JP5495325B2 - Pile foundation structure, construction method of pile foundation structure and pile used for these - Google Patents

Description

  The present invention relates to a pile foundation structure capable of increasing the resistance (stability) to pulling out of the pile, a method for constructing the pile foundation structure, and a pile used for these.

  FIG. 10 schematically shows a conventional pile foundation structure of a pier. As shown in FIG. 10, the pier is driven so that foundation piles P1, P2,... Made of a plurality of steel pipes reach the support layer G1 from the bottom S1 below the water surface S into the ground G, and the foundation pile P1. , P2 is constructed by installing the superstructure U on the top.

  Here, one of the performance verification items in the design of the pier is a study on pulling out piles. That is, when a horizontal force H is generated in the horizontal load D due to an impact at the time of landing on the ship, an inertial force due to an earthquake, etc., for example, an acting force to pull out the foundation pile P1 of the pier driven into the ground G. (Drawing force) V1 and the acting force (pushing force) V2 which tries to push in the foundation pile P2 generate | occur | produce, respectively. Whether or not the pile P1 is pulled out is determined by using the peripheral friction force F between the pile P1 and the ground G and the dead weight of the pile P1 as resistance to the pulling force V1. Here, when it is determined that the pile P is pulled out, a method of increasing the circumferential friction force F by increasing the pile diameter or extending the pile length to increase the contact area between the pile P and the ground G. It is common to adopt. Or the whole structure may be reexamined greatly, such as increasing the number of piles to be laid.

  However, if the pile diameter is easily increased, the design is excessively safe with respect to other verification items (for example, the degree of stress of the pile), and the structure is often very uneconomical.

  Also, when extending the pile length, if the pile tip has already reached the support layer G1, it will penetrate deeply into the support layer G1 and load will be applied to the pile, causing damage and buckling of the pile tip. Concerned. In addition, when the support layer G1 is thin, the support layer may be punched out, and it may be impossible to obtain a predetermined support force for pushing the pile.

  The pulling force becomes a problem as shown in FIG. 10 because the horizontal force H due to the inertial force at the time of earthquake acts on the pier as shown in FIG. It is also effective to reduce the inertia force during an earthquake (horizontal force H) by reducing the weight of the cargo handling machine. However, the weight reduction of the superstructure U and the loading load D is limited because it involves an increase in cost (such as the use of lightweight concrete) and a decrease in the pier function (such as the specification down of the loading machine).

  Based on the above-mentioned present situation, the present invention increases the resistance (stability) against pulling out of the pile without relying on the expansion of the pile diameter or the increase in the buried length (ie, the peripheral frictional force between the pile and the ground). An object of the present invention is to provide a pile foundation structure that can be made, a construction method of the pile foundation structure, and a pile used for these.

  A pile foundation structure for achieving the above object is provided with a partitioning portion in a foundation pile made of a hollow tube, and the foundation pile is divided into an upper part and a lower part in the vertical direction by the partitioning part and placed in the ground. A suction force (suction) that resists the pulling force when a pulling force acts on the foundation pile by sealing at least a part of the lower part of the pile with water or water and ground material. It is characterized by producing.

  According to this pile foundation structure, a foundation pile divided into an upper part and a lower part in the partition is placed on the ground, and at least a part of the lower part of the partition is saturated with water or water and ground material and sealed. Thus, when a pulling force is applied to the foundation pile that has been laid, a suction force (suction) that resists the pulling force can be generated. For this reason, it is possible to increase the resistance (stability) to the pulling out of the pile without depending on the enlargement of the pile diameter or the increase in the buried length.

  In the pile foundation structure, it is preferable that a resistance against the pulling-out force is obtained by disposing a filling material in the upper part. By placing the filling material in the upper part of the foundation pile, it can resist the pulling force of the pile as a counter.

  Moreover, suction force (suction) can be effectively produced by making the space surrounded by the partition part and the ground surface in the foundation pile in the lower part into a negative pressure instead of the saturated state. . Moreover, the seepage flow is generated in the ground outside the foundation pile, the effective stress of the surrounding ground is increased, and it can contribute to the increase in the peripheral friction force between the pile and the ground.

  It is preferable that the foundation pile is placed on the bottom of the water and the upper water level is the same level as the external water level (no water head difference occurs).

  A method for constructing a pile foundation structure for achieving the above object is to provide a partition portion in a foundation pile made of a hollow tube, divide the foundation pile into an upper part and a lower part in the vertical direction by the partition part, and Is placed in the ground, and at least a part of the lower part is saturated with water or water and ground material, and then sealed.

  According to the construction method of this pile foundation structure, the foundation pile divided into the upper part and the lower part in the partition is placed on the ground, and at least a part of the lower part of the partition is saturated with water or water and the ground material By making it seal | tighten, when drawing-out force acts on the foundation pile placed, the suction force (suction) which resists drawing-out force can be produced. For this reason, it is possible to increase the resistance (stability) to the pulling out of the pile without depending on the enlargement of the pile diameter or the increase in the buried length.

  In the construction method of the pile foundation structure, it is preferable that the filling material is thrown into the upper part after the foundation pile is placed. Thereby, the resistance force with respect to the pulling-out force of a pile can be obtained. Thus, it can resist as a counter with respect to the drawing-out force of a pile by arrange | positioning a filling material in the upper part of a foundation pile.

  In addition, the space surrounded by the partition and the ground surface in the foundation pile at the lower part is made negative pressure instead of the saturated state, so that suction force (suction) is effective in the placed foundation pile. Can be generated automatically. Moreover, the seepage flow is generated in the ground outside the foundation pile, the effective stress of the surrounding ground is increased, and it can contribute to the increase in the peripheral friction force between the pile and the ground.

  Moreover, it is preferable that the foundation pile is placed on the bottom of the water, and the upper water level is the same level as the outside water level (no water head difference occurs).

  In order to obtain the pile foundation structure, for example, a valve is provided so as to communicate with the lower portion of the foundation pile, the valve is opened, the foundation pile is driven into the ground, and at least a part of the lower portion is provided. The pile foundation structure can be constructed by saturating the water with water or water and the ground material, then closing the valve and sealing the inside of the lower part.

  A pile for achieving the above object is a pile made of a hollow tube used in the construction method of the above-mentioned pile foundation structure or the above-mentioned pile foundation structure, wherein a partition portion is provided in the pile. .

  According to this pile, the pile divided into the upper part and the lower part in the partition part is placed on the ground, and at least a part of the lower part of the partition part is saturated with water or water and the ground material and sealed. When a pulling force is applied to the pile that has been laid, a suction force (suction) that resists the pulling force can be generated. For this reason, it is possible to increase the resistance (stability) to the pulling out of the pile without depending on the enlargement of the pile diameter or the increase in the buried length.

  According to the pile foundation structure of the present invention, the method for constructing the pile foundation structure, and the piles used for these, the piles are not relied on without increasing the pile diameter or increasing the buried length (the peripheral frictional force between the pile and the ground). It is possible to increase the resistance (stability) to the pulling out.

It is a figure showing roughly the pile foundation structure by a 1st embodiment. It is a figure which shows schematically the pile foundation structure by 2nd Embodiment. It is a figure which shows schematically the pile foundation structure by 3rd Embodiment. It is a figure which shows roughly the structure of the steel pipe pile by 4th Embodiment. It is a flowchart for demonstrating the process until the pile foundation structure of FIG. 1 is constructed | assembled using the steel pipe pile of FIG. 4, and a superstructure is installed. It is a flowchart for demonstrating the process until the pile foundation structure of FIG. 2 is constructed | assembled using the steel pipe pile of FIG. 4, and a superstructure is installed. It is a flowchart for demonstrating the process until the pile foundation structure of FIG. 3 is constructed | assembled using the steel pipe pile of FIG. 4, and a superstructure is installed. It is a figure which shows roughly the experimental apparatus for confirming the effect of the pile foundation structure of FIG. It is a graph which shows the relationship between the drawing amount when a acryl tube is pulled out by the experimental apparatus of FIG. 8, and a load. It is a figure which shows roughly the pile foundation structure of the conventional jetty.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

<First Embodiment>
FIG. 1 is a diagram schematically showing a pile foundation structure according to the first embodiment.

  As shown in FIG. 1, the pile foundation structure according to the present embodiment has the steel pipe pile P driven into the ground G from the bottom S1 below the water surface S for the construction of the pier. The superstructure U is installed on the upper part of the pile P, but the partition plate 10 is provided as a partition part separating the upper part and the lower part inside the pile P, and a part 12a of the lower part 12 is in a sealed saturated state. It is.

  That is, the steel pipe pile P of FIG. 1 has a partition plate 10 provided in the pipe, and is divided into an upper portion 11 and a lower portion 12 by the partition plate 10. The partition plate 10 is made of a steel material, and is attached to the steel pipe pile P by welding or the like, for example, at a factory or the like before placing, so that the upper portion 11 and the lower portion 12 of the steel pipe pile P are completely cut off.

  As shown in FIG. 1, when the steel pipe pile P is driven into the ground G from the water bottom S1, the upper part 11 of the partition plate 10 of the steel pipe pile P is filled with water, and the water level in the upper part 11 is the water level that is the outside water level. The level is the same as S, so that there is no head difference between the inside and outside of the pile P.

  Moreover, after placing the steel pipe pile P, a part 12a of the lower part 12 of the partition plate 10 of the steel pipe pile P is brought into a sealed saturated state. That is, by placing the steel pipe pile P, a part 12a formed between the partition plate 10 and the ground surface S2 in the lower part 12 of the steel pipe pile P is water and ground material (viscous soil, sandy soil, Filled with gravel, stone, etc.) and saturated, the lower part 12 is sealed. Note that a part 12a of the lower part 12 may be filled with water only to be in a sealed saturated state. However, the height position of the ground surface S2 is between the bottom S1 and the tip Z of the pile P depending on the ground conditions around the pile.

  As described above, when the pulling force V1 is applied to the pile P in the vertical direction due to the horizontal force due to the inertial force at the time of the earthquake, the lower portion 12 of the steel pipe pile P is set in a hermetic saturated state by keeping the lower portion 12 in the steel pipe pile P hermetically saturated. As a result, a suction force (suction) is generated and acts as a resistance force that resists the pull-out force V1. In this way, the resistance force / stability against pulling out of the pile P can be increased without depending on the expansion of the pile diameter or the increase in the buried length (the circumferential frictional force between the pile and the ground). For this reason, it is possible to improve the stability of the pile foundation structure such as a pier against earthquakes and the like, and the pile diameter is not increased and the embedment length is not increased. Therefore, the cost is not so bulky and economical.

  Moreover, the installation position (installation depth) of the partition plate 10 is brought into close contact with the ground surface S2 in the steel pipe pile P as much as possible, and the effect of the suction force (suction) is higher as the distance t between the partition plate 10 and the ground surface S2 is smaller. ,preferable. Moreover, the effect of a suction force (suction) becomes high, so that the penetration length to the ground G of the steel pipe pile P is long.

<Second Embodiment>
FIG. 2 is a diagram schematically showing a pile foundation structure according to the second embodiment.

  The pile foundation structure in FIG. 2 is different from the pile foundation structure in FIG. 1 in that the upper portion 11 (on the partition plate 10) of the steel pipe pile P of the pile foundation structure in FIG. . That is, as shown in FIG. 2, the filling material 13 made of a ground material is filled in the upper part 11 of the partition plate 10 of the steel pipe pile P. In addition to the ground material, the filling material 13 may be a steel pad or concrete glass. By filling the filling material 13 in the pile P, a role as a counter for the pulling force V1 of the pile P can be expected. The resistance force due to the suction force (suction) generated in the lower portion 12 of the steel pipe pile P that is in the hermetically saturated state of the steel pipe pile P with respect to the pulling force V1 of the pile P increases and becomes more effective.

  The filling height of the filling material 13 is preferably kept below the water surface S as much as possible. If it is filled to the vicinity of the pile head, the pile weight will be increased excessively, and it will be necessary to consider the lack of bearing capacity at the tip of the pile, and there is also the possibility of increasing the inertial force during earthquakes etc. It is not preferable to fill up to the vicinity of the pile head. The upper part of the filling material 13 is filled with water, and the water level in the upper part 11 is set to the same level as the water surface S, which is the outer water level, in the same manner as in FIG.

<Third Embodiment>
FIG. 3 is a diagram schematically showing a pile foundation structure according to the third embodiment.

  The pile foundation structure of FIG. 3 differs from the pile foundation structure of FIG. 2 in that negative pressure is applied to a part 12a of the lower portion 12 of the partition plate 10 in the pile foundation structure of FIG. Thus, by making the portion 12a of the lower part 12 a negative pressure state instead of the sealed saturation state of FIGS. 1 and 2, the effect of the suction force (suction) is enhanced, and the sealed saturation state of FIGS. Since the suction force (suction) generated in the lower portion 12 is increased, the resistance force of the pile P to the pulling force V1 is further increased.

  Further, an osmotic flow j (downward osmotic flow) directed toward the tip of the steel pipe pile P according to the water head difference k between the water surface S and the water level h2 in the lower portion 12 of the steel pipe pile P is generated outside the steel pipe pile P. The seepage flow j toward the tip of the steel pipe pile P will cause an increase in effective stress on the ground around the pile P and contribute to an increase in the peripheral friction force between the pile P and the ground G. I can expect.

  In addition, although the upward seepage flow is generated in the steel pipe pile P and the ground in the steel pipe pile P is assumed to decrease in effective stress, the circumferential surface in the steel pipe pile P with respect to the pulling force V1 of the pile P There is no impact because friction with the ground is not considered. However, care must be taken so that the ground in the steel pipe pile does not heave or boiling due to upward seepage flow.

<Fourth Embodiment>
FIG. 4 is a diagram schematically showing a configuration of a steel pipe pile according to the fourth embodiment.

  The structure of FIG. 4 is an example of the steel pipe pile for implement | achieving the pile foundation structure of FIGS. 1-3. That is, the steel pipe pile P has a structure in which a partition plate 10 made of a steel material is welded and attached in advance in a factory to completely block the upper portion 11 and the lower portion 12 of the pile P, and as shown in FIG. By attaching the open / close valves 21, 22, and 23, the steel pipe pile P has a structure that can adjust water flow inside and outside and shut off.

  The valve 21 is attached at a position corresponding to the upper part 11 of the partition plate 10 of the steel pipe pile P. The valves 22 and 23 are positions corresponding to a part 12a of the lower part 12 of the partition plate 10 of the steel pipe pile P. The valve 22 is attached immediately below the partition plate 10, and the valve 23 is located below the valve 22 from the bottom S1. Attach it so that it is positioned above.

  Note that the valve 21 of FIG. 4 may be omitted, and a water passage hole of, for example, about 25 mm may be provided in the steel pipe pile P instead of the valve 21 so as to communicate the inside and outside of the pile P.

  Moreover, when constructing the pile foundation structure of FIGS. 1 and 2, the valve 23 may be omitted.

  Next, with reference to the flowcharts of FIGS. 5, 6, and 7, steps for constructing each pile foundation structure of FIGS. 1 to 3 using the steel pipe pile P of FIG. 4 and installing the superstructure will be described. To do.

  (1) The process of constructing the pile foundation structure and superstructure shown in FIG. 1 will be described with reference to FIG. First, the valves 21, 22 and 23 are opened (S 01) so that a water head difference does not occur inside and outside the upper portion 11 of the steel pipe pile P.

  Next, the steel pipe pile P is driven from the bottom S1 to the ground G so that the pile tip Z reaches the support layer G1 (S02). These steps S01 and S02 are repeated to place a predetermined number of steel pipe piles P (S03). Next, the valves 21, 22, and 23 of all the piles P are closed (S04). As described above, the pile foundation structure shown in FIG. 1 is completed (S05). Next, an upper work is installed on the upper part of the steel pipe pile P (S06).

  As described above, the pile foundation structure and the superstructure U of FIG. 1 can be completed. At this time, the lower part 12 in the steel pipe pile P is in a sealed saturation state.

  (2) The process of constructing the pile foundation structure and superstructure shown in FIG. 2 will be described with reference to FIG. First, the valves 21, 22, and 23 are opened (S11), and then the steel pipe pile P is driven from the bottom S1 to the ground G so that the pile tip Z reaches the support layer G1 (S12). These steps S11 and S12 are repeated to place a predetermined number of steel pipe piles P (S13). Next, a predetermined amount of filling material is put into all the steel pipe piles P from the pile head (S14). Next, the valves 21, 22, and 23 of all the piles P are closed (S15).

  The pile foundation structure of FIG. 2 is completed as described above (S16). Next, an upper work is installed on the upper part of the steel pipe pile P (S17).

  As described above, the pile foundation structure and superstructure shown in FIG. 2 can be completed. At this time, the lower part 12 in the steel pipe pile P is in a sealed saturation state.

  (3) The process of constructing the pile foundation structure and superstructure shown in FIG. 3 will be described with reference to FIG. First, the valves 21, 22, and 23 are opened (S21), and then the steel pipe pile P is driven from the bottom S1 to the ground G so that the pile tip Z reaches the support layer G1 (S22). These steps S21 and S22 are repeated to drive a predetermined number of steel pipe piles P (S23). Next, a predetermined amount of filling material is put into all the steel pipe piles P from the pile head (S24).

  Next, a suction hose is connected to the valve 22, and the other end of the suction hose is opened to the atmosphere (S25). Then, a hose is connected to the valve 23, and a pump is connected to the other end of the hose (S26). Next, the water in the part 12a of the lower part 12 of the steel pipe pile P (between the partition plate 10 and the ground surface S2 in the steel pipe pile P) is replaced with air by a pumping pump connected to the valve 23 (S27). Thereafter, the valves 22 and 23 are closed, and the hose of the valve 23 and the pump are removed (S28).

  Next, a vacuum pump is connected to the end of the suction hose of the valve 22 opened to the atmosphere (S29). Next, the valve 22 is opened, the space in the lower part 12 of the steel pipe pile P is reduced by a vacuum pump, and a negative pressure is applied (S30). After applying a predetermined negative pressure, the valve 22 is closed, and the suction hose and the vacuum pump are removed (S31). The above steps S25 to S31 are repeated for a predetermined number of steel pipe piles P (S32). In addition, when there are many numbers of steel pipe piles, the ends of the suction hoses and the ends of the hoses of all the piles are combined into one piece respectively, and steps S25 to S31 are performed once for all the piles. You may do it.

  The pile foundation structure of FIG. 3 is completed as described above (S33). Next, an upper work is installed on the upper part of the steel pipe pile P (S34).

As described above, the pile foundation structure and the superstructure shown in FIG. 3 can be completed.
At this time, a part 12a of the lower part 12 of the steel pipe pile P is a negative pressure space.

Experimental example

  The effect of the pile foundation structure of FIG. 1 was confirmed using the experimental apparatus of FIG. 8 simulating the pile foundation structure of FIG. That is, as shown in FIG. 8, a saturated viscous ground is created in the tank, and two acrylic tubes with a diameter of 5 cm, a length of 50 cm, and a thickness of 1 mm are installed on the ground at a depth of 45 cm. Filled with water.

  As an experimental example, the top end of one acrylic tube was covered with a vinyl disc and the gap was filled with underwater putty to completely seal it. As a comparative example, the other acrylic tube was used without being capped at the upper end.

  Each acrylic tube of the experimental example and the comparative example was drawn vertically upward at the same speed, and the resistance force (load) at that time was measured with a load cell. FIG. 9 shows the relationship between the drawing amount and the load when the acrylic tube is drawn as the measurement result.

The theoretical values 1 and 2 in the figure are calculated values when it is assumed that only the peripheral frictional force acts without considering the suction (attraction force) when the pipe is pulled out. The theoretical value 1 is a case where friction force acts on the entire peripheral surface inside and outside the acrylic tube. Theoretical value 2 is a case where the frictional force acts only on the outer peripheral surface of the acrylic tube, and the inside of the clay tube is accompanied by the viscous soil along with the acrylic tube. Here, the saturated unit sediment weight of the viscous ground is 16 kN / m ³ and the adhesive strength is 50 kN / m ² .

  As can be seen from FIG. 9, in the experimental example, the resistance (load) was about twice as large in the initial drawing (drawing amount of about 10 mm) and about five times in the latter half of drawing (about 80 mm of drawing). In addition, when only the peripheral surface friction force is taken into consideration (the friction force acts on the entire peripheral surface inside and outside the pipe), the resistance value is slightly less than three times the theoretical value 1, and the friction force acts only on the outer peripheral surface of the pipe. It shows a resistance force close to 5 times the theoretical value 2 in this case. From these results, the experimental example simulating the pile foundation structure in FIG. 1 is more effective as a resistance force for suction (suction force) than the comparative example without the suction action. I found it working.

Calculation example

  (1) Verification of the effect of filling material in Fig. 2

  Pull out when steel pipe piles φ700-9t, φ1100-12t, φ1500-16t 3 case pile specifications, water depth is 10m, partition plate is the same level as the bottom of the ground, sand is inserted 4m and 8m as filling material Table 1 below shows an example of calculation related to the ballast charging effect.

  In the calculation result of Table 1, the resistance force (push-in force) against the extraction of 14.6 to 135.4 kN can be obtained by inserting the filling material. For example, when the pulling force is 1000 kN, the share is about 1% to 14%. As a matter of course, the larger the pile diameter and the filling height of the filling material, the more effective the medium unit weight of the filling material in water.

  (2) Verification of the effect of osmotic flow in Fig. 3

  The steel pipe pile depth is 10m, the water depth is 10m, the water level in the steel pipe pile is lowered by 2m from the bottom floor, the partition plate is at the same level as the bottom floor, and the void pressure at the bottom of the steel pipe pile is equal to the atmospheric pressure. Is calculated by the following equation.

i = h / L = (10 + 2) / (10 + 8) = 0.667
Where, h: hydraulic head difference, L: permeability length

The osmotic pressure p _w generated downward on the outside of the steel pipe pile as shown in the downward osmotic flow j in FIG. 3 is calculated by the following equation.

p _w = i × γ _w × L = 0.667 × 10 × l = 6.67 × L (kN / m ² )
Where γ _w : unit volume weight of water (= 10 kN / m ³ ), L: penetration distance (m)

  Next, the effective stress σ 'of the ground outside the steel pipe pile can be obtained by the following equation.

σ '= (γ _sat -γ _w ) × z = ( _17-10 ) × z = 7 × z (kN / m ² )
Where γ _sat : Saturated unit volume weight of soil (= 17kN / m ³ ), z: Depth of ground (m)

Therefore, the effective stress σ ′ _w considering the osmotic pressure is a value obtained by adding the osmotic pressure p _w to the effective stress σ ′ as follows.

σ ' _w = σ' + p _w = 6.67 × L + 7 × z

  Here, since the infiltration distance L is equal to the ground depth z, the effective stress considering the osmotic pressure is summarized as follows.

σ ' _w = 13.67 × z

Therefore, the ratio between the effective stress σ 'and σ' _w considering osmotic pressure is
σ ' _w /σ'=13.67 / 7 = 1.95 ≒ 2.0
Thus, the effective stress is doubled by the osmotic pressure.

When the ground around the steel pipe pile is cohesive soil, the cohesive force c _u of cohesive soil is given by the following equation as a linear function of effective soil covering pressure.

c _u / p = 0.28 ~ 0.30
Where p: consolidation stress (= effective stress σ ')

Therefore, by applying osmotic pressure, the adhesive force c _u is also doubled, and the peripheral friction force between the pile and the ground is obtained as the product of the outer peripheral area of the pile and the adhesive force c _u of the ground. Doubled. In this manner, the downward osmotic flow j on the outer side of the steel pipe pile P generated according to the water head difference k between the water surface S of FIG. It can be seen that the surface friction force increases.

  As described above, the modes for carrying out the present invention have been described. However, the present invention is not limited to these, and various modifications can be made within the scope of the technical idea of the present invention. For example, in the present embodiment, a pier that is a typical pile foundation structure in a harbor is described, but the present invention is not limited to this, and may be another pile foundation structure on water or on land.

  Moreover, although the method of attaching the partition plate 10 in the pile P has welding, it is not limited to this, Of course, you may make it attach by another method.

  Moreover, you may make it give a negative pressure to the part 12a of the lower part 12 of the partition plate 10 like FIG. 3 in the pile foundation structure of FIG.

  According to the pile foundation structure of the present invention, the pile foundation structure construction method, and the pile used for these, the resistance to pulling out the pile can be increased without relying on the expansion of the pile diameter or the increase in the buried length, The stability of pile foundations against earthquakes can be improved economically.

10 Partition plate (partition)
11 Upper part 12 Lower part 12a Lower part 13 Filling material 21, 22, 23 Opening and closing valve, valve P Steel pipe pile, foundation pile, pile F Peripheral friction force G Ground G1 Support layer V1 Pulling force against pile P J seepage flow S Water surface S1 Water bottom S2 Ground surface h2 in pile P Water level k in lower part 12 Water head difference Z between water surface S and water level h2 Tip of pile P

Claims (9)

A partition part is provided in a foundation pile made of a hollow tube, and the foundation pile is divided into an upper part and a lower part in the vertical direction by the partition part,
Resist the pulling force when a pulling force acts on the foundation pile by sealing at least a part of the lower part of the foundation pile placed in the ground with water or water and ground material. Pile foundation structure characterized by generating suction force   The pile foundation structure according to claim 1, wherein resistance to the pulling force is obtained by disposing a filling material in the upper part.   The pile foundation structure according to claim 1 or 2, wherein a space surrounded by the partition portion and a ground surface in the foundation pile is set to a negative pressure in the lower part.   The pile foundation structure according to any one of claims 1 to 3, wherein the foundation pile is placed on a water bottom, and the water level of the upper part is set to the same level as an external water level. A partition part is provided in a foundation pile made of a hollow tube, and the foundation pile is divided into an upper part and a lower part in the vertical direction by the partition part,
A method for constructing a pile foundation structure, wherein the foundation pile is placed in the ground, and then at least a part of the lower portion is saturated with water or water and ground material and then sealed.   The method for constructing a pile foundation structure according to claim 5, wherein after the foundation pile is placed, a filling material is introduced into the upper portion.   The construction method of a pile foundation structure according to claim 5 or 6, wherein a space surrounded by the partition portion and a ground surface in the foundation pile is made negative pressure in the lower part.   The construction method for a pile foundation structure according to any one of claims 5 to 7, wherein the foundation pile is placed on a water bottom, and the water level of the upper part is set to the same level as an external water level.   A pile comprising a hollow tube used in the construction method of the pile foundation structure according to any one of claims 1 to 4 or the pile foundation structure according to any one of claims 5 to 8, A stake characterized by providing a partition inside.

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