JPH0280709A - Preparing water permeable structural soil - Google Patents

Abstract

PURPOSE:To make water permeability and compressive strength compatible by a method wherein a soil, having a specific range of soil texture, is mixed with a hydraulic material, and an organic acid solution with weak acidity is added thereto so that the moisture content of the mixed soil becomes a fixed multiple of the optimum moisture content for compaction, and compaction is applied thereon. CONSTITUTION:The method is such that a soil, for example, having soil texture within the range from SL to LS in the classification by the International Pedological Society is mixed with a hydraulic material such as cement. Then adjustment is made by sprinkling thereon a mixture made of citric acid solution and ethylene acid emulsion, so that the moisture content of the mixed soil becomes 1.2 to 1.5 times the optimum moisture content for compaction. After applying agitation, the mixed soil is spread and levelled, and compaction is applied thereon. After completion of the compaction, the mixed soil is kept under sheet curing for a duration of 1 to 21 days and water is sprinkled thereon in the quantity of 1 to 2l/m<2> during that period. Thereby permeability and the expected compressive strength can be obtained.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention provides construction soil that has water permeability as construction soil, does not freeze up, has compressive strength and bending strength, and has water permeability that is suitable for various uses. This invention relates to a soil construction method.

(Prior Art) As a construction method for construction soil, the economical soil cement method is generally used.

This soil-cement method has a variety of uses, including rigid and deflecting roads, streets, lower and upper bases for airports, surface treatment of slopes subject to periodic and continuous water inundation and wave action, etc. The main products are cores for earth dams and linings for reservoirs.

The conventional soil cement method has been applied to the above-mentioned sites, but until now it has been used carefully, using an extremely large amount of cement, and concentrating water to achieve the optimal soil moisture content ratio for soil compaction. The main focus was to obtain compressive strength and bending strength through mechanical compaction and curing.

Therefore, the construction soil obtained by the soil cement method is naturally non-permeable, and since it is applied to sites where it must be impermeable, the soil cement method, which has permeability, has not been considered until now. That never happened.

On the other hand, the weakening of the ground surface caused by rainwater at various sports stadiums, sidewalks, jogging courses, etc., has become a problem as it limits the time and period of use.

In addition, a lower base course for sports stadiums constructed using artificial grass or artificial grass filled with dry sand has recently been considered.

Therefore, the inventors of the present invention have made various attempts to apply the soil cement construction method to the above-mentioned sports surf ace, the lower roadbed of artificial grass, sidewalks, jogging courses, etc.

However, it has been found that the soil cement method has a fatal drawback when used for the above-mentioned purposes. Since it is originally impermeable, it has very poor permeability, secondly, it suffers from frost heave in areas where the temperature drops below freezing, and furthermore, the soil surface is destroyed by the cold.

The characteristics of soil cement are that when trying to increase water permeability,
There is a contradictory relationship between the compressive strength decreasing and the water permeability decreasing when trying to increase the compressive strength, and it is a very difficult problem to solve the above disadvantages. It is also required to have water permeability and compressive strength to the extent that it has appropriate bounce and cushioning properties, and in that sense it is the most difficult sports surf ace.

Therefore, one of the inventors of the present invention proposed several methods for constructing these water-permeable construction soils, and achieved considerable results through testing.

However, these methods also have problems as described below.

(Problem to be solved by the invention) The important point when applying soil cement is to form a uniform layer with the desired strength by compacting the entire surface in a short time at the optimum soil moisture content. It's about doing.

However, in the conventional construction soil construction method, soil, hydraulic materials (cement, etc.), and water are mixed, leveled, and then compacted, but this poses a problem if the construction soil is small. However, if there is a large amount, it will take time to level the ground, level the ground, etc., and compaction will have to be done 5 to 6 hours after mixing water and hydraulic material, resulting in problems such as not being able to obtain the original strength. occurs.

For this reason, a method has been used to delay the coagulation reaction between water and hydraulic materials by mixing a water reduction retardant, but commercially available water reduction retardants are very expensive; However, even if it was mixed in, it was not possible to delay the coagulation reaction and obtain the desired strength.

As mentioned above, the soil cement construction method had many problems, especially during construction, but the great appeal of soil cement construction soil is that it is inexpensive, and the inventors of the present invention dared to do so. We have been working on solving the above problems and have conducted repeated research.

We have now obtained new knowledge through research and experiments, and have completed the present invention based on this new knowledge.

(Means for solving problems) The structure of the present invention will be explained in detail by referring to examples.

First, the construction method of the present invention will be explained. The soil used in the construction method of the present invention has a soil quality in the range of SL to LS according to the coordinates of the International Society of Soil Science.

Soil in this range has properties that allow it to be easily mixed with hydraulic materials and to increase its compressive strength when compacted.

However, if the soil contains 5% or more of soil particles with a size of 105μ or less, as a pretreatment, the soil and hydraulic material are mixed and coagulated to bring the soil texture to a range of SL to LS. Adjust particle size and use in soil.

To explain an example of this case, the moisture content of soil with a soil texture of CL-L is set between 15 and 40%, and cement is set between 30% and 40%.
If you mix it with 50kg and leave it for a day and night, the soil quality will be SL.
Particle size can be adjusted to soil around the range of ~LS.

In addition, the hydraulic material in the present invention refers to materials that harden with water, such as gypsum and lime in addition to cement, and the organic acid aqueous solution exhibiting weak acidity refers to an aqueous solution of citric acid, tartaric acid, oxalic acid, etc. It is.

In addition, synthetic resin emulsions include ethylene acetate emulsions, acrylic emulsions, acetic acid emulsions, latex, etc., and polymeric soil aggregation agents include polyethylene oxide, polyacrylamide, polyolefin, and polyvinyl acetate. That's true.

(Example) The optimum soil water content ratio for compacting soil whose soil texture is in the range of SL to LS is approximately 6 to 15% on the LS side and approximately 15 to 25% on the SL side.
%.

Soil compaction Optimal soil moisture content of 14.5% soil In-?
18. In contrast, 100 kg of cement is mixed and the soil water content ratio is 1.27 times the optimum soil water content ratio for soil compaction.
Adjust the soil moisture content by sprinkling a mixture of 100 g of citric acid in 54.312 water and 15 kg of ethylene acetate emulsion to obtain a soil moisture content of 4%. After 6 hours of leveling the ground, it was pressed 3 to 4 times with a 4t roller.

In that case, the hydraulic conductivity is 4 x 10-'cm/s e
It was c.

What is important in this case is that if the hydraulic material and soil are compacted at the optimal soil water content ratio for soil tamping, it will not have compressive strength but will have water permeability. When compacted below, water permeability is good, but
This means that the compressive strength is significantly reduced.

Furthermore, when soil is compacted at a soil water content ratio that is 1.5 times or more than the optimum soil water content ratio, both water permeability and compressive strength decrease.

Therefore, by compacting the soil at a soil water content ratio that is 1.2 to 1.5 times the optimal soil water content ratio, it is possible to obtain a satisfactory compressive strength while maintaining good water permeability.

Next, in order to increase the bending strength of the soil surface and prevent soil surface destruction due to cold, the sheet should be cured for 1 to 21 days, preferably 1 to 5 days after completion of compaction. 2I
When watering at a rate of 2/rn', the bending strength of the soil surface is 28
Compared to the 2.1 kg/crn'' in the area without watering under the daily timber law, we were able to significantly increase the water consumption to 2.7 kg/crn''.

In addition, if water is sprinkled within 1 to 5 days after completion of compaction, the soil and cement may not be strongly solidified.
．． Sprinkling 03% aqueous solution will not generate muddy water, so
The effect is more pronounced.

Next, to explain how to prevent frost heaving, soil is said to have a frost heaving inhibiting effect if its compressive strength is 20 kg/crd or more.

To increase the strength to this level, apply 1.5 to 2 I2/
It is sufficient to sprinkle water at a rate of about cr rn', and the water permeability will not change if this is done, but the compressive strength is 22.0 kg at 28 days old.
/crn'.

Therefore, the soil water content ratio is 1 of the optimum soil water content ratio for soil compaction.
．． Despite being compacted 6 hours after adding a weakly acidic organic acid aqueous solution to 2 to 1.5 times the volume and stirring, the soil surface remained permeable and did not freeze up due to cold weather. It was possible to make the construction soil without destruction.

By the way, the soil water content ratio should be set at 1.2 to the optimum soil water content ratio.
The compressive strength of 1.5 times the volume of water added and compacted 6 hours after stirring was 10 kg/cm'' at 28 days' age.・Even when Nippon Sika Co., Ltd.) was added, the yield was 14 kg/c rrI2 at 28 days old.

Next, we will explain how to construct the lower base course for tennis clay courts and artificial grass sports stadiums at the site. First, it is decided whether to build up the floor or dig the floor at the site, and both the leveling and the digging are done to a depth of about 30 cm. To explain the site of the inner bed filling, 0 to 40 mm of crushed stone or sandy soil is laid down to a thickness of 15 cm on the local roadbed and compacted with rollers.

Next, either bring good quality soil with a soil quality in the range of SL to LS to the site, or if using it on site, check to see if it contains 5% or more of soil particles of 105 μ or less, and check if the soil contains 5% or more. If so, adjust the particle size with cement.

The above soil is spread about 15 cm on top of crushed stones, etc., and cement is sprinkled at 100 kg/rrl, and the soil and cement are mixed using a tractor or the like.

The soil moisture content of this mixed soil was investigated, and an aqueous solution of 54°312 citric acid and ethylene acetate were added to 1rr1' of soil so that the soil moisture content was 1.2 to 1.5 times the optimal soil moisture content for soil compaction. Sprinkle water with a mixture of 15 kg of emulsion and stir the soil again with a tractor. After this, 4
Temporarily roll and roll 2 to 3 times with a T roller, then correct unevenness,
Next, perform the main compaction and complete. Once completed, in order to increase the bending strength of the soil surface, spread a 0.04% aqueous solution of polyethylene oxide at least once (1-2β/rr1") while curing the soil for 1-5 days. In order to increase the compressive strength between 7 and 21 days after completion, steps 1.5-b were completed once or twice.

(Function) Test construction was carried out on the applicant's grounds in early November 1985, with no outsiders allowed to enter, and when the wintering conditions were investigated in mid-February 1988, there was no frost heaving ( The compressive strength is 22.5 kg/cm', the bending strength is 3.1 kg/crn'', and the permeability coefficient is 4 X l
O-'cm/sec showed almost the same value as the 28th day of wood age.

The general clay court built at the same ground had been completely frozen over and had become so soft that it could not be used due to rainwater.

(Effects of the Invention) As explained above, the soil cement constructed by the method for constructing constructed soil with water permeability according to the present invention is made by adding an organic acid aqueous solution exhibiting weak acidity to increase the soil water content ratio to the soil's peak. The soil moisture content is adjusted to 1.2 to 1.5 times the optimum soil moisture content.
Even if there is a large amount of construction soil and it takes a long time to tamp the soil, adjust it to 1.2 to 1.5 times the optimum soil water content, level it, level the ground, etc. The compressive strength is obtained.

Therefore, the optimum soil moisture content for soil tamping is 1°2 to 1.
Even if the soil cement is simply adjusted to 5 times the moisture content, or the soil cement is adjusted to 1.2 to 1.5 times the optimal soil moisture content for soil tamping by mixing an expensive commercially available water reduction retardant, the adjustment is not possible. Although it was not possible to obtain the initial desired compressive strength after a long period of time, such construction problems have been resolved.

Also, within 1 to 21 days after the completion of compaction, a small amount (both 1
Times 1-21! ,/rd watering, the soil surface has bending strength and water permeability.

Furthermore, even if the soil contains 5% or more of soil particles with a size of 105μ or less, as a pretreatment, the soil and hydraulic material are mixed and coagulated to bring the soil texture to a range of SL to LS. Since the particle size is adjusted before use, there are no restrictions on the soil that can be used.

Therefore, although water permeability was never considered in conventional soil cement construction methods, the construction soil construction method of the present invention not only has water permeability, but also has compressive strength and bending strength, and is ideal in that it does not have frost heave. The construction soil of the present invention can be applied to various sports stadiums such as Surf Ace, which is said to be the most difficult among them, because it is economical as well as the soil cement construction method. clay courts, sidewalks, jogging courses,
Alternatively, if it is used for the sub-base course of an artificial turf sports stadium, it is ideal because it has compressive strength but is permeable and has good drainage (and will not freeze up even in sub-zero temperatures). Because there is no surface damage due to cold weather, it has special effects, such as being able to be used in applications that could not be applied with conventional soil cement construction methods.

Claims (1)

[Claims] 1) When constructing the construction soil, mix the soil with the soil texture in the range of SL to LS and hydraulic material, and adjust the soil water content to 1.0 to 1.0, the optimum soil water content for compacting the soil. 1. A construction method for construction soil having water permeability, which comprises adding an aqueous solution of a weakly acidic organic acid to a concentration of 2 to 1.5 times, stirring, and then rolling the soil. 2) When constructing the construction soil, mix the soil with a soil texture in the range of SL to LS with a hydraulic material, and adjust the soil water content ratio to 1.2 to 1.5 times the optimal soil water content ratio for compacting the soil. A method for constructing constructed soil with water permeability, which comprises adding an organic acid aqueous solution exhibiting weak acidity, stirring and rolling, and then sprinkling water on the rolled surface at least once within 1 to 21 days. . 3) As a pretreatment, soil with a water content of 10 to 40% and containing 5% or more of soil particles of 105μ or less is mixed with a hydraulic material to adjust the particle size to a range of SL to LS, and An aqueous solution of a weakly acidic organic acid aqueous solution and a synthetic resin emulsion by mixing the diameter-adjusted soil and a hydraulic material and tamping the soil moisture content to 1.2 to 1.5 times the optimum soil moisture content. is added, stirred and compacted, and an aqueous solution of a soil agglomerating agent is sprinkled at least once within 1 to 5 days after completion of compaction, and further watered at least once during 7 to 21 days after completion of compaction. A construction method for construction soil having water permeability, characterized by: