JPH0820776A - Recycle of surplus soil of excavation - Google Patents

Abstract

PURPOSE:To obtain a good refilling material simply and easily. CONSTITUTION:A method for recycling surplus soil of excavation having a high water content and obtained in civil engineering and construction works by modifying the properties of the soil by adding a soil conditioner to the soil and curing the mixture, wherein the step of adding the conditioner comprises a combination of the steps of (a) adding a setting accelerator, (b) adding a water-absorbing polymer, (c) adding quick lime, and (d) adding a cement-base hardener and wherein the order of these steps is (a), (b), (c) and (d) or the step (i) of adding a mixture comprising a setting accelerator and a water-absorbing polymer and the step (ii) of adding quick lime and a cement-base hardener. It is desirable that the setting accelerator be water glass.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for reusing excavated residual soil having a high water content, and more particularly to a method for reusing excavated residual soil having a high water content obtained in civil engineering construction work.

[0002]

2. Description of the Related Art Conventionally, when a power transmission line is buried in the ground, depending on its location, it may be buried in a soft ground such as the seabed, sandy soil with high moisture content, cohesive soil, etc. Since the obtained excavated soil has muddy fluidity and is difficult to backfill, such excavated soil has hitherto been discarded.

[0003]

However, in recent years,
It is difficult to secure a disposal site for the excavated residual soil obtained from the soft ground as described above, and it is desirable to process and reuse the excavated residual soil from the viewpoint of preventing natural destruction due to disposal of the excavated residual soil and environmental protection. However, it has been attempted to improve the soil quality of the excavated residual soil by using so-called cement-based solidifying material and reuse it, but it is not applicable to a wide range of soil types, and the soil quality that can be practically used in construction There is no improvement material and therefore there is a strong demand for the improvement. Therefore, the present inventors have conducted various studies and researches on these points, and as a result of continuing the research from the viewpoint of reusing the excavated residual soil, as a result, added some kind of auxiliary agent and solidifying agent to the excavated residual soil. It was found that a so-called sandy aggregated product having an apparently small water content and being aggregated can be obtained by mixing by mixing with each other, and the present invention has been completed here. Therefore, it is a first object of the present invention to provide a method for reusing excavated soil so that the excavated soil obtained in civil engineering construction work can be used as a backfill material. A second object of the present invention is to provide a method for recycling excavated soil so that a good backfill material can be obtained simply and easily.

[0004]

The respective objects of the present invention are as follows.
The present invention can be achieved by the following inventions. (1) In the method of reusing the excavation residual soil by improving the soil quality of the excavation residual soil by adding and mixing the soil improvement agent to the excavation residual soil having a high water content obtained in the civil engineering construction work and then curing The addition and mixing process of the materials includes (a) addition and mixing process of setting accelerator, (b) addition and mixing process of water absorbing polymer, (c) addition and mixing process of quicklime and (d) addition and mixing process of cement hardening agent. A method for reusing excavated residual soil, which is characterized by comprising a combination. (2) Soil conditioner addition and mixing step includes (a) setting accelerator addition and mixing step, (b) water absorbing polymer addition and mixing step, (c) quicklime addition and mixing step, and (d) cement-based hardening agent. The method for reusing the excavated residual soil according to the above-mentioned item 1, which is performed in the order of the addition and mixing step. (3) The addition and mixing step of the soil conditioner includes (a) the addition and mixing step of the mixture of the setting accelerator and the water-absorbing polymer,
(B) A method for reusing excavated soil, which comprises a combination of addition and mixing steps of quick lime and a cement-based hardening agent in any order. (4) The method of reusing the excavated soil according to the item 1 or 2, wherein the setting accelerator is water glass.

The present invention will be described in more detail below. In the method for reusing excavated soil according to the present invention, a setting accelerator, a water-absorbing polymer, quick lime and a cement-based hardening agent are used as soil improving agents. The soil conditioner can be added in any order to the excavated soil residual soil by adding a setting accelerator, a water-absorbing polymer, quicklime and a cement-based hardening agent in this order, and the water-absorbing polymer, setting accelerator, quicklime and a cement-based hardening agent are added in any order. Or quicklime, cement-based hardening agent, setting accelerator, water-absorbing polymer, then quicklime, cement-based hardening agent,
The order of the water-absorbent polymer and the setting accelerator may be followed by the order of the cement-based hardening agent, quick lime, the water-absorbing polymer and the setting accelerator. Preferably, the setting accelerator, the water-absorbing polymer, quicklime and the cement-based hardening agent are added and mixed in this order. Further, a mixture of a setting accelerator and a water-absorbing polymer (this mixture may be referred to as an auxiliary agent) and a mixture of quick lime and a cement-based hardening agent (this mixture may be referred to as a solidifying agent). Divide into groups to form a mixture, add this to the excavated soil and mix with
Then, a solidifying agent may be added and mixed, or vice versa. By using the four types of soil-improving materials in this manner, the soft soil quality is changed to a sandy, free-flowing, aggregated soil quality, and therefore an extremely excellent backfill material can be obtained.

In the method of reusing the excavated soil of the present invention, the method of the third item is preferable to the method of the second item which has a large number of steps in construction work. Therefore, each soil improvement agent is used by the method of the second item. It is desirable to find the mixture ratio of the optimum addition mixture ratio of the above and the excavated residual soil to be treated, and use the auxiliary agent and the solidifying agent prepared based on this to perform the construction. The setting accelerator used in the present invention is preferably water glass, and the water-absorbing polymer is starch-based, cellulose-based or synthetic resin such as acrylamide, acrylic acid and acrylate. Preferred is a crosslinked body of a water-absorbing polymer containing an alkali salt of acrylic acid as a constituent. The solidifying material used in the present invention includes quick lime, and the cement-based solidifying agent may be a conventionally known one, which is produced by adding blast furnace slag, slaked lime, gypsum or the like to cement. Portland cement or the like is usually used as the cement.

The auxiliary agent used in the present invention is composed of water glass and a water-absorbing polymer, and the mixing ratio of these to the excavated soil having a high water content depends on the water content of the excavated soil, but 100 parts by weight of the excavated soil. On the other hand, water glass is 0.01 to 10 parts by weight, preferably 0.5 to 5 parts by weight. Eventually, this water glass will react with the cementitious solidifying material to obtain strength in a short time to form aggregates, and the strength of the aggregates will also increase. Further, the amount of the water-absorbent polymer is 0.005 to 5 parts by weight, preferably 0.01 to 0.5 parts by weight, based on 100 parts by weight of the excavated soil. The water-absorbing polymer may be added in a small amount, and the polymer easily dissolves in water in the excavated soil, and the water-absorbing / thickening action of the polymer causes the excavated soil containing the water glass and the polymer to remain unexposed. The water content seems to be lower than that of the treated soil.

Next, in the present invention, after the auxiliary agent is added, it is thoroughly mixed and quicklime and a cement-based solidifying agent are added as a solidifying material. The addition ratio of quicklime is 100% of excavated soil
Quick lime is 0.5 to 15 parts by weight, preferably 2 to 10 parts by weight, based on parts by weight. By adding this quicklime, excavated soil is aggregated. The proportion of the cement-based solidifying agent added subsequently is 1 to 30 parts by weight, preferably 3 to 15 parts by weight, relative to 100 parts by weight of the excavated soil. This cement-based solidifying agent is present in the form of covering the aggregated material of the excavated soil. As a result, the cement-based solidifying agent reacts with water glass in the coated portion to obtain strength in a short time to form aggregates, and the strength of the aggregates is also increased. The excavated soil treated in this way is
It is preferably cured. As a result of this curing, the hydration reaction of the cement proceeds, and as the curing period elapses, the strength of the coated portion of the cement-based solidifying agent increases, and the aggregate becomes stronger.

In the ratio of each component to the excavated soil,
If the addition ratio of water glass is less than 0.01 part by weight, the reaction with the cement-based solidifying agent is weak and there is no substantial effect, and if it exceeds 10 parts by weight, the cost is high for the effect and it is economically disadvantageous. Further, if the addition ratio of the water-absorbing polymer is less than 0.005 parts by weight, there is no sufficient water-absorbing effect, and if it exceeds 5 parts by weight, there is no further effect on the water-absorbing performance and it is economically disadvantageous. If the addition ratio of quick lime is less than 0.5 parts by weight, the agglomeration is insufficient and the addition ratio of quick lime is 15
It is economically disadvantageous because the effect does not change even if it exceeds the weight part. Further, if the addition ratio of the cement-based solidifying agent is less than 1 part by weight, sufficient strength cannot be obtained in the coated portion of the cement-based solidifying agent, and even if it exceeds 30 parts by weight, the aggregates easily adhere to each other, The re-drillability deteriorates.

The soil suitable for the method for reusing the remaining excavated soil of the present invention is mixed with silt, sandy soil having a high water content, cohesive soil, sea sand, etc., so that fine-grained soil is aggregated in a short time. It can be changed to sandy soil, and the obtained soil has high performance of high permeability and high strength. The method for reusing excavated soil according to the present invention is used as a backfill material by utilizing such performance to improve the soil quality generated in civil engineering construction work.

[0011]

In the method for reusing excavated soil according to the present invention, by adding water glass to excavated soil having a high water content, hydrates such as calcium silicate can be obtained for a long time by reacting with calcium in the cement-based solidifying material. Generates and enhances strength. Further, the water-absorbent polymer absorbs water from the excavated residual soil containing water and changes into a free-flowing soil. The soil remaining after excavation is aggregated by adding quick lime. Further, by adding a cement-based solidifying material, the aggregate is aggregated, the particles of the aggregated product are covered, and the strength of the aggregated product is increased in a short time due to the reaction between the cement-based solidifying agent and water glass in the coated portion.

[0012]

EXAMPLES The present invention will now be described in more detail with reference to examples, but the present invention is not limited to these examples.

Example 1 1.0 part by weight of water glass was added and mixed with 100 parts by weight of excavated soil having a high water content obtained in the construction work of an underground power transmission line. Then, 0.05 part by weight of a water-absorbent polymer was added to and mixed with the obtained excavated soil. Next, 6.0 parts by weight of Stabilite M15 (manufactured by Mitsubishi Materials Corp., cementitious solidifying material) was added as a cementitious hardening agent and mixed sufficiently. 3.0 parts by weight of quick lime is added to the finally obtained excavated soil mixture to aggregate the treated soil. Soil data of excavated soil before mixing (moisture content, grain size, CBR)
Further, soil data (75 μm passage rate, CBR, agglomeration) after mixing treatment using the solidifying mixture by the method of the present invention are shown in Table 1 as Example 1-1 to Example 1-7. Table 1
As is clear from the above, by treating the high-moisture content soil to be dumped as industrial waste by using the method of the present invention, it can be used as a material for road bodies and subgrades in a short time. The strength is such that it can be backfilled, and it becomes a state like dry sand that is easy to scatter.

[0014]

[Table 1]

Example 2 Several types of soil and water were mixed to prepare soils having different particle sizes and water contents, which were used as sample soils. About the sample soil, an auxiliary agent (composition 10) consisting of water glass and water-absorbing polymer in parts by weight.
0: 3.2) 1.05 parts by weight were added and mixed, and then the main agent (composition ratio 10
0:43) 9.0 parts by weight were added and mixed. The soil data (moisture content ratio, grain size) of the sample soil before the mixing treatment and the soil data after the mixing treatment using the method of the present invention (75 μm passage rate, CBR, agglomeration) are carried out in Examples 2-1 to 2-1. Example 2-9
As shown in Table 2, as is apparent from Table 2, even if a mixture of two sets of an auxiliary agent and a main agent is used, the properties are close to those of Example 1, and the process in practical construction can be simplified. .

[0016]

[Table 2]

Example 3 The treated soil 3 mixed and processed by the method of the present invention is pipes 21 to 21.
No. 26, and whether it can be used as a backfill material around the pipe was tested using the container 1 of FIG. The container 1 for this test uses a transparent acrylic plate and has a length of 500 mm and a width of 9
The container was 92 mm × height 706 mm, and water drainage holes were provided on the bottom surface at a pitch of 30 mm and a pitch of 120 mm. A punching sheet (diameter: 2 mm, pitch: 5 mm) was laid on the bottom surface to prevent soil particles from being washed away. On the other hand, the outer diameter and the arrangement of the simulated pipes 21 to 26 are such that the diameter of the simulated pipe is 1
50 mm, arranged in 3 rows and 2 stages. Adjacent tube distance is 56m
The distance between the side wall and the tube was 215 mm. The treated soil 3 was prepared by the same addition method and rate as in Example 2. After treating the treated soil for 3 hours, it was put into a container, the filling condition was observed by tightening with water, and the other properties were tested. Table 3 shows the results. As is clear from Table 3, as a result of water tightening, the fillability of the treated soil around the pipes was good, and the strength also showed a sufficient value, so as a backfill material on the pipes 21 to 26 and around the pipes. It can be said that the use of is sufficiently possible. In addition, as a comparison, Table 4 shows the evaluation of the sandy soil mixed with 2 parts by weight of quick lime and mixed with the cohesive soil mixed with 10 parts by weight of quick lime. As is clear from Table 4, for sandy soil, a bearing capacity of 20 parts or more of CBR can be obtained, but when water-tightened, both sandy soil and cohesive soil become muddy and unsuitable as a backfill material around pipes. Met. On the other hand, in the method of the present invention, both sandy soil and cohesive soil
Within 4 hours, the CBR was 20 parts or more, and even after tightening with water, it did not become muddy and kept granular.

[0018]

[Table 3]

[0019]

[Table 4]

[0020]

INDUSTRIAL APPLICABILITY According to the method of the present invention, water glass, absorbent polymer, quick lime and cement-based solidifying agent are added to this excavated soil in this order or in any order to mix them, so that water permeability in a short time is obtained. It is possible to use excavated soil obtained from civil engineering construction work such as underground power lines as a backfill material and it is easy and easy to obtain because it can obtain agglomerated products of excellent A backfill material is obtained.

[Brief description of drawings]

FIG. 1 is a perspective view showing a treated soil test apparatus required for a method for reusing excavated soil according to the present invention.

[Explanation of symbols]

 1 Test container 21-26 Simulated pipe 3 Soil processed by mixing

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location C09K 17/50 P E02D 3/00 E02F 7/00 D // (C04B 28/10 24:26) E C09K 103: 00 (72) Inventor Tadaaki Tsuno 2-9-18 Honjo Higashi, Kita-ku, Osaka City, Osaka Prefecture Kanden Kogyo Co., Ltd. (72) Hiroshi Ueno 2--9 Honjo Higashi, Kita-ku, Osaka City, Osaka Prefecture No. 18 KANDEN Kogyo Co., Ltd. (72) Inventor Junji Nakamura 1-8-17 Umeda, Kita-ku, Osaka-shi, Osaka Sanryo Materials Co., Ltd.Osaka branch office (72) Inventor Eiji Domoto Umeda, Kita-ku, Osaka-shi, Osaka 8-17, Sanryo Material Co., Ltd. Osaka Branch

Claims (4)

[Claims] 1. A method for reusing the excavated residual soil by improving the soil quality of the excavated residual soil by adding and mixing a soil improving agent to the excavated residual soil having a high water content obtained in civil engineering construction work and then curing the mixture. Addition and mixing process of soil improvement material is (a)
Excavation surplus characterized by a combination of a setting accelerator adding and mixing step, (b) water absorbing polymer adding and mixing step, (c) quicklime addition and mixing step, and (d) cement-based hardening agent addition and mixing step. How to reuse. 2. The step of adding and mixing the soil-improving agent includes (a) adding and mixing step of setting accelerator, (b) adding and mixing step of water-absorbing polymer, (c) adding and mixing step of quicklime, and (d) cement-based material. The method for reusing excavated soil according to claim 1, wherein the steps of adding and mixing a hardening agent are performed in order. 3. A combination of an addition mixing step of (a) a mixture of a setting accelerator and a water-absorbing polymer, and (b) an addition mixing step of (b) quicklime and a cement hardening agent. A method for reusing excavated soil, comprising: 4. The method for recycling excavated soil according to claim 1, wherein the setting accelerator is water glass.