FIELD OF THE INVENTION
[0001] The present invention relates to an improved segmental retaining wall system.
[0002] More particularly, the invention relates to a segmental retaining wall (SRW) system
wherein each stackable block (also called "units", "SRW units" or "SRW blocks" hereinafter)
is provided with a tongue with a splitting groove that allows the user to construct
either a battered (inclined) or vertically aligned segmental retaining wall with the
same unit.
BRIEF DESCIRPTION OF THE PRIOR ART
[0003] Segmental earth retaining walls are a category of earth retention system that utilize
modular, dry stacked (no mortar), preliminary-cast concrete blocks to create a stable
mass with sufficient weight to resist earth pressures developed by the adjacent soil.
[0004] In this field, it is of common practice to use segmental modular earth retaining
wall blocks with a groove on their bottom side and a tongue on their upper side which
are offset with respect to each other to allow "automatic" vertical and horizontal
alignments of these blocks when they are assembled so as to form a uniformly inclined
wall. In this connection, reference can be made to US patent No. 4,490,075 granted
on December 25, 1984 in the name of A. RISI et al. Reference can also be made to Figures
1 a and 1b of the accompanying drawings, identified as "prior art" and to numerous
other utility patents and design patents that have been obtained over the last decades
by the inventor of record.
[0005] If SRW blocks with such an offset tongue and groove system to create a batter or
setback to the wall are commonly used, it remains that in design situations, a vertical
wall (vs. a setback wall) is more desirable, and therefore, the use of the SRW unit
in its current configuration (battered only) is limited. The following two examples
are illustrative of these situations.
a) Sidewalls to stairs
[0006] A stairway cut into an existing bank often requires retaining walls on either side
to support the earth cut. If battered retaining walls are constructed on either side
of the steps, the distance between the two walls increases as the steps ascend (see
Figure 12). This is due to the fact that with each step up, the wall offsets further
back. As the two walls are facing each other, the total width of the stairs increases
by an amount equal to twice the setback of the wall. With vertical sidewalls, the
stair width is maintained throughout the entire flight (see Figure 13).
b) Limited space at top of wall
[0007] In some design situations, the space at the top of the wall is limited, either due
to property lines, other structures, or simply a desire to maximize the usable land
above the wall. With a battered structure, the wall requires greater horizontal distance
at the top.
[0008] With the existing SRW blocks, due to the predetermined offset (X) between the tongue
and groove (see Figures 1 a and 1 b), the batter or setback of the wall is always
"automatically" achieved, resulting in a wall that may be engineered and constructed
with a known vertical alignment. The degree of batter or setback in a wall is a critical
element in the design with respect to the analysis and engineering performance of
the wall, geometric alignment, and aesthetic look. The batter of the wall is calculated,
in degrees, as the inverse Tan
-1 (X/Y)..
[0009] A problem with this kind of SRW system is that depending on the kind of wall to be
erected and the kind of inclination to be given to it, the modular, segmental retaining
wall blocks may substantially vary in shape and size. The moulds for such blocks are
precision manufactured from high strength steel and are designed to withstand high
stresses during the manufacturing process. As such, each mould is relatively expensive
and may only last for a specific length of time or number of manufacturing cycles.
In order to limit the costs associates with manufacturing a particular SRW system,
the intention is therefore to keep the number of components and therefore moulds,
to a minimum. With each additional mould, there are costs associates with not only
the direct purchase of the mould, but also, the manufacturing time lost when chancing
moulds, the increased complexity of managing additional components, and the increased
complexity of the system in general from a user perspective (education, inventory,
etc.).
SUMMARY OF THE INVENTION
[0010] It has now been found that the above mentioned problem related to a need for diversity
in the construction of a segmented earth retaining wall can easily be solved by using
SRW blocks each having a split key tongue, viz. a tongue provided with a splitting
groove that allows splitting of the tongue to make it smaller in width, and thus to
adjust at will the position of the SRW blocks and thus the shape of the wall to be
erected.
[0011] In other words, the split key tongue of each SRW block allows the user to construct
vertical and battered walls with the same blocks, thereby eliminating the need for
additional blocks and the costs and complexity discussed above.
[0012] Thus, the present invention is directed to an improved segmental retaining wall (SRW)
block for use to construct a segmental earth retaining wall. Like all the existing
block, the improved block according to the invention has:
- a front side;
- a top side with a transversal tongue of a given width projecting from it, the tongue
extending at a first distance from the front side; and
- a bottom side with a transversal groove made in it, the groove being sized to receive
the tongue of another similar block positioned below and thus to allow stacking of
the blocks, the groove extending at a second distance from the front side that is
smaller than the first distance;
- the first and second distance being selected so that the tongue and groove are offset
with respect to each other over a distance that is smaller than the width of the tongue.
[0013] In accordance with the invention, the improvement lies in that the tongue is provided
with a splitting groove sized and positioned to allow splitting of the tongue with
a splitting tool along a transversal line that is positioned to permit the remaining
portion of the tongue to fit into the groove of a further similar block stacked on
top of the present block with the front side of this further similar block extending
in a same vertical plane as the first side of the present block.
[0014] As a result, one may stack the above mentioned blocks as such, the resulting wall
being then battered, or one may stack the above mentioned blocks after having splitted
their tongues, the resulting wall being then vertical.
[0015] In accordance with a first preferred embodiment of the invention, the splitting groove
extends at an angle of preferably about 30° to guide the splitting tool at this angle
so as to impart a horizontal impact force to the portion of the tongue to be splitted
and thus facilitate such a splitting.
[0016] In accordance with another preferred embodiment of the invention, the splitting groove
has a bottom provided with a weak point preferably in the form of a 90° corner. This
weak point is located at the place where the splitting tool hits the bottom edge.
[0017] In accordance with a further preferred embodiment of the invention, the bottom of
the splitting groove extends below the top side of the block, thereby allowing formation
of a recess when the tongue is splitted.
[0018] The invention and its advantages will be better understood upon reading the following
non-restrictive detailed description made with reference to the accompanying drains.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019]
Figure 1 a identified as "prior art" is a side elevational view of a segmental retaining
wall constructed with blocks of conventional structure (see U.S. design patent No.
Des. 403,437 issued on December 29, 1998);
Figure 1 b identified as "prior art" is a larger view of two of the stacked blocks
shown in Figure 1;
Figure 2 is a front perspective view of a SRW block according to the invention;
Figure 3 is a side elevational view of the block shown in Figure 3;
Figures 4, 5 and 6 are enlarged side elevational views of the split key tongue of
the block shown in Figures 3a and 3b, showing in greater detail the sloped groove
made in it and the way it can be splitted;
Figures 7a and 7b are side elevational views of the split key tongue of the block
shown in Figures 3a and 3b before and after it has been splitted, respectively;
Figure 8 is a side elevational view of a segmental retaining wall constructed with
SRW blocks according to the invention, said wall being battered;
Figure 9 is a side elevational view of a segmental retaining wall constructed with
SRW blocks according to the invention, said wall being vertical;
Figure 10 is a side elevational view of three SRW units of the wall shown in Figure
8;
Figure 11 is a side elevational view of three SRW units of the wall shown in Figure
8;
Figure 12 is a side elevational view of a stair way cut with battered retaining walls
constructed on both opposite sides with SRW blocks according to the invention;
Figure 13 is a side elevational view of a stair way cut with vertical retaining walls
constructed on both opposite sides, said vertical walls being made from the same SRW
blocks as those used to construct the walls shown in Figure 12, after splitting of
their tongues.
DETAILED DESCRIPTION OF THE INVENTION
[0020] As clearly shown in Figures 2 and 3, the SRW block 1 according to the invention has:
- a front side 3;
- a top side 5 with a transversal tongue 7 of a given width projecting from it, the
tongue 5 extending at a first distance D1 from the front side 3; and
- a bottom side 9 with a transversal groove 11 made in it, the groove being sized to
receive the tongue 7 of another similar block positioned below and thus to allow stacking
of the blocks (see Figures 8 and 10), the groove extending at a second distance D2
from the front side that is smaller than the first distance D1.
[0021] As also shown, the first and second distances D1 and D2 are selected so that the
tongue 7 and the groove 11 are offset with respect to each other over a distance that
is smaller than the width of the tongue 7.
[0022] In accordance with the invention, the tongue 7 is provided with a splitting groove
13 sized and positioned to allow splitting of the tongue 7 with a splitting tool along
a transversal line that is positioned to permit the remaining portion of this tongue
to fit into the groove of a further similar block stacked on top of the present block
with the front side of this further similar block extending in a same vertical plane
as the first side of the present block (see Figures 9 and 11).
[0023] Thus, the present invention essentially lies in the incorporation of the above mentioned
splitting groove into a conventional SWR block provided with a tongue and groove system.
The incorporation of such a splitting groove allows the units to be stacked in both
battered and vertical alignments. Indeed, the splitting tongue within the tongue of
the SRW block allows the user to easily and clearly remove a portion of the tongue,
thereby allowing the blocks to be pushed forward to achieve a vertical alignment (see
Figures 3 to 7b).
[0024] As aforesaid, the splitting grooves gives the user the ability to stack the wall
at the predetermined setback (see Figures 8 and 10) or remove a portion of the tongue
and stack the wall vertically (see Figures 9 and 11).
[0025] As many applications require both vertical and battered wall alignments, the present
invention provides a means to increase the versatility of a SRW system and therefore
expands the use of the blocks. In particular, when segmental retaining walls are used
as sidewalls to a set of steps, the normal setback of the walls creates a widening
effect in the stairway as it ascends. As this widening effect can interfere with the
architectural alignment of the stairway and/or other structures, the use of vertical
sidewalls is often necessary. Such may now be built up with the same blocks.
[0026] As better shown in Figures 5 and 6, the split key tongue of the SRW block according
to the invention has a number of specific design elements which allow the user to
stack the units in a vertical alignment easily, without compromising the structural
integrity of the unit or the contact area between the blocks.
[0027] The first design element specific to the split key tongue lies in the dimensions
of split-off portion of the tongue (see Figure 4). In order to create a vertical alignment
by removing the split-off portion, the width of the mass removed, including the existing
groove, must equal the offset of the block. This width must actually be equal to the
X dimension shown in Figures 1 and 1 b.
[0028] A second of the design element specific to the split key tongue is that the splitting
groove extends at an angle, viz. is sloped. Such a sloped splitting groove is designed
to guide the splitting tool (usually a steel chisel) at an angle that is approximately
30 degrees below vertical. By delivering the impact force of the chisel (Fc) at this
angle, a component of the force is imparted to the block as a horizontal force (Fh).
It is this horizontal force that is required to create a tension crack between point
A and point B, the path of least resistance through the key (see Figure 5).
[0029] A third design element specific to the split key tongue lies in the presence of predetermined
weak point A at a very specific location (see Figure 6).The 90 degrees corner at point
A is a natural weak point in the groove. As the horizontal force (Fh) is applied above
this point, the concrete is forced into tension (Ft) in reaction to the clockwise
moment generates. In order to oppose this moment (Fh x Y) the material reacts with
a counter clockwise tension force. As concrete has little strength in tension, this
force creates a tension crack from point A to point B. By establishing the weak point
at A, the tension crack naturally propagates up from this point.
[0030] A fourth and last design element specific to the split key tongue lies in that the
splitting groove is recessed (see Figures 7a and 7b). As the SRW units are stacked
on top of one another, the contact surface between them must be perfectly level and
free of debris. In order to ensure that the rough split created between point A and
point B does not interfere with the contact area of the blocks, point A has been recessed.
As a result, the splitting plane propagates upward toward the surface of the block.
The split is limited to the surface of the block due to the fact that point B is another
natural weak point. The resulting split is therefore kept below the top of the block
and a clear contact area is maintained. Overall, the tension crack is controlled between
the two predetermined entry (A) and exit (B) points, allowing the split off portion
to be removed cleanly.
[0031] As discussed hereinabove in the Background of the invention, every additional component
in a SRW system generates significant costs with respect to the initial mould purchase,
changing moulds during manufacturing, inventory costs, and costs due to overall system
complexity (education, contractor familiarity). The incorporation of the splitting
groove according to the invention, advantageously allows the same block to be used
in both battered and vertical applications. Thus, such incorporation increases the
versatility of the system while limiting costs due to additional moulds, inventory,
etc.
[0032] Of course, numerous modifications could be made to the preferred embodiment disclosed
in detail hereinabove without departing from the scope of the invention. By way of
example, in the illustrated embodiment, the tongue and groove extends over the full
width of the SRW block. In practice, the tongue and even the groove could be shorter
in width, the only requirement being that there is always a possibility to stack rows
of blocks with the blocks of each row not necessarily vertically in line with the
blocks of the adjacent rows.
1. In a segmental retaining wall block hereinafter called SRW block for use to construct
a segmental earth retaining wall, said block having:
- a front side;
- a top side with a transversal tongue of a given width projecting from it, said tongue
extending at a first distance from the front side and
- a bottom side with a transversal groove made in it, said groove being sized to receive
the tongue of another similar block positioned below and thus to allow stacking of
said blocks, said groove extending at a second distance from the front side, said
second distance being smaller than the first distance,
- said first and second distance being selected so that said tongue and groove are
offset with respect to each other over a distance that is smaller than the width of
the tongue;
the improvement wherein:
- said tongue is provided with a splitting groove sized and positioned to allow splitting
of a portion of the tongue with a splitting tool along a transversal line that is
positioned to permit a remaining portion of said tongue to fit into the groove of
a further similar block stacked on top of the block with the front side of said further
similar block extending in a same vertical plane as the first side of the block;
whereby, in use, one may stack the above mentioned blocks as such, the resulting
wall being then battered, or one may stack the above mentioned blocks after having
splitted their tongues, the resulting wall being then vertical.
2. The improved SRW block of claim 1, wherein said splitting groove extends at an angle
in order to guide the splitting tool at said angle so as to impart a horizontal impact
force to the portion of the tongue to be splitted and thus facilitate such a splitting.
3. The improved SRW block of claim 2, wherein said splitting groove extends at an angle
of about 30°.
4. The improved SRW block of claim 2, wherein said splitting groove has a bottom provided
with a weak point, said weak point being located at a place where the splitting tool
hits said bottom edge.
5. The improved SRW block of claim 4, wherein the weak point is in the form of a 90°
corner.
6. The improved SRW block of claim 4, wherein the bottom of the splitting groove extends
below the top side of the block, thereby allowing formation of a recess when the tongue
is splitted.
7. The improved SRW block of claim 6, wherein said block is of a given width and the
tongue and the groove extend over all of said width.
8. The improved SRW block of claim 3, wherein:
- said splitting groove has a bottom provided with a weak point in the form of a 90°
corner, said weak point being located at a place where the splitting tool hits said
bottom edge; and
- the bottom of the splitting groove extends below the top side of the block, thereby
allowing formation of a recess when the tongue is splitted.
9. The improved SRW block of claim 8, wherein said block is of a given width and the
tongue and the groove extend over all of said width.