JP2012097416A - Construction method of underground structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To secure workability while setting the width dimension of the outer peripheral part of an underground structure constructed in advance to the absolute minimum and making the outer peripheral part of the underground structure constructed in advance appropriately function as earth retaining timbering.SOLUTION: A construction method of an underground structure includes: a step of constructing an earth retaining wall 1; a step of excavating the inner side of the earth retaining wall 1; a step of constructing a skeleton 11a of the outer peripheral part of the underground structure along the inner surface of the earth retaining wall 1; a step of excavating the inner side of the earth retaining wall 1 and executing bedding; and a step of constructing the remaining skeleton of the underground structure on the excavated inner side of the earth retaining wall 1. In the construction method, data indicating the relation between the maximum displacement ratio of the earth retaining wall 1 and the width dimension W of the outer peripheral part in the case of constructing the entire underground structure and in the case of constructing the outer peripheral part of the underground structure is prepared for each soil type, the width dimension W for turning the ratio to 1 or to the ratio of the allowable displacement of the earth retaining wall 1 is read on the basis of the data corresponding to the soil type of a construction site, and the skeleton 11a of the outer peripheral part of the underground structure is constructed by the width dimension W.

Description

  The present invention relates to a construction method for an underground structure.

  Conventionally, as a construction method of an underground structure, for example, as described in Patent Document 1 below, a structure of an outer peripheral portion of the underground structure is constructed in advance along the inner surface of the retaining wall, and this structure is used as a retaining structure for retaining the mountain. The construction method to be used has been proposed. More specifically, first, a retaining wall is constructed along the outer edge of the excavation area. Next, after excavating the inside of the retaining wall to expose the inner surface of the retaining wall, a frame of the outer peripheral portion of the underground structure is constructed along the inner surface of the retaining wall. Next, the inside of the retaining wall is excavated and floored, and then the remaining casing of the underground structure is built inside the excavated retaining wall and integrally with the outer peripheral casing.

  According to the above construction method, the support work for supporting the retaining wall can be omitted, and the temporary facilities can be reduced. In addition, there are few restrictions on application conditions, and the present invention can be widely applied to various conditions. Furthermore, the degree of freedom of space inside the retaining wall can be improved, and workability is improved by carrying out excavation residual soil and carrying in / out of building construction materials through the opening inside the outer peripheral frame. be able to.

JP 2010-1701 A

  However, in the conventional underground structure construction method described above, there is a problem that the horizontal displacement generated in the retaining wall cannot be sufficiently suppressed if the width dimension of the outer peripheral portion of the underground structure to be constructed in advance is small. On the other hand, if the width dimension of the outer peripheral portion of the underground structure to be constructed in advance is too large, there is a problem that the opening area inside the outer casing of the outer peripheral portion is reduced and the workability is lowered. Therefore, in the conventional construction method of the underground structure described above, the outer peripheral portion of the underground structure to be constructed in advance so that the workability can be ensured while the outer peripheral portion of the underground structure to be constructed in advance is functioning properly as a retaining support. However, there is no conventional method for determining the width dimension.

  In the present invention, the above-described conventional problems are considered, and the width dimension of the outer peripheral portion of the underground structure to be constructed in advance can be set to the minimum necessary. It aims at providing the construction method of an underground structure which can ensure workability, making it function properly as a mountain retaining work.

  The construction method of an underground structure according to the present invention includes a step of constructing a retaining wall along an outer edge of an excavation region, a step of excavating the inside of the retaining wall to expose an inner surface of the retaining wall, and an underground structure A step of constructing a frame of the outer peripheral portion along the inner surface of the retaining wall, a step of excavating the inside of the retaining wall and flooring, and a case of the outer peripheral portion inside the excavated retaining wall And a step of constructing the remaining frame of the underground structure integrally with the above, in a construction method of the underground structure, with respect to the maximum displacement of the retaining wall when the frame of the underground structure is constructed over the entire plane The data indicating the relationship between the ratio of the maximum displacement of the retaining wall and the width of the outer periphery of the underground structure when the outer structure of the outer structure of the underground structure is constructed are a plurality of assumed ground types. Create each In addition, based on the data according to the ground type of the construction site, the width dimension at which the ratio is 1 is read, and the frame of the outer peripheral portion of the underground structure is constructed with the width dimension. .

  Due to such features, the retaining wall can be displaced to the same extent as the case where the frame of the underground structure is constructed over the entire plane, while keeping the width dimension of the outer peripheral part of the previously constructed underground structure to the minimum necessary. The width dimension of the outer peripheral portion of the underground structure is determined so as to be suppressed.

  The construction method of the underground structure according to the present invention includes a step of constructing a retaining wall along the outer edge of the excavation region, a step of excavating the inside of the retaining wall to expose the inner surface of the retaining wall, A step of constructing a frame of the outer peripheral portion of the structure along the inner surface of the retaining wall, a step of excavating the floor of the retaining wall to perform flooring, and the outer peripheral portion on the inner side of the excavated retaining wall. A step of constructing the remaining structure of the underground structure integrally with the structure of the underground structure, and a method of constructing the underground structure including the maximum of the retaining wall when the structure of the underground structure is constructed over the entire plane. The data indicating the relationship between the ratio of the maximum displacement of the retaining wall and the width dimension of the outer peripheral portion of the underground structure when a frame of the outer peripheral portion of the underground structure with respect to the displacement is assumed. For each ground type Created and based on the data according to the ground type of the construction site, the ratio of the retaining wall with respect to the maximum displacement of the retaining wall when the underground structure is constructed over the entire plane The method may be a method of reading the width dimension that is a ratio of the allowable displacement and constructing a frame of the outer peripheral portion of the underground structure with the width dimension.

  Due to such characteristics, the outer peripheral portion of the underground structure is controlled so that the displacement of the retaining wall is suppressed to a desired allowable displacement or less while suppressing the width dimension of the outer peripheral portion of the previously constructed underground structure to the minimum necessary. The width dimension is determined.

  According to the construction method of an underground structure according to the present invention, since the width dimension of the outer peripheral portion of the underground structure to be constructed in advance can be set to the minimum necessary, It can function properly as a work, and the opening area inside the outer peripheral part of the underground structure to be constructed in advance can be widened to ensure workability.

It is a flowchart figure for demonstrating embodiment of this invention. It is sectional drawing for demonstrating embodiment of this invention. It is a top view for demonstrating embodiment of this invention. It is sectional drawing for demonstrating embodiment of this invention. It is sectional drawing for demonstrating embodiment of this invention. It is a top view for demonstrating embodiment of this invention. It is sectional drawing for demonstrating embodiment of this invention. It is sectional drawing for demonstrating embodiment of this invention. It is sectional drawing for demonstrating embodiment of this invention. It is sectional drawing for demonstrating embodiment of this invention. (A) is a graph showing the relationship between the maximum displacement ratio [δmax / δmaxful] of the retaining wall and the width ratio [W / L _E ] of the outer periphery when the planar shape of the underground excavation part is a square, (b) Is a graph showing the relationship between the long side maximum displacement / equal side maximum displacement ratio [δmaxL / δmaxE] and the long side / short side ratio [L _L / L _S ] when the planar shape of the building underground excavation is rectangular. . It is a flowchart figure showing the determination method of the width dimension W of the outer peripheral part of an underground structure. It is a top view showing the construction method of the underground structure assumed when creating the graph shown in FIG. It is sectional drawing showing the construction method of the underground structure assumed when creating the graph shown in FIG. It is a soil soil columnar figure assumed when creating the graph shown in FIG. It is a schematic diagram of the analysis model at the time of creating the graph shown in FIG. It is the table | surface which showed the item of each structural member assumed when producing the graph shown in FIG. It is a graph which shows the relationship between the maximum displacement ratio [(delta) max / (delta) maxful] and the width dimension W of the outer peripheral part of an underground structure. It is a flowchart figure for demonstrating other embodiment of this invention. It is sectional drawing for demonstrating other embodiment of this invention. It is a top view for demonstrating other embodiment of this invention. It is a top view for demonstrating other embodiment of this invention. It is a top view for demonstrating other embodiment of this invention. It is a top view for demonstrating other embodiment of this invention. It is a top view for demonstrating other embodiment of this invention.

  Hereinafter, an embodiment of a construction method for an underground structure according to the present invention will be described with reference to the drawings.

[Mounting process]
First, as shown in FIGS. 1 to 3, a mountain retaining process for constructing a mountain retaining wall 1 along the outer edge of the excavation region X is performed. The excavation area X is an area excavated for constructing an underground structure 10 (shown in FIG. 10) described later, and is not limited to an area having a shape along the outer shape of the underground structure 10, but at least an underground structure on the inside. 10 is an area of a size that can be arranged. In FIG. 2, the excavation area X has a rectangular shape in plan view, but the shape of the excavation area X can be changed as appropriate, and may be, for example, an L shape in plan view or other shapes. The retaining wall 1 is a wall body arranged outside the underground structure 10 and is constructed such that its inner surface is in contact with the outer edge of the excavation region X described above. As a method for constructing the mountain retaining wall 1, a known mountain retaining method such as an underground continuous wall method, a soil cement column wall method, a parent pile sheet pile method, or the like can be employed.

[Primary excavation process]
Next, as shown in FIGS. 1 and 4, a primary excavation process for excavating the inside of the retaining wall 1 is performed. In this step, the inner surface of the upper portion of the retaining wall 1 is exposed and excavated to such a depth that an outer peripheral portion 11a (shown in FIG. 5) of the first-story beam slab 11 described later can be constructed.

[1st floor beam slab outer circumference advance construction process]
Next, as shown in FIGS. 1, 5, and 6, a first-story beam slab outer periphery advance construction process for constructing the outer peripheral portion 11 a of the first-story beam slab 11 along the inner surface of the retaining wall 1 is performed. The outer peripheral part 11 a of the first-story beam slab 11 described above is a structure of the underground structure 10 made of reinforced concrete, and is formed in a rectangular frame (annular shape) in plan view along the inner surface of the retaining wall 1. More specifically, the outer peripheral portion 11a of the first floor beam slab 11 is extended along the outer peripheral portion 12a of the first floor slab 12 of the underground structure 10 and the outer edge of the underground structure 10, and the first floor slab 12 described above. A first floor outer beam 13 that supports the outer peripheral portion 12a and an outer end portion 14a of the first floor inner beam 14 that extends in a direction orthogonal to the first floor outer beam 13 and supports the outer peripheral portion 12a of the first floor slab 12 described above. And is composed of.

  As a method of constructing the outer peripheral part 11a of the first-story beam slab 11, for example, first, a beam slab form (not shown) of the outer peripheral part 11a of the first-story beam slab 11 is built along the inner surface of the retaining wall 1, Reinforcing bars (not shown) of the outer peripheral portion 11a of the first floor beam slab 11 are placed in the beam slab formwork, and then concrete is placed in the beam slab formwork. Then, after the concrete is solidified, the above-described beam slab form is removed, and the outer peripheral portion 11a of the first-story beam slab 11 is completed. Thereby, the outer peripheral part 11a of the first-story beam slab 11 constructed in advance functions as a support work, and the retaining wall 1 is supported by the outer peripheral part 11a. In addition, the outer peripheral part 11a of the first-story beam slab 11 may be supported in the vertical direction by a not-shown construction pillar placed on the ground before the primary excavation process, or the inner surface of the retaining wall 1 and the first floor It may be supported in the vertical direction by a cane that is obliquely installed between the lower surface of the outer end portion 14 a of the inner beam 14, or is projected on the steel material of the retaining wall 1 and fixed to the first floor outer beam 13. You may support in the perpendicular direction by the made stud connector.

[Drilling process after n]
Next, as shown in FIGS. 1 and 7, an excavation process is performed in which a secondary excavation process for excavating the inside of the retaining wall 1 is performed. In this excavation process, the inside of the retaining wall 1 is excavated stepwise, the inner surface of the retaining wall 1 is exposed, and flooring is performed when the interior is excavated to a predetermined depth. Moreover, since the inner side of the outer peripheral part 11a of the first-story beam slab 11 constructed in advance is in an open state, the excavated residual soil is carried out through the inner side of the outer peripheral part 11a.

[Basic construction process]
Next, as shown in FIGS. 1 and 8, a foundation 15 is constructed on the flooring surface 2 inside the mountain retaining wall 1. The foundation 15 is a reinforced concrete structure such as a pressure platen, and is formed on the entire flooring surface 2. More specifically, after arranging reinforcing bars on the flooring surface 2, concrete is placed to form the foundation 15. At this time, materials such as reinforcing bars of the foundation 15 are carried on the flooring surface 2 in the retaining wall 1 through the inside of the outer peripheral portion 11a of the first-story beam slab 11 constructed in advance.

[Underground building construction process]
Next, as shown in FIGS. 1, 9, and 10, the underground floors 12, 16 to 18 are sequentially constructed from the lower floor inside the retaining wall 1. More specifically, first, as shown in FIG. 9, a step of constructing the B2 floor column wall 16 and the B1 floor beam slab 17 on the foundation 15 is performed. Next, as shown in FIG. 10, on the B1 floor beam slab 17, the B1 floor column wall 18, the remaining portion of the first floor slab 12 (inner portion 12b) and the remaining portion of the first floor inner beam 14 ( A step of constructing the central portion 14b) integrally with the outer peripheral portion 11a of the first-story beam slab 11 is performed. At this time, materials such as reinforcing bars and forms for the frame bodies 12 and 16 to 18 in the basement floor, and equipment used for the construction are mountain retaining walls through the inner side of the outer peripheral portion 11a of the first floor beam slab 11 constructed in advance. Carry in 1.
The underground structure 10 is constructed by the above steps.

  By the way, the width dimension W of the outer peripheral part 11a of the above-mentioned first floor beam slab 11 is determined by a different calculation method depending on the ground type of the construction site.

First, for each soil type of construction where it is assumed, the maximum displacement ratio [δmaxE / δmaxful] and the outer peripheral slab width ratio of earth retaining wall 1 when the planar shape of a building underground excavation is square equilateral length L _E [W / L _E ] and the data 1 (graph shown in FIG. 11A) and the plan shape of the building underground excavation are rectangles having a short side length L _S = L _E and a long side length L _L ≧ L _S Data 2 showing the relationship between the long side maximum displacement / equal side maximum displacement ratio [δmaxL / δmaxE] and the long side / short side ratio [L _L / L _S ] of the retaining wall 1 in FIG. Graph) shown in FIG. Maximum displacement ratio [δmaxE / δmaxful] is 1 Kaihari precursor whole plane 1 Kaihari slab to the maximum displacement Derutamaxful the earth retaining wall 1 when constructed over the (square equilateral length L _E) 11 of the slab 11 and the This is the ratio of the maximum displacement δmaxE of the retaining wall 1 when the casing of the outer peripheral portion 11a is constructed. Periphery slab width ratio [W / L _E] is the ratio of the width W of the outer peripheral portion 11a with respect equilateral length L _E of 1 Kaihari slab 11. Long side maximum displacement / equilateral maximum displacement ratio [δmaxL / δmaxE] is 1 in a case where to construct a skeleton of the outer peripheral portion 11a of the Kaihari slab 11, the planar shape of a building underground excavation is a square equilateral length L _E The maximum long side of the retaining wall 1 when the plan shape of the underground excavation part is a rectangle with a short side length L _S = L _E and a long side length L _L ≧ L _S with respect to the maximum equal displacement δmaxE of the retaining wall 1 in some cases This is the ratio of the displacement ΔmaxL. The long side / short side ratio [L _L / L _S ] is the long side length with respect to the short side length L _{S when} the plan shape of the building underground excavation part is short side length L _S = L _E and long side length L _L ≧ L _S L is the ratio of _L.

Subsequently, as shown in FIG. 12, the same level of displacement suppression effect as that of the case where the frame of the first-story beam slab 11 is constructed over the entire plane is expected in the outer peripheral portion 11a of the first-story beam slab 11 constructed in advance. The step of selecting whether or not to perform is performed. When the displacement suppression effect is expected, data corresponding to the ground type of the construction site, the short side length L _S , and the long side / short side ratio [L _L / L _S ] among the data shown in FIG. Based on 1 or data 2, the outer peripheral slab width ratio [W / L _E ] at which the long side maximum displacement ratio [δmaxL / δmaxful] = [δmaxL / δmaxE] × [δmaxE / δmaxful] is 1 is read. Then, a frame of the outer peripheral portion 11a of the first-story beam slab 11 is constructed with a width dimension W obtained by multiplying the read outer peripheral slab width ratio [W / L _E ] by the short side length L _S = L _E.

  On the other hand, when the displacement suppression effect of the same level as the case where the frame of the first floor beam slab 11 is constructed over the entire plane is not expected, the width dimension W of the outer peripheral portion 11a of the first floor beam slab 11 is allowed in construction. Set to the desired dimension. In this case, first, as shown in FIG. 12, an allowable displacement δal of the retaining wall 1 is set. Further, the maximum displacement δmaxful when the frame of the first-story beam slab 11 is constructed over the entire plane is calculated. As a calculation method of the maximum displacement δmaxful, a beam / spring model, a plate / spring model, a finite element method, and other empirical methods can be used.

Subsequently, as shown in FIG. 12, a step of selecting whether or not the allowable displacement δal is equal to or larger than the maximum displacement δmaxful is performed. When the allowable displacement δal is equal to or greater than the maximum displacement δmaxful, the data shown in FIG. 11 corresponds to the ground type of the construction site, the short side length L _S , and the long side / short side ratio [L _L / L _S ]. Based on the data 1 or data 2, the longest side maximum displacement ratio [δmaxL / δmaxful] = [δmaxL / δmaxE] × [δmaxE / δmaxful] becomes the permissible displacement ratio [δal / δmaxful] [W / Read [L _E ]. Then, a frame of the outer peripheral portion 11a of the first-story beam slab 11 is constructed with a width dimension W obtained by multiplying the read outer peripheral slab width ratio [W / L _E ] by the short side length L _S = L _E. The allowable displacement ratio [δal / δmaxful] is a ratio of the allowable displacement δal to the maximum displacement δmaxful of the retaining wall 1 when the frame of the first-story beam slab 11 is constructed over the entire plane.

  Further, when the allowable displacement δal is smaller than the maximum displacement δmaxful, the required displacement suppressing effect cannot be exhibited only by the outer peripheral portion 11a of the first floor beam slab 11, and therefore the outer peripheral portion 11a of the first floor beam slab 11 is. Whether or not to adopt a method for supporting the retaining wall 1 is considered. And when employ | adopting the said construction method, after giving the auxiliary construction method which suppresses the displacement of the retaining wall 1, it is a displacement comparable as the case where the frame of the 1st floor beam slab 11 mentioned above is constructed | assembled over all planes. Returning to the step of selecting whether or not the suppression effect is expected on the outer peripheral portion 11a of the first floor beam slab 11, the review is performed. In addition, as the above-mentioned auxiliary construction method, for example, a cut beam 31 and an erection 30 as shown in FIG. 24 to be described later are installed inside the retaining wall 1 or a retaining anchor as shown in FIG. 25 to be described later. 32 is installed on the ground, or a known ground improvement method is performed on the ground.

Also, a method for creating the data shown in FIG. 11 will be described.
First, the underground structure assumed when creating the data shown in Fig. 11 is from 8m x 8m (8m x 8m grid 1 span x 1 span) to 80m x 80m (8m x 8m grid 10 span x 10 span) ) Square or a rectangle with a short side length of 24 m (8 m grid, 3 spans) and a long side length of 32 m (8 m grid, 4 spans) to 80 m (8 m grid, 10 spans), and the foundation structure is a solid foundation It is a reinforced concrete structure on the 2nd basement floor, and its lower end depth (excavation depth) is GL (ground line) -12m. As an example of the planar dimensions of the structure, a 24 m × 40 m (8 m × 8 m grid short side direction 3 span, long side direction 5 span) is shown in FIG. The assumed retaining wall is a soil cement column wall (mounting core: H-500 × 200 × 10 × 16 @ 600), and the lower end depth is GL-20m.

  Moreover, as an assumed construction procedure, as shown in FIG. 14, after constructing the assumed retaining wall 101, (1) primary excavation to GL-2m is performed. However, in the case of a saturated sandy soil layer, the water level is lowered to GL-3m. (2) Next, the outer wall (outer peripheral beam) 113 up to GL-2m and the outer periphery 112 of the first floor slab (upper surface level: GL ± 0m) are constructed. (3) Next, secondary excavation is performed up to GL-6m. However, in the case of a saturated sandy soil layer, the water level is lowered to GL-7m. (4) Next, the outer wall (outer peripheral beam) 123 up to GL-5m and the outer periphery 122 of the first basement floor slab (upper surface level: GL-4m) are constructed. (5) Next, perform the third excavation to GL-12m and floor it. However, in the case of a saturated sandy soil layer, the water level is lowered to GL-13m.

  As assumed ground types, two ground types, a hard ground and a soft ground, are used as models. The hard ground of this model ground includes those with old age and low groundwater level among the Hirosaki Plateau and alluvial plains, and soft ground with new ground age and high groundwater level among alluvial plains, Includes landfill.

  As shown in FIG. 16, the numerical analysis is performed using a plate / spring model in which the beam / spring model is expanded three-dimensionally. In this analysis model, the quarter slab cut along the symmetry planes in both the short side and the long side directions, the outer peripheral portions 112 and 122 of the floor slab, the outer walls 113 and 123, and the mountain retaining wall 101 (soil cement 101) shown in FIG. The wall) is modeled with an elastic plate element, the retaining core is modeled with an elastic beam element, and the ground is modeled with a spring element. For the ground spring, linear elastic springs (no upper limit of spring force) acting only on the compression side are installed on both sides of the retaining wall 101 (on both sides of the retaining core) at 1 m pitches in the vertical and horizontal directions. To do. Columns, beams and inner walls are not considered as structural elements. The specifications of the structural members are as shown in FIG. In addition, the boundary condition is a rotation restraint roller in both horizontal and vertical directions on the symmetry plane, and a lower end (GL-20m) is a horizontal bi-directional pin roller.

Further, this analysis is performed by repeating the procedure of removing the ground spring at the excavation portion and applying a side pressure to the elastic plate element of the retaining wall 101 and the procedure of adding the structural element corresponding to the construction procedure. The lateral pressure is calculated by the lateral pressure coefficient method, considering 20kN / m ² as an overload. Considering the decrease of the equilibrium side pressure and the water pressure on the excavation side for the root portion of the retaining wall 101. The plane pressure distribution is uniform on each side.

  Then, for each of the above assumed ground types, analysis is performed by changing the width dimension W of the outer periphery 111 of the casing (the outer periphery 112, 122 of the floor slab), and FIG. 18 shows a case where the planar dimension is 24 m × 40 m. Thus, the ratio [δmax / δmaxful] of the maximum displacement δmax of the retaining wall 101 during the secondary excavation and the tertiary excavation with respect to the maximum displacement δmaxful of the retaining wall 101 when the frame of the underground structure is constructed over the entire plane Plot.

A series of analyzes in which the equilateral length L _E is changed from 8 m to 80 m when the planar shape is a square is performed, and a regression analysis of the result is performed to determine the maximum displacement ratio [δmaxE / δmaxful] of the retaining wall 101 and the equilateral length L _E. that the relationship between the ratio of the width dimension W of the building frame peripheral portion 111 [W / L _E], indicated for soil type and equilateral length L _E for is data 1 in FIG. 11 (a).

Furthermore, when the planar shape is rectangular, the short side length L _S is fixed at 24 m, the long side length L _L is changed from 24 m to 80 m, a series of analyzes are performed, and the regression analysis of the results is performed. maximum displacement DerutamaxL ratio [δmaxL / δmaxE] with short side length L ratio of long side length L _L for _S in the case of increasing the long side length L _L with respect to the maximum displacement DerutamaxE the earth retaining wall 101 in the [L _L / the relationship between L _S], is a data 2 shown in FIG. 11 (b) shows relative ratio of the width dimension W of the skeleton outer peripheral portion 111 for soil type and short side length L _S [W / L _S] .

By using a combination of data 1 in FIG. 11A and data 2 in FIG. 11B, the long-side maximum displacement ratio [δmaxL / δmaxful] of the retaining wall in an arbitrary rectangular plane can be obtained. That reads 11 Retaining wall equilateral maximum displacement ratio to soil type and equilateral length L _E from the data 1 (a) [δmaxE / δmaxful] , soil type and the outer peripheral slabs from the data 2 shown in FIG. 11 (b) The long side maximum displacement / equal side maximum displacement ratio [δmaxL / δmaxE] is read from the width ratio [W / L _S ] and multiplied to obtain the value of the long side maximum displacement ratio [δmaxL / δmaxful]. It is done.
When the width W of the outer periphery of the frame is the same in both the short and long sides, the maximum displacement δmaxS of the retaining wall in the short side direction is smaller than the maximum displacement δmaxL of the retaining wall in the long side direction. Only need to be considered.

  In FIG. 18, since the values in the secondary excavation and the tertiary excavation having different excavation depths are almost the same, even if the excavation depth is changed, it can be considered that the result in FIG. 18 does not change. FIG. 12 is an analysis result obtained from the average value of the secondary excavation and the tertiary excavation in FIG. 18, and can be said to be applicable for general purposes regardless of the excavation depth.

  According to the construction method of the underground structure 10 described above, the width dimension W where the maximum displacement ratio [δmaxL / δmaxful] is 1 is read based on the data (shown in FIG. 11) according to the ground type of the construction site. Thus, the retaining wall 1 to the same extent as when the frame of the first-story beam slab 11 is constructed over the entire plane while suppressing the width dimension W of the outer peripheral portion 11a of the first-story beam slab 11 to be constructed to the minimum necessary. The width dimension W of the outer peripheral portion 11a of the first floor beam slab 11 is determined so that the displacement of the first floor beam slab 11 is suppressed.

  Further, by reading the width dimension W where the maximum displacement ratio [δmaxL / δmaxful] becomes the allowable displacement ratio [δal / δmaxful] based on the data according to the ground type of the construction site (shown in FIG. 11), the first floor The width dimension of the outer peripheral part 11a of the first floor beam slab 11 is controlled so that the displacement of the retaining wall 1 is suppressed to a desired allowable displacement δal or less while the width dimension W of the outer peripheral part 11a of the beam slab 11 is minimized. W is determined.

  As described above, since the width dimension W of the outer peripheral portion 11a of the first floor beam slab 11 to be constructed in advance can be set to the minimum necessary, the outer peripheral portion 11a of the first floor beam slab 11 to be constructed in advance is used as a mountain support work. It can be made to function properly, and the opening area inside the outer peripheral part 11a of the first-story beam slab 11 to be constructed in advance can be widened to ensure workability.

As mentioned above, although embodiment of the construction method of the underground structure which concerns on this invention was described, this invention is not limited to above-described embodiment, In the range which does not deviate from the meaning, it can change suitably.
For example, in the above-described embodiment, only the outer peripheral portion 11a of the first floor beam slab 11 is preliminarily constructed. However, the present invention also applies to the outer peripheral portion of the beam slab on the intermediate underground floor according to the ground condition and the excavation scale. You may build ahead sequentially. More specifically, as shown in FIG. 19, after the primary excavation process, the first-stage beam slab outer periphery advance construction process for constructing the outer peripheral portion 11a of the first-floor beam slab 11 is performed, and then the second excavation process is performed. . In this secondary excavation process, the inner surface of the retaining wall 1 below the outer peripheral portion 11a of the first-story beam slab 11 is exposed and excavated to such a depth that the outer peripheral portion 17a of the B1 floor-beam slab 17 can be constructed. Then, the B1 floor beam slab outer periphery advance construction | assembly process which builds the outer peripheral part 17a of the B1 floor beam slab 17 along the inner surface of the retaining wall 1 is performed similarly to the outer periphery part 11a of the 1st floor beam slab 11 mentioned above. Then, after the outer peripheral portion 17a of the B1 floor beam slab 17 is completed, a tertiary excavation process is performed as shown in FIGS. Thereby, the fall (horizontal displacement) of the mountain retaining wall 1 can be suppressed more reliably. In addition, when the underground floor of the underground structure 10 is three or more underground floors, excavation is advanced while the above excavation process and the beam slab outer periphery advance construction process of the underground floor are alternately repeated.

  Further, in the above-described embodiment, the outer peripheral portion 11a of the first floor beam slab 11 constructed in advance is extended over the entire circumference of the first floor beam slab 11 to form an annular shape. As shown in FIG. 21, a part of the outer periphery of the underground structure 10 may be preliminarily constructed. For example, as shown in FIG. 21A, the outer peripheral portion of the underground structure 10 is preliminarily constructed without forming a portion on one side, and the outer peripheral portion 11b having a substantially U-shape in plan view. May be formed. Further, as shown in FIG. 21 (b), among the outer peripheral portions of the underground structure 10, the remaining portions are constructed in advance without forming the adjacent two surface side portions, and the outer periphery is substantially L-shaped in plan view. The part 11c may be formed. Moreover, as shown in FIG.21 (c), the remaining part is formed ahead of the outer peripheral part of the underground structure 10, without forming the part of 2 surfaces which oppose, and it is I character shape which is parallel in planar view The outer peripheral portion 11d may be formed. Moreover, as shown in FIG.21 (d), only the part of the 1st surface side among the outer peripheral parts of the underground structure 10 may be constructed | assembled in advance, and the outer peripheral part 11e of planar view I shape may be formed. Furthermore, as shown to (a)-(c) of FIG. 22, when the planar view shape of the underground structure 10 is other than a rectangle, according to the planar shape of the underground structure 10, various planar view shapes The outer peripheral portions 11f to 11h can be constructed in advance.

Further, in the above-described embodiment, there is nothing inside the outer peripheral portion 11a of the first-stage beam slab 11 constructed in advance, and the state is completely opened. However, the present invention is as shown in FIG. The intermediate slab 11i may be installed inside the frame (the outer peripheral portion 11a of the first floor beam slab 11) in the outer peripheral portion of the underground structure 10.
Moreover, in the above-described embodiment, the retaining wall 1 is supported only by the outer peripheral portion 11a of the first-story beam slab 11 constructed in advance, but the present invention is a frame (first floor) of the outer peripheral portion of the underground structure 10 It is also possible to support the retaining wall 1 by using the outer peripheral portion 11a) of the beam slab 11 in combination with a temporary support member. For example, as shown in FIG. 24, it is possible to use both the outer peripheral portion 11d of the first-stage beam slab 11 constructed in advance and the support work composed of the erection 30 and the cut beam 31, or As shown in FIG. 25, it is also possible to use the outer peripheral portion 11b of the first floor beam slab 11 constructed in advance and the earth retaining anchor 32 in combination.

  In the above-described embodiment, the step of constructing the outer peripheral portion 11a of the first-story beam slab 11 is performed after the primary excavation step. However, in the present invention, the casing constructed after the primary excavation step is 1 It is not limited to the outer peripheral part 11 a of the floor beam slab 11, and may be a frame of the outer peripheral part of the underground structure 10. For example, only the outer peripheral part of the first-floor beam may be constructed, or the underground first-floor wall, the underground first-floor pillar, and the like located in the outer peripheral part of the underground structure 10 may be constructed.

  In the above-described embodiment, the outer peripheral portion 11a of the reinforced concrete first-story beam slab 11 is preliminarily constructed by the in-situ construction method. However, the present invention is not limited to this, and the first-story beam is constructed by other construction methods. The outer peripheral part 11a of the slab 11 may be constructed in advance, or the outer peripheral part 11a of the first-story beam slab 11 having another structure may be constructed in advance. For example, any one of the first floor slab 12, the first floor outer beam 13 and the first floor inner beam 14 is made of precast concrete (PC), and the PC method for assembling the PC member or the concrete placement after the PC member is assembled. It is also possible to pre-construct the outer peripheral portion 11a of the first-story beam slab 11 by the half PC method for performing the above. Alternatively, the first-floor slab 12 may be a slab having a deck slab structure, or the first-floor outer peripheral beam 13 and the first-floor inner beam 14 may be steel frames.

  In addition, in the range which does not deviate from the main point of this invention, it is possible to replace suitably the component in above-mentioned embodiment with a well-known component, and you may combine the above-mentioned modification suitably.

1 mountain retaining wall 10 underground structure 11a outer peripheral part (frame of outer peripheral part)

Claims (2)

Building a retaining wall along the outer edge of the excavation area;
Drilling the inside of the retaining wall to expose the inner surface of the retaining wall;
Constructing a frame of the outer peripheral portion of the underground structure along the inner surface of the retaining wall;
Excavating the inside of the retaining wall for flooring;
A step of constructing the remaining frame of the underground structure integrally with the frame of the outer peripheral portion inside the excavated retaining wall;
In the construction method of the underground structure comprising
The ratio of the maximum displacement of the retaining wall when constructing the outer periphery of the underground structure to the maximum displacement of the retaining wall when the underground structure is constructed over the entire plane, and the underground structure Create the data indicating the relationship between the width dimension of the outer peripheral part of the object for each of a plurality of assumed ground types,
Based on the data according to the ground type of the construction site, the width dimension at which the ratio is 1 is read, and the outer peripheral portion of the underground structure is constructed with the width dimension. Construction method. Building a retaining wall along the outer edge of the excavation area;
Drilling the inside of the retaining wall to expose the inner surface of the retaining wall;
Constructing a frame of the outer peripheral portion of the underground structure along the inner surface of the retaining wall;
Excavating the inside of the retaining wall for flooring;
A step of constructing the remaining frame of the underground structure integrally with the frame of the outer peripheral portion inside the excavated retaining wall;
In the construction method of the underground structure comprising
The ratio of the maximum displacement of the retaining wall when constructing the outer periphery of the underground structure to the maximum displacement of the retaining wall when the underground structure is constructed over the entire plane, and the underground structure Create the data indicating the relationship between the width dimension of the outer peripheral part of the object for each of a plurality of assumed ground types,
Based on the data according to the ground type of the construction site, the ratio is the ratio of the allowable displacement of the retaining wall to the maximum displacement of the retaining wall when the frame of the underground structure is constructed over all planes. The construction method of the underground structure characterized by reading the said width dimension, and constructing the frame of the outer peripheral part of the said underground structure with this width dimension.

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