JP3905348B2 - Face stabilization method in shield method, and mud for holding face - Google Patents

Description

【００２６】
その結果、図３に示すように、前記切羽保持用泥水４が浸透した浸透領域１について、切羽保持用泥水４による泥水圧を除荷させて、地盤２を安定状態から崩壊させた場合の崩壊時の泥水圧力を測定すると、地盤２の間隙水圧と等しい時点であることがわかる。
【００２７】
これらは、切羽３における泥土圧の下限値は、一般に主働土圧＋地盤の間隙水圧、つまり地盤２が切羽３に及ぼす圧力と地盤の間隙を満たす間隙水の水圧との総和、とされているが、この実験結果より上記切羽保持用泥水４を地盤２に浸透させて前記浸透領域１を形成することにより、主働土圧が０、つまり地盤２が切羽３に及ぼす圧力の影響がない程度に切羽３近傍の地盤２が改良されたこととなる。
【００２８】
【発明の効果】
請求項１および２に記載のシールド工法における切羽安定方法によれば、シールド工法において切羽の安定状態を継続させるシールド工法の切羽安定工法であって、掘削した地盤に含まれる細粒分や粘土と水の他にはベントナイトと該ベントナイトの粒子を凝集させるアクリルアミド系高分子凝集剤のみが配合されることにより、地盤への浸透性を有し、かつ地盤改良効果を有する切羽保持用泥水を切羽から地盤に浸透させて、該切羽保持用泥水が浸透した地盤の浸透領域全体に自立性を持たせることから、切羽保持用泥水の泥水圧と、浸透領域自らの自立性により、シールド掘進においても切羽が崩壊することなく保持され、常に安定した掘削を得ることが可能となった。
また、前記切羽と前記泥水式シールドマシンの隔壁との間に満たされた切羽保持用泥水が、地盤に逃げる逸泥現象を低減することができた。
さらに、前記切羽の崩壊による土砂の巻き込みが減少するため、泥水式シールドマシンを構成し、掘削した土砂を切羽保持用泥水と混合するアジテータが過負荷で停止する現象を低減することが可能となった。
【００２９】
請求項３および４に記載のシールド工法における切羽保持用泥水によれば、掘削した地盤に含まれる細粒分や粘土と、水と、ベントナイトと、アクリルアミド系高分子凝集剤のみとを配合させることから、切羽から地盤の浸透領域には自立性を有する改良地盤体を形成することが可能となった。
【００３０】
請求項５に記載のシールド工法における切羽保持用泥水によれば、前記切羽保持用泥水を構成するアクリルアミド系高分子凝集剤は、分子量が１００万以上、イオン化度が０〜１００モル％であるアクリル系高分子からなる分散粒子径が１００μｍ以下の油中水型エマルジョンの形態を有する高分子凝集剤であって、用いるアクリル系高分子として、ノニオン性としては、ポリアクリルアミド、アニオン性としては、アクリル酸、メタアクリル酸、イタコン酸、マレイン酸、アクリルアミド２−メチルプロパンスルフォン酸、ビニルスルフォン酸、スチレンスルフォン酸、などの単独重合体あるいはアクリルアミドとの共重合体、カチオン性としては、アクリル酸ジメチルアミノエチル、メタクリル酸ジメチルアミノプロピルメタアクリルアミド、アクリロイルエキシエチルトリメチルアンモニウムクロリド、メタアクリロイルオキシエチルトリメチルアンモニウムクロイド、アクリロイルアミノプロピルトリメチルアンモニウムクロリド、メタアクリロイルアミノプロピルトリメチルアンモニウムクロリド、アクリロイル２−ヒドロキシプロピルリド、などの単独重合体あるいはアクリルアミドとの共重合体のいずれかを用いることから、切羽保持用泥水は泥水工法として泥水としての機能を果たしながら、自立性を有する改良地盤体を形成することが可能となった。
【図面の簡単な説明】
【図１】 本発明に係るシールド工法における切羽安定方法の概念図を示す図である。
【図２】 本発明に係るシールド工法における切羽安定方法を用いた切羽部の詳細を示す図である。
【図３】 本発明に係るシールド工法における切羽安定方法を用いた切羽部の泥水圧力の状況を示す図である。
【図４】 本発明に係るシールド工法における切羽安定方法に用いられる泥水式シールドマシンの概略を示す図である。
【図５】 従来のシールド工法における切羽部の詳細を示す図である。
【符号の説明】
１ 浸透領域
２ 地盤
３ 切羽
４ 切羽保持用泥水
５ 排泥管
６ ベントナイト
７ アクリルアミド系高分子凝集剤
８ トンネル
９ 泥水式シールドマシン
１０ 隔壁
１１ 送泥管
１２ アジテータ
２１ 泥膜
２２ 地盤
２３ 切羽
２４ 泥水[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for stabilizing a face in a shield method that can hold a face well and perform stable excavation work, and a mud for holding face.
[0002]
[Prior art]
In the shield method, it is important to stabilize the face and excavate for safe construction and to suppress the influence on the ground around the tunnel. However, sand ground with a uniform particle size and unconsolidated gravel ground are not self-supporting, so the face is likely to collapse, and there are many problems affecting construction and surroundings.
[0003]
In the muddy water type shield which is the mainstream of the shield construction method, as shown in FIG. 5, the muddy water 24 used for excavation forms a mud film 21 on the surface of the face 23 as in the case of the continuous underground wall, Thus, the ground 22 is stabilized by transmitting the muddy water pressure to the ground 22.
[0004]
[Problems to be solved by the invention]
However, in the shield method, since the cutter of the shield machine always cuts the surface of the ground 22, the mud film 21 formed on the surface of the face 23 cannot be held, and the sand ground or hard solid with a uniform particle size cannot be retained. In soil conditions such as ungraved gravel ground, the face 23 was liable to collapse.
[0005]
In view of the above circumstances, an object of the present invention is to provide a face stabilization method in a shield method that can hold a face well and perform stable excavation work, and a face holding mud.
[0006]
[Means for Solving the Problems]
The face stabilization method in the shield method according to claim 1 is a face stabilization method in the shield method that continues the stable state of the face, and includes fine particles and clay contained in the excavated ground, water, bentonite, It contains only the acrylamide polymer flocculant for agglomerating the bentonite particles, and pressurizes and supplies the face holding muddy water having permeability to the ground to infiltrate the face from the face. It is characterized in that the entire infiltration area of the ground infiltrated with muddy water is improved to cause the entire infiltration ground to solidify and have independence.
The face stabilization method in the shield method according to claim 2 is the face stabilization method in the shield method according to claim 1, wherein the acrylamide polymer flocculant has a form of a water-in-oil emulsion. Yes.
[0007]
The face retaining mud in the shield construction method according to claim 3 is the face retaining mud in the shield construction method used in the face stabilization method in the shield construction method according to claim 1, wherein fine particles contained in the excavated ground Only clay, water, bentonite, and an acrylamide polymer flocculant that agglomerates the bentonite particles are blended, and are characterized by having permeability to the ground.
The face retaining mud in the shield method according to claim 4 is the face retaining mud in the shield method according to claim 3, wherein the acrylamide polymer flocculant has the form of a water-in-oil emulsion. Yes.
[0008]
That is, in the present invention, in order to agglomerate bentonite and its bentonite particles in addition to fine particles and clay and water contained in the excavated ground as muddy water used for holding the face in the muddy water shield method. The main point is to use muddy water containing only the acrylamide polymer flocculant of the above, and the bentonite particles in the muddy water are naturally only supplied by supplying the muddy water for holding the face to the face at a predetermined muddy water pressure. Agglomerates to a certain large particle size and penetrates into the ground in front of the face, thereby solidifying the ground in the infiltrated area and improving the ground so that it can be excavated, thereby making the face independent It is possible to dampen. In addition, since the infiltration region (that is, the ground improvement region) of the face retaining mud gradually advances along with the excavation, the excavation can be performed while the face is always stably standing independently.
Therefore, according to the present invention, stable excavation work can be performed while keeping the face always good and preventing its collapsing as compared with the case of the conventional general mud shield method in which the mud film is merely formed on the face. Is possible.
In addition, the muddy water for holding a face according to the present invention is able to obtain a ground improvement effect to the extent that it naturally penetrates into the ground in front of the face as described above, and the solidification phenomenon occurs there and the face becomes independent. For that purpose, in addition to fine particles contained in the excavated ground, clay and water, it is sufficient to use muddy water containing only bentonite and acrylamide polymer flocculant. There are no particular limitations on the specific composition of the ingredients, their composition, the properties of the muddy water (specific gravity, viscosity, etc.), the muddy water pressure to be retained in the face, etc. What is necessary is just to set suitably in consideration of various conditions.
If the specific example of the mud for holding face of this invention is given, the acrylamide polymer flocculent which comprises the mud for holding face , for example like the mud for holding face in the shield construction method according to claim 5 has a molecular weight. Is a polymer flocculant having the form of a water- in- oil emulsion having a dispersed particle size of 100 μm or less, which is made of an acrylic polymer having an ionization degree of 0 to 100 mol%. As a molecule, polyacrylamide is used as nonionic, and homopolymers such as acrylic acid, methacrylic acid, itaconic acid, maleic acid, acrylamide 2-methylpropane sulfonic acid, vinyl sulfonic acid, and styrene sulfonic acid are used as anionic. Or a copolymer with acrylamide, and as cationic, dimethyl acrylate Noethyl, dimethylaminopropyl methacrylate, acryloyl exciethyltrimethylammonium chloride, methacryloyloxyethyltrimethylammonium chloride, acryloylaminopropyltrimethylammonium chloride, methacryloylaminopropyltrimethylammonium chloride, acryloyl 2-hydroxypropylide, etc. It is conceivable to use either a polymer or a copolymer with acrylamide.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the face stabilization method and the face holding mud in the shield method according to the present invention will be described with reference to FIGS. 1 to 4.
[0010]
The tunnel 8 is constructed by a construction method using a muddy water type shield machine 9 as shown in FIG. In general, the muddy water type shield method using the muddy water type shield machine 9 is a method in which the muffled water 4 for holding the face pressed between the face 3 and the partition wall 10 of the muddy water type shield machine 9 is pressed through a mud pipe 11. In addition to satisfying and stabilizing the face 3, the excavated earth and sand are taken into the face retaining mud 4 and fluidly transported through the mud pipe 5 as waste water.
In this embodiment, in the construction of a tunnel 8 in gravel, in addition to the fine grain fraction and clay and mud contained in the excavated soil, bentonite 6, only acrylamide polymer flocculant 7 is blended the The face retaining mud 4 is used.
[0011]
In the face retaining mud 4, waste mud containing the excavated earth and sand transported through the mud pipe 5 is sent to a mud treatment plant (not shown), and the earth and sand contained in the waste mud is classified. Thus, the mud is adjusted to a predetermined property, pressurized again by the mud pipe 11 and fluid transported between the face 3 and the partition wall 10. That is, the face retaining mud 4 is not made into mud using a new material, but utilizes fine particles contained in the ground 2 being excavated.
[0012]
The bentonite 6 blended in the face retaining mud 4 is a kind of clay mineral mainly composed of montmorillonite. When mixed with water, the bentonite 6 increases in viscosity and specific gravity, and increases in amount to become a gel. Conventionally, it is used as a bentonite stabilization liquid in the muddy water method when excavating a well or a continuous underground wall.
[0013]
Similarly, the acrylamide-based polymer flocculant 7 blended in the face retaining mud 4 contains acid amide groups rich in reactivity in the polymer, and can easily produce various derivatives. It has characteristics. Further, it is a water-soluble functional polymer that can be copolymerized with various monomers (hydrophilic to hydrophobic) and can control the structure, and can meet a wide range of needs. Conventionally, it is used for the coagulation sedimentation of suspended wastewater, gravel, crushed stone, stone washing civil engineering muddy water treatment, weak acidity to neutral wastewater treatment, and the like.
[0014]
In the present embodiment, the acrylamide polymer flocculant 7 is a water- in- oil emulsion having a dispersed particle diameter of 100 μm or less made of an acrylic polymer having a molecular weight of 1 million or more and an ionization degree of 0 to 100 mol% . A polymer flocculant having a form , wherein the acrylic polymer is non-ionic polyacrylamide, and anionic is acrylic acid, methacrylic acid, itaconic acid, maleic acid, acrylamide 2-methylpropane sulfonic acid, vinyl sulfone Homopolymers such as acid, styrene sulfonic acid, etc. or copolymers with acrylamide, and cationic properties include dimethylaminoethyl acrylate, dimethylaminopropyl methacrylate, acryloyl exciethyltrimethylammonium chloride, methacryloyloxy Trimethylammonium click Lloyd, acryloyl aminopropyl trimethylammonium chloride, methacryloyloxy aminopropyl trimethylammonium chloride, it may be used any of a copolymer of homopolymer or acrylamide acryloyl 2-hydroxypropyl chloride, and the like.
Most preferred is a nonionic, anionic or chaotic water-soluble polymer having an ionization degree of 0 to 30 mol%.
[0015]
The properties of the mud water 4 for retaining the face made of such a material is that mud is produced with a specific gravity of 1 to 1.5 and a funnel coefficient of 60 seconds or less. In view of the fact that the properties of the muddy water conventionally used in the muddy water type shield method are generally about 1.15 to 1.25 and the funnel viscosity is about 25 to 30 s, the properties of the muddy water 4 for holding the face used in the present embodiment are: It can be said that it is almost the same as the conventional muddy water.
[0016]
Funnel viscosity is an index that is generally used as a guideline for maintaining the quality of muddy water. By measuring the time for a certain amount of muddy water to flow, the degree of viscosity is evaluated. Is.
[0017]
The face retaining mud 4 containing such a material penetrates between the particles in the ground 2 without forming a mud film on the face 3, but as shown in FIG. Is limited, and there is no such phenomenon that the mud water 4 for retaining the face escapes into the ground 2. The permeation region 1 is determined by the permeation resistance generated when the face retaining mud 4 penetrates between the particles in the ground 2 and the mud pressure of the face retaining mud 4. Osmosis ends when the water pressure balance is maintained.
[0018]
That is, as shown in FIG. 1, even when the face 3 is being excavated, the face holding mud 4 has the same length as the distance excavated in order to always maintain the balance between the permeation resistance and the mud pressure. Now, the penetration of the face retaining mud 4 into the ground will proceed. Therefore, even if the face 3 is continuously excavated, the permeation region 1 always maintains a state having a permeation width L.
[0019]
Moreover, the said infiltration area | region 1 shows the solidification phenomenon by mix | blending only the said bentonite 6 and the said acrylamide type polymer flocculant 7 in muddy water, and forms the improved ground body which has self-supporting property. In addition, the blending amount of the acrylamide polymer flocculant 7 in the face retaining mud 4 is 0.05% or less in terms of volume ratio, and if the amount exceeding this is blended, the face retaining mud 4 is the mud construction method. Can not fulfill the function of muddy water.
[0020]
Note that the present embodiment shown here is merely an example, and it goes without saying that any form can be adopted without being limited to the present embodiment unless departing from the gist of the present invention.
[0021]
According to the configuration described above, as shown in FIG. 2, since there is an infiltration region 1 having an infiltration width L in the vicinity including the face 3, the mud pressure of the face retaining mud 4 and the infiltration region 1 own Due to the independence, the face 3 was maintained without collapsing even during shield digging, and it became possible to always obtain stable excavation.
[0022]
Along with this, the pressurized mud retaining pressure 4 filled through the mud pipe 11 between the face 3 and the partition wall 10 of the muddy water shield machine 9 reduces the phenomenon of mud escape to the ground 2. We were able to.
[0023]
Moreover, since the entrainment of the earth and sand due to the collapse of the face 3 is reduced, the phenomenon that the agitator 12 that configures the muddy water type shield machine 9 and mixes the excavated earth and sand with the face holding mud 4 is stopped due to overload is reduced. Became possible.
[0024]
In order to clarify the effect of the face retaining mud 4, a gravel ground having a gravel ratio of about 60% is formed in a simulated manner, the same stress state as the actual face is reproduced, and the face retaining mud 4 is infiltrated. The experiment was conducted. Table 1 shows the composition of the mud water 4 for retaining the face. In addition, only the bentonite 6 and the acrylamide polymer flocculant 7 are used for the face retaining mud 4 in addition to clay and water corresponding to fine particles contained in the excavated ground . The properties of the face retaining mud 4 are a specific gravity of 1.11 and a funnel viscosity of 30 s.
[0025]
[Table 1]

[0026]
As a result, as shown in FIG. 3 , with respect to the infiltration region 1 into which the face retaining mud 4 has permeated, the mud pressure caused by the face retaining mud 4 is unloaded and the ground 2 collapses from a stable state. When the muddy water pressure at the time is measured, it is understood that the time is equal to the pore water pressure of the ground 2.
[0027]
The lower limit value of the mud pressure at the face 3 is generally the main earth pressure + the pore water pressure of the ground, that is, the sum of the pressure exerted on the face 3 by the ground 2 and the water pressure of the pore water filling the gap of the ground. However, from this experimental result, the work holding pressure 4 is infiltrated into the ground 2 to form the infiltration region 1, so that the main earth pressure is 0, that is, there is no influence of the pressure exerted on the face 3 by the ground 2. The ground 2 near the face 3 is improved.
[0028]
【The invention's effect】
According to the face stabilization method in the shield method according to claim 1 and 2, the face stabilization method of the shield method in which the stable state of the face is continued in the shield method, and the fine particles and clay contained in the excavated ground In addition to water, only the bentonite and the acrylamide polymer flocculant that agglomerates the bentonite particles are blended, so that the face retaining mud water having the ground improvement effect and the ground improvement effect can be obtained from the face. Since the entire infiltration area of the ground into which the face retaining mud has penetrated is infiltrated into the ground, the mud water pressure of the face retaining mud and the independence of the infiltration area itself can also be used in shield excavation. Is maintained without collapsing, making it possible to always obtain a stable excavation.
Further, the mud phenomenon for retaining the face filled between the face and the partition wall of the muddy water type shield machine could reduce the phenomenon of mud escape to the ground.
Furthermore, since the entrapment of earth and sand due to the collapse of the face is reduced, it is possible to reduce the phenomenon that an agitator that constitutes a mud type shield machine and mixes the excavated earth and sand with the face holding mud stops due to overload. It was.
[0029]
According to the mud for the working face holding the shield method according to claim 3 and 4, a fine fraction and clay contained in the excavated soil, water, bentonite and, thereby compounding the only acrylamide polymer flocculant Therefore, it became possible to form an improved ground body having independence in the infiltration region from the face to the ground.
[0030]
According to the face retaining mud in the shield method according to claim 5, the acrylamide polymer flocculant constituting the face retaining mud is an acrylic having a molecular weight of 1 million or more and an ionization degree of 0 to 100 mol%. A polymer flocculant having a dispersed particle size of 100 μm or less made of a polymer and having a form of a water- in- oil emulsion. The acrylic polymer used is non-ionic polyacrylamide, and anionic is acrylic. Homopolymers such as acid, methacrylic acid, itaconic acid, maleic acid, acrylamide 2-methylpropane sulfonic acid, vinyl sulfonic acid, styrene sulfonic acid, etc., or copolymers with acrylamide, and as cationic property, dimethylamino acrylate Ethyl, dimethylaminopropyl methacrylate methacrylate , Acryloyl exciethyltrimethylammonium chloride, methacryloyloxyethyltrimethylammonium chloride, acryloylaminopropyltrimethylammonium chloride, methacryloylaminopropyltrimethylammonium chloride, acryloyl 2-hydroxypropylide, and other homopolymers or copolymerized with acrylamide Since any one of the coalescence is used, it becomes possible to form an improved ground body having a self-supporting property while the mud water for retaining the face functions as a muddy water as a mud construction method.
[Brief description of the drawings]
FIG. 1 is a diagram showing a conceptual diagram of a face stabilization method in a shield method according to the present invention.
FIG. 2 is a diagram showing details of a face portion using a face stabilization method in the shield method according to the present invention.
FIG. 3 is a diagram showing the state of muddy water pressure in the face portion using the face stabilization method in the shield method according to the present invention.
FIG. 4 is a diagram showing an outline of a muddy water type shield machine used in a face stabilization method in the shield method according to the present invention.
FIG. 5 is a diagram showing details of a face part in a conventional shield method.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Infiltration area 2 Ground 3 Face 4 Face holding mud 5 Drain pipe 6 Bentonite 7 Acrylamide polymer flocculant 8 Tunnel 9 Mud type shield machine 10 Bulkhead 11 Mud pipe 12 Agitator 21 Mud film 22 Ground 23 Face 24 Mud water

Claims (5)

A face stabilization method in the shield method that keeps the stable state of the face,
A fine fraction and clay contained in the excavated soil, water, bentonite and, cutting face of the cutting face holding mud having permeability into the ground together with formulating only acrylamide polymer flocculant to agglomerate the particles of the bentonite By applying pressure to the face and infiltrating the ground from the face, the entire infiltration area of the ground infiltrated with the muddy water for retaining the face is improved and the solidification phenomenon is caused in the entire infiltration ground to have independence. The face stabilization method in the shield method characterized by A face stabilization method in the shield method according to claim 1,
  The face stabilization method in the shield method, wherein the acrylamide polymer flocculant has the form of a water-in-oil emulsion. It is a muddy water for holding the face in the shield method used in the face stabilization method in the shield method according to claim 1,
Only fine particles and clay contained in excavated ground, water, bentonite, and acrylamide polymer flocculant that aggregates the bentonite particles are blended, and has a permeability to the ground The muddy water for holding the face in the shield method. In the muddy water for holding the face in the shield method according to claim 3,
  A mud for retaining face in shield method, wherein the acrylamide polymer flocculant has a form of water-in-oil emulsion. In the mud for retaining face in the shield method according to claim 4,
The acrylamide polymer flocculent constituting the face retaining mud is a water- in- oil emulsion having a molecular weight of 1,000,000 or more and a dispersed particle size of an acrylic polymer having an ionization degree of 0 to 100 mol% of 100 μm or less. As a polymer flocculant having the form of:
Nonionic properties include polyacrylamide,
As an anionic property, a homopolymer such as acrylic acid, methacrylic acid, itaconic acid, maleic acid, acrylamide 2-methylpropane sulfonic acid, vinyl sulfonic acid, styrene sulfonic acid, or a copolymer with acrylamide,
Cationic properties include dimethylaminoethyl acrylate, dimethylaminopropyl methacrylate, acryloyl exciethyltrimethylammonium chloride, methacryloyloxyethyltrimethylammonium chloride, acryloylaminopropyltrimethylammonium chloride, methacryloylaminopropyltrimethylammonium chloride, acryloyl. 2-hydroxypropylide,
A muddy water for holding a face in a shield method, characterized by using either a homopolymer such as styrene or a copolymer with acrylamide.

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