RETAINING WALL SYSTEM

Abstract

The present invention concerns embodiments of a block subassembly, a building block system and methods for constructing a retaining wall. In an illustrated embodiment, a block subassembly includes at least a first block and a second block and an adjustable connector which extends between the first and second blocks and is connected to the blocks. The adjustable connector is configured to have an adjustable length to adjust the spacing between the first and second blocks. In particular embodiments, the adjustable connector is pivotably connected to the first and second blocks.

Description

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims the benefit of U.S. Provisional Application No. 60/964,311, filed Aug. 10, 2007, which is incorporated herein by reference.

FIELD

The present invention concerns embodiments of construction blocks, connectors and structures made therefrom, and more particularly to retaining wall blocks and retaining walls for retaining slopes of earth.

BACKGROUND

Conventional retaining walls are used to secure earth embankments against sliding and slumping. Retaining walls are made of various materials such as concrete, solid masonry, wood ties, bricks and blocks of stone and concrete. Typically, blocks are placed in rows overlaying on top of each other to form a wall. One specific approach for building a retaining wall was shown in U.S. Pat. No. 5,350,256 to Hammer. In this approach, the retaining wall comprises vertically-stacked courses, each comprising a series of I-shaped subassemblies placed side-by-side in respective courses. Each subassembly is comprised of face and tail blocks that are connected by a trunk block extending between the face and tail blocks. The chambers defined between adjacent I-shaped subassemblies are filled in with backfill.

Despite such inventions, there exists a continuing need for new and improved systems, block subassemblies and methods for constructing retaining walls.

SUMMARY

According to one aspect, the present invention provides a new and improved adjustable connector for use in block subassemblies that are used to construct retaining walls. According to one embodiment, the adjustable connector is configured to interconnect first and second spaced-apart blocks and has an adjustable length to adjust the spacing between the blocks to form block assemblies of different depths. According to another embodiment, the connector is pivotably connected to one or both of the first and second blocks to permit pivoting of the connector in a horizontal plane relative to one or both of the blocks.

According to one representative embodiment, a block subassembly comprises a first block, a second block and an adjustable connector which extends between and is connected to the first and second blocks. The second block is spaced from the first block such that the blocks define a space between them to receive backfill material when constructing the wall. The length of the adjustable connector can be adjusted to adjust the spacing between the first and second blocks. Typically, in prior art systems such as described above, multiple block subassemblies are placed end-to-end in the lower courses of a retaining wall. Advantageously, utilizing a block subassembly with an adjustable length connector can reduce the number of required subassemblies at the base of a wall, thereby reducing the amount of materials and time required for constructing the wall.

In one illustrated embodiment, the adjustable connector comprises an inner tube nested within an outer tube such that the inner tube is telescopically slidable into and out of the outer tube to adjust the length of the connector. The inner and outer tubes can have a plurality of respective longitudinally spaced alignment holes sized to receive a retaining pin. Once the connector is adjusted to its desired length, the pin can be inserted through an alignment hole in each of the inner and outer tubes to restrict relative longitudinal movement between the tubes.

According to another representative embodiment, the present invention provides a building block system for building a retaining wall using a plurality of face blocks each having a rear face, a plurality of tail blocks each having a front face and a rear face, and a plurality of adjustable connectors each having first and second end portions. The length of each adjustable connector between its first and second end portions can be adjusted. The face blocks, tail blocks, and adjustable connectors can be assembled into respective block subassemblies. Each subassembly can be formed by connecting the first end portion of an adjustable connector to the rear face of a face block. The adjustable connector extends rearwardly from the rear face of the face block and is connected at its second end portion to the front face of a tail block. In certain embodiments, the tails block can be adapted to be connected to an adjustable connector at its rear face to allow additional adjustable connectors and tail blocks to be added to the subassembly to extend the subassembly deeper into the slope of the wall for added anchoring strength.

According to another representative embodiment, a retaining wall comprises at least first and second vertically stacked courses or layers. Each course can be constructed by placing several block subassemblies side-by-side along the length of each course. Each block subassembly includes a face block having a front surface exposed in a face of the wall, a tail block positioned behind and spaced from the face block, and an adjustable connector extending between the two blocks and connected to the face and tail blocks. The length of the adjustable connector can be adjusted to adjust the spacing between the face and tail blocks.

According to another representative embodiment, a method of constructing a retaining wall is provided. The method includes forming at least first and second vertically-stacked courses each comprising a plurality of block subassemblies. At least some of the block subassemblies include a face block, a tail block and an adjustable connector, the length of which can be adjusted to adjust the spacing between the face and tail blocks.

According to another representative embodiment, a block subassembly for constructing a retaining wall comprises a first block, a second block spaced from the first block, and a connector comprising an elongated body having first and second opposite end portions. The first end portion is connected to the first block and the second end portion is connected to the second block, and the connector is pivotable relative to at least the first block to permit adjustment of the angle between the connector and the first block.

The foregoing and other features and advantages of the invention will become more apparent from the following detailed description of several embodiments, which proceeds with reference to the accompanying figures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a retaining wall, according to one embodiment. FIG. 2 is a top plan view of a block subassembly used to construct the wall shown in FIG. 1.

FIG. 3 is a top plan view of the adjustable connector of the subassembly shown in FIG. 2.

FIG. 4 is a top plan view of the adjustable connector shown in a disassembled state.

FIG. 5 is a side elevation view of the adjustable connector shown partially in section.

FIG. 6 is a perspective view of a face block of the block subassembly shown in FIG. 2.

FIG. 7 is a perspective view of the tail block of the block subassembly shown in FIG.2.

FIG. 8 is a top plan view of another embodiment of an adjustable connector.

FIG. 9 is a top plan view of the adjustable connector of FIG. 8 shown in a disassembled state.

FIG. 10 a side elevation view of the adjustable connector of FIG. 8 shown partially in section.

FIG. 11 is side view of the lowermost course of a retaining wall, according to another embodiment.

FIG. 12 is a perspective view of an embodiment of a block subassembly utilizing pivotable dovetail connector elements shown in a disassembled state.

FIG. 13 is a top plan view of the block subassembly shown in FIG. 12.

FIG. 14 is a top plan view of another embodiment of a block subassembly.

FIG. 15 is a cross-sectional view of the block subassembly of FIG. 14 taken along line 15-15 of FIG. 14.

DETAILED DESCRIPTION

As used herein, the singular forms “a,” “an,” and “the” refer to one or more than one, unless the context clearly dictates otherwise.

As used herein, the term “includes” means “comprises.”As used herein, a group of individual members stated in the alternative includes embodiments relating to a single member of the group or combinations of multiple members. For example, the term “a, b, or c,” includes embodiments relating to “a,” “b,” “c,” “a and b,” “a and c,” “b and c,” and “a, b, and c.”

FIG. 1 shows a retaining wall 8 for retaining a sloped bank 6 against sliding and slumping. The wall 8 is formed of several vertically stacked courses or layers 4a-4d. Each layer 4a-4d is generally horizontal and extends in a rearward direction A into the bank 6.

Each layer in the illustrated embodiment is formed of a row of side-by-side I-shaped subassemblies 10. Each subassembly typically includes at least two vertically oriented planar blocks and an adjustable connector extending between or connected to the blocks. As shown in FIG. 2, a veneer or face block 24 can have a textured face surface 26 facing a forward direction B opposite the rearward direction A. The adjustable connector in particular embodiments comprises a nested tube subassembly 68, which is attached to the rear of the face block 24, desirably at a vertical medial junction thereon. The nested tube subassembly desirably extends perpendicularly from the face block 24 in the rearward direction A. A tail block 18 can be attached to the rearward end of the nested tube subassembly 68 so that it is parallel to the face block 24, with the nested tube subassembly being attached to the tail block desirably at a vertical medial junction. In some exemplary embodiments, the adjustable connector 68 can extend rearwardly from the face block 24 at an angle that is less than 90 degrees (FIG. 13).

For additional anchoring stability, particularly in the lower layer 4a of walls having several layers, the I-shaped subassemblies 10 can be elongated in the rearward direction A by attaching one or more extension subassemblies 40. The lowest layer desirably extends into the slope a distance approximately equal to one-third of the final wall height. The extension subassembly 40 includes a tail block 18 attached perpendicularly to a nested tube subassembly 68 in a T-shaped arrangement. In each extension subassembly 40, the nested tube subassembly 68 desirably attaches to and extends perpendicularly from the center of the tail block 18 of the standard I-shaped subassembly 10.

In the retaining wall 8 shown in FIG. 1, the I-shaped subassemblies 10 are placed side-by-side so that their nested tube subassemblies 68 are generally parallel and the face blocks 24 are positioned end-to-end in a continuous line. Thus, a pair of adjacent I-shaped subassemblies defines a generally rectangular chamber 38 suitable for filling with backfill material 46 to provide stability and drainage. Each chamber 38 is defined at its sides by the nested tube subassemblies of the respective I-shaped subassemblies and at its front and rear by the face blocks 24 and tail blocks 18 of the respective I-shaped subassemblies. In certain embodiments, as described in greater detail below, utilizing adjustable connectors which are pivotally connected to the face and tail blocks (FIG. 12), a pair of adjacent subassemblies may form a non-rectangular chamber.

As further shown in FIG. 1, the successive layers 4a-4d can be staggered and can be set back by a small distance to create a slightly sloping wall face. Nonetheless, each face block 24 rests on the face blocks of the layer below and each tail block 18 rests on the tail blocks of the layer below, with each nested tube subassembly 68 being suspended above the chamber 38 below. The face blocks 24 can be wider than the tail blocks 18 so that convex curved walls may be formed by bringing together adjacent tail blocks 18 closer than a parallel spacing would ordinarily dictate. To form a concave wall, the tail blocks can be spaced apart wider than ordinarily dictated but not so far apart that each tail block 18 does not rest on the ends of the spaced apart tail blocks of the layer below. If a more sharply concave wall is desired, separate tail blocks may be added to support any unsupported members.

As shown in FIG. 2, the face block 24, nested tube subassembly 68, and tail block 18 can be assembled to provide an interconnected I-shaped subassembly 10. In the interconnected state, the components of the subassembly may not be disconnected or separated in any lateral direction without breakage. The components of the subassembly in the illustrated embodiment are not merely held in place by frictional forces and the presence of adjacent unconnected blocks. Each component desirably is securely mechanically engaged to at least one other adjacent component.

The subassembly components in certain embodiments can be interconnected by dovetail joints so that they may be separated only by vertically sliding one block with respect to the attached block. A dovetail joint may be formed in any of a wide variety of geometries as long as the blocks are connected against lateral separation. Dovetail joints generally have a male key or tongue 50 that mates with a female slot or groove 52. Typically, the tongue is wider at some position toward its free end than at another position closer to its root. The female groove 52 desirably is configured to closely conform to the male shape. In the illustrated embodiment, the face block 24 and tail block 18 define the vertical grooves 52, which are generally trapezoidal, with the face being wider than the aperture at the surface of each block. Compatible male tongues 50 are provided on the ends of the nested tube subassembly 68, with the free end being wider than the root.

In alternative embodiments, the subassembly can be held in place by frictional forces and/or the presence of adjacent unconnected blocks. In such embodiments, flat plates can be attached to the opposite ends of the adjustable connector 68 rather than male tongues 50, which plates are sized and shaped to be inserted into compatible slots or openings in the blocks 18, 24.

FIG. 3 shows the assembled nested tube subassembly 68 with a male tongue 50 at each end thereof. Each tongue 50 can have a sloped lower end surface (not shown) corresponding to a sloped end surface 56 of the female groove 52 (FIG. 6).

FIG. 4 shows the component parts of the nested tube subassembly 68 in a disassembled state. The subassembly in the illustrated form comprises an inner tube 70 that is inserted into and therefore nests within an outer tube 72. The tubes 70, 72 are configured to be telescopically slidable relative to each other to adjust the overall length of the subassembly 68. The nested tubes can be connected by a pin 76 (FIG. 5) that is inserted through alignment holes 74 formed in the inner and outer tubes 70, 72. The alignment holes 74 allow the nested tube subassembly 68 to be adjusted and maintained at a desired length by connection of the nested tubes through insertion of a connecting pin 76 into selected alignment holes 74 in the tubes. FIG. 5 further shows the assembled nested tube subassembly 68 in cross section to illustrate the passage of the connecting pin 76 through the alignment holes 74 of the outer and inner trunk tubes. In the illustrated embodiment, alignment holes 74 are formed on diametrically opposing sides of each of the inner and outer tubes to allow the pin 76 to extend completely through both tubes. In alternative embodiments, the tubes 70, 72 can have alignment holes 74 formed only along one side of each tube such that the pin 76 can extend into but not completely through the tubes.

In particular embodiments, the length of the connector 68 can be adjusted between 24 inches and 44 inches, which would be desirable for constructing walls having a height of 10 feet or less. For taller walls, the connector 68 can be adapted to have a greater maximum length.

While in the illustrated embodiment the inner and outer tubes 70, 72 are cylindrical, the tubes can have other cross-sectional shapes. For example, the tubes 70, 72 can have a cross-sectional profile that is square, rectangular, triangular, or various combinations thereof, to name a few.

The inner and outer tubes 70, 72 can be made from various materials. For instance, the tubes 70, 72 can be formed from plastic or metal pipe and can have a plate welded or otherwise attached to an end of each pipe for connecting to a block.

The nested tube subassembly 68 can be used to adjust the overall length of the I-shaped subassemblies 10. In particular examples, such an adjustable I-shaped subassembly can enable a retaining wall 8 that can conform to particular contours of the sloped bank 6. In other particular examples, such an adjustable I-shaped subassembly 10 can reduce the number of required extension subassemblies 40 (FIG. 1) and thus reduce the materials needed for constructing retaining wall 8.

FIG. 6 shows the face block 24 with the groove 52 only partially bisecting the block. The groove in the illustrated embodiment does not entirely pass through the block, but terminates at an end surface 56 that can be sloped in a direction facing generally upward and rearwardly of the block. Thus, the lower portion of the block desirably is solid and unbroken by the groove, thereby increasing the strength of the block and decreasing the risk of breakage at the groove 52.

The face block 24 can further include alignment channels 58 defining oblong bores 62 passing vertically through the entire block. Each alignment channel 58 can include a rear pocket 60 in communication with the alignment channel 58 and extending to a limited depth. An alignment plug 30 (FIG. 1) comprising a rectangular lower portion 32 and a pin shaped upper portion 34 can be used to interconnect vertically adjacent blocks. The lower portion 32 can be inserted into the alignment channel 58 of a block such that the upper portion 34 extends upwardly and into an alignment channel 58 in an overlying block. The pin 34 desirably is offset toward one end of the lower portion 32 of the plug to permit construction of vertical courses (i.e., no setback) or courses that are set back relative to each other. If zero setback is desired (the face blocks are vertically aligned), the alignment plug 30 is placed in an alignment channel in a forward position such that the pin 34 extends upwardly from a location closer to the front portion 62 of the alignment channel 58. To create a setback between two courses, the alignment plug 30 is placed in an alignment channel in a reversed position such that the pin 34 extends upwardly from a location closer to the rear pocket 60 of the alignment channel 58. The alignment holes desirably are generally centered on points ¼ and ¾ of the distance along the length of the face block 24. In alternative embodiments, the alignment channels 58 can be used to retain vertical reinforcing bars passing vertically through several layers of the wall. In addition, the alignment channels 58 are desirably elongated to provide lateral accommodation for block offset in curved walls with setback.

FIG. 7 shows the tail block 18 which can have a male tongue 50 formed on each end to provide optional lateral attachment to the blocks, and with a female groove 52 centrally defined on each face according to the configuration of the face block 24. The grooves 52 can be oriented back-to-back and spaced apart by a solid web 66 of block material to provide adequate strength.

The tongues 50 and grooves 52 can be similarly tapered along their vertical lengths so that each dovetail joint is secured against excess motion and slippage by the tongue 50 being wedged into the groove.

FIGS. 8 and 9 show a second embodiment of the adjustable connector. This embodiment comprises a subassembly 78 comprising an inner tube 80 that is slidably insertable into an outer tube 82 in a telescoping manner. The overall length of subassembly 78 can be adjustable. In this embodiment, a locking pin 84, extending radially outward from the outer surface of the inner tube 80 can be provided. An elongated, longitudinally extending alignment channel 86 can be formed on one side of the outer tube 82 to accommodate the locking pin 84 and allow for insertion of the inner tube into the outer tube. The inner and outer tubes can be positioned into a locked configuration by rotating either tube to insert the locking pin 84 into one of several locking channels 88 extending perpendicularly from the alignment channel 86. A male tongue 50 can be provided on the distal end of each tube 80, 82 for insertion into corresponding grooves in blocks 18, 24. The male tongues 50 desirably are positioned such that rotating the tubes into the locked configuration to position the pin 84 into a selected channel 88 correctly orients the male tongue for insertion into a female groove 52 as described herein. FIG. 10 shows the locked configuration of the nested tube subassembly 78 in cross section.

In alternative embodiments, the locking pin 84 can extend radially inward from the inner surface of the outer tube 82. The alignment channel 86 and the locking channels 88 can be formed on the outer surface of the inner tube 80. The inner and outer tubes can be positioned into a locked configuration by rotating either tube to insert the locking pin 84 into one of several locking channels 88 extending perpendicularly from the alignment channel 86.

Another embodiment is shown in FIGS. 14 and 15. In this embodiment, the adjustable connector 68 can be provided with radially extending pins 110 at each end and the rear face of the face block 24 and the front face of the tail block 18 can be formed with respective openings 114, 116. Opening 114 is sized to receive the forward end portion of the connector 68 and a corresponding pin 110, while opening 116 is sized to receive the rear end portion of the connector 68 and a corresponding pin 110. Opening 114 is in communication with a laterally extending slot 112 that is sized to receive a corresponding pin 110. Similarly, opening 116 is in communication with a laterally extending slot 118 that is sized to receive a corresponding pin 110. To assemble the connector and the blocks, as best shown in FIG. 15, the end portions of the connector 68 are first inserted into openings 114, 116 with the pins 110 in a vertically upright position, and then the connector is rotated to rotate the pins 110 into the slots 112, 118, thereby “locking” the connector 68 to the face and tail blocks 24, 18.

In other alternative embodiments, the adjustable connector can comprise any construction configured to interconnect a face and tail block and to adjust the spacing therebetween. For example, the adjustable connector can comprise a first elongated connection member and a second elongated connection member. A first end portion of the first connection member is adapted to be connected to the face block and a second end portion of the second connection member is adapted to be connected to the tail block. The first and second connection members have second end portions that are adapted to be connected to each other at various locations to vary the spacing between the face and tail blocks. For example, the second end portions of each connection member can be formed with a plurality of longitudinally spaced openings adapted to receive a pin or bolt to connect the second end portions to each other at selected locations. The connection members can comprise flat, plate-like members, tubular members, I-shaped members, C-shaped members, or various other shapes.

In another embodiment, a spring-loaded locking pin similar to pin 84 of FIG. 9 can be provided on the outer wall of an inner tube 70. The spring-loaded pin extends radially outwardly from the inner tube and can be sized to extend through a plurality of alignment holes 74 (FIG.3) formed in an outer tube. In other alternative embodiments, the locking pin can be provided on the outer tube of the adjustable connector and the alignment channel or alignment holes can be formed in the inner tube.

In addition, the face and tail blocks 24, 18 can be constructed in various shapes and sizes. For example, the face and tail blocks can be square, rectangular, trapezoidal, diamond-shaped, or various combinations thereof.

In another embodiment, a block subassembly 10 can comprise a face block 24, a tail block 18, and a connector of fixed-length extending between and connecting the face block to the tail block. The connector can be formed from materials that are less expensive than concrete, and in some embodiments, can be fabricated to have a selected length to suit the needs of a particular application. In one example, the connector can comprise a piece of rebar or pipe having plates welded at its ends. The plates are sized to be inserted into the openings 52 in the blocks 24, 18. The openings 52 can be appropriately sized and shaped to complement and readily accept the shape of the plates of the connector.

Block assemblies having such a fixed-length connector can be used for a selected number of courses at the base of the wall where the depth of the wall is greatest and adjustable connectors can be used for courses above the base where the depth of the wall can be reduced.

FIG. 11 shows an embodiment of the lowermost course of a retaining wall formed from block subassemblies 10. In this embodiment, the connector 68 of each subassembly in the lowermost course can be provided with a downwardly projecting anchor, or projection, 100. The anchor 100 can be connected to the outer tube 72 by any suitable technique or mechanism (e.g., by welding or mechanical fasteners). The anchor 100 can be, for example, a piece of rebar or a tubular member (e.g., metal or plastic pipe). The anchor 100 extends downwardly into a trench 102 formed underneath the lowermost course of blocks between the face block 24 and the tail block 18.

After the lowermost course of side-by-side block assemblies 10 is formed over the trench 102, the trench can be filled with concrete to form a concrete footing 104 that extends upwardly into the voids between adjacent block subassemblies 10. The anchor 100 helps anchor each block subassembly to the concrete footing 104. The concrete footing 104 is effective to increase the sliding resistance of the wall. This allows the wall to be constructed with a smaller base width than would normally be required, which minimizes excavation and provides more space in the embankment behind the wall, such as for placement of utility easements or other structures. Additional details about forming a retaining wall with the footing 104 can be found in co-pending U.S. application Ser. No. 10/591,736, which is the national stage of PCT Application No. PCT/US2005/008744 (published as WO2005/100700), which is incorporated herein by reference. The block assemblies 10 used to form the remaining courses of the wall need not be provided with anchors 100 connected to the connectors 68.

In other alternative embodiments, the anchor 100 can be connected to the inner tube 70. Similarly, in other alternative embodiments, the connector 68 of each subassembly in the lowermost course could be a fixed-length connector having an anchor 100.

FIG. 12 shows a perspective view of an embodiment of a block subassembly utilizing pivotable connector elements that allow adjustment of the angle between the connector 68 and one or both of the face and tail blocks. In this embodiment, the adjustable connector 68 comprises a pivotable connector 90 coupled to each of the inner and outer tubes 70, 72. Each pivotable connector 90 can comprise a male dovetail connector element 92 and upper and lower ears 94 extending from the connector element 92. The ears 94 have vertical holes 96 sized to receive a pivot pin 64 and are vertically spaced to receive a respective end portion 98 of a tube 70, 72. Each end portion 98 also has vertical hole 106 sized to receive a corresponding pivot pin 64. The vertical holes 96 and 106 can be aligned and the pivot pin 64 inserted through the holes to pivotably connect the adjustable connector 68 to the pivotable connector 90. As further shown in the exemplary embodiment in FIG. 12, the adjustable connector 68 can be attached to the face block 24 and the tail block 18 by sliding the connector elements 92 vertically into the grooves 52 in the face and tail blocks.

As best shown in FIG. 13, the connector 68 can be pivoted in a horizontal plane relative to the face block 24 and/or the tail block 18 (as indicated by double-headed arrow in order to vary the angle θ between the connector 68 and the rear face 28 of the face block 24 and/or the angle α between the connector 68 and the front face 38 of the tail block 18. In addition, the face block 24 and/or the tail block 18 can be pivoted relative to the connector 68 so that the rear face 28 of the face block is not parallel to the front face 38 of the tail block. Advantageously, the adjustability of connector 68 relative to the face and tail block provides greater flexibility when constructing retaining walls. For example, when forming concave walls, a tail block can be pivoted relative to the respective face block of the same subassembly to position the tail block closer to a tail block of an adjacent subassembly in order to support a tail block of the course above. In addition, the use of a connector 68 that is pivotable at least with respect to the face block 24 enables construction of a convex retaining wall having a smaller radius of curvature than would normally be possible.

In view of the many possible embodiments to which the principles of the disclosed invention may be applied, it should be recognized that the illustrated embodiments are only preferred examples of the invention and should not be taken as limiting the scope of the invention. It should be apparent to those skilled in the art that the illustrated embodiments may be modified without departing from the principles described. Rather, the scope of the invention is defined by the following claims. I therefore claim as my invention all that comes within the scope and spirit of these claims.

Claims

1. A subassembly for constructing a retaining wall comprising:

a first block;

a second block spaced from the first block, the first and second block defining a space therebetween for receiving backfill material when constructing the wall; and

an adjustable connector extending between and connected to the first and second blocks, the adjustable connector configured to have an adjustable length to adjust the spacing between the first and second blocks.

2. The subassembly of claim 1, wherein the adjustable connector comprises an inner tube and an outer tube, the inner tube being telescopically slidable into and out of the outer tube to adjust the length of the adjustable connector.

3. The subassembly of claim 2, wherein one of the inner and outer tubes has at least one alignment hole and the other of the inner and outer tubes has a plurality of alignment holes, and

the subassembly further comprises a pin that can be inserted into the at least one alignment hole and a selected one of the plurality of alignment holes to restrict longitudinal movement of the tubes relative to each other.

4. The subassembly of claim 2, wherein the inner tube has an outer surface having a locking pin extending radially outward from the outer surface, and

the outer tube comprises an elongated longitudinally extending alignment channel on one side and a plurality of longitudinally spaced locking channels extending perpendicularly from and connected to the alignment channel, the alignment channel being configured to accommodate the locking pin and allow insertion of the inner tube into the outer tube, such that the inner and outer tubes can be positioned into a locked configuration by rotating either tube to insert the locking pin into a selected one of the plurality of locking channels.

5. The subassembly of claim 2, wherein the outer tube has an inner surface having a locking pin extending radially inward from the inner surface, and

the inner tube comprises an elongated longitudinally extending alignment channel on one side and a plurality of longitudinally spaced locking channels extending perpendicularly from and connected to the alignment channel, the alignment channel being configured to accommodate the locking pin and allow insertion of the inner tube into the outer tube, such that the inner and outer tubes can be positioned into a locked configuration by rotating either tube to insert the locking pin into a selected one of the plurality of locking channels.

6. The subassembly of claim 1, wherein the adjustable connector comprises a first elongated connection member and a second elongated connection member, and

the first and second elongated connection members are adapted to be connected to each other at a plurality of locations to vary the spacing between the first and second blocks.

7. The subassembly of claim 6, wherein one of the first and second connection members has at least one alignment hole and the other of the first and second connection members has a plurality of alignment holes, and

the subassembly further comprises a pin that can be inserted into the at least one alignment hole and a selected one of the plurality of alignment holes to restrict longitudinal movement of the connection members relative to each other.

8. The subassembly of claim 1, wherein the adjustable connector is configured to be pivotably connected to at least one of the first and second blocks, such that the adjustable connector can be pivoted, in a horizontal plane, to vary the angle between the connector and the block to which it is pivotably connected.

9. The subassembly of claim 1, wherein the first block comprises a rear face, the second block comprises a front face and a rear face and the adjustable connector comprises a first end portion and a second end portion, and

wherein the first end portion of the adjustable connector can be connected to the rear face of the first block and the second end portion of the adjustable connector can be connected to the front face of the second block.

10. The subassembly of claim 9, wherein each of the first and second end portions of the adjustable connector comprises a dovetail element for interlocking with complementary dovetail elements on the first and second blocks.

11. The subassembly of claim 9, wherein each of the first and second end portions of the adjustable connector comprises a male connecting element,

the rear face of the first block comprises an opening sized to receive the male connecting element of the first end portion of the adjustable connector, and

the front face of the second block comprises an opening sized to receive the male connecting element of the second end portion of the adjustable connector.

12. The subassembly of claim 9, wherein each of the first and second end portions of the adjustable connector comprises a radially extending pin,

the rear face of the first block comprises a slot complementarily sized to interlock with the radially extending pin of the first end portion of the adjustable connector, and

the front face of the second block comprises a slot complementarily sized to interlock with the radially extending pin of the second end portion of the adjustable connector.

13. The subassembly of claim 9, wherein each of the first and second end portions of the adjustable connector comprises a pivotable dovetail connector element, and

the rear face of the first block and the front face of the second block comprise complementary dovetail connector elements, for interlocking with the pivotable dovetail connector elements on the adjustable connector, the pivotable dovetail connector elements allowing the first and second blocks to be pivoted relative to the adjustable connector.

14. The subassembly of claim 13, wherein the pivotable dovetail connector element of each of the first and second end portions of the adjustable connector comprises a male dovetail connector element and a pivot pin pivotably connecting the dovetail connector element to the adjustable connector.

15. A building block system for building a retaining wall comprising:

a plurality of face blocks each having a rear face;

a plurality of adjustable connectors each having a first end portion and a second end portion, each adjustable connector being configured to have an adjustable length between its first and second end portions; and

a plurality of tail blocks each having a front face and a rear face,

wherein the blocks and adjustable connectors may be assembled to form block assemblies each having an adjustable connector connected at its first end portion to the rear face of a face block, the adjustable connector extending rearwardly from the rear face of the face block, with the second end portion of the adjustable connector connected to the front face of a tail block.

16. The system of claim 15, wherein additional adjustable connectors and tail blocks can be attached to extend rearwardly from the rear face of a tail block to form elongated block assemblies of variable selectable lengths.

17. A retaining wall comprising:

at least first and second vertically-stacked courses comprising a plurality of block subassemblies placed side-by-side in each course,

wherein each block subassembly comprises a face block having a front surface exposed in a face of the wall, a tail block positioned behind and spaced from the face block, and an adjustable connector extending between and connected to the face and tail blocks, the adjustable connector configured to have an adjustable length to adjust the spacing between the face and tail blocks.

18. The retaining wall of claim 17, wherein the plurality of block subassemblies are placed side-by-side such that a pair of adjacent block assemblies define a chamber therebetween, and

the chamber contains backfill material.

19. The retaining wall of claim 17, wherein the first course comprises the lowermost course of the wall and a trench extends underneath the first course, wherein one or more of the adjustable connectors in the first course comprise anchors projecting downwardly into the trench and being anchored to a concrete footing in the trench.

20. The retaining wall of claim 17, wherein the length of the adjustable connectors in the second course is smaller than the length of the adjustable connectors in the first course.

21. A method of constructing a retaining wall, comprising forming at least first and second vertically-stacked courses comprising a plurality of block assemblies,

at least some of the block assemblies in at least one course each comprising a face block, a tail block, and an adjustable connector that is adjustable in length to adjust the spacing between the face and tail blocks.

22. The method of claim 21, wherein the act of forming the first and second courses comprises:

adjusting the length of an adjustable connector;

connecting a first end of the adjustable connector to a respective face block; and

connecting a second end of the adjustable connector to a respective tail block.

23. The method of claim 21, wherein the act of forming the first and second courses comprises:

placing the block assemblies side-by-side in each course, such that each pair of adjacent block assemblies defines a chamber therebetween; and

filling the chamber with backfill material.

24. The method of claim 21, wherein the first course comprises the lowermost course of the wall, a trench extends underneath the first course, and building the first course comprises:

positioning the block assemblies, each having an adjustable connector comprising an anchor, such that the anchors project downwardly into the trench; and

filling the trench with concrete to fix the anchors to the concrete.

25. A subassembly for constructing a retaining wall comprising:

a first block;

a second block spaced from the first block; and

a connector comprising an elongated body having first and second opposite end portions, the first end portion being connected to the first block and the second end portion being connected to the second block, the connector being pivotable relative to at least the first block to permit adjustment of the angle between the connector and the first block.

26. The subassembly of claim 25, wherein the connector is configured to have an adjustable length to adjust the spacing between the first and second blocks.

27. The subassembly of claim 25, wherein the first end portion of the connector is pivotable relative to the first block at a pivot pin.

28. The subassembly of claim 25, wherein the connector is pivotably connected to the first and second blocks.

29. The subassembly of claim 25, wherein the first block has an opening and the first end portion of the connector comprises a male connector element adapted to be received in the opening of the first block, the male connector element being pivotably connected to the remaining portion of the connector.