JP5798376B2 - Method for determining structural specifications of embedded piles - Google Patents

Method for determining structural specifications of embedded piles Download PDF

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JP5798376B2
JP5798376B2 JP2011116008A JP2011116008A JP5798376B2 JP 5798376 B2 JP5798376 B2 JP 5798376B2 JP 2011116008 A JP2011116008 A JP 2011116008A JP 2011116008 A JP2011116008 A JP 2011116008A JP 5798376 B2 JP5798376 B2 JP 5798376B2
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embedded
bearing
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JP2012241500A (en
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広人 今
広人 今
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Japan Pile Corp
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Description

この発明は、埋込み杭の構造仕様決定方法に関し、より詳細には先端部に節部などの突起部を有する杭体と、その先端部が挿入される根固め部の仕様を決定する方法に関する。   The present invention relates to a method for determining the structural specifications of an embedded pile, and more particularly to a method of determining the specifications of a pile body having a protrusion such as a node at the tip and a rooting portion into which the tip is inserted.

杭孔の底部にソイルセメントによる根固め部を形成して、この杭孔に既製杭、例えば下端部に節部を有する既製杭を節部が根固め部に入り込むように埋設する埋込み杭工法が知られている。   There is an embedded pile construction method in which a soil-solidified part is formed at the bottom of the pile hole, and a prefabricated pile, such as a pre-made pile having a node at the lower end, is embedded in the pile hole so that the node enters the rooted part. Are known.

このような埋込み杭工法において、既製杭がこれに加わる荷重によって沈下を生じないようにするためには、根固め部での地盤支持力が設計荷重以上で、かつ既製杭と根固め部との一体性が確保されていることが必要である。   In such an embedded pile construction method, in order to prevent the ready-made pile from subsidizing due to the load applied to it, the ground supporting force at the root consolidation part is greater than the design load, and the It is necessary to ensure unity.

上記のような要求を満たす杭体及び根固め部仕様とするために、従来は、根固め部径及び節部径を設定し、FEM解析結果から必要なソイルセメント強度を決定するという単純な手法がとられている。   In order to make the pile body and the root consolidation part specification satisfying the above requirements, conventionally, a simple method of setting the root consolidation part diameter and the nodal part diameter and determining the required soil cement strength from the FEM analysis results. Has been taken.

節杭の場合、これと根固め部との一体性が確保されていれば、節部に支圧力が作用し、また杭先端部を根固め部底面から上方に離隔させた場合、その離隔高さに応じて杭先端部の支圧力が増大することが判明している。   In the case of joint piles, if the integrity of the piles is secured, the support pressure acts on the joints, and if the pile tip is separated upward from the bottom of the piles, the separation height It has been found that the bearing pressure at the pile tip increases accordingly.

しかし、従来の手法はこれらの作用力を構造仕様の決定に何ら加味することなくなされているため、ソイルセメントの強度が過度に大きくなったりして不経済であるという問題がある。   However, since the conventional technique is made without taking these acting forces into consideration in determining the structural specifications, there is a problem that the strength of the soil cement becomes excessively high and is uneconomical.

なし   None

この発明は上記のような技術的背景に基づいてなされたものであって、次の目的を達成するものである。
この発明の目的は、既製杭と根固め部との一体性が確保されているという条件の下では、既製杭に有利な支圧力が作用していることを考慮し、それによって経済的な杭体構造及び根固め部構造とすることができる方法を提供することにある。
The present invention has been made based on the technical background as described above, and achieves the following object.
The object of the present invention is to consider that an advantageous bearing pressure is acting on the ready-made pile under the condition that the integrity of the ready-made pile and the root solidified part is ensured, and thereby the economical pile. It is providing the method which can be set as a body structure and a root structure part structure.

<この発明の理論的背景>
図1は、杭孔4の底部に形成されたソイルセメントによる根固め部2と、この根固め部2に節部3を有する下端部が入り込むように杭孔に埋設された節杭1とを示している。根固め部2に配置された節杭1の下端部と根固め部2との一体性が確保されていると仮定すると、節杭1が荷重Pを支持し鉛直方向に変位を生じないためには、根固め部2に地盤から作用する支持力が荷重P以上であることが条件となる。荷重Pに対抗する支持力は、根固め部2の底面に作用する先端支持力Rp と根固め部2の周面に作用する摩擦力Rf の和であり、支持条件は、
P≦Rp+Rf・・・(1)
で示される。
<Theoretical background of the present invention>
FIG. 1 shows a root cemented portion 2 made of soil cement formed at the bottom of a pile hole 4, and a node pile 1 embedded in the pile hole 4 so that a lower end portion having a node portion 3 enters the root consolidated portion 2. Is shown. Assuming that the integrity of the bottom end of the joint pile 1 arranged in the root consolidation part 2 and the root consolidation part 2 is secured, the joint pile 1 supports the load P and does not cause displacement in the vertical direction. The condition is that the supporting force acting on the root hardening part 2 from the ground is equal to or greater than the load P. The supporting force that opposes the load P is the sum of the tip supporting force Rp that acts on the bottom surface of the root consolidation portion 2 and the friction force Rf that acts on the peripheral surface of the root consolidation portion 2.
P ≦ Rp + Rf (1)
Indicated by

ここで、図2に示すように、節杭1に着目すると、節杭1は荷重Pを受けることによって、これに対抗する力として節部3と杭先端に支圧力が作用する。したがって、節杭1の先端部と根固め部との一体性が確保されるという上記仮定を満足して、節杭1が鉛直方向に変位を生じないためには、これら支圧力の和が荷重P以上であることが条件となる。その条件は個々の節部3に作用する支圧力をR1 、節部の数をn、杭先端支圧力をR2 とすると、
P≦n・R1 +R2・・・(2)
で示される。
Here, as shown in FIG. 2, when paying attention to the joint pile 1, when the joint pile 1 receives the load P, a supporting pressure acts on the joint portion 3 and the tip of the pile as a force against this. Therefore, in order to satisfy the above assumption that the integrity of the tip portion and the rooted portion of the joint pile 1 is ensured and the joint pile 1 is not displaced in the vertical direction, the sum of these support pressures is the load. It is a condition that it is P or more. The condition is that R1 is the bearing pressure acting on each node 3, n is the number of nodes, and R2 is the pile tip bearing pressure.
P ≦ n · R1 + R2 (2)
Indicated by

節部支圧力R1 を決定するパラメータは、節部径、軸部径、根固め部材料(例えばソイルセメント)によって決まる根固め部強度などであり、節部全体での支圧力を決定するパラメータは節部の数nである。また、杭先端支圧力R2 を決定するパラメータは、軸部径、根固め部2の底面からの杭先端の離隔高さ(その意義については後述する)などである。したがって、式(1)(2)を満足するという条件の下、上記各パラメータを変化させることによって、最適な杭体及び根固め部の構造仕様を選択することが可能となる。   The parameters that determine the nodal support pressure R1 are the nodal diameter, shaft diameter, root consolidation strength determined by the root material (eg, soil cement), and the parameters that determine the overall support pressure are The number of nodes is n. The parameters that determine the pile tip support pressure R2 are the shaft diameter, the separation height of the pile tip from the bottom surface of the root consolidation portion 2 (the significance of which will be described later), and the like. Therefore, it is possible to select the optimum structural specifications of the pile body and the root-solidifying portion by changing each of the above parameters under the condition that the expressions (1) and (2) are satisfied.

この発明は、上記のような知見に基づいてなされたものであって、次のような手段を採用している。
すなわち、この発明は、底部にソイルセメントによる根固め部が形成された杭孔に、下端部に節部を有する既製杭を前記節部が前記根固め部に入り込むように埋設してなる埋込み杭の構造仕様決定方法であって、次式(1)(2)、
P≦Rp+Rf ・・・(1)
P≦n・R1+R2 ・・・(2)
ただし、P:設計荷重、Rp:根固め部底面に作用する先端支持力、Rf:根固め部周面 に作用する摩擦力、n:節部の数、R1:節部1個に作用する支圧力、R2:杭先端支圧
を満足するように、杭体及び根固め部の仕様を決定し、前記節部1個の支圧力R1 については次式(3)
R1=α・qu×At ・・・(3)
ただし、α:支圧強度係数(α=1.0 〜2.0)、qu:ソイルセメント強度、At:節部支 圧面積
から算出することを特徴とする埋込み杭の構造仕様決定方法にある。
The present invention has been made on the basis of the above knowledge, and employs the following means.
That is, the present invention is to Kuiana roots hardened portions by soil cement is formed in the bottom, the buried piles the knuckles prefabricated pile having knuckles on the lower end is buried so as to enter the root hardened portion The structural specification determination method of the following formulas (1) (2),
P ≦ Rp + Rf (1)
P ≦ n · R1 + R2 (2)
Where P: design load, Rp: tip support force acting on the bottom of the root consolidation part, Rf: frictional force acting on the periphery of the root consolidation part , n: number of nodes, R1: support acting on one node pressure, R2: to satisfy the pile tip Bearing force <br/>, to determine the specifications of the pile body and root consolidated unit, the following equation for the knuckles one Bearing force R1 (3)
R1 = α · qu × At (3)
However, alpha: bearing capacity coefficient (α = 1.0 ~2.0), qu : soil cement strength, At: knurl supporting pressure area
It is in the structural specification determination method of the embedded pile characterized by calculating from .

より具体的には、上記式(2)を満足するように、杭体の根固め部底面からの離隔高さ、節部径及び杭軸部径、節部の数及びソイルセメント強度を設定することを特徴とする。 More specifically, to satisfy the above formula (2), set apart height from the root firm bottom face of the pile body, knurl diameter and Kuijiku portion diameter, the number and soil cement strength knuckles It is characterized by that.

この発明によれば、既製杭と根固め部との一体性が確保されているという条件の下では、既製杭に有利な支圧力が作用していることを考慮して、杭体構造及び根固め部構造を決定するので、根固め部強度などを、荷重を支持するのに過不足ないものとすることができ、経済的な設計をすることができる。   According to the present invention, under the condition that the integrity of the ready-made pile and the root solidified portion is ensured, the pile structure and the root are considered in consideration of the advantageous support pressure acting on the ready-made pile. Since the solidified portion structure is determined, the strength of the solidified portion and the like can be set to be sufficient to support the load, and an economical design can be achieved.

杭体と根固め部が一体となっている場合に根固め部に作用する力を示す図である。It is a figure which shows the force which acts on a root consolidation part when a pile body and a root consolidation part are united. 杭体に作用する支圧力を示す図である。It is a figure which shows the support pressure which acts on a pile body. 杭体の諸元を示す図である。It is a figure which shows the item of a pile body. 杭体及び根固め部構造仕様の決定方法の手順を示すフローチャートである。It is a flowchart which shows the procedure of the determination method of a pile body and a solidified part structure specification. 図4に引き続くフローチャートである。It is a flowchart following FIG. ソイルセメント強度と支圧強度との関係を示すグラフである。It is a graph which shows the relationship between soil cement strength and bearing strength. 杭先端離隔高さと、それによる支圧力の利得係数との関係を示すグラフである。It is a graph which shows the relationship between pile tip separation height and the gain coefficient of the bearing pressure by it.

図3は、この発明に基づき決定する杭体及び根固め部の諸元を示している。De は根固め部径、Hは根固め部高さ、H1 は杭先端部の根固め部底面からの離隔高さ、Dn は節部径、Dp は軸部径である。以下、杭体及び根固め部の構造仕様を決定する手順を図4及び図5に示すフローチャートを参照しながら説明する。   FIG. 3 shows the specifications of the pile body and the root-solidified portion determined based on the present invention. De is the root consolidation part diameter, H is the root consolidation part height, H1 is the height of the pile tip from the bottom of the root consolidation part, Dn is the node part diameter, and Dp is the shaft part diameter. Hereinafter, the procedure for determining the structural specifications of the pile body and the rooting portion will be described with reference to the flowcharts shown in FIGS. 4 and 5.

1.設計荷重Pの決定(ステップS1)
設計荷重Pは、根固め部内の節杭1本で支持させる荷重(KN)である。
2.施工方法の決定(ステップS2)
埋込み杭工法には、既製杭工法、プレボーリング工法、中掘工法などがあり、いずれかを選択する。
1. Determination of design load P (step S1)
The design load P is a load (KN) supported by one node pile in the root consolidation part.
2. Determination of construction method (step S2)
The embedded pile construction method includes a ready-made pile construction method, a pre-boring construction method, and a medium digging construction method, and one of them is selected.

3.地盤の支持力度qd の算出(ステップS3)
支持力度qd (図1,2参照)は根固め部2の先端地盤が受け持つ耐力度であり、地盤のN値及び土質から算出する。例えば、道路橋示方書ではプレボーリング工法の場合、砂地盤:qd =150N(≦7500kN/m2)、礫地盤:qd =200N(≦10000kN/m2) と規定されている。
4.根固め部高さH、杭先端離隔高さH1 の設定(ステップS4)
初期設定は例えばH=2.0m 、H1=0m とする。
3. Calculation of ground bearing strength qd (step S3)
The bearing strength qd (see FIGS. 1 and 2) is a bearing strength that the tip ground of the root consolidation part 2 takes on and is calculated from the N value of the ground and the soil quality. For example, in the pre-boring method, the road bridge specifications specify sand ground: qd = 150N (≦ 7500kN / m 2 ) and gravel ground: qd = 200N (≦ 10000kN / m 2 ).
4). Setting of height of root consolidation part H and pile tip separation height H1 (step S4)
For example, the initial settings are H = 2.0 m and H1 = 0 m.

5.根固め部径De の算出(ステップS5)
根固め部径De は、上記(1)式より算出する。(1)式において周面摩擦力Rf は、Rf=f・U・H (f:周面地盤が受け持つ摩擦力度、U:根固め部の周長、H:根固め部の高さ)で示される。周面摩擦力度fは根固め部2の周面が受け持つ摩擦力の度合いであり、例えば道路橋示方書ではプレボーリング工法の場合、砂地盤:f=5N(≦150kN/m2)、粘土地盤:f=10N(≦100kN/m2) と規定されている。しかし、周面摩擦力Rf は先端支持力Rp に比べて極めて小さく、また安全側をみることとしてゼロとする。したがって、根固め部径De は次式により算出される。
P=Rp +Rf
=Rp +0
=qd・De2・π/4
5. Calculation of root diameter De (Step S5)
The root diameter De is calculated from the above equation (1). In formula (1), the peripheral frictional force Rf is indicated by Rf = f · U · H (f: Friction force of the peripheral surface, U: Perimeter of root consolidation, H: Height of root consolidation) It is. The skin friction of f is a degree of frictional force responsible circumferential surface of the root hardened portion 2, if the pre-boring method is, for example, specifications for highway bridges, sand soil: f = 5N (≦ 150kN / m 2), Clay : F = 10 N (≦ 100 kN / m 2 ) However, the peripheral friction force Rf is extremely smaller than the tip support force Rp and is zero as viewed from the safe side. Accordingly, the root diameter De is calculated by the following equation.
P = Rp + Rf
= Rp +0
= Qd · De 2 · π / 4

6.節部径Dn 、軸部径Dp の設定(ステップS6)
節部径Dn は杭を根固め部に挿入するために、根固め部径De に対して例えば50mmの余裕をとりDe>Dn+50 とする。通常、既製杭は規格化されており、したがって規格品のうち節部径Dn がある値のものを選択すると、軸部径Dp も自ずと決まる。
7.節部支圧面積At の算出(ステップS7)
節部支圧面積At は、軸部から突出している節部の面積である。節部径Dn 、軸部径Dp が設定されていることから、節部支圧面積At は、次式により算出される。
At =(Dn2 − Dp2)・π/4
6). Setting of node diameter Dn and shaft diameter Dp (step S6)
The node diameter Dn is set such that De> Dn + 50 with a margin of 50 mm, for example, with respect to the root diameter De in order to insert the pile into the root consolidation part. Normally, ready-made piles are standardized, and therefore, when a standard product with a value having a node diameter Dn is selected, the shaft diameter Dp is also determined by itself.
7). Calculation of joint bearing area At (Step S7)
The nodal bearing bearing area At is an area of the nodal portion protruding from the shaft portion. Since the node diameter Dn and the shaft diameter Dp are set, the node bearing area At is calculated by the following equation.
At = (Dn 2 −Dp 2 ) · π / 4

8.ソイルセメント強度qu の設定(ステップS8)
ソイルセメント強度qu は、5 〜30N/mm2 の範囲内で適宜の値を選択する。ただし、杭先端離隔高さH1 >0 とした場合は、地盤の支持力度qd ≦ソイルセメント強度qu とする。
9.ソイルセメント強度qu から支圧強度の算出(ステップS9)
ここでいう支圧強度とは、節部のみで荷重を支持するとした場合のソイルセメントの強度のことである。この発明の発明者らは、根固め部内で杭先端には支圧力が作用せずに、節部のみに支圧力が作用するようにした装置を作り、杭に荷重を加えて杭の支持力を測定したところ、ソイルセメント強度qu と支圧強度との間には図6に示すような関係があることが分かった。すなわち、支圧強度=α・qu (α:支圧強度係数、α=1.0 〜2.0)の関係にあって、支圧強度をソイルセメント強度qu よりも大きくとれる。そこで、αを1.0 〜2.0 の範囲から適宜選択して支圧強度を算出する。
8). Setting of soil cement strength qu (Step S8)
As the soil cement strength qu, an appropriate value is selected within the range of 5 to 30 N / mm 2 . However, if the pile tip separation height H1> 0, the ground support strength qd ≦ soil cement strength qu.
9. Calculation of bearing strength from soil cement strength qu (Step S9)
The bearing strength here refers to the strength of the soil cement when the load is supported only by the joints. The inventors of the present invention have made a device in which the bearing pressure does not act on the tip of the pile within the rooting portion, but the bearing pressure acts only on the node, and the pile is supported by applying a load to the pile. Was measured, and it was found that there was a relationship as shown in FIG. 6 between the soil cement strength qu and the bearing strength. That is, the bearing strength is α · qu (α: bearing strength coefficient, α = 1.0 to 2.0), and the bearing strength can be greater than the soil cement strength qu. Therefore, α is appropriately selected from the range of 1.0 to 2.0 to calculate the bearing strength.

10.節部1個の支圧力R1 の算出(ステップS10)
節部1個の支圧力R1 はステップS7 で算出した支圧面積At と、ステップS9 で算出した支圧強度を用い、支圧力R1=支圧強度×支圧面積At の式から求めることができる。
11.節部の数の設定(ステップS11)
初期設定は、例えばn=2 とする。
10. Calculation of bearing pressure R1 for one joint (step S10)
The bearing pressure R1 of one node can be obtained from the formula of bearing pressure R1 = bearing strength × bearing area At using the bearing area At calculated in step S7 and the bearing strength calculated in step S9. .
11. Set the number of nodes (Step S11)
The initial setting is, for example, n = 2.

12.節部支圧力及び杭先端支圧力の算出(ステップS12)
節部支圧力は個々の節部に作用する支圧力の総和であり、ステップS10で算出した節部支圧力R1にnを乗じて求めることができる。一方、杭先端支圧力R2 については、この発明の発明者らの実験によれば、杭先端を根固め部底面から上方に離隔させると、ある一定高さまではそれに比例して支圧力が増大することが判明している。図7は、離隔高さH1 に対する軸部径Dp の比を横軸にとり、離隔によって得られる支圧力の増し分の割合に1を加えたものを利得係数β(≧1)とし、これを縦軸にとったグラフである。
12 Calculation of joint support pressure and pile tip support pressure (Step S12)
The nodal support pressure is the sum of the support pressures acting on the individual nodal parts, and can be obtained by multiplying the nodal support pressure R1 calculated in step S10 by n. On the other hand, with regard to the pile tip support pressure R2, according to the experiments of the inventors of the present invention, when the pile tip is separated upward from the bottom of the rooting portion, the support pressure increases in proportion to a certain height. It has been found. In FIG. 7, the ratio of the shaft diameter Dp to the separation height H1 is taken on the horizontal axis, and the gain factor β (≧ 1) is obtained by adding 1 to the ratio of the increase in the support pressure obtained by the separation, It is a graph taken on the axis.

杭先端支圧力R2 は、軸部径Dp 、地盤の支持力度qd 及びグラフに示された離隔による利得係数βを用いて、R2 =(Dp2・π/4)・qd・βより算出する。ここで、離隔高さH1 =0 のとき、すなわち杭先端を根固め部底面まで挿入したときβ=1 であり、H1 >0 のとき、すなわち杭先端を根固め部底面から離隔させたときβ>1 である。
13.杭体と根固め部との一体性が確保されているかの判定(ステップS13)
以上のようにして、節部支圧力nR1 と杭先端支圧力R2 とを算出したら、上記式(2)を満足するか否かを判断する。式(2)を満足する場合は、杭体と根固め部との一体性が確保され、したがって節部支圧力nR1 及び杭先端支圧力R2 の算出に関与する各パラメータは設定値で良いものとし、杭体及び根固め部の構造を決定する。
The pile tip support pressure R2 is calculated from R2 = (Dp 2 · π / 4) · qd · β by using the shaft diameter Dp, the bearing capacity qd of the ground and the gain coefficient β due to the separation shown in the graph. Here, when the separation height H1 = 0, that is, β = 1 when the pile tip is inserted to the bottom of the rooting portion, and when H1> 0, that is, when the pile tip is separated from the bottom of the rooting portion, β > 1.
13. Judgment of integrity of pile body and root-solidified part (step S13)
As described above, when the nodal support pressure nR1 and the pile tip support pressure R2 are calculated, it is determined whether or not the above formula (2) is satisfied. If the formula (2) is satisfied, the integrity of the pile body and the root solidified part is ensured. Therefore, the parameters related to the calculation of the nodal support pressure nR1 and the pile tip support pressure R2 should be set values. Determine the structure of the piles and roots.

他方、節部支圧力nR1 及び杭先端支圧力R2 が式(2)を満足しない場合は、ステップS4 以下を再度実行し、節部支圧力nR1 及び杭先端支圧力R2 の算出に関与する各パラメータの値を設定しなおす。設定値を変更するパラメータは、杭先端離隔高さH1 、節部径Dn 、軸部径Dp 、ソイルセメント強度qu 、節部の数nのうち少なくとも1つであれば、いずれを変更してもよい。   On the other hand, if the nodal support pressure nR1 and the pile tip support pressure R2 do not satisfy the formula (2), step S4 and subsequent steps are executed again, and each parameter involved in the calculation of the nodal support pressure nR1 and the pile tip support pressure R2 is calculated. Reset the value of. The parameter for changing the setting value is at least one of the pile tip separation height H1, the node diameter Dn, the shaft diameter Dp, the soil cement strength qu, and the number n of the nodes. Good.

この発明が適用できる杭体構造としては、突起部として節部を設ける場合、少なくとも1つあればよい。突起部は節部に限らず、軸部の周面に多数の突起を間隔を置いて環状となるように設けたものでもよい。杭体はコンクリート杭であっても鋼管杭であってもよい。根固め部構造としては、杭孔の下部を拡大して形成される拡大根固め部でも、拡大しない根固め部でもよい。根固め部材料は掘削土とセメントミルクとを混合撹拌して形成されるソイルセメントが一般的であるが、セメントモルタルなどの他の固化材単体としてもよい。   As a pile body structure to which the present invention can be applied, when a node portion is provided as a projection portion, at least one is sufficient. The protruding portion is not limited to the node portion, and a plurality of protruding portions may be provided on the peripheral surface of the shaft portion so as to be annular at intervals. The pile body may be a concrete pile or a steel pipe pile. As a root-solidification part structure, the expansion root-consolidation part formed by expanding the lower part of a pile hole, or the root-consolidation part which does not expand may be sufficient. The root hardening material is generally a soil cement formed by mixing and stirring excavated soil and cement milk, but may be another solidifying material such as cement mortar alone.

1:既製杭(節杭)
2:根固め部
3:節部
1: Ready-made pile (node pile)
2: Rooting part 3: Node part

Claims (2)

底部にソイルセメントによる根固め部が形成された杭孔に、下端部に節部を有する既製杭を前記節部が前記根固め部に入り込むように埋設してなる埋込み杭の構造仕様決定方法であって、次式(1)(2)、
P≦Rp+Rf ・・・(1)
P≦n・R1+R2 ・・・(2)
ただし、P:設計荷重、Rp:根固め部底面に作用する先端支持力、Rf:根固め部周面 に作用する摩擦力、n:節部の数、R1:節部1個に作用する支圧力、R2:杭先端支圧
を満足するように、杭体及び根固め部の仕様を決定し、前記節部1個の支圧力R1 については次式(3)
R1=α・qu×At ・・・(3)
ただし、α:支圧強度係数(α=1.0 〜2.0)、qu:ソイルセメント強度、At:節部支 圧面積
から算出することを特徴とする埋込み杭の構造仕様決定方法。
In the method of determining the structural specifications of an embedded pile in which a pile is formed with a soil cement root at the bottom and a pre-made pile having a node at the lower end is embedded so that the node enters the root consolidation And the following formulas (1), (2),
P ≦ Rp + Rf (1)
P ≦ n · R1 + R2 (2)
Where P: design load, Rp: tip support force acting on the bottom of the root consolidation part, Rf: frictional force acting on the periphery of the root consolidation part , n: number of nodes, R1: support acting on one node pressure, R2: to satisfy the pile tip Bearing force <br/>, to determine the specifications of the pile body and root consolidated unit, the following equation for the knuckles one Bearing force R1 (3)
R1 = α · qu × At (3)
However, alpha: bearing capacity coefficient (α = 1.0 ~2.0), qu : soil cement strength, At: knurl supporting pressure area
A structural specification determination method for embedded piles, characterized in that
上記式(2)を満足するように、杭体の根固め部底面からの離隔高さ、節部径及び杭軸部径、節部の数及びソイルセメント強度を設定することを特徴とする請求項1記載の埋込み杭の構造仕様決定方法。 So as to satisfy the above formula (2), claims and setting apart from the root firm bottom face of the pile body height, knurl diameter and Kuijiku portion diameter, the number and soil cement strength knuckles Item 3. A method for determining the structural specifications of an embedded pile according to item 1.
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