JPH07991B2 - Shielding method using super absorbent resin - Google Patents

Description

TECHNICAL FIELD The present invention relates to a shield construction method using a highly water-absorbent resin.

<Prior Art> As is well known, there is a shield construction method as a construction method for a subway tunnel or the like, and various types are provided according to the properties of the ground to be excavated.

By the way, when excavating a sand layer or gravel layer ground that has been flooded by the shield construction method, there is a lot of water in the ground, so the face collapses and the flow of excavated sediment becomes poor, making it difficult to discharge the excavated soil. was there.

Therefore, for example, as disclosed in Japanese Patent Application Laid-Open No. 59-134296, there has been proposed a method of mixing a highly water-absorbent resin into the earth and sand of the cutting face or the earth and sand excavated.

According to the construction method disclosed in this publication, the superabsorbent resin mixed in the earth and sand absorbs water and gels,
Water-stopping property and fluidity are given to the earth and sand, which makes it possible to stabilize the cutting face and facilitate the discharge of excavated earth and sand.

However, such a construction method has a problem described below particularly in the treatment of excavated sediment.

<< Problems to be Solved by the Invention >> That is, the water-absorbent resin expands its volume several hundred times or more when it absorbs water, and once it absorbs water, it hardly releases in a natural state.

Therefore, excavated soil mixed with gelled super absorbent resin exhibits compressibility similar to sponge, has high fluidity, and its volume may increase significantly. As the amount increases and the cost increases,
There was also a problem with the disposal of waste.

The present invention has been made in view of the above problems, and its object is to facilitate the treatment of excavated soil mixed with a superabsorbent resin in a shield construction method using the superabsorbent resin. It is to provide a shield construction method using a super absorbent polymer that can be performed.

<Means for Solving Problems> In order to achieve the above object, the present invention provides a shield method using a highly water-absorbent resin, which is provided behind the cutter head when excavating a tunnel with a shield machine. By mixing a superabsorbent resin into the excavated earth and sand in the earth pressure chamber formed and gelling the same, the excavated earth and sand is provided with water stoppage and fluidity, and the gelled superabsorbent resin is mixed. At the time of discharging the excavated earth and sand from the earth pressure chamber, after the excavated earth and sand is discharged from the pressurized area of the shield machine by fluid transportation,
It is characterized in that an alkaline or acidic salt such as CaCl ₂ , NaCl or Ca (OH) _{2 is} mixed outside the earth pressure chamber.

Further, in the present invention, as the salt, it is preferable to mix twice the weight of the monovalent salt and the equivalent amount of the divalent salt with respect to the mixed dry weight of the super absorbent polymer.

Further, in the present invention, it is preferable that two kinds of salts, alkaline and acidic, are simultaneously mixed as the salt.

Here, after the excavated earth and sand is discharged from the pressurized area by fluid transportation, it means after the excavated earth and sand is released from the pressurized area, and fluid transportation is the soil of the shield machine. Refers to a transportation mode in which the excavated sand is fluidly transported while maintaining the pressurized state in the pressure chamber, other than when pressure-fed through a mud pipe or the like,
This also includes the case where excavated soil is transported by a screw conveyor.

<Operation> According to the method for treating excavated soil having the above-mentioned configuration, when gelled superabsorbent resin is mixed, the excavated soil in the earth pressure chamber is provided with water stopping ability, so that even if the ground has a lot of water Stability is maintained, and the excavated sediment in the soil pressure chamber is provided with fluidity so that the excavated sediment can be discharged by fluid transport via a screw conveyor or the like. After such excavated earth and sand is discharged by fluid transport, if alkaline or acidic salts such as CaCl ₂ , NaCl, Ca (OH) ₂ are mixed, the excavated earth and sand will release the water taken up by the super absorbent resin. , It is easily compacted by being degelled and compressed by the salting out phenomenon.

<Example> Hereinafter, a preferred example of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 shows an embodiment of a shield construction method using the superabsorbent resin according to the present invention. The present invention is applied to a shield construction method for constructing a tunnel by an earth pressure type shield machine. , 10 is the shield machine main body.

At the tip of the shield machine main body 10, a cutter head 12 for excavating the earth and sand of the face is rotatably installed.

A partition wall 14 is fixedly provided on the back side of the cutter head 12, and an earth pressure chamber 16 is filled with the earth and sand excavated by the cutter head 12.
Are separated.

Reference numeral 18 is a shield jack for advancing the shield machine main body 10 toward the segment 20 with reaction force, and 22 is a drive motor for rotationally driving the cutter head 12.

Further, 24 has one end open to the earth pressure chamber 16 and
It is a screw conveyor for discharging the excavated earth and sand taken in 16 to the outside while maintaining the pressurized state in the earth pressure chamber 16, and the earth pressure chamber 16 at the rear side due to the earth pressure of the cutting face. An opening / closing lid 26 is provided to take out the excavated sediment transported by fluid while being opposed by the excavated sediment of FIG.

Then, in this embodiment, when encountering a sand layer or gravel ground that has stagnant water as described above, the cutting face becomes unstable and it becomes difficult to excavate, so the super absorbent resin is applied to the earth pressure chamber 16 and the ground of the cutting face. A supply pipe 28 for supply is installed.

The supply pipe 28 is connected to two containers 32 and 34 in which an air ejector 30, a granular highly water-absorbent resin, and a dry powder or granular material such as dry sand are individually stored. Is supplied to the earth pressure chamber 16 and the like by air transportation in a mixed state.

In the shield machine configured as described above, the excavated earth and sand taken into the earth pressure chamber 16 via the cutter head 12 is mixed with a highly water-absorbent resin, and this resin absorbs moisture in the excavated earth and sand. Gelation, thereby imparting waterproofness and fluidity to the excavated earth and sand in the earth pressure chamber 16, and maintaining the pressurization state in the earth pressure chamber to maintain the stability of the cutting face, and to the outside from the screw conveyor 24. Is discharged.

Then, the excavated earth and sand A mixed with the gel of the super absorbent resin taken out from the screw conveyor 24 is a belt conveyor installed below the opening / closing lid 26 of the screw conveyor 24.
It is carried to the rear by 36 and is carried out to the outside of the mine at Zuritro 38, but when it is transferred to Zuritro 38, the liquid or powdery salt B is mixed.

As this salt, for example, an alkaline or acidic salt such as CaCl ₂ , NaCl, Ca (OH) ₂ is used.

In this case, as the addition amount of the salt B, twice as much weight is added as the monovalent salt of NaCl as compared with the dry weight of the superabsorbent resin mixed, and CaCl _{2 as the} divalent salt is added. With Ca (OH) ₂ , the gel is completely decomposed and water is released when the same weight as the super absorbent resin is added.

A more preferable method of using the salt B is to use an alkaline salt and an acidic salt at the same time so that the PH of the excavated sediment in the degelled state becomes neutral.

As an example of such a usage method, assuming that the superabsorbent resin is added to the excavated earth and sand A at a concentration of 0.2% (powder weight / water weight), acidic CaCl ₂ and alkaline Ca (OH) ₂ of (high water absorbent resin weight): (CaCl ₂ ):
In the case of (Ca (OH) ₂ ) = 1: 1: 0.004, when added, the superabsorbent resin which presents monovalent acrylic acid and gels becomes neutral when it is degelled.

By the way, when salt B is added to and mixed with the excavated earth and sand A mixed with the gelled superabsorbent resin as described above, the cross-linking structure of the gel contracts, and the moisture taken in the cross-linking structure is shortened. The so-called salting-out phenomenon occurs in the air.

As a result, water is released from the excavated soil A to the outside, and if it is sandy soil, slump value of about 10 to 20 cm is 1 to 2c.
It will be reduced to about m, and sponge-like soil will release water, enabling compact compaction.

In addition, in the above-described embodiment, the case where the excavated earth and sand A is transferred from the belt conveyor 36 to the Zuritro 38 as an example where the salt B is added and mixed with the excavated earth and sand A mixed with the gelled superabsorbent resin, The place where B is added is not limited to this.
It may be outside or inside the pit as long as it is released from the 24 pressurized areas.

Further, in the above-mentioned embodiment, the earth pressure type shield machine is used as an example of the shield construction method, but the construction method using a mud type or a mud type shield machine is also applicable.

<< Effects of the Invention >> As described in detail in the above examples, according to the shield construction method using the superabsorbent resin according to the present invention, the main pressure chamber for excavated earth and sand mixed with the gelated superabsorbent resin is used. At the time of discharge from, the excavated earth and sand is discharged from the pressurized area of the shield machine by fluid transport, and then an alkaline or acidic salt such as CaCl ₂ , NaCl, Ca (OH) ₂ is mixed, so that the gelled high When carrying out the excavated earth and sand to which the water stopping and fluidity required for the excavated earth and sand in the earth pressure chamber by the water absorbent resin is carried out from the earth pressure chamber, by compacting the excavated earth and sand, the handling of the excavated earth and sand, The excavated soil can be easily processed by facilitating transportation.

[Brief description of drawings]

FIG. 1 is an explanatory view of an implementation state of a shield construction method to which the method of the present invention is applied. 10 …… Shield excavator main body A …… Excavated earth and sand mixed with gelled super absorbent resin B …… Salt

Claims (3)

[Claims] 1. In a shield construction method using a superabsorbent resin, when excavating a tunnel with a shield machine, the superabsorbent resin is mixed with excavated earth and sand in an earth pressure chamber formed behind the cutter head. By imparting water-stopping property and fluidity to the excavated earth and sand by gelling it, the excavated earth and sand is discharged when the excavated earth and sand mixed with the gelled superabsorbent resin is discharged from the earth pressure chamber. After being discharged from the pressurized area of the shield machine by fluid transportation, CaCl ₂ , NaCl, Ca (OH) ₂ or the like is mixed with an alkaline or acidic salt outside the earth pressure chamber, which is characterized by high water absorption. Shielding method using resin. 2. The salt is mixed with a monovalent salt in an amount twice as much as the mixed dry weight of the superabsorbent resin, and an equivalent amount of the divalent salt. A shield construction method using the highly water-absorbent resin according to claim 1. 3. A shield construction method using a superabsorbent resin according to claim 1 or 2, wherein the salt is a mixture of two kinds, alkaline and acidic, at the same time.