GB2412940A - Retaining wall - Google Patents

Abstract

A retaining wall is formed from a number of stacked blocks 20 where each of the blocks 20 has a stepped engagement portion 13 for engagement with a corresponding portion on an adjoining block. In such a way a gravity type retaining wall can be constructed without the use of mortar. The blocks 20 are hollow and formed from cast concrete and allow for the interior to be filled with soil to allow for plant growth. The front face of the blocks 20 may be convex and the wall may lean at an angle towards the embankment.

Description

1 241 2940 The versatile retaining wall.

Description:

Background

Concrete blocks for use in making both retaining walls and freestanding walls are well known.

A preferred version of such blocks must be adapted to certain criteria to result in a freestanding retaining wall, adapted to stacking that is economical and easily constructed by both residential and commercial user with limited equipment.

Further more the wall must be plantable with creeping plants such as ivy or flowers so that it becomes environmental pleasing. Manufacturing of the block must be simple and economical.

Architectural and site development organizations often use complicated retaining wall systems where economics is not of prime concern, however residential and commercial landscapers refuse to use complex retaining wall systems as the time and expense involved in constructing these walls is not economically sustainable given the price at which landscaping services are sold.

This invention provides the advantages of strength, simplicity, and low economic cost with a plantable wall block which has both open top and open bottom surfaces with a hollow void between them suitable for construction of reinforced and unreinforced retaining walls while allowing for the growth of plants carried not only by the blocks themselves but in addition, enables the roots of plants to bed into the backflil soil thus the plants may be used to decorate and strengthen the retaining wall against erosion.

It Is therefore a primary advantage of the present invention to provide this novel concrete block that is adapted for use to construct retaining walls of variable patterns exhibiting architectural appeal as described above Other concrete blocks do not provide the above or a means to interlock adjacent courses or rows of blocks with the course immediately above and below. Without such interlocking structures, a wall cannot be constructed with the desired strength. Similarly, known blocks have failed to provide a satisfactory and economical structure to allow interlocking of adjacent courses of blocks in a manner that results in a retaining wall that slopes at an angle of repose.

There is a need for an economical, plantable, concrete block for freestanding retaining walls that provides an esthetical pleasing front face, high strength, flexible, and is easily erected by unskilled folk without the use of mortar.

As can be seen the present state of the art of forming concrete blocks as well as the design and use of these blocks to build retaining structures has definite shortcomings.

SUMMARY

The present invention is directed to an apparatus that satisfies the above needs The Invention is a composite concrete block suitable for forming a retaining wall by dry stacking multiple blocks into successive overlying courses of blocks, said block comprising: a) A hollow block body, said hollow block body comprising a uniform hollow cylindrical shape.

All front surface and a back surface, having a convex surface, said front surface and said back surface being substantially parallel to each other and separated by a distance comprising the depth of the block, a generally planar upper surface and a generally planar lower surface, said upper surface and said lower surface being substantially parallel to each other and separated by a distance comprising the height of the block to thereby permit generally parallel alignment between the upper surface of a block and the upper surface of the adjacent blocks in the next adjacent course of blocks, said lower surface having the same area as said upper surface, with portions of the lower surface of the block being configured to rest on portions of the upper surface of the adjacent blocks in the next lower course of blocks when they are formed into a wall in a manner to cause the upper surfaces of adjacent courses of blocks to be in a substantially parallel relationship.

b) A lip extending upwards from the block upper surface plane, said lip comprising a setback surface and a locking surface, to allow the said setback surface extending from the upper front edge of the hollow block to provide a sufficiently tall abutment to easily and consistently align the block over a lower course of blocks so preventing sliding of the wall.

Retaining walls are often designed with a "setback" at an angle to the vertical to counter the pressure of the soil behind the wall. Setback is generally considered the distance which one course of a wall extends beyond the front of the next highest course of the same wall. As in this case where the blocks are of the same proportion, setback is regarded as the distance which the front surface of a higher course of blocks extends backwards In relation to the front surface of the lower wall courses. In vertical structures such as retaining walls, stability is dependent upon the setback between courses and the weight of the blocks.

- Each b!oc.k masonry u nit has Fiord spaces or onennns (rarest extenrJinn vertiraliv there through. Each horizontal course of said blocks are stacked offset by a distance, equal to half the diameter of the said hollow concrete block. This allows said block to sit between the two blocks below, such that half an opening in the blocks In one row coincide with half the openings In bottom rows and so on, upwardly from a first row to a top row.

d) Each block weighs 30kg and Is increased by 33kg when filled by wellcompacted material, having a density 1800 kg/m3 to give a total of 63 kg.

Each individual block Is filled with compacted granular soil thereby being fully plantable as well as being available in various colours to complement the environment: As with most retaining structures it is desirable that the material used for backfill be a granular free draining son in order to prevent pore pressure build-up. If this is not practical some form of drainage behind the wall will be necessary. However, in normal conditions the vertical joints between the blocks provide adequate drainage, preferably strips of non woven geotextile material may be affixed over these gaps before replacement of the backfill soil.

This allows for relatively easy and rapid construction, stability of the wall during construction, regardless of height or length, relative flexibility with respect to lateral deformation and differential vertical settlements, and, importantly, economic advantages.

e) The convex front face of such blocks may be moulded to provide a decorative finish or the like, which is generally employed solely for aesthetic purposes. The sidewall surfaces are generally solid and the sidewall surfaces can include one or more notches to facilitate the alignment of the blocks and thus the rows.

f) Concrete masonry units are generally identified and specified by reference to their dimensions such as width (W) by height (H) by length (L) and in any combination of these dimensions. These units may be termed "cored" By definition, masonry units, which are cored in excess of 25%, are termed "hollow" units, wherein the measurement of coring is one of determining the percentage of void area in the cross-sectional plane parallel to the bedding plane of the unit The hollow concrete blocks below are Just 2 of the embodiments of the invention 1) A cylinder Fig 2 having in the metric system: Diameter of 460mm i.e. and H1 =250mm, H2 = 240mm and H3 = 1 Omm, nominally referred to as a 460mm hollow cylindrical block.

2) A hexagon Fig 3 having in the metric system: length L=460mm, W=400mm and face F1 = 230 and H1 =250mm, H2 = 240mm and Ha = 10mm nominally referred to as a pentagon or hexagon These measurements allow the maintenance of the appropriate weight to diameter ratio of the block, provide a block weighted to allow manual transport by one person, and ensures optimal efficiency in the use of machinery and capable of being mass produced by automated block-making machines, i.e. to provide a method of using a block mould as Fig 7, to fill the mould, subjecting the fill to pressure, and ejecting the formed concrete blocks from the mould.

The top surface of each block is provided with a 10mm step which gives the interlock action in the horizontal plane This abutting engagement between the upper and lower blocks in adjacent courses forms the interlock that prevents the block in the upper course from moving forward. This interlock enables the blocks in the upper courses to resist the pressure of the earth behind the wall. The blocks are plantable to allow plant growth to cover the face.

Landscape specialist can assist with exotic flowers and foliage, however where professional advice is too costly, the wall should be planted with hardy evergreen creeping plants such as ivy.

Fertilizers should be used with caution as they may affect the integrity of the concrete.

In addition the growth pockets should allow for free drainage of moisture In order to prevent root saturation. Excessive or continual watering should be avoided as this may lead to pressure, causing stability problems, and possible wall failure.

These are critical features of the present invention.

A brief description of the drawings will show features, aspects, and advantages of the present invention and thus become better understood.

Description of the preferred embodiment.

While this invention is susceptible of embodiments in many different forms, the drawings show and the specification describes in detail a preferred embodiment of the invention. It should be understood that the drawings and specification are to be considered an exemplification of the principles of the invention. They are not intended to limit the broad aspects of the invention to the embodiment illustrated.

Where:

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Fig.1 is a side view of a retaining wall built with a number of concrete blocks. It is a cross sectional side elevation of the wall construction depicted in Fig. 5.

The construction, proceeding upwardly from the unexcavated natural soil 19, includes concrete foundation 18 on which are stacked rows of precast concrete blocks 20 having conventional lip formed integrally with the upper face of the block. The lip 13 & 28 is adapted to establish a uniform set back from course to course when pluralities of like blocks are laid in courses and enabling such blocks to fit mechanically and snugly together, row upon row, to thereby prevent any shifting of blocks with respect to each other.

Illustrates the plant-receiving cavities being provided by the laterally staggered nature of the blocks in superimposed courses and may be used to decorate and strengthen the retaining wall against erosion.

Soil fill will produce, in effect, a standard gravity wall with a relatively flexible facing.

Fig 2 is the top view of the cylindrical concrete block Fig 3 is the top view of the hexagonal concrete block Fig 4 Is a side view and crosssectional view of the cylindrical concrete block Fig 5 is a side view and cross-sectional view of the hexagonal concrete block Fig 6 is an end view of the cylindrical concrete block showing the cavity and having a protrusion "lip" H3 defined on the top face.

Fig 7 Is a top view of a freestanding retaining wall built with a number of cylindrical concrete blocks showing the method for construction using the invention.

Fig 8 depicts In front elevation the assembly of block facing elements 33 in staggering and overlapping array, as shown, all stacked in rows upon foundation 18.

Fig 9 Shows the manufacturing process to produce the invention through mass production by automated block-makng machines.

Fig 10 Is a perspective view of an alternative embodiment of the invention 33 In construction of an unreinforced mortarless retaining wall while allowing for the growth of plants 35 Dry, precast modular concrete block facing elements (3) are stacked in rows, as shown, having staggered, overlapping orientation to one another row-to-row, and engaging each other in a conventional abutting engagement fashion, as shown and described in more detail in (5) Illustrated is the construction of the mortarless retaining wall by stacking courses of said blocks, filled and tamped with soil, successive courses of blocks are then stacked on top of preceding courses while backfilling the wall with soil (1) Blocks are stacked one on top of another and in side-by-side relationship to avoid gaps between adjacent blocks, in generally horizontal rows. The vertical joints between the blocks also provide adequate drainage.

(2) Bulk earth form is retained by layers of backfill soil and compact to specified density adjacent the rear face of the wall. Fill to the top of the last row of blocks (3) The front face of the retaining wall - the convex front face of such blocks may be moulded to provide a decorative finish or the like, for aesthetic purposes.

(4) Illustrates position of block placed on top of preceding courses before filled and tamped with soil.

(5) The top surface of each block is provided with a 1 Omm (H3)step which gives the interlock action in the horizontal plane This abutting engagement between the upper and lower blocks in adjacent courses forms the interlock that prevents the block in the upper course from moving forward. This interlock enables the blocks in the upper courses to resist the pressure of the earth behind the wall.

(6) Blocks are 'anchored'to each other by' 10mm step tongue (13) (7) As construction of the wall proceeds from the foundation 18 upwardly, tamped fill soil is l placed as necessary in block The proper combination of blocks makes it possible to construct gravity walls to significant heights without additional soil reinforcement. The maximum height of such a wall will depend on several factors such as the dimensions of the blocks, number of parallel blocks producing a row, properties of the backfill soil and the foundation soil, external forces, and the design earthquake intensity. Typically, the maximum height of an unreinforced single row wall is 3 meters and with double rows of blocks heights above 6meters are obtainable Taller walls may be constructed with reinforced soil. Reinforcement materials to be employed include galvanized steel grids, geotextles, geogrids, and/or ground anchors (i. e. prestressed tiebacks and/or soil nails). The economics resulting from the natural soil terrain may dictate a combination of ground anchors together with planar reinforcement materials To construct a gravity wall, the following steps are preferably undertaken: l. Excavate a ditch 24 for the levelling foundation pad 18 to a minimal depth 31 of 600mm, the addition of a toe 23 to the levelling pad can be included for increased stability.

The width 22 of the ditch should be the diameter of the first row of blocks plus half again i.e. typically 690mm.The top of the levelling foundation pad should be at least 30 cm below the final grade of the soiHn front of the wall 19, or as otherwise specified by the design engineer.

2. Pour concrete into the excavated ditch to form the levelling foundation pad, preferably concrete with a minimum compressive strength of 200 kg/cm2.(1:2:4) Steel to reinforce the concrete should be used if specified.

3. After positioning and levelling, bed the first row of blocks 21 into the wet concrete levelling foundation pad 18.

4. Place layers of backfill soil behind the row of blocks and compact to specified density 26.

fill the volume of voids in each block 26 with compacted granular soil to the top of the first row of blocks.

5. Place another layer of blocks on top of the first row staggered, by half the diameter of a block as shown in Fig 5. The upper surface of each block Is provided with a 1 Omm (H3) step 13 which gives the "anchor interlock action" in the horizontal plane allowing the row above to easily and consistently align the block over a lower course of blocks so preventing sliding or slipping of the wall forward 6 & 13.This offset 15 ensures an even amount of setback for straight and curved portions of the wall while the height of the blocks 16 prevents the slope of the wall 17 becoming vertical. Typically the angle off the horizontal is degree to the horizontal 29.The volume of voids in each block 26 is filled with compacted granular soil.

Place backfill soil 14 in layers and compact to meet specifications; fill to the top of the row of blocks.

Soil fill will produce, in effect, a standard gravity wall with a relatively flexible facing.

6. Repeat steps 4,5, for additional rows of blocks and layers of backfill, until the desired height is obtained

Claims (1)

1. We claim as oumnvention the following This invention is a plurality of

   precast, hollow modular concrete block units which Includes dry cast, unreinforced modular wall blocks with anchor type tongue on the uppersurface, stacked one on top of another and In side by side relationship to avoid gaps between adjacent blocks, In generally horizontal rows extending vertically upwardly from a first row resting upon a foundation plane adjacent a bulk earth form to be retained. This retaining wall block Is therefore suitable for use in forming a mortar less retaining wall by stacking courses of said blocks, filled and tamped with soil, successive courses of blocks are then stacked on top of preceding courses while backfilling the wall with soil Of the four basic classes of retaining walls, i. e., gravity, cantilever, anchored and mechanically stabilized backfill, the present invention relates primarily to the first. By way of background, gravity walls depend upon the weight of the wall itself to prevent overturning and sliding of the wall