JPH04289330A - Open cut method - Google Patents

Abstract

PURPOSE:To economically perform excavation work for wide range by a method in which underground beams are formed between mutually facing primary trenches constructed on the surrounding of an area to be excavated, a concrete structure is provided in the primary trenches to surround it, and secondary excavation is made. CONSTITUTION:For providing a primary trench 1 in the surrounding of the ground to be excavated, a sheathing wall 2 is constructed before excavation, the bottom ground is improved, and the inside ground is excavated. After the completion of the trenches 1, supporters 3 are horizontally pressed into the counter trench 1 from one trench 1 to form an underground beam. After constructing many underground beams, the ground surrounded by the trenches 1 is reinforced, and a concrete structure is constructed in contact with the sheathing walls 2 from both sides in the trench 1. Finally, the area surrounded by the concrete structure is all excavated secondarily.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an excavation method used when constructing an underground structure by excavating a large area.

0002

BACKGROUND OF THE INVENTION If a wide area is excavated, the surrounding earth and sand will collapse. Therefore, before excavation is carried out, a vertical earth retaining wall is constructed in the ground around the planned excavation area, and cut beams are installed on the earth retaining wall at opposite positions, so that excavation can be carried out while preventing the surrounding area from collapsing. It is common to do so.

0003

[Problems to be Solved by the Invention] In the conventional cut-and-cover construction method described above, it is necessary to improve the ground, especially when construction is performed on soft ground. Therefore, when the area to be excavated is wide, the area of ground to be improved becomes vast, which is extremely uneconomical.

0004

OBJECTS OF THE INVENTION The present invention has been made to solve these problems, and it is an object of the present invention to provide a cut-and-cut method that can economically perform cut-and-cut work over a wide range.

[0005]

[Means for Solving the Problems] The present invention constructs a primary trench on the outer periphery of an area to be excavated, and supports horizontally from one primary trench to the opposite primary trench. An underground beam is formed by pushing the members in, then a concrete structure is constructed inside the primary excavation trench, and a secondary excavation is carried out in the area surrounded by this concrete structure and with horizontal support members pushed underground. This is a trenchless construction method.

[
0006

[Structure of the present invention] The present invention will be explained below with reference to the drawings.

<A> Primary excavation First, a primary excavation groove 1 is encircled around the site where the area is to be excavated. In order to prevent the collapse of this primary excavated groove 1, an earth retaining wall 2 is constructed around it before excavation. As a method for constructing this earth retaining wall, various conventionally known construction methods for underground walls can be employed. Next, the bottom of the primary trench 1 is ground improved 6. This 6 area of ground improvement is sufficient if it is small compared to the planned area of full excavation. Thereafter, with both sides protected by earth retaining walls 2, excavation is performed inside the retaining wall 2, and an open cut trench 1 is constructed.

<B> When the construction of the primary trench 1 is completed on the outer periphery of the area where the underground beam is to be pushed and cut, from one primary trench 1 to the primary trench 1 at the opposite position. An underground beam is formed by pushing the support member 3 horizontally. This horizontal support member 3 can be made of various materials, such as a long concrete block or steel. A large number of these blocks are prepared and pushed into the ground using a jack 7 or the like while sequentially connecting them. This pushing operation can be performed using various known methods such as a thrusting method. The underground beam is completed when the tip of the horizontal support member 3 reaches the primary cut groove at the opposing position. By constructing a large number of these underground beams, the underground area surrounded by the primary trench 1 will be firmly reinforced.

<C> Construction of concrete structure Next, a concrete structure 4 is constructed inside the primary trench. This concrete structure 4 is constructed with both sides in contact with the retaining wall 2. For this purpose, the primary excavation trench 1 will be replaced by a strong structure.

<D> Secondary excavation The enclosing site 5 surrounded by the strong concrete structure 4 is then excavated for a second time. When excavating this enclosing site 5, there is no need to perform internal ground improvement because the preceding underground beam 8 has already been completed. Note that it is safer if a cut beam 9 is provided between the surfaces of the concrete structures 4 on both sides. A predetermined structure is constructed inside the enclosing site 5 excavated in this way.

00011

[Effects of the Invention] Since the present invention is as explained above, the following effects can be obtained. <A> This is a construction method in which cut beams are constructed underground prior to excavation by using the propulsion method. Therefore, the area for ground improvement can be significantly reduced, making it extremely economical. <B> This is a construction method in which a part of the main structure is constructed in advance in the trench of the primary excavation. For this reason, the excavated area is surrounded by a strong concrete structure, allowing for highly safe construction.

[Brief explanation of the drawing]

[Figure 1] Explanatory diagram of construction status

[Figure 2] Explanatory diagram of construction status

[Figure 3] Explanatory diagram of construction status

[Figure 4] Explanatory diagram of construction status

Claims (1)

[Claims] Claim 1: An underground beam is constructed by constructing a primary excavation groove around the outer periphery of the area where excavation is planned, and pushing a support member horizontally from one primary excavation groove toward the primary excavation groove at the opposite position. This is an open-cut construction method in which a concrete structure is built inside the primary trench, and a secondary excavation is performed in the area surrounded by the concrete structure and with horizontal support members pushed underground.