JP4658685B2 - Calculation method of pulling resistance of knotted pile using support pressure acting on inclined surface of enlarged diameter part, calculation method of indentation resistance, design method of knotted pile, knotted pile - Google Patents

Description

  The present invention relates to a method for calculating the pulling resistance force of the knotted pile using the bearing pressure acting on the inclined surface of the enlarged diameter portion, a method for calculating the pushing resistance force, a method for designing the knotted pile, a method for calculating the knotted pile, and , Regarding knotted piles.

  2. Description of the Related Art Conventionally, as a foundation pile that supports the load of a building, a knotted pile having a diameter-expanded portion at the middle or lower end in the longitudinal direction has been widely used. According to the knotted pile, by providing the enlarged diameter portion, the transmission area of the load from the foundation pile to the ground is increased, so that the vertical support force and the pulling resistance force can be increased.

As a method for evaluating the pulling resistance force of the knotted pile, for example, in Patent Document 1, when the knotted pile is pulled out, the ground directly above the enlarged diameter portion has an effective height that is twice the diameter of the enlarged diameter portion. It is described that a value obtained by multiplying the peripheral area of the cylinder by the shear strength of the ground is designed as the drawing resistance force of the enlarged diameter portion, assuming that the cylinder is sheared into a cylindrical shape.
Japanese Patent Laid-Open No. 2002-21070

  However, in the above-mentioned method for calculating the pulling resistance force of the enlarged diameter portion, the effective height of the shear surface is uniquely set to twice the value of the enlarged diameter portion, so that the difference in diameter between the enlarged diameter portion and the shaft portion is small. In addition, when the difference in diameter between the enlarged diameter portion and the shaft portion is large, there is a problem that the calculated pulling resistance force becomes the same value even though the actual pulling resistance force is different.

  As described above, the method of calculating the pulling resistance force of the knotted pile described in Patent Document 1 cannot always obtain sufficient accuracy, so that the pulling resistance force is underestimated, overdesigned, and costly. In some cases, it becomes expensive, or the pulling resistance force is overestimated, and safety may be impaired.

  Then, an object of this invention is to enable it to calculate correctly the drawing-out resistance force and indentation resistance force of a knot pile.

  The method for calculating the pulling resistance force of the knotted pile according to the present invention is a method of calculating the pulling resistance force of the knotted pile having a diameter-enlarged portion including an inclined surface inclined so that the diameter increases toward the lower side. And calculating the ultimate pulling resistance force borne by the inclined surface based on a product of a horizontal projected area of the inclined surface and a vertical component of the ultimate bearing pressure degree of the ground near the inclined surface. To do.

Further, the method for calculating the pulling resistance force of the knotted pile according to the present invention is a method of calculating the pulling resistance force of the knotted pile having a plurality of enlarged diameter portions including an inclined surface inclined so that the diameter increases toward the lower side. Where N is the number of the enlarged portions, and A _i is the horizontal projected area of the inclined surface of the i-th enlarged portion. A _vi [m ² ] is the ultimate bearing pressure of the ground near the inclined surface of the i-th enlarged portion. P _vi [kN / m ² ], and the reduction coefficient of the inclined surface of the i-th enlarged diameter portion is β _i , the ultimate drawing resistance of the inclined surface of each enlarged diameter portion obtained by the following formula (1) The calculation is based on the sum of forces T [kN].

In the calculation method of the pulling resistance force of the above-mentioned knotted pile, the reduction coefficient β _i may be set to a value of 0.8 or more and 0.9 or less.
Further, it determined by the ultimate bearing capacity power level following equation _{p vi} as the value of the ultimate Bearing force of (2) in the formula (1), the value of _{p vi} obtained by equation (2) is 7500 [kN / ^{m 2} if it is less than, the value of the resulting _{p vi,} if the value of _{p vi} obtained by equation (2) is 7500 [kN / ^{m 2]} or more, using a 7500 [kN / ^{m 2]} The calculation method may be used.
p _vi = 150N (2)

Further, in the method for calculating the pull-out resistance force of the pile with the previous section, when the average of the undrained shear strength near the inclined surface of the i-th enlarged diameter portion which is embedded in the cohesive soil was C _U, the formula As the value of the ultimate support pressure p _vi in (1), the ultimate support pressure degree p _vi is obtained by the following formula (3), and the ultimate support pressure degree p _vi calculated by the formula (3) is 7500 [kN / If less than m ^2] is the ultimate Bearing force of the calculated, if it is intrinsic Bearing force of _{p vi} calculated by equation (3) is 7500 [kN / ^{m 2]} or more, 7500 [kN / M ² ] may be used.
p _vi = 6C _U (3)

Further, the method of calculating the indentation resistance force of the knotted pile according to the present invention is a method of calculating the indentation resistance force of the knotted pile having a diameter-enlarged portion including an inclined surface that is inclined so that the diameter increases toward the upper side. And calculating the ultimate pushing resistance force borne by the inclined surface based on the product of the horizontal projected area of the inclined surface and the vertical component of the ultimate bearing pressure degree of the ground near the inclined surface. And
Further, the method of calculating the indentation resistance force of the knotted pile according to the present invention is a method of calculating the indentation resistance force of the knotted pile having a plurality of enlarged diameter portions including an inclined surface inclined so that the diameter increases toward the upper side. And the number of the enlarged diameter portions is N, and the horizontal projected area of the inclined surface of the i-th enlarged diameter portion is A ′ _vi [m ² ] the ultimate bearing pressure degree of the ground near the inclined surface of the i-th enlarged diameter portion. P ′ _vi [kN / m ² ] and the reduction coefficient of the inclined surface of the i-th enlarged diameter portion is β ′ _i , the limit of the inclined surface of each enlarged diameter portion obtained by the following equation (4) A method for calculating the indentation resistance force of a knotted pile, wherein the calculation is based on the sum T ′ [kN] of indentation resistance force.

  According to the calculation method of pulling resistance force and pushing resistance force of the above-mentioned knotted pile, since the calculation is performed using the vertical projection area of the inclined surface of the enlarged diameter portion, the difference in diameter between the enlarged diameter portion and the pile shaft portion. Can be reflected in the magnitude of the pull-out resistance force and the indentation resistance force, so that the pull-out resistance force and the indentation resistance force of the knotted pile can be calculated more accurately.

  In the method for calculating the pulling resistance, the knotted pile may be a knotted round pile or a knotted wall pile. In the method for calculating the indentation resistance, the knotted pile may be a knotted round pile or a knotted wall pile.

  Furthermore, the present invention is a design method of a knot pile having a plurality of enlarged diameter portions including an inclined surface that is inclined so that the diameter increases toward the lower side, and by the above-described calculation method of the pulling resistance force of the knot pile. It shall include the design method of a pile with a knot characterized by designing so that the calculated pulling resistance may be more than a predetermined standard resistance.

  Further, the present invention is a design method of a knotted pile having a plurality of enlarged diameter portions including an inclined surface inclined so that the diameter increases toward the upper side, which is calculated by the above-described calculation method of the indentation resistance force of the knotted pile It shall include the design method of the pile with a knot characterized by designing so that the indentation resistance force made may become more than predetermined standard resistance force.

In addition, in the design method of a knot pile, the knot pile may be a knot round pile or a knot wall pile.
Moreover, this invention shall include the knot pile characterized by the above-mentioned design method of a knot pile.

  Since the pulling resistance force and pushing resistance force of the enlarged diameter portion of the knotted pile can be obtained more accurately, it is possible to prevent excessive design and underestimation of safety, and to reduce costs or improve safety.

  Hereinafter, an embodiment of a method for calculating the pulling resistance force of a knotted pile according to the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view of a round pile with a knot that is an object of calculation of pulling resistance. As shown in the figure, the round pile 1 with a knot has a columnar pile shaft portion 2, one or more knot portions 3, and an expanded bottom portion 4, and the upper portion thereof is an underground structure of a building (not shown). )It is connected to the. The node portion 3 and the expanded bottom portion 4 correspond to the expanded diameter portion. In addition, the enlarged diameter part is a part where the pile diameter is constant regardless of the height (referred to as a vertical part) 5 and a part where the diameter changes from the vertical part up and down (referred to as an inclined part). 6 and 7.

  2A is a front cross-sectional view of a knotted wall pile that is an object of calculation of the pulling resistance force, and FIG. 2B is a side cross-sectional view. As shown in the figure, a wall pile 11 with a knot has a wall-like wall pile main body 12, one or more node portions 3, and an expanded bottom portion 4 project from the wall pile main body 12. The upper part is connected to the building's underground structure (not shown). As in the case of the round pile with a knot, the node 3 and the expanded bottom 4 correspond to the expanded diameter portion, and the expanded diameter portion is a portion where the pile diameter is constant regardless of the height (referred to as a vertical portion) ) 5 and portions (referred to as inclined portions) 6 and 7 whose diameters change from the vertical portion 5 upward and downward.

  The calculation method of the pulling resistance force of the knotted pile according to this embodiment is to calculate the pulling resistance force on the upper side of the enlarged diameter portion with higher accuracy, as will be described below. A similar principle can be used. Therefore, hereinafter, a circular pile with a knot will be described as an example.

The inventors assumed that the load acting on the knot pile 1 from the ground will be described below, and calculated the pulling resistance of the knot pile 1.
FIG. 3 is a schematic diagram showing a distribution of forces acting around the node 3 and the widened portion 4 when a pulling force is applied to the knot pile 1 assumed by the inventors. As shown in the figure, when a pulling force is applied to the knot pile 1, the supporting pressure is applied to the inclined surface 8 above the node 3 and the expanded bottom 4 from the surrounding ground in the direction opposite to the pulling force (that is, vertically downward). Works. Further, a circumferential frictional force acts on the vertical portion 5 in a direction opposite to the pulling force due to the frictional force between the vertical portion 5 and the ground surrounding the knot pile 1. In the lower inclined portion 7, the pulling-out force acts in the direction in which the ground and the lower inclined surface 9 are separated from each other, so that the pull-out resistance force does not act.

なお、式（５）における低減係数β_ｉは、安全性を確保するための低減係数であり、後述する実験結果も踏まえ、０．８５又はそれに近い値（０．８〜０．９程度）とした。 Here, as shown in FIG. 3, since the support pressure acts on the vertical projected area of the upper inclined surface 8 in the vertical direction, the pulling resistance force borne by the upper inclined portion 6 is the vertical component of the support pressure. And the product of the vertical projection area of the upper inclined surface 8. Therefore, the number of the enlarged diameter portions is N, the horizontal projected area of the inclined surface 8 on the upper side of the i-th enlarged diameter portion is A _vi [m ² ], and the ground surface near the inclined surface 8 on the upper side of the i-th enlarged diameter portion is Assuming that the ultimate support pressure degree is p _vi [kN / m ² ], the vertical component of the ultimate support pressure of the inclined surface 8 on the upper side of the i-th enlarged diameter portion is p _vi A _vi [kN]. For this reason, the total T of the ultimate pulling resistance force borne by the upper inclined surface 8 is expressed by the following equation (5).

In addition, the reduction coefficient β _i in the equation (5) is a reduction coefficient for ensuring safety, and based on the experimental results described later, it is 0.85 or a value close thereto (about 0.8 to 0.9). did.

Here, in order to calculate the ultimate pull-out resistance force borne by the upper inclined surface 8 using the equation (5), the value of the ultimate support pressure degree p _vi is required. A method of calculating this value Has not been established so far. In view of the fact that, when designing the foundation structure, the inventors usually examine the N value of the land, the uniaxial compressive strength of the soil, etc. in advance by conducting ground surveys, etc. It was decided to calculate the ultimate support pressure p _vi from values such as N value and uniaxial compressive strength obtained by the ground survey.

Specifically, as a method for calculating the ultimate support pressure degree p _vi , the inventors set the N value shown in FIG. 4 or the undrained shear strength and the ultimate support for the case where the ground is sandy soil and viscous soil. A relational expression with the pressure degree p _vi is proposed. N in the figure indicates the average N values of the ground in the vicinity of the upper inclined surface, C _u denotes the average undrained shear strength of the soil in the vicinity of the upper inclined surface. The undrained shear strength is ½ of the uniaxial compressive strength of the soil. As shown in the figure, the limit degree of pressure p _vi is 150 N for sandy soil and 6 _Cu for viscous soil, and the upper limit is 7500 [kN / m for sandy and viscous soil. ² ].

Hereinafter, the value in each case will be described.
First, as shown in FIG. 4, the ultimate bearing pressure degree p _vi in the ground of sandy soil is set to 150 N [kN / m ² ], and this value is determined as follows.
“Ministry of Land, Infrastructure, Transport and Tourism Notification No. 1113” describes the following equation (6) as the allowable stress level q _p of the ground at the tip of the foundation pile. Note that N in the formula is an average N value near the ground near the tip of the foundation pile.
q _p = 150 N / 3 (6)

Here, q _p represents the ultimate bearing strength that the ground can withstand when the indentation force acts on the foundation pile, and p _vi in equation (5) is the maximum against the compressive force of the ground when the pulling force acts on the foundation pile. Represents the degree of compressive stress. Although p _vi and q _p are different in the state of the force acting on the pile, that is, pushing and pulling out the pile, this value can be applied because the ultimate support force level of the ground does not depend on the direction of action of the force.

In Equation (6), 150N is the ultimate support pressure, and 150N is divided by 3, which is a so-called safety factor. In the equation (6), the ultimate support pressure degree p _vi of the sandy soil in the present embodiment is determined to use 150 N as a value without applying a safety factor.

In addition, as shown in FIG. 4, the ultimate bearing pressure p _vi in the viscous soil was set to 6 C _u [kN / m ² ], but this value was determined as follows.
Japanese architecture "building foundation structure design guidelines 2001 revision" of the Society of Author (hereinafter, architecture called Society of design guidelines) as the ultimate tip support force of q _p of the pile in viscous soil, have been described following equation.
q _p = 6C _u (7)

Here, q _p indicates the ultimate bearing strength that the ground can withstand when the indentation force acts on the foundation pile, so that the formula ( As p _vi of 5), the extreme tip supporting force degree q _p of Equation (7) can be used.

In addition, the maximum value of the ultimate support pressure p _vi is 7500 [kN / m ² ], but this value is determined as follows. The Ministry of Land, Infrastructure, Transport and Tourism notice states that the maximum N value is 60 (that is, the maximum value of the ultimate support pressure is 150 × 60 = 9000 [kN / m ² ]). 7500 [kN / m ² ]. Here, 7500 [kN / m ² ], which is a value on the safe side of both and widely used by those skilled in the art, is applied.

By substituting the ultimate support pressure degree p _vi obtained by the above method into the equation (5), the pulling resistance force borne by the upper inclined surface can be calculated. For this reason, the ultimate pull-out of the knot pile is calculated by summing the pull-out resistance force borne by the calculated inclined surface on the upper side of the enlarged diameter portion and the pull-out resistance force borne by the vertical portion of the enlarged diameter portion and the pile shaft portion The resistance force can be calculated.

For example, in the Architectural Institute guidelines, as the value of the limit circumferential frictional force, τ _s = 3.3 N (upper limit N = 50) for sandy soil, τ _s = C _u (upper limit C _u = 100 [kN / m ² ]). Therefore, the average value of N pile circumferential surface ground in sandy soil to N, in the cohesive soil substitutes average undrained shear strength of pile circumferential surface ground to C _u, pile shaft portion and enlarged diameter sections with piles By applying the peripheral area of the vertical part of the part, it is possible to calculate the pull-out resistance of the pile shaft part of the knotted pile and the vertical part of the enlarged diameter part. For this reason, the sum of the pullout resistance force of the shaft portion of the jointed pile and the vertical portion of the enlarged diameter portion and the sum of the pullout resistance force of the upper inclined surface is used as the pullout resistance force of the entire jointed pile. Thus, a more accurate pulling resistance can be calculated.

  In addition, although this embodiment demonstrated the case where extraction force acts on a knot pile, the case where pushing force acts on a knot pile can also be considered similarly. FIG. 5 is a schematic diagram showing the distribution of forces acting around the node 3 and the widened portion 4 when a pushing force is applied to the knot pile 1 assumed by the inventors. As shown in the figure, when a pushing force acts on the knot pile 1, the bearing pressure is applied to the inclined surface 9 below the node 3 and the expanded bottom 4 from the surrounding ground in a direction opposite to the pushing force (that is, vertically upward). Works. Further, a circumferential frictional force acts on the vertical portion 5 in a direction opposite to the pushing force due to a frictional force between the vertical portion 5 and the ground surrounding the knotted pile 1. In addition, in the upper inclined portion 6, the pushing force acts in the direction in which the ground and the upper inclined surface 8 are separated from each other, and therefore, the pushing resistance force does not act.

Therefore, the number of the enlarged diameter portions is N, the horizontal projected area of the inclined surface 8 on the upper side of the i-th enlarged diameter portion is A ′ _vi [m ² ], and the ground near the inclined surface 8 on the upper side of the i-th enlarged diameter portion. If the ultimate support pressure degree is p ′ _vi [kN / m ² ], the vertical component of the ultimate support pressure of the inclined surface 8 on the upper side of the i-th enlarged diameter portion is p ′ _vi A ′ _vi [kN]. For this reason, the total pulling resistance T ′ borne by the upper inclined surface 8 is expressed by the following equation (8).

Here, β _i and p _vi in the method of calculating the pulling resistance force can be used as β ′ _i and p ′ _vi in the equation (8).
In addition, when calculating the pullout resistance force, the bottom support of the knot pile did not need to consider the ground support force at the bottom, because the pullout force acts in the direction away from the ground when receiving the pullout force. When calculating the indentation force, the resistance force borne by the bottom of the knotted pile must also be considered.

  According to the calculation method of the pulling resistance force of the knotted pile of this embodiment, since the calculation is performed using the vertical projection area of the inclined surface on the upper side of the enlarged diameter portion, the difference between the diameters of the enlarged diameter portion and the pile shaft portion. Can be reflected in the magnitude of the pull-out resistance force, so that the pull-out resistance force of the enlarged diameter portion can be calculated more accurately. For this reason, it is possible to reduce cost reduction and improve safety by reducing excessive design due to underestimation of the pulling resistance and reducing safety due to overestimation of the pulling resistance.

In addition, by using the relationship between the N value and the uniaxial compressive strength of the soil and the ultimate bearing pressure degree p _vi shown in FIG. 4, the ultimate bearing pressure degree is obtained from the N value and the undrained shear strength obtained by the normal ground survey. p _vi can be determined. Thereby, it is possible to easily calculate the pulling resistance, and it is possible to reduce the cost and the construction period.
Moreover, although this embodiment demonstrated the case where the pulling resistance force of a round pile with a knot pile was calculated, the principle of the calculation method of the pulling resistance force of this invention is applied to a knot pile similarly to a knot wall pile. can do.

Here, since the validity of the calculation method of the drawing resistance force of this embodiment was examined using a full-sized knotted wall pile, it demonstrates below.
FIG. 5 is a diagram showing a nodal pile as a test body used in this experiment, and the soil quality and N value of the ground in which the nodal pile is embedded. As shown in the figure, this experiment used a knotted wall pile provided with a diameter-expanded portion at the middle and lower end of the wall pile as a test body. The ground in which the experiment was conducted consists of a topsoil layer near the ground surface, a Dotan layer located under the topsoil layer, and a sand layer located under the Dotan layer. The Dotan Formation is clayey ground, and its N value is 50N or more. The knotted wall pile is designed so that the lower end reaches the Dotan Formation, and the node portion and the expanded bottom portion are located in the Dotan Formation.

  FIG. 6 shows a drawing resistance force (hereinafter referred to as a calculated value) obtained by the above-described calculation method of the drawing resistance force at the node portion and the enlarged diameter portion, and a drawing resistance force (hereinafter referred to as a calculated value) obtained by this experiment. Is a table comparing experimental values). As shown in the table, the calculated value and the experimental value are very close, and the calculated value is lower than the experimental value. As described above, it has been confirmed that the above-described calculation method of the drawing resistance force can accurately evaluate the drawing resistance force of the enlarged diameter portion on the safety side.

Further, FIG. 7 is a graph showing the relationship between the degree of bearing pressure acting on the node and the widened portion obtained by this experiment and the vertical displacement. As shown in the figure, as the vertical displacement increases, the degree of support pressure acting on the enlarged diameter portion increases. However, as the vertical displacement increases, the rate of increase decreases, and the maximum value is about 7500 [kN / m ² ] at the node portion, and the maximum value is about 13000 [kN / m ² ] at the enlarged diameter portion. Become. The difference in the bearing pressure level is considered to be because the angle of the inclined surface of the enlarged diameter part is different from the vertical direction. In both cases, the maximum value of the bearing pressure level assumed above is used. The value exceeded (7500 [kN / m ² ]), and its validity was also confirmed.

It is sectional drawing of the round pile with a node used as the object of calculation of drawing resistance. (A) is front sectional drawing of the knotted wall pile used as the object of calculation of drawing-out resistance, (B) is side sectional drawing. It is the schematic diagram which showed the force which acts on a pile when drawing-out force acts on a pile with a node. Is a table showing the relationship between the N value or undrained shear strength C _u and ultimate bearing capacity force of p _vi and values. It is the schematic diagram which showed the force which acts on a pile when pushing force acts on a pile with a node. It is a figure which shows the knot pile designed using the design method using the calculation method of the drawing-out resistance of the enlarged diameter part in a knot pile. It is the table | surface which compared the calculated value and the experimental value. It is a graph which shows the relationship between the bearing pressure degree which acts on a node part and a base expansion part, and vertical displacement.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Pile with a joint 2 Pile shaft part 3 Node part 4 Expanded bottom part 5 Vertical part 6 Upper inclined part 7 Lower inclined part 8 Upper inclined surface 9 Lower inclined surface
11 Knotted wall pile 12 Wall pile body

Claims (16)

It is a method of calculating the pulling resistance force of a pile with a knot having an enlarged diameter part including an inclined surface inclined so that the diameter increases toward the lower side,
The ultimate pulling resistance that the inclined surface bears,
A method for calculating the pulling resistance force of a knotted pile, wherein the calculation is based on the product of the horizontal projected area of the inclined surface and the vertical component of the ultimate bearing pressure of the ground near the inclined surface. It is a method for calculating the pulling resistance force of a knotted pile having a plurality of enlarged diameter parts including an inclined surface that is inclined so that its diameter increases toward the lower side,
The number of the enlarged diameter portions is N, the horizontal projected area of the inclined surface of the i-th enlarged diameter portion is A _vi [m ² ], and the ultimate bearing pressure degree of the ground near the inclined surface of the i-th enlarged diameter portion is p _vi [ kN / m ² ], when the reduction coefficient of the inclined surface of the i-th enlarged portion is β _i ,
A calculation method of pulling resistance force of a knotted pile characterized by calculating based on a sum T [kN] of ultimate pulling resistance force of the inclined surface of each enlarged diameter portion obtained by the following formula (1).

The method of calculating the pulling resistance force of a knotted pile according to claim 2, wherein the reduction coefficient β _i is set to a value of 0.8 to 0.9. A method for calculating the pullout resistance of the knotted pile according to claim 2 or 3,
When the average N value in the vicinity of the inclined surface of the enlarged diameter portion embedded in sandy soil is N,
Calculated by Equation (2) below the ultimate bearing capacity power level _{p vi} as the value of the ultimate Bearing force of _{p vi} in equation (1),
If the value of p _vi obtained by Equation (2) is less than 7500 [kN / m ² ], the value of p _vi obtained above is
If the value of p _vi obtained by the equation (2) is 7500 [kN / m ² ] or more, 7500 [kN / m ² ] is used.
p _vi = 150N (2) It is the calculation method of the drawing-out resistance of the knot pile according to any one of claims 2 to 4,
When the average of the undrained shear strength near the inclined surface of the i-th enlarged diameter portion which is embedded in the cohesive soil was C _U,
As the value of the ultimate support pressure p _vi in the formula (1),
The ultimate bearing pressure degree p _vi is obtained by the following equation (3),
When the ultimate support pressure degree p _vi calculated by the expression (3) is less than 7500 [kN / m ² ], the calculated ultimate support pressure degree is
When the ultimate bearing pressure p _vi calculated by the equation (3) is 7500 [kN / m ² ] or more, 7500 [kN / m ² ] is used. Method of calculation.
p _vi = 6C _U (3) It is a method for calculating the indentation resistance force of a knotted pile having an enlarged diameter portion including an inclined surface that is inclined so that the diameter increases toward the upper side,
The ultimate indentation resistance force borne by the inclined surface,
A method for calculating the indentation resistance force of a knotted pile, wherein the calculation is based on a product of a horizontal projected area of the inclined surface and a vertical component of the ultimate bearing pressure degree of the ground near the inclined surface. It is a method of calculating the indentation resistance force of a pile with a knot having a plurality of enlarged diameter parts including an inclined surface inclined so that the diameter increases toward the upper side,
The number of the expanded portions is N, the horizontal projected area of the inclined surface of the i-th expanded portion is A ′ _vi [m ² ], and the ultimate bearing pressure degree of the ground near the inclined surface of the i-th expanded portion is p ′. _vi [kN / m ² ], when the reduction coefficient of the inclined surface of the i-th expanded portion is β ′ _i ,
A method for calculating the indentation resistance force of a knotted pile, wherein the calculation is based on the sum T ′ [kN] of the ultimate indentation resistance force of the inclined surface of each enlarged diameter portion obtained by the following formula (4).

  The method for calculating the pulling resistance force of the knotted pile according to any one of claims 1 to 5, wherein the knotted pile is a rounded pile with a knot.   The method for calculating the indentation resistance force of a knotted pile according to claim 6 or 7, wherein the knotted pile is a rounded pile with a knot.   The method for calculating the pulling resistance force of a knotted pile according to any one of claims 1 to 5, wherein the knotted pile is a knotted wall pile.   The method for calculating the indentation resistance force of a knotted pile according to claim 6 or 7, wherein the knotted pile is a knotted wall pile.   It is a design method of the knot pile which has two or more enlarged diameter parts including the inclined surface inclined so that a diameter may become large in the lower side, Comprising: Pulling out the knot pile according to any one of claims 1 to 5 A design method for a knot pile characterized by designing the drawing resistance calculated by the calculation method of the resistance to be equal to or greater than a predetermined reference resistance.   It is a design method of the knot pile which has two or more enlarged diameter parts including the inclined surface inclined so that a diameter may become large toward the upper side, Comprising: It calculates with the calculation method of the indentation resistance force of the knot pile according to claim 6 or 7 A method for designing a pile with knots, wherein the designed indentation resistance is designed to be equal to or greater than a predetermined reference resistance.   The method for designing a knotted pile according to claim 12 or 13, wherein the knotted pile is a rounded pile with a knot.   The method for designing a knotted pile according to claim 12 or 13, wherein the knotted pile is a knotted wall pile. A knotted pile designed by the knotted pile design method according to any one of claims 12 to 15.

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