JP3994076B2 - Bubble generation method and bubble material used for bubble shield method in bubble shield method - Google Patents

Description

  The present invention relates to a bubble generation method and a bubble material suitable for use in a gravel ground with high water permeability in the bubble shield method.

Mud pressure system shield pressurized mud material used in, (a) Bentonite, (b) cellulosic, (c) polyacrylamide, (d) water-absorbent resin, (e) classified in the surfactant system Is done.

In general, the foam material used in the bubble shield method belongs to (e) surfactant-based mud material among these , and special foaming material (OK-2 ... cellulose-based polymer made from pulp as a raw material) Is produced by mixing air into an aqueous solution of a foaming material. By injecting this foam material into the face, the fluidity and water-stopping performance of the excavated soil can be improved, and adhesion of soil in the chamber can be prevented, and smooth excavation can be performed while ensuring the stability of the face. .

In the bubble shield method, the type of foaming material and foam material is determined from the properties of the excavated ground, that is, the particle size accumulation curve (see Non-Patent Document 1) . For example, as shown in FIG. 1, type A foaming material and foam material (solution viscosity: 2.7 mPa · s) are suitable for zone I or zone II made of clay, silt, fine sand, etc. B type foaming material and foam material (solution viscosity: 300 mPa · s) are suitable for zones II to III made of coarse sand. The B-type foam material is obtained by foaming a B-type foaming material. Specifically, the thickener OK-2 is added to OK-1 to impart viscosity to the bubbles, and the cell strength. Is an increase.

Bubble shield method technical data "Selection criteria for soil and special foam materials" March 2003 Shield Method Method Association http://www.shield-method.gr.jp/what/kiho.PDF

However, especially in the gravel ground with high water permeability, especially in the soil having a high water permeability coefficient belonging to the IV zone, even if the B type foam material is used, the bubbles are likely to disappear due to the abundance of groundwater. For this reason, it is difficult to stably hold the face, and problems such as eruption from the screw conveyor occur, which may hinder excavation.

Therefore, increasing the viscosity of the foaming material over the conventional B type viscosity so that the bubbles are difficult to defoam, the pressure in the foaming device is increased due to the viscosity, clogging, etc., the foaming ratio decreases, It becomes impossible to foam 6 times, which is the standard for B type foam materials . Therefore, in the case of carrying out the bubble shield method using a B-type foam material on gravel ground with high water permeability, conventionally, the use of other additive materials or an auxiliary method has been required.

The present invention solves the above problems, and it is possible to carry out the bubble shield method in the bubble shield method so that the air shield method can be carried out without using other additives and auxiliary methods even in highly permeable gravel ground. The present invention provides a foam material used in a production method and a bubble shield construction method.

In order to solve the above problems, the present invention uses a foaming material of B type and be further thickened while securing a predetermined expansion ratio, thereby gelled B type (hereinafter "gelling B We were able to obtain a cellular material of type ")."
That is, in the method for generating bubbles in the bubble shield method of the present invention, one or a mixture selected from CMC , guar gum and alginic acid is added as a thickener to a foaming material as a main agent, and a viscosity of 300 A foaming material solution adjusted to ˜500 mPa · s is foamed at a predetermined foaming ratio by a foaming apparatus , and an aqueous solution of metal ions is added to and mixed with the bubbles obtained immediately thereafter.
Moreover, this invention is characterized by adding guar gum in Claim 1 as said thickener.
The present invention is also characterized in that, in claim 1 or 2, the metal ion is a trivalent metal ion or a calcium ion.
In addition, the present invention is characterized in that in any one of claims 1 to 3 , a liquidity adjusting aid is added to the aqueous solution of metal ions.

Furthermore, the foam material used in the foam shield method of the present invention is a foam material as a main agent, and one or a mixture selected from CMC , guar gum, and alginic acid is added as a thickener to a viscosity of 300 The foaming material solution adjusted to ˜500 mPa · s is foamed at a predetermined foaming ratio by a foaming apparatus, and an aqueous solution of metal ions is added to the bubbles obtained immediately thereafter.

  By adding the metal ion solution, the main components of the bubbles discharged through the foaming apparatus are gelled and discharged from the excavator tip in a further thickened state while being maintained at the desired expansion ratio. The metal ion used is preferably a trivalent metal ion or calcium ion. By adding a liquid property adjusting aid, the liquid property is easily increased.

  FIG. 2 shows a bubble shield method to which the method of the present invention is applied. In the figure, 1 is a shield excavator and 2 is a tunnel segment constructed following the excavator 1.

  The shield excavator 1 includes a cutter disk 4 on the front surface of a cylindrical skin plate 3, and excavates the face by rotating the cutter disk 4 while moving forward while taking a reaction force at the front end of the segment 2 with a jack (not shown). The excavation gap taken into the chamber 6 on the back surface of the cutter disk 4 and partitioned by the partition wall 5 is transported by the screw conveyor 7 and delivered to the gap transport carriage disposed at the rear thereof for discharging. ing.

  In the rear part of the excavator 1, a transport rail 8 is installed in a tunnel mine surrounded by the segment 2, and in this embodiment, various carts constituting the bubble generation plant are connected in a row on the rail 8. ing. Each cart is composed of a foaming material storage cart 9, a driving cart 10, a control cart 11, and a foaming cart 12 in that order from the rear side. In addition, a metal ion storage tank 13 is disposed on the foaming cart 12. Has been.

  The storage cart 9 receives supply of foaming material from the foaming material pipe 14 drawn into the mine, and temporarily stores it here. The driving carriage 10 includes a foaming material injection pump 15 and an air compressor 16, the control carriage 11 includes a pump 15 and a controller 17 for the compressor 16, and the foaming carriage 12 includes a foaming device 18, each of which generates foam. It is connected via a material supply line and an air line.

  By the plant driving, the foaming material stored in the storage cart 9 is sent to the foaming device 18 by the pump 15, and the compressed air generated by the air compressor 16 inside the foaming device 18 is mixed at a predetermined pressure ratio, Foaming is performed at a predetermined foaming ratio and is discharged to the front surface of the cutter disk 4 through the bubble injection tube 19.

  In addition, the bubble injection pipe 19 is connected to the metal ion storage tank 13 through the supply pipe 20 and the pump P in the vicinity of the discharge end of the foaming device 18, and the metal ion solution is bubbled in the foaming device 18. It is mixed. This mixing ratio becomes a predetermined ratio by driving and controlling the pump P by the control device 17.

  In the above, the foaming material used is a B-type foaming material suitable for the aforementioned II to III zones, and the main component is the thickener in addition to the above-mentioned OK-1 which is the main component of the foaming material. As a foaming material solution, the viscosity is adjusted to 300 to 500 mPa · s by adding one or a mixture selected from CMC, guar gum and alginic acid.

The added C M C , guar gum, alginic acid or a mixture thereof gels in the presence of trivalent metal ions or calcium ions, and thickens, for example, 2 to 40 times.

In the present invention, a B-type foaming material solution is foamed by a foaming device 18 at a predetermined foaming ratio, and an aqueous metal ion solution is added to and mixed with bubbles obtained immediately thereafter to increase the viscosity. The gelled B type foam material thus obtained is supplied to the front surface of the cutter disk 4 . Therefore , according to the present invention, even excavation can be performed without using other additives and auxiliary methods even in the case of sandy gravel ground with high water permeability, that is, soil having a high water permeability coefficient belonging to the IV zone. Moreover, according to this invention, since the plastic fluidity | liquidity and water-stopping property of the earth and sand in a chamber improve, the ejection from the screw conveyor 7 can also be prevented.

Examples of the metal ions include aluminum compounds such as alum and sulfate bands, solutions of trivalent metal ions such as iron sulfate, iron chloride, sodium aluminate, borax, and boric acid, and calcium chloride solutions. Can be mentioned.

In addition to the above, liquidity adjusting aids such as an aqueous sodium hydroxide solution and an aqueous sulfuric acid solution are also mixed in advance in the metal ion solution. This is because the degree of thickening differs depending on the liquidity. For example, in the case of guar gum, the degree of thickening increases on the alkali side, and in the case of CMC, the degree of thickening increases on the acidic side.

These aqueous solutions of metal ions are desirably mixed at a mixing ratio of about 5 to 10% by volume with respect to the stock solution of the foaming material solution in the form of 0.5 to 10% aqueous solution. This is because when the mixing amount is less than 5%, the target viscosity increase due to gelation is not remarkable, and when it exceeds 10%, volume shrinkage such as water separation due to coagulation occurs. This is because a problem arises in that a simple bubble cannot be formed.

When the ground to be excavated changes from the IV zone to the III zone or the II zone, the pump P is stopped and the gelation operation is stopped. Thereby, it becomes possible to supply a foam material to a face with the same viscosity and foaming ratio, and the pump load etc. accompanying a thickening can also be reduced. Further, since the type of the bubble material can be easily changed from the gelled B type to the B type according to the ground properties by simply switching the pump P, it is not necessary to interrupt the excavation work.

<< Example 1 >>
In this example, three types of foam materials having different viscosities of A type, B type, and gelled B type were injected into the washing sand, and the slump value and the injection rate were compared as shown in Tables 1 to 3 below. did. All slump values were measured with a C-type viscometer.

From each table, it is understood that the height of the bubble viscosity is proportional to the magnitude of the slump value. This suggests that when the bubble strength increases due to an increase in viscosity, it becomes difficult to break or defoam. In addition, the gelled B type cell material shown in Table 3 has a significantly increased cell strength and is less likely to be broken or defoamed compared to the A type material shown in Table 1 and the B type cell material shown in Table 2. ing. Therefore, according to the gelled B type foam material of the present invention, it is possible to carry out the bubble shield construction method without using other additive materials and auxiliary construction methods even on highly permeable sand gravel ground.

この表からは、塩化鉄イオンの介在により増粘し、また同一添加容量であっても、液性がアルカリ側になるほど増粘度合いが高いことが確認された。 << Example 2 >>
A 0.6% solution of guar gum, which is a thickener component, is gelled using iron chloride ions, a caustic soda solution is used as a liquidity adjusting agent, and a change in viscosity due to liquidity is observed. Results were obtained. The viscosity in the solution state was measured with a viscose tester.

From this table, it was confirmed that the viscosity increased due to the intervention of iron chloride ions, and the viscosity increased as the liquid property became alkaline, even with the same added capacity.

この表からは、液性が酸性側であると増粘効果がなく（ｐＨ４．５の場合には粘度５００ｍＰａ・ｓのまま）、また過度にアルカリ側に偏ってもかえって粘度が低下し（ｐＨ１０．１の場合には、粘度１４５０ｍＰａ・ｓ）、ｐＨ９．５の場合に最大の増粘効果（粘度１８００ｍＰａ・ｓ）を得ることが判明した。なお、アルミン酸ソーダはそれ自体がアルカリ性物質であるため、希硫酸の添加量に応じてその液性が変化する。 << Example 3 >>
A 0.6% solution of guar gum, which is a thickener component, was gelled using sodium aluminate, and a change in viscosity due to liquidity was observed using a dilute sulfuric acid solution as a liquidity adjusting agent. The results shown are obtained. The viscosity in the solution state was measured with a viscose tester.

From this table, it is found that there is no thickening effect when the liquid is on the acidic side (in the case of pH 4.5, the viscosity is 500 mPa · s) , and even if it is excessively biased toward the alkali side, the viscosity is lowered (pH 10). In the case of 0.1, it was found that the maximum thickening effect (viscosity 1800 mPa · s) was obtained in the case of pH 9.5 . Since sodium aluminate itself is an alkaline substance, its liquidity changes depending on the amount of dilute sulfuric acid added.

この表からは、金属イオン（ホウ砂）の増加に応じて粘性が増すこと及びｐＨ８．５の場合に最大の増粘効果（粘度２００００ｍＰａ・ｓ）を得ることが判明した。また、本実施例の場合には、液性調整用助剤を用いることなく、ゲル化Ｂタイプの気泡材が得られることが判明した。 << Example 4 >>
A 0.6% solution of guar gum, which is a thickener component, was gelled using borax and the change in viscosity due to the liquid property was observed. The results shown in Table 6 below were obtained. The viscosity in the solution state was measured with a viscose tester.

From this table, it was found that the viscosity increases as the metal ions (borax) increase, and that the maximum thickening effect (viscosity 20000 mPa · s) is obtained at pH 8.5 . Moreover, in the case of the present Example, it turned out that a gel-type B type foam material is obtained, without using the liquidity adjustment adjuvant.

The present invention is suitable for excavation of gravel ground with high water permeability in the bubble shield method.
According to the present invention, by adding an aqueous solution of metal ions to the bubbles discharged through the foaming apparatus, the main component of the bubbles is gelled, and the tip of the excavator is further thickened while being maintained at a predetermined foaming ratio. More discharged. The discharged gelled B type bubble material has a significantly increased bubble strength as compared with the conventional B type bubble material, and is therefore difficult to be defoamed. Therefore, according to the present invention, it is possible to carry out the bubble shield construction method without using other additives and auxiliary construction methods even on gravel ground with high water permeability. The aqueous solution of metal ions is preferably an aqueous solution containing trivalent metal ions or calcium ions. By adding a liquidity adjusting aid to the aqueous solution of metal ions, the formation of gelled bubbles can be further promoted.

It is a graph which shows the selection criteria of soil quality and foaming material. It is sectional drawing for description which shows the bubble shield construction method to which this invention method is applied.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Shield excavator 2 Segment 9, 10, 11, 12 Bubble production plant (9 Foaming material storage cart, 10 drive cart, 11 control cart, 12 foaming cart)
13 Metal ion storage tank 18 Foaming device

Claims (5)

A foaming device prepared by adding one or a mixture selected from CMC , guar gum and alginic acid as a thickener to a foaming material as a main agent and adjusting the viscosity to 300 to 500 mPa · s. A method of generating bubbles in the bubble shield method, wherein foaming is performed at a predetermined foaming ratio, and an aqueous solution of metal ions is added and mixed immediately after the bubbles are obtained. The method for generating bubbles in the bubble shield method according to claim 1, wherein guar gum is added as the thickener . 3. The method for generating bubbles in the bubble shield method according to claim 1, wherein the metal ions are trivalent metal ions or calcium ions. The method for generating bubbles in the bubble shield method according to any one of claims 1 to 3, wherein an auxiliary for adjusting liquidity is added to the aqueous solution of metal ions. A foaming device prepared by adding one or a mixture selected from CMC , guar gum and alginic acid as a thickener to a foaming material as a main agent and adjusting the viscosity to 300 to 500 mPa · s. A foam material used in a foam shield method, wherein foaming is performed at a predetermined foaming ratio, and an aqueous solution of metal ions is added and mixed immediately after the foam is obtained .

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