US1778574A

US1778574A - Retaining wall

Info

Publication number: US1778574A
Application number: US230435A
Authority: US
Inventors: Joseph H Thornley
Original assignee: WESTERN FOUNDATION Co
Current assignee: WESTERN FOUNDATION Co
Priority date: 1927-11-02
Filing date: 1927-11-02
Publication date: 1930-10-14
Anticipated expiration: 1947-10-14

Description

Filed Nov. 2, 1927 Oct. 14, 1930.

WWW A Ni nes Patented Oct. 14, 1930 UNITED sraras JOSEPH H. THORNLEY, OF CHICAGO, ILLINOIS, ASSIGNOR TO WESTERN FOUNDATION COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS w RETAINING WALL Application filed November 2, 1927. Serial No. 230,435.

The present invention relates to retaining walls such as are used in civil engineering operations for holding a bank of earth against sliding downwardly, for shoring up the side of a roadway cutting, and for similar situations where it is desirable to retain earth against lateral displacement.

The present form of retaining wall and method of supporting the same has been de- 0 vised primarily for supporting the sides of a roadway cutting which has been made along the side of a hill or through a ridge of ground. Accordingly I shall describe my invention in such embodiment, but it will be understood that the invention is not necessarily limited thereto. The accompanying drawing illustrating the invention shows a cross sectional view through a roadway cutting which has been made along the side of a slope, and illustrates the present retaining walls in profile. In this figure a naturalbank or slope corresponding to the side of a relatively steep hill is indicated at 1. The cutting, which is indicated generally at 2, is illustrated as being intended for the laying of railroad tracks 3, but it will be evident that such cutting might be intended for laying the road bed of a vehicular road or for any other purpose.

Where the steepness of the slope 1 is such that there is a possibility of the road bed i shifting or settling outwardly, it is desirable to reinforce or support the outer edge of the cut by a retaining wall 5. Retaining walls in this situation are usually imbedded in the soil to a considerable depth below the roadbed 4. These retaining walls are frequently constructed of L-shaped cross section with a relatively large footing or base portion 6 extending inwardly with reference to the slope. Such practice is followed in the pres ent instance, the vertical portion of the wall being constructed of reinforced concrete, and the footing or base portion 6 being also constructed of reinforced concrete. The point of juncture of the base 6 with the vertical por tion of the wall is heavily reinforced so that the earth pressure acting outwardly on the vertical portion of the wall cannot cause fracture at the angle between the base and vertical portions. According to the usual practice of erecting these walls, the base portion 6 is disposed at a considerable depth in the soil so that the weight of the soil superposed directly over this base portion will exert a considerable downward force th reon. This force is indicated at A, and it w i be evident that by making the portion of suliiciently large surface area, and by Viacing such base portion at a sufficient (lplll, the magnitude of the force A acting downwardly on this base portion may be made sufi'iciently large to withstand any lateral stress to which the vertical portion of the wall may be subjected. In many instances, particularly where the slope of the hill is relatively sharp, very little reliance can be placed upon the 7 at the outer side of the cutting for backing up the retaining wall 5 against outward pres sure; and in many instances it may not be practical to have this outer soil extend to any considerable height along the outward side of the retaining wall 5. Insuch cases, the anchorage aii orded by the base portion 6 must be relied upon substantially entirely to withstand the outwardly acting thrusting pressures bearing against the wall.

It will be observed that these pressures de velop a moment of force within the footing or base portion 6, tending to revolve the outer portion of the foot downwardly and to revolve the inner portion thereof upwardly. For convenience of reference I shallrefer to the outer portion of the base or footing as the heel thereof, such being designated 6 and shall refer to the inner extremity thereof as the toe, such being designated 6 It will also be noted that. when the base portion 6 is made suiiiciently wide, andis disposed sufficiently deep, to have the force A sustain entirely the lateral tipping forces set up in the wall, such force A is of maximum effect for resisting the moment of force tending to swing the toe 6 upwardly, but is of no efi ect for resisting the moment of force tending to swing the heel portion 6 downwarlly, the force A actually auginenting the downwardly acting moment of force. Where the base port-ion 6 is relied upon entirely to withstand the tipping forces Lie set up in the wall, it will be evident that it must be of considerable area and must be disposed at a considerable depth. This is frequently objectionable. owing to the cost of material necessary to constructing the base of a large area, and to the cost of excavating to the required depth for placing the base portion.

I propose avoiding these objections by sustaining the tilting moments of the wall on two rows of

piles

8 and 9 which are especially designed to sustain these forces. The outer row of piles 8 is intended to act in compression, the upper ends of such piles abutting against the heel portion 6 of the retaining wall. The inner row of piles 9 is intended to act primarily in tension, the upper ends of such piles being anchored to the toe portion 6 of the base 6. The outer pile. 8 may consist of wood piles, or of concrete piles either precast or formed in situ. These piles are sunk to a depth where they will have the required bearing value for sustaining the downwardly acting moment of force effective in the heel portion 6 of the wall. The inner piles 9 are preferably constructed of concrete, each being cast in place and having a large flaring pedestal portion 11 at its lower end for giving the pile the desired anchorage to resist tension stresses. The flaring or globular base 11 may be formed in accordance with any one of several well known methods of forming such piles. The tension piles 9 have a suitable reinforcing member or members extending therethrough, for increasing the tensile strength of the piles, and the upper ends of such reinforcing members are anchored in the base portion 6 of the wall, as by mechanically connecting the upper ends of such reinforcing members to the reinforcing members in the base portion 6. It will be understood that the

piles

8 and 9 are first sunk or driven to the desired depth, and that thereafter the retaining wall is formed with the base portion 6 thereof bearing in compression on the piles 8 and anchored in tension to the upper ends of the piles 9.

Numerous advantages are obtained by the foregoing construction. Because of the fact that the weight of the earth acting downwardly on the base portion 6 is not relied upon to any great extent for resisting tilting of the wall, such base portion need not be placed at any considerable depth below the road bed. Furthermore, owing to the fact that this base portion functions primarily as a force transmitting arm for transmitting compression and tension stresses to the piles S and 9, such base portion need not be nearly as wide as is ordinarily necessary when the weight of the earth acting on such base relied upon for preventing outward tipping of the wall. The shallower depth of the base portion, and the narrower Width thereof, made possible by the compression and

tension piles

8 and 9 thus effects a considerable saving of material, and also reduces the cost of excavating for laying the base portion.

The inner side of the out 2 is shored up by a retaining or breast wall i l which maintains the upper portion 16 of the slope in place. A retaining wall in this situation, where the banl: of earth which it retains slopes backwards to a higher level than the top of the wall, is commonly referred to as a sur charged breast wall. Such breast wall is also preferably of L-shaped cross section, comprising a foot or base portion 15. It r ll be observed that the pressure of the earth it against the rear side of the wall tends to tip the same outwardly, in much the same manner that the road bed 4; tends to tip the outer wall 5 outwardly. One manner of sustaining this outward pressure against the inner wall 1% is to extend the base portion 15 inwardly into the side of the slope, i. e., oppositelv to the direction shown. In such relation, oy making the base portion of sufficient area, and by placing it at a suilicient depth, the weight of the soil 16 acting downwardly on the base portion may be made to sustain. the outwardly acting forces on the wall. Such construction, however, is subject to the objections mentioned in connection with the outer retaining all 5. That to uay, the weignt of the soil 1G is effective for resisting upwardly acting moments of force in the toe extremity of the base, but is of no avail for resisting downwardly acting moments of force in the heel portion of the base. Furthermore, erecting the wall with the base portion extending inwardly into the slope requires the e:-:cavation of a very large mass of earth to lay the base portion, particularly in view of the fact that it must be placed at a considerable depth to sustain the large outwardly acting pressures on the wall. In many instances a factor of still more vital i1n portance, however, the horizontal dimension occupied by this base portion. For example, the rigzjht-of-way of the railroad compan v may be definitely limited in width, and it may be desirable to devote much of this width possible to track space. In an instance of this kind, the railroad companj may be precluded from extending any portion of the retaining yall 1 L inwardly be mnd the survey line indicating the inner side of their right-of-way. it will be evident, that in such case, if the base portion 15 extended inwarc ly into the slope in the manner above described, the inner e.- remity of the bas portion will have to to minute at the survey line, and this necessarily means that that portion of the i bbot-way occupied by the base portion (:2 int be devoted to track area. This loss of track area may be considerable; for example for a breast wall of 520 to 50 feet in height the base portion will have to be anywhere from 10 to 80 feet in width.

I propose avoiding these objections by extending the base portion 15 of the breast wall in an outward direction under the road bed 4. It will be understood that with the base portion extending in this direction the weight of the superposed soil bearing downwardly on such base portion is of no value for resisting the outward tipping of the retaining wall, and hence there is no need for placing such base portion at a considerable depth in the soil; in fact such base portion may lie directly below the ballast constituting the road bed 4. This form of retaining wal is made practicable by supporting the same on compression and tension piles in the manner described of the outer wall 5. The lateral forces set up in the retaining wall 14 establish downwardly acting moments of force in the toe or outer portion 15 of the base 15, and establish upwardly acting moments of force in the heel or inner portion 15 thereof. The downwardly acting moments of force in the outer or toe portion 15 are sustained on an outer row of compression piles 18 which are disposed underthe toe portion. The upwardly acting moments of force in the inner or heel portion 15 are resisted by an inner row of tension piles 19 which are anchored to the heel portion 15. These inner piles 19 have enlarged pedestal portions 21 which give the piles a large tension value for resisting upward pull thereon, and the reinforcing members in such tension piles are preferably connected directly to the reinforcing members in the base 15. It will be noted that both rows of

piles

18 and 19 are effective for carrying the weight of the retaining wall 14 and its base portion 15.

It will be observed that by constructing and sustaining the inner wall 14 in this manner, the inner or rear side thereof may be located directly on the survey line, and the horizontal space occupied by the base portion 15 may be utilized as track area. Furthermore, owing to the fact that the base portion 15 only functions as a force transmitting arm for transferring the lateral forces of the retaining wall to the

piles

18 and 19, such base portion need not be constructed as wide as would otherwise be necessary. 7

It will be observed that in the case of each

wall

5 and 14, the compression and tension piles also effectively anchor the wall against sliding bodily outwardly, either on its base or on a substratum of soil.

What I claim as my invention and. desire to secure by Letters Patent is:

1. In a supporting structure for maintaining a railway cutting in sidelong ground, the combination of an upwardly extending con crete breast wall having its inner side disposed substantially at the inner survey line reinforcing members in said base, and a row of compression piles sustaining the toe portion of said base, both rows of piles extending substantially vertically downwardly directly below said base whereby none of said piles projects inwardly beyond the survey line at the inner side of said wall.

2. I11 a supporting structure for maintaining a bank of earth, the combination of an upwardly extending breast wall having its inner side supporting the bank of earth, a

base integral with said wall and projecting laterally therefrom in a direction outwardly away from said bank of earth, tension piles anchored to the heel portion of said base, and compression piles sustaining the toe portion of said base, both series of piles extending substantially vertically directly below said base whereby none of said piles projects inwardly beyond the vertical plane of said inner side of the wall.

3. The combination with a roadway and an upwardly extending bank of earth along one side thereof, of a concrete retaining structure for retaining said bank of earth, said structure being of L-shaped profile comprising a substantially vertical wall portion and a substantially horizontal base portion, the inner side of said wall portion extending substantially vertically with the bank of earth bearing against the same, and the base por tion projecting from the other side of said wall portion away from said bank of earth and under the roadway, whereby no portion of the retaining structure projects into the bank of earth beyond the substantially vertical inner side of said wall and whereby the pressure of the earth bank creates upwardly acting stresses in the heel of said base por tion and downwardly acting stresses in the toe of said base portion, a row of substantially vertical tension piles anchored to the heel of said base portion to resist said upwardly acting stresses therein, and a row of substantially vertical compression piles sustaining the toe of said base portion to resist the downwardly acting stresses therein, said base portion being joined to said wall portion solely at the bottom of the wall portion whereby the roadway area can be extended approximately up to the substantially vertical outer side of said wall portion.

JOSEPH H. THORNLEY.