Patent Publication Number: US-6213689-B1

Title: Construction unit for a retaining wall and a method for constructing the retaining wall

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a construction member adapted for constructing a retaining wall to keep a bank of earth from sliding or water from flooding. More particularly, the present invention relates to an assembly type construction member as a construction unit composed of a U-shape concrete panel and a concrete shelf plate installed in the rear side of the U-shape panel. Further, the present invention relates to a method for constructing a retaining wall by making use of a plurality of the construction unit. 
     2. Prior Art 
     Conventionally, concrete blocks have been commonly used in the construction of low height or small scale retaining wall, but in the case of great scale retaining wall construction, reinforced concrete wall have been built up by pouring concrete into wall-form at its own construction site. 
     However, such conventional reinforced concrete wall construction require a relatively wide bottom space for its foundation, thereby resulting in disadvantages such as long construction period, higher cost, and inefficient work. In addition to these disadvantages, since conventional reinforced concrete wall is rigid, this wall can not absorb or disperse the vibration energy and impact force caused by earth quake. 
     SUMMARY OF THE INVENTION 
     It is therefore a primary object of the present invention to overcome the above described disadvantages, that is, to provide an improved construction unit to construct a retaining wall which is improved in a bottom space, a construction period, and a construction cost. 
     Another object of the present invention is to provide an improved construction unit to construct a retaining wall which can withstand earth quake. 
     Further object of the present invention is to provide an improved construction unit to construct a retaining wall with a drainage structure. 
     Still further object of the present invention is to provide a method for constructing the above described retaining wall by making use of the improved construction unit. 
     In order to accomplish the above objects, the present invention provides a construction unit which can be vertically piled and horizontally arranged one by one to construct a retaining wall on a foundation. The construction unit is composed of a U-shape concrete panel having at least one drain, at least two I-shape concrete panels each of which is connected to the rear end of the U-shape panel, and at least one concrete shelf plate both ends of which are received by shelf receiving recesses formed in the inner surfaces of the U-shape panel and the I-shape panels. 
     The U-shape panel further includes a vertical engagement means to engage with the vertically piled U-shape panels, and connection members to connect to the I-shape panels. This vertical engagement means includes an upper hole formed in the top surface of the lower piled U-shape panel and a lower hole formed in the bottom surface of the upper piled U-shape panel, and a steel bar installed in the upper and lower holes. 
     The shelf plate is inclined downward at about 20° with respect to the horizontal plane. 
     The connection members are made of steel belt integrally formed in the rear ends of the U-shape panel and the front and rear ends of the I-shape panel, and are mechanically engaged through commonly used bolt and nut. 
     The drain is formed in a slit shape along the lower edge of the U-shape panel. 
     The U-shape panels and the I-shape panels are assembled to build up a retaining wall inclined rearward at about 10° with respect to the vertical plane. 
     According to another aspect of the present invention, a method for constructing a retaining wall by making use of the above described construction unit comprises following working steps for; 
     (1) forming a reinforced concrete foundation; 
     (2) placing a predetermined number of U-shape panels side by side on the foundation to make the first step face, which U-shape panel has at least one drain; 
     (3) placing two I-shape panels at the rear end of each the U-shape panel; 
     (4) mechanically connecting the rear end of the U-shape panel to the front end of the I-shape panel through a connection member; 
     (5) installing a shelf plate within shelf receiving recesses formed in the inside surfaces of the U-shape panel and I-shape panel so that the shelf plate is inclined downward at about 20° with respect to the horizontal face; 
     (6) arranging vertical reinforcing rods and horizontal reinforcing rods in the cavity like space defined between two construction units composed of the U-shape panel and I-shape panels; 
     (7) inserting a steel bar into the upper hole formed in the top surface of the first step U-shape panel; 
     (8) piling a second step U-shape panel on the first step panel with inserting the steel bar into the lower hole formed in the bottom surface of the second step panel; 
     (9) repeating the former working steps (2) to (8) up to the top step; and 
     (10) filling concrete into each of the cavity defined between the horizontally adjacent panels, and packing crushed stones into the inner space defined by the U-shape panel and two I-shape panels. 
     Thus constructed retaining wall is preferably inclined rearward at 10° with respect to the vertical plane. Since the construction unit according to the present invention is a self-standing structure, the retaining wall can be constructed upright in response to construction situation. 
    
    
     These and other objects and many of the attendant advantages of the present invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings. 
     BRIEF DESCRIPTION OF THE DRAWING 
     FIG. 1 is a vertically sectional view showing a retaining wall constructed by making use of a plurality of the construction unit according to the present invention; 
     FIG. 2 is an enlarged exploded perspective view showing one typical preferred embodiment of the construction unit according to the present invention. 
     FIG. 3 is a cross sectional view taken along the line A—A in FIG. 1; 
     FIG. 4 is a perspective view showing a front face of the retaining wall constructed according to the present invention; and 
     FIG. 5 is a perspective view showing a rear side structure of the retaining wall constructed according to the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     One preferred embodiment of the construction unit according to the present invention and a typical example of the retaining wall constructed by making use of a plurality of the construction unit and one preferred embodiment of method of the present invention will be explained in detail with referring to the accompanying drawings FIG. 1 to FIG.  5 . 
     First, FIG. 1 is a vertical section showing an overall of the retaining wall which is substantially composed of a foundation  1  containing reinforcing rods  11 , and a plurality of concrete construction unit  5  vertically piled on the foundation  1 . 
     One preferred embodiment of the construction unit  5  is shown in detail in FIG.  2 . The construction unit  5  is composed of a U-shape concrete panel  2  having a drain  3 , at least two I-shape concrete panels  7  each of which is connected to the rear end of the U-shape panel  2 , and at least one concrete shelf plate  4  both ends of which are received by shelf receiving recesses  8  formed in the inner surfaces of the U-shape panel  2  and the I-shape panel  7 . 
     The U-shape panel  2  further includes a vertical engagement means to engage with the vertically piled U-shape panels  2 , and connection members to connect to the I-shape panels  7 . The vertical engagement means contains upper and lower holes  6   a  and  6   b  to receive a steel bar installed between these holes. This upper and lower holes  6   a  and  6   b  may be formed in a through hole. The U-shape panel  2  includes at least two vertical engagement means at both ends, preferably four. 
     From each rear end of the U-shape panel  2 , the connection member  8   a  is protruded rearward to connect to corresponding connection member  8   b  protruded forward from the front end of the I-shape panel  7 . In this preferred embodiment, these connection members  8   a  and  8   b  are made of steel belt integrally formed in the U-shape panel  2  and the I-shape panel  7 , and are mechanically engaged through commonly used bolt and nut, not shown in the drawings. The rear end of the I-shape panel  7  is also provided with such connection members to connect further I-shape panels as required. Although FIG. 2 shows that each end of the U-shape panel  2  is provided with four connection members  8   a , it is possible to increase or decrease in accordance with construction conditions. 
     The present invention further provides a preferred embodiment of method for constructing a retaining wall by making use of the above described construction unit. As shown in FIG. 1, seven U-shape panels  2  are piled up to form the retaining wall having a height about 3 m. The piled U-shape panels  2  are inclined rearward at 10° with respect to the vertical plane. The shelf plate  4  is inclined downward at 20° with respect to the horizontal plane. Accordingly, the shelf receiving recess  8  is so designed to make the front end of the shelf plate  4  to be inclined downward at 30° as shown in FIG.  2 . 
     First, the predetermined number of the U-shape panels  2  are placed side by side on the foundation  1  to make the first step face. Two I-shape panels  7  are placed at the rear end of each the U-shape panel  2 , and mechanically connected with each other through the connection members  8   a  and  8   b . One or more I-shape panels  7  may be further connected to the first connected I-shape panel  7  as required. The shelf plate  4  is received by a facing pair of the shelf receiving recesses  8 . 
     FIG. 3 is the cross-sectional view taken along the line A—A in FIG. 1, to show the plan view of the construction unit composed of the U-shape panel  2 , the I-shape panels  7 , and the shelf plates  4 . In the cavity defined between two construction units  5 , vertical reinforcing rods  10  and horizontal reinforcing rods  12  are arranged. 
     In order to build the second step, a steel bar is inserted into the upper hole  6   a  and an additional U-shape panel  7  is piled on the first step panel  7  with inserting the steel bar into the lower hole  6   b  of the second step panel  7 . 
     The above described process is repeated up to the top step. At each step, the horizontal and vertical reinforcing rods  12  and  10  are mechanically connected in conventional manner. The top end of the vertical reinforcing rod  10  is bent to reinforce the berm  13  of top surface. 
     After assembling the U-shape panels and the I-shape panels, and incorporating the reinforcing rods between these panels as shown in FIG.  4  and FIG. 5, the cavity  9  defined between the horizontally adjacent panels are filled with concrete, and then the inner space defined by the U-shape panel  2  and two I-shape panels is stuffed with crushed stone. 
     It is desirable to arrange the drain  3  on a level of the front end of the shelf plate  4  to increase draining efficiency. 
     As given explanation above, since the retaining wall constructed by making use of the construction unit according to the present invention is inclined rearward 10° with respect to the vertical plane, the bottom width required to make the foundation can be decreased rather than conventional construction methods. When the foundation is formed by full scale ground work, required ground durability can be decreased. When the foundation is formed by piles, the required number of piles can be reduced. This results in economical merits. 
     Since the retaining wall is constructed by connecting the construction units at substantially 1 m pitch, thus constructed retaining wall has a tenacious structure capable of absorbing vibration energy caused by earth quake and this retaining wall can be free from expansion joints conventionally used to improve vibration absorbing ability. In addition to this structure, this retaining wall includes a lot of the shelf plates inclined at 20° with respect to the horizontal face, which will act as reinforcing members to withstand the impact caused by earth quake. 
     Since the retaining wall according to the present invention has a lot of drains and the inner spaces of the wall are stuffed with crushed stones, rain water can be smoothly drained from the rear side of the retaining wall. This effect ensures that the retaining wall can keep a bank of earth from sliding by rain water. 
     The U-shape panel is provided with the connection holes to engage the upper or lower U-shape panel in combination with the steel bar, so that the stability and assemble work of the retaining wall can be improved. 
     The construction unit according to the present invention can be assembled in a self-standing manner which does not require an inclined wall construction. 
     As many apparently widely different embodiments of this invention may be made without departing from the spirit and scope, it is to be understood that the invention is not limited to the specific embodiments thereof except as defined in the appended claims.