Abstract:
Mechanically stabilized retaining wall structures are comprised of a stabilized earth mass connected to a precast concrete panel facing wall. A lengthwise adjustable turnbuckle style connector assembly accommodates horizontal and vertical offsets in the connection points. An array of the connection assemblies comprise a three-dimensional space truss that accomodates wall movement horizontally and vertically with respect to the wall face as well as perpendicular to the wall.

Description:
FIELD OF THE INVENTION 
     This invention relates generally to stabilized earthen structures, and specifically relates to an adjustable turnbuckle style assembly for connecting precast concrete panels to a previously constructed wire face wall, which has been or may be subjected to foundation settlement. 
     BACKGROUND OF THE INVENTION 
     Retaining wall structures may be comprised of backfill or earth material with a facing of precast panels. Mechanically stabilized earth structures are generally described in a series of Vidal patents including U.S. Pat. Nos. 3,421,326, 3,686,873, 4,045,965, and 4,116,010. 
     Vidal disclosed that longitudinal, tensile members positioned within a granular, compacted mass of earth to thereby enhance the coherency of the particles that form the mass. The stabilized soil mass can then serve as a wall or embankment. This phenomenon of enhanced coherency is accomplished, at least in part, by frictional engagement of particles in the mass with the tensile members or tie strips extending through the mass. Often such stabilized earthen mass includes a facing made from precast concrete panels. 
     A variety of methods and apparatus are known for attaching the tensile members projecting from the stabilized earthen mass to the precast concrete panels. For example, U.S. Pat. No. 4,961,673, issued to Pagano, discloses a connector that attaches a mounting plate, extending from the back face of a panel to a tie strip extending from within the stabilized soil mass. The attachment is achieved by threading a bolt through the opening in both the tie strip and the mounting plate and securing the bolt with a nut. The Pagano arrangement permits little adjustability with regard to horizontal and vertical offsets of the panel connectors vis-à-vis the tiestrips when installed. 
     U.S. Pat. No. 5,971,669, issued to Crigler, discloses a connector that permits some horizontal and vertical adjustments at the attachment points of the precast concrete panels and the tensile strips of the mechanically stabilized earth structure. The Crigler connection has a two-part housing, i.e., there are two, separate female connectors that threadably receive the male turnbuckle through the open end of the housing. The connection attaches the wire mesh panels that define a face for the stabilized soil mass, to precast concrete facing panels. The attachment at the panel facing is made by means of an elongate member oriented substantially parallel to the ground level that passes through the aperture at the end of the first housing as well as apertures that extend from the face of the precast concrete panels. The apertures are lined up, and the elongate member is passed through the series of apertures to secure the connector. The connection at the precast concrete panel wall, however, allows movement in the longitudinal direction of the member between the apertures. 
     When constructing an earth retaining wall of the type described, the granular material, which is compacted for cooperation with the tensile members, may not fully consolidate to its final volume during the period of wall construction. For example, compacted earth may only consolidate approximately 90% of its expected bulk consolidation during the construction phase of such a retaining wall. Over time, the bulk form may therefore continue to consolidate and, as a result, differential settlement may occur between the soil mass and the precast panel facing. 
     Due not only to the difficulties inherent in predicting differential settlement, but also to general variations in construction tolerances, the connecting points between the precast concrete panels and a previously constructed wire face wall may not line up in directly opposing positions. In this event, some vertical and horizontal offset between the connecting points may necessarily result. 
     SUMMARY OF THE INVENTION 
     The present invention is a low-cost connector assembly that efficiently allows for significant differential settlement between precast concrete facing panels and the mechanically stabilized earth mass without transferring undue stress to the wall panels. The invention is an adjustable assembly that connects fixed points on the face of the precast concrete panels to the wire mesh wall that can accommodate significant offsets between connection points. The universal joint connections allow the connector assemblies to be rotated such that the connection points in the closest proximity can be linked. The invention provides a plurality of connectors where the ends are pivotally connected at fixed spaced pivot points to accommodate misalignment by forming angled rather than straight connections, which in combination defines a three-dimensional truss. The ends of each connector define a first array at the facing panels and a second array at the connection of the connector to the stabilized earth structure such as to a wire mesh facing. These and other objectives, advantages, and features of the invention will be set forth in the detailed description which follows. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     In the detailed description which follows, reference will be made to the drawing comprised of the following figures: 
     FIG. 1 is an elevation view of a mechanically stabilized earth mass connected to a panel wall by multiple connection assemblies. 
     FIG. 2 is a plan view of FIG.  1 . 
     FIG. 3 is a perspective view of the completed connector assembly incorporating the present invention with ladder-type tensile members used in the mechanically stabilized earth mass. 
     FIG. 4 is a perspective view of the completed alternative connector assembly incorporating the present invention with the connection at the panel face in a generally horizontal orientation. 
     FIG. 5 is a perspective view of the completed connector assembly incorporating the present invention with strip-type tensile members in the mechanically stabilized earth mass, and a connection at the panel face in the vertical orientation. 
     FIG. 6 is a perspective view of the completed connector assembly incorporating the present invention with the connection at the panel face in the horizontal orientation. 
     FIG. 7 is an elevation view of the connection to the mechanically stabilized earth mass. 
     FIG. 8 is a plan view of FIG.  7 . 
     FIG. 9 is a plan view of the slotted clip used in the connection to the mechanically stabilized earth mass. 
     FIG. 10 is an elevation view of the connector assembly. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The connector assembly of the present invention can be illustrated by describing the method of installation of the connector with reference to the drawing FIGS. 1,  2 ,  3 ,  4 ,  5 ,  6 ,  7 ,  8 ,  9 , and  10 . Like numbers thus designate like parts in the respective drawings. 
     FIGS. 1 and 2 illustrate a completed mechanically stabilized earth mass  400 . The wire facing units  200  form the face of the mechanically stabilized earth mass  400 . Tensile reinforcement  300 ,  301  is connected to the wire facing units  200  and passes through the earth mass. A panel wall  125  is connected to the wire facing units  200  by a plurality of connector assemblies  150 . An array of connector assemblies  150  at various angled directions define in combination a three dimensional space truss  500  that resists wall movement horizontally, vertically, as well as inward or outward from the face of the mechanically stabilized earth mass. 
     FIG. 3 illustrates the configuration and appearance of a connector assembly  150  in relation to a panel wall  125  and the wire facing units  200  of a mechanically stabilized earth mass  400 . The panel wall  125  is preferably comprised of multiple precast concrete forms or panels  126 . 
     The connector assembly, also referred to as a turnbuckle assembly,  150  is comprised of a threaded rod  100  that is threadably received by coil nuts  111 A,  111 B at each end which are connected respectively to coil loops  110 A,  110 B. The coil nuts  111 A,  111 B are typically connected to the coil loops  110 A,  110 B offsite and prior to construction by welding. The connector assembly  150  is also shown in FIG.  10 . The coil loops, or longitudinal loops,  111 A,  111 B and coil nuts, or threaded sockets,  110 A,  110 B form connection adjustment mechanisms, also referred to as turnbuckle brackets,  112 A,  112 B that permit the connector assembly  150  to be lengthwise adjustable by turning the threaded rod  100  (or loops  110 A,  110 B) in a turnbuckle fashion thus simultaneously retracting or extending coil loops  110 A,  110 B from the midpoint between the loops  110 A,  110 B. 
     The first coil loop  110 A is attached to the precast concrete panel  125  at a generally fixed connection point. The precast concrete panel  125  has a slotted clip, or linkage,  105  protruding from the back face  120  of the wall  125 . The slotted clip  105  is also referred to as a linkage. The slotted clip  105  is a curved member with the crown  105 A protruding from the back face  120  of the wall panel  125 , and the legs  127 A,  127 B extending into the wall panel  125 . The slotted clip  105  has apertures  107 A,  107 B in the legs  127 A,  127 B of the slotted clip  105  that receive an anchor rod  106 . The anchor rod  106  distributes the tensile stress exerted by the connector assembly and prevents a pull-out type failure. The anchor rod  106  is inserted into the apertures  107 A,  107 B of the slotted clip  105  and cast-in-place within the precast concrete panel  125  such that it is an integral part of the panel  125 . 
     The crown  105 A of the slotted clip  105  has a notch  108  cut out at the midpoint to receive the coil loop  110 A of the connector assembly  150  at this connection point. The notch  108  is of sufficient size to allow the connector assembly  150  to be pivotally rotated from side to side about the longitudinal axis of a bolt  102 . As the slotted clip  105  is cast in concrete, the pivot points are generally fixed at spaced intervals. Thus, after inserting the coil loop  110 A into the notch  108  cut out of the slotted clip  105 , and aligning the aperture of the coil loop  110 A with the apertures created by the crown  105 A of the slotted clip  105  that extend beyond the back face of the panel  125 , a pin, typically a bolt,  102  is inserted vertically through the aperture  110 A and the apertures created by the crown  105 A to affix the connection. The bolt  102  is secured with a nut  104  and washers  103 A,  103 B on each end to prevent the bolt  102  from passing through the apertures created by the crown  105 A of the slotted clip  105 . When the pin  102  is secured, a univeral joint mechanism  140  is formed that allows the connector assembly  150  to pivotally move with respect to the panel wall  125 . 
     The second coil loop  110 B is attached to the wire facing or mesh  200  of the mechanically stabilized earth mass  400 , also called the retained backfill. A second slotted clip, or linkage,  201  is connected to the wire facing  200  where a ladder-type tensile member  300  extends rearward into retained backfill. The slotted clip  201  is curved with apertures  205 A,  205 B in the legs  227 A,  227 B of slotted clip  201 . FIG. 9 shows the aperture  205 A in greater detail. The slotted clip  201  is connected to the ladder member  300  by means of a bolt connection. The end of the ladder member  300  has a connector section or plate  301 , a flat tab section with an aperture in the center. The connector section or plate  301  is typically connected to the ladder member  300  offsite and prior to construction by means of welding. The slotted clip  201  is placed over a rod member  202 A of the wire facing unit  200  such that the rod member is within the throat of the slotted clip  201 . The apertures  205 A,  205 B of the slotted clip  201  are aligned with the aperture  301 A of the connector section  301  such that a pin, typically a bolt,  212  can be passed through the apertures  205 A,  205 B,  301 A to affix clip  201  to plate  301 . The bolt  212  is secured with nut  211  and washers  210 A,  210 B positioned on the outside of the slotted clip  201 . When the pin  212  is secured, a universal joint mechanism  240  is formed that allows the connector assembly to pivotally move with respect to the wire mesh facing  200 . FIGS. 7,  8 , and  9  show the universal joint mechanism in detail. 
     The crown  201 A of the slotted clip  201  has a notch  206  cut out at the midpoint to receive the coil loop  110 B of the connector assembly  150 . The notch  206  is of sufficient size to allow the connector assembly  150  to be pivotally rotated. After inserting the coil loop  110 B into the notch  206  cut out of the slotted clip  201 , and aligning the aperture of the coil loop  110 B with the apertures created by the crown  201 A of the slotted clip  201 , a connector rod  202  is inserted horizontally through the apertures created by the crown of the slotted clip  201  to affix the connection. The connection of the connector assembly  150  to the connection adjustment mechanisms  112 A,  112 B forms an adjustable connector construction. A slotted clip  201  and coil loop  110 B assembly is typically provided at the end of each ladder member  300  prior to construction of the precast panel wall  125  so that the threaded rod  100  of the connector assembly  150  can be rotated to locate the nearest coil loop  110 B after the connector assembly  150  has been attached to the back face  120  of the panel  125 . 
     Either end of the connector assembly  150  can be connected first, and then rotated freely to find the nearest connection point for the opposite end of the assembly  150 . For example, the connector assembly  150  can be initially attached to the wire facing unit  200  and then freely rotated to locate the nearest slotted clip  105  embedded in a precast concrete panel  125 . Alternatively, the connector assembly  150  can be initially attached to a slotted clip  105  embedded in the concrete panel  125  and then rotated to locate the nearest coil loop  110 B for making the connection. Threading the rod  100  into the coil nut  111 B completes the connection and fixes the panel  125  from inward or outward movement. 
     FIG. 4 illustrates the configuration and appearance of the connector assembly in relation to the panel wall  125  and the wire facing units  200  of the mechanically stabilized earth mass. The configuration and appearance of the connector assembly in FIG. 4 differs from that presented in FIG. 3 only in that the orientation of the slotted clip  105  and anchor rod  106  in the precast concrete panel are rotated such that the bolt  102  is inserted horizontally through the apertures to affix the connection. 
     FIG. 5 illustrates the configuration and appearance of the connector assembly in relation to the panel wall  125  and the wire facing units  200  of the mechanically stabilized earth mass. The configuration and appearance of the connector assembly in FIG. 5 differs from that presented in FIG. 3 in that the slotted clip  201  is connected to a tensile strip  310  by means of the bolted connection. As mentioned previously, various forms of tensile reinforcement are disclosed in the prior art, which are typically selected based on the backfill material. Note, however, that the tensile reinforcement may simply be selected based upon the availability of construction materials. 
     FIG. 6 illustrates the configuration and appearance of the connector assembly in relation to the panel wall  125  and the wire facing units  200  of the mechanically stabilized earth mass. The configuration and appearance of the connector assembly in FIG. 6 differs from that presented in FIG. 5 only in that the orientation of the slotted clip  105  and anchor rod  106  in the precast concrete panel are rotated such that the bolt  102  is inserted horizontally through the apertures to affix the connection. 
     FIG. 7 illustrates the universal joint mechanism  240  at the face of the wire mesh wall  200 . 
     Thus, having described the foregoing invention, one skilled in the art would be enabled to practice the invention and know of the best mode for such practice contemplated by the inventor herein. Also one having such skill would readily understand many variations and changes that could be made in the above system without departing from the scope and content thereof.