Patent Publication Number: US-2007110522-A1

Title: Retaining wall constructed using sandbags

Description:
TECHNICAL FIELD  
      The invention pertains to retaining walls made of sandbags.  
     BACKGROUND OF THE INVENTION  
      Retaining walls are used in a wide variety of civil engineering and landscaping applications, for example to support slopes and embankments for highways, support noise barriers, prevent erosion along waterways, etc. Retaining walls are commonly made having a support face structure made of interconnecting blocks with soil or other fill material placed and compacted in back of the wall, and generally with sheets of geogrid laid in the fill at various levels, extending back from the wall and attached to it.  
      International Patent Publication No. WO 00/61880 published Oct. 19, 2000 discloses a system of building retaining walls from sandbags which uses interconnecting members to attach the sandbags in adjacent courses to each other so as to stabilize and strengthen the sandbag wall structure, permitting the construction of permanent retaining wall structures. The interconnecting members are plates having projections on both sides thereof that protrude into horizontally and vertically adjacent sandbags. Optionally, sheets of geogrid may be attached to the interconnecting members to extend at selected courses into the fill material supported by the sandbags in order to help stabilize the fill and anchor the sandbag structure to the fill.  
      The cost and labor involved in the construction of sandbag retaining walls could be reduced if the wall could be made without the need to excavate in back of the wall face and to use backfill and geogrid. Such walls would be particularly useful if they could be utilized for the retention of steep slopes.  
     SUMMARY OF THE INVENTION  
      The invention provides a retaining wall structure having a wall face constructed of sandbags connected together by means of interconnecting members, with the sandbags in the courses of the wall laid side to side along their lengths so as to form a relatively deep wall face with a higher density of sandbags than would be used in a conventional sandbag wall.  
      The retaining wall structure is made using sandbags which have a length that is greater than their width. Vertically-adjacent courses of sandbags form the wall face, the sandbags within the courses being positioned adjacent to one another along their lengths such that one end of each sandbag forms part of an inner side of the wall face adjacent to the slope being supported and the opposite end of the sandbag forms a part of the outer side of the wall face. Interconnecting members are positioned between the vertically-adjacent courses to connect the sandbags to sandbags of vertically-adjacent courses. The interconnecting members along a given course of sandbags alternate between a position that is proximate to the inner side of the wall face and a position that is proximate to the outer side of the wall face.  
      The invention also provides a retaining wall structure in which the sandbags in at least one course of sandbags are positioned adjacent to one another side to side along their lengths, as described above, and one or more vertically adjacent courses comprises sandbags that are positioned adjacent to one another end to end, along their widths. Interconnecting members are positioned between the vertically adjacent courses to connect the sandbags of each course to the vertically adjacent courses. The interconnecting members along a given such course alternate between a position proximate to the inner side of the wall face and a position proximate to its outer side.  
      The wall structures of the invention are strong and stable and useful for retaining steep slopes. They do not require the use of geogrid.  
      The term “sandbag” as used herein means a bag containing any “fill material.” “Fill material” means any material that is suitable for use in bags in the construction of walls, including sand, soil, gravel, dry mix concrete (which hardens after wetting and curing) and mixtures thereof, including fill material with seeds for vegetation. For further clarity, the term “sandbag” is not limited to a bag in which the fill material is sand. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a cross-sectional view through a retaining wall according to the invention.  
       FIG. 2  is a top perspective view of a course of sandbags of the retaining wall with interconnecting members in their positions.  
       FIG. 3  is an enlarged cross-sectional view through the wall showing an interconnecting member in position between vertically adjacent courses.  
       FIG. 4  is a sectional view on the line  4 - 4  of  FIG. 3 .  
       FIG. 5  is a perspective view of a portion of a retaining wall according to second embodiment of the invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      Referring to  FIGS. 1 and 2 , a retaining wall structure  10  according to the invention is constructed on ground  12  and has a wall face  14  supporting slope  20 . The wall face comprises a plurality of courses  18  of sandbags  16 . The wall structure is preferably laid generally horizontally, though it may follow the contour of the ground as required. The courses  18  of the wall face are laid one above the other conforming to the slope  20 , which may vary from a gradual slope to a substantially vertical one, depending on the particular application. The sandbags of vertically-adjacent courses are preferably positioned in a staggered arrangement, i.e. so that each sandbag in a course rests on two horizontally-adjacent sandbags in the vertically-adjacent lower course, as seen in  FIG. 4 . The courses  18  of the wall face are “vertically-adjacent” in the sense that they are generally one above the other, so as to form a wall having a height, though not necessarily, or typically, forming a vertical wall, as a wall having some slope is generally preferred. The vertically-adjacent courses are therefore typically offset somewhat relative to each other, as seen in  FIG. 1 .  
      Sandbags  16  have a width W and length L, the length being greater than the width, and opposed ends  11 ,  13  and opposed sides  15 ,  17 . The sandbag is typically closed at one end  11  or  13  with a suitable tie (not shown) to hold in the fill material therein.  
      The sandbags are preferably made of a geotextile material that is durable and permits water to flow into and through the bags, and seedlings to grow out, while retaining fine soil particles within the bag. The material of the bags should not be biodegradable, for durability of the wall. The sandbags may contain plant seeds so that a plant cover can be grown on the exterior of the wall face.  
      Interconnecting members  22  are used in the construction of the retaining wall  10 . Interconnecting member  22  comprises a plate  24 , preferably rectangular and planar in shape, with a plurality of projections  26 ,  27  extending from the upper and the lower sides respectively of the plate. Projections  26 ,  27  are sufficiently strong and pointed to protrude into the sandbags. Interconnecting member  22  is preferably made of plastics or aluminum or other non-corrodible material. Preferred dimensions of the interconnecting member are about 286 millimeters in length, 100 millimeters in width and 42 millimeters in height (including the projections). Generally, the interconnecting members may be of the types described in International Publication No. WO 00/61880 dated Oct. 19, 2000.  
      The sandbags in each course  18  are positioned at about a right angle to the slope that is being reinforced. They are laid adjacent to one another along their lengths, i.e. with sides  15 ,  17  of adjacent sandbags abutting each other. The outer side  30  of the wall face  14  is accordingly formed of ends  11  of the sandbags, and the inner side  32  of the wall face  14  is formed of the opposed ends  13  of the sandbags. The wall face is accordingly deeper and has a higher density of sandbags than a sandbag wall constructed with the sandbags laid end to end, in which the thickness of the wall face is defined by the width of the bags rather than by their lengths.  
      When a course of sandbags is placed on top of a lower course and on interconnecting members  22  positioned thereon, the projections  26  on the upper side of the plate protrude into the sandbags in the upper course, and the weight of such sandbags presses the interconnecting members so that the projections  27  on their lower side protrude fully into the sandbags in the lower course. The projections  26 ,  27  can be configured to fully penetrate the sandbags, or, preferably, to simply indent them. In either case, the projections are considered to “protrude” into the sandbags.  
      Interconnecting members  22  are of a size and configuration such that, when a member  22  is placed over a portion of two abutting sandbags within a course, some of the projections  27  on the lower side of the plate will protrude into each of the two horizontally abutting sandbags, connecting them together, and when a sandbag is placed on top of such plate, i.e. in laying a vertically-adjacent upper course, projections  26  on the upper side of the member will protrude into that sandbag, attaching the upper sandbag to the two lower sandbags. Thus, the interconnecting members attach both horizontally and vertically adjacent sandbags at the same time.  
      The interconnecting members  22  are preferably positioned in a staggered manner on each course, as best seen in  FIG. 3 . Along each course, every second interconnecting member is positioned proximate to the outer side  30  of the wall face, i.e. between the outer side  30  and the lateral center line of the sandbags, and the alternating interconnecting members are positioned proximate to the inner side  32  of the wall face, i.e. between the inner side  32  and the lateral center line of the sandbags. This arrangement increases the strength and stability of the wall face.  
      In another embodiment of the retaining wall of the invention, a course  18  of sandbags that are laid side to side along their lengths is used in conjunction with other courses of sandbags that are laid end to end. Referring to  FIG. 5 , retaining wall  40  comprises a course  18  of sandbags  16  laid side to side along their lengths between a vertically-adjacent lower course  42  and a vertically adjacent upper course  44 , both of which comprise sandbags  16  laid end to end. The wall  40  includes additional courses of sandbags laid in the orientation of course  18  or the orientation of courses  42 ,  44 , to a height required for a particular application. In retaining wall  40 , the inner side of the wall face is not even, as the sandbags in course  18  extend further into the slope  20  than the sandbags of courses  42 ,  44 , so some fill may be used in back of courses  42 ,  44 . Interconnecting members are positioned along each course to attach together the horizontally-adjacent sandbags within each course and the vertically-adjacent sandbags of the adjacent courses. The interconnecting members are positioned in a staggered arrangement similar to the one described above, with every second interconnecting member positioned proximate to the outer side  46  of the wall face and alternating ones positioned proximate to the inner side  48 . It will be understood that the latter interconnecting members are positioned proximate to the inner side of the sandbags of courses  42 ,  44  so as to fully engage the sandbags that are positioned end to end.  
      While exemplary embodiments have been discussed above, those skilled in the art will recognize that various modifications thereof may be made. For example, the interconnecting members can be of any shape and configuration that is suitable for connecting sandbags in a particular application. It is intended that the following appended claims are interpreted to include all such modifications as are within their true scope.