JPH0146648B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to an underground excavation method for excavating, for example, a subway tunnel or underground of a structure.

(b) Prior Art Conventionally, this type of underground excavation method involves constructing a retaining wall around the area to be excavated, and excavating the inside of the retaining wall, which is exposed by the excavation. Generally, construction is carried out in a step-by-step manner while supported by shoring, but if the ground in the planned excavation area is soft, it is necessary to avoid inward deformation of the retaining wall due to earth pressure, etc. In order to prevent this, a large number of shorings are required, and the work of erecting the shorings is troublesome, and the presence of such a large number of shorings restricts the movement of construction machines such as bulldozers within the planned excavation area. The work is difficult to do, and even if a large number of supports are used, deformation of the retaining wall occurs before the shoring is erected, causing ground subsidence and horizontal movement in the area around the planned excavation area, that is, the ground outside the retaining wall. It has the disadvantage of causing a situation that causes a problem.

In addition, to solve this problem, as shown in FIGS. 9 and 10, prior to excavating the area b to be excavated inside the retaining wall a, the depth is measured over the entire horizontal plane of the area b to be excavated. Preliminary underground temporary floors c are provided at appropriate intervals in the direction, and while reinforcing the retaining wall a with the underground temporary floors c, the inside of the retaining wall a is sequentially excavated along with the underground temporary floor c. A preliminary underground bed construction method is known, but it takes time and effort to provide sequentially layered preliminary underground temporary beds c at appropriate intervals in the depth direction over the entire horizontal plane of the planned excavation area b. In addition, since the underground temporary floor c is discontinuous in the depth direction, there is a disadvantage that a large stress change occurs in the retaining wall a when the underground temporary floor c is excavated.

(c) Purpose of the Invention The present invention solves the disadvantages of the conventional underground excavation method, and even if the ground in the planned excavation area is soft, it does not require a large number of shorings and the work is efficient. It is an object of the present invention to provide an underground excavation method that can excavate the planned excavation area while suppressing the deformation of the retaining wall and minimizing the influence on the surrounding ground.

(d) Structure of the Invention The underground excavation method of the present invention involves constructing a retaining wall around the planned excavation area, excavating inside the retaining wall, and shoring the retaining wall exposed by the excavation. In an underground excavation method in which the excavation is progressed sequentially while being supported by the retaining walls, prior to excavation inside the retaining walls, underground temporary walls made of soil cement are installed between appropriate retaining walls, and the temporary walls are used to The present invention is characterized in that the inner side of the retaining wall is sequentially excavated along with the temporary wall while reinforcing the retaining wall.

(e) Embodiments Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

The illustrated embodiment is one in which the underground excavation method of the present invention is applied to excavation underground of a structure.

First, as shown in FIGS. 1 and 2, a retaining wall 2 is constructed using H-shaped steel piles, sheet piles, etc. around a planned excavation area 1 having a substantially rectangular cross section, and the planned excavation area 1 is divided from its surroundings. do.

Next, as shown in FIGS. 3 and 4, an underground temporary wall 3 made of soil cement is installed, for example, between the opposing long sides of the retaining wall 2. As described below, the underground temporary wall 3 made of soil cement has the strength to adequately reinforce the retaining wall 2, and also has the strength to adequately reinforce the retaining wall 2.
It can be easily excavated together with this when excavating the inside.

The underground temporary wall 3 is constructed by continuously arranging soil-cement piles in a row, which are formed by pouring cement into a hole excavated by an earth auger or the like and mixing it with excavated earth and sand. Do by doing.

Next, as shown in FIGS. 5 and 6, the inside of the retaining wall 2 is excavated one after another, and the retaining wall 2 whose inner side has not been excavated is reinforced with the temporary wall 3.
While supporting the retaining wall 2 exposed by the excavation with shoring 6 such as struts 4 and uprights 5, the inside of the retaining wall 2 is further excavated along with the temporary wall 3, and this work is repeated in sequence. Excavation of planned excavation area 1 is completed.

In the above embodiment, only one underground temporary wall 3 made of soil cement was provided between the opposing long sides of the retaining wall 2, but depending on the ground condition of the planned excavation area 1, for example, 7. As shown in the figure, two underground temporary walls 3 are installed between the opposing long sides of the retaining wall 2.
, or provide one underground temporary wall 3 between the opposing long sides and short sides of the retaining wall 2, or provide an underground temporary wall 3 at an appropriate position of the retaining wall 2. be able to.

(f) Effect of the Invention As described above, according to the present invention, prior to excavating the inside of the retaining wall, an underground temporary wall made of soil cement is installed between appropriate retaining walls, and the temporary wall is used to prevent the mountain from being excavated. In order to excavate the inside of the retaining wall sequentially together with the temporary wall while reinforcing the retaining wall, even if the inside of the retaining wall is excavated, the retaining wall that is not exposed by the excavation below is Since it is always well reinforced with underground temporary walls, the strength of the entire retaining wall against earth pressure is high, and therefore there is less need for shoring to support the retaining wall exposed by excavation, and it is possible to reduce the need for shoring. Even before construction, deformation of the retaining wall can be suppressed to minimize the impact on the surrounding ground, and since the underground temporary wall is excavated at the same time as the excavation inside the retaining wall, the subsequent excavation work will be easier. Not only does it have the effect of allowing efficient underground excavation without getting in the way, but since the underground temporary wall is continuous throughout the depth direction of the planned excavation area, excavation of the underground temporary wall is easy. In some cases, stress changes do not occur in the retaining wall as in previous underground floor construction methods, and the underground temporary wall is installed at a desired location in the planned excavation area to a desired depth from the ground, such as by constructing a soil-cement pile. Compared to the previous underground floor construction method, which involves the construction of a complicated preliminary underground temporary floor that is discontinuous in the depth direction and continuous in the horizontal plane, , safety, and ease of construction.

[Brief explanation of drawings]

Figures 1 to 6 show one of the underground excavation methods of the present invention.
Embodiments are shown in which Fig. 1 is a plan view showing the construction state of the wall stopper, Fig. 2 is a cross-sectional view taken along the line -
Figure 3 is a plan view showing the construction status of the underground temporary construction method;
Fig. 4 is a sectional view taken along the - line, Fig. 5 is a plan view showing the completed state of excavation, Fig. 6 is a sectional view taken along the - line, and Figs. 7 and 8 are modifications of the underground excavation method of the present invention. FIG. 9 is a cut-away plan view showing the state of construction of a preliminary underground temporary floor using the conventional advance underground floor construction method, and FIG. 10 is a cut-away side view thereof. 1... Area to be excavated, 2... Mountain retaining wall, 3...
Underground temporary wall, 6... shoring.

Claims (1)

[Claims] 1. An underground excavation method in which a retaining wall is constructed around the planned excavation area, and excavation inside the retaining wall is progressed sequentially while supporting the retaining wall exposed by the excavation with shoring. Before excavating the inside of the retaining walls, underground temporary walls made of soil cement are installed between appropriate retaining walls, and while reinforcing the retaining walls with the temporary walls, the retaining walls are An underground excavation method characterized by sequentially excavating the inner side together with the temporary wall.