JPH03293429A - Underground structure and its construction - Google Patents

Abstract

PURPOSE:To form an economical underground structure without the need for foundation piling work by a method in which an outer shell caisson set eccentrically with a central caisson is penetrated by the expanding and contracting action of a press jack to fix an earth anchor to the bottom slab. CONSTITUTION:A central caisson 1 is settled in the bearing stratum 5, concrete is placed to construct a bottom slab 4, and earth anchors 3 reaching the stratum 5 are set inside an outer shell caisson 2 set eccentrically. The upper parts of the anchors 3 are inserted into a press jack set on the caisson 2 and the caisson 2 is penetrated by using the drawing resistance of the anchors 3 in parallel with the expanding and contracting action of the press jack. When they reach a given depth, concrete is placed to the bottom of the caisson 2 to construct a bottom slab 7 and integrally connected to the peripheral side of the caisson 1. The upper ends of the anchors 3 are fixed to the bottom slab 7 and the top plate 8 is constructed, followed by embedding work. The drawing reaction of the anchors 3 is opposed to the floating and rotation moment of structure.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a technique for burying underground structures, and more specifically to underground structures and structures where it is necessary to simultaneously consider the conditions of sinking due to the structure's own weight and increase of buoyancy. Regarding its construction method.

<Prior Art> For example, when designing an underground structure such as an underground multi-storey parking lot, consideration must be given to the subsidence due to the underground structure's own weight and the levitation due to buoyancy.

Specifically, multiple foundation piles built together with the underground structure are used to prevent the underground structure from sinking or rising.

<Problems to be Solved by the Present Invention> The conventional underground structure construction techniques described above have the following problems.

Kui〉　Construction of foundation piles requires a large amount of construction cost.

<Exit> Construction will take a long time as it will be carried out from above ground.

〈C〉 When excavation is carried out by retaining the mountain, a large amount of materials and equipment will be brought in and out, making the construction work complicated.

<Object of the present invention> The present invention has been made in view of the above points, and its purpose is to provide an underground structure that can effectively prevent the underground structure from sinking due to its own weight and rising due to buoyancy. It's about doing.

A further object of the present invention is to provide a method for constructing an underground structure that can reduce foundation construction costs and has excellent workability.

<Means for Solving the Problems> In other words, the present invention provides an underground structure in which the self-weight and buoyancy of the structure must be taken into account at the same time in the design. An underground structure having a support surface that supports the structure's own weight, and an earth anchor for preventing the structure from rotating or floating between the support layer and the underground structure. It is.

Furthermore, in a method of constructing an underground structure in which the weight and buoyancy of the structure must be taken into account at the same time in the design, the central caisson of the bottomed structure is embedded in the support layer and sunk, and the cross section is lower than the central caisson. An outer shell caisson with a large diameter is placed outside the central caisson, an earth anchor is constructed that reaches the supporting layer, the outer shell caisson is press-fitted into the ground while receiving reaction force from the earth anchor, and then the outer shell caisson is This method of constructing an underground structure is characterized by constructing a bottom slab integral with the central caisson at the lower part of the earth anchor, and fixing the upper part of the earth anchor to the bottom slab of the outer shell caisson.

Description of the present invention> The present invention will be described below with reference to the drawings.

<B> Structure of underground structures FIG. 1 shows a vertical cross-sectional view of an underground structure according to the present invention.

This underground structure consists of a central caisson 1 with a bottomed structure, an outer shell caisson 2 with a bottomed structure extending to the sides of the central caisson 1, and a plurality of shells fixed downward from the bottom of the caisson. It consists of earth anchor 3.

In this embodiment, a case will be described in which the space inside the outer shell caisson 2 is partitioned in multiple stages as a car storage room, and the space inside the central caisson 1 is used as an elevator hall or an exhaust hole. 1 and outer shell caisson 2
The internal space of the building shall be divided according to the purpose of use.

Further, the cross-sectional shape and overall shape of the central caisson 1 and the outer shell caisson 2 are not particularly limited, and may be appropriately designed depending on the purpose of use.

<Exposure> Subsidence Prevention Means The underground structure of the present invention basically supports the weight of the underground structure by a part of the structure embedded in the support layer 4, that is, by the bottom slab 4 of the central caisson 1.

Therefore, this bottom plate 4 functions as a dead weight supporting surface, and the bottom plate 5 of the outer shell caisson 2 supports the dead weight of the underground structure auxiliary.

<C> Floating prevention means The present invention counteracts the levitation and rotation moment of the underground structure by utilizing the pull-out reaction force of the earth anchor 3 fixed between the bottom plate of the underground structure and the support layer 5.

<Effect> Next, a method for constructing the underground structure will be explained.

<A> Sinking the central caisson and constructing the bottom slab (Fig. 2) The central caisson 1 with its upper and lower ends open is sunk by a known method.

The central caisson 1 is sunk to a depth until its lower end reaches the support layer 5. Next, a bottom slab 4 is constructed by pouring concrete or the like at the bottom of the central caisson 1.

<Mouth> Press-fitting the outer shell caisson (Fig. 3) Set the outer shell caisson 2 with open upper and lower ends concentrically with the central caisson 1.

Then, a plurality of earth anchors 3 are installed inside the outer shell caisson 2 to reach the support layer 5.

The upper part of each earth anchor 3 is inserted into a center hole type press-fit jack 6 provided in the outer shell caisson 2.

In parallel with the expansion and contraction operation of each press-fitting jack 6, the outer shell caisson 2
The outer shell caisson 2 is press-fitted to a predetermined depth while excavating between the circumferential surfaces of the central caisson 1 and the outer shell caisson 1.

In this way, the outer shell caisson 2 is press-fitted using the pull-out resistance of each earth anchor 3.

It is also possible to partially operate the press-fitting jacks 6 to correct the direction of the outer shell caisson 2.

When the upper end of the outer shell caisson 2 is press-fitted below the ground surface as in this embodiment, it is necessary to provide various temporary retaining walls to prevent the hole wall from collapsing.

<C> Construction of the outer shell bottom slab and fixation of anchors (Fig. 4) After the outer shell caisson 2 is press-fitted to a predetermined depth, concrete is poured into the bottom of the outer shell caisson 2 to construct the bottom slab 7.

As a result, the outer shell caisson 2 is integrally connected to the surface of the central caisson 1 via the bottom plate 7.

Furthermore, the upper end of each earth anchor 3 is fixed to the bottom plate 7,
The pulling reaction force of each earth anchor 3 is used to counter the rotational moment and levitation of the underground structure.

Therefore, each earth anchor 3 functions not only as a source of reaction force when the outer shell caisson 2 is press-fitted, but also as a member for preventing rotation and floating of the underground structure after construction.

Next, after constructing the top plate 8 at the upper mouth of the outer shell caisson 2, backfilling is performed.

<2> Internal construction The partition work in the outer shell caisson 2 may be carried out before the construction of the roof 8, or may be carried out in parallel with the construction of the roof 8 using the central caisson 1.

Finally, the underground structure shown in Figure 1 is completed.

In the underground structure shown in FIG. 1, for example, a space 9 hierarchically divided in the outer shell caisson 2 is used as a parking space, a space 1o in the central caisson 1 is used as an electric heater hall, and a space below the central caisson 1 is used as a parking space. Area 11 can be used as utility facilities such as elevator bits and machine rooms.

<Other Embodiments 1> In the above embodiment, only the bottom plate 4 of the central caisson 1 is embedded in the support layer 5, but the bottom plate 7 of the outer shell caisson 2 is also embedded in the support layer 5, or only the bottom plate 7 is embedded in the support layer 5. It may be based on 5.

Furthermore, an earth anchor 3 for preventing rotation and floating of underground structures may be fixed to the bottom slab 4.

<Other Embodiments 2> In the above embodiments, the case where the central caisson 1 is constructed prior to the construction of the outer shell caisson 2 has been described, but conversely, the outer shell caisson 2 may be constructed prior to construction. .

Effects of the Present Invention> Since the present invention is as explained above, the following effects can be obtained.

By embedding a part of the underground structure in the support layer, the underground structure can support its own weight, and the earth anchor stretched between the structure and the support layer allows the underground structure to rotate and float. can be effectively prevented.

Therefore, there is no need for foundation pile construction as in the past, and an economical underground structure can be obtained.

〉 Earth anchors can be effectively used as a source of reaction force when press-fitting an outer shell caisson, and as a member to prevent rotation and floating of underground structures after construction.

<C> The central caisson can be used as a passageway for carrying in and out various equipment for underground construction.

〈2〉 If the top plate work of the outer shell caisson is completed in advance, the above-ground portion can be opened earlier, so it is possible to open the above-ground part earlier, so it is easier to do so when constructing an underground parking lot or park near the road.
Less obstruction to traffic or impact on third parties.

[Brief explanation of the drawing]

Fig. 1 2 A longitudinal cross-sectional view of the completed underground structure according to the present invention Fig. 2: A longitudinal cross-sectional view of the central caisson when it is sunk Fig. 3: A longitudinal cross-sectional view of the outer shell caisson when it is press-fitted Fig. 4: An earth anchor Longitudinal cross-sectional view when installed in the outer shell caisson

Claims (2)

[Claims] (1) In underground structures where the structure's own weight and buoyancy must be taken into account at the same time in its design, at least a portion of the bottom of the structure should have a support surface that is embedded in the support layer and supports the structure's own weight. An underground structure characterized by having an earth anchor installed between the support layer and the underground structure to prevent the structure from rotating or floating. (2) In the construction method of underground structures, which requires consideration of the structure's own weight and buoyancy at the same time in the design, a central caisson with a bottomed structure is embedded in the support layer and sunk, and the cross section is larger than that of the central caisson. Place the outer shell caisson outside the center caisson, construct an earth anchor that reaches the supporting layer, press fit the outer shell caisson into the ground while receiving reaction force from the earth anchor, and then insert the outer shell caisson at the bottom of the outer shell caisson. A method for constructing an underground structure, comprising constructing a bottom slab integral with a central caisson, and fixing the upper part of the earth anchor to the bottom slab of an outer shell caisson.