JP2683814B2 - Reinforcement method of soft ground around the front face of shield tunnel - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention relates to a construction method for reinforcing surrounding ground when a tunnel is constructed on soft ground.

<Prior Art> A muddy water shield machine is a device that holds muddy water on a face and presses the muddy water to prevent the natural ground from collapsing while excavating.

However, since the sand ground and gravel ground have good water flowability, the mud pressure of the mud shield becomes larger, pushing the mud into the ground and causing it to slip, or suddenly the mud jets to the surface of the earth. The phenomenon occurs.

If the mud is lost, the mud that pressurizes the face and balances the pressure of the earth and sand will disappear.

Therefore, the face may collapse in some cases.

The following construction methods have been adopted in order to avoid such problems, but each has its drawbacks.

<B> A method of strictly controlling the mud pressure.

<B> A method of improving and strengthening the ground by injecting a chemical solution or freezing.

<Problems to be Solved by the Present Invention> In the conventional methods such as the above-mentioned <a>, it is not clear what numerical value is the optimum mud pressure for the ground, and therefore management is difficult. .

Moreover, such a method cannot deal with a sudden change in the condition of the ground or the state of water discharge.

The method such as <b> above has a problem that the reliability of the construction method is low because the temporary construction cost other than the main construction cost increases significantly and the chemical reaction in the ground is expected. .

<Purpose of the present invention> The present invention has been made to solve the above-mentioned problems, and it is possible to construct a tunnel lining body surrounding a tunnel lining body that can be constructed at low cost and with high reliability by simple construction. The purpose is to provide a ground reinforcement method.

<Means for Solving Problems> That is, the present invention is applied to the surrounding ground such as a tunnel face,
It is a construction method in which a large number of rod-shaped bodies are press-fitted to reduce the gaps between soil particles, where water and air existed until then, and as a result improve the condition of the ground as a whole.

<Structure of the Present Invention> Next, examples of the present invention will be described.

<A> Opening on the side surface of the tunnel lining body A large number of holes are formed on the ceiling surface of the tunnel lining body 1.

However, in the case of the shield construction method, it is possible to preliminarily form the opening 3 in the segment 2 located on the ceiling side among the segments 2. (FIG. 4) In that case, the opening 3 is filled with a packing material to prevent the inflow of groundwater.

<B> Press-fitting of rod-shaped body The rod-shaped body 4 is press-fitted toward the ground through the large number of openings 3. (Figs. 2, 3) The rod-shaped body 4 is connected and extended in the middle to secure a predetermined length.

The press-fitting method is hitting, hydraulic pressure, or any other known method.

After the press-fitting, the opening 3 is filled with mortar to prevent the inflow of groundwater.

<C> Insertion direction The insertion direction of the rod-shaped body 4 is not directed directly above in the vertical direction, but at an angle inclined with respect to the traveling direction of the tunnel lining body 1. (FIG. 3) Further, in the cross section of the tunnel lining body 1, it is performed not on the center line but at an angle opened to both sides (FIG. 2).

However, if the purpose is to improve the ground directly under the tunnel lining, press fitting vertically upward is also significant.

<D> In the case of the shield construction method In the case of the shield construction method, the rod-shaped body 4 is press-fitted by penetrating the packing material of the opening 2 of the segment 2 and then reinforced with cement milk or the like to improve the water blocking effect.

<Operation of the Present Invention> When a large number of rod-shaped bodies 4 are inserted into the ground from above the tunnel lining body, the state shown in FIG. 1 is obtained.

Into the ground above the tunnel lining body 1, a large number of groups of rod-shaped bodies 4 which did not exist until then are driven in, and the soil corresponding to the volume thereof is compressed.

At that time, since there is a space between the soil particles, the gaps between the particles are crushed, and the water and air between the particles are discharged to be satisfactorily improved.

Therefore, the ground in front of the face of the tunnel 1 is compacted.

<Effects of the Present Invention> Since the present invention is as described above, the following effects can be expected.

<B> The ground above and in front of the tunnel face can be strengthened.

Therefore, even if there is a change in the muddy water pressure in the muddy water shield machine, it will not immediately affect the natural ground, so that delicate muddy water pressure management will not be necessary, the allowable range will be wide, and control will be easy.

<B> Once the shield machine has passed, it was difficult to prevent ground subsidence even if backfilling injection was performed.

However, according to this construction method, the ground can be sufficiently reinforced by selecting the number of rods, the length, the direction, etc., so that the settlement of the ground can be almost prevented.

<C> All the work can be performed from the inside of the pit that is being dug.

Therefore, it is not necessary to perform a temporary work such as separately injecting a chemical solution from the ground to reinforce the ground, which is economical and can shorten the construction period.

<D> Unlike the injection of a chemical solution whose location is unknown and the freezing method in which the improvement range is difficult to limit, the range of reinforcement and the range of increasing resistance are clear.

Therefore, it is possible to reinforce the natural ground without limiting the work to a necessary extent without performing unnecessary work.

<E> By implanting a large number of rod-shaped bodies that have not existed in the soft ground until then, the soil corresponding to the volume can be compacted to solidly reinforce and improve the soft ground.

<F> Since construction on existing underground structures can be performed just like new underground structures, it is quick and easy without excavating or backfilling the ground around existing underground structures. And it can be done safely.

[Brief description of the drawings]

 Fig. 1: Explanatory diagram after construction of the method of the present invention Fig. 2: Front view of construction state Fig. 3: Side view of construction state Fig. 4: Explanatory diagram of construction example using segments

Claims (1)

(57) [Claims] 1. A method for reinforcing soft ground around a front face of a shield tunnel, wherein a large number of rod-shaped bodies are press-fitted from inside the lining body of the shield tunnel toward the soft ground around the front face of the tunnel. This is a shield tunnel in which the soft ground in the press-fitted area of the rod is compacted by the volume equivalent to that of the rod to reduce the gaps between particles such as earth and sand to compactly compact it and increase its strength as a whole. Reinforcement method for soft ground around the front of the face.