JPH0143797B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention injects a sodium silicate (water glass) grout agent into the soil and gels it, solidifying the soil particles to strengthen the soil and stabilize the soil by making it impermeable to liquids. It is about the method. It has been widely known that soil quality can be stabilized using a grout agent containing sodium silicate as a main ingredient. This grouting agent based on sodium silicate is roughly divided into two types: a cement-water glass suspension type and a solution type consisting of sodium silicate and an organic or inorganic water-soluble hardening agent. Ru. The former method may not be able to achieve an effective injection effect because the cement particles settle and separate over time or are filtered by soil particles and cannot penetrate deeply, but the latter method has a low viscosity and is a fine injection material. Since it can also be applied to granular soils, the latter is generally used more frequently. Note that some of these curing agents are instant-setting, making it difficult to adjust the gelling time, or that the gelling time may vary significantly with small changes in the amount added, and may contain other toxic substances. Many of them have drawbacks, such as a syneresis phenomenon occurring when they are injected into a pot as an aqueous solution together with sodium silicate, and a pot with sufficient unconfined compressive strength cannot be obtained. Furthermore, in recent years, for ground with a mixture of fine-grained soil and coarse-grained soil, suspension-type chemicals are injected to solidify the coarse particles, and then solution-type chemicals are injected to solidify the fine-grained soil. , a construction method in which the above-mentioned chemicals are used in combination has been adopted to integrate and stabilize the ground where various gaps of different density and density coexist. However, in the case of this construction method,
The solution-type injection agent that comes into contact with the gel produced by the injection of the suspension-type agent may be unable to solidify the soil particles due to the alkaline content eluted from the gel, or may be temporarily unable to solidify the soil particles. A serious drawback was that it redissolved several days after solidification. In view of the above-mentioned drawbacks of the conventional soil stabilization treatment method using a sodium silicate grouting agent, the present invention provides that the agent is non-toxic and that the gelation time can be easily adjusted. The gelation time can be adjusted arbitrarily from seconds to several tens of minutes, and there is no syneresis phenomenon, and regardless of the length of the gelation time, high unconfined compressive strength is always obtained, and it also has high water-stopping performance. In addition, the purpose is to provide a soil stabilization treatment method that does not prevent soil consolidation or cause re-dissolution after consolidation even when used in combination with a method that uses suspension-type injection agents. It has been done. Therefore, the gist of the present invention is a solution-type aqueous mixture containing sodium silicate, potassium aluminate, and a potassium salt or sodium salt other than potassium aluminate, the potassium aluminate content being 3 to 20% by weight. It consists in a soil stabilization treatment method characterized by injecting a liquid into the soil. The sodium silicate used in the present invention is also called water glass, and has been conventionally used to stabilize soil quality. The sodium silicate is used in the form of an aqueous solution, but the concentration of the sodium silicate used may be determined as appropriate depending on the condition of the pot to be injected and the purpose. For example,
When No. 3 sodium silicate based on JISK 1408 is used, the amount of No. 3 sodium silicate used is generally 10 to 75% by weight, preferably 15 to 60% by weight of the aqueous mixture. Further, as the sodium silicate, in addition to No. 3 sodium silicate, No. 1 sodium silicate and No. 2 sodium silicate are also suitably used. Potassium metaaluminate may be used as the potassium aluminate in the present invention, and these may be used as solids, and generally commercially available aqueous solutions containing potassium oxide as an impurity (concentration 40-50 % by weight) may be used. If the amount of potassium aluminate used is too small, the gelation of sodium silicate will not occur and the compressive strength will decrease, while if it is too large, it will be difficult to adjust the gel time. Potassium acid is preferably used in an amount of 3 to 20% by weight. Other curing agents used include potassium salts or sodium salts other than potassium aluminate (hereinafter referred to as alkali metal salts for convenience). Specific examples of potassium salts include potassium chloride, potassium sulfate, acidic potassium sulfate, potassium nitrate,
Inorganic potassium salts such as potassium carbonate, potassium bicarbonate, potassium borate, potassium oxalate, potassium tartrate, potassium citrate, potassium formate,
Examples include organic potassium salts such as potassium acetate. Specific examples of sodium salts include sodium chloride, sodium sulfate, acidic sodium sulfate,
Inorganic sodium salts such as sodium nitrate, sodium carbonate, sodium bicarbonate, sodium borate, sodium aluminate, sodium oxalate,
Examples include organic sodium salts such as sodium chlorate, sodium citrate, sodium formate, and sodium acetate. These are used alone or in an appropriate mixture, generally in an aqueous mixture, and generally in an amount accounting for 2 to 20% by weight in the aqueous mixture. The gelation time of the aqueous liquid mixture in the present invention can be adjusted by adjusting the amount of potassium aluminate or the amount of alkali metal salt added thereto, but it can also be adjusted by changing the amount of sodium silicate. It can also be adjusted. In particular, a method in which the amount of potassium aluminate and alkali metal salt added is kept constant and the gelation time is adjusted by changing the concentration of sodium silicate is a method that allows the adjustment of the gelation time to be performed with good reproducibility. It is preferable because a constant high compressive strength can always be obtained regardless of length. In the present invention, in order to prepare the aqueous liquid mixture containing the above-mentioned sodium silicate, potassium aluminate, and alkali metal salt, these three substances and water may be added together to form an aqueous liquid mixture. Alternatively, an aqueous solution of sodium silicate at an appropriate concentration and an aqueous solution of potassium aluminate and an alkali metal salt prepared elsewhere may be added together. However, it is necessary that the aqueous mixture does not undergo gelation before injection. Therefore, in order to stabilize the soil according to the present invention, an aqueous liquid mixture containing the sodium silicate, potassium aluminate, and the alkali metal salt is injected into the soil to be stabilized. By doing this, the aqueous sodium silicate solution gels in the soil pot, solidifying the soil particles and making the area impermeable to water, thereby achieving soil stabilization. In the present invention, there are no particular restrictions on the method or device for injecting the injection liquid into the soil, and any injection method or device may be used, but the accuracy of the curing time In order to ensure this, it is preferable to transport the sodium silicate aqueous solution and the hardening agent aqueous solution of a predetermined concentration separately, for example, using an injection pump, mix them in a Y-shaped pipe, etc. immediately before or at the time of injection, and inject the mixture into the pot. . The method of the present invention is as described above, and is characterized by injecting into the clay an aqueous mixture containing sodium silicate, potassium aluminate, and an alkali metal salt, so it is safe. The conditions of high compatibility and ease of handling are satisfied, and the gelation time can be easily adjusted by adjusting the amounts of the above components in the mixed solution, and there may be some variation in the composition of the injection solution components. However, large fluctuations in gelation time can be kept to a minimum. Furthermore, according to the present invention, regardless of the length of the gelation time, it is possible to always exhibit a high level of unconfined compressive strength and high water-stopping performance, and the syneresis of the gelled product is also small. Even if the soil stabilization method using a suspension-type injection agent is used in combination with the construction method of the present invention, alkaline components may be eluted from the gel produced by the suspension-type injection agent, and the consolidation of soil particles by the aqueous mixture may be hindered. This prevents the solidified portion from redissolving over time. Next, examples and comparative examples of the present invention will be described. In the following, "parts" simply means parts by weight. Example 1 An aqueous solution (hereinafter referred to as liquid A) consisting of 70 parts of No. 1 sodium silicate and 50 parts of water based on JISK1408, 10 parts of potassium aluminate, and 5 parts of sodium carbonate was mixed with water.
An aqueous solution (hereinafter referred to as Solution B) in which 95 parts of the solution was dissolved was prepared. After adjusting the temperature of liquids A and B to 20℃, liquids A and B were added at a volume ratio of 1:1 and the gelation time was measured. It was hot in minutes and 30 seconds. Next, 100 parts of a mixture of liquid A and liquid B mixed at a volume ratio of 1:1 was infiltrated into 250 parts of Tohoho standard sand and tamped and hardened to a porosity of 40%.
This cured product was cured in wet sand for 7 days and then measured, and found to have a hydraulic conductivity of 7×10 ^-7 cm/sec and an unconfined compressive strength of 6.5 Kg/cm ² . Examples 2 to 7, Comparative Examples 1 and 2 Take the amount of each component shown as the B liquid composition in Table 1 and add water.
Prepare 100 parts of an aqueous solution (solution B), adjust the temperature of solutions A and B prepared in Example 1 to 20°C, and then add solutions A and B of the same volume to form a gel. When the curing time was measured, it was as shown in Table 1. In addition, the gelled product thus obtained was placed in a sealed container and stored in a constant temperature room at 20°C for 24 hours, and syneresis was measured by measuring the syneresis water separated from the gelled product. The results shown in the table were obtained.

[Table] Example 8, Comparative Example 3 When 100 c.c. of the suspension-type injection of the following formulation was placed in a 250 c.c. glass beaker and gelled, the gelation time was 2 minutes and 35 seconds. Ta. A total of 200 c.c. JIS No. 1 Sodium Silicate 230 parts Water 50 parts B Liquid Total of 200 c.c. Injecting agent 100 c.c. is flowed into the upper part of the gel in the beaker to form a gel,
When the contact surface between the gel produced by the suspension-type injection and the gel produced by the solution-type injection was observed, no abnormality was observed as shown in Table 2. Next, for comparison (Comparative Example 3), using 100 c.c. of the solution-type injection formulation of Comparative Example 1, approximately 100 c.c. of gel was obtained by the solution-type injection agent in the same manner as above, and two types of gels were obtained. When the contact surface of the gel was observed, as shown in Table 2, it was found that it was practically impossible to use the solution-type injection in combination with the above-mentioned suspension-type injection.

[Table] Example 9, Comparative Example 4 Water was added to each amount of No. 1 sodium silicate based on JISK1408 shown on the horizontal axis of Figure 1 to make 100 c.c. Sodium silicate with various concentrations Aqueous solution (A liquid) 100
cc, 5 parts of sodium carbonate, potassium aluminate
100 cc of an aqueous solution (solution B) prepared by dissolving 10 parts in 95 parts of water was mixed, and the gelation time was measured at 20°C. On the other hand, for comparison (Comparative Example 4), the same A liquid 100c.c.
The mixture was mixed with 100 c.c. of an aqueous solution (solution B) in which 7.5 parts of sodium aluminate was dissolved in 95 parts of water, and the gelation time was measured. As a result, as shown in FIG. 1, it was found that there was a clear correlation between the sodium silicate concentration in liquid A and the gelation time in the example, and that the gelation time could be easily adjusted. The relationship between sodium silicate concentration and gelation time was complicated, and it was difficult to adjust the gelation time. Example 10, Comparative Example 5 A liquid mixture of equal volume of liquid A and liquid B having the following composition was prepared. No foreign matter such as white precipitate was generated in the mixed solution. A total of 200 c.c. JIS No. 1 Sodium silicate 150 c.c. Water 50 c.c. B component Total of 200 c.c. The amount of potassium aluminate is as shown in Table 3. Sodium carbonate 10 g Water Remaining 5 cm in diameter and 10 cm in length Toyoura standard sand was placed in a mold and compacted to a porosity of 40%, and the above-mentioned aqueous mixture immediately after mixing was injected under pressure at an injection pressure of 2 kg/cm ² to obtain a sand gel. There were no operational problems. After curing this sand gel in a mold for one day, it was demolded and the unconfined compressive strength was measured, and the results were as shown in Table 3 and FIG. 2. For comparison (Comparative Example 5), 200 c.c. of liquid A used in Example 10 and 200 c.c. of liquid B in which sodium aluminate was used in place of potassium aluminate in the same liquid B in the proportions listed in Table 3. An injection solution with the same gel time as in Example 10 was prepared. Both solutions A and B were mixed, and standard sand was poured in the same manner as in Example 10 to obtain a sand gel. The measurement results of the unconfined compressive strength were as shown in Table 3 and FIG. As described above, according to the present invention in which potassium aluminate and sodium carbonate are used in combination, the strength can be greatly improved at the same gel time compared to the case in which sodium aluminate and sodium carbonate are used in combination. it is obvious.

【table】 [Brief explanation of drawings]

FIG. 1 is a correlation diagram showing the relationship between the aqueous concentration of sodium silicate used in each of the grafting agents in Example 9 and Comparative Example 4 and the gelation time;
The figure is a diagram showing the relationship between gel time and unconfined compressive strength in Example 10 and Comparative Example 5.

Claims (1)

[Claims] 1. Injecting into the clay a solution-type aqueous mixture containing sodium silicate, potassium aluminate, and a potassium salt or sodium salt other than potassium aluminate, with a potassium aluminate content of 3 to 20% by weight. A soil stabilization treatment method characterized by: