JP7332447B2 - Piling construction method - Google Patents

Description

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

In the pre-boring pile construction method, after injecting a cement slurry into a borehole formed by excavating the ground, a pile is inserted into the borehole and the cement slurry is hardened to fix the pile to the ground. At this time, if the cement slurry is mixed with soil from the site and thickened, the frictional force acting between the pile and the cement slurry will increase, and as a result, the insertion of the pile will not progress and may stop at a high level. be. In such a case, it is necessary to take countermeasures such as vertically displacing the piles, and it takes a long time to drive the piles. On the other hand, if the cement slurry contains a dispersant, it is possible to suppress thickening of the cement slurry even if the soil on the site is mixed. Patent Literature 1 discloses such a dispersant.

JP 2018-127395 A

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

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

The present invention is a pile driving work in which each of a plurality of tubular piles is inserted into a drill hole formed by drilling the ground while supplying a drilling fluid, after injecting a slurry containing hydraulic powder and water. In the method, when inserting at least one pile excluding the last one of the plurality of piles, the position of the liquid surface of the slurry in the pile is monitored, and from the result of the monitoring, it is difficult to insert the pile. Evaluate the degree of difficulty of inserting the pile, and based on the degree of difficulty of inserting the pile, based on the pile driving when the degree of difficulty of inserting the pile is evaluated, adoption or non-adoption of pile insertion promoting means other than piles in subsequent pile driving, or conditions thereof shall be maintained or changed.

The present invention evaluates the difficulty of pile insertion when inserting a tubular pile after injecting a slurry containing hydraulic powder and water into a borehole formed by excavating the ground while supplying a drilling fluid. The method monitors the position of the liquid surface of the slurry in the pile when the pile is inserted, and evaluates the difficulty of inserting the pile from the results of the monitoring.

ADVANTAGE OF THE INVENTION According to this invention, construction of piling can be efficiently performed in terms of time and economy.

It is the 1st explanatory view of the pile driving construction method concerning an embodiment. It is the 2nd explanatory view of the pile driving construction method concerning an embodiment. It is the 3rd explanatory view of the pile driving construction method concerning an embodiment. It is the 4th explanatory view of the pile driving construction method concerning an embodiment. It is the 5th explanatory view of the piling construction method concerning an embodiment. FIG. 10 is a first illustration of monitoring the position of the liquid surface of the slurry in the pile by floating; FIG. 11 is a second illustration of monitoring the position of the liquid surface of the slurry in the pile by floating; FIG. 11 is a third illustration of monitoring the position of the liquid surface of the slurry in the pile by floating; FIG. 10 is a first explanatory view of monitoring the position of the liquid surface of the slurry in the pile using a non-contact displacement gauge; It is a second explanatory diagram of monitoring the position of the liquid surface of the slurry in the pile by the non-contact displacement gauge.

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 drilled into the ground while supplying the drilling fluid into the excavation hole. , after injecting a slurry containing hydraulic powder and water.

Specifically, first, as shown in FIG. 1A, the ground 20 is excavated by the auger 10 to form the excavation hole 21 . At this time, drilling fluid is supplied from the tip of the auger 10 via a pipe. The drilling fluid is generally water, but if the ground 20 is fragile, it may be water containing bentonite, carboxymethyl cellulose (CMC), or the like. By supplying the drilling fluid, the drilling resistance is reduced and the soil drilled in the drill hole 21 is turned into mud. The sludged soil is discharged out of the hole by the conveying mechanism of the auger 10 .

Next, as shown in FIG. 1B, when the drilled hole 21 reaches a predetermined depth, the drilling and the supply of the drilling fluid are stopped. The supply amount of the drilling fluid (the water injection rate when the drilling fluid is water) when excavating the ground 20 to form the drilling hole 21 so far is from the viewpoint of reducing the drilling resistance and turning the soil in the hole into mud. Therefore, it is preferably 30% or more, more preferably 40% or more, and still more preferably 50% or more of the volume of the completed borehole 21 . If the amount of drilling fluid supplied is small, the amount of sludge discharged is reduced, and construction costs can be reduced. Therefore, from the viewpoint that it is possible to significantly obtain the effect of being able to carry out piling work efficiently in terms of time and economy, which will be described later, the supply amount of the drilling fluid is preferably 100%. Below, more preferably 90% or less, still more preferably 80% or less. The supply amount of the drilling fluid can be set by roughly estimating from a preliminary boring survey and construction results in the vicinity.

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

A "hydraulic powder" in the present application is a powder having a physical property of being hardened by a hydration reaction. Examples of such hydraulic powder include cement and gypsum. Examples of cement include ordinary Portland cement, high-early-strength Portland cement, ultra-early-strength Portland cement, sulfate-resistant Portland cement, low-heat Portland cement, white Portland cement, and ecocement. The hydraulic powder preferably contains one or more of these cements.

The mass percentage (hereinafter referred to as "W / C") of the ratio of the water content to the hydraulic powder content in the slurry 22 is, from the viewpoint of improving 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 still more preferably 50% by mass or more. When the W/C is low, the strength of the hardened slurry 22 can be increased, but the viscosity of the slurry 22 tends to increase. Therefore, from the viewpoint that it is possible to significantly obtain the effect of being able to perform piling construction efficiently in terms of time and economy, which will be described later, W / C is preferably less than 100% by mass. , more preferably 80% by mass or less, and still more preferably 70% by mass or less.

Into the excavated hole 21, a slurry 22 of foot protection liquid having a relatively low W/C is injected into the tip, and the composition of the slurry 22 is changed on the way so that W A slurry 22 of a pile perimeter fixing solution having a relatively high /C may be injected.

A dispersant may be added to the slurry 22 from the viewpoint of improving fluidity and obtaining excellent workability. Such a dispersant includes, for example, the dispersant composition disclosed in Patent Document 1.

The dispersant composition disclosed in Patent Document 1 comprises 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) (referred to as "component") and having a pH of 7.5 or less at 22°C.

Component (A) includes, for example, polyacrylic acid, polymethacrylic acid, acrylic acid/maleic acid copolymers, and salts thereof. Examples of salts 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 from the viewpoint of increasing the fluidity of the slurry 22 and obtaining excellent workability, it is more preferable to contain polyacrylic acid or a salt thereof. More preferably, it contains a sodium salt of polyacrylic acid and/or an ammonium salt of polyacrylic acid.

The content of component (A) in the dispersant composition is preferably 30% by mass or more, more preferably 40% by mass or more, and still more preferably It is 50% by mass or more, preferably 90% by mass or less, more preferably 80% by mass or less, and even more preferably 70% by mass or less.

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

The content of component (B) in the dispersant composition is preferably 3% by mass or more, more preferably 5% by mass or more, and still more preferably It is 10% by mass or more, preferably 60% by mass or less, more preferably 45% by mass or less, and even more 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 improving the fluidity of the slurry 22 and obtaining excellent workability. It is more preferably 1 or more, still more 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. or more, more preferably 3 or more, and still more preferably 4 or more.

The above dispersant composition may also contain an acid, an antifoaming agent, a water-soluble polymer compound, an air entraining agent, a cement wetting agent, an expanding agent, a waterproofing agent, a retarder, a quick setting agent, a thickening agent, a flocculating agent, A drying shrinkage reducing agent, a strength enhancer, a hardening accelerator, a preservative, etc. may be contained.

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

Then, as shown in FIG. 1D, a cylindrical pile 23 lifted by a crane is erected and inserted into the drilled hole 21 into which the slurry 22 has been injected. At this time, the pile 23 is divided into a plurality of pieces in the length direction, and if the total weight of the pile 23 and the lifting device connecting them exceeds the load capacity of the crane, while inserting the divided pile 23, Joint construction may be performed. Also, the pile 23 may be hit or rotated. In addition, as shown in FIG. 1E , after the pile 23 is sunk in the excavation hole 21 , the pile 23 is fixed to the ground 20 by hardening the slurry 22 .

By the way, if the soil in the drilled hole is mixed with the soil of the site and thickened, the frictional force acting between the pile and the slurry around the pile will increase, which will make it more difficult to insert the pile. . At this time, the pressure of the slurry in the excavation hole also increases, so the position of the surface of the slurry that has flowed into the pile rises corresponding to the pressure. From this, the inventor found that the position of the liquid surface of the slurry in the pile at this time corresponds to the difficulty of inserting the pile.

Therefore, in the pile driving method according to the embodiment, the position of the liquid surface of the slurry 22 in the pile 23 is monitored when inserting at least one pile 23 excluding the last one of the plurality of piles 23. 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 on the pile other than the pile 23 in the subsequent pile driving based on the pile driving when the pile insertion difficulty is evaluated. Adopt or reject facilitative measures, or maintain or change the terms thereof.

According to the pile driving method according to the embodiment, the position of the liquid surface 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 Based on this, based on the pile driving when evaluating the pile insertion difficulty, the adoption or non-adoption of the pile insertion promotion means applied to other than the pile 23 in the subsequent pile driving, or the condition is maintained or changed, and the pile insertion difficulty Since the construction conditions are adjusted according to the conditions, it is possible to efficiently perform the construction of piling in terms of time and economy.

At this time, the evaluation of the pile insertion difficulty based on the monitoring of the position of the liquid surface of the slurry 22 in the pile 23 is the position of the liquid surface of the slurry 22 in the pile 23 when the pile 23 is inserted to a predetermined reference depth. can be done on the basis of In this case, it can be evaluated that the higher the position of the liquid surface of the slurry 22 in the pile 23, the higher the pile insertion difficulty. In addition, the evaluation of the pile insertion difficulty based on the monitoring of the position of the liquid surface of the slurry 22 in the pile 23 is performed by inserting the pile 23 when the position of the liquid surface 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 is, the higher the pile insertion difficulty is.

At least one pile 23 for monitoring the position of the liquid surface of the slurry 22 in the pile 23 is the first among the plurality of piles 23 from the viewpoint of adjusting the construction conditions according to the difficulty of inserting the pile from the beginning of construction. preferably includes the first pile 23 of the . This first pile 23 may be a pile 23 on which a structure such as a building is built and which is actually used to support it, or a structure is not built on it, The piles 23 may be used only for setting construction conditions.

The stakes 23 that monitor the position of the liquid surface of the slurry 22 in the stakes 23 may include the first stake 23 that is staked in each region for each region with different soil quality. By doing so, it is possible to adjust the construction conditions according to the difficulty of inserting piles for each type of soil. Moreover, the piles 23 for monitoring the position of the liquid surface of the slurry 22 in the piles 23 may be all the piles 23 except for the last one. By doing so, it is possible to finely adjust the construction conditions according to the degree of difficulty in inserting the pile.

The position of the liquid surface of the slurry 22 in the pile 23 can be monitored by confirming the position of a float 30 floating on the liquid surface of the slurry 22, as shown in FIGS. 2A-C. For example, when determining the pile insertion difficulty level based on the position of the liquid surface 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 When the float 30 protrudes, the liquid level of the slurry 22 is high, and the difficulty of inserting the pile is relatively high. If the pile insertion difficulty is relatively low, a two-step evaluation can be made. Also, if the marks 31 are provided at predetermined intervals in the length direction of the float 30, as shown in FIGS. If the pile insertion difficulty is high, a multi-level evaluation can be performed. As means for confirming the position of the float 30, in addition to visual observation, for example, cameras installed inside and outside the venue, the use of drones, and the like can be used.

The position of the liquid surface of the slurry 22 in the pile 23 can also be monitored by a non-contact displacement gauge 40 such as a laser displacement sensor provided at the opening of the pile 23, as shown in FIGS. 3A and 3B. For example, when evaluating the pile insertion difficulty based on the position of the liquid surface of the slurry 22 in the pile 23 when the pile 23 is inserted to a predetermined reference depth, the position of the liquid surface of the slurry 22 in the pile 23 Depending on the conditions, a continuous evaluation or a discontinuous multi-step evaluation can be performed for pile insertion difficulty. Note that the non-contact displacement gauge 40 may be provided at the wire portion that is the hanging tool of the pile 23 or at the tip of the crane.

Based on the pile insertion difficulty, when the pile insertion when evaluating the pile insertion difficulty is used as a reference, the pile insertion promotion means applied to other than the pile 23 in the subsequent pile driving is, for example, adding a dispersant to the slurry 22. addition or an increase in the amount of addition thereof. In this case, the adoption or non-adoption of the pile insertion promotion means, or the maintenance or change of the conditions, is used in the subsequent pile driving when the slurry 22 used in the pile driving when evaluating the pile insertion difficulty is used as a reference. This includes adding or not adding a dispersant to the slurry 22, or maintaining, decreasing, or increasing the amount added.

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

When the slurry 22 used in pile insertion when evaluating the pile insertion difficulty contains a dispersant, when the pile insertion difficulty matches the set standard, it is used in pile driving when evaluating the pile insertion difficulty. Based on the slurry 22, the amount of dispersant added to the slurry 22 used in subsequent piling is maintained. When the pile insertion difficulty is higher than the set standard, the slurry 22 used in pile driving when evaluating the pile insertion difficulty is used as a reference, and the slurry 22 used in subsequent pile driving is added from the set standard of pile insertion difficulty. The amount of dispersant added is increased according to the difference in When the pile insertion difficulty is lower than the set standard, the slurry 22 used in pile driving when evaluating the pile insertion difficulty is used as a reference, and the slurry 22 used in subsequent pile driving is set from the set standard of pile insertion difficulty. The amount of the dispersant to be added is reduced according to the difference in , and in some cases, no dispersant is added to the slurry 22 .

In addition, as a means for promoting pile insertion other than the pile 23 in the subsequent pile driving when the pile driving when evaluating the pile insertion difficulty is based on the pile insertion difficulty, the amount of supply of the drilling fluid is increased. An increase is included. In this case, the maintenance or change of the pile insertion promoting means is based on the supply amount of drilling fluid in pile driving when evaluating the difficulty of pile insertion, maintaining the supply amount of drilling fluid in subsequent pile driving, It will include dose reductions or dose increases.

Specifically, when the pile insertion difficulty is higher than the set standard, when the pile insertion difficulty matches the set standard, the supply amount of drilling fluid in pile driving when evaluating the pile insertion difficulty is used as a standard, Maintain the supply of drilling fluid in subsequent pilings. Based on the amount of supply of drilling fluid in pile driving when evaluating the difficulty of pile insertion, the amount of supply of drilling fluid in subsequent pile driving is increased according to the difference from the set standard of difficulty of inserting pile. When the pile insertion difficulty is lower than the set standard, the amount of drilling fluid supplied during pile driving when evaluating the pile insertion difficulty is used as the standard, and the amount of drilling fluid supplied during subsequent pile driving is calculated as the pile insertion difficulty. Reduce the dose according to the difference from the established standard.

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

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

10 Auger 20 Ground 21 Drilling hole 22 Slurry 23 Pile 30 Float 31 Marker 40 Non-contact displacement gauge

Claims (10)

A pile driving method in which each of a plurality of tubular piles is inserted into an excavation hole formed by excavating the ground while supplying a drilling fluid, after injecting a slurry containing hydraulic powder and water. ,
When inserting at least one pile excluding the last one of the plurality of piles, monitor the position of the liquid surface of the slurry in the pile, and evaluate the pile insertion difficulty from the result of the monitor, Based on the said pile insertion difficulty, based on the pile driving when the said pile insertion difficulty is evaluated, adoption or non-adoption of pile insertion promoting means other than piles in subsequent pile driving, or maintenance or change of the conditions , piling construction method. 2. The piling construction method according to claim 1, wherein the at least one pile for monitoring the position of the liquid level of the slurry in the pile includes the first pile among the plurality of piles. 3. The pile driving method according to claim 1 or 2, wherein the result of the monitoring is the position of the liquid surface of the slurry in the pile when the pile is inserted to a predetermined reference depth. The piling construction method according to any one of claims 1 to 3, wherein the mass percentage of the ratio of the water content to the hydraulic powder content in the slurry is less than 100 mass%. 5. The piling according to any one of claims 1 to 4, wherein the supply amount of said drilling fluid when said ground is excavated to form said drilled hole is 100% or less of the volume of said drilled hole. Construction method. The adoption or non-adoption of the pile insertion promotion means, or the maintenance or change of the conditions thereof, is based on the slurry used in the pile driving when the pile insertion difficulty is evaluated, and the slurry used in the subsequent pile driving. The pile driving method according to any one of claims 1 to 5, including adding or not adding a dispersant or maintaining, reducing or increasing the amount of the dispersant. The maintenance or change of the pile insertion promotion means maintains or reduces the supply amount of the drilling fluid in the subsequent pile driving when the supply amount of the drilling fluid in the pile driving when the pile insertion difficulty is evaluated is used as a reference. Or the pile driving construction method according to any one of claims 1 to 6, including increasing the weight. 8. The pile driving method according to any one of claims 1 to 7, wherein the position of the liquid surface of the slurry in the pile is monitored by confirming the position of a float floating on the liquid surface of the slurry. 8. The pile driving method according to any one of claims 1 to 7 , wherein the position of the liquid surface of the slurry in the pile is monitored by a non-contact displacement gauge. A pile insertion difficulty evaluation method when inserting a tubular pile after injecting a slurry containing hydraulic powder and water into a borehole formed by excavating the ground while supplying a drilling fluid, ,
A pile insertion difficulty evaluation method, comprising: monitoring the position of the liquid surface of the slurry in the pile when the pile is inserted; and evaluating the pile insertion difficulty from the result of the monitoring.

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