JP5215640B2 - Anti-vibration foundation structure - Google Patents

Description

  The present invention relates to an anti-vibration foundation structure for isolating a foundation of a structure supported by a supporting ground.

    As shown in FIG. 6, the vibration G1 of the support ground 10 at the time of the earthquake tends to be propagated to the ground surface even if it is small on the support ground 10 but amplified on the upper surface ground 16 (vibration G2). . Therefore, in many structures 18, the steel pipe pile 11 that supports the foundation 22 of the structure 18 is made to reach the support ground 10 and the foundation 22 is supported by the support ground 10 in order to prevent damage due to an earthquake.

  However, even in such a configuration, since the steel pipe pile 11 and the foundation 22 are in direct contact with the surface layer ground 16, the vibration at the time of earthquake propagated to the structure 18 is affected by the vibration G 2 of the surface layer ground 16. It cannot be blocked.

  As shown in FIG. 7, the surface ground 16 has vibrations K <b> 1 that occur in daily living environments such as traveling vibrations of vehicles 68, trains, etc., and driving vibrations of machinery. The ground surface vibration K1 is attenuated by the distance (vibration K2) on the ground surface while diffusing, and is attenuated (vibration K3) by the characteristic S determined by the geology in the depth direction in the ground.

  Furthermore, when the excitation source is close, the vibration of the surface ground 16 propagates to the structure 18 via the steel pipe pile 11 and the foundation 22 of the structure 18 that are in direct contact with the surface ground 16.

  For this reason, in structures (such as precision equipment manufacturing factories and concert halls) that are equipped with anti-vibration equipment that dislikes vibrations such as precision equipment, this occurs not only in the earthquake vibration G1 and G2, but also in daily living environments. There is a need for a technique for blocking the propagation of vibrations K2 and K3 to the structure 18.

  As a technique for blocking the vibration of the surface ground to the structure, for example, a technique is disclosed in which a steel pipe pile supporting the structure is a double steel pipe pile (see Patent Document 1).

  That is, as shown in FIGS. 8 (a) and 8 (b), in the double steel pipe pile, the structure is supported by the inner foundation pile 1 and the outer circumference of the inner foundation pile 1 and the inner circumference of the outer outer pipe 3. A clearance 4 is formed between the surface and the surface, and the clearance 4 prevents the vibration of the surface ground from propagating to the structure through the internal foundation pile 1. At this time, a stopper 2 is provided above the clearance 4 to avoid collision and damage due to vibration during an earthquake or the like.

  However, in Patent Document 1, when the clearance 4 is increased, the foundation pile 1 rolls and vibrates in the lateral direction within the range of the clearance 4, and the structure also vibrates. On the other hand, if the clearance 4 is reduced, the contact time between the stopper 2 and the outer tube 3 increases, and there is a problem that vibration propagates to the structure via the stopper 2.

Furthermore, since the stopper 2 of Patent Document 1 is provided in a narrow gap between the foundation pile 1 and the outer pipe 3, maintenance at the time of mounting and replacement is troublesome, and a work space for them is provided in the building. Must be provided separately under the floor.
JP-A-8-13529

  This invention considers the fact concerned, and makes it a subject to provide the anti-vibration foundation structure which reduces the vibration of the foundation of the structure supported by the steel pipe pile reached to the support ground.

  The anti-vibration foundation structure according to claim 1 is a support member for supporting a foundation of a structure on a support ground in a lower layer of the surface layer ground in a state where the edge of the structure is cut off from the surface layer ground, and the support member And a cylindrical member surrounding the support member, and vibration reducing means provided on the foundation for reducing vibration of the foundation.

  In the invention according to claim 1, the foundation of the structure is supported by the support member on the support ground in a state where the edge is cut from the surface layer ground. For this reason, propagation of vibration from the surface ground to the foundation can be blocked.

At this time, the support member that supports the foundation is provided with a cylindrical member that surrounds the support member with a predetermined gap from the support member. For this reason, the propagation of vibration from the surface layer ground to the support member can be blocked.
The foundation is provided with vibration reducing means for reducing the vibration of the foundation. As a result, it is possible to reduce vibration that is slightly present in the support ground and is amplified and propagated to the foundation through the support member.

  According to a second aspect of the present invention, in the vibration-isolating foundation structure according to the first aspect, the vibration reduction means is provided on the foundation, and vibration detection means for detecting the direction, frequency and amplitude of the vibration of the foundation. An excitation means for reducing the foundation vibration by generating an excitation force, and a control means for controlling the excitation force generated by the excitation means based on the output of the vibration detection means. It is a feature.

In the invention according to claim 2, the vibration reducing means detects the direction, frequency and amplitude of the vibration of the base portion with the vibration detecting means, and generates the excitation force with the vibration means provided in the base portion. Reduce the vibration of the part. The control means controls the excitation force generated by the excitation means based on the output of the vibration detection means.
As a result, the vibration slightly present in the supporting ground is amplified via the supporting member, and the vibration transmitted to the foundation can be reduced by the excitation means.

The invention described in claim 3 is characterized in that, in the vibration-isolating foundation structure according to any one of claims 1 and 2, the vibration reducing means is disposed below the foundation.
Thereby, a vibration reduction means can be arrange | positioned, without impairing the space of the upper part of the foundation in which a structure is mounted.

  According to a fourth aspect of the present invention, in the vibration-isolating basic structure according to any one of the second or third aspects, the vibration generating means generates a vibration force in the X-axis direction, and the base X-axis An X-axis vibration device that reduces vibrations in the direction, and a Y-axis vibration device that generates a vibration force in the Y-axis direction and reduces vibrations in the Y-axis direction of the foundation.

According to a fourth aspect of the present invention, the vibration generating means generates a vibration force in the X-axis direction with the X-axis vibration device, reduces the vibration in the X-axis direction of the base portion, and the Y-axis vibration device. A vibration force in the Y-axis direction is generated to reduce vibration in the Y-axis direction of the base portion.
As a result, the vibration in the X-axis direction and the vibration in the Y-axis direction that are propagated from the support ground to the foundation via the support member can be reduced.

  The invention according to claim 5 is the vibration-isolating foundation structure according to any one of claims 1 to 4, wherein the support member is a hollow steel pipe pile, a solid steel pipe pile in which the steel pipe is filled with concrete. Or it is a concrete pile, The said cylindrical material is a hollow steel pipe which the lower end part is closed and contacts with the outer periphery of the said steel pipe pile or the said concrete pile.

  In invention of Claim 5, it is set as the double pile structure with a steel pipe pile or a concrete pile, and a hollow steel pipe, the lower end part of a hollow steel pipe is closed, and is contacting with the outer periphery of a steel pipe pile or a concrete pile. In addition, the concrete pile includes not only a precast concrete pile but also a concrete pile constructed on site.

  As a result, it is possible to prevent the vibration of the surface ground from propagating to the steel pipe pile by the predetermined gap provided between the inner steel pipe pile or the concrete pile and the outer hollow steel pipe, which has a double pile structure. . Moreover, the lower end part of an outer hollow steel pipe is closed, and it prevents water from entering from the lower end part into a predetermined gap between the inner steel pipe pile or the concrete pile and the outer hollow steel pipe. As a result, the effect of blocking the vibration of the surface ground can be maintained.

  Since this invention set it as the said structure, the vibration of the foundation of the structure supported by the steel pipe pile reached to the support ground can be reduced.

  As shown in FIG. 1B, a steel pipe pile 12A as a support member is driven into the support ground 10 in the lower layer of the surface ground 16.

The steel pipe pile 12A may be either a hollow steel pipe pile, a solid steel pipe pile in which the steel pipe is filled with concrete, or a concrete pile.
The upper end portion of the steel pipe pile 12A is joined to the bottom surface of the vibration isolation foundation 72, which is a foundation for reducing the vibration of the structure, and supports the vibration isolation foundation 72.

  The anti-vibration foundation 72 is a flat plate of concrete, and is supported by steel pipe piles or concrete piles 12A, 12B, 12C, 12D at four corners, and a precision machine 37 as a structure is placed thereon. These steel pipe piles or concrete piles have the same configuration, and the steel pipe pile or concrete pile 12A will be described below as a representative.

  The anti-vibration foundation 72 is disposed at a predetermined interval in the maintenance pit 20 that is a box-shaped concrete body formed by digging down the surface layer ground 16. The anti-vibration foundation 72 is cut off from the surface layer ground 16 by a maintenance pit 20 provided for inspection of a vibration device or the like, which will be described later, or for enabling the foundation to be anti-vibration.

  The steel pipe pile or the concrete pile 12 </ b> A is surrounded by the tubular material 14 over the entire range in the depth direction of the surface layer ground 16, thereby forming a double steel pipe pile 13. A gap d is provided between the outer peripheral surface of the inner steel pipe pile or concrete pile 12 </ b> A and the inner peripheral surface of the outer cylindrical member 14, which is a double steel pipe pile 13.

The tubular member 14 is formed of a hollow steel pipe, the lower end portion is in contact with the upper layer of the support ground 10, and a ring-shaped blocking member 27 is provided in the gap d at the lower end portion in contact with the support ground 10. Since the gap d at the lower end is closed by the closing member 27, water cannot enter the gap d, and the gap d is maintained.
In addition, when installing the closing member 27, the steel pipe pile as a support member or the concrete PCa pile as a kind of the concrete pile 12A is a pre-made pile. The heavy steel pipe pile 13 is provided at a predetermined position.
On the other hand, in the case of a cast-in-place concrete pile which is a kind of concrete pile 12A, a cylindrical tube (for example, a rubber tube or a flexible resin tube) having a diameter capable of forming a gap d inside the tubular member 14 is used as a steel pipe pile. Alternatively, it is used in place of the concrete pile 12A and provided at a predetermined position when the double steel pipe pile 13 is formed on the ground. And after building in the said double steel pipe pile 13, concrete is laid and it is set as a field cast concrete pile.
In any of the double steel pipe piles 13, a known water-stopping material (for example, a silicon-based sealing material) is applied to a joint portion between members such as a pile-side outer peripheral surface and a hollow steel pipe-side inner peripheral surface of the closing member 27. It is preferable to further improve the water stoppage of the closing member 27.

  The upper end portion of the tubular material 14 is in contact with the back surface of the floor 20F of the maintenance pit 20. Further, the steel pipe pile 12A passes through a through hole 31 formed in the maintenance pit 20 (not in contact with the through hole 31), and supports a vibration isolation foundation 72 in the maintenance pit 20.

  By adopting such a configuration, the tubular material 14 separates the steel pipe pile or the concrete pile 12A from the surface layer ground 16 with a gap d, and water is not submerged in the gap d, and vibration of the surface layer ground 16 is generated. Propagation to the steel pipe pile or concrete pile 12 can be blocked. Thereby, the vibration propagated from the surface layer ground 16 to the anti-vibration foundation 72 via the steel pipe pile or the concrete pile 12A can be cut off.

However, since the intermediate part of the steel pipe pile or the concrete pile 12A is not in contact with the tubular material 14, it can swing in the lateral direction. As a result, a slight vibration of the support ground 10 is amplified at the resonance point of the steel pipe pile or the concrete pile 12 </ b> A, and a low frequency vibration is propagated to the vibration isolation foundation 72 in the lateral direction.
The vibration characteristics of the low frequency in the transverse direction transmitted to the vibration isolation foundation 72 are calculated by modeling the vibration isolation foundation 72 as a vibration system that supports the four corners with the steel pipe piles or the concrete piles 12A, 12B, 12C, 12D. Can do. That is, the spring constant for supporting the vibration isolation foundation 72 is determined from the values of the material, length, outer diameter, etc. of the steel pipe pile or concrete pile 12A, and the vibration characteristics of the vibration isolation foundation 72 can be obtained.
Next, a means for reducing the lateral vibration transmitted to the vibration isolation foundation 72 will be described.

  As shown in FIG. 1B, floor concrete 17 is placed around the maintenance pit 20, and a building 35 (not shown) is built on the floor concrete 17. A precision machine 37 is accommodated in the building 35 and placed on a vibration isolation foundation 72.

  On the lower surface of the vibration isolation foundation 72, vibration reducing means 24 for reducing the vibration in the lateral direction of the vibration isolation foundation 72 is provided. The vibration reducing means 24 generates a lateral excitation force based on the calculated vibration characteristics of the vibration isolation foundation 72, and applies the generated excitation force to the vibration isolation foundation 72 in a direction to cancel the vibration. The vibration of the vibration foundation 72 is reduced.

  Specifically, as shown in FIG. 1A, the vibration reducing means 24 includes an X-axis vibration device 25 as a vibration means for generating a vibration force in the X-axis direction, and a vibration force in the Y-axis direction. It has the Y-axis vibration device 26 as a vibration means to be generated, and is arranged at a position where two each face each other.

  The X-axis vibration device 25 applies an exciting force in the X-axis direction between the steel pipe pile or concrete pile 12A and the steel pipe pile or concrete pile 12B and between the steel pipe pile or concrete pile 12C and the steel pipe pile or concrete pile 12D. Arranged to do.

The Y-axis vibration device 26 has the same configuration as the X-axis vibration device 25, and is between the steel pipe pile or concrete pile 12B and the steel pipe pile or concrete pile 12C, and between the steel pipe pile or concrete pile 12D and the steel pipe pile or concrete pile 12A. In between, it is arranged so that the excitation force acts in the Y-axis direction.
A vibration sensor 28 as vibration detecting means and a control device 30 as control means are provided on the lower surface of the vibration isolation foundation 72.

With this configuration, the vibration sensor 28 detects the vibration of the vibration isolation base 72 and outputs the detected vibration information to the control device 30. The control device 30 calculates the magnitude and timing of the vibration force generated by the X-axis vibration device 25 and the Y-axis vibration device 26 based on the detection result of the vibration sensor 28, and the X-axis vibration device 25 and the Y-axis. The vibration is output to the vibration device 26.
Although the vibration sensor 28 for detecting the vibration of the vibration isolation foundation 72 has been described, in addition to this, although illustration is omitted, for example, a vibration sensor for detecting the vibration of the steel pipe pile or the concrete pile 12A or the floor concrete 17 is provided, Finer control can be performed using these detection results.

The X-axis vibration device 25 and the Y-axis vibration device 26 generate vibration forces in the X-axis direction and the Y-axis direction based on the control signal input from the control device 30.
Next, the X-axis vibration device 25 will be described. The Y-axis vibration device 26 has the same configuration and will not be described.

  As shown in FIG. 2, two rails 32 are linearly provided in parallel on the lower surface of the vibration isolation foundation 72. The rail 32 has a length that secures the moving distance of the X-axis vibration device 25 and is disposed in the X-axis direction.

  The rail 32 is formed in an L-shape in cross-sectional view, and the flange portion 32U bent at the upper end is fixed to the lower surface of the vibration isolation base 72 with a bolt 33, and the cross-sectional view lowered from the upper end portion 32U by a predetermined amount is an L-shape. The part is formed by bending a passage 32F that has a flat part in the horizontal direction and travels a wheel.

  The two rails 32 are arranged at positions where the heights of the passages 32F are the same with the sides on which the passages 32F are formed facing inward. In the two passages 32F, drive wheels 38 and driven wheels 36 attached to both side surfaces of the X-axis vibration device 25 are movably accommodated.

The drive wheels 38 are connected to both ends of the drive shaft 40 that transmits the drive force from the drive source, and the drive wheels 38 are rotated in the same direction by the rotation of the drive shaft 40.
The drive shaft 40 is located in the center in the front-rear direction of the X-axis vibration device 25 and is disposed in a direction orthogonal to the rail 32. The drive shaft 40 is rotatably attached to the frame 34 of the X-axis vibration device 25.

A gear portion 42 that converts the rotation of the driving force into the rotation of the drive shaft 40 is provided at the center of the drive shaft 40. A driving force is transmitted to the gear portion 42 from a motor 44 as a power source.
Electric power is supplied to the motor 44 from a power source (not shown), and a command for the rotation direction (traveling direction R) and rotation speed of the motor 44 is sent from the control device 30.

  On both sides of the driving wheel 38 in the front-rear direction, driven wheels 36 are rotatably attached to the frame 34 of the X-axis vibration device 25.

  A weight 46 is attached to the frame 34 as a mass for generating a required excitation force. The weight 46 is formed by overlapping steel plates, and is attached to the frame 34 with bolts 48 in two places before and after the motor 44. Thereby, mass can be increased / decreased by increasing / decreasing the number of steel plates according to the required excitation force.

With such a configuration, the motor 44 is controlled by a command from the control device 30, the moving speed of the X-axis vibration device 25 is controlled by the rotation of the motor 44, and the necessary acceleration is generated in the X-axis vibration device 25. Can be made.
Although the example in which the X-axis vibration device 25 is arranged on the lower surface of the vibration isolation base 72 has been described, a reinforcing member (not shown) is used to prevent the X-axis vibration device 25 from moving relative to the vibration isolation foundation 72. A structure in which the suspension end portion is reinforced and suspended below the vibration isolation base 72 may be employed.

Here, the trial calculation result of the vibration reduction amount of the steel pipe pile 11 which is not made into the double steel pipe pile structure and the double steel pipe pile 13 performed for the effect verification of the double steel pipe pile structure is demonstrated.
First, the vibration reduction amount in the case of the double steel pipe pile 13 will be described with reference to FIG.
In FIG. 3, the horizontal axis represents frequency (Hz), and the vertical axis represents displacement amplitude (μm / sec), velocity amplitude (cm / sec), and acceleration amplitude (cm / sec ² ), respectively.

  As the trial calculation conditions, the surface ground 16 is a soft ground, and the thickness of the surface ground 16 is 10 m. The diameter of the cylindrical material 14 was 1200 mm, the diameter of the steel pipe pile 12A was 800 mm, and the response when each vibration input of 1 to 50 Hz was given to the surface layer ground 16 was obtained. The vibration of the foundation 22 supported by the conventional steel pipe pile 11 is indicated by a white circle, and the vibration of the vibration-isolating foundation 72 supported by the double steel pipe pile 13 is indicated by a black circle.

  As shown in FIG. 3, at a frequency of 10 Hz, for example, the foundation 22 supported by the conventional steel pipe pile 11 shown in FIG. 10 vibrates with a velocity amplitude of 0.006 (cm / sec). On the other hand, the vibration isolation foundation 72 supported by the double steel pipe pile 13 shown in FIG. 1 vibrates at a velocity amplitude of 0.0015 (cm / sec) at a frequency of 10 Hz. Thus, by setting it as the double steel pipe pile 13, compared with the conventional steel pipe pile 11, a speed amplitude reduces to 1/4.

That is, if the resonance point of the double steel pipe pile 13 is set near 10 Hz, the vibration can be reduced to ¼ in the double steel pipe pile 13 as compared with the conventional steel pipe pile 11.
Next, a method for reducing the vibration of the vibration isolation foundation 72 by attaching the X-axis excitation device 25 to the vibration isolation foundation 72 supported by the double steel pipe pile 13 will be described.

  As shown in FIG. 4, in a state where no control is performed, the vibration isolation foundation 72 vibrates with a vibration wave P (amplitude a, frequency 1 / T) indicated by a solid line in the X-axis direction at the resonance point of the double steel pipe pile 13. To do. The vibration sensor 28 detects the vibration wave P and transmits a detection result to the control device 30.

The control device 30 calculates a vibration wave Q for canceling the vibration wave P. As indicated by a broken line, the vibration wave Q has a period shifted from the vibration wave P by ½ period, and the amplitude a and the frequency 1 / T are the same vibration waves as the vibration wave P.
From the calculation result, the control device 30 outputs a control signal to the X-axis vibration device 25 so as to generate the vibration wave Q (amplitude a, vibration frequency 1 / T, period 1/2 delay).

  The X-axis vibration device 25 receives the control signal and rotates the motor 44 in a predetermined direction until a predetermined rotation speed is reached. Thereby, the drive shaft 40 and the drive wheel 38 rotate, and the X-axis vibration device 25 on which the weight 46 is mounted moves. By controlling the moving speed and moving direction of the weight 46, a vibration wave Q in the X-axis direction is generated. At this time, the amplitude a is adjusted by the moving amount of the weight 46, and the period T is adjusted by the switching timing of the moving direction.

  As shown in FIG. 4, when this vibration wave Q is applied to the vibration isolation foundation 72, the vibration wave P in the X axis direction propagated to the vibration isolation foundation 72 is canceled out, and the vibration of the vibration isolation foundation 72 in the X axis direction is canceled. Is reduced. At this time, although the vibration reduction performance varies depending on the characteristics of the vibration wave Q generated by the X-axis vibration device 25, the amplitude can be reduced to ½ of the vibration wave P from the past results (vibration without control). 1/8 of that).

  Here, as shown in FIG. 5, the above-described results can be summarized as follows. In the horizontal direction, the double steel pipe pile 13 vibrates in comparison with the one without the conventional vibration reduction means (only the steel pipe pile 11). Can be reduced to ¼. Further, by using this X-axis vibration device 25, 1/2 of the vibration can be reduced. Therefore, as a result, vibration can be reduced to 1/8.

On the other hand, although the trial calculation process is omitted in the vertical direction, the vertical force that the steel pipe pile 12 receives from the surface ground 16 can be cut off by using the double steel pipe pile 13 of the configuration B. Thereby, compared with the steel pipe pile 11 of the structure A, a vibration reduces to 1/3. However, even if the X-axis vibration device 25 of the configuration C is added to the configuration B, there is no vertical vibration reduction effect, so that the vibration cannot be reduced to 1/3.
Although the embodiments have been described above, the present invention is not limited to the above-described embodiments, and various embodiments can be adopted without departing from the gist of the present invention.

It is a figure which shows the vibration proof foundation structure which concerns on the 1st Embodiment of this invention. It is a figure which shows schematic structure of the X-axis vibration apparatus which concerns on the 1st Embodiment of this invention. It is a figure which shows the trial calculation result of the vibration reduction amount of the double steel pipe pile and steel pipe pile which concern on the 1st Embodiment of this invention. It is a figure which shows the principle of the vibration reduction of the vibration reduction means which concerns on the 1st Embodiment of this invention. It is a figure which shows the vibration reduction effect of the anti-vibration foundation structure which concerns on the 1st Embodiment of this invention. It is a figure which shows the conventional anti-vibration foundation structure. It is a figure which shows the conventional anti-vibration foundation structure. It is a figure which shows the conventional anti-vibration foundation structure.

Explanation of symbols

10 Support ground 12 Support member (hollow steel pipe pile, solid steel pipe pile, concrete pile)
14 Tube material (hollow steel pipe)
16 Surface layer 22 Structure foundation 24 Vibration reduction means (two-dimensional vibration reduction means)
25 Excitation means (X-axis excitation device)
26 Excitation means (Y-axis excitation device)
27 Closure member 28 Vibration detection means (vibration sensor)
30 Control means (control device)
72 Foundations of structures (anti-vibration foundations)

Claims (5)

A support member for supporting the foundation of the structure on a support ground in a lower layer of the surface ground in a state where the edge of the surface ground is cut;
A cylindrical member surrounding the support member with a predetermined gap between the support member and
Vibration reducing means provided on the foundation for reducing vibration of the foundation;
An anti-vibration foundation structure characterized by comprising: The vibration reducing means includes
Vibration detecting means for detecting the direction, frequency and amplitude of the vibration of the foundation;
An excitation means provided on the foundation to reduce the vibration of the foundation by generating an excitation force;
Control means for controlling the excitation force generated by the excitation means based on the output of the vibration detection means;
The anti-vibration foundation structure according to claim 1, wherein:   The vibration isolation foundation structure according to claim 1, wherein the vibration reducing means is disposed below the foundation. The vibration means is
An X-axis vibration device that generates a vibration force in the X-axis direction and reduces vibration in the X-axis direction of the foundation;
A Y-axis vibration device that generates a vibration force in the Y-axis direction and reduces vibrations in the Y-axis direction of the foundation;
The anti-vibration foundation structure according to any one of claims 2 and 3, characterized by comprising:   The support member is a hollow steel pipe pile, a solid steel pipe pile or concrete pile filled with concrete in the steel pipe, and the tubular member is closed at the lower end, and comes into contact with the outer circumference of the steel pipe pile or the concrete pile. It is a hollow steel pipe, The vibration proof foundation structure of any one of Claims 1-4 characterized by the above-mentioned.

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