JP2021085196A - Pile driving method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pile driving construction method which is efficient in terms of time and economy.
In a pile driving method, a slurry 22 containing water-hard powder and water is formed in an excavation hole 21 formed by excavating the ground while supplying excavation liquid to each of a plurality of tubular piles 23. Insert after injecting. When inserting at least one pile 23 other than the last one of the plurality of piles 23, the position of the liquid level of the slurry 22 in the pile is monitored, and the difficulty of inserting the pile is evaluated from the result of the monitoring. Then, based on the pile insertion difficulty, the pile driving when the pile insertion difficulty is evaluated is used as a reference, and the pile insertion promoting means to be applied other than the pile 23 in the subsequent pile driving is adopted or not adopted, or the conditions thereof are maintained. Or make a change.
[Selection diagram] FIG. 2A

Description

The present invention relates to a pile driving construction method and a pile insertion difficulty evaluation method.

In the pre-boring pile method, after injecting cement slurry into an excavation hole formed by excavating the ground, the pile is inserted into the excavation hole and the cement slurry is hardened to fix the pile to the ground. At this time, if the soil on the site is mixed with the cement slurry and the viscosity is increased, the frictional force acting between the pile and the cement slurry becomes high, and as a result, the insertion of the pile may not proceed and may remain high. is there. In such a case, it is necessary to take measures such as displacing the pile up and down, and it takes a long time to perform the pile driving. On the other hand, if the cement slurry contains a dispersant, the thickening of the cement slurry can be suppressed even if the soil at the site is mixed. Patent Document 1 discloses such a dispersant.

Japanese Unexamined Patent Publication No. 2018-127395

However, since the use of the dispersant is accompanied by an increase in cost, it is uneconomical to use the cement slurry containing the dispersant even when the pile does not stay high.

An object of the present invention is to provide a pile driving method that is efficient both in terms of time and economy.

The present invention is a pile driving operation in which each of a plurality of tubular piles is inserted after injecting a slurry containing water-hard powder and water into an excavation hole formed by excavating the ground while supplying excavation liquid. In this method, when inserting at least one pile other than the last one of the plurality of piles, the position of the liquid level of the slurry in the pile is monitored, and it is difficult to insert the pile from the result of the monitoring. Adoption or non-adoption of pile insertion promoting means to be applied other than the piles in the subsequent pile driving or its conditions based on the pile driving when the degree is evaluated and the pile insertion difficulty is evaluated based on the pile insertion difficulty. To maintain or change.

The present invention evaluates the difficulty of inserting a pile when inserting a tubular pile after injecting a slurry containing water-hard powder and water into an excavation hole formed by excavating the ground while supplying excavation liquid. This method monitors the position of the liquid level of the slurry in the pile at the time of inserting the pile, and evaluates the difficulty of inserting the pile from the result of the monitor.

According to the present invention, pile driving can be carried out efficiently both in terms of time and economy.

It is 1st explanatory drawing of the pile driving construction method which concerns on embodiment. It is a 2nd explanatory drawing of the pile driving construction method which concerns on embodiment. It is a 3rd explanatory view of the pile driving construction method which concerns on embodiment. It is a 4th explanatory view of the pile driving construction method which concerns on embodiment. It is a 5th explanatory drawing of the pile driving construction method which concerns on embodiment. It is a 1st explanatory view of the monitor of the position of the liquid level of the slurry in a pile by floating. It is a 2nd explanatory view of the monitor of the position of the liquid level of the slurry in a pile by floating. It is a 3rd explanatory view of the monitor of the position of the liquid level of the slurry in the pile by floating. It is a 1st explanatory view of the monitor of the position of the liquid level of the slurry in a pile by a non-contact displacement meter. It is a 2nd explanatory view of the monitor of the position of the liquid level of the slurry in a pile by a non-contact displacement meter.

Hereinafter, embodiments will be described in detail.

The pile driving method according to the embodiment is a pre-boring pile method, and in this pile driving method, each of a plurality of tubular piles is formed into an excavation hole formed by excavating the ground while supplying excavation liquid. , Water-hard powder and a slurry containing water are injected and then inserted.

Specifically, first, as shown in FIG. 1A, the ground 20 is excavated with the auger 10 to form the excavation hole 21. At this time, the excavation liquid is supplied from the tip of the auger 10 via a pipe provided in the auger 10. The excavation liquid is generally water, but when the ground 20 is fragile, water may contain bentonite, carboxymethyl cellulose (CMC), or the like. By supplying this excavation liquid, the excavation resistance is reduced and the soil excavated in the excavation hole 21 is turned into mud. The muddy soil is discharged to the outside of the hole by the transport mechanism of the auger 10.

Then, as shown in FIG. 1B, when the excavation hole 21 reaches a predetermined depth, the excavation and the supply of the excavation liquid are stopped. The supply amount of excavation liquid (water injection rate when the excavation liquid is water) when excavating the ground 20 up to this point to form the excavation hole 21 reduces the excavation resistance and makes the soil in the hole muddy. Therefore, it is preferably 30% or more, more preferably 40% or more, and further preferably 50% or more with respect to the volume of the completed excavation hole 21. When the supply amount of the excavation liquid is small, the amount of mud discharged is reduced and the construction cost can be reduced, but the effect of reducing the viscosity of the slurry to be injected later is reduced, so that the slurry is easily thickened. Therefore, the supply amount of the excavation liquid is preferably 100% from the viewpoint that the action and effect that the pile driving can be carried out efficiently in terms of time and economy, which will be described later, can be remarkably obtained. Below, it is more preferably 90% or less, still more preferably 80% or less. The amount of excavated liquid supplied can be roughly estimated and set from a preliminary boring survey and construction results in the vicinity.

Subsequently, as shown in FIG. 1C, while pulling up the auger 10, the slurry 22 containing the hydraulic powder and water is injected into the excavation hole 21 from the tip thereof through the pipe provided in the auger 10.

The "hydraulic powder" in the present application is a powder having physical properties that is cured by a hydration reaction. Examples of such hydraulic powder include cement, gypsum and the like. Examples of cement include ordinary Portland cement, early-strength Portland cement, ultra-early-strength Portland cement, sulfate-resistant Portland cement, low-heat Portland cement, white Portland cement, eco-cement and the like. The hydraulic powder preferably contains one or more of these cements.

The mass percentage of the ratio of the water content to the hydraulic powder content in the slurry 22 (hereinafter referred to as “W / C”) is determined from the viewpoint of increasing the fluidity of the slurry 22 and obtaining excellent workability. It is preferably 30% by mass or more, more preferably 40% by mass or more, and further preferably 50% by mass or more. When the W / C is low, the strength of the cured product of the slurry 22 can be increased, but the slurry 22 tends to thicken. Therefore, the W / C is preferably less than 100% by mass from the viewpoint that the action and effect that the pile driving can be carried out efficiently in terms of time and economy, which will be described later, can be remarkably obtained. , More preferably 80% by mass or less, still more preferably 70% by mass or less.

A slurry 22 of a root hardening liquid having a relatively low W / C is injected into the drilling hole 21 at its tip, and the composition of the slurry 22 is changed in the middle, and W is placed on the slurry 22 of the root hardening liquid. The slurry 22 of the pile circumference fixing liquid having a relatively high / C may be injected.

A dispersant may be added to the slurry 22 from the viewpoint of increasing the fluidity and obtaining excellent workability. Examples of such a dispersant include the dispersant composition disclosed in Patent Document 1.

The dispersant composition disclosed in Patent Document 1 includes a polymer having a monomer unit having a carboxylic acid group (hereinafter referred to as “component (A)”) and a sugar compound having a molecular weight of 1000 or less (hereinafter referred to as “(B)). It is an aqueous solution containing "component") and having a pH of 7.5 or less at 22 ° C.

Examples of the component (A) include polyacrylic acid, polymethacrylic acid, acrylic acid / maleic acid copolymers, and salts thereof. Examples of the salt include alkali metal salts, alkaline earth metal salts, ammonium salts, alkylammonium salts and the like. The component (A) preferably contains one or more of these, and more preferably contains polyacrylic acid or a salt thereof from the viewpoint of increasing the fluidity of the slurry 22 and obtaining excellent workability. It is preferable to contain a sodium salt of polyacrylic acid and / or an ammonium salt of polyacrylic acid.

The content of the component (A) in the dispersant composition is preferably 30% by mass or more, more preferably 40% by mass or more, still more preferably 40% by mass or more, from the viewpoint of increasing the fluidity of the slurry 22 and obtaining excellent workability. It is 50% by mass or more, preferably 90% by mass or less, more preferably 80% by mass or less, and further preferably 70% by mass or less.

Examples of the component (B) include sugars, sugar alcohols and the like. Examples of saccharides include monosaccharides such as glucose, fructose, galactose and mannose; disaccharides such as saccharose; trisaccharides and the like. Examples of sugar alcohols include sorbitol and the like. The component (B) preferably contains one or more of these, and is one of saccharose, glucose, maltose, and lactose from the viewpoint of increasing the fluidity of the slurry 22 and obtaining excellent workability. It is more preferable to contain one or more kinds, and it is more preferable to contain saccharose.

The content of the component (B) in the dispersant composition is preferably 3% by mass or more, more preferably 5% by mass or more, still more preferably 5% by mass or more, from the viewpoint of increasing the fluidity of the slurry 22 and obtaining excellent workability. It is 10% by mass or more, preferably 60% by mass or less, more preferably 45% by mass or less, and further preferably 30% by mass or less.

The mass ratio of the content of the component (A) to the content of the component (B) in the dispersant composition is preferably 0.5 or more from the viewpoint of increasing the fluidity of the slurry 22 and obtaining excellent workability. It is more preferably 1 or more, further preferably 2 or more, and preferably 10 or less, more preferably 6 or less, still more preferably 4 or less.

The pH of the dispersant composition at 22 ° C. is preferably 7 or less, more preferably 6.9 or less, and preferably 2 from the viewpoint of increasing the fluidity of the slurry 22 and obtaining excellent workability. Above, more preferably 3 or more, still more preferably 4 or more.

The dispersant composition also includes acids, defoamers, water-soluble polymer compounds, air entrainers, cement wetting agents, swelling agents, waterproofing agents, retarding agents, quick-setting agents, thickeners, coagulants, etc. It may contain a drying shrinkage reducing agent, a strength enhancing agent, a curing accelerator, a preservative and the like.

The amount of the dispersant composition added to the slurry 22 is such that the sum of the contents of the components (A) and the components (B) is a water-hard powder from the viewpoint of increasing the fluidity of the slurry 22 and obtaining excellent workability. The amount is preferably 0.1% by mass or more, more preferably 0.4% by mass or more, and preferably 2.0% by mass or less from the viewpoint of cost reduction. The amount is preferably 1.2% by mass or less.

Then, as shown in FIG. 1D, a tubular pile 23 lifted by a crane is built and inserted into the excavation hole 21 into which the slurry 22 is injected. At this time, if the pile 23 is divided into a plurality of piles in the length direction and the total weight of the pile 23 connecting them and the hanging tool exceeds the load capacity of the crane, the divided pile 23 is inserted while inserting the divided pile 23. Joint construction may be performed. Further, the pile 23 may be hit or rotated. As shown in FIG. 1E, after the pile 23 is sunk in the excavation hole 21, the slurry 22 hardens and the pile 23 is fixed to the ground 20.

By the way, when the soil in the field is mixed with the slurry in the excavation hole and the viscosity is increased, the frictional force acting between the pile and the slurry around the pile increases, and the difficulty of inserting the pile increases accordingly. .. Further, at this time, the pressure of the slurry in the excavation hole also increases, so that the position of the liquid level of the slurry flowing into the pile rises in response to the pressure. From this, the present inventor has found that the position of the liquid level of the slurry in the pile at this time corresponds to the difficulty of inserting the pile.

Therefore, in the pile driving construction method according to the embodiment, the position of the liquid level of the slurry 22 in the pile 23 is monitored when at least one pile 23 other than the last one of the plurality of piles 23 is inserted. At the same time, the pile insertion difficulty is evaluated from the result of the monitor, and based on the pile insertion difficulty, the pile insertion performed in addition to the pile 23 in the subsequent pile driving is performed based on the pile driving when the pile insertion difficulty is evaluated. Adopt or not adopt promotion means, or maintain or change the conditions.

According to the pile driving construction method according to the embodiment, the position of the liquid level of the slurry 22 in the pile 23 is monitored in this way, the pile insertion difficulty is evaluated from the result of the monitoring, and the pile insertion difficulty is determined. Based on this, based on the pile driving when the pile insertion difficulty is evaluated, the pile insertion promoting means to be applied other than the pile 23 in the subsequent pile driving is adopted or not adopted, or the conditions are maintained or changed, and the pile insertion difficulty Since the construction conditions are adjusted according to the above conditions, pile driving can be carried out efficiently in terms of time and economy.

At this time, the evaluation of the difficulty of inserting the pile based on the monitor of the position of the liquid level of the slurry 22 in the pile 23 is the position of the liquid level of the slurry 22 in the pile 23 itself when the pile 23 is inserted to a predetermined reference depth. Can be done based on. In this case, it can be evaluated that the higher the position of the liquid level of the slurry 22 in the pile 23, the higher the difficulty of inserting the pile. Further, the evaluation of the difficulty of inserting the pile based on the monitor of the position of the liquid level of the slurry 22 in the pile 23 is the insertion of the pile 23 when the position of the liquid level of the slurry 22 in the pile 23 rises to a predetermined reference position. It can also be done based on depth. In this case, it can be evaluated that the shallower the insertion depth of the pile 23, the higher the difficulty of inserting the pile.

At least one pile 23 that monitors the position of the liquid level of the slurry 22 in the pile 23 is the first of the plurality of piles 23 from the viewpoint of adjusting the construction conditions according to the difficulty of inserting the pile from the initial stage of construction. It is preferable to include the first pile 23 of the above. The first pile 23 may be a pile 23 on which a structure such as a building is built and is actually used for supporting the pile 23, and no structure is built on the pile 23. The pile 23 may be used only for setting the construction conditions.

The stake 23, which monitors the position of the liquid level of the slurry 22 in the stake 23, may include the first stake 23 to be piled into each region for each region of different soil quality. In this way, it is possible to adjust the construction conditions according to the difficulty of inserting piles for each soil quality. Further, the piles 23 for monitoring the position of the liquid level of the slurry 22 in the piles 23 may be all the piles 23 except the last one. In this way, it is possible to finely adjust the construction conditions according to the difficulty of inserting the pile.

As shown in FIGS. 2A to 2C, the position of the liquid level of the slurry 22 in the pile 23 can be monitored by confirming the position of the float 30 floating on the liquid surface of the slurry 22. For example, when determining the difficulty of inserting a pile based on the position of the liquid level of the slurry 22 in the pile 23 when the pile 23 is inserted to a predetermined reference depth, the protrusion of the float 30 from the upper end of the pile 23 From the presence or absence, when there is protrusion of the float 30, the position of the liquid level of the slurry 22 is high and the difficulty of inserting the pile is relatively high, while when there is no protrusion of the float 30, the position of the liquid level of the slurry 22 is low. If the pile insertion difficulty is relatively low, a two-step evaluation can be performed. Further, if the marks 31 are provided at predetermined intervals in the length direction of the float 30, as shown in FIGS. 2B and 2C, the larger the number of the marks 31 that can be confirmed when the float 30 is projected. If the difficulty of inserting the pile is high, it is possible to perform a more multi-step evaluation. Examples of the means for confirming the position of the float 30 include the use of cameras and drones installed inside and outside the venue, in addition to visual inspection.

As shown in FIGS. 3A and 3B, the position of the liquid level of the slurry 22 in the pile 23 can be monitored by a non-contact displacement meter 40 such as a laser displacement sensor provided at the opening of the pile 23. For example, when the evaluation of the difficulty of inserting a pile is performed based on the position of the liquid level of the slurry 22 in the pile 23 when the pile 23 is inserted to a predetermined reference depth, the position of the liquid level of the slurry 22 in the pile 23. Depending on the situation, the difficulty of inserting piles can be evaluated continuously or discontinuously in multiple stages. The non-contact displacement meter 40 may be provided at a wire portion that is a hanging tool of the pile 23 or at the tip portion of the crane.

As a pile insertion promoting means other than the pile 23 in the subsequent pile driving based on the pile driving when the pile insertion difficulty is evaluated based on the pile insertion difficulty, for example, a dispersant in the slurry 22 is used. Addition or increase in the amount of addition thereof can be mentioned. In this case, the adoption or non-adoption of the pile insertion promoting means, or the maintenance or change of the conditions thereof, is used in the subsequent pile driving based on the slurry 22 used in the pile driving when the pile insertion difficulty is evaluated. The addition or non-addition of the dispersant to the slurry 22 or the maintenance, reduction or increase in the amount of the dispersant added is included.

Specifically, for example, when the slurry 22 used for pile driving when evaluating the pile insertion difficulty does not contain a dispersant, and the pile insertion difficulty is higher than a predetermined setting standard, the pile insertion difficulty is set. Based on the slurry 22 used in the pile driving at the time of evaluation, in the slurry 22 used in the subsequent pile driving, the dispersant is added according to the difference from the setting standard of the pile insertion difficulty. When the pile insertion difficulty matches the setting standard, or when the pile insertion difficulty is lower than the setting standard, the slurry 22 used for pile driving when the pile insertion difficulty is evaluated is used as a reference for the slurry 22. The amount of the dispersant added is maintained, that is, the non-addition of the dispersant to the slurry 22 is continued.

When the slurry 22 used for pile driving when evaluating the pile insertion difficulty contains a dispersant and the pile insertion difficulty matches the setting criteria, it was used for the pile driving when evaluating the pile insertion difficulty. With the slurry 22 as a reference, the amount of the dispersant added to the slurry 22 used in the subsequent pile driving is maintained. When the pile insertion difficulty is higher than the setting standard, the slurry 22 used in the pile driving when the pile insertion difficulty is evaluated is used as a reference, and the slurry 22 used in the subsequent pile driving is based on the pile insertion difficulty setting standard. The amount of the dispersant added is increased according to the difference between the above. When the pile insertion difficulty is lower than the setting standard, the slurry 22 used in the pile driving when the pile insertion difficulty is evaluated is used as a reference, and the slurry 22 used in the subsequent pile driving is based on the pile insertion difficulty setting standard. The amount of the dispersant added is reduced according to the difference between the above, and in some cases, the dispersant is not added to the slurry 22.

Further, as a pile insertion promoting means other than the pile 23 in the subsequent pile driving based on the pile driving when the pile insertion difficulty is evaluated based on the pile insertion difficulty, the supply amount of excavation liquid is used. Increased amount can be mentioned. In this case, the maintenance or change of the pile insertion promoting means is to maintain or change the supply amount of excavation liquid in the subsequent pile driving based on the supply amount of the excavation liquid in the pile driving when the difficulty of pile insertion is evaluated. It will include weight loss or weight increase.

Specifically, when the pile insertion difficulty is higher than the setting standard, and when the pile insertion difficulty matches the setting standard, the amount of excavation liquid supplied in the pile driving when the pile insertion difficulty is evaluated is used as a reference. Maintain the supply of drilling fluid for subsequent pile driving. Based on the supply amount of excavation liquid in pile driving when the pile insertion difficulty is evaluated, the supply amount of excavation liquid in subsequent pile driving is increased according to the difference from the setting standard of pile insertion difficulty. When the pile insertion difficulty is lower than the setting standard, the supply amount of excavation liquid in the pile driving after the evaluation of the pile insertion difficulty is used as a reference, and the supply amount of the excavation liquid in the subsequent pile driving is determined by the pile insertion difficulty. Reduce the weight according to the difference from the setting standard.

The control of the pile insertion promoting means may be performed only by the control by the dispersant added to the slurry 22, or only by the control by the supply amount of the excavation liquid, or may be performed by combining these controls.

The present invention is useful in the technical fields of pile driving construction methods and pile insertion difficulty evaluation methods.

10 Ogre 20 Ground 21 Drilling hole 22 Slurry 23 Pile 30 Float 31 Mark 40 Non-contact displacement meter

Claims (10)

This is a pile driving method in which each of a plurality of tubular piles is inserted after injecting a slurry containing water-hard powder and water into an excavation hole formed by excavating the ground while supplying excavation liquid. ,
When inserting at least one pile other than the last one of the plurality of piles, the position of the liquid level of the slurry in the pile is monitored, and the difficulty of inserting the pile is evaluated from the result of the monitoring. Based on the pile insertion difficulty, based on the pile driving when the pile insertion difficulty is evaluated, the adoption or non-adoption of the pile insertion promoting means to be applied other than the pile in the subsequent pile driving, or the maintenance or change of the conditions thereof. Pile driving construction method. The pile driving method according to claim 1, wherein at least one pile for monitoring the position of the liquid level of the slurry in the pile includes the first one of the plurality of piles. The pile driving method according to claim 1 or 2, wherein the result of the monitor is the position of the liquid level of the slurry in the pile when the pile is inserted to a predetermined reference depth. The pile driving method according to any one of claims 1 to 3, wherein the mass percentage of the ratio of the content of the water to the content of the water-hard powder in the slurry is less than 100% by mass. The pile driving according to any one of claims 1 to 4, wherein the supply amount of the excavation liquid when excavating the ground to form the excavation hole is 100% or less with respect to the volume of the excavation hole. Construction method. Adoption or non-adoption of the pile insertion promoting means, or maintenance or change of the conditions thereof is to the slurry used in the subsequent pile driving when the slurry used in the pile driving when evaluating the pile insertion difficulty is used as a reference. The pile driving method according to any one of claims 1 to 5, which comprises the addition or non-addition of the dispersant, or the maintenance, reduction or increase in the amount of the dispersant. When the maintenance or change of the pile insertion promoting means is based on the supply amount of the excavation liquid in the pile driving when the pile insertion difficulty is evaluated, the maintenance or reduction of the supply amount of the excavation liquid in the subsequent pile driving is performed. Alternatively, the pile driving method according to any one of claims 1 to 6, which includes an increase in the amount. The pile driving construction method according to any one of claims 1 to 7, wherein the position of the liquid level of the slurry in the pile is monitored by confirming the position of the float floating on the liquid surface of the slurry. The pile driving construction method according to any one of claims 1 to 8, wherein the position of the liquid level of the slurry in the pile is monitored by a non-contact displacement meter. This is a method for evaluating the difficulty of inserting piles when a tubular pile is inserted after injecting a slurry containing water-hard powder and water into an excavation hole formed by excavating the ground while supplying excavation liquid. ,
A method for evaluating the difficulty of inserting a pile, which monitors the position of the liquid level of the slurry in the pile at the time of inserting the pile and evaluates the difficulty of inserting the pile from the result of the monitoring.

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