JPS5918900A - Method of construction of backing injection in method of shield construction - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a backfill injection method in a shield construction method.

When a shield machine is used to perform the primary lining of a /-rud tunnel, when the /-rud machine is moved forward, a tail void is created behind the shield machine due to the difference between the outer diameter of the /-rud machine and the segment outer diameter.

This tail void is filled with spring water and muddy water that has circulated from the face, but it does not reach the point where a muddy wall is formed.In highly collapsible ground, collapse or skin fall occurs, and the natural water pressure of the ground is reduced. If the height is high, muddy water containing earth and sand may gush out even inside the shield machine sealed by the tail packing through the small gaps created between the four parts of the segment joints and the tail packing.

In order to prevent these phenomena, conventionally, the collapse of the ground and the fixation of the segments have been achieved by immediately injecting backfilling material such as mortar or chemical into the tail void and solidifying it.

However, in order to perform backfill injection using this method, it is necessary to bring the injection position of the backfill phase to the closest part of the tail packing that soles between the /-rudo machine and segment 7. There is a drawback that backing materials such as mortar and chemicals flow into the mold machine through the gap between the tail packing and the segment, reducing work efficiency.

In addition, in this case, it solidifies between the tail gaskets installed in two or three tiers, impairing the flexibility of the gaskets,
This will reduce the sealing effect and significantly shorten the life of the tail gasket. Furthermore, in the muddy water pressurizing type shield machine, the deterioration of the muddy water is stopped by mixing the backing material during excavation of the face.

In order to deal with these phenomena, it is necessary to perform backfill injection from a certain distance from the shield machine, but in the case of a fine sand layer with high natural water pressure and high collapsibility in the excavated ground, the tail void may collapse. Then, the fluidized fine sand is ejected into the machine through the gap between the recess between the segment joints and the tail packing, and some of it is accumulated and compressed on the back side of the tail packing, which has multiple crotches. forms a wedge-shaped sand camber. This sand camber acts in the same way as the back fill solidified on the back fill of the tail packing, and presses the tail packing against the segment with excessive force, resulting in destruction of the tail packing.

Therefore, in the conventional LDO method, only negative solutions to the above problem were taken, such as increasing the strength of the tail packing.

Therefore, the present invention has been made to eliminate the drawbacks of the conventional methods, and it prevents the collapse of the ground and the intrusion of earth and sand into the /-rud machine in the /-rud construction method, and prevents damage to the tail packing. The purpose is to prevent

In other words, the feature of the backfilling method in the 7-Rudo method of the present invention is that when a shield machine is used to perform the primary lining of the N'Rudo tunnel, a tail void created by the forward movement of the shield machine is provided in the segment. After injecting highly viscous and highly concentrated muddy water through the grout hole, solidifying materials such as mortar and chemicals are injected back into the grout hole to fix the segments.

An embodiment of the present invention will be described below with reference to the drawings, and FIG. 1 is a schematic sectional view of the /-rud construction method in the embodiment of the present invention.

First, as the shield machine 2 excavates the ground 1, a tail void 5 is generated.

Highly concentrated mud water is injected into this tail void 5 from the primary backfilling injection grout hose 11 attached to the segment 6 located close to the shield machine 2 - the next backfilling injection grout hole 9, and then the -next backfilling injection 7 is carried out. Let's do it.

As a result, at the boundary between the tail void 5 and the ground 1,
A muddy water wall is formed, and collapse and skin fall of the ground 1 are avoided.

The small gap between the tail packing 4 and the segment 6 attached to the Rudo machine 2 is also sludged by this highly concentrated muddy water, and the muddy water containing earth and sand is washed away.
It can also prevent inflow into the interior.

This secondary backfill injection 7 is carried out during the excavation of the shield machine 2, but at the same time, via the secondary backfill injection grout hose 12 attached to the segment 6 at a certain distance from the shield machine 2, Grout hole 10 for secondary backfill injection
A secondary backfilling injection 8 is performed by injecting an assimilative material such as mortar or chemical solution, and the segment 6 is fixed underground.

Next, to explain the situation in an example in which this 7-Rudo method is actually applied, the ground 1 excavated by the 7-Rudo machine 2 has a well-compacted sand layer with a natural water pressure of 265 to an N value of 50 or more. It was a homogeneous fine sand with a particle size of 100 to 200 microns.

Initially, when construction was carried out using the conventional method of immediately backfilling the tail void 5 that occurs with excavation using the cutter 6 with a chemical solution, sand and the chemical solution accumulated between the shielding machine 2 and the tail packing 4. , it is compressed to form a sand camber with a wedge-shaped cross-section, which impairs the flexibility of the tail packing 4 and causes the tail packing 4 to be pressed against the segment 6 with excessive force, causing the tail packing 4 to
was damaged and the tail packing 4 had to be replaced after digging only 50m.

Therefore, by adopting the construction method of the present invention, highly concentrated mud water is immediately injected back into the tail void 5 after the shield machine 2 has passed, causing the collapse of the ground 1 and the introduction of fine sand into the sea head machine 2. To prevent intrusion, a chemical solution was injected from about 9 meters behind to solidify it, including the highly concentrated muddy water, and Segment 6 was fixed underground.

The formulation of the highly concentrated muddy water used here is shown in the table below.

The injection pressure of high concentration mud water is natural water pressure 2.65”9/ct
The pressure was set to 3.0 to 3.2 Ki1//7, which is higher than t, but if the pressure is set higher than this, the water stop property of the tail void /4 will deteriorate, and the shield machine 2. As highly concentrated muddy water enters the
I tried to maintain this injection pressure as much as possible.

As a result, the remaining excavation distance of 415m was covered by Tailpackin 4.
It was possible to excavate without causing any damage.

As described above, according to the backfilling method to which the backfilling method of the present invention is applied, it is possible to prevent the collapse of the ground and the intrusion of earth and sand into the shield machine, and also has the advantage of preventing damage to the tail packing. It is possible to improve the work efficiency.

[Brief explanation of the drawing]

The drawing is a schematic cross-sectional view of the N'rdoe method in one embodiment of the present invention. 2...7-first machine, 5...tail void, 6...
Segment, 7...-Next backfill injection, 8...Secondary backfill injection, 9...-Ground hole for next backfill injection, 12.
・Grout hose for secondary backfill injection.

Claims (1)

[Claims] /- When primary lining of a shield tunnel is performed using a shield machine, highly viscous and highly concentrated mud water is injected into the tail void created by the forward movement of the shield machine through grout holes provided in the segments, and then solidified. A backfill injection method in the /-root construction method, characterized in that the segments are fixed by backfilling material.