JP4724680B2 - Column base structure - Google Patents

Description

  The present invention relates to a column base structure configured using a pile member and a column member in an elevated structure of a road or a railway.

  Conventionally, there is a pile vent type column base structure in which a pile member is raised on the ground to be a column member and directly supports a bridge girder. The pile vent type column base structure can reduce the construction cost and can be constructed in a short construction period because the footing can be omitted compared to the direct foundation and the pile foundation. As an example of the pile vent type column base structure, there is an invention described in Patent Document 1. This invention is a three-dimensional structure in which a steel pipe pile and a steel pipe column are inserted and joined, and the steel pipe column and the steel girder are connected via a horizontal girder. This is a ramen-type elevated structure, and is an invention characterized by reducing the beam size by reducing the axial force of the steel beam generated by temperature changes.

JP 2004-156292 A

  The pile-vented column base structure has a small ground resistance area in the horizontal direction of the pile member, so that when horizontal force such as seismic force is applied, the horizontal displacement of the pile member and column member becomes large. It is. In a structure in which a pillow beam is installed on the top of a column member and a bridge girder is installed, a large horizontal displacement occurs during an earthquake, and there is a risk of the bridge girder falling. In addition, in the case of a rigid frame structure that connects a column member and a steel girder, when a seismic force is applied, a large bending moment acts on the base of the column member and the upper part of the pile member. Another problem is that large damage to the column base structure occurs. Moreover, since a big horizontal displacement generate | occur | produces in a pile member and a big deformation | transformation arises in the ground around a pile member, the residual displacement after an earthquake becomes large and it is a subject that repair becomes difficult.

  In particular, when the ground is soft, it is important to suppress the horizontal displacement during an earthquake, so as a measure to suppress the horizontal displacement, the ground improvement that improves the ground strength by injecting cement milk into the soft ground Although the construction method is adopted, the problem is that the ground improvement cost becomes very expensive. Moreover, when sufficient horizontal resistance with respect to a seismic force is insufficient, the construction method which enlarges the cross section of a pile member is employ | adopted. However, since the pile member larger than the shape required from the vertical support force and generated cross-sectional force of the pile member is required, the construction cost of the pile member becomes expensive, and the advantage of the pile vent type column base structure is lost. Is an issue.

  The object of the present invention is to provide a structure that can be constructed at a low cost and in a short period of time by omitting the footing work for the pile vent type column base structure, and is constructed on a particularly soft ground. An object of the present invention is to provide a column base structure having excellent earthquake resistance by improving the horizontal resistance at the time of an earthquake that the conventional pile vent structure has.

In order to solve the above problem, the present invention is configured as follows.
A first aspect of the present invention is a column base structure in which a plurality of pile members constructed in the underground portion are connected to a plurality of column members constructed in the ground portion to support a bridge girder, and the pile members are arranged along the outer surface axial direction. and has connecting joint is secured, between the stake member adjacent to the bridge axis perpendicular, steel underground walls consisting of sheet piles of hat shape having a joint along the side axis direction are arranged, the A coupling joint and a joint of the hat-shaped steel sheet pile are fitted, the pile member and the steel underground wall are connected, and the steel underground wall is composed of a hat-shaped steel sheet pile , A horizontal neutral axis perpendicular to the bridge axis in the pile member is arranged so that a horizontal neutral axis perpendicular to the bridge axis in the hat-shaped steel sheet pile coincides , and the bridge axis in the pile member The connection at a position shifted in the direction of the bridge axis from the right-angled horizontal neutral axis Joint, characterized in that it is fixed.

The second invention is characterized in the first aspect, concrete beams is provided in the upper portion of the front Symbol steel diaphragm wall, that stake member adjacent to the bridge axis perpendicular direction by the beam is coupled And
3rd invention WHEREIN: In the 1st or 2nd invention, in the connection part of the said pile member and a column member, the said pile member is comprised with the steel pipe pile, and the said column member is inserted in the said steel pipe pile. In addition, the gap between the steel pipe pile and the column member is filled with concrete.
A fourth invention is characterized in that, in any one of the first to third inventions, the invention is used in a pile vent type ramen elevated structure.

  The present invention is a structure in which a plurality of pile members arranged in a direction perpendicular to the bridge axis are connected by a steel underground wall, and when a horizontal force such as seismic force is applied, in addition to the ground resistance of the pile members. In addition, since the steel underground wall resists, horizontal displacement is suppressed and safety during an earthquake can be dramatically improved. Since this pile member and steel underground wall are connected via a joint, the load generated in the bridge superstructure is transmitted from the pile member to the steel underground wall via the joint, ensuring horizontal displacement. The effect which suppresses can be exhibited. The steel underground wall can be driven into the ground from the ground by using steel sheet piles, so it is possible to construct a solid steel underground wall for reliable construction. Can be realized. Further, by connecting the steel sheet pile upper portion with the concrete in the direction perpendicular to the bridge axis, it is possible to transmit the load on the steel underground wall, and to transmit the horizontal load evenly to the ground with the steel underground wall. Furthermore, by arranging the pile member and the neutral shaft of the steel ground wall to coincide with each other, it is not necessary to reduce the cross-sectional performance at the joint portion, and the cross-sectional performance of the member can be sufficiently exhibited.

The best mode for carrying out the present invention will be described with reference to the drawings.
FIG. 1 is a front view of a column base structure according to the first embodiment of the present invention, and FIG. 2 is a plan view of an underground portion of the column base structure according to the first embodiment of the present invention. Two pile members 2 are arranged in the ground in a direction perpendicular to the bridge axis, and two pillar members 1 are connected to the upper part of the pile member 2, respectively. It is a bent ramen elevated structure. A coupling joint 4 is fixed in advance along the outer surface axial direction of the pile member 2, and a joint 6 is fixed along the side surface axial direction of the steel underground wall. The coupling joint 4 and the coupling 6 are coupled, and the space between the two pile members 2 in the direction perpendicular to the bridge axis is coupled by a steel underground wall 5.

  FIG. 2 further shows an example of a method for connecting the pile member 2 and the steel underground wall 5. As shown in FIG. 2A, the coupling joint 4 is fixed along the outer surface axial direction of the pile member 2. On the other hand, a joint 6 is fixed to the steel ground wall 5 along the axial direction of both side surfaces of one steel plate. The coupling 4 and the joint 6 of the steel underground wall 5 are fitted, and the pile member 2 and the steel underground wall 5 are connected in the direction perpendicular to the bridge axis. Moreover, FIG. 2 (B) and (C) are the examples which used the steel sheet pile 5a for the steel underground wall. FIG. 2 (B) shows an example using a hat-shaped steel sheet pile 5a, and FIG. 2 (C) shows an example using a straight steel sheet pile 5a. The steel sheet pile has a joint 6 and can be driven from the ground to the ground by connecting to the joint 4 after construction of the pile member, so that a solid steel underground wall 5 can be constructed. It is. FIG.2 (D) has shown the example using the steel earth retaining wall which has a double joint in the steel underground wall 5. FIG. The steel underground wall 5 arranged between the pile members 2 may be a single sheet as shown in FIG. 2 (A), or a plurality of steel sheet piles 5a as shown in FIGS. 2 (B) to (D). May be connected to each other. Further, the grout may be filled in the gap between the coupling joint 4 and the joint 6 of the steel underground wall. In this case, since the load transmission between the pile member 2 and the steel underground wall 5 is ensured, the horizontal resistance can be further improved.

  FIG. 3A is a schematic diagram of the ground resistance of the conventional pile vent type column base structure, and FIG. 3B is a schematic diagram of the ground resistance of the column base structure of the present invention. FIG. 9 shows a side view of the pier structure according to the first embodiment of the present invention. In the conventional pile vent type column bridge structure, the area that resists the horizontal force of the pile member 2 in the ground is only the pile diameter, whereas in the column base structure of the present invention, steel is added in addition to the pile diameter. Since the front surface of the ground wall 5a resists horizontal force, the resistance area is improved. For this reason, when the same horizontal force is applied, the stress generated in the ground can be reduced, so that the horizontal displacement can be reduced.

  When the seismic force acts on the elevated structure, the inertial force of the bridge girder 3 and the column member 2 acts as a horizontal force. This horizontal force is transmitted to the pile member 2 and resists on the ground around the pile member 2. Since the pile member 2 is connected to the steel underground wall 5 via the connecting joint 4 in the direction perpendicular to the bridge axis, the horizontal force of the pile member 2 is connected to the steel underground wall 5 via the connecting joint 4. The ground on the front side of the steel underground wall 5 also resists.

  Here, when the center space | interval of the pile member 2 whose outer diameter is 1 m is arrange | positioned by 7 m, and the pile members 2 are connected with the steel sheet pile 5a, the width | variety of the ground to resist is the conventional pile member 2 It is about 4 times that of the case of only. However, since the resistance area in the depth direction is affected by the bending rigidity of the pile member 2 and the steel sheet pile 5a, when compared with the resistance area of the ground resistance, the resistance area in the depth direction is about 2. 5 times. That is, the horizontal displacement generated at the upper part of the pile portion when the seismic force is applied can be reduced to about 1/2 of the conventional structure.

  FIG. 4 shows a front view of a column base structure according to the second embodiment of the present invention. In this structure, the pillow beam 7 is installed and connected to the upper part of the pillar member 1, and the bridge girder 3 is installed on the upper part of the pillow beam 7 via the support 8. In the conventional elevated structure using a pile vent type column base structure, there is a risk of the bridge girder falling due to the large horizontal displacement at the time of earthquake, but the present invention can improve the horizontal displacement at the time of the earthquake, A support-type elevated structure is also feasible. Furthermore, the upper part of the steel underground wall 5 is integrated by the concrete beam 9, and the adjacent pile members 2 are connected. The horizontal force generated in the column member 1 at the time of the earthquake is transmitted to the pile member 2, but the pile member 2 and the steel underground wall 5 are connected by the concrete beam 9 at the upper part, so the steel underground wall The transmission of the horizontal force to 5 is ensured, and the ground resistance in the horizontal direction is reliably exhibited.

  In addition, the pile member 2 is fixed to a strong support layer in order to secure the support force, but the steel underground wall 5 does not need to be arranged up to the support layer, and the steel underground wall 5 is horizontal. It is only necessary that the ground resistance in the direction is more than the effective range. For example, the length of the steel ground wall may be 1 / β (m) long. Here, β is a characteristic value of the steel underground wall, the horizontal reaction coefficient kh of the ground, the width B of the steel underground wall, the Young's modulus E of the steel underground wall, the cross section of the steel underground wall Using the second moment I, it is calculated by equation (1). Installation cost can be reduced by installing the steel underground wall to the minimum required length.

β = {(kh · B) / (4 · E · I)} ^0.25 (1 / m) (1)

  5 and 6 are front views of a column base structure according to a third embodiment of the present invention. FIG. 5 shows an example applied to a ramen elevated structure, and FIG. 6 shows an example applied to a support type elevated structure. FIGS. 7A to 7C show arrow views (plan views) of VIIA, VIIB, and VIIC in FIG. 5, respectively. When the width of the bridge girder 3 is large, it can be configured to be supported by three or more column members 1. In this case, the pile member 2 is arranged at the same position as the column member 1, and the pile members in one row in the bridge axis direction are connected to each other by the steel underground wall 5 in the underground portion. In this structure, since the horizontal resistance area of the ground can be improved as in the first embodiment, the horizontal displacement during an earthquake can be drastically improved.

  FIG. 8: shows the example of the detailed view of the connection structure of a pile member and a steel underground wall. FIG. 8A is a detailed view of the connection structure when the pile member is the steel pipe pile 2a and the steel underground wall is the hat-shaped steel sheet pile 5a. In the outer surface axial direction of the steel pipe pile 2a, a coupling joint 4a to be fitted to the joint 6 of the steel sheet pile 5a is fixed in advance. After construction of the steel pipe pile 2a, the coupling joint 4a and the joint 6 of the steel sheet pile 5a are fitted and connected. Since the coupling joint 4a is a joint that fits with the joint 6 of the steel sheet pile 5a, the gap between the joints can be reduced, and the pile member and the steel underground wall can be firmly coupled. .

  By the way, when the neutral axis in the bridge axis direction of the steel pipe pile 2a and the neutral axis in the bridge axis direction of the steel sheet pile 5a do not coincide with each other, the transmission of the shearing force in the coupling joint 4a is insufficient. The cross-sectional performance of the steel sheet pile 5a is not sufficiently exhibited. Therefore, in FIG. 8A, the coupling joint 4a is arranged so that the neutral axis 11 of the steel pipe pile 2a in the bridge axis direction and the neutral axis 12 of the steel sheet pile 5a coincide with each other. With such a structure, no shear force is generated between the coupling joint 4a and the steel underground wall joint 6, so that the cross-sectional performance of the steel pipe pile 2a and the steel underground wall 5a is sufficiently exhibited. Can resist the horizontal force efficiently.

  FIG. 8B shows a detailed view of another connecting structure. A small-diameter steel pipe joint 4b provided with a slit in the axial direction along the outer surface axial direction of the steel pipe pile 2a is fixed in advance. The slit width is set to be larger than the thickness of the steel sheet pile 5a and smaller than the joint 6 of the steel sheet pile 5a. It is the structure where the joint part of the steel sheet pile 5a was fitted and connected through the slit of the coupling joint 4b after construction of the steel pipe pile 2a. By using a small diameter steel pipe joint having a slit, construction errors can be absorbed. In this connection structure, when the fitting margin at the joint becomes excessive, the coupling joint 4b can be firmly connected by filling with cement or the like.

  Although the pile member 2 shown in FIG. 8 showed the case of the steel pipe pile 2a, the pile member 2 may be steel piles other than a steel pipe pile, or a concrete pile. In the case of a steel pile, the coupling joint can be connected by welding or the like. In the case of a pile made of concrete, it is possible to connect by placing a connecting material separately in the connecting joint and embedding it in the axial direction of the concrete pile. Furthermore, although the steel underground wall shown in FIGS. 8A and 8B shows an example of a hat-shaped steel sheet pile 5a, a U-shaped steel sheet pile as shown in FIG. The steel underground wall of another shape shown to 2 (A), (C), (D) may be sufficient.

  FIG. 10 shows a detailed view of the connection structure between the pile member and the column member. When the column member and the pile member are made of steel and have the same outer diameter, they can be connected by welding on site. Moreover, when the column member and the pile member are made of concrete, the reinforcing members of the pile member and the reinforcing members of the column member are connected by lap joints, and can be connected on the spot by filling concrete. FIG. 10A shows a connection structure when the pile member 2 is a steel pipe pile 2a and the column member 1 is made of concrete. The steel pipe pile 2a has a structure in which a concrete column rebar 13 is inserted into the upper space of a predetermined length, and a concrete 14 is filled in the gap. In this case, it is more desirable if a stopper (not shown) is disposed on the inner peripheral surface of the steel pipe pile 2a, because load transmission from the reinforcing bar to the steel pipe is ensured.

  FIG. 10 (B) shows the steel pipe pile 2 a and the steel pipe column 1, and shows a connection structure when the outer diameter of the steel pipe pile 2 a is larger than the outer diameter of the steel pipe column 1. The lower end portion of the steel pipe column is inserted into the upper space of the steel pipe pile 2a for a predetermined length, and the connection space is filled with concrete 14 and connected. In this case, if a stopper (not shown) is arranged on the outer peripheral surface of the steel pipe column 1 and the inner peripheral surface of the steel pipe pile 2a in the connection section, the load transmission from the steel pipe column 1 to the steel pipe pile 2a is ensured. This is still desirable.

  Moreover, in the connection structure of FIG.10 (B), the connection structure in case the outer diameter of the steel pipe pile 2a is larger than the outer diameter of the steel pipe pillar 1 is shown. In this case, since the ground resistance area of the steel pipe pile when the seismic force is applied is increased, the horizontal displacement of the column base structure is suppressed. Furthermore, the bending member generated when the seismic force is applied to the viaduct structure is larger in the pile member than in the column member. Therefore, by increasing the outer diameter of the pile member, it becomes a structure in which the bending strength of the pile member is larger than the bending strength of the column member, which is also desirable from the viewpoint of earthquake resistance.

  FIG. 11 shows a construction procedure diagram according to the first embodiment of the present invention. First, in FIG. 11 (A), the pile member 2 in which the coupling joint 4 is disposed along the side surface axial direction is built in the ground. In FIG. 11 (B), the steel underground wall 5 is driven in the ground so that the joint of the steel underground wall 5 is connected to the connecting joint 4 in the direction perpendicular to the bridge axis of the pile member 2. To do. In FIG. 11C, the column member 1 is disposed on the top of the pile member 2, and the pile member 2 and the column member 1 are connected. In FIG. 11 (D), the bridge girder 3 is arranged on the upper part of the column member 1.

It is a front view of the column base structure concerning a 1st embodiment of the present invention. It is a top view in the underground part of the column base structure which concerns on the 1st Embodiment of this invention. It is explanatory drawing of the ground resistance of the horizontal direction which concerns on a prior art and this invention. It is a front view of the column base structure concerning the 2nd Embodiment of this invention. It is a front view of the column base structure concerning other embodiments of the present invention. It is a front view of the column base structure concerning other embodiments of the present invention. It is a top view of the column base structure which concerns on embodiment of FIG. It is a top view which concerns on the connection structure of the pile member of this invention, and a steel underground wall. It is a side view of the column base structure concerning a 1st embodiment of the present invention. It is a side view of the connection structure of the pillar member and pile member of the present invention. It is a construction procedure figure of the column base structure concerning a 1st embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Column member 2 Pile member 2a Steel pipe pile 3 Bridge girder 4 Coupling joint 4a Example of coupling joint 4b Another example of coupling joint 5 Steel underground wall 5a Steel sheet pile 6 Joint 7 Pillow beam 8 Bearing 9 Concrete beam 11 Pile Neutral shaft 12 Steel neutral wall 13 Steel rebar 14 Concrete

Claims (4)

In the column base structure that supports the bridge girder by connecting the multiple pile members built in the underground part with the multiple pillar members built in the ground part,
Wherein the stake member are fixed the coupling joint along the outer surface direction, between the stake member adjacent to the bridge axis perpendicular, made of steel sheet pile hat shape having a joint along the side axis A steel underground wall is arranged, the coupling joint and the joint of the hat-shaped steel sheet pile are fitted, and the pile member and the steel underground wall are connected ,
A horizontal neutral axis perpendicular to the bridge axis in the pile member is arranged so that a horizontal neutral axis perpendicular to the bridge axis in the hat-shaped steel sheet pile coincides , and the bridge axis in the pile member The column base structure , wherein the coupling joint is fixed at a position shifted in a bridge axis direction from a right-angled horizontal neutral axis .   The column base structure according to claim 1, wherein a concrete beam is provided on an upper portion of the steel underground wall, and pile members adjacent in the direction perpendicular to the bridge axis are connected by the beam.   In the connecting portion between the pile member and the column member, the pile member is formed of a steel pipe pile, the column member is inserted into the steel pipe pile, and concrete is formed in a gap between the steel pipe pile and the column member. The column base structure according to claim 1, wherein the column base structure is filled. The column base structure according to any one of claims 1 to 3, wherein the column base structure is used in a pile bent type ramen elevated structure.

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