JP2001303883A - Excavation method using earth retaining structure composed of ring beam, inverted lining wall and rock bolt - Google Patents

Abstract

PROBLEM TO BE SOLVED: To safely and inexpensively carry out excavation at the place with an inclined ground surface without using a special construction method or large construction equipment. SOLUTION: The natural ground is vertically excavated by an earth retaining structure composed of a ring-shaped ring beam 2, an inverted lining wall 8, and a rock bolt 6. The ring beam 2 is supported by a ground anchor 4 (or the rock bolt 6). The wall 8 is reinforced with a reinforcing bar 7 (or wire gauze) and constructed out of concrete on the inner-periphery surface of an excavated hole 11 for the purpose of being fixed to the ring beam 2 at each step of excavating the inside of the ring beam 2. The rock bolt 6 is integrated with the wall 8 so as to reinforce the natural ground of an excavated peripheral surface and support the weight of the ring beam 2 and the wall 8. The low-cost and safe excavation can be performed without using the special construction method or the large construction equipment because the inside of the light- weight earth retaining structure with high safety is excavated in a step-by-step manner.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method used for excavation work in a place where the ground surface is inclined, for example, excavation work for a bridge substructure, excavation work for a steel tower foundation, and excavation work for a tunnel ventilation tower.

[0002]

2. Description of the Related Art The following construction methods are well known for excavation work in a place where the ground surface is inclined. One of them is
This is an excavation method using a main pile horizontal sheet pile type retaining wall combined with a ground anchor. This method has the following problems. That is, when the earth retaining pile is set up on the slope on the slope, the cost increases because a general-purpose machine cannot be used. Large construction machinery is indispensable for installing, removing and transporting retaining piles and shoring, and therefore requires a solid footing. When the excavation depth becomes deeper, the number of times of supporting (belly raising) and installation / removal of the ground anchor increases, so that the construction becomes complicated and the cost increases. The gap formed between the horizontal sheet pile and the ground may cause deformation of the back ground. If it is kept as a permanent structure, it may damage the landscape.

[0003] The second is an excavation method using an open cut method with a method. This method requires a large amount of excavated soil, requires a large amount of land, may have a large amount of excavated soil, which may impair the stability of the entire ground, may cause a long artificial slope, and may impair the landscape. There are problems such as maintenance and management costs for slopes.

[0004]

The problem to be solved by the present invention is to reduce the construction cost for the former construction method, not to use a special construction method or a large construction machine, to simplify the construction scaffold, Enables construction with the minimum required area,
The purpose of the present invention is to suppress the ground deformation caused by excavation and to minimize the influence on the landscape. For the latter method, the amount of excavated soil is minimized, construction is possible with the minimum required area, natural destruction and the impact on the landscape are minimized, and maintenance and management costs for artificial slopes To ensure safety during construction.

[0005]

The features of the present invention are as follows. That is, in an excavation work on a place where the ground surface is inclined, a ring beam formed of a ring-shaped reinforced concrete or steel beam supported by a ground anchor or a rock bolt built on the ground surface, In each excavation step of excavating the inside of the beam stepwise to form a drilled hole, it was reinforced with reinforcing steel or wire mesh and built on the inner peripheral surface of the drilled hole by spraying or cast-in-place concrete and fixed to the ring beam Ground excavation is made vertically by a retaining wall structure composed of a reverse winding wall and a rock bolt integrated with the reverse winding wall to support the ground of the excavation surface and to support the weight of the ring beam and the reverse winding wall. I do.

[0006] According to such a construction method, the ring beam is supported by the ground anchor (or the lock bolt) which supports the ring beam. In the case of reinforced concrete, reinforcement is provided by reinforcing bars. Because of the support, horizontal movement of the entire retaining structure can be prevented.

Further, since the reverse winding wall has an arch structure having a large resistance to an external force, the wall thickness can be reduced and an economic retaining wall can be constructed.

Since the weight of the earth retaining structure is supported by the lock bolt integrated with the reverse winding wall, advance excavation is possible, and there is also an effect of reinforcing the ground. Therefore, the earth pressure acting on the reverse winding wall is reduced. It is possible to do.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The excavation method according to the present invention will be described with reference to the drawings showing a case in which a substructure is constructed on a place where the ground surface is inclined. First, as shown in FIGS. 1 to 3, as a ring beam slip prevention work, a lock bolt is mounted at a predetermined position on the ground surface, that is, around an excavation hole 11 to be formed by excavation in order to perform a pier substructure. One group is set up.
When the ring beam slip prevention work is completed, the ring beam 2 is built with reinforced concrete. When assembling the reinforcing bar 3a of the ring beam, a reinforcing bar 3b for fixing a reverse winding wall described later to the ring beam is assembled. Due to the construction of the ring beam, the upper end of the lock bolt 1 is taken into the ring beam, and the lock bolt is integrated with the ring beam. As a result, the planned drilling hole 11 will be surrounded by the ring beam.

Next, as shown in FIGS. 1, 4 and 5, a group of ground anchors 4 (or lock bolts) is installed at a predetermined position of the ring beam 2. When the installation of the ground anchor group is completed, the inside of the ring beam is excavated to an arbitrary depth, usually 0.5 to 2.0 m,
In order to prevent a small collapse of the ground, concrete is sprayed on the inner peripheral surface of the excavation hole 11 with a thickness of about 10 cm to form a primary sprayed concrete wall 5 and a group of rock bolts 6 on the primary sprayed concrete wall. We install and settle and prevent.

[0011] Then, while performing the subsidence prevention work,
Excavation is performed until the excavation depth reaches an arbitrary depth, usually 2 m. After assembling the reinforcing steel 7 (or wire mesh) inside the primary sprayed concrete wall 5, the secondary concrete is formed with a thickness of about 20 to 30 cm. By spraying (or casting in place), the reverse winding wall 8 is formed on the inner peripheral surface of the excavation hole 11. The reverse winding wall is fixed to the ring beam by the reinforcing bar 3b. Steps (1) to (4) are repeated until the scheduled depth of the excavation hole 11 is reached.

When the predetermined depth is reached, an annular bottom cover concrete 9 is built at the lower end of the reverse winding wall 8, and a guide wall 10 is built at the lower end of the inner peripheral surface of the bottom cover concrete. Then, the pier foundation hole 12 is excavated.

[0013]

Since the ring structure has an arch effect, it is a lightweight and highly stable earth retaining structure. In addition, since a large construction machine is not required, a firm scaffold and a large area are not required.

Since no support work is required, the workability and economic efficiency are improved as the excavation depth increases. When a ground anchor is required, the ground anchor can be installed at one time, which further improves the economic efficiency.

Since the earth retaining wall can be built in close contact with the ground, loosening of the ground due to excavation can be suppressed, and since the excavated surface is covered with reinforced concrete, maintenance and management costs can be reduced. In addition, since earth retaining walls are constructed at each excavation stage, safety is high.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating the order of construction.

FIG. 2 is a cross-sectional view of a ring beam subjected to anti-sinking work.

FIG. 3 is a view taken along the line AA of FIG. 2;

FIG. 4 is a sectional view of an earth retaining structure from which a lock bolt for preventing ring beam slippage is omitted.

FIG. 5 is a BB view of FIG. 4;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Lock bolt (for preventing ring beam sliding) 2 Ring beam 4 Ground anchor 6 Lock bolt (for preventing settlement) 8 Reverse winding wall 11 Drilling hole

 ──────────────────────────────────────────────────続 き Continued on the front page F-term (reference) 2D044 AA01 2D046 DA31

Claims (2)

[Claims] 1. A ring beam formed of a ring-shaped reinforced concrete or steel beam supported on a ground anchor or a rock bolt in an excavation work on an inclined ground surface and built on the ground surface. In each excavation step in which the inside of the ring beam is excavated stepwise to form an excavation hole, a reverse winding wall reinforced with reinforcing steel or wire mesh, built with concrete on the inner peripheral surface of the excavation hole, and fixed to the ring beam And excavating the ground vertically by an earth retaining structure composed of rock bolts integrated with the reverse winding wall to support the ground reinforcement on the excavation surface and to support the weight of the ring beam and the reverse winding wall. An excavation method using an earth retaining structure composed of a ring beam, a reverse winding wall, and a lock bolt. 2. A lock bolt integrated with a ring beam is installed in advance at a ring beam installation site in order to prevent the collapse of the ground when excavating vertically and to prevent the ring beam from sliding when the ring beam is installed. An excavation method using an earth retaining structure comprising the ring beam, the reverse winding wall, and the lock bolt according to claim 1.