Soil retaining method and soil retaining structure

Abstract

To provide a soil retaining method and a soil retaining structure capable of reducing the number of stages of struts for optimization.SOLUTION: A soil retaining method using an existing underground skeleton as a soil retaining wall 1, comprises steps of: installing wales 2 on the soil retaining wall 1; installing struts 4 on a plurality of wales 2; and introducing preload on the existing underground skeleton with a jack device 5 installed on the strut 4. The struts 4 extend in an intersecting direction to the soil retaining wall 1 in plan view, and the struts 4 are installed between a wall part 11 extending in a long side direction and a wall part 11 extending in a short side direction.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an earth retaining method and an earth retaining structure. [Background technology]

[0002] Conventionally, when planning underground construction to demolish an existing building and construct a new building, there is a method of using the basement walls of the existing building as earth retaining walls (see Patent Document 1 below). In this method, struts and wales are set so that the stress acting on the basement walls of the existing building does not exceed specified values ​​(short-term allowable stress level, crack strength, etc.). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2011-163074 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, although preloading is introduced to the struts, this is for the purpose of making the members adhere to each other and stabilizing the struts, and is not taken into consideration in the calculation of the earth retaining. It is desirable to apply an appropriate preload to the existing basement walls and reduce and optimize the number of struts.

[0005] In view of the above circumstances, the present invention provides an earth retaining method and an earth retaining structure that can reduce and optimize the number of strut stages. [Means for solving the problem]

[0006] In order to achieve the above object, the present invention employs the following means. In other words, the retaining method of the present invention is a retaining method that utilizes the existing underground structure as an earth retaining wall, in which wales are installed on the earth retaining wall, struts are erected on a plurality of the wales, and a preload is introduced to the existing underground structure using a jack device installed on the struts.

[0007] In this earth retaining method, a preload is applied to the existing underground structure using a jacking device, which reduces the stress acting on the existing underground structure and optimizes the number of struts.

[0008] In addition, the retaining construction method of the present invention comprises a retaining wall composed of an existing underground structure, a wale installed on the retaining wall, struts erected on a plurality of the wale, and a jack device installed on the struts and introducing a preload into the existing underground structure.

[0009] In this earth retaining method, a preload is applied to the existing underground structure using a jacking device, which reduces the stress acting on the existing underground structure and optimizes the number of struts.

[0010] In addition, in the retaining structure according to the present invention, the strut may extend in a direction intersecting the retaining wall in a plan view.

[0011] In a retaining structure configured in this manner, in plan view, the struts are extended in a direction intersecting the retaining wall, and by positioning the struts near the corners of the retaining wall, a large space can be formed in the center of the retaining wall in plan view. Effect of the Invention

[0012] According to the earth retaining construction method and earth retaining structure of the present invention, the number of strut sections can be reduced and optimized. [Brief description of the drawings]

[0013] [Figure 1] FIG. 2 is a plan view illustrating a retaining construction method according to an embodiment of the present invention. [Diagram 2] FIG. 2 is an enlarged view of part II in FIG. [Diagram 3] FIG. 2 is an enlarged view of part III in FIG. [Figure 4] FIG. 2 is a schematic vertical cross-sectional view illustrating an earth retaining method according to one embodiment of the present invention. [Diagram 5] FIG. 5 is a schematic vertical sectional view illustrating the earth retaining method according to one embodiment of the present invention, showing a step subsequent to the step shown in FIG. 4. [Figure 6] FIG. 6 is a schematic vertical sectional view illustrating an earth retaining method according to an embodiment of the present invention, showing a step subsequent to the step shown in FIG. 5. [Figure 7] (a) The top diagram shows earth pressure, and the bottom diagram is a moment diagram. (b) The top diagram explains the action of axial force in a conventional method, and the bottom diagram is a moment diagram. (c) The top diagram explains the action of axial force in an earth retaining method according to one embodiment of the present invention, and the bottom diagram is a moment diagram. [Figure 8] 1A and 1B show the moments when considering an existing underground exterior wall, where (a) is a moment diagram for the conventional method (not taking into account the effect of N1), and (b) is a moment diagram when applying the earth retaining method according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, an earth retaining method and an earth retaining structure according to an embodiment of the present invention will be described. The following embodiment shows one aspect of the present disclosure, does not limit the present disclosure, and can be modified as desired within the scope of the technical idea of ​​the present disclosure. In the following drawings, the scale of each structure is different from the actual structure in order to make each configuration easier to understand.

[0015] FIG. 1 is a plan view illustrating an earth retaining method according to one embodiment of the present invention. As shown in Fig. 1, the earth retaining method according to this embodiment is a method in which the exterior walls of an existing underground structure are used as an earth retaining wall when constructing a new underground structure after demolishing the existing underground structure excluding the exterior walls. The earth retaining structure 100 constructed by the earth retaining method includes an earth retaining wall 1, a wale 2, a strut 4, and a jack device 5.

[0016] The earth retaining wall 1 has a substantially rectangular shape in a plan view. For convenience, the long side direction of the earth retaining wall 1 is indicated by an arrow X, and the short side direction is indicated by an arrow Y.

[0017] The earth retaining wall 1 is composed of the existing underground structure. The earth retaining wall 1 has a wall portion 11 and a pillar 12. It is sufficient for the earth retaining wall 1 to have only the wall portion 11, and it is not necessary for it to have the pillar 12. In the embodiment shown above, the pillar 12 arranged along the short side direction (arrow Y) is dismantled in advance because it interferes with the newly built underground structure, and the short side direction is composed of only the wall portion 11.

[0018] The wall portions 11 are arranged along the outer edge of a substantially rectangular shape in plan view. The shape formed by the wall portions 11 can be set as appropriate. The wall portions 11 along the long side direction of the earth retaining wall 1 are referred to as wall portions 11a and 11b. The wall portions 11 along the short side direction of the earth retaining wall 1 are referred to as wall portions 11c and 11d.

[0019] The pillars 12 are disposed along the walls 11a and 11b. A plurality of pillars 12 are disposed at intervals in the long side direction.

[0020] The wale 2 is disposed along the inner surface 11e of the wall portion 11. The wale 2 is made of an H-shaped steel beam, but steel materials with other cross sections may also be used.

[0021] In the walls 11a, 11c, and 11d, the pelvic raised portions 2 are arranged in two rows along the inner surface 11e of the wall 11. In the joint A shown in Fig. 2, the pelvic raised portion 2 arranged closer to the wall 11 is referred to as the pelvic raised portion 2a, and the pelvic raised portion 2 arranged farther from the wall 11 is referred to as the pelvic raised portion 2b. The number of rows of the pelvic raised portions 2 can be set appropriately.

[0022] A filler 21 such as grout is filled between the wall portion 11 and the wale 2a. The wale 2a is fixed to the wall portion 11 with a fastener 22 such as a Chemical Anchor (registered trademark). The fastener 22 is embedded in the filler 21. The wale 2a and the wale 2b are fixed with a fastener 23 such as a high tension bolt. In the walls 11a, 11c, and 11d, the wale 2 is directly fixed to the wall portion 11.

[0023] 1, in the wall portion 11b, the ribs 2 are arranged in one row along the inner surface 11e of the wall portion 11. The number of rows of the ribs 2 can be set appropriately.

[0024] At joint B shown in Fig. 3, connecting steel materials 26 are installed between wall portion 11b and the wale 2. The connecting steel materials 26 are installed in two stages, but the number of stages can be set appropriately. The connecting steel material 26 arranged closer to wall portion 11b is referred to as connecting steel material 26a, and the connecting steel material 26 arranged further from wall portion 11 is referred to as connecting steel material 26b. The connecting steel materials 26a and 26b are fixed together with fasteners 27 such as high tension bolts.

[0025] A filler 28 such as grout is filled between the joint steel material 26a and the wall portion 11b and the column 12. The joint steel material 26a is fixed to the wall portion 11b with a fastener 29 such as a Chemical Anchor (registered trademark). The fastener 29 is embedded in the filler 28.

[0026] The connecting steel material 26b is fixed to the wale 2 with a fastener 30 such as a Chemical Anchor (registered trademark). A corner metal 32 is provided at a corner where the connecting steel material 26b and the wale 2 form a right angle. The corner metal 32 is fixed to the connecting steel material 26b with a fastener (not shown), and is also fixed to the wale 2 with a fastener 33 such as a Chemical Anchor (registered trademark). In the wall portion 11b, the wale 2 is fixed to the wall portion 11b via the connecting steel material 26.

[0027] As shown in FIG. 1, the struts 4 are erected on perpendicular wall portions 11. The struts 4 are erected between the wall portions 11 extending in the long side direction and the wall portions 11 extending in the short side direction. In plan view, the struts 4 extend in a direction intersecting the wall portions 11. The wall portions 11 are formed by joining a plurality of steel materials such as H-beams and steel pipes in the longitudinal direction. The struts 4 extend in a direction intersecting the long side direction and the short side direction. The struts 4 are installed near the four corners of the earth retaining wall 1. The struts 4 are installed in multiple stages in parallel at each corner. In a region including the center of the earth retaining wall 1 in plan view, a space S that communicates in the vertical direction is formed.

[0028] At joint A shown in Fig. 2, two struts 4 are joined in a V-shape to the wale 2. The longitudinal ends of the two struts 4 are fixed to joint metal fittings 41 with fasteners 42 such as high tension bolts. The joint metal fittings 41 are fixed to the wale 2b with fasteners 43 such as high tension bolts. The struts 4 are joined to the wale 2 via the joint metal fittings 41.

[0029] At joint B shown in Fig. 3, the longitudinal end of the strut 4 is fixed to a joint metal 46 with a fastener 47 such as a high tension bolt. The joint metal 46 is fixed to the wale 2 with a fastener 48 such as a high tension bolt. The strut 4 is joined to the wale 2 via the joint metal 46. A column 12 is arranged on an extension line D of the strut 4.

[0030] The jacking device 5 is installed on the strut 4. The jacking device 5 is, for example, configured by a well-known preload jack. When the wale 2 is fixed to the earth retaining wall 1, as in joint A shown in Figure 2, the preload introduced from the jacking device 5 acts on the earth retaining wall 1 via the wale 2. When a column 12 is placed on the extension line D of the strut 4, as in joint B shown in Figure 3, the preload introduced from the jacking device 5 acts on the column 12 via the wale 2.

[0031] Next, the earth retaining construction method according to this embodiment will be described. A wale 2 is installed on the inner surface of the earth retaining wall 1. As shown in Figure 4, a primary excavation is performed by excavating a backfilled area 14 filled with soil and sand to a predetermined depth. The number of stages of struts is determined based on the construction plan. A strut 4 for the first stage of the earth retaining wall is erected. In this embodiment, only one stage of struts 4 is installed. A jack device 5 is installed on the strut 4.

[0032] A three-dimensional analysis or the like is performed on the existing structure including the walls 11, columns 12, and beams 13 to determine the acting stress. A preload is set so that the acting stress is equal to or less than a specified value set based on the short-term allowable stress or crack stress of the existing underground structure.

[0033] Next, introduce the preload of the jacking device 5 installed on the cut beam 4 so as to act on the existing structures such as the wall part 11 and the column 12. The preload may not be introduced all at once, but may be increased in accordance with the progress of the undercutting work. Measure the displacement, inclination, etc. of the retaining wall 1, and adjust the value of the preload while checking against the analysis results. As shown in Fig. 5, while checking the displacement of the existing structure, perform secondary undercutting to further excavate the backfill part 14. As shown in Fig. 6, excavate the backfill part 14 to a predetermined height such as the base of the foundation of the newly constructed underground structure and complete it. In the case where the cut beam 4 has multiple stages, undercutting is sequentially performed by the same method.

[0034] It is necessary that the actual moment Md of the leg part is smaller than the allowable value (allowable moment) Ma of the existing structure. As shown in Fig. 7, in the conventional construction method, in order to make the members in close contact and stabilize the cut beam, etc., a preload N1 is introduced into the cut beam, but since its value is not managed, it is not considered in the calculation of the retaining force, and the safety of the existing structure was verified by the moment due to the earth pressure shown in Fig. 8(a). In the conventional construction method, it was necessary to use a two-stage cut beam in order to keep the acting stress of the existing structure within the allowable value. Let the leg moment (moment due to earth pressure) be Mo. It is evaluated as Md = Mo. Actually, as shown in Fig. 7(b), a moment M1 due to the axial force N1 of the cut beam also occurs, and Md = Mo is a safety-side evaluation. Therefore, if designed to satisfy this condition, there is a possibility of excessive cost. By evaluating the axial force N1 of the cut beam, the calculated value of the stress Md for existing wall consideration can also be reduced. However, with the axial force N1 of the cut beam, it is not always the case that Md < Ma.

[0035] In the bracing method of this embodiment, the axial force N2 is determined such that the working stress of the existing member is equal to or less than the specified value Ma set from the short-term allowable stress or cracking stress of the existing underground structure. Let the moment caused by the axial force N2 be M2. Calculate the moment M2 so that Md = Mo - M2 < Ma, and actually apply a preload greater than or equal to the axial force N2 that generates the moment M2. By appropriately controlling the axial force N2 and controlling the value of the moment M2, the actual moment Md of the leg can be reduced. As shown in Fig. 8(b), the stress for verifying the safety of the existing structure can be made smaller than that of the conventional construction method.

[0036] In the bracing method configured as described above, a preload is introduced into the existing underground structure such as the column 12 and the beam 13 by the jacking device 5. Therefore, the stress acting on the existing underground structure can be reduced, and the number of stages of the cut beam 4 can be reduced and optimized.

[0037] By reducing the number of stages of the cut beam 4, the cost can be reduced and the efficiency of the underground construction can be improved.

[0038] Also, in plan view, the cut beam 4 extends in a direction intersecting the bracing wall 1, and by arranging the cut beam 4 near the corner of the bracing wall 1, a large space S can be formed at the center of the bracing wall 1 in plan view. The work of carrying out the earth and sand of the ground and the construction of the new building can be carried out efficiently.

[0039] Also, by controlling the axial force N2, the bracing deformation can be controlled and the quality can be improved.

[0040] As described above, the preferred embodiments of the present invention have been described, but the present invention is not limited to these embodiments. Additions, omissions, substitutions, and other changes to the configuration are possible without departing from the spirit of the present invention. The present invention is not limited by the above description, but is limited only by the appended claims.

[0041] In the above embodiment, an earth retaining wall 1 having wall portions 11 arranged along the outer edge of a substantially rectangular shape in plan view has been described as an example, but the present invention is not limited to this. The present invention is applicable to earth retaining walls 1 having various planar shapes as long as they have wall portions 11 arranged opposite each other. For example, the outer edge shape formed by the wall portions 11 may be a circle, a triangle, a polygon, or the like in plan view.

[0042] In the embodiment described above, the struts 4 are arranged diagonally so as to intersect in the long side direction and the short side direction, but this is not limited to this. The struts 4 may be arranged to extend in the long side direction and the short side direction like a normal cross beam, instead of being diagonal beams.

[0043] In the embodiment described above, the strut 4 is installed in one stage, but the present invention is not limited to this. The number of stages of the strut 4 may be set to two or more stages depending on the construction plan, the results of structural calculations, and the like. [Explanation of symbols]

[0044] 1 Mountain retaining wall 2,2a,2b abdominal rise 4 struts 5 Jacking device 100 Mountain retaining structure

Claims

1. This is a retaining method that uses the existing underground structure as a retaining wall. A wale is installed on the retaining wall, and a strut is erected on the plurality of wales, A retaining construction method in which a jack device installed on the strut introduces preload into the existing underground structure.

2. The retaining wall is made up of the existing underground structure, A wale installed on the retaining wall; A strut installed on a plurality of the wales; A retaining structure comprising: a jack device installed on the strut and introducing a preload into the existing underground structure.

3. The retaining structure according to claim 2 , wherein, in a plan view, the strut extends in a direction intersecting the retaining wall.

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