UNDERGROUND-STRUCTURE CONSTRUCTION METHOD

Abstract

An underground-structure construction method of arranging an underground structure by causing drilling apparatuses engaged with a concrete-made closed-shaped bottom frame to travel in a reciprocating manner to drill a just-underground of a bottom part of the underground structure, discharging to an earth surface excavated earth and sand of an internal ground, and extending a building frame of an upper part of the underground structure includes: open-cutting a ground to form a larger-sized mortar-shaped working hole; forming a closed-shaped horizontal reference area in an edge ground; arranging a bottom frame on the horizontal reference area; building a first stage building frame on the bottom frame; and backfilling, with backfill soil, an annular-shaped outer space of inner and outer spaces as a result of dividing the working hole, the drilling apparatuses being caused to uniformly drill, from the horizontal reference area as a drilling initiation plane, the just-underground of the bottom part.

Claims

1. An underground-structure construction method of arranging underground an underground structure by: causing a plurality of drilling apparatuses, which are reciprocatably engaged with a bottom frame of closed shape made of concrete of the underground structure, to travel in a reciprocating manner so as to drill a just-underground of a bottom part of the underground structure; discharging, to an earth surface, excavated earth and sand of an internal ground on an internal side of the underground structure; and extending a building frame of an upper part of the underground structure, the underground-structure construction method comprising the steps of: open-cutting a ground so as to form a mortar-shaped working hole larger in size than the underground structure; forming a horizontal reference area of closed shape in an edge ground of a bottom part of the working hole; arranging a bottom frame on the horizontal reference area in the working hole so as to form the bottom frame into a closed shape; building a first stage building frame of the underground structure on the bottom frame in the working hole; and backfilling, with backfill soil, an annular-shaped outer space out of inner and outer spaces as a result of dividing the working hole at the underground structure, wherein the plurality of drilling apparatuses are caused to uniformly drill, from the horizontal reference area as a drilling initiation plane, the just-underground of the bottom part of the underground structure.

2. The underground-structure construction method according to claim 1 wherein the bottom frame has a continuous lower flange formed thereon, and a self-weight of the underground structure is supported, through an entire lower surface of the lower flange, by the just-underground of the bottom part of the underground structure.

3. The underground-structure construction method according to claim 1 wherein in parallel with causing the plurality of drilling apparatuses engaged with the bottom frame to uniformly drill the just-underground of the bottom part of the underground structure, the internal ground on the internal side of the underground structure is excavated so that excavated earth of the internal ground is discharged to the earth surface.

4. The underground-structure construction method according to claim 1 wherein the plurality of drilling apparatuses engaged with the bottom frame are caused to perform a width-expansion drilling beyond a width of the building frame of the underground structure, so that the underground structure is allowed to sink while a space is formed for insulation between a hole wall as a result of the width-expansion drilling and an outer wall surface of the underground structure.

5. The underground-structure construction method according to claim 2 wherein the plurality of drilling apparatuses engaged with the bottom frame are caused to perform a width-expansion drilling beyond a width of the building frame of the underground structure, so that the underground structure is allowed to sink while a space is formed for insulation between a hole wall as a result of the width-expansion drilling and an outer wall surface of the underground structure.

6. The underground-structure construction method according to claim 3 wherein the plurality of drilling apparatuses engaged with the bottom frame are caused to perform a width-expansion drilling beyond a width of the building frame of the underground structure, so that the underground structure is allowed to sink while a space is formed for insulation between a hole wall as a result of the width-expansion drilling and an outer wall surface of the underground structure.

7. The underground-structure construction method according to claim 1 wherein each of the plurality of drilling apparatuses includes: a self-propellable travelling body engaged with the bottom frame; and a rotary cutter arranged in the travelling body rotatably around a vertical axis, so that each of the plurality of drilling apparatuses drills the just-underground of the bottom part of the underground structure through the rotary cutter's rotation and travel along the bottom frame.

8. The underground-structure construction method according to claim 2 wherein each of the plurality of drilling apparatuses includes: a self-propellable travelling body engaged with the bottom frame; and a rotary cutter arranged in the travelling body rotatably around a vertical axis, so that each of the plurality of drilling apparatuses drills the just-underground of the bottom part of the underground structure through the rotary cutter's rotation and travel along the bottom frame.

9. The underground-structure construction method according to claim 3 wherein each of the plurality of drilling apparatuses includes: a self-propellable travelling body engaged with the bottom frame; and a rotary cutter arranged in the travelling body rotatably around a vertical axis, so that each of the plurality of drilling apparatuses drills the just-underground of the bottom part of the underground structure through the rotary cutter's rotation and travel along the bottom frame.

10. The underground-structure construction method according to claim 4 wherein each of the plurality of drilling apparatuses includes: a self-propellable travelling body engaged with the bottom frame; and a rotary cutter arranged in the travelling body rotatably around a vertical axis, so that each of the plurality of drilling apparatuses drills the just-underground of the bottom part of the underground structure through the rotary cutter's rotation and travel along the bottom frame.

11. The underground-structure construction method according to claim 5 wherein each of the plurality of drilling apparatuses includes: a self-propellable travelling body engaged with the bottom frame; and a rotary cutter arranged in the travelling body rotatably around a vertical axis, so that each of the plurality of drilling apparatuses drills the just-underground of the bottom part of the underground structure through the rotary cutter's rotation and travel along the bottom frame.

12. The underground-structure construction method according to claim 6 wherein each of the plurality of drilling apparatuses includes: a self-propellable travelling body engaged with the bottom frame; and a rotary cutter arranged in the travelling body rotatably around a vertical axis, so that each of the plurality of drilling apparatuses drills the just-underground of the bottom part of the underground structure through the rotary cutter's rotation and travel along the bottom frame.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0045] For more thorough understanding of the present invention and advantages thereof, the following descriptions should be read in conjunction with the accompanying drawings in which:

[0046] FIG. 1 depicts a longitudinally cross-sectional view showing an underground structure.

[0047] FIG. 2 depicts a longitudinally cross-sectional view showing the bottom part of the underground structure.

[0048] FIG. 3 depicts an explanatory view of a method with respect to: an open-cutting operation of a working hole shown in (a); an installation operation of the bottom frame and a construction operation of the underground structure shown in (b); and a backfilling operation of an annular space shown in (c).

[0049] FIG. 4 depicts an expanded view showing the installation operation of the bottom frame.

[0050] FIG. 5 depicts a cross-sectional view showing the bottom part of the underground structure obtained by placing concrete in the formwork.

[0051] FIG. 6 depicts a conventional underground-structure construction method.

DESCRIPTION OF EMBODIMENTS OF THE INVENTION

[0052] The following sections will describe the present invention in detail with reference to the drawings.

[0053] [1] Underground Structure

[0054] Description will be made with reference to FIGS. 1, 2. The underground structure 10 is a concrete-made box having a horizontal cross section having e.g. a rectangular shape, a polygonal shape, a circular shape, or an elliptical shape. The building frame thickness and its entire size are appropriately selected depending upon the application of the underground structure 10.

[0055] [1.1] Bottom Frame

[0056] The lower end of the underground structure 10 has the bottom frame 11. The underground structure 10 is supported to be abutted to the ground through the bottom frame 11.

[0057] In this example, a case will be described in which the bottom frame 11 is constituted by H-like steel obtained by connecting a pair of upper and lower flanges 12 and 13 by a web 14. However, another configuration also may be used in which the pair of upper and lower flanges 12 and 13 has therebetween connected two webs 14 with an interval thereamong.

[0058] The bottom frame 11 may have a continuous lower flange 13. Any contact surface structure may be used so long as the structure allows the underground structure 10's self-weight to be supported by the just-underground of the bottom part of the underground structure 10 through the entire lower face of the lower flange 13.

[0059] [1.2] Incidental Equipment of Bottom Frame

[0060] Description will be described with reference to FIGS. 2 and 4. The inner faces of the inner sides of the upper and lower flanges 12 and 13 have a pair of guide rails 15 opposed to each other to guide the drilling apparatus 30. At the center of the inner faces of the inner sides of the web 14, a reaction force receiver 16 such as a straight gear is continuously provided in order to obtain the self-propelled reaction force of the drilling apparatus 30.

[0061] [2] Drilling Apparatus

[0062] The drilling apparatus 30 for drilling the just-underground of the underground structure 10 may be a known apparatus.

[0063] The following section will describe the drilling apparatus 30 shown in FIG. 2. The drilling apparatus 30 is a self-propelled apparatus that has both of a function to scrape and drill the just-underground at the lower end of the underground structure 10 and a function to discharge the drilled soil to the inner side of the underground structure 10.

[0064] The drilling apparatus 30 includes a travelable travelling body 35 engaged with the guide rails 15 of the lower end 21 of the underground structure 10, a travel means for the travelling body 35, a rotary cutter 31 provided in the travelling body 35, and the rotation means for the rotary cutter 31.

[0065] [2.1] Travelling Body

[0066] The travelling body 35 is a horizontal stand that is anchored so as to be travelable to the bottom frame 11 while including therein the rotary cutter 31.

[0067] The travelling body 35 has a plurality of idling rollers 36 and can be engaged with the guide rails 15 through the idling rollers 36.

[0068] The travelling body 35 includes a driving source 32 such as a motor and a gear-like travel wheel 33.

[0069] The travel wheel 33 is engaged with the reaction force receiver 16 of the bottom frame 11. The driving source 32 provided in the travelling body 35 drives the travel wheel 33 to invert the forward and backward directions of the travel wheel 33, thereby self-propelling the drilling apparatus 30 along the bottom frame 11.

[0070] [2.2] Rotary Cutter

[0071] The rotary cutter 31 includes at least a rotation axis 31a penetrating the travelling body 35 in a longitudinal direction for axial support and a plate-like horizontal rotor 31b provided in the rotation axis. The lower face and tip end of the horizontal rotor 31b have a plurality of drilling bits.

[0072] The forward and backward movements of the rotary cutter 31 can be inverted by the rotation of the driving source 34 such as a motor provided in the travelling body 35.

[0073] By changing the drilling radius of the rotary cutter 31, the expansion drilling exceeding the building frame width of the underground structure 10 can be achieved.

[0074] [2.3] Operation Control of Drilling Apparatus

[0075] A plurality of the drilling apparatuses 30 can be controlled so as to be able to uniformly drill the just-underground at the bottom part of the underground structure 10.

[0076] The uniform drilling means a drilling operation to move the plurality of drilling apparatuses 30 so as to be able to maintain the favorable horizontality of the underground structure 10.

[0077] Specifically, when the underground structure 10 has an oblong planar shape, the respective drilling apparatuses 30 are allowed to operate so that the drilling apparatus 30 provided on the long side and the drilling apparatus 30 provided on the short side start the drilling operation at the same timing from the starting point position and reach a turning point at the same timing.

[0078] The respective drilling apparatuses 30 can be operated automatically or manually.

[0079] (Underground-Structure Construction Method)

[0080] Next, the following section will describe a method of constructing the underground structure 10.

[0081] [1] Open-Cut Operation and Formation of Reference Horizontal Plane

[0082] Description will be made with reference to (a) in FIG. 3. The ground 40 under which the underground structure 10 is planned to be sunk is open-cut to form a mortar-shaped working hole 41.

[0083] The working hole 41 is sized so that the lateral width L.sub.1 above the ground is larger than the lateral width L.sub.2 of the bottom part and the lateral width L.sub.2 of the bottom part of the working hole 41 is larger than the lateral width L.sub.3 of the underground structure 10.

[0084] The working hole 41 has a depth H that is sufficient to correspond to the height of about one span of the underground structure 10 (about 3 to 6 m).

[0085] When the working hole 41 is formed, a horizontal reference area 42 having a continuous closed shape is formed that is obtained by horizontally levelling the edge ground of the bottom part of the working hole 41.

[0086] The horizontal reference area 42 functions as a drilling initiation plane when the bottom frame 11 is placed and the underground structure 10 is sunk. Thus, it is very important that the horizontal reference area 42 is sufficiently compacted to have a high accuracy.

[0087] [2] Assembly of Bottom Frame

[0088] Description will be described with reference to (a) in FIG. 3 and FIG. 4. The hung steel material such as H steel is lowered into the working hole 41. Then, the bottom frame 11 is assembled to have a closed shape on the horizontal reference area 42.

[0089] When the bottom frame 11 is placed on the horizontal reference area 42, the bottom frame 11 is assembled while confirming the horizontal levels of the respective steel materials.

[0090] The bottom frame 11 can maintain the high horizontality by the continuous horizontal reference area 42 formed to have a high horizontal accuracy in advance over the entire length and the horizontal reference area 42 having a surface contact with the lower flange 13 to support the bottom frame 11 so that the weight of the bottom frame 11 is uniformly distributed.

[0091] [3] Assembly of Drilling Apparatus

[0092] Description will be made with reference to FIG. 2 and (b) in FIG. 3. In the working hole 41, a plurality of the drilling apparatuses 30 are assembled on the horizontally-installed bottom frame 11 with an interval thereamong.

[0093] The respective drilling apparatuses 30 are assembled to the inner side of the bottom frame 11.

[0094] [4] Construction of Underground Structure

[0095] With reference to (b) in FIG. 3 and FIG. 5, the following section will describe a step of constructing a part corresponding to one span of the underground structure 10 (height of about 5 to 6m). The reinforcing bar 50 is assembled on the upper flange 12 of the bottom frame 11 and a formwork 51 is assembled so as to face the reinforcing bar 50.

[0096] After the formwork 51 is assembled over the entire length of the bottom frame 11, the formwork 51 is uniformly filled with concrete 53 sent from a plurality of positions.

[0097] The placed concrete 53 increases the weight loaded to the bottom frame 11. However, the continuous lower flange 13 of the bottom frame 11 has a surface contact with the continuous horizontal reference area 42 to uniformly distribute the loaded weight. Therefore, the bottom frame 11 can maintain the high horizontality.

[0098] After the concrete 53 is cured, the formwork 51 is disassembled and removed.

[0099] Since the working hole 41 is formed to be larger than the outer shape of the underground structure 10, a series of operations can be smoothly and efficiently carried out, including an operation to assemble the reinforcing bar 50, an operation to assemble the formwork 51, and an operation to disassemble the formwork 51.

[0100] [5] Backfilling of Annular Space

[0101] As shown in (c) in FIG. 3, the space in working hole 41 is divided into two inner and outer spaces to sandwich the underground structure 10, forming the internal space 41a of the underground structure 10 and the outer annular space 41b of the underground structure 10.

[0102] Backfill soil 43 is placed on the entire area of the annular space 41b to backfill the interior until the backfilling reaches the earth surface level.

[0103] [6] Sinking of Underground Structure by Self-Weight

[0104] Description will be made with reference to FIG. 1. The operation to use a plurality of the drilling apparatuses 30 to drill the just-underground of the bottom rail 11 and the operation of drilling and the earth removal of the internal ground 43 of the underground structure 10 are carried out repeatedly, thereby sinking the underground structure 10 by its self-weight.

[0105] [6.1] Uniform Drilling by Drilling Apparatus

[0106] Each drilling apparatus 30 starts the uniform drilling of the continuous horizontal reference area 42 shown in FIG. 5 while repeating the reciprocation along bottom rail 11. The drilled earth and sand are discharged into the internal space 41a of the underground structure 10.

[0107] The plurality of the drilling apparatuses 30 uniformly drill the just-underground of the bottom part of the underground structure 10. Thus, the underground structure 10 is allowed to sink due to its self-weight while maintaining the favorable horizontality at the start of the sinking.

[0108] In the initial stage of the sinking, the earth pressure due to the backfill soil 43 acts on the outer peripheral surface of the underground structure 10. However, the weight of the underground structure 10 overwhelms the earth pressure, thus preventing the backfill soil 43 from hindering the underground structure 10 from sinking.

[0109] The backfill soil 43 abutted to the outer peripheral surface of the underground structure 10 is significantly effective to prevent the entire underground structure 10 from being laterally moved or being inclined during the initial stage of the sinking of the underground structure 10.

[0110] In other words, the backfill soil 43 significantly contributes to the sinking of the underground structure 10 while maintaining the high horizontality.

[0111] In the case of the conventional construction method, the space 44 formed between the expanded and drilled pore wall and the outer wall face of the underground structure 10 was filled with a fine grain aggregate for reducing the frictional resistance.

[0112] The drilling apparatus 30 drills the just-underground until the building frame width of the underground structure 10 is exceeded to thereby form the space 44 functioning as an insulating structure between the pore wall subjected to the expansion drilling and the outer wall face of the underground structure 10. Therefore, this construction method does not require the operation to fill the space 44 with the fine grain aggregate.

[0113] [6.2] Drilling of Internal Ground and Discharge of Earth and Sand

[0114] The internal ground 43 of the underground structure 10 is drilled using a known drilling apparatus.

[0115] In order to improve the earth removal of the drilling apparatus 30, the neighborhood of the underground structure 10 is drilled to form an annular groove along the underground structure 10. Specifically, when a drilling operation is performed by the drilling apparatus 30, the annular groove is desirably drilled in advance so that a groove bottom is positioned at a lower position than the just-underground of the bottom part of the underground structure 10.

[0116] The drilled earth and sand in the underground structure 10 is discharged onto the ground by a clam shell bucket 44 or a known earth removal means such as a conveyor delivery or a damped motor lorry.

[0117] [6.3] Extension of Underground Structure

[0118] In parallel with the sinking of the underground structure 10 or after the sinking of the underground structure 10, the building frame is additionally provided and extended to the upper part of the underground structure 10.

[0119] As required, a slab 17 is horizontally constructed in the underground structure 10.

[0120] The slab 17 also may be formed by providing an opening 17a at a part of the slab 17 to remove earth onto the ground through this opening 17a.

[0121] The slab 17 is used as the installation floor of the electric power facility 18 to supply power to the drilling apparatus 30.

[0122] [6.4] Removal of Drilling Apparatus

[0123] After the underground structure 10 is sunk to a predetermined depth, the drilling apparatus 30 is removed from the bottom frame 11. The removed drilling apparatus 30 is reused.

[0124] The underground structure 10 is used for various applications with a slab provided on the bottom part.

[0125] [7] Regarding Horizontality of Underground Structure

[0126] The extended building frame of the underground structure 10 causes an increase of the loaded weight on the bottom rail 11. However, according to the present invention, the underground structure 10 can be sunk while maintaining the horizontality of the underground structure 10 due to the following reasons.

[0127] A ratio of a region occupied by the drilling apparatus 30 to the entire length of the bottom rail 11 is very small. Therefore, the underground structure 10's self-weight is distributed and uniformly supported by the just-underground maintaining the horizontality over the entire length of the bottom rail 11.

[0128] Therefore, the underground structure 10's self-weight does not directly act on the drilling apparatus 30. The drilling apparatus 30 can efficiently drill the just-underground firmly compacted by the underground structure 10's self-weight.

[0129] As described above, according to this construction method, the underground structure 10 can be sunk while maintaining the high horizontality. This consequently can eliminate any of a high-cost subsidence control apparatus and a foundation pile for supporting this and a concrete foundation used in the conventional construction method, thus achieving a shorter construction period and a significantly-reduced construction cost.

TABLE-US-00001 (Reference Numerals) 10 Underground structure 11 Bottom frame 20 Subsidence control apparatus 30 Drilling apparatus 31 Rotary cutter 40 Ground 41 Working hole  41a Internal space  41b Annular space 42 Horizontal reference area