JPH02283647A - Coating material for cast-in-place shield lining method - Google Patents

Abstract

PURPOSE:To obtain the subject material improved in strength by blending 2CaO.SiO2-containing quasi-belite cement with blast furnace slag, then adding a retarder and further a thickening agent, fluidizing agent and copper fibers and making quasi-belite cement-based hardening material having specific performance. CONSTITUTION:About 400kg/m<3> cement mixture prepared by adding a retarder to quasi-belite cement containing >= about 45wt.% 2CaO.SiO2 and >= the same amount of blast furnace slag is blended with aggregate comprising about 640kg/m<3> ground stone and about 1,020kg/m<3> sea sand, about 198kg/m<3> water, about 2kg/m<3> thickening agent such as water-soluble polyacrylic polymer compound, about 6kg/m<3> fluidizing agent such as sodium polycarbonate and about 95kg/m<3> copper fibers to give a coating material for cast-in-place shield lining method having <=1/5 the rise in temperature by hydration heat of Portland cement and >=12 hours final setting time after mixing. The same coating material is obtained by using a cement mixture of 70wt.% quasi-belite cement and 30wt.% fly ash instead of mixing of blast furnace slag.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a cement lining material used in a cast-in-place shield lining method used in tunnel shield construction.

[Conventional technology]

In the conventional shield construction method, the inside of the tail plate at the rear of the shield machine is used as the outer shape, and a formwork whose outside diameter is the finished inside diameter of the tunnel is assembled inside this, and a stop formwork is installed at the tip of the tunnel in the excavation direction. A method called the cast-in-place shield lining method (specially cast-in-place shield lining method), in which the tunnel is lined with one concrete pour by placing concrete using the pump pouring method in the space between the tip of the poured lining concrete. (Refer to Japanese Patent Publication No. 109498/1983) was developed, but the lining material used in this construction method is not particularly limited.

In addition, as a backfill injection material for shielding, a cementitious solidifying material whose setting start time is adjusted to 12 to 48 hours after mixing is mixed with a thickening agent and a fluidizing agent (JP-A-6
2-148353) is known.

[Problem to be solved by the invention]

According to the conventional cast-in-place shield lining method,
(1) A cold joint occurs between the edge of already hardened concrete and newly poured concrete.

(2) At a distance of about 5 m to 15 m from the tail of the shield machine, the rocking of the formwork due to the thrust of the excavation jack of the shield machine is applied to the lining concrete, so that cold joints may develop into cracks. (3) Due to the expansion of concrete due to the heat of hydration of the cement, and the subsequent contraction due to cooling, drying, and carbonation, cracks expand over time and cause water leakage. (4) Due to (1), (2), and (3) above, cracks in the circumferential direction and tensile stress in the same direction occur in the lining concrete, and the tensile strength and bending strength of the lining concrete are significantly reduced. (5) Since the lining concrete is cast using a pump method, it is necessary to clean the transport pipe after pouring is completed, which requires time and labor, and the remaining concrete in the transport pipe after pumping is finished. is discarded and wasted.

(6) If groundwater is present when placing lining concrete, the concrete will be washed away by water and separated, making it impossible to obtain high-quality lining material. (7) The flow resistance of the lining concrete increases over time, making it impossible to completely fill the space between the formwork and the excavated ground. (8) The conventional shielding backfill injection material is effective in preventing cracks in only the backfill material, but it is not possible to prevent cracks in the entire lining concrete, prevent cracks from expanding, and completely prevent water leakage. There were problems such as not being able to do so. This invention aims to solve these problems.

[Means to solve the problem]

In order to solve the above-mentioned problems, this invention
Mix quasi-verit cement containing 45% or more of t(h with at least the same amount of granulated water as quasi-verit cement, and add a retarder to this, or quasi-verit cement 70 containing 45% or more of 2CaO・Sing. % or more and 30% or less of fly ash, and by adding a retarder to this, the temperature rise due to the heat of hydration is adjusted to 175 or less than that of ordinary Portland cement, and the final setting time is adjusted to 12 hours or more after mixing. Introducing a lining material for the cast-in-place shield lining method, which is made by adding a water-soluble acrylic polymer compound disease control agent, a fluidizing agent such as polycarboxylic acid sodium salt, and steel fiber to a verint cement-based solidified material. It is something.

[Effect]

(A) Regarding single-berit cement-based solidified materials, normal cement begins to undergo a hydration reaction approximately one hour after mixing, becoming viscous and less fluid, but it remains stable even when shaken before it finishes setting. There is no significant effect on the hydration reaction of cement. However, shaking that is applied after the lining material has lost its fluidity causes cracks to occur inside the lining material. To avoid this, quasi-verit cement [In this specification, quasi-verit cement refers to cement containing 2CaO-5ift (hereinafter referred to as C2S) as its main component (containing 45% or more). ] It is effective to use a solidified material.

(a) As a quasi-verit cement solidification material, C2S
A mixture of quasi-verit cement containing 45% or more of quasi-verit cement with at least the same amount of granulated water as the quasi-verit cement, and a retarder or retarded fluidizing agent added thereto is used. This solidified material has properties that not only the hydration reaction is extremely slow and the heat of hydration is extremely small, but also the carbonation reaction is small.

In other words, the 3Cs that make up the main body of ordinary Portland cement
While aO-Si(h (hereinafter referred to as C and S) completes the hydration reaction in about 7 days, CZS
starts a full-scale hydration reaction after 6 days of age, and the mixed granulated water does not start its hydration reaction until the hydration reaction of quasi-verit cement progresses to a certain extent.

The heat of hydration of CtS is as low as about 50% of that of C3S.
In particular, the heat of hydration of Cps is extremely small, about 20%, until about 7 days old.

Therefore, as shown in Table 3, when using till portland cement, the temperature rise of concrete due to the heat of hydration after subtracting the heat radiation from the concrete surface is about 30°C, whereas it contains 45% C25. Semi-verit cement mixed with the same amount of granulated water has a temperature of about 1° to 6°C (see studs), which means that the temperature rise due to the heat of hydration generated by semi-verit cement is 175 or less than that of ordinary Portland cement. This indicates that the shrinkage of concrete during hardening and cooling due to aging is correspondingly small, and there is no need to worry about a decrease in concrete strength, especially tensile strength and bending strength, or cracking. do not have.

In addition, the amount of calcium hydroxide produced by hydration of C2S is 21.5%, which is significantly smaller than 48.7% in C1S, and since there is no release of calcium hydroxide from hydration of granulated water, quasi-berit cement Carbonation of the solidified material is significantly less than that of ordinary Portland cement, and there is no decrease in strength or occurrence of cracks due to this.

The final setting time of the quasi-verit cement solidified material can be adjusted by adding a retarding superplasticizer and increasing or decreasing the proportion of C2S contained in the quasi-verit cement or the mixing ratio of the quasi-verit cement and granulated water as shown in Table 1. can be adjusted to

Table 1 Note +11 The semi-vegetable material of this invention in which 1% of the amount of cement is mixed with polycarboxylic acid sodium salt as a retarding fluidizing agent (2) A retarder alone may be used instead of the retarding fluidizing agent. Since the cement-based lining material is mixed and adjusted to have a setting completion time of 11 tons and 12 hours or more, it is 5 m to 15 m from the tail of the shield machine (corresponding to a work amount of 12 hours or more and 48 hours from the start of excavation by the shield machine). Until now, the formwork was shaking due to the thrust of the shield excavation jack, but during this time the lining material was not solidified, so no cracks would occur even if it was shaken. In addition, the quasi-verit cement-based solidified material does not set for more than 12 hours, and the lining material contains a fluidizing agent, so it maintains its fluidity for more than 24 hours, so it can be left as it is after pumping the lining concrete. It is possible to install the pump again the next day. Furthermore, lining concrete work requires several hours of waiting time between each excavation of the shield machine, but since the concrete to be placed later is placed before the concrete that has already been placed has finished setting, it is cold at the boundary between the two. Joints do not occur.

(b) C2S as quasi-verit cement solidification material 4
It is possible to use a mixture of 70% or more of quasi-verit cement containing 5% or more and 30% or less of fly ash, to which a retarder is added.

In this case, as in the case of (a) above, the temperature increase due to the heat of hydration is about 1" to 6", which is less than 115 that of ordinary Portland cement, and the setting completion time is 12 hours or more after mixing, and the flow Fluidity is maintained for 24 hours or more by mixing a curing agent.

(B) In the case of quasi-veritable cement-based solidified materials with delayed setting of thickeners, solid content continues to settle and breathe over a long period of time, and moisture accumulates in the upper part of the poured concrete lining, causing that area to deteriorate. Later, it becomes a void and makes it easier for the ground around the shield to subside.

To avoid this, it is effective to add a thickening agent. Thickening agents not only improve the uniformity of placed lining concrete by preventing solid content from settling and breathing, but also improve the uniformity of lining concrete that remains in the transport pipe due to pumping. Maintain uniformity even if
The work of re-pumping the lining concrete remaining in the transport pipe for about an hour can be carried out without any problem.

In addition, since the viscosity of the lining concrete is increased, even if the lining concrete that has been press-fitted encounters groundwater, the cement will not be washed away by the water, resulting in completely homogeneous place casting even in areas where groundwater exists. The shield lining method can be used without leaving any voids above the lined concrete.

(C) About the superplasticizer, quasi-verit cement mainly composed of Cts contains 15 C3S.
% to 30%, and the flow resistance increases after several hours after mixing, but since the concrete for lining of this invention has a fluidizing agent added, it is difficult to formwork and shield excavated ground. Not only can it easily and completely fill the space between mountains, but it can also be easily transported about 100 meters by pumping.
Concrete maintains fluidity close to the initial level for about 24 hours after mixing. Therefore, even if the lining concrete work interval is about 6 to 24 hours, there is no need to clean the inside of the pressure pipe or to discard the concrete remaining inside the pipe.

In addition, since a fluidizing agent is added, it is possible to reduce the water-cement ratio to around 50% to 40% while ensuring the necessary fluidity, increasing the strength of concrete and achieving high quality. of concrete can be obtained.

(D) Regarding steel fibers The lining material of this invention has extremely low expansion of concrete due to the heat of hydration of cement, shrinkage due to subsequent cooling, shrinkage due to drying and carbonation, etc. Minute cracks may occur when a product is exposed to various adverse conditions, such as being exposed to vibrations due to earthquakes or other causes, and - once cracks occur, they may expand over time and cause water leakage. However, to avoid this, it is effective to mix steel fibers.

Cement-based solidified materials reinforced with steel fibers are extremely strong, with greater tensile strength, bending strength, shear strength, and durability than those made using only ordinary concrete, so they are used in place of reinforcing bars when they cannot be used. However, especially in the lining material of this invention, the crack initiation stress increases by 40% due to the inclusion of steel fibers, making it strong and having extremely low elongation, which prevents cracks from occurring.
Even if cracks occur, they can be prevented from expanding more reliably,
Therefore, occurrence of water leakage can be prevented.

〔Example〕

Examples of the lining material for the cast-in-place shield lining method of the present invention are shown in Table 2.

In addition, a concrete block with the composition of Example 1 was made,
Table 3 shows the measured values of the temperature rise due to the heat of hydration.

〔Effect of the invention〕

The lining material of the present invention has a temperature rise due to heat of hydration of 175 below that of ordinary Portland cement, and a setting completion time of 12 hours or more after mixing. Because it does not set, there are no cracks or cold joints that occur in the lining concrete when shaking is applied after setting, and cracks do not expand and cause water leaks. Since the fluidity remains for a long time, the void between the formwork and the ground excavated by the shield machine is completely filled, and because it has a viscosity, the quality of the filled concrete will not deteriorate even if there is groundwater, and the excavation can be carried out. No ground subsidence will occur.

Furthermore, there is no need to clean the inside of the transport pipe immediately after pumping the lining concrete, which saves labor costs, and there is no need to dispose of the concrete remaining inside the transport pipe, reducing wasted materials. do not have.

In particular, the lining material of this invention has a temperature rise due to heat of hydration that is controlled to be less than 175 that of ordinary Portland cement, so it generates almost no heat during curing, reducing the mechanical properties of the lining concrete during curing. Therefore, it performs as designed against compressive loads, bending loads, and shear loads that act on the lining concrete due to earth pressure from other mountains after construction, as well as tensile loads due to temperature changes inside the tunnel. However, it is effective in preventing decreases in the strength of the lining concrete during hardening, particularly in bending strength and tensile strength, which was not achieved with conventional cast-in-place shield lining construction methods, and in preventing water leakage due to cracks.

Agent Patent Attorney Kiyoshi Sakai Procedural Amendment May 2C, 1989 Director General of the Patent Office Yoshi 1) Tsuyoshi Moon 1, Indication of the case 1999 Patent Application No. 101754 2, Name of the invention For cast-in-place shield lining construction method Lining material 3, relationship with the case of the person making the amendment Patent applicant address: 3-21-16 Kugahara, Ota-ku, Tokyo Name
Yukio Naito 4, Agent 150 Telephone 49B-4720 Address 2-2-47 Shibuya, Shibuya-ku, Tokyo Column 8 for detailed explanation of the invention in the specification to be amended Contents of the amendment (1) Description “(
According to 3), the tensile strength of the lining concrete is corrected to the axial and circumferential tensile strength of the lining concrete according to (3).

(2) Correct "rcts 45%" on page 8, line 5 of the same book to "CCS 62%".

(3) In the same book, page 8, line 7, [semi-verit cement] is corrected to "semi-verit cement."

(4) In the same book, page 13, line 1 O, replace “to each” with “
Gradually correct it.

(5) “Significantly small,
is corrected to ``It's extremely small, but not completely absent.''

spontaneous correction)

Claims (1)

[Scope of Claims] 1. A cast-in-place shield lining made of a quasi-verit cement-based solidified material whose temperature rise due to heat of hydration is adjusted to 1/5 or less of that of ordinary Portland cement, and whose final setting time is adjusted to 12 hours or more after mixing. Lining material for construction methods. 2. The lining material for cast-in-place shield lining method according to claim 1, wherein the quasi-verit cement solidified material is a quasi-verit cement mixed with granulated water. 3. The quasi-verit cement solidified material is 2CaO・Si
The lining for the cast-in-place shield lining method according to claim 1 or 2, wherein quasi-verit cement containing 45% or more of O_2 is mixed with at least the same amount of granulated water as the quasi-verit cement, and a retardant is added thereto. material. 4. The quasi-verit cement solidified material is 2CaO・Si
70% semi-verit cement containing 45% or more O_2
The lining material for cast-in-place shield lining method according to claim 1, wherein 30% or less of fly ash is mixed with the above and a retardant is added thereto. 5. The lining material for cast-in-place shield lining method according to claim 1 or 3, wherein a thickening agent is added to the quasi-verit cement solidified material. 6. The lining material for cast-in-place shield lining method according to claim 1 or 3, wherein a fluidizing agent is added to the quasi-verit cement solidified material. 7. The lining material for cast-in-place shield lining method according to claim 1, 5 or 6, wherein steel fibers are added to the semi-verit cement solidified material. 8. The lining material for cast-in-place shield lining construction method according to claim 5, wherein the thickening agent is a water-soluble polyacrylic polymer compound. 9. The lining material for cast-in-place shield lining construction method according to claim 6, wherein the fluidizing agent is a polycarboxylic acid sodium salt.