JP2704839B2 - Pile foundation method for soft ground reinforcement - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for strengthening a foundation ground carried out in the field of civil engineering and construction, and more particularly, to a hydraulically hardened soil stabilizing material in a pit formed from the ground surface of a soft ground having a high water content. The purpose of this method is to improve the construction method of forming pile foundations by charging and filling with water and hardening by infiltration of soil moisture.

[0002]

2. Description of the Related Art Conventionally, as one method of strengthening soft ground having a large water content, there is a quicklime pile foundation method, in which quicklime introduced into a pit absorbs moisture in the soil and causes digestive heat. The effect of expansion and hardening is to lower the water content of the ground and increase the soil density around the pile by the consolidation effect of about twice the volume expansion, thereby improving the supportability of the ground. When the digestive heat generated by the digestion is rapidly performed, the steam generated is likely to cause a bumping accident, and the formed slaked lime pile requires a long period of several months or more to obtain sufficient strength. As an improvement, a method of using a mixture of quicklime and Portland cement as main components and a small amount of aluminum powder mixed therewith has been implemented (for example, Japanese Patent Publication No. Sho 64-64).
No. 1516). On the other hand, as a pile foundation construction method by casting in place on soft ground with a large moisture content, a method of reducing the weight of the pile itself by using foamed polystyrene particles in a cement soil slurry to prevent settlement is used. It has been proposed (for example,
The 28th Geotechnical Engineering Research Presentation 1009, Iwao et al.
reference).

[0003]

In the above-mentioned known pile foundation method, in the former method using a mixture of quicklime, Portland cement and aluminum powder, slaked lime and Portland cement as main materials are made equal in volume. There is a danger of bumping accidents in the ground where the water content is large where the water absorption is rapid, and the hydrogen gas generated by the alkali component of the added aluminum powder escapes to the outside before the pile hardens. The effect of reducing the pile weight was small. Further, the latter method using a cement soil slurry containing expanded polystyrene particles is effective in reducing the weight of the pile, but the density and strength of the pile are likely to be non-uniform due to the floating separation of the expanded polystyrene particles having a light specific gravity, and There were drawbacks such as the effect of soil improvement on the pile periphery could not be expected.

[0004]

SUMMARY OF THE INVENTION The present invention addresses the drawbacks of the conventional cast-in-place foundation pile method in the case of using lime, portland cement, and a soil stabilizing reinforcing material mixed with aluminum powder to reduce the proportion of lime to portland cement. The problem was solved by blending the inorganic filler and the foamable thermoplastic synthetic resin raw material, and the disadvantage of the heterogeneous curing of the conventional method of blending the expanded polystyrene particles was also attributable to the foamable thermoplastic synthetic resin raw material. This problem has been solved by using particles to effectively utilize the foaming / expansion effect due to heat generated during casting.

That is, according to the present invention, an expansion-hardening soil stabilizing material, which is a mixture having the following composition, is charged and filled into a vertical hole provided on a soft ground, and a hardened pile is generated with heat generation and expansion due to the penetration of water in the soil. This is a foundation method for soft ground reinforced pile, characterized by forming Soil stabilizing agent composition Portland cement 40-60% by weight Quick lime 15-35 無機 Inorganic filler 10-30 原 Foaming thermoplastic synthetic resin raw material 1-6 〃 (Hollow particles whose volume is 20 times or more by steam at 80 ° C.) Which becomes

[0006] The soil stability reinforcing material used in the present invention has the above-mentioned composition, so that the hardening reaction proceeds quickly and smoothly in accordance with the permeation and water content of the soil moisture, and the heat of digestion of quicklime having a lower blending amount than Portland cement is inorganic. The mixture gradually progresses due to the blending of the filler, and the quicklime becomes slaked lime with approximately twice the volume, and steam is also gradually generated. The weight of the cured product is increased by increasing the volume while exerting an inflation pressure on the periphery to increase the volume of the cured product.
It is determined experimentally as satisfying conditions such as density.

[0007]

In the composition condition of the soil stability reinforcing material, quicklime becomes a hydraulic binder together with Portland cement, but the strength of the hardened material tends to decrease as the quicklime ratio increases, while the volume expansion property and Water absorption and digestive calorific value are increased, the inorganic filler is capable of adjusting the above-mentioned action to obtain a stable cured pile, and the foamable thermoplastic synthetic resin raw particles are usually Particles having a diameter of 1 to 2 mm, such as polystyrene, styrene-maleic anhydride copolymer, and styrene-ethylene mixture containing 5 to 7% of a hydrocarbon-based blowing agent;
A foam that reaches 20 to 80 times under normal pressure by steam heating at a temperature of ℃ or more. Therefore, during the hardening process of the soil stability reinforcing material, it expands while exerting pressure on other volume components and hardened pile. However, when the content is 6% by weight or more, a decrease in pile strength is recognized.

[0008]

EXAMPLES The results of the following test methods will be described below as examples. (1) Test conditions 5c of sandy soil in a test tank with an inner diameter of 50x50x50cm
After filling to a thickness of m, a pipe having an inner diameter of 16 cm and a length of 25 cm made of a tin plate having a thickness of 0.2 mm is erected, and the outer periphery thereof is further filled with sandy soil of 25 cm. The soil stabilizing reinforcement, which is a mixture of powder and granules of the composition, is filled up to a height of 20 cm, and the sandy soil is further filled thereon with 5c.
After filling, the pipe was pulled out, and then 3 to 5 liters of water was sprayed and supplied to the sandy soil surface under a state in which a load composed of an iron plate having a diameter of 20 cm, a thickness of 2 cm, and a weight of about 5 kg was placed on the upper surface thereof. Thus, a cured sample obtained by curing for 28 days was obtained. The dimensional change, density and uniaxial compressive strength of the cured sample were measured.

[0009]

[0010] FIG. 1 is a graph of the compressive strength shown together with the 14-day curing data.

In the above test, the comparative example is a quick lime / cement type anti-bumping soil stabilizing material that is currently in practical use. Excellent, which makes it possible to compact the soil around the pile periphery and to significantly reduce the weight of the cured pile.

[0012] Although the soil stability reinforcing material in the previous example was used as a powder mixture of the composition components, the use of the mixture as a pressed granule having an average particle size of 3 to 5 cm allowed the input work to be carried out. In addition to the prevention of dust particles, it is possible to maintain a uniform composition of the cured product.

[0013]

As described above, the pile foundation method according to the present invention is effective in absorbing the soil moisture of the soil stabilizing reinforcing material in the soft ground having a high water content, and reducing the weight of the casting pile by the expansion heat setting. The soil strength can be improved and the pile density can be easily formed even on ultra soft ground with a water content of 150% or more and a soil density of 1.3 or less. is there.

[Brief description of the drawings]

FIG. 1 is a graph showing a measured density of a uniaxial compressive strength of a soil stability reinforcing material according to an embodiment of the present invention at 14 days and 28 days of curing and a wet density at 28 days of curing.

Continued on the front page (51) Int.Cl. ⁶ Identification number Agency reference number FI Technical display location E02D 3/08 E02D 3/08 3/12 3/12 5/46 5/46 // C09K 103: 00

Claims (3)

(57) [Claims] 1. An expansion-curable soil stabilizing material, which is a mixture having the following composition, is charged and filled into a vertical hole provided on a soft ground, and a hardened pile is generated with heat generation and expansion due to water absorption and permeation of soil moisture. A soft ground reinforced pile foundation method characterized by forming. Soil stabilizing reinforcement composition Portland cement 40-60% by weight Quick lime 15-35 〃 Inorganic filler 10-30 発 泡 Foamable thermoplastic synthetic resin granules 1-6 〃 (Hollow particles whose volume is 20 times or more by steam at 80 ° C.) Which becomes 2. The soft ground reinforcement pile foundation method according to claim 1, wherein the inorganic filler in the soil stability reinforcement is calcium carbonate or zeolite or both. 3. The method according to claim 1, wherein the soil stability reinforcing material is a pressed granulated material having an average particle size of 3 to 5 cm.