JP3572567B2 - Pile construction method - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a pile construction method in which a pile is driven in a ground where a water-permeable layer ground exists above and below an impermeable layer ground, and the upper water-permeable layer ground contains contaminated groundwater. .
[0002]
[Prior art]
In the middle layer, which contains an impermeable ground consisting of a clay layer or silt layer, and a water layer containing a sand layer and a gravel layer above and below it, the water layer is an aquifer. Often have groundwater. Such groundwater has important uses as industrial water and domestic water. However, due to recent industrial activities, harmful pollutants are frequently mixed into the groundwater. In such a situation, the permeable ground exists above and below the permeable ground, and in the ground where the upper permeable ground contains contaminated groundwater, the lower permeable ground penetrates the permeable ground. When laying piles that reach the height, the contaminated groundwater contained in the upper permeable ground flows into the lower permeable ground through the gap around the piles during or after construction, The clean groundwater inside was also to be contaminated.
[0003]
[Problems to be solved by the invention]
However, conventionally, in such a ground, there has been no method of placing a pile that can effectively prevent the contamination of the groundwater contained in the lower permeable ground. As a result, not only could effective use of groundwater be prevented, but also the natural environment would be adversely affected. In particular, there has been a serious problem when toxic substances such as cadmium compounds and cyanide compounds are mixed in the contaminated groundwater.
The present invention has been made in order to eliminate the above-described drawbacks. In the case where the permeable ground exists above and below the permeable ground and the upper permeable ground contains contaminated groundwater, the present invention has been made. When placing piles that penetrate through the permeable ground and reach the lower permeable ground, check that the contaminated groundwater in the upper permeable ground flows into the lower permeable ground during or after the pile installation. It is an object of the present invention to provide an effective pile construction method for preventing the pile.
[0004]
[Means for Solving the Problems]
In short, the present invention relates to a pile construction method in which a pile is placed on a ground having contaminated groundwater containing contaminants, where a water-permeable ground exists above and below the water-impermeable stratum. ) Installation process of extracorporeal pipe in the upper permeable ground in pile construction area, (b) excavation and cleaning process inside the extracorporeal pipe, (c) pile setting process inside the extracorporeal pipe, (d) pile construction area A stabilizing material having a property of directly reacting with the contaminant to form an insoluble substance, and a filling material for preventing the infiltration of the contaminant into a central part ; A material filling step of filling a filling material containing at least one of a decomposition material having a property of decomposing a substance to make it harmless and an adsorbent material capable of adsorbing the contaminant between the extracorporeal tube and the pile; To include each process of It is to provide a pile construction method for the butterflies.
[0005]
That is, the present invention prevents the infiltration of contaminated groundwater into the pile construction area and prevents the penetration of contaminants into the lower permeable ground at the time of pile driving by installing an extrapolation pipe. In addition, by filling the space between the extrapolation pipe and the cast pile with the filling material, it is possible to prevent infiltration of the contaminant into the center of the pile construction area after the pile is placed, and to be included in the lower permeable ground. It prevents contamination of clean groundwater.
[0006]
BEST MODE FOR CARRYING OUT THE INVENTION
An example of an embodiment of a pile construction method according to the present invention will be described in detail with reference to the accompanying drawings.
As shown in FIGS. 1 and 2, the target ground to which the present method is applied includes an impermeable layer ground 2, 2 ′ composed of a clay layer and a silt layer in the middle layer, and sand layers and gravel above and below it. It is a ground having a permeable ground 1, 1 ', 3, 3' including a layer. In the following embodiment, a construction method on such a ground is shown. The same method can be applied to the ground and the like where the grounds are alternately present.
[0007]
The pile construction method according to the present invention includes four essential steps: (1) an extrapolation pipe installation step, (2) an excavation and cleaning step inside the extrapolation pipe, (3) a pile setting step, and (4) a material filling step. As an optional step, (5) a step of pulling out the extracorporeal tube may be performed after the material filling step which is the fourth step. Hereinafter, the content of each step in the first embodiment and the second embodiment will be described.
[0008]
First Embodiment A first embodiment will be described with reference to FIG.
First, a description will be given of a first step of installing the extracorporeal tube 10 on the upper permeable ground 1 in the pile construction area 4. As shown in FIG. 1 (a), in this step, the extracorporeal pipe 10 is laid from the upper permeable ground 1 to the predetermined depth of the impermeable ground 2 at the outer periphery of the pile construction area 4. This is a step of installing the extracorporeal tube 10. By this process, at the time of pile construction, the water barrier inside the pile construction area 4 is ensured, and it is possible to prevent contaminants existing in the contaminated groundwater of the upper permeable ground 1 from entering the inside of the extracorporeal tube 10. it can.
In addition, the method of installing the extracorporeal tube 10 can be performed by a method similar to a conventionally performed method. For example, using an impact or vibration method, the extracorporeal pipe 10 is made to penetrate the upper permeable ground 1 in the pile construction area 4. The outer tube 10 is generally made of a steel material, but may be made of another material, and the shape and the like are not particularly limited. Furthermore, there is no particular limitation on the depth of the intubation of the intubation 10, and it can be determined according to the ground conditions.
[0009]
Next, a second step, that is, a step of excavating and cleaning the inside of the extratubular tube 10 will be described. As shown in FIG. 1B, this step is a step of excavating earth and sand inside the extracorporeal tube 10 installed in the first step and cleaning the inside thereof. This is a step performed to secure the space 11.
The excavation and cleaning steps inside the extracorporeal tube 10 can be performed by the same method as that conventionally performed. In the excavation step, for example, a method of excavating using various excavators can be used. In the cleaning step, a method of cleaning the inside of the extracorporeal tube 10 using a water jet or the like after the excavation step is completed. It can be used.
The shape, size, etc., of the inside of the outer tube 10 are not particularly limited, and can be determined according to ground conditions. If a problem occurs in the stability of the excavated bottom, the stability of the excavated bottom is improved by injecting uncontaminated water into the extracorporeal tube 10 so as to be higher than the groundwater level of the upper permeable ground 1. It is possible to secure.
[0010]
Next, a third step, that is, a step of driving a pile into the outer tube 10 will be described.
In this step, as shown in FIGS. 1 (c) and 1 (d), the upper permeable ground 1 and the impervious ground 2 are penetrated into a pile driving space 11 provided inside the outer tube 10, This is a step of driving a pile K to reach a predetermined depth in the lower permeable ground 3. In this step, basically, any method can be used regardless of the method of placing the pile K. Therefore, various construction methods such as a hammering method, an embedded pile method, and a cast-in-place pile method can be adopted according to the ground conditions.
There is also no particular limitation on the material, shape, etc. of the pile K. Therefore, various piles such as steel piles, ready-made concrete piles, prestressed concrete piles, composite piles of steel and concrete, etc. can be constructed. Pillar foundations can also be constructed.
Furthermore, by providing a projection or the like on the pile K, it is possible to enhance the adhesion of the pile K.
[0011]
Next, the material filling step, which is the fourth step, will be described.
As shown in FIG. 1 (e), the present step is performed by a filling material M for preventing the intrusion of the contaminant into the center 4a of the pile construction area, that is, for example, a material that blocks the contaminant or the contaminant. Any one of the materials having reactivity and adsorption to the substance and preventing intrusion of the contaminant into the pile construction area center 4a, or a combination of any of the above materials In this step, the filling material M is filled in the filling portion 11a formed between the extracorporeal tube 10 and the pile K.
Specifically, the above-mentioned filling material M is filled into the pile K which is driven into the pile driving space 11 by the first to third steps and the filling portion 11a formed between the pile driving space 11. It is performed by inputting and compacting.
[0012]
Various materials can be used as the filling material M, and the material is not limited to the following materials. As a material for blocking pollutants, a water-impermeable material is a typical material. Typical materials that are reactive and adsorbent to contaminants and prevent intrusion of contaminants into the pile construction area center 4a include stabilizing materials, decomposition materials, and adsorbent materials. It is. Hereinafter, the properties of each filling material M will be described.
[0013]
The impermeable material is a substance having an effect of blocking contaminated groundwater flowing into the filling portion 11a after the impermeable material is hardened, and is made of mortar, concrete, or the like. In other words, the purpose of using the water-impermeable material is to fill the filling portion 11a with the above-described water-impermeable material so that the filling portion 11a serves as a water-impermeable ground to block ground water contaminated from the outside, and To prevent ingress of contaminants into the environment.
[0014]
The stabilizing material is a substance having a property of directly reacting with the contaminant to form an insoluble substance. In other words, the purpose of using the stabilizing material is to convert the contaminant dissolved in the contaminated groundwater into an insoluble material by the stabilizing material present in the filling portion 11a, thereby converting the contaminant from the contaminated groundwater. By separating and removing in the filling section 11a, contaminated groundwater flowing into the filling section 11a is finally rendered harmless, thereby preventing intrusion of contaminants into the pile construction area center 4a. .
However, since the stabilizing material that reacts to the contaminant differs depending on the type of the contaminant contained in the contaminated groundwater, a stabilizing material for replacing the stabilizing material according to the condition of the contaminated groundwater as described below is used. You need to decide.
[0015]
For example, when the contaminant is a hexavalent chromium compound, a reducing agent such as ferrous sulfate, sodium sulfite, or metabisulfite is suitable as a stabilizing material. This utilizes the property that hexavalent chromium compounds are easily soluble in water, but trivalent chromium compounds are hardly soluble. With this, it is changed into an insoluble substance of Cr (OH) ₃ or Cr ₂ (SO ₄ ) ₃ and removed from the contaminated groundwater.
[0016]
According to the same concept as when removing the hexavalent chromium compound, even when other pollutants are contained in the contaminated groundwater, by using the following stabilizers corresponding to each pollutant, Can be removed.
When the contaminant is a cadmium compound, a sodium compound or a mercury compound, sodium sulfide is suitable as a stabilizing material.
When the contaminant is a cyanide, sodium hypochlorite is suitable as a stabilizing material.
When the contaminant is an arsenic compound, iron chloride is suitable as a stabilizing material.
Furthermore, heavy metals such as hexavalent chromium, cadmium, lead, selenium, and arsenic can be removed by using metal powder such as iron powder as another stabilizing material.
[0017]
The decomposition material is a substance having a property of decomposing the contaminant and rendering it harmless by reacting with the contaminant. In other words, the purpose of using the decomposed material is to decompose the contaminant dissolved in the contaminated groundwater by the decomposed material existing in the filling part 11a, thereby finally contaminating the contaminated groundwater flowing into the filling part 11a. And to prevent intrusion of contaminants into the pile construction area central part 4a.
However, since the decomposed material that reacts with the contaminant varies depending on the type of the contaminant contained in the contaminated groundwater, it is necessary to determine the decomposed material to be replaced according to the status of the contaminated groundwater. For example, when an organic chlorine compound is contained as a pollutant, a predetermined effect can be obtained by adding iron powder as a decomposition material.
[0018]
The adsorptive material is a porous material capable of adsorbing the above contaminants with a very large adsorptive capacity, and includes activated carbon, coal ash, charcoal, lignite, zeolite, bentonite and the like. In other words, the purpose of using the adsorptive material is to directly remove the contaminant dissolved in the contaminated groundwater by adsorbing it with the adsorbent material present in the filling portion 11a, and to flow into the filling portion 11a. The purpose of the present invention is to finally make the incoming contaminated groundwater harmless to prevent intrusion of contaminants into the pile construction area central part 4a.
[0019]
The impermeable layer ground 2 is a good support layer, the adhesion between the soil in the impermeable layer ground 2 and the pile K is high, and the contaminated groundwater existing in the upper When it does not reach the permeable ground 3, ordinary earth and sand may be used as the filling material M in some cases.
[0020]
Further, as shown in FIG. 1 (f), depending on the type of the filling material M, a drawing step of the outer tube 10 may be performed after the fourth step of filling the material. However, as described in the second embodiment, when an impermeable material such as concrete C is used as the filling material M, the outer tube 10 and the pile K are integrated to increase the strength of the pile K. It is common that the intubation 10 is not pulled out.
However, when the other filling material M is used, the purpose is to directly react with the contaminants in the contaminated groundwater to decompose and remove the contaminants. It is common to adopt a structure in which when the contaminated groundwater flows into the filling portion 11a by performing the extraction of the contaminant 10, the intrusion of the contaminant into the central portion 4a of the pile construction area can be prevented.
[0021]
◎ Second Embodiment As shown in FIG. 2, the second embodiment uses a water-impermeable material such as concrete C as the filling material M to integrate the pile K ′ and the extracorporeal tube 10 ′. It is a construction method performed in.
The construction method of the pile K ′ in the present embodiment includes (1) an extratubation installation step (FIG. 2A), (2) an excavation and cleaning step inside the extracorporeal pipe (FIG. 2B), and (3). The pile driving step (FIGS. 2C and 2D) and the material filling step (FIG. 2E) are performed in the same manner as in the first embodiment. A similar construction method can be adopted for.
On the other hand, the difference from the first embodiment is that after the material filling step, which is the fourth step, the extracorporeal tube 10 ′ is integrated with the pile K ′ without being pulled out, thereby increasing the strength and the like of the pile K ′. It was decided.
[0022]
Also, as shown in FIG. 2, in the second embodiment, studs and protrusions 10′a, as shown in FIG. Generally, K′1 is provided. That is, in the present embodiment, in the material filling step, which is the fourth step, the filling portion 11'a formed between the extracorporeal tube 10 'and the pile K' is filled with concrete C or the like as the filling material M. However, by providing the projections 10'a and K'1 on the inner peripheral surface of the extracorporeal tube 10 'and the head of the pile K', the adhesion between the concrete C or the like and the extracorporeal tube 10 'and the pile K' is increased. The purpose of the structure is to increase the strength of the head of the pile K 'and the strength of the pile K' by adopting a structure of being integrated.
[0023]
Regarding the heads of the piles K and K ′, whether they are buried in the ground of the upper permeable ground 1 (in the case of FIG. 2) or project above the ground (in the case of FIG. 1), there is no problem. Absent.
[0024]
【The invention's effect】
As described above, the present invention has an effect that it is possible to prevent contaminants from penetrating into the lower permeable layer ground at the time of driving a pile by installing an extrapolation pipe. In addition, by filling the space between the extrapolated pipe and the cast pile with the various materials described above, it is possible to prevent infiltration of contaminants into the center of the pile construction area after placing the pile, and to fill the lower permeable layer ground. This has the effect that contamination of clean groundwater contained therein can be prevented.
[Brief description of the drawings]
FIG. 1 is a side sectional view showing a first embodiment of a pile construction method, in which (a) is a process of installing an extratubular tube, (b) is a process of excavating and cleaning the inside of the extratubular tube, and (c) and (d). Shows a pile driving step, (e) shows a material filling step, and (f) shows a step of pulling out an extratubular tube.
FIGS. 2A and 2B are side sectional views showing a second embodiment of a pile construction method, wherein FIG. 2A is a step of installing an extratubular tube, FIG. Indicates a pile driving step, and (e) indicates a material filling step.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Upper permeable layer ground 2 Impermeable layer ground 3 Lower permeable layer ground 4 Pile construction area 4a Pile construction area center part 10 Extracorporeal pipe 10'a Projection 11 Pile driving space 11a Filling part K Pile K'1 Projection M Filling material C concrete

Claims (1)

In a pile construction method in which a permeable ground exists above and below an impermeable ground, and an upper permeable ground places piles in the ground having contaminated groundwater containing contaminants,
(B) Installation process of extracorporeal pipes on the upper permeable ground in the pile construction area,
(B) excavation and washing steps inside the extracorporeal tube;
(C) a step of driving a pile into the inside of the extratubular tube,
(D) a filling material for preventing the contaminant from penetrating into the center of the pile construction area ,
A stabilizing material having a property of directly reacting with the contaminant to form an insoluble substance, a decomposing material having a property of decomposing the contaminant to make it harmless by reacting with the contaminant, and adsorbing the contaminant Filling a filling material containing at least one of an adsorbent material between the extrapolation tube and the pile,
A pile construction method comprising the steps of:

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