Abstract:
A method of building an underground structure using concrete columns to be vertically installed at corners and at positions between the corners and concrete panels to be filled between adjacent concrete columns. The method comprises the steps of determining positions for the concrete columns, digging a trench for a guide composed of outer and inner frames, drilling holes for the columns, the holes being deeper than a level where the concrete panels are placed, installing the columns into the holes and setting with concrete, removing the outer frame of the guide, deepening the trench, fitting concrete panels between the columns, installing a reinforcing metal beam using concrete on the columns and panels to prevent inward buckling, and removing the inner frame of the guide after the concrete on the reinforcing beam has set.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to a method of building an underground structure, and more particularly to a method of building an underground structure composed of vertical corner columns and vertical concrete columns provided between the corner columns, and concrete panels fitted between adjacent columns. The concrete panels are moved downward while digging the ground under them. 
     2. Description of the Related Art 
     In the related art, an underground structure is usually built in the following manner. Concrete columns are vertically installed in a dug area of a ground at positions corresponding to corners and intermediate portions of the underground structure to be built. Concrete panels are fitted between the columns while digging the ground under them to a predetermined depth. The side edges of the concrete panels are joined to the columns using bolts or the like. The bottom of the underground structure is made by applying concrete to a space defined by the concrete panels. (Refer to Japanese Patent No. 282954.) 
     SUMMARY OF THE INVENTION 
     According to the invention, there is provided a method of building an underground structure constructed with concrete columns vertically installed at corners and at positions the corners and concrete panels fitted between adjacent concrete columns. The method comprises the steps of: determining positions for installing the concrete columns, and digging a trench for burying a guide used for the concrete columns; drilling holes for burying the concrete columns in the trench, the holes being deeper than a level where the concrete panels are placed; assembling the guide, the guide being composed of outer and inner frames, and guide members for burying the concrete columns; installing the columns in the trenches along the guide, and filling concrete in the holes to fix the concrete columns in the holes; removing the outer frame of the guide; deepening the trench, digging an area for the underground structure, and moving the concrete panels down; installing a reinforcing beam on the concrete columns and the concrete panels to prevent the concrete panels from projecting inward due to soil pressure; and removing the inner frame of the guide after the reinforcing beam is hardened. 
     This method may further include the steps of providing a bottom of the underground structure by applying concrete on the area defined by the concrete panels, and filling a water sealant in spaces between the concrete panels and the columns, installing frames in spaces between ends of adjacent concrete panels, and filling mortar in the spaces between the concrete panels. 
     The method is applicable to providing an underground parking lot with a mechanical two-story lift. 
     The reinforcing beam extending atop the columns and panels are effective in joining them without using bolts or the like, and in preventing the panels from projecting inward due to ground pressure. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 shows the steps of building an underground structure according to the invention. 
     FIG. 2 shows how a trench is dug. 
     FIG. 3 shows how holes for installing columns are drilled. 
     FIG. 4 shows how a guide is installed in the trench. 
     FIG. 5 shows how columns are installed and fixed. 
     FIG. 6 shows removal of an outer frame of the guide. 
     FIG. 7 shows installation of panels and digging a space defined by the panels. 
     FIG. 8 shows how a bottom of the underground structure is made. 
     FIG. 9 shows construction of a reinforcing beam. 
     FIG. 10 shows removal of an inner frame of the guide shown in FIG.  1 . 
     FIG. 11 is a top plan view of the guide. 
     FIG. 12 is a side view of the guide. 
     FIG. 13 is a partially enlarged top plan view of the guide. 
     FIG. 14 is a cross sectional view of the guide taken along line A—A in FIG.  13 . 
     FIG. 15 is a perspective view of a part of one of corners of the guide. 
     FIG. 16 is a perspective view of an intermediate part of the guide. 
     FIG. 17 is a top plan view of one example of a column provided between corners. 
     FIG. 18 is a front view of the column of FIG. 17 
     FIG. 19 is a perspective view of the column of FIG.  17 . 
     FIG. 20 is a cross section of the column taken along line D—D in FIG.  19 . 
     FIG. 21 is a top plan view of a corner column. 
     FIG. 22 is a front view of the corner column. 
     FIG. 23 is a right side cross section of the corner column. 
     FIG. 24 is a perspective view of the corner column. 
     FIG. 25 is a cross section of the corner column taken along line H—H in FIG.  24 . 
     FIG. 26 is a top plan view of one example of a panel used for the invention. 
     FIG. 27 is a front view of the panel. 
     FIG. 28 is a cross section of the panel taken along line E—E in FIG.  27 . 
     FIG. 29 shows the state in which panels are joined to the corner column. 
     FIG. 30 is a longitudinal section taken along line F—F in FIG.  29 . 
     FIG. 31 is a top plan view showing the state in which panels are joined to the column provided between the corners. 
     FIG. 32 is a front view showing the state in which panels are joined to the column provided between the corners. 
     FIG. 33 is a top plan view of an underground structure built according to the method of the invention. 
     FIG. 34 is a longitudinal cross section of the center part of the underground structure. 
     FIG. 35 is a lateral cross section of the center part of the underground structure. 
     FIG. 36 is a cross section of a strut used for the method of the invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The method of the invention is executed in the sequence shown in FIG.  1 . 
     (1) Preparation 
     First of all, spaces for storing heavy machines and installation materials are prepared at a site where an underground structure such as a cellar or a parking lot is to be built. Positions of columns and a trench N are determined. A guide R for burying the columns is placed in the trench N. 
     (2) Digging the Trench N 
     The trench N is dug as shown in FIG. 2 using a back hoe B. The trench N is 1.0 m deep, and wide enough to place the guide R (shown in FIG. 11) therein, as will be described later. 
     (3) Drilling Holes for Installing Columns 
     Referring to FIG. 3, positions where holes  13  are drilled in the trench N are precisely measured. An auger G is used for drilling the holes  13 . The holes  13  are larger than the columns, and are deep compared with a bottom part of the underground structure defined by concrete panels  80  (which will be described later with reference to FIG. 27) and shown by a broken line in FIG.  7 . If a sloping area is drilled, a casing will be used in order to prevent walls of the holes from falling down. 
     (4) Placing the Guide R 
     A guide installing area is readjusted in order to precisely position the guide R as predetermined, as shown in FIG.  4 . 
     Referring to FIGS. 11 to  16 , the guide R has a double structure, and includes upper and lower guide parts  11 G and  11   g  which are vertically joined. The upper guide part  11 G is constituted by outer and inner frames  11 A and  11 B which are laterally joined. The outer frame  11 A includes four H-beams  11   a,    12   a,    13   a  and  14   a  assembled as predetermined. The inner frame  11 B includes H-beams  11   b,    12   b,    13   b  and  14   b,  and is smaller than the outer frame  11   a  by a depth of columns  50  which are provided between corners, and corner columns  60 . These columns will be described later with reference to FIGS. 19 and 24. The lower guide part  11   g  is identical to the upper guide part  11 G, and is constituted by H-beams  11   ag,    12   ag,    13   ag,    14   ag,    11   bg,    12   bg,    13   bg  and  14   bg  (H-beams  12   ag,    13   ag,    11   bg,    12   bg  and  13   bg  are not shown in the foregoing drawings). The upper and lower guide parts  11 G and  11   g  are joined using channel irons  21  to  40 . 
     Referring to FIGS. 13 and 15, the guide R is joined at corners thereof as follows. At one corner of the upper guide  11 G, the H-beams  11   a  and  14   a  of the outer frame  11 A are joined to the channel irons  21  and  40  using bolts  41   a  and  42   a  and nuts  41   b  and  42   b.  The H-beams  11   b  and  14   b  of the inner frame  11 B are joined to the channel irons  21  and  40  using bolts  43   a  and  44   a  and nuts  43   b  and  44   b.  The upper and lower guide parts  11 G and  11   g  are identically assembled, are assigned the like reference numerals, and will not be described here. 
     In the upper guide part  11 G, the outer and inner frames  11 A and  11 B are joined between the columns at a part C shown in FIG. 11, as a typical example. Referring to FIGS. 13 and 16, the H-beam  11   a  of the outer frame  11 A is joined to the channel irons  22  and  23  using bolts  45   a  and  46   a  and nuts  45   b  and  46   b.  The H-beam  11   b  of the inner frame  11 B is joined to the channel irons  22  and  23  using bolts  47   a  and  48   a  and nuts  47   b  and  48   b.  The upper and lower guide parts  11 G and  11   g  are identical, are assigned the like reference numerals, and will not be described here. 
     When the outer and inner frames  11 A and  11 B are assembled as described above, the guide R has hollow spaces RW (shown in FIGS. 13 and 15) at its four corners RA, RB, RC and RD. The corner columns  60  are fitted into the hollow spaces RW as described later. Further, the guide R is provided with guide holes RY (shown in FIGS. 13 and 16) at positions RE, RF, RG, RH, RI and RJ between the corners. The columns  50  are fitted into the guide holes RY as described later. In FIGS. 15 and 16, the foregoing bolts and nuts are depicted by dotted lines. 
     Referring to FIGS. 13 and 15, angle irons RK, RL, RM and RN are provided in the respective hollow spaces RW of the guide R in order to guide the corner columns  60  therein, and are welded to the guide R. A channel iron RQ is provided in the space RY at the part C in order to guide the column  50 , and is bolted to the guide R. 
     (5) Installing and Fixing Columns 
     The corner columns  60  (shown in FIG. 14) and columns  50  are guided into the spaces RW and RY (shown in FIG. 13) and fitted into the holes  13  using a crane of a wrecker truck K. The distances between the columns are accurately measured. Then, concrete is applied into the holes  13  to a level below the level shown by a broken line in FIG. 5 so that the columns  50  and  60  are fixedly supported in the holes  13 . In this case, a short hose should be used in order to prevent concrete materials from being separated from one another. The guide R is used to reliably install the columns  60  and  50 . 
     Each column  50  is substantially rectangular, and has a trapezoidal portion on its inner surface along its length as shown in FIGS. 17 to  20 . The trapezoidal portion has a flat top  51  for receiving joints  54  to be described later. The column  50  is made of concrete and includes reinforcing rods having shapes of a rectangle and a corrugation, and a plurality of embedded inserts IS in the shape of a fork. Eye bolts IB are detachably screwed into the inserts IS when the column  50  is suspended by the crane. 
     A plurality of rectangular joints  54  having side edges  54   a  are attached on the top  51  of the trapezoidal portion of the column  50 , using bolts  56  which are detachably attached to the inserts IS. The column  50  has a pair of grooves M along the opposite sides of the trapezoidal portion in order to receive a sealant. 
     Each corner column  60  is substantially in the shape of an L as shown in FIGS. 21 to  25 , and has a part  62  in the shape of a step. The part  62  is engaged along its length with a plurality of joints  70  in the shape of a cross. Specifically, legs  71  and  72  of the joints  70  are fixed to the part  62  using bolts  65  having inserts. Each joint  70  has its legs  71  and  72  and portions  73  and  74  welded at its center. The corner column  60  includes reinforcing steel  67  having a shape of the L, and a plurality of inserts IS embedded at the top thereof, and is detachably engaged with eye bolts IB. The inserts IS have forked portions. 
     (6) Removal of the Outer Frame 
     When the columns  50  are fixed in the hole  13  after concrete is hardened, the outer frame  11 A and channel irons  21  to  40  are removed from the trench N by releasing the bolts  43   a,    44   a,    47   a  and  48   a,  so that the panels  80  can be installed without any problem. Refer to FIG.  11 . However, the inner frame  11 B is left as it is since it is used as a support. 
     (7) Installation of the Panels and Digging an Area Defined by the Panels 
     The panels  80  are suspended by the crane of the wrecker truck K, and installed by matching the joints  81  and  82  (shown in FIGS. 29 and 31) thereof with the joints  54  and  70  of the columns. The space defined by the panels  80  is dug using the back hoe B. The panels  80  are moved down into the trench N which is manually dug at the bottom. 
     Each panel  80  is installed between the corner column  60  and the column  50  as shown in FIGS. 26 to  28 , and includes an L-shaped joint  81  fixed at its one side edge  80   a  using bolts  85  having inserts. A free end  81   a  of the joint  81  faces to the exterior of the panel  80 , and has a length in order to be fitted between the joint  54  and an inner surface  53  of the column  50  (see FIG.  31 ). 
     The panel  80  also has an L-shaped joint  82  fixed to the other side edges  80   b  using a bolt  85  having the insert. A free end  82   a  of this L-shaped joint  82  faces inward to the panel  80 , and has a length in order to be fitted between the parts  71  and  72  of the joint  70  for the column  50  and the surface  63  of the corner column  60  (see FIG.  29 ). The panel  80  comes into contact with the corner column  60  via its side edge  80   b  and with the column  50  via its side edge  80   a.  A plurality of inserts IS having forked ends are embedded in the upper part of the panel  80 , and are detachably engaged with eye bolts IB used for suspending the panel  80  using the crane. 
     The panel  80  is made of concrete and includes reinforcing steel  86  in the shape of a lattice. The panel  80  is usually installed between the corner column  60  and the column  50 . However, when they are installed between the columns  50 , they have joints facing outward. 
     Referring to FIGS. 29 and 30, the panel  80  is installed between the parts  73  and  74  of the joints  70  and the surfaces  63  of the corner column  60  in such that the side edge  80   b  and joint  82  of the panel  80  slide on the joints  72  and  73 . Further, the panel  80  is installed between the part  54   a  of the joint  54  and the surfaces  53  of the column  50  such that the side edge  80   a  and joint  81  of the panel  80  slide on the joints  54  of the column  50 , as shown in FIGS. 31 and 32. 
     As shown in FIGS. 33 to  35 , the underground structure is completed when the panels  80  are installed between the adjacent corner columns  60  and the columns  50 . In this case, the underground structure is used to make an underground parking lot with three juxtaposed parking spaces and two-story mechanical lift. 
     (8) Making a Bottom Floor 
     Referring to FIG. 8, the area defined by the panels  80  is readjusted. A base material K is uniformly applied to the readjusted space, which is then rammed. Anchors are hooked to the inserts embedded in the panels  80  in order to install reinforcing members. Then, concrete is applied onto the reinforcing members, thereby forming a bottom floor W (shown in FIG. 9) using a chute S. The concrete is finished using a metal trowel. 
     (9) Filling a Sealant and Mortar 
     A sealant such as foam rubber is filled into the gaps between the panels  80  and columns  60  and  50 , i.e. especially in the grooves M so that the underground structure is protected against leaking water. Further, a frame  90  made of plywood or the like is inserted into the gaps between the side edges  80   a  and  80   b  of adjacent panels  80 , and mortar is filled in the foregoing gaps (refer to FIGS.  29  and  31 ). 
     (10) Providing a Reinforcing Beam 
     A base material of a reinforcing beam  95  is uniformly applied on the upper parts O of the columns  60  and  50  and panels  80 . The eye bolts provided atop the columns  60  and  50  and panels  80  and used for suspending these members are replaced with reinforcing eye bolts. A reinforcing metal is placed on the base material, a frame for the reinforcing beam  95  is placed, and concrete is applied into the frame, thereby forming the reinforcing beam  95  (refer to FIG.  10 ). 
     If the underground structure is used to make a parking lot with three or more juxtaposed parking spaces and two-story lift, a plurality of struts  96  are provided across the upper parts of the columns  50  (see FIG. 33) in order to prevent the columns  50  from projecting inward due to ground pressure. The strut  96  is made of concrete and includes a rectangular reinforcing steel  96   a.    
     Referring to FIGS. 33 to  35 , the reinforcing beam  95  extends along the upper edges of the panels  80  and columns  60  and  50 , and has a predetermined width in order to prevent the panels  80  from projecting inward due to the ground pressure. In these drawing figures, “AN” denotes anchor bolts. 
     (11) Removing the Inner Frame 
     After the reinforcing beam  95  is hardened, the inner frame  11 B will be removed from the panels  80 , and columns  60  and  50 . In this state, the underground structure is completed according to the method of the invention. 
     In FIGS. 6,  7  and  9 , “Z” denotes temporary members. 
     Referring to FIGS. 33 and 35, the underground structure, i.e. three juxtaposed parking lots with the two-story mechanical lit, is composed of the columns  50  and  60 , panels  80 , and bottom W, and reinforcing beam  95 . In these figures, reference numeral  100  denotes a drain. 
     Although the invention has been described with reference to the preferred embodiment, it should be noted that the invention may be modified without departing from the spirit and scope thereof. For instance, the method of the invention is applicable to building a parking lot with two to 14 juxtaposed parking spaces with two-story mechanical lift.