JP7184244B2 - Floating control structure and reversed construction method - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lifting suppression structure and a reverse hammering method.

2. Description of the Related Art A measuring method is known for measuring the amount of uplift (uplift) of the ground surrounding an excavation area when excavating the ground (see, for example, Patent Document 1).

Also, there is known a method for constructing an earth retaining wall under an underground structure that is in service (see, for example, Patent Document 2).

JP 2012-082676 A JP-A-8-028197

By the way, when the ground next to the underground structure in service is excavated in a plan view, or the existing underground structure next to the underground structure in service is dismantled, the excavated area or demolished area and the surrounding ground will be damaged. It may float. As a result, the underground structure in service may also be lifted up, and the underground structure in service may be affected.

SUMMARY OF THE INVENTION In view of the above facts, it is an object of the present invention to suppress the uplift of an underground structure during service.

The uplift suppression structure according to the first aspect includes an earth retaining wall adjacent to an in-service underground structure in a plan view, a pile provided along the earth retaining wall and fixed to a support layer of the ground, and the pile and a protruding portion protruding from the outer peripheral surface of the underground structure and located below the center of the in-service underground structure.

According to the uplift suppression structure according to the first aspect , the pile is provided along the retaining wall adjacent to the in-service underground structure in plan view. Also, the piles are fixed to the bearing layer of the ground. The pile is provided with a protrusion. The protruding part protrudes from the outer peripheral surface of the pile and is positioned below the center of the underground structure during service.

As a result, for example, when the ground inside the earth retaining wall, that is, the ground on the opposite side of the earth retaining wall to the underground structure in service, is excavated, the protruding part of the pile will cause the ground to fall below the center of the underground structure in service. Uplift of the ground on the side is suppressed. Therefore, the lifting of the underground structure during service is suppressed.

Also, as mentioned above, the piles are fixed to the bearing layer of the ground. Therefore, lifting of the underground structure during service is further suppressed.

Furthermore, by providing the pile along the retaining wall, the pile can be used as part of the retaining wall. Moreover, by providing the pile along the retaining wall, the pile and retaining wall can be constructed at the same time. Therefore, the workability of the pile is improved.

The uplift suppression structure according to the second aspect includes an earth retaining wall that is adjacent to an in-service underground structure in a plan view, and at least a part of a lower end of which is fixed to a support layer of the ground, and a wall surface of the earth retaining wall. a projecting part that projects and is located below the center of the in-service underground structure.

According to the uplift suppression structure according to the second aspect , the retaining wall is adjacent to the in-service underground structure in a plan view. At least a portion of the lower end of the retaining wall is fixed to the support layer of the ground. Moreover, the retaining wall is provided with a projecting portion. The protruding part protrudes from the wall surface of the retaining wall and is positioned below the center of the underground structure during service.

As a result, for example, when the ground inside the earth retaining wall, that is, the ground on the side opposite to the underground structure in service with respect to the earth retaining wall, is excavated, the projecting part of the earth retaining wall causes Uplift of the ground on the lower side is suppressed. Therefore, the lifting of the underground structure during service is suppressed.

Further, as described above, at least a portion of the lower end of the retaining wall is fixed to the support layer of the ground. Therefore, lifting of the underground structure during service is further suppressed.

Furthermore, by providing the projecting portion on the retaining wall, it is possible to suppress the lifting of the underground structure during use with a simple configuration.

An uplift suppression structure according to a third aspect is the uplift suppression structure according to the first aspect or the second aspect , wherein the protruding portion is arranged around an earth retaining wall side of the in-service underground structure.

According to the uplift suppression structure according to the third aspect , the protruding portion is arranged around the retaining wall side of the in-service underground structure below the center of the in-service underground structure. As a result, lifting of the ground around the retaining wall side of the underground structure in service is suppressed. Therefore, lifting of the underground structure during service is further suppressed.

The reverse construction method according to the fourth aspect is a reverse construction method in which a structure is constructed inside an earth retaining wall adjacent to an in-service underground structure in a plan view, and the earth retaining wall is provided with the in-service underground structure. An enlarged diameter pile that has an enlarged diameter portion located below the center of the object and is arranged along the earth retaining wall, or an enlarged diameter pile that protrudes from the wall surface of the earth retaining wall and extends below the center of the in-service underground structure A suppressing member connects the earth retaining wall provided with the enlarged diameter pile or the projecting part and the structural body of the structure supported by the structural column inside the earth retaining wall. Then, the ground under the structure is excavated while suppressing the uplift of the retaining wall provided with the enlarged diameter pile or the projecting portion by applying a reaction force to the structure.

According to the reverse hammering construction method according to the fourth aspect , the earth retaining wall is provided with the diameter-expansion pile arranged along the earth retaining wall or the protrusion projecting from the wall surface of the earth retaining wall. The enlarged diameter portion of the enlarged diameter pile or the projecting portion of the retaining wall is located below the center of the underground structure during service.

Here, the structural body of the structure is supported by the structural column inside the retaining wall. This structure and the earth retaining wall provided with the enlarged diameter pile or the projecting part are connected by a suppressing member, and the reaction force is applied to the structure to suppress the uplift of the earth retaining wall provided with the enlarged diameter pile or the projecting part. while excavating the ground beneath the structure.

As a result, when the ground under the structure is excavated, uplift of the ground on the side of the underground structure that is in service is suppressed by the diameter-expansion pile or the retaining wall provided with the projecting portion. Therefore, the lifting of the underground structure during service is suppressed.

As described above, according to the present invention, it is possible to suppress the lifting of an underground structure during service.

1 is a longitudinal sectional view showing ground to which an uplift suppression structure according to a first embodiment is applied; FIG. It is a longitudinal cross-sectional view showing a state in which a structure is constructed on the ground to which the uplift suppression structure according to the first embodiment is applied. (A) is a plan sectional view of the mountain retaining wall shown in FIG. 1, and (B) and (C) are plan sectional views showing modifications of the mountain retaining wall shown in FIG. 3(A). It is a perspective view which shows the mountain retaining wall which concerns on 2nd embodiment. It is a longitudinal cross-sectional view showing a structure under construction to which the reverse construction method according to the third embodiment is applied. It is a longitudinal cross-sectional view corresponding to FIG. 5 which shows the modification of the reverse construction method which concerns on 3rd embodiment. FIG. 2 is a vertical cross-sectional view showing a modification of the in-service underground structure shown in FIG. 1;

(First embodiment)
First, the first embodiment will be described.

FIG. 1 shows the ground 12 to which the lifting suppression structure 10 according to this embodiment is applied. An underground structure 16 is provided on the ground 12 during service. The in-service underground structure 16 is, for example, a railroad (subway) or a road in service, and is buried in the ground 12 (underground).

At least a part of the in-service underground structure 16 may be buried in the ground 12 .

(Structure)
As shown in FIG. 2, in this embodiment, a structure 20 is constructed by excavating the ground 12 (excavation area R) adjacent to an in-service underground structure 16 . The structure 20 consists of multiple layers. The structure 20 also includes a plurality of pillars 22 , a plurality of beams 24 extending between adjacent pillars 22 , and a floor slab 26 supported by the beams 24 .

The pillars 22 inside the structure 20 are supported by the structural column piles 21, and the pillars 22 on the outer periphery of the structure 20 are supported by retaining walls 30 and 32, which will be described later.

The structure 20 has an underground structure 20A provided in the ground 12 and an aboveground structure 20B provided above ground. The underground structure 20A is provided in the excavation area R of the ground 12. As shown in FIG. Further, an aboveground structure 20B is provided on the underground structure 20A.

Note that the underground structure 20A and the aboveground structure 20B may be single layers. Moreover, the structure 20 may have at least the underground structure 20A, and the aboveground structure 20B may be omitted. Also, the underground structure 20A and the aboveground structure 20B are examples of structures.

A retaining wall 30 is provided on the outer periphery of the excavation area R of the ground 12 . The retaining wall 30 is formed, for example, in a frame shape in plan view so as to surround the excavation region R. As shown in FIG. Of the earth retaining walls 30, the uplift suppression structure 10 according to the present embodiment is applied to the earth retaining wall 32 on the side of the underground structure 16 in service.

(Lift suppression structure)
The lifting suppression structure 10 includes an earth retaining wall 32 and a diameter expansion pile 40. - 特許庁The earth retaining wall 32 is arranged adjacent to the underground structure 16 in service in plan view. In addition, the retaining wall 32 is arranged to face the underground structure 16 during use.

As shown in FIG. 3(A), the earth retaining wall 32 can be suitably implemented even if it has a plurality of ground improvement bodies (columnar soil improvement bodies) 34 and a plurality of core members 36 . The soil improvement body 34 is formed in a columnar shape from soil cement. A core material 36 is embedded in the soil improvement body 34 .

The core material (steel frame core material) 36 is made of H-shaped steel, for example, and dropped into the ground improvement body 34 before hardening. The core member 36 also has two flange portions 36A and a web portion 36B connecting the two flange portions 36A. The two flange portions 36A are arranged to face each other in the thickness direction (wall thickness direction) of the mountain retaining wall 32 . Out-of-plane rigidity is imparted to the mountain retaining wall 32 by the core material 36 .

The expanded diameter pile 40 is, for example, a cast-in-place concrete pile, and is arranged along the retaining wall 32 . In this embodiment, the diameter-expansion piles 40 and the ground improvement bodies 34 are alternately arranged, and the diameter-expansion piles 40 form part of the retaining wall 32 .

As shown in FIG. 1 , the lower end portion 40L of the diameter expansion pile 40 is fixed to the support layer 14 of the ground 12 . Specifically, the lower end portion 40L of the expanded diameter pile 40 reaches the support layer 14 . A plurality of fixing enlarged diameter portions 42 are provided on the lower end portion 40L side of the enlarged diameter pile 40 .

The plurality of fixed enlarged diameter portions 42 are arranged at intervals in the axial direction (vertical direction) of the enlarged diameter pile 40 . Each enlarged diameter fixing portion 42 is formed by partially enlarging the lower end portion 40</b>L side of the enlarged diameter pile 40 , and protrudes from the outer peripheral surface 40</b>A of the enlarged diameter pile 40 . These fixed enlarged diameter portions 42 resist the pull-out force F acting on the enlarged diameter pile 40 . As a result, lifting of the diameter-expansion pile 40 is suppressed.

In addition, the diameter expansion pile 40 can be provided with at least one fixing diameter expansion portion 42 . In addition, the fixing enlarged diameter portion 42 can be omitted.

The diameter-expansion pile 40 has an upper suppressing enlarged-diameter portion 44 and a lower suppressing enlarged-diameter portion 46 that suppress the uplift of the ground 12 . The upper constraining enlarged diameter portion 44 and the lower constraining enlarged diameter portion 46 are arranged above the support layer 14 . In addition, the upper suppressing enlarged diameter portion 44 and the lower suppressing enlarged diameter portion 46 are arranged above the excavation region R's excavation bottom R1.

The upper constraining enlarged diameter portion 44 and the lower constraining enlarged diameter portion 46 are spaced apart in the axial direction of the enlarged diameter pile 40 . The upper suppressing enlarged diameter portion 44 and the lower suppressing enlarged diameter portion 46 are formed by partially expanding the diameter of the enlarged diameter pile 40 .

The upper suppressing enlarged diameter portion 44 and the lower suppressing enlarged diameter portion 46 are arranged around the earth retaining wall 32 side of the in-service underground structure 16 in a vertical cross-sectional view (upright cross-sectional view). In addition, the upper suppressing enlarged diameter portion 44 is arranged above the center C of the in-service underground structure 16 . On the other hand, the lower suppressing enlarged diameter portion 46 is arranged below the center C of the in-service underground structure 16 . Uplift of the ground 12 around the in-service underground structure 16 is suppressed by the upper suppressing enlarged diameter portion 44 and the lower suppressing enlarged diameter portion 46 .

In addition, the lower suppressing enlarged diameter portion 46 is an example of a projecting portion. In addition, the surroundings of the underground structure 16 in service means, for example, the degree of proximity according to the guidelines adhered to by the owner or manager of the underground structure 16 in service, and the "restricted range (▲ 3 ▼)” or the like, or a case of “close mountain stop” or the like when viewed from the new structure (structure 20).

“Limited range (3)” is the range where the construction of a new structure is considered to have harmful effects on existing structures such as displacement and deformation (“Construction of adjacent urban railway structures countermeasure manual” p.24, p.68, Figure 3.6.6, Table 3.6.3, Railway Technical Research Institute, published in January 2007).

In addition, for "adjacent earth retaining", it is considered to set a permissible value for the amount of displacement of the earth retaining wall or the amount of inclination/displacement of the adjacent structure at the time of planning the earth retaining wall so as not to have a harmful effect on the adjacent structure. This is the case (“Earth stop design guidelines” p.64, p.67, Figure 3.6.1, Table 3.6.1, Architectural Institute of Japan, November 2017 issue).

(Construction method of lifting control structure)
Next, the effect of this embodiment will be described while describing an example of the construction method of the lifting suppression structure 10 .

First, a frame-shaped retaining wall 30 is constructed along the outer periphery of the excavation area R of the ground 12 . At this time, a plurality of expanded diameter piles 40 are constructed along the earth retaining wall 32 of the earth retaining wall 30 on the side of the underground structure 16 in service.

Next, as shown in FIG. 1, an excavation area R inside the earth retaining wall 32 is excavated on the opposite side of the earth retaining wall 32 from the underground structure 16 in service.

Here, as indicated by the chain double-dashed line L1 in FIG. 1, when excavating the excavation region R of the ground 12, there is a possibility that the excavation bottom R1 of the excavation region R and the surrounding ground 12 will rise. If the ground 12 around the excavation area R rises, the underground structure 16 may rise during use.

As a countermeasure against this, in this embodiment, a plurality of diameter-expansion piles 40 are provided on the retaining wall 32 on the side of the underground structure 16 in service. A plurality of diameter-expansion piles 40 are arranged along the retaining wall 32 , and their lower ends 40L are fixed to the support layer 14 of the ground 12 . Each diameter expansion pile 40 is provided with an upper suppressing enlarged diameter portion 44 and a lower suppressing enlarged diameter portion 46304C.

The lower suppressing enlarged diameter portion 46 is arranged below the center C of the in-service underground structure 16 and around the retaining wall 32 side of the in-service underground structure 16 . As a result, when the excavation region R of the ground 12 is excavated, as indicated by the two-dot chain line L2 in FIG. Uplift of the ground 12 is suppressed. Therefore, the floating of the underground structure 16 during service is suppressed.

Furthermore, the upper suppressing enlarged diameter portion 44 is arranged above the center C of the underground structure 16 in service and around the retaining wall 32 side of the underground structure 16 in service. As a result, when the excavation region R of the ground 12 is excavated, the upper suppressing enlarged diameter portion 44 suppresses the lifting of the ground 12 above the center C of the in-service underground structure 16 . Therefore, the lifting of the underground structure 16 during service is further suppressed.

Moreover, by arranging a plurality of diameter-expansion piles 40 along the earth retaining wall 32 , these diameter-expansion piles 40 can be used as part of the earth retaining wall 32 . Furthermore, by arranging a plurality of diameter-expansion piles 40 along the mountain retaining wall 32, the diameter-expanding piles 40 and the mountain retaining wall 32 can be constructed at the same time. Therefore, the workability of the diameter expansion pile 40 and the retaining wall 32 is improved.

(Modification of first embodiment)
Next, a modified example of the first embodiment will be described.

As shown in FIG. 3A, in the above-described embodiment, the soil improvement bodies 34 and the diameter-expansion piles 40 are alternately arranged, but the above-described embodiment is not limited to this. The number of diameter-expansion piles 40 can be changed as appropriate. For example, as shown in FIG. You can set it.

Moreover, the size of the diameter expansion pile 40 can be changed as appropriate, and for example, as shown in FIG.

3(B) and 3(C), the retaining wall 52 may be a composite wall of the soil improvement body 34 and the reinforced concrete wall 54. As shown in FIGS. In addition, in the earth retaining wall 52, a plurality of studs 56 are provided on the flange portion 36A of the core material 36, and by embedding these studs 56 in the reinforced concrete wall 54, the ground improvement body 34 and the reinforced concrete wall 54 are integrated. is raised.

Further, in the above embodiment, the upper suppressing enlarged diameter portion 44 and the lower suppressing enlarged diameter portion 46 are arranged around the retaining wall 32 side of the underground structure 16 in service. However, the upper suppressing enlarged diameter portion 44 and the lower suppressing enlarged diameter portion 46 may be arranged outside the circumference of the in-service underground structure 16 on the premise that the suppressing effect can be exhibited.

Further, in the above-described embodiment, the diameter-expanded pile 40 is provided with the upper suppressing enlarged-diameter portion 44, but the above-described embodiment is not limited to this. The upper suppressing enlarged diameter portion 44 can be omitted.

Moreover, in the above-described embodiment, the retaining wall 32 is formed of the ground improvement body (soil cement) 34, but the above-described embodiment is not limited to this. The mountain retaining wall 32 may be formed of, for example, a reinforced concrete wall or a steel wall.

Moreover, the pile (expansion pile) is not limited to a cast-in-place pile, and may be an existing pile. Moreover, the pile (expansion pile) is not limited to a concrete pile, and may be a steel pile.

(Second embodiment)
Next, a second embodiment will be described. In addition, in the second embodiment, members having the same configuration as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted as appropriate.

As shown in FIG. 4 , the uplift suppression structure 60 according to the second embodiment includes mountain retaining walls 62 . Like the earth retaining wall 32 (see FIG. 1) in the first embodiment, the earth retaining wall 62 is adjacent to the in-service underground structure 16 (see FIG. 1) in a plan view, and is adjacent to the in-service underground structure 16. They are arranged facing each other. That is, the mountain retaining wall 62 is arranged at the same position as the mountain retaining wall 32 shown in FIG. 1, for example.

The mountain retaining wall 62 has a wall body portion 64 and a plurality of fixing extension portions 66 . The wall body 64 is a diaphragm wall made of reinforced concrete. A plurality of fixing extensions 66 are provided at the lower end of the wall main body 64 .

The plurality of fixing extensions 66 are formed in the shape of columns or walls, for example, from reinforced concrete or the like. Each fixing extension 66 reaches the support layer 14 (see FIG. 1) of the ground 12 and is fixed to the support layer 14 . As a result, lifting of the retaining wall 62 is suppressed.

Note that the fixing extension portion 66 may be provided with an enlarged diameter portion or the like fixed to the support layer 14 . Also, the fixing extension 66 is an example of a part of the lower end of the retaining wall 62 .

Here, the wall body portion 64 is provided with an upper suppressing protrusion 68 and a lower suppressing protrusion 70 . The upper suppressing protrusion 68 and the lower suppressing protrusion 70 are arranged with an interval therebetween in the vertical direction. Moreover, each of the upper suppressing protrusions 68 and the lower suppressing protrusions 70 extends in the lateral width direction of the wall main body 64 and protrudes from the wall surfaces 64A and 64B on both sides of the wall main body 64 .

The upper suppressing protruding portion 68 and the lower suppressing protruding portion 70 are similar to the upper suppressing enlarged diameter portion 44 and the lower suppressing enlarged diameter portion 46 (see FIG. 1) of the first embodiment described above. placed around. In addition, the upper suppressing projecting portion 68 is arranged above the center C of the underground structure 16 in service. On the other hand, the lower suppressing projecting portion 70 is arranged below the center C of the underground structure 16 in service. Uplift of the ground 12 around the underground structure 16 during service is suppressed by these upper suppressing projecting portion 68 and lower suppressing projecting portion 70 . Note that the lower suppressing projecting portion 70 is an example of a projecting portion.

(Construction method of lifting control structure)
Next, the effects of the present embodiment will be described while describing an example of a construction method for the lifting suppression structure 60 .

First, a frame-shaped retaining wall (not shown) is constructed along the outer periphery of the excavated area R of the ground 12 . At this time, an upper suppressing projecting portion 68 and a lower suppressing projecting portion 70 are formed on the retaining wall 62 on the side of the underground structure 16 that is in service among the retaining walls 62 .

Next, an excavation area R inside the retaining wall 62 is excavated.

Here, a plurality of fixing extensions 66 are provided on the retaining wall 62 on the side of the underground structure 16 that is in service. The fixing extension 66 is fixed to the support layer 14 of the ground 12 . As a result, the mountain retaining wall 62 is prevented from being lifted when a pulling force acts on the mountain retaining wall 62 .

Further, the wall main body portion 64 of the mountain retaining wall 62 is provided with an upper restraining projection portion 68 and a lower restraining projection portion 70 . The lower suppressing protrusions 70 protrude from the wall surfaces 64A and 64B on both sides of the wall body portion 64 . The lower suppressing projecting portion 70 is arranged below the center C of the underground structure 16 that is in service.

As a result, when the excavation area R inside the retaining wall 62 is excavated, the ground 12 below the center C of the underground structure 16 in service is suppressed by the lower suppressing projecting portion 70 of the retaining wall 62. be done. Therefore, the floating of the underground structure 16 during service is suppressed.

Further, the wall body portion 64 of the retaining wall 62 is provided with an upper restraining projection portion 68 . The upper suppressing protrusions 68 protrude from the wall surfaces 64A and 64B on both sides of the wall body portion 64 . This upper suppressing projecting portion 68 is arranged above the center C of the underground structure 16 during service.

As a result, when the excavation region R of the ground 12 is excavated, the ground 12 above the center C of the in-service underground structure 16 is suppressed by the upper suppressing projecting portion 68 of the retaining wall 62 . Therefore, the lifting of the underground structure 16 during service is further suppressed.

Further, the upper restraining protrusion 68 and the lower restraining protrusion 70 are arranged around the retaining wall 32 side of the underground structure 16 during service. As a result, when the excavation region R of the ground 12 is excavated, the uplift of the ground 12 around the retaining wall 32 side of the underground structure 16 in service is suppressed. Therefore, the lifting of the underground structure 16 during service is further suppressed.

Furthermore, by providing the upper suppressing protrusion 68 and the lower suppressing protrusion 70 on the wall main body 64 of the retaining wall 62, it is possible to suppress the floating of the underground structure 16 during service with a simple configuration.

(Modified example of the second embodiment)
Next, a modified example of the second embodiment will be described.

In the above embodiment, the upper restraining protrusion 68 and the lower restraining protrusion 70 extend in the width direction of the mountain retaining wall 62, but the above embodiment is not limited to this. The upper restraining protrusion and the lower restraining protrusion may be formed in block shapes, for example.

Further, in the above embodiment, the upper suppressing protrusion 68 and the lower suppressing protrusion 70 are provided on the wall surfaces 64A and 64B on both sides of the wall main body 64, but the above embodiment is not limited to this. The upper suppressing protrusion and the lower suppressing protrusion may be provided only on the wall surface 64A or the wall surface 64B of the wall body portion 64, for example. In addition, it is desirable that the upper suppressing projecting portion 68 and the lower suppressing projecting portion 70 are provided at least on the wall surface 64A of the wall body portion 64 on the side of the in-service underground structure 16 .

Further, in the above-described embodiment, the upper restraining projecting portion 68 and the lower restraining projecting portion 70 are arranged around the retaining wall 32 side of the underground structure 16 in service. However, the upper suppressing projecting portion 68 and the lower suppressing projecting portion 70 may be arranged outside the periphery of the in-service underground structure 16 on the premise that the suppressing effect can be exhibited.

Further, in the above-described embodiment, the mountain retaining wall 62 is provided with the upper suppressing protrusion 68 and the lower suppressing protrusion 70, but the above-described embodiment is not limited to this. The upper restraining protrusion 68 can be omitted.

Further, in the above embodiment, the fixing extension portion 66 of the earth retaining wall 62 is fixed to the support layer 14 of the ground 12, but the above embodiment is not limited to this. For example, the mountain retaining wall 62 (wall body portion 64 ) may be formed so that the entire lower end thereof reaches the support layer 14 . That is, at least a part of the lower end of the retaining wall 62 should be fixed to the support layer 14 of the ground 12 . Also, the fixing extension 66 can be omitted.

(Third embodiment)
Next, a third embodiment will be described. In addition, in the third embodiment, members having the same configuration as those in the first embodiment and the second embodiment are denoted by the same reference numerals, and description thereof is omitted as appropriate.

In the third embodiment, as shown in FIG. 5, the structure 20 is constructed by the reverse construction method. At this time, by connecting the diameter-expansion pile 80 and the structure 20 with a temporary diagonal beam 84, the diameter-expansion pile 80 is prevented from rising. Note that the temporary diagonal beam 84 is an example of a suppressing member.

Specifically, first, the retaining wall 30 is constructed along the outer periphery of the excavation area R of the ground 12 . At this time, a diameter expansion pile 80 is constructed along the retaining wall 32 on the side of the underground structure 16 in service. In addition, the lower end portion of the expanded diameter pile 80 of the present embodiment does not reach the support layer 14 of the ground 12 and is not fixed to the support layer 14 .

Next, a plurality of piles 21 for framing columns are constructed below the excavation bottom R1 of the excavated region R, and a pillar 22 is driven on each pile 21 for framing columns.

Next, the excavation area R is excavated to a predetermined depth (primary excavation). Next, the first floor beam 24 and the floor slab 26 of the structure 20 (ground structure 20B) are constructed. Note that the beams 24 and floor slabs 26 of the first floor of the structure 20 are supported by a plurality of structural columns (pillars) 22 . Also, the first floor beams 24 and floor slabs 26 of the structure 20 function as earth retaining shoring supporting earth retaining walls 30 and 32 .

Next, the excavation area R is excavated (secondary excavation) to a predetermined depth, and the underground structure 20A is sequentially constructed. In parallel with construction of the underground structure 20A, the aboveground structure 20B is constructed sequentially. Specifically, the columns 22 of the first floor of the ground structure 20B are constructed on the plurality of structure columns 22, and the beams 24 and the floor slabs 26 of the second floor of the ground structure 20B are constructed.

Next, a temporary diagonal beam 84 is obliquely installed between the beam 24 of the second floor of the ground structure 20B and the pile head 80H of the diameter expansion pile 80, and the temporary diagonal beam 84 is used to connect the beam 24 of the second floor and the diameter expansion pile 80. Head 80H is connected. The temporary diagonal beam 84 is provided with a jack 86 for expanding and contracting the temporary diagonal beam 84 .

Next, the ground 12 under the underground structure 20A is excavated to the excavated bottom R1 (see FIG. 2) while the second floor beam 24 and the pile head portion 80H of the expanded diameter pile 80 are connected by the temporary diagonal beam 84. (Tertiary excavation), and the underground structure 20A is sequentially constructed up to the lowest floor. In parallel with construction of the underground structure 20A, the aboveground structure 20B is constructed sequentially. After that, the temporary diagonal beam 84 is removed. The temporary diagonal beams 84 are preferably removed after the underground structure 20A is constructed to the lowest floor.

Here, if the excavated area R is gradually excavated, the excavated area R and the ground 12 around it may rise. If the ground 12 around the excavation area R rises, the underground structure 16 may rise during use.

On the other hand, this embodiment constructs the structure 20 by a reverse construction method, as mentioned above. As a result, the weight of the underground structure 20A and aboveground structure 20B that have already been constructed suppresses lifting of the excavation region R and the surrounding ground 12 .

Further, the diameter-expansion pile 80 is provided with the upper suppressing enlarged-diameter portion 44 and the lower suppressing enlarged-diameter portion 46 in the same manner as in the first embodiment. These upper suppressing enlarged diameter portion 44 and lower suppressing enlarged diameter portion 46 suppress lifting of the ground 12 on the retaining wall 30 side of the underground structure 16 in service.

Furthermore, in the present embodiment, the ground 12 under the underground structure 20A is excavated while the aboveground structure 20B and the diameter expansion pile 80 are connected by the temporary diagonal beam 84 . More specifically, the underground structure 20A is constructed in a state in which the beams 24 of the second floor of the aboveground structure 20B supported by the structure columns 22 and the pile heads 80H of the diameter expansion piles 80 are connected by the temporary diagonal beams 84. Excavate the ground 12 under the .

As a result, when the enlarged diameter pile 80 tries to rise, the temporary diagonal beam 84 applies reaction force to the ground structure 20B to suppress the enlarged diameter pile 80 from rising. Therefore, lifting of the ground 12 on the earth retaining wall 30 side of the underground structure 16 in service is further suppressed.

A jack 86 is provided on the temporary diagonal beam 84 . Therefore, for example, by operating the jacks 86 according to the floating amount of the diameter expansion pile 80 and extending the temporary diagonal beam 84, the lifting of the diameter expansion pile 80 can be efficiently suppressed.

Moreover, since the temporary oblique beam 84 suppresses the uplift of the diameter-expansion pile 80 , it is not necessary to fix the lower end portion of the diameter-expansion pile 80 to the support layer 14 . Therefore, the construction man-hours for the diameter-expansion pile 80 can be reduced.

(Modified example of the third embodiment)
Next, a modified example of the third embodiment will be described.

In the above embodiment, the pile head portion 80H of the expanded diameter pile 80 and the ground structure 20B of the structure 20 are connected by the temporary oblique beam 84, but the above embodiment is not limited to this. For example, as shown in FIG. 6, a portion 80P below the pile head portion 80H of the expanded pile 80 and the underground structure 20A and the aboveground structure 20B may be connected by temporary diagonal beams 84, respectively. .

Further, although the diameter-expansion pile 80 is not fixed to the support layer 14 in the above embodiment, the diameter-expansion pile 80 may be fixed to the support layer 14 .

Also, in the above embodiment, the temporary diagonal beam 84 is provided with the jack 86, but the jack 86 can be omitted as appropriate. Further, the suppressing member is not limited to the temporary diagonal beam 84, and may be another member, for example.

Moreover, the above-described embodiment can also be applied to the retaining wall 62 (see FIG. 4) of the above-described second embodiment. In other words, it is possible to excavate the ground 12 under the underground structure 20A while the retaining wall 62 and the aboveground structure 20B of the structure 20 are connected by the temporary diagonal beam 84. FIG.

(Modified example of the first to third embodiments)
Next, modified examples of the first to third embodiments will be described. Various modifications will be described below using the first embodiment as an example, but these modifications can also be applied to the second embodiment and the third embodiment as appropriate.

In addition, in the first embodiment, the in-service underground structure 16 is positioned above the pruning bottom R1 of the excavation area R, but the embodiment is not limited to this. For example, as shown in FIG. 7, the in-service underground structure 16 may be located below the excavated area R's excavation bottom R1. In this case also, by arranging the upper suppressing enlarged diameter portion 44 and the lower suppressing enlarged diameter portion 46 around the retaining wall 32 side of the underground structure 16 in service, the lifting of the underground structure 16 in service can be effectively prevented. can be suppressed.

Further, in the first embodiment, the excavation area R adjacent to the in-service underground structure 16 is excavated, but the embodiment is not limited to this. The above embodiment can also be applied, for example, when dismantling an existing underground structure (existing underground structure) next to the in-service underground structure 16 .

Although one embodiment of the present invention has been described above, the present invention is not limited to such an embodiment, and one embodiment and various modifications may be used in combination as appropriate. It goes without saying that various aspects can be implemented without departing from the scope.

10 Uplift suppression structure 12 Ground 14 Support layer 16 In-service underground structure 32 Retaining wall 40 Expansion pile (pile)
40A outer peripheral surface (outer peripheral surface of pile)
46 Lower suppression enlarged diameter portion (protruding portion)
50 diameter expansion pile (pile)
52 Mountain retaining wall 60 Lifting suppression structure 62 Mountain retaining wall 64A Wall surface (wall surface of mountain retaining wall)
64B wall surface (wall surface of retaining wall)
66 Fixing extension (a part of the lower end of the retaining wall)
70 Lower suppression projection (projection)
80 diameter expansion pile (pile)
84 Temporary diagonal beam (restraining member)
Center C (center of underground structure in service)

Claims (5)

A retaining wall adjacent to an in-service underground structure in a plan view,
a pile that is provided along the earth retaining wall, constitutes a part of the earth retaining wall, extends downward from the earth retaining wall, and is fixed to the support layer of the ground;
a protruding portion protruding from the outer peripheral surface of the pile;
with
The protrusions are provided below and above the center of the in-service underground structure, respectively.
Floating suppression structure. An earth retaining wall having a wall main body adjacent to an in-service underground structure in a plan view, and a plurality of fixing extensions extending downward from a lower end of the wall main body and fixed to a support layer of the ground. wall and
a protruding portion protruding from the wall surface of the wall body portion ;
with
The protrusions are provided below and above the center of the in-service underground structure, respectively.
Floating suppression structure. The projecting portion is arranged around the retaining wall side of the in-service underground structure,
The floating suppression structure according to claim 1 or 2. A reverse construction method for constructing a structure on the inside of a retaining wall adjacent to an in-service underground structure in plan view,
The retaining wall has a lower suppressing enlarged diameter portion positioned below the center of the underground structure in service, an upper suppressing enlarged diameter portion positioned above the center of the underground structure in service, a diameter-expanding pile arranged along the mountain retaining wall to form a part of the mountain retaining wall and extending downward from the mountain retaining wall ;
The mountain retaining wall and the structural body of the structure supported by the structural column inside the mountain retaining wall are connected by a suppressing member, and a reaction force is applied to the structure to suppress the lifting of the mountain retaining wall. excavating the ground beneath the structure while
Reverse method. A reverse construction method for constructing a structure on the inside of a retaining wall adjacent to an in-service underground structure in plan view,
The earth retaining wall includes a wall main body portion adjacent to the in-service underground structure in a plan view, and a plurality of fixing extensions extending downward from a lower end portion of the wall main body portion and fixed to the support layer of the ground. a lower suppressing projecting portion projecting from the wall surface of the wall main body portion and positioned below the center of the in-service underground structure; and an upper restraining protrusion located on the upper side of the
The mountain retaining wall and the structural body of the structure supported by the structural column inside the mountain retaining wall are connected by a suppressing member, and a reaction force is applied to the structure to suppress the lifting of the mountain retaining wall. excavating the ground beneath the structure;
Reverse method.

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