openings 6, which are preferably positioned centrally of the bases A, but which may be positioned conveniently, and the mat is further provided with an additional series of openings 1. The mat is fastened to the pile dolphins 2 by suitable connecting means adjustable in any suitable manner, in order that the mat may be accurately positioned on the exact center line of the bridge and the exact center line of the pier prior to being sunk. Any suitable adjustable means may'be utilized in effecting the connection and for the purpose of illustration there are shown suitable cables 8 and turnbuckles 9.

In order to guide the mat with cylindrical bases thereon into a proper position prior to being sunk, guide piles H), which later are to be used in a permanent manner, are driven through the central opening 6 and into the river bed. The mat is now weighted and sunk by applying, for instance,'the necessary quantity of sand or gravel in the sand box 5. Obviously other suitable means may be employed for sinking the mat. In fact, in some instances, it is possible that the weight of the load of the cylinders would be sumcient to sink the mat. This sinking of the mat is controlled by means of cables ll or'may be controlled by means of cables assisting in loading the mat from derrick scows, or other floating equipment utilized for this purpose. It is to'be noted that the mat on contacting the previously cut off timber piles IA, or on contacting the bottom of a trench, acts as a support and a form for the bases. This is one of the important features of this invention, since the bottom form created by the sinking of the mat in the manner herein described, as will hereinafter appear by forming a bottom, prevents the Tremie concrete of the pier from being mixed with the soft, yielding strata forming thebottom of the river.

After the mat has been sunkto the position shown in Figure 5, the upper parts of the guide piles i0 are removed to facilitate the driving of the additional plumb piles l2 and the additional batter piles i3 through openings I 'inthe met.

It is to benoted that'the piles may be driven to exact position by "means of telescopic leads and.

with the use of an underwaterhammer, or that the piles :may be driven to exact position by means of a follower to be used inconiunction with fixedleads which may also be telescopic. It is also to be noted that the batter piles are'located only at the outside of the mat to overcome the effect of the longitudinal and lateral forces applied to the pier.

The next step may consist in the partial backfilling as at 14 of the space surrounding the mat and cylinder base with a portion of the material previously removed to form the trench.

The next step is the arranging of a steel shell l5 over each cylinder base 4. In the present instance, where there are shown two base members 4 thereare naturally two shells provided and they [are preferably connected as a reinforced steel Web I6 consisting of, for instance. spaced walls H reinforced and held in proper spaced relation by suitable steel struts or ties I 8. In sinking the interconnected shell, suitable cables l9 are operably connected with the pile dolphins or with floating derrick scows, or other floating equipment available at hand for the purpose, to facilitate the telescoping of the lower ends of the steel shells within the upper parts of the cylindrical bases to a position as shown, for instance, in Figure 6. In this connection, it is to be noted that the reinforced web I 6 has its walls joined with the shells in such a manner that it forms a buoyant body, and is highly instrumental in efiecting a proper sinking of the unit by permitting of the desired amount of water being pumped thereinto during the sinking operation; or the entire unit consisting of the two steel shells connected rigidly by the reinforced web l6 may be lowered into position by means of cables I 9 without effecting the watertight connection, but by allowing the cylinders and the entire connecting reinforced web to be entirely opened to allow water to pass freely between the side walls of the reinforced web and into the steel shells. If desired, temporary domes or caps may be applied to the top of the steel shells 15 to facilitate the floating of the same into position, the caps being removed prior to sinking of the shells.

The inner surfaces of the lower portions of the shells are fitted with suitable anchoring means 20, which will connect the upper shells to the upper end of the pile or Tremie concrete pier base. It has been found that this anchoring becomes necessary if the entire upper portions of the steel shell above the funnel sections are to be unwatered. Such anchoring, it has been found, is unnecessary, if all the concrete up to the surface of the water or within a short distance of the surface of the water is to be poured as Tremie concrete. The pier bases 4 are now filled with Tremie concrete 2| up to a point slightly short of the upper ends of the plumb and batter piles. The concrete is arranged in this space in any suitable manner as by pumping, or through a Tremie pipe, or in any other suitable manner, in case the major portions of the shells are to be filled with concrete in the dry, then after concrete 2| has set, the piles l2 and I3 are suitably capped as at 22. After the Tremie concrete has set, the next step is either the unwatering of the cylinder shells l5 and webs l6, after which suitable holes 23 are burned or otherwise provided in the shells so that the same are connected with the interior of the web, in order that suitable reinforcing rods 24 may be arranged from shell to shell and through the web so as to tie the parts together, so that after concrete 25 has been poured into the shells and the web the rods will act to tie the shells and the web together as a unit and insure the transmission of all vertical and horizontal forces to the pier bases; or the next step may be the pouring of additional Tremie concrete into shells l5 and webs I6, and the continuing of pouring Tremie concrete into these cylindrical shells l5 and webs i6 untii the water surface or a point immediately below the water surface has been reached by such Tremie concrete.

In some instances it has been found desirable to employ piers having more than two shells, for instance: as shown in Figures 8 and 9, where in a four stemmed pier is provided. In this instance, the construction is the same as that described in connection with the preceding form, with the exception that the longitudinal webs 26 terminate short of the water level and below the level of ice formation to minimize the effect of ice pressure on the piers.

Attention is directed to the fact that in actual use the guide piles Hi, the plumb piles l2, and the batter piles 13 may be of any form of piles, such as steel H piles, pipe piles, or combination pipe and H piles, or wood piles, or concrete piles, or, in efiect, any type of pile in use today.

Having thus fully described the invention what is claimed as new and desired to be secured by Letters Patent is:

1. A method of erecting a pier or like foundation consisting of excavating a trench in the bottom of a river bed, temporarily arranging pile dolphins at the corners of the trench, taking a perforated buoyant mat, fixing the required number of pier base shell members on the buoyant mat about the perforations, floating the mat into a position above the trench, adjustably connecting the mat to the pile dolphins to ensure of an accurate positioning of the mat, driving a guide pile through one of the perforations in the mat, applying weight to the mat to sink the latter along the guide pile so that the mat rests properly in the prepared trench, then removing the protruding upper part of the guide pile, then driving plumb and batter piles through other perforations in the mat, then partially back-filling around the mat and the base shell members thereon, then arranging pier shells with their lower portions slightly telescoped within the base shell members, then filling the base shell members with a Tremie seal of concrete, then un- Watering the pier shells, then capping the piles, then arranging anchoring and reinforcing material within the shells, and finally filling the shells with concrete with the latter filling engaging the capped upper ends of the piles.

2. A method of erecting a pier or like foundation under water without the use of a caisson comprising excavating a trench in the bottom of a river, temporarily arranging pile dolphins at the corners of the trench, taking a buoyant body and providing perforations therein, fixing at least two pier base shells on the upper surface of the body about the perforations, floating the body to a position above the trench, adjustably connecting the body to the pile dolphins in order to accurately position the same, driving guide piles through perforations in the buoyant body centrally of the base shells, applying weight to the body to sink the same along the guide piles so that the body rests properly in the prepared trench, then removing the protruding upper parts of the guide piles, then driving plumb and batter piles through the perforations in the body, then floating buoyantly connected steel pier shells and sinking the same so that the lower portions of the steel pier shells telescope within the pier base shells on the body, then filling the pier base shells with Tremie concrete, then un- Watering the steel pier shells, then capping the protruding ends of the piles, then arranging anchorin means and reinforcing material within the steel pier shells and their buoyant connection, and finally filling the steel pier shells and their buoyant connection with concrete.

3. A pier or like foundation including a mat provided with a plurality of pile receiving openings, a pair of pier base shells fixed to the mat, a back-filling arranged about the mat and partly about the pier base shells, plumb and batter piles arranged through the other openings in the mat and having their upper ends projecting above the mat, a pair of interconnected buoyant pier shells telescoped partly within the pier base shells, a pour of Tremie concrete arranged in the pier base shells on the mat and terminating short of the upper ends'of the plumb and batter piles and forming a base and acting to bind the base shells to the plumb and batter piles, caps arranged over the upper ends of the plumb and batter piles, anchoring means carried by the lower ends of the pier shells, reinforcing means in. the pier shells and the connection therebetween, and a second pour of concrete in the pier shells and their connection and about the upper projecting ends of the piles and the adjacent reinforcing and. anchoring means.

4. A pier of the character described including a perforated mat, pilesarranged through the mat and having their upper ends projecting above: the mat, a pair of metallic pier shells having their base portions open at the bottom and disposed on the mat and about the projecting ends of the piles and having their upper ends projecting considerably above the surface of the water, a reinforced Web connecting said pier shells and positioned beneath the surface of the water and above the level of the mat, a pour of Tremie concrete arranged on the mat Within the open bottom of the pier shells and terminating short of the upper ends of the piles to form a base and acting to bind the pier shells to the piles and a second pour of Tremie concrete filling said reinforced web and arranged in the pier shells on the first pour and bonded to the first pour and to the projecting end of the piles and to the pier shells and terminating adjacent the tops of the pier shells.

HERSCHEL H. ALLEN.