JPH0673729A - Execution method of built-in pile consolidating section - Google Patents

Abstract

PURPOSE:To reduce bleeding and a laitance so that the outflow of an impregnating material is not generated even in a ground having the large flow rate of river-bed water, and to prevent the separation of the moisture of the impregnating material by mixing a cement group hardener and the impregnating material, in which an underwater inseparable admixture is added into water, with the ground of a consolidating section. CONSTITUTION:A cement group hardener and an impregnating material, in which an underwater inseparable admixture displaying viscosity by the alkalinity of the cement group hardener is added into water, are mixed with soil and agitated while being discharged to a bearing ground 2 in the periphery of the lower end section of a pile body 1 at low pressure from the front end of an impregnating rod 3 with an agitating blade. These hardener and impregnating material are impregnated and mixed, and a bulbous solidified body 4 larger than a pile diameter is formed at the lower end section of the pile body, thus ensuring bearing power. Accordingly, a uniform consolidating section can be formed easily without requiring severe construction management.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for constructing a root-consolidated portion of a buried pile, and more particularly to a bulb-shaped solidified body having a diameter larger than the pile diameter obtained by mixing an injection material made of a cement-based hardening material with the ground at the lower end of the pile body. The present invention relates to a method of constructing an embedded pile root-fixing part that forms a bearing to secure bearing capacity.

[0002]

2. Description of the Related Art The embedded pile method is known as a type of construction method for driving ready-made piles to form a pile foundation. This method is to install a ready-made pile while excavating the ground at the tip of the pile by inserting an excavating tool into the hole drilled in the ground or in the hollow part of the pile by the pre-boring method, the middle excavation method, the jet method, etc. is there. Then, in this construction method, in order to secure a supporting force, after the pile is installed up to a predetermined support ground, a final impact construction method of impacting with a Monken or a hydraulic hammer and a root consolidation method of injecting and solidifying the injected material into the lower end of the pile Either one is adopted, but the root consolidation method is compared to the final impact method,
It has an advantage that it can be constructed with low noise and low vibration.

However, in the consolidation method, when the ground is drilled, loosening occurs in the periphery of the pile and the ground at the tip, and the supporting force is reduced. Therefore, as shown in FIG. For example, a method of vertically moving the injection material onto the surrounding support ground 2 while jetting it from the tip of the injection rod 3 under high pressure, a method of mixing and stirring with the soil while discharging at low pressure from the tip of the injection rod with stirring blades, etc. Inject and mix by
A method of forming a bulb-shaped solidified body 4 larger than the pile diameter at the lower end of the pile body to secure a supporting force is mainly adopted. In order to apply such a method, the injected material should be sufficiently distributed within the range considered at the time of design, and the fluctuation of the strength of the solidified body should be small, and the integration of the pile body and the root consolidation part and the tip blockage of the pile body should not occur. It is necessary to ensure that it is performed properly and that the injected material does not flow out due to underground water.

[0004]

However, the conventional method of mixing and injecting an injecting material has the following drawbacks.

That is, when the flow velocity of the underflow water of the ground to be constructed is high, there is a problem that the injecting material flows out and it is not possible to construct a rooting portion of a predetermined quality. In addition, since the water-to-cement ratio of the injection material is usually large, there is a large amount of breathing and latance, so it is difficult to ensure the integration of the pile body and the root consolidation part, and the water content of the injection material separates and becomes uniform. There has been a problem that the rooted portion cannot be formed. Although there has been an example in which a method of adding bentonite has been conventionally adopted as a method of compensating for such a defect, there is a problem that the strength of the root consolidation portion is greatly reduced when the amount of bentonite added is large.

Further, since the rooting portion is constructed at a deep position in the ground, its quality cannot be confirmed. Therefore, the stirring blade is rotated, the rod is vertically moved, the injection amount of the injection material and the injection pressure are increased. However, the quality of the rooted part must be assumed from the condition of construction management regarding the timing of injection, etc., but with conventional injection materials, the quality easily fluctuates depending on the condition of these construction management, so the quality is sufficiently secured. There was a problem that I was always worried about whether or not I was there.

Therefore, the present invention has been made to solve the above-mentioned problems, and does not cause the outflow of the injecting material even in the ground where the flow velocity of the underground water is large, and reduces breathing and leitance and injects the material. A method for constructing a root-consolidated portion of a buried pile that prevents the separation of water in the material to form a uniform root-consolidated portion, has less fluctuation in quality than before, and does not cause strength reduction due to the addition of a large amount of bentonite. The purpose is to provide.

[0008]

The present invention has been made in view of the above objects, and its gist is a root for securing a supporting force at a lower end portion of a pile body driven into the ground by an embedded pile method. In the method of constructing a solidified portion, there is provided a method of constructing a solidified portion of a buried pile, which is characterized by mixing a cement-based hardening material and an injectable material obtained by adding an underwater non-separable admixture to water, and mixing it with the ground of the solidified portion.

Here, the cement-based hardening material means a powder material which is hardened by a hydration reaction with water, for example, Portland cement, hydraulic lime, plain cement such as natural cement, blast furnace cement, silica cement, fly. Examples include mixed cement such as ash cement, special cement such as alumina cement, and super rapid hardening cement.

Further, the cement-based hardening material and the inseparable underwater admixture added to water exhibit viscosity due to the alkalinity of the cement-based hardening material, and include, for example, polyvinyl alcohol, polyethylene oxide, carboxymethyl cellulose, Polymeric substances such as methyl cellulose, hydroxymethyl cellulose and polyacrylamide can be used.

Further, the addition amount of the water-immiscible admixture is preferably 0.3 to 1.2% by weight with respect to water. If the added amount exceeds 1.2%, the viscosity becomes excessive,
If it is less than 0.3%, the thickening effect is small, and thus both are not preferable.

In addition, in the method for constructing the embedded pile root consolidation portion of the present invention, an inseparable admixture in water and an AE water reducing agent are added to the cement-based hardening material and water as an injecting agent to be mixed with the ground of the soil consolidation section. It is also possible to use the prepared one.

Here, A added to the cement milk
The E water-reducing agent enhances the dispersibility of the cement-based hardening material and improves the fluidity of the injection material, and for example, a lignin sulfonate, a lignin polyol complex or the like can be used.

The amount of the AE water reducing agent added is preferably 2.0 to 3.0% by weight with respect to the cement type hardener.

[0015]

According to the method for constructing the embedded pile root-hardening portion of the present invention, the cement-based hardening material and the water-separable admixture added to water react with the alkalinity of the cement-based hardening material and become viscous in the injection material. Is given. In addition, the pouring material is given a viscosity so that it does not flow out even in the ground where the flow velocity of underground water is large, and it prevents the occurrence of breathing and leitance and the separation of the water content of the pouring material for uniform consolidation. It is possible to form a part.

If an AE water reducing agent is further added to the injecting material obtained by adding an inseparable admixture in water to cement milk, the AE water reducing agent enhances the dispersibility of the cement-based hardening material and causes the flow of the injecting material. Improve sex.

[0017]

[Example] In the ground where there is underground water near the support layer, a steel pipe pile with a diameter of about 1000 mm is driven to a predetermined depth by the intermediate excavation method, and then water is added to ordinary Portland cement to stir it and further it is inseparable from water. The injection material to which the admixture and the AE water reducing agent were added was pressure-fed, and the injection material was injected while stirring the tip ground with a stirring blade to construct a root-hardening part.
In this example, the construction was carried out without strict control of the injection material injection timing and the like. Also, in order to directly confirm the solidification property of the root consolidation part,
Core boring was performed from the hollow portion of the pile, and the core was sampled from three depths above, below, and below the root consolidation portion, and a uniaxial compression test was performed.

The formulations of the casting materials used are shown in Table 1 as Examples A and B. In addition, Example A is based on a basic composition, and Example B has a water-cement ratio of 45%.
An example of the composition when the amount is reduced to 10 is shown.

Further, the composition of the conventional injection material containing no water inseparable admixture and no AE water reducing agent is shown in Table 1 as Comparative Example 1.
Shown in.

[0020]

[Table 1] Further, Table 2 shows the test results of the uniaxial compression test performed on the samples of the upper, middle, and lower three depths, which were collected from the root consolidation portion of the piles constructed by using the injection material of Example A and Comparative Example 1. .

[0021]

[Table 2] From these results, it was found that the method for constructing a rooted portion according to the present invention allows a rooted portion of a predetermined quality to be easily constructed by normal management without requiring strict construction management as in the past.

Further, a test pile was constructed with the composition of Example A, and after forming a root consolidation portion near the surface of the ground, the root consolidation portion was dug out to investigate the solidification property. As a result of this investigation, it was found that the method for constructing a rooted portion according to the present invention can provide a rooted portion that is uniform and of high quality with less occurrence of breathing and laitance.

[0023]

Industrial Applicability As described above, the method for constructing the embedded pile root consolidation portion of the present invention is based on the cement-based hardening material and the injection material obtained by adding the water inseparable admixture to water. Since it mixes with the groundwater, even if the groundwater has a large flow velocity of the underground water, the outflow of the injection material does not occur, and breathing and latance are reduced and the water content of the injection material is prevented from being separated to form a uniform solidified portion. Can be easily formed,
In addition, the construction can be easily performed without requiring the strict construction management as in the past.

[0024] If the AE water reducing agent is further added to the injection material, the dispersibility of the cement-based hardening material is increased and the fluidity of the injection material is improved, so that a more uniform root consolidation portion is formed. Can be formed.

[Brief description of drawings]

FIG. 1 is an explanatory view showing an outline of an embedded pile construction method to which a method for constructing an embedded pile root consolidation portion of the present invention is applied.

[Explanation of symbols]

 1 Pile body 2 Support ground 3 Injection rod 4 Solidified body

Claims (2)

[Claims] 1. A method for constructing a root-hardening portion for securing a supporting force at a lower end portion of a pile body driven into the ground by an embedded pile method, wherein a cement-based hardening material and water are used as an inseparable admixture. A method for constructing an embedded pile root consolidation part, characterized in that the added injection material is mixed with the ground of the root consolidation part. 2. The embedded pile root consolidation according to claim 1, characterized in that a cement-based hardening material and water to which an underwater non-separable admixture and an AE water reducing agent are added are used as the injecting material. Part construction method.