JP2005016292A - Combined footing of pile and diaphragm wall - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide the combined footing of a pile and a diaphragm wall, by which the axial-force load of a building can be borne sufficiently in a soft ground, a response displacement in the case of an earthquake is decreased and a habitability is improved and upper skeletons are lessened by the diminution of an input to an upper structure or the classifications of the structures can be changed while the reduction of a pile section and a liquefaction countermeasure are carried out and it is possible that a total cost is reduced even by using the diaphragm wall and the terms of works are shortened. <P>SOLUTION: In the combined footing 14 of the piles and the diaphragm wall, the combined footing 14 has a plurality of the piles 16a and 16b installed up to a bearing ground 22 and the diaphragm wall 18 integrally mounted together with the piles 16a, 16b, surrounding the piles, and is built at a place, where a soft ground is deposited in 30 m or more. The diaphragm wall 18 is disposed along the outer periphery of the building 10 having an approximately square form in a plan view, and formed in a depth shallower than the ground 22. The piles 16a are disposed even at the places of an outermost periphery in the diaphragm wall 18, and the axial-force load of the building 10 is borne to the piles 16a. Only a horizontal load in the case of the earthquake is borne mainly by the diaphragm wall 18. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a composite foundation of a pile and a continuous underground wall, and particularly to a composite foundation of a pile and a continuous underground wall in soft ground.

  Generally, foundation piles are used to receive the axial force of buildings.

  In soft ground, as a countermeasure when a horizontal load is applied in the event of an earthquake, the pile head is reinforced by increasing the pile diameter by a length equivalent to about 5 times the pile diameter from the top or winding a steel pipe. I am doing so.

  However, when building a high-rise building in a place where soft ground accumulates thickly, the response displacement value of the building increases only by increasing the pile head, so the pile foundation is surrounded by continuous underground wall piles. Things may be done.

  Thus, when using a continuous underground wall as a continuous underground wall pile, the thickness of the continuous underground wall pile is determined by the axial force load, and the thick continuous underground wall pile is made long to the support ground. The amount of excavation and concrete must be increased, which is very uneconomical, the construction period is lengthened, the amount of excavated soil is increased, and the construction soil is increased.

  In addition, if the supporting ground is deep, it is difficult to construct a thick continuous underground wall pile deeply and accurately.

Therefore, a technology to reinforce the building with piles and ground anchors rooted to the supporting ground in the ground deformation suppression region surrounded by this continuous ground wall is proposed by rooting the continuous underground wall shallower than the supporting ground. (See Patent Document 1).
JP 2001-288758 A

  In such a technique as described in Patent Document 1, the continuous underground wall supports the vertical load of the building together with the pile, and the pile is provided at a position away from the continuous underground wall. It has become.

  As described above, in order to support the vertical load of the building, the ground wall must be hard to some extent even though the continuous underground wall is shallower than the supporting ground.

  On the other hand, for example, in the soft ground such as the Tokyo Bay area, the vertical load of the building cannot be sufficiently supported by the above-described technique.

  The object of the present invention is to sufficiently support the axial load of a building on soft ground, to reduce the response displacement at the time of earthquake, to improve the habitability, to reduce the upper frame by reducing the input to the superstructure, and to the structure Providing a composite foundation of piles and continuous underground walls that can reduce the cost of construction and shorten the construction period even when using continuous underground walls, making it possible to change types and reduce pile cross-section and liquefaction measures. There is.

In order to achieve the above object, the composite foundation of the pile and continuous underground wall of the present invention includes a plurality of piles that are provided to reach the supporting ground, and a continuous underground that is provided integrally with the pile surrounding the pile. A composite foundation of a pile and a continuous underground wall that has a wall and is built in a place where more than 30m of soft ground is deposited,
The continuous underground wall is disposed along the outer periphery of a substantially square or polygonal building in plan view, and is formed shallower than the supporting ground,
The pile is also disposed at the outermost peripheral position in the continuous underground wall, and the pile bears the axial load of the building,
The continuous underground wall mainly bears only a horizontal load during an earthquake.

  According to the present invention, the continuous underground wall shallower than the supporting ground is disposed along the outer periphery of the substantially square or polygonal building in plan view, and the pile is also disposed at the outermost peripheral position in the continuous underground wall. The pile is loaded with the axial load of the building, and the continuous underground wall is loaded with only the horizontal load mainly during an earthquake, so that the building is supported stably and is constructed in a substantially square shape. By enclosing the lower part of the building in a highly rigid state with the underground wall and making it difficult to deform, it is possible to reduce the response displacement during an earthquake and improve the comfortability.

  Therefore, it is possible to sufficiently support the building's axial load even in places where the ground has accumulated 30 m or more, and to reduce the earthquake input to the superstructure.

  Here, “substantially square” means that the ratio of the vertical and horizontal sides is about 0.7 to 1.0.

  The polygon means a shape having a cross shape in plan view, a pentagon, a hexagon, an octagon, or the like.

  In addition, by reducing the seismic input to the superstructure by this continuous underground wall, the upper frame is reduced and the structural type, for example, the concrete-filled steel tube (CFT) structure and SRC structure, which have high yield strength, are changed to the RC structure. Thus, the cost of the upper structure can be reduced, and even when a high-cost continuous underground wall is used, the total cost including the upper structure can be reduced.

  In addition, the pile only needs to receive an axial load, horizontal load is hardly applied, so there is no need to increase the diameter of the pile head, and the pile diameter can be reduced, reducing the cost required for the pile. And the construction period can be shortened.

  In addition, the continuous underground wall only needs to receive only horizontal force, and it is not necessary to bear the axial force, so the continuous underground wall can be made thinner and shorter, reducing costs and construction time. Is possible.

  Here, the continuous underground wall includes an RC wall, an S wall, an SRC wall, and a soil cement wall, and the pile includes a cast-in-place pile and a steel pipe pile.

  Furthermore, it is possible to prevent liquefaction in the portion surrounded by the continuous underground wall.

  Further, since the continuous underground wall does not reach the supporting ground, the water permeability is not hindered below the continuous underground wall, and the surrounding environment can be prevented from being affected.

  In this invention, the depth to the said support ground can be used for the ground of 40m-70m.

  By setting it as such a structure, when the depth of a support ground is deep, a cost reduction effect can be enlarged compared with the case where a continuous underground wall is formed to a support ground.

  In this invention, the depth of a continuous underground wall can be 30 to 70% with respect to the depth of a support ground from a foundation bottom.

  By adopting such a configuration, the depth of the continuous underground wall is set to 30% with respect to the depth from the foundation bottom to the supporting ground, so that the continuous underground wall is formed to the supporting ground. On the other hand, a continuous underground wall can be formed in a range in which the amount of displacement is not significantly changed, and cost merit can be increased.

  Also, by setting the depth of the continuous underground wall to 70% of the depth from the foundation bottom to the supporting ground, the cost merit is reduced, but it is equivalent to the case where the continuous underground wall is formed to the supporting ground. The amount of displacement can be kept small.

  In the present invention, the soft ground can sufficiently support the axial load of the building even if the ground has a shear wave velocity of 150 m / s or less and an initial primary natural period longer than 0.6 seconds. The input to the structure can also be reduced.

  In the present invention, when the ratio between the primary natural period of the ground at the time of the earthquake and the primary natural period of the building is 0.6 to 1.0, the building maximum response displacement and the building maximum response acceleration are effectively reduced. can do.

In the present invention, the soft ground includes an intermediate layer that is lower in rigidity than the support ground and higher in rigidity than the upper layer,
The intermediate layer has a layer thickness that reaches the support ground at a predetermined depth from the ground surface,
The continuous underground wall may be formed to a depth up to the intermediate layer.

  By adopting such a configuration, in the soft ground, when the intermediate layer having lower rigidity than the supporting ground and higher rigidity than the upper layer has a layer thickness that reaches the supporting ground at a predetermined depth from the ground surface, it is continuous. By forming the underground wall to a depth up to the middle layer, the axial load on the pile is reduced by supporting a certain amount of axial load on the continuous underground wall, and the thickness of the pile is reduced. This can reduce the cost.

  Also, by enclosing the lower part of the building with high rigidity with a continuous underground wall and supporting it with an intermediate layer to make it difficult to deform, the response displacement at the time of earthquake can be reduced and the comfortability can be improved. it can.

  Furthermore, the input of seismic motion to the building can be suppressed, which is effective in designing the superstructure.

  In the present invention, in the soft ground, when the intermediate layer having lower rigidity than the supporting ground and higher rigidity than the upper layer has a layer thickness that does not reach the supporting ground at a predetermined depth from the ground surface, the continuous underground wall Is formed at a depth that reaches the support ground only at the corner, and other portions are formed at a depth up to the intermediate layer, so that even if a soft layer continues below the intermediate layer, the corner of the continuous underground wall By extending to the supporting ground, the rigidity against the horizontal load can be increased by the high rigidity at the corner, and the axial load can be supported, and the peripheral corner pile can be omitted, and it is surrounded by the continuous underground wall. Since the pile only bears the axial force, it is possible to reduce the cost by reducing the thickness of the pile.

  Moreover, since the lower part of the building is surrounded by the continuous underground wall up to the intermediate layer and supported by the intermediate layer, the response displacement at the time of an earthquake can be reduced and the habitability can be improved.

  An intermediate layer having a rigidity lower than that of the supporting ground and higher than that of the upper layer is a viscous soil having an N value of 10 or more or a sandy soil having an N value of 20 or more, and a ground having a shear wave velocity of 250 m / s or more. can do.

  By setting it as such a structure, a horizontal displacement of a continuous underground wall can be made small by an intermediate | middle layer, and a certain amount of axial load can be borne.

  In these cases, the depth to the intermediate layer can be 10 m or more.

  By adopting such a configuration, it is possible to form a continuous underground wall at a predetermined depth and to apply a sufficient load of horizontal force.

  Furthermore, the layer thickness of the intermediate layer can be 5 m or more.

  With such a configuration, the horizontal displacement of the continuous underground wall can be reduced by the intermediate layer, and a certain axial force load can be supported.

  In this case, the lower end of the continuous underground wall can be embedded in the intermediate layer.

  By setting it as such a structure, the lower part of a continuous underground wall can be restrained to a rigid intermediate | middle layer, and it becomes possible to bear a horizontal load reliably.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIGS. 1-5 is a figure which shows the composite foundation of the pile concerning one embodiment of this invention, and a continuous underground wall.

  FIG. 1 is a cross-sectional view showing a state in which a building is constructed on a composite foundation of piles and continuous underground walls according to this embodiment, and FIG. 2 is a plan view of the building in FIG.

  The building 10 is constructed on a soft ground 12, for example, a soft ground having a shear wave velocity of 150 m / s or less deposited from the support ground by 30 m or more and an initial primary natural period longer than 0.6 seconds. It is a high-rise building with a plan view that is almost square.

  Specifically, as shown in FIG. 2, the length L1 of one side in a plan view is 36 m and the length L2 of the other side is 36 m.

  L1 and L2 can be arbitrarily set within a range of 30 m to 50 m.

  The height H (see FIG. 1) of the building 10 is 150 m.

  Since the building 10 is constructed on the soft ground 12, it is supported by the composite foundation 14.

  The composite foundation 14 is a composite of a plurality of piles 16 and a continuous underground wall 18.

  The pile 16 is a bottomed pile that reaches from the foundation bottom 20 to the support ground 22 at the column corresponding position of the building 10 and is embedded.

  Of course, the foundation up to the foundation bottom 20 includes a case having a basement.

  The continuous underground wall 18 is disposed so as to surround the outer peripheral pile 16a and the inner pile 16b along the outer periphery of the substantially square building 10 in plan view, and is integrated with the outer peripheral pile 16a and the inner pile 16b via the underground frame and the footing 24. Has been.

  Thus, the building 10 can be stably supported by arranging the continuous underground wall 18 along the outer periphery of the building 10 that is substantially square in plan view, and the length of one side of the building 10 in plan view is The longer it is, the more stable it is.

  The continuous underground wall 18 is set to a depth La that is shallower than the depth Lt from the foundation bottom 20 to the support ground 22.

  By reducing the depth La of the continuous underground wall 18 in this way, not only the depth Lt from the foundation bottom 20 to the support ground 22 is reduced, but also the construction period can be shortened. It is also possible to plan.

  And the outer periphery pile 16a is arrange | positioned also in the outermost periphery position in the continuous underground wall 18, and it is made to support the axial force load of the building 10 with the outer periphery pile 16a and the internal pile 16b, Only the horizontal load at the time of an earthquake is supported.

  In this way, the continuous underground wall 18 bears the axial load by causing the outer pile 16a and the internal pile 16b to support the axial load of the building 10 and the continuous underground wall 18 to support the horizontal load during the earthquake. Therefore, the thickness of the continuous underground wall 18 can be reduced, and the cost and construction period can be further reduced.

  Moreover, since the outer peripheral pile 16a and the inner pile 16b bear an axial load and hardly bear a horizontal load at the time of an earthquake, there is no need to reinforce the pile head, the pile diameter can be reduced, and further cost is increased. Can be reduced and the construction period can be shortened.

  Furthermore, since the continuous underground wall 18 has high horizontal rigidity, it is possible to reduce the response displacement at the time of an earthquake and improve the habitability, and further, by reducing the input to the building 10 that is the superstructure, The structure of the building 10 can be changed, for example, from the SRC structure or CFT structure, which has a high yield strength, to the RC structure, including the building even though the high-cost continuous underground wall 18 is used. Total cost can be reduced.

  In addition, it is possible to prevent liquefaction of the ground surrounded by the continuous underground wall 18 during an earthquake.

  Here, the depth La of the continuous underground wall 18 is 30 to 70% with respect to the depth Lt of the support ground 22 from the foundation bottom 20.

  When the depth from the ground surface 12a to the supporting ground 22 is 30 m to 70 m, and more preferably 40 m to 70 m, cost merit increases.

  Here, the relationship between the depth (length) of the continuous underground wall 18, the cost ratio, and the horizontal displacement is shown in FIG.

  In these calculations, the thickness of the continuous underground wall was 1.5 m, 25 internal piles, 24 outer peripheral piles, and the foundation part of FIG. 1 was modeled in three dimensions and loaded based on the inertial force during earthquakes.

  In FIG. 3, the cost ratio indicates the ratio between the case where the continuous underground wall is formed up to the depth Lt of the support ground 22 and the case where the continuous underground wall is formed at a depth La smaller than that. FIG. 3 shows a case where the depth Lt from the base bottom 20 to the support layer 22 is 60 m.

  From FIG. 3, if the depth La from the foundation bottom 20 to the continuous underground wall 18 is 45 m, the continuous underground wall 18 was formed with the depth Lt to the support ground 22 even if the outer peripheral pile 16a increased. It can be seen that the cost ratio is equivalent to the case, and if it is shorter than that, the cost ratio becomes smaller and the cost is reduced.

  Therefore, La / Lt may be about 70% or less.

  Moreover, if the depth La of the continuous underground wall 18 is 15 m or more, it turns out that the change of a horizontal displacement amount becomes small.

  Furthermore, since the horizontal shift position changes according to the type of ground, La / Lt is set to 30% or more with some allowance.

  Next, FIG. 4 shows an example of a trial calculation of the relationship between the depth La of the continuous underground wall 18 and the cost.

  FIG. 4 shows a state in which a composite foundation is formed on the basis of a continuous underground wall having a thickness of 1.5 m under the condition that the depth Lt from the foundation bottom 20 to the supporting ground 22 is 50 m.

  When (1) sets the depth La of the continuous underground wall 18 to 20 m (La / Lt = 40%), (2) sets the depth La of the continuous underground wall 18 to 20 m (La / Lt = 40%). ) And the case where the wall thickness of the continuous underground wall 18 is reduced to 1.2 m.

  In the case of (1), the cost can be reduced to 81%, and in the case of (2), the cost can be reduced to 75%.

  Further, FIG. 5 shows the relationship between the cycle ratio and the response ratio by the centrifugal loading model experiment.

  In this experiment, a soft ground is assumed as the centrifugal acceleration 50G, and the level of seismic force is changed in three stages.

  In addition, a pile foundation model in which 12 outer diameter piles with a diameter of 10 mm and 4 inner piles with a diameter of 12 mm are rigidly joined by footing, and a continuous ground reaching 4 mm of inner piles with a diameter of 12 mm and a supporting ground of 2.5 mm in length and 250 mm in length. A composite foundation model in which the middle wall was rigidly joined by footing was used.

  FIG. 5 (1) shows the relationship between the cycle ratio and the building maximum response acceleration ratio, and FIG. 5 (2) shows the relationship between the cycle ratio and the building maximum response displacement ratio.

  The periodic ratio is the ground primary natural period / the primary natural period of the building, the building maximum response acceleration ratio is the composite building maximum response acceleration / pile foundation building maximum response acceleration, and the building maximum response displacement ratio is the composite foundation building. The maximum response displacement / pile foundation building maximum response displacement is shown.

  As a result of the experiment, it was found that both the maximum response acceleration ratio of the building and the maximum response displacement ratio of the building rapidly decrease when the cycle ratio becomes 0.6 to 1.0.

  Therefore, it can be seen that the continuous underground wall functions effectively when the cycle ratio is 0.6 to 1.0, and is effective for horizontal load processing during an earthquake.

  From this, it is considered that the same result can be obtained even when the continuous underground wall is shallower than the supporting ground as in the present embodiment.

  FIG. 6 shows a composite foundation of piles and continuous underground walls according to another embodiment of the present invention.

  In this embodiment, the soft ground 12 is accumulated 30 m or more from the support ground 22, and the soft ground 12 has an intermediate layer 32 that is lower in rigidity than the support ground 22 and higher in rigidity than the upper layer 30. Is present.

  The intermediate layer 32 has a property as shown in FIG. 7 and has a layer thickness reaching the support ground 22 at a predetermined depth, for example, 10 m or more from the ground surface 12a.

  The intermediate layer 32 is a clay soil having an N value of 10 or more or sandy soil having an N value of 20 or more, and has a shear wave velocity of 250 m / s or more.

  The layer thickness of the intermediate layer 32 is 5 m or more.

  The composite foundation 14 in the soft ground 12 having such an intermediate layer 32 allows a plurality of piles 16 that are bottom-pile piles to reach the support ground 22 from the foundation bottom of the building 10 and to be embedded, and on the outer periphery of the building 10. A continuous underground wall 18 is formed along the intermediate layer 32 along the depth.

  The lower end of the continuous underground wall 18 is in a state of being rooted in the upper part of the intermediate layer 32.

  In this way, by supporting the lower end of the continuous underground wall 18 on the intermediate layer 32, a certain axial force load is supported on the continuous underground wall 18 and the load of the axial load on the pile 16 is reduced. The thickness of 16 can be reduced, and the cost can be reduced.

  Moreover, since the lower part of the building 10 is surrounded by the continuous underground wall 18 up to the intermediate layer 32 and is supported by the intermediate layer 32, the response displacement at the time of an earthquake can be reduced and the habitability can be improved. .

  Other configurations and operations are the same as those in the above embodiment, and a description thereof will be omitted.

  Next, a composite foundation when the intermediate layer shown in FIG. 6 reaches the support ground at a predetermined depth from the ground surface, and a case where an underground continuous wall of the same length when the intermediate layer is not formed are formed. FIG. 8 shows the displacement ratio compared to the case where the continuous underground wall is formed.

  In the calculation, the foundation was modeled in three dimensions and loaded based on the inertial force during the earthquake.

  In this trial calculation, it is assumed that the depth to the support layer is 60 m. In case 1, the shear wave velocity is 120 m / s at a depth of 0 to 14 m, 350 m / s at 14 m to 25 m, and 250 m / s at 25 m to 40 m. In s, 40 m to 60 m, 350 m / s, and the intermediate layer reaches the supporting ground from a depth of 14 m.

  In case 2, the shear wave velocity is 120 m / s at a depth of 0 to 19 m, 350 m / s at 19 to 30 m, 250 m / s at 30 to 45 m, 350 m / s at 45 to 60 m, and the intermediate layer from a depth of 19 m. It has reached the support ground.

  When there is no intermediate layer as a comparative reference, the ground condition is that the shear wave velocity is 120 m / s up to 0 to 60 m.

  In addition, the trial calculation conditions of the composite foundation were as follows: the thickness of the continuous underground wall was 1.5 m, 25 internal piles, and 24 external piles.

  As shown in FIG. 2 (2), the trial calculation result under the conditions shows that in the case 1, the displacement ratio with the case of the 60m continuous underground wall in which the continuous underground wall is formed up to the support layer is 1.6 if there is no intermediate layer, 1.5 if there is an intermediate layer, and in case 2 it is 1.3 if there is no intermediate layer, and 1.2 if there is an intermediate layer. The amount of deformation is about 10% by stopping the continuous underground wall at a ratio of 60m continuous underground wall compared to the case where the continuous underground wall is the same length in soft ground with no intermediate layer. Turned out to be smaller.

  As is clear from FIG. 3, when the displacement ratio is 1.5 or less, the continuous underground wall has to be lengthened by about 2 m in order to lower the ratio by 0.1, so the intermediate layer is used. The effect is great.

  In this case, the continuous underground wall was calculated assuming that the lower end of the continuous underground wall was 1 m in the middle layer, the case of Case 1 was the underground continuous wall of 15 m, and the case 2 was the continuous underground wall of 20 m.

  In addition, when the lower end of the continuous underground wall is embedded in the intermediate layer about 5 m, for example, when there is an intermediate layer at 20 m, the length of 25/60 = 42% and the displacement amount is 60 m The same earthquake resistance will be obtained.

  Next, the result of having examined the intermediate layer shown in FIG. 9 about the property at the time of an earthquake is shown.

  As shown in FIG. 1 (1), the ground structure is a shear wave velocity of 120 m / s at 0 to 20 m, 250 m / s at 20 m to 40 m, 300 m / s at 40 m to 50 m, 350 m / s at 60 m to 60 m, and 60 m. The depth is 450 m / s (equivalent to supporting ground).

  Here, as shown in Fig. 2 (2), two types of seismic waves, a notification wave and a critical wave, are set, and a one-mass model with a primary natural period of 0.27 Hz (3.8 seconds) is imagined. The dynamic response was calculated by

  There are three types of foundations: one with a continuous underground wall of 60m up to the supporting ground, one with a supporting outer periphery pile, one with a continuous underground wall up to 20m up to the middle layer, and a foundation with only a pile. investigated.

  Comparing and examining the maximum response acceleration and maximum response displacement of buildings, the maximum response acceleration and maximum response displacement of foundations, which are important for seismic design, it was found that by using 20m continuous underground wall, the foundation maximum was higher than 60m continuous underground wall. Everything except the response acceleration is small, and considering the ground period characteristics and building characteristics, depending on the seismic wave, using the continuous underground wall up to 20m where the middle layer appears is equivalent to or superior to the case of extending to 60m. In this trial calculation, when the short continuous underground wall is used, not only the effect of reducing the displacement of the foundation but also the effect of reducing the input to the building has occurred.

  Moreover, in the comparison with the pile foundation which does not use a continuous underground wall, depending on the response value, it is reduced by 50%, which is much superior in all items than the pile foundation.

  FIG. 10 shows a composite foundation of piles and continuous underground walls according to still another embodiment of the present invention.

  In this embodiment, the soft ground 12 has an intermediate layer 34 that is lower in rigidity than the support ground 22 and higher in rigidity than the upper layer 30, and has a predetermined depth from the ground surface 12 a, for example, 10 m or more. It has a layer thickness that does not reach the supporting ground 22, for example, 5 m or more.

  The intermediate layer 34 is a clay soil having an N value of 10 or more or a sandy soil having an N value of 20 or more, and has a ground having a shear wave velocity of 250 m / s or more.

  The composite foundation 14 provided on the soft ground 12 having such an intermediate layer 34 reaches and roots the plurality of piles 16 that are bottom-up piles from the foundation bottom of the building 10 to the support ground 22 and has a continuous underground wall. Only 18 corner portions 36 are formed to a depth reaching the support ground 22, and other portions, wall portions 38 between the corner portions 36 are formed to a depth to the intermediate layer 34.

  The lower end of the wall portion 38 of the continuous underground wall 18 is in a state of being embedded in the upper portion of the intermediate layer 34.

  In this way, the continuous underground wall 18 is formed to a depth reaching the support ground 22 at the corner portion 36, and the other portion is formed to a depth to the intermediate layer 34, so that the lower side of the intermediate layer 34 is soft. Even when the lower layer 40 continues, the corner portion 36 of the continuous underground wall 18 is extended to the supporting ground 22 to ensure sufficient rigidity against the horizontal load at the corner portion, and the axial force load is substituted for the outer corner pile. The pile outside the corner can be omitted, and the pile surrounded by the continuous underground wall only bears the axial force. Therefore, the thickness of the pile can be reduced and the cost can be reduced.

  In addition, the lower part of the building 10 is surrounded by the continuous underground wall 18 up to the intermediate layer 34, and the continuous underground wall 18 is supported by the intermediate layer 34. Can be improved.

  Other configurations and operations are the same as those in the above embodiment, and a description thereof will be omitted.

  The present invention is not limited to the above-described embodiment, and can be modified into various forms within the scope of the gist of the present invention.

  In the said embodiment, although the height of a building is 150 m, it is not limited to this example, The height of a building can be changed arbitrarily.

It is sectional drawing which shows the state which built the building on the composite foundation of the pile which concerns on one embodiment of this invention, and a continuous underground wall. It is a top view of the building in FIG. It is a characteristic view which shows the relationship between the depth of a continuous underground wall, a cost ratio, and a response displacement amount. It is a figure which shows an example which calculated the relationship between the depth of a continuous underground wall, and cost. This figure shows the relationship between the cycle ratio and the response ratio in the centrifugal loading model experiment. (1) is a characteristic diagram showing the relationship between the cycle ratio and the maximum response acceleration ratio of the building, and (2) is the cycle ratio and the maximum response displacement ratio of the building. It is a characteristic view which shows the relationship. It is sectional drawing which shows the composite foundation of the pile and continuous underground wall which concern on other embodiment of this invention. It is a figure which shows an example of an intermediate | middle layer. FIG. 6 shows the displacement ratio between the composite foundation with the intermediate layer shown in FIG. 6 and the composite foundation without the intermediate layer when the continuous underground wall is formed up to the supporting ground. It is a figure which shows ground conditions, (2) is a figure which shows the ratio of the displacement in local ground conditions. FIG. 6 shows the response calculation result at the time of an earthquake when the intermediate layer of FIG. 6 is provided, (1) is a diagram showing the target ground conditions, and (2) is a continuous underground wall of 60 m length of each part. It is a figure which shows the ratio of a pile foundation. It is sectional drawing which shows the composite foundation of the pile and continuous underground wall which concern on other embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Building 12a Ground surface 14 Composite foundation 16a Perimeter pile 16b Inner pile 18 Continuous underground wall 20 Foundation bottom 22 Support ground 24 Footing 30 Upper layer 32, 34 Middle layer 36 Corner part 38 Wall part 40 Lower layer H Building height Lt Support ground Depth La La Continuous underground wall depth L1 Length of one side of the building L2 Length of the other side of the building

Claims (11)

A plurality of piles that are provided to reach the supporting ground, and a continuous underground wall that is provided integrally with the piles surrounding the pile, and is constructed in a place where the soft ground is accumulated at 30 m or more; A composite foundation of continuous underground walls,
The continuous underground wall is disposed along the outer periphery of a substantially square or polygonal building in plan view, and is formed shallower than the supporting ground,
The pile is also disposed at the outermost peripheral position in the continuous underground wall, and the pile bears the axial load of the building,
A composite foundation of a pile and a continuous underground wall, wherein the continuous underground wall mainly bears only a horizontal load during an earthquake. In claim 1,
A composite foundation of a pile and a continuous underground wall, characterized in that it is used for a ground having a depth of 40 m to 70 m to the support ground. In claim 1 or 2,
The depth of the said continuous underground wall is 30-70% with respect to the depth from a foundation bottom to a support ground, The composite foundation of the pile and continuous underground wall characterized by the above-mentioned. In any one of Claims 1-3,
The composite foundation of a pile and a continuous underground wall, wherein the soft ground is a ground having a shear wave velocity of 150 m / s or less and an initial primary natural period longer than 0.6 seconds. In any one of Claims 1-4,
A composite foundation of a pile and a continuous underground wall, wherein a ratio of a primary natural period of the ground during an earthquake and a primary natural period of a building is 0.6 to 1.0. In claim 1 or 2,
The soft ground includes an intermediate layer that is lower in rigidity than the support ground and higher in rigidity than the upper layer,
The intermediate layer has a layer thickness that reaches the support ground at a predetermined depth from the ground surface,
The composite foundation of a pile and a continuous underground wall, wherein the continuous underground wall is formed to a depth to the intermediate layer. In claim 1 or 2,
The soft ground includes an intermediate layer that is lower in rigidity than the support ground and higher in rigidity than the upper layer,
The intermediate layer has a layer thickness that does not reach the support ground at a predetermined depth from the ground surface,
The continuous foundation wall is formed at a depth reaching only the corner to the support ground, and the other part is formed at a depth up to the intermediate layer. . In claim 6 or 7,
The intermediate layer is a viscous foundation having an N value of 10 or more or a sandy soil having an N value of 20 or more, and is a ground having a shear wave velocity of 250 m / s or more. In any one of Claims 6-8,
The composite foundation of a pile and a continuous underground wall, characterized in that the depth to the intermediate layer is 10 m or more. In claims 6-9,
A composite foundation of a pile and a continuous underground wall, wherein the intermediate layer has a thickness of 5 m or more. In any one of Claims 6-10,
A composite foundation of a pile and a continuous underground wall, wherein the lower end of the continuous underground wall is embedded in the intermediate layer.

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