JPS5927982A - Conditioning of ground - Google Patents

Abstract

PURPOSE:To condition the ground with an extended curing time of cement slurry without lowering its strength, by pouring into ground a mixture of an aqueous solution of alkali silicate with a slurry prepared by adding zinc carbonate and/or zinc oxide to cement. CONSTITUTION:In the conditioning of the ground with a combined use of cement and alkali silicate, a slurry prepared by adding zinc carbonate and/or zinc oxide to cement, is mixed with an aqueous solution of alkali silicate and the mixture is poured into ground. The slurry has a longer curing time than that not containing any retarder and is by no means inferior to it in uniaxial compressional strength.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for improving the ground 2a by injecting a grouting agent into soft ground, water leaking ground, ground behind a tunnel, etc. to strengthen the ground, prevent cave-ins, stop water, etc.

Conventionally, the grouting agents used in this type of construction method are alkaline silicate and gelling agent C1 bicarbonate) 7 alkali,
Solution type mainly composed of alkali bisulfate, alkali aluminate, etc., and gelling agent-bound C rethane 1 class or JI
It is divided into two types: a suspension type, which is mainly composed of water-insoluble powder of the t-men 1 type. The gunut agent used in the method of the present invention belongs to the suspended form, which is further divided into 5) A) Cemen 1 hesilicate alkali-water, B) Remen [-one slaked C] charcoal or raw coal-( i
It is represented by 34I+' of water.

A) is the so-called standard method, and the gel time used in the W method is 1 minute outside the wall. B) 1. L LW I
Improvements in the method (by adding slaked charcoal 1 and charcoal, the gel time was accelerated to 5 to 20 seconds to prevent glaucoma from escaping, and the initial strength of the corporate ground was increased. b
C. Yes. C) is the one used in backfill injection method 1, which is usually applied to Shield A. A foaming agent is added and the gel time is 1 to 30 seconds.The above typical ground improvement method is cement 1-1. Each ratio of water, t-mentho alkaline silicate,
Furthermore, although there are differences in various additives, there are basically those that utilize a gelation reaction between cement or additives and an aqueous alkali solution.

One problem with these lJ methods is that cement 1~
Due to their latent hydraulic properties, various types of mortar self-harden within a certain period of time, causing clogging of piping or solidification inside the pump during transport. Workability in the workplace may be impaired. Another problem C is that if the cement slurry is left as it is, the pouring operation becomes increasingly difficult due to thickening.

In the case of A> above, the cement slurry used in the standard mW method () has a large W/C (water/cement ratio) of 1
! In 1, particles of 1 to 1 rethane settle out in a short time, and such cement slurry has a relatively long self-hardening time, and when wet with a high
211: If 'within 1 hour', it is possible to practice again. However, if this is possible after a long period of standing, repeat ("
When mixed with an aqueous alkaline silicate solution and covered, the self-hardening phenomenon of the rethane particles progresses considerably, so local gelation occurs, the apparent gel time becomes faster, a non-uniform gel is formed, and the rise A phenomenon in which the strength decreased considerably was observed. 7th
11' The distance from the pump to the tip of the injection tube is relatively short, and the injection recycle is performed for a short period of time, so it is not possible to use standard L.
In the W method, no setting retardant is used, or when the temperature of the summer rethane 1 to the slurry is 10 degrees, it becomes necessary to use the self-hardening method 1 μ or steep m + this Ueno zuru no C.

In addition, in 13), since slaked coal 2 is added to Rethane 1 to Melary, the specific gravity of water is substantially reduced.
Furthermore, due to the effect of these additives on accelerating the curing of Menu 1-, the need for an IF setting retarder is greater than in Δ).

Next, we will concretely apply C) (in this case, we will install a backfill injection membrane width in the starting shaft of J5L on the subway, B or sewer embankment, and install it near the tip of the face at a distance of several meters to more than 1000 meters. C' backfilling agent is used to transport the grout by pumping.In other words, the transportation of the cloud is often extremely long distance, and due to the differences in the excavated ground at each site (
The speed of shield excavation is unstable due to the gap between springs, etc.). Due to these reasons, 1) the cement slurry is left stationary for several hours from the pump to the injection tip, gradually losing its dixotropy (pressurized fluidity), which impedes pumping of the cement slurry;

11) In order to prevent the above 1>, it becomes necessary to replace the cement slurry in the piping with water every time the injection is recycle, so if the injection is restarted or if the water is not replaced with cement slurry No. This work requires a scale (without a scale), which increases the time loss as the liquid delivery distance increases.
Work efficiency is reduced due to an imbalance between shield excavation speed and injection work.

111) In areas with poor ground, the excavation speed will drop significantly and the number of injections will decrease, so
The residence time of the slurry becomes longer and pipe cleaning becomes necessary. In addition, if a failure occurs in the pump, face equipment, etc. and 1 = 1, there is a risk that 111 or more slurry will remain in the piping.

As mentioned above, in the backfilling method to which C) is applied, it is particularly desirable to delay the setting of the slurry in Remen 1.

Conventionally, in this type of setting retarder, several compounds such as sugar and gluconic acid were mainly used. It has the disadvantage of lacking initial strength.

The present invention has been made in view of the above problems.
A ground improvement method characterized by mixing a slurry in which at least one of zinc carbonate and zinc oxide is added to hymento with an aqueous alkali silicate solution and injecting the mixture into the -C ground. There is a law C.

For example, the zinc carbonate used in the present invention has a 2Zη mark of 3°3〆η.
The chemical formula of (OH)2.H20 is C (as shown). Zn Co
3 can of course also be used. The desirable flow force n of these zinc carbonate or zinc oxide is 0.01 to 0.01 to cements.
5% weight. If C' is less than 0.01% by weight, the setting retardation effect is small, and if it exceeds 5% by weight, the retardation effect is good, but it is not practical or economical. General (The lifting platform applied to AB above is 0.01 to 2% by weight based on the cement, and when applied to C, it is 0.05 to 3% by weight based on the cement.)
The percentage of heavy nitric acid is good, but in consideration of μ spread effect and economical efficiency, it is generally preferable to have a minimum of 1 to 2 parts.

For example, in A, 80 parts by weight of cement, 160 parts by volume of water, and a predetermined amount of lead carbonate and/or zinc oxide (hereinafter referred to as retarder) are mixed, and this slurry is mixed with an aqueous alkali silicate solution ( 7i Pump approximately 200 parts of No. 3 sodium silicate diluted to 2 times the volume, and inject into the ground at the tip of the injection tube. Also, B smell C is cement]~80 car volume・
Part, Gluing (W-promoting agent (gypsum, calcium hydroxide, etc.) 2
Mix 0 to 30 small parts, 160 parts of water, and the specified amount of retardant, and mix this slurry with about 2 parts of the alkali citric acid aqueous solution of "-".
Inject 00 volume parts into the ground using the same method.

In addition, C smell (240 parts by weight of cement 1, 240 parts by weight of Talayzant, 340 parts by weight of water, a specified amount of retardant,
Add 2 to 3 parts by weight of a foaming agent to the colander to increase the air ratio to 30.5
Pump C pumps a suspension section with 1000 volumes of the slurry made 0% and a 100 volume section of the same aqueous solution of aluminum silicate as above.゛1 person'iu tip C segment I-dorsal T part injected.

These compounding examples are representative examples of the above construction methods.
There are various types of materials that vary depending on factors such as the nature of the ground or the required strength of the ground, and additives commonly used in this type of construction method, such as dispersants, extenders, and bolting agents, may be added to these. is free.

According to the method of the present invention, the lobby can be maintained for several hours to 1 day, and the lobby can be maintained at C.C.
And without changing the performance of Cement i~ slurry,
Therefore, water-soluble silicic acid: 1v can also be mixed at the tip of the injection tube (C) to improve the soil without causing any change in gel time or strength.Other effects of the present invention are listed below. There is C as follows.

1) Carbonated button, oxidized! II! In addition to lead compounds, there are a few non-toxic substances C, various H pre-compounds, or JH.
T! An inorganic compound (31) compound, etc.) used as a retardant during soil IN) and the environment that is envisaged in the case of IJ
It's probably a dyeing problem or the beef is 4c.

11) When using sugar, gluconic acid, etc.
The effect of retarding cement self-hardening (addition of a small amount of J is 'IIS?' is exerted, and the effect of zinc carbonate is particularly significant (approximately 4 of oil-cooled zinc In addition, the delay effect may vary due to slight changes in the amount added.

According to Bear J, this method is mainly effective for the backfilling method. In this case, it is necessary to spread this out (there is an effect of 11 C', and a large amount of grout is applied 8 times to 4 times).
Noshimen (Adjust Hess Rally L/i: 33 Il
6, UIL'+ (condensation IJ InoC' fl) It is possible to greatly improve the efficiency of the industry.

Examples and Comparative Examples A 1-slurry having the composition 1 shown in Table 1 was prepared.
．． 6. +2.24.20°C after 48 hours; B iJ
Z> / Low 1iQ was measured and lJ,,... (3 Experiments Nos. 1 to 7) The slurry from which the supernatant was removed before measurement was measured in Experiments Nos. 8 to '18. A cylinder made of plastic (N) with a diameter of 8 CI and a height of 8 CI, with a vertical center part 1, is
J) After taking it out, pull out the introvert from the top and after 1 minute,
The average diffusion distance of slurry spread over plastic (1)
Tomari reading flow II white doji lko.

Table 1, Table 2 (as shown below, go to Experiment No. 1-5
(LW method composition), No. 6. ．． 7 (improved LW method composition),
No. 8 to 14 (backfill method composition, foaming agent), No. 15
Differences in flow value, gel time, and -axial compressive strength are observed between the groups of ~18 (backfill method composition, no bubbles) due to the difference in composition, but each of the above 1! C in Y is the method of the present invention t
The self-hardening time of the mentoslurry became clear compared to that without the addition of a retarder. At the same time, in terms of gel time and -axis I line intensity within each group, no inferiority was observed in C compared with that without the addition of a retarder. Also, those using retardant C sugar (N(15°N01=
In I), the self-hardening time is 4 hours, which is different from that of the present invention, but when the cement 1 to slurry is left to stand at a -axial compressive strength of 1-7, its weight is lower.

Applicant: Osaka Soda Co., Ltd. Agent: Patent Attorney Toru Shijo

Claims (1)

[Claims] In order to improve ``C base a+'' using alkali silicate (71), a slurry in which at least one weight of zinc carbonate d5 and zinc oxide was added to remen 1 was mixed with an aqueous aqueous solution of alkali silicate. A ground improvement method characterized by mixing and injecting it into the C ground.