Vibration reduction mechanism and vibration reduction method

Abstract

To provide a vibration reduction mechanism and a vibration reduction method capable of reducing vibrations generated in construction work without requiring a huge mechanism or a large cost.SOLUTION: The present invention comprises a pile body 3 comprising an embedded portion 31 provided between a vibration generation location 2 and a vibration failure prevention location 11 on the propagation path of the vibration generated from the vibration generation location 2, and embedded up to the support ground 92 and reduces the peripheral frictional force of the peripheral surface portion, and a pile head 32 located on the ground surface, a pedestal 6 comprising first pedestal members 4, 4 formed of steel and arranged close to both sides of the pile body 3 in the front view on the ground surface, a second pedestal member 5 which is arranged above the first pedestal members 4, 4 and is formed of steel, and a rotational inertia mass damper 7 arranged between the pile body 3 and the second pedestal member 5 between the first pedestal members 4, 4, whose upper end is connected to the second pedestal member 5 and whose lower end is connected to the pile head 32.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a vibration reduction mechanism and a vibration reduction method. [Background technology]

[0002] The vibration frequencies of work noises generated by construction work are mainly in the range of 4 to 16 Hz, and because this frequency range is so wide, it is a cause of vibration disorders in the vicinity of the work site and complaints about the work site from the surrounding area. Demolition work and piling work, etc., cause large vibrations with low frequencies of 4 to 8 Hz, while the passage of heavy construction machinery and construction vehicles causes vibrations with high frequencies of 8 to 16 Hz for long periods of time. Countermeasures against the above-mentioned vibrations include laying old tires, vibration-proof mats, steel plates, etc. on the roads on which heavy construction machinery runs at construction sites, installing vibration-proof trenches or steel sheet piles (vibration-proof walls) on the ground surface in the propagation path of the vibration waves, and piling up embankments and sandbags around the edges of construction sites.

[0003] However, the method of laying old tires, vibration-proof mats, steel plates, etc., has the problem that it can only deal with vibrations caused by moving heavy construction machinery and construction vehicles, and cannot deal with vibrations caused by construction work, etc. The method of installing vibration-proof trenches has the problem that even if a large protective trench with a depth of about 10 m is installed, it can only reduce vibrations by an average of about 5 dB in the high frequency range. The method of installing steel sheet piles has the problem that the installation costs of steel sheet piles are high, making the construction uneconomical. Furthermore, the method of piling up embankments and sandbags has problems with the construction costs and installation space. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2017-115476 A [Patent Document 2] Patent No. 6785535 [Patent Document 3] JP 2016-23516 A Summary of the Invention [Problem to be solved by the invention]

[0005] On the other hand, in order to address the various problems associated with the above-mentioned conventional vibration countermeasures, there is a method of laying weights, sandbags, etc. at predetermined positions between the vibration source and the object for which vibration is to be reduced, as a method of suppressing the costs required for implementing the countermeasures and ensuring the desired vibration reduction effect (see, for example, Patent Documents 1 and 2). However, while the above-mentioned method is effective in reducing vibration in the high frequency range of 11 Hz or higher, it has the problem that it is almost ineffective in the low frequency range of 4 to 8 Hz.

[0006] As a method for reducing vibrations in the low frequency range mentioned in the above problem, there is a method of providing a foundation supported by piles on the vibration transmission path, and a spring-supported weight is placed on the foundation to provide a Tuned Mass Damper (TMD) dynamic vibration absorber (see Patent Document 3). In this method, the natural frequency (the specifications of the spring and weight) of the TMD dynamic vibration absorber is adjusted so as to resonate with the frequency of the vibration wave to be reduced, thereby achieving the effect of blocking the propagation of vibration waves at any frequency. However, the above method has a problem that the mass of the weight needs to be increased in order to increase the vibration reduction effect. In addition, since the TMD dynamic vibration absorber, which is composed of one weight and multiple springs supporting it, can reduce vibrations at only one target frequency, there is also a problem that a large installation space is required to install multiple TMD dynamic vibration absorbers in order to reduce multiple frequencies. There is also a problem that the cost of adjusting the mass of the weight and securing the installation space for the TMD dynamic vibration absorber increases, making this method uneconomical.

[0007] In recent years, rotary inertia mass dampers have been used as vibration damping devices, which convert linear displacement (axial displacement) into rotation using a ball screw to rotate a weight and obtain inertial resistance. The rotary inertia mass damper has the characteristic that, with the above mechanism, it can provide a large inertial mass that is hundreds to thousands of times the mass of the weight to be rotated, despite its compact configuration.

[0008] The present invention has been made in consideration of the above-mentioned circumstances, and aims to provide a vibration reduction mechanism and a vibration reduction method that can reduce vibrations generated in construction work without requiring a huge mechanism or significant cost. [Means for solving the problem]

[0009] In order to achieve the above-mentioned object, the vibration reduction mechanism of the present invention comprises: a pile body that is provided between a vibration generating point and a vibration disturbance prevention point, and that has an embedded portion that is embedded into the supporting ground to reduce the peripheral friction force of the peripheral portion, and a pile head that is located on the ground surface; a mounting that includes: a first mounting member formed of steel and positioned adjacent to both sides of the pile body on the ground surface when viewed from the front; and a second mounting member formed of steel and positioned on top of the first mounting member; and a rotational inertia mass damper that is positioned between the pile body and the second mounting member between the first mounting members, and that has an upper end connected to the second mounting member and a lower end connected to the pile head.

[0010] The above configuration makes it possible to provide a vibration reduction mechanism consisting of the frame, pile, and rotary inertial mass damper, which does not require a huge weight or a mechanism to handle multiple vibration frequencies. Therefore, the vibration system consisting of the inertial mass of the rotary inertial mass damper and the vertical rigidity of the pile and frame functions in the same way as a TMD dynamic vibration absorber, without requiring a huge mechanism or significant costs, making it possible to obtain the desired vibration reduction effect against vibrations generated from vibration generating points.

[0011] Furthermore, the vibration reduction mechanism according to the present invention may further comprise a weight provided on an upper portion of the second frame member for carrying an upper load.

[0012] The above-mentioned configuration can achieve the same effect as the conventional method of loading sandbags or weights on the ground surface. Therefore, the vibration reduction mechanism can further improve the vibration reduction effect for vibrations in the high frequency range.

[0013] In addition, in the vibration reduction mechanism of the present invention, the pile body and the rotational inertia mass damper may be arranged in series in a direction perpendicular to the propagation path, the second mounting member may be provided on top of each of the rotational inertia mass dampers, and the first mounting member and the second mounting member may be arranged in a crisscross pattern in a plan view.

[0014] With the above configuration, the vibration reduction mechanism is configured to have multiple vibration reduction mechanisms arranged in a band, and the vibration reduction mechanisms can be tuned to multiple different vibration frequencies by adjusting the axial stiffness or inertial mass of adjacent pile bodies. Therefore, it is possible to achieve the desired vibration reduction effect even in large-scale vibration-generating locations such as construction sites where there are many construction machines and construction vehicles that generate vibration, and where multiple tasks are performed over a wide area. In addition, by configuring the vibration reduction mechanism to have multiple rotary inertia mass dampers and pile bodies on one frame, it is no longer necessary to provide large weights and springs for each tuned vibration frequency as in conventional TMD dynamic vibration absorbers. This makes it possible to have a lightweight, compact configuration that does not require a large installation space. It also makes it possible to implement vibration reduction measures that are compatible with multiple vibration frequencies without incurring large costs.

[0015] Furthermore, in the vibration reduction mechanism of the present invention, the first mounting member and the second mounting member may be formed of H-shaped steel, a lower flange of the first mounting member may be in contact with the ground surface, a lower flange of the second mounting member may be connected to an upper flange of the first mounting member and the rotational inertia mass damper, respectively, and the first mounting member and the second mounting member may be arranged such that the directions of formation of their respective H-shapes are perpendicular in a plan view.

[0016] With the above configuration, the cross-sectional efficiency of the first and second mounting members with respect to bending rigidity and bending strength can be improved, which prevents damage to the vibration reduction mechanism caused by the load of the weight of the weight of the second mounting member disposed on the upper part of the mounting frame, and enables the desired vibration reduction effect to be achieved.

[0017] Furthermore, in the vibration reduction mechanism of the present invention, a ground surface reinforcement layer made of concrete or mortar or the like may be formed around the pile body, and the first mounting member may be provided on top of the ground surface reinforcement layer.

[0018] By using the above configuration, it is possible to suppress subsidence of the ground on which the vibration reduction mechanism is installed due to the upper load of the weight of the vibration reduction mechanism or the weight of the vibration reduction mechanism, and it is possible to prevent a decrease in the vibration reduction effect due to, for example, deviations in the installation positions of each part of the vibration reduction mechanism.

[0019] In addition, the vibration reduction method of the present invention is characterized in that any of the vibration reduction mechanisms described above is provided between a vibration generation point and a vibration disorder prevention point on the propagation path of the vibration wave generated from the vibration generation point.

[0020] By adopting the above-mentioned configuration, it is possible to provide a vibration reduction method that can obtain a desired vibration reduction effect without requiring a huge mechanism or requiring a large amount of cost. Effect of the Invention

[0021] According to the present invention, it is possible to provide a vibration reduction mechanism and a vibration reduction method that can reduce vibrations generated in conjunction with construction work without requiring a huge mechanism or a huge cost. [Brief description of the drawings]

[0022] [Figure 1] 5A and 5B are explanatory diagrams showing an installation position of an example of a vibration reduction mechanism according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a perspective view of an example of a vibration reduction mechanism according to an embodiment of the present invention. [Diagram 3] FIG. 2 is a cross-sectional front view of a rotary inertia mass damper in an example of a vibration reduction mechanism in accordance with an embodiment of the present invention. [Figure 4] 1 is an explanatory diagram of a vibration reduction model using an example of a vibration reduction mechanism according to an embodiment of the present invention. FIG. [Diagram 5]13 is a graph showing the results of a study (relationship between excitation frequency and response magnification) of a first comparative case using a vibration reduction model that uses an example of the vibration reduction mechanism according to an embodiment of the present invention. [Figure 6] 13 is a graph showing the results of a study (relationship between excitation frequency and response magnification) of a second comparative case using a vibration reduction model that uses an example of the vibration reduction mechanism according to an embodiment of the present invention. [Figure 7] 13 is a graph showing the results of a study (relationship between excitation frequency and response magnification) of a third comparative case using a vibration reduction model that uses an example of the vibration reduction mechanism according to an embodiment of the present invention. [Figure 8] 13 is a graph showing the results of a study (relationship between excitation frequency and response magnification) of a fourth comparative case using a vibration reduction model that uses an example of the vibration reduction mechanism according to an embodiment of the present invention. [Figure 9] 13 is a graph showing the results of a study (relationship between excitation frequency and response magnification) of a fifth comparative case using a vibration reduction model that uses an example of the vibration reduction mechanism according to an embodiment of the present invention. [Figure 10] 13 is a graph showing the results of a study (relationship between excitation frequency and response magnification) of a sixth comparative case using a vibration reduction model that uses an example of the vibration reduction mechanism according to an embodiment of the present invention. [Figure 11] 11 is a graph showing the results of examination of each comparison case (relationship between excitation frequency and vibration reduction level) using a vibration reduction model that uses an example of the vibration reduction mechanism according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] Hereinafter, a vibration reduction mechanism and a vibration reduction method according to an embodiment of the present invention will be described with reference to FIGS.

[0024] 1, the vibration reduction mechanism 1 according to this embodiment is provided in the propagation direction of vibration waves 21 generated by excitation at a vibration generation location 2, which is a construction site where construction machinery, construction vehicles, etc. are traveling and where construction work is being carried out. The vibration reduction mechanism 1 is also provided between the vibration generation location 2 and a vibration disorder prevention location 11 (hereinafter referred to as "residence 11") located near the vibration generation location 2.

[0025] As shown in FIG. 2, the vibration reduction mechanism 1 is composed of a pile body 3, a frame 6 composed of a first frame member 4 and a second frame member 5, a rotary inertia mass damper 7, a weight 8, and a ground surface reinforcing layer 9. In addition, unless otherwise specified in the following description, in this embodiment, the arrangement direction of the multiple pile bodies 3 and the rotational inertia mass dampers 7 in Figures 1 to 3 is referred to as the "X direction", the direction horizontally perpendicular to the X direction is referred to as the "Y direction", and the vertical direction perpendicular to the X direction and Y direction is referred to as the "Z direction".

[0026] The pile body 3 has an embedded portion 31 that penetrates the surface ground 91 and is embedded in the supporting ground 92, and a pile head portion 32 that is located on the ground surface above the ground G. Therefore, the pile body 3 has a length that reaches from the ground surface to the supporting ground 92 at the location where the vibration reduction mechanism 1 is provided. The pile body 3 is a steel pipe pile or an SC pile (a precast concrete pile wrapped in steel pipes). The embedment portion 31 has a structure for reducing peripheral friction at its outer periphery. For example, the structure may be such that asphalt is applied to the outer periphery of the embedment portion 31, or a double steel pipe may be provided on the outer periphery of the embedment portion 31.

[0027] The first frame member 4 and the second frame member 5 are each formed of an H-shaped steel. The standard of the H-shaped steel is not limited as long as the desired vibration reduction mechanism 1 can be formed. The first frame member 4 has a lower flange 41 that contacts the ground surface and a web 42 that is disposed within the XZ plane. The first frame members 4, 4 are provided on both sides of the pile body 3 in the X direction at equal intervals.

[0028] The second mounting member 5 is provided above the first mounting member 4 in the Z direction, with the lower flange 51 in contact with the upper flange 43 of the first mounting members 4, 4 and the web 52 disposed within the YZ plane. Therefore, the second mounting member 5 is disposed between the first mounting members 4, 4 in the Y direction.

[0029] With the above configuration, the first mounting member 4 and the second mounting member 5 are disposed so as to be perpendicular to each other in a plan view. The frame 6 is formed by connecting the upper flange 43 and the lower flange 51 of the first frame member 4 and the second frame member 5, which are stacked and arranged in the Z direction in the above-mentioned orientation, with fixing metal fittings such as bolts.

[0030] The rotational inertia mass damper 7 is positioned between the pile head 32 and the lower flange 51, with its upper end connected to the Z-direction underside of the lower flange 51 by a fixing bracket such as a bolt, and its lower end connected to the upper end of the pile head 32 by a fixing bracket such as a bolt.

[0031] As shown in Fig. 3, the rotational inertia mass damper 7 comprises a ball screw 71, a ball nut 72, and a rotary weight 73, which are circular in plan view (in the direction of the rotation axis). The rotational inertia mass damper 7 converts linear displacement (vertical relative displacement between both ends of the damper) into rotation by the ball screw 71, and the ball nut 72 rotates the rotary weight 73 while keeping the rotation axis constant. In the rotational inertia mass damper 7, the inertial mass is ψ, the diameter of the rotary weight 73 is D, the mass is m, the density is ρ, and the thickness in the Z direction is t, and the lead (thread spacing) of the ball screw 71 is L. d , the relative displacement is x, the weight rotation angle is θ, and the rotational moment of inertia is I θ Then, the load force P of the device against the relative acceleration (indicated by ... above x in the following equation) obtained by differentiating the relative displacement x twice with respect to time is given by the following equation. Also, the inertial mass ψ is given by the following equation.

[0032]

number

[0033]

number

[0034] In the above formula, the diameter D of the rotor 73 is equal to the lead L of the ball screw 71. d is sufficiently large relative to the mass m of the rotating weight 73, and the inertial mass ψ is proportional to the fourth power of the diameter D of the rotating weight 73. From the above, the inertial mass ψ can provide an inertial mass several hundred to several thousand times larger than the mass m of the rotating weight 73, and by being connected in series with the vertical spring of the pile, it functions as a TMD dynamic vibration absorber that is small but has a large mass.

[0035] The pile body 3, the second frame member 5, and the rotary inertia mass damper 7 are provided in parallel in the X direction between the first frame members 4, 4 with the same configuration and arrangement. In this embodiment, a plurality of pile bodies 3 are driven in the X direction at a predetermined interval X1, a plurality of second frame members 5 are installed in the Y direction between the first frame members 4, 4, and a rotational inertia mass damper 7 is disposed between each pile body 3 and the second frame member 5, and this configuration is provided continuously in the X direction. With the above configuration, the vibration reduction mechanism 1 is provided with a band-shaped vibration isolation belt 12 in the X direction. In addition, since the first frame member 4 and the second frame member 5 are perpendicular to each other in a plan view, the frame 6 is formed in a grid shape in a plan view that is continuous in the X direction.

[0036] The weight 8 is composed of a plurality of sandbags 81. The sandbags 81 are loaded on the upper flange 53 of the second frame member 5. The weight 8 is not limited to being composed of the sandbags 81 as long as the desired vibration reduction mechanism 1 is formed, and may be composed of, for example, steel plates stacked on the upper flange 53, or a concrete lump placed on top of the weight 8.

[0037] The ground surface reinforcing layer 9 is formed with a thickness of about several centimeters between the first frame member 4 and the ground G. Therefore, the vibration reduction mechanism 1 is provided on the ground surface reinforcing layer 9. The material of the ground surface reinforcing layer 9 is a known cement-based material such as sacrificial concrete or leveling mortar that has a compressive strength that will not be destroyed by the vibration reduction mechanism 1's own weight.

[0038] The first mounting member 4 is fixed onto the ground surface reinforcing layer 9 by driving a drive-in type fixing metal fitting, such as an anchor bolt, into the ground surface reinforcing layer 9 from above the lower flange 41. The fixing metal fitting may be driven through the ground surface reinforcing layer 9 and into the ground G. In the case of a configuration in which the ground surface reinforcing layer 9 is not formed between the first mounting member 4 and the ground G, the first mounting member 4 may be fixed to the ground surface by driving the fixing metal fitting from above the lower flange 41 into the ground G.

[0039] Next, the operation and effect of the vibration reduction mechanism and vibration reduction method according to the above-described embodiment will be described with reference to FIGS.

[0040] 1 to 3, the vibration reduction mechanism 1 includes a pile body 3, a frame 6 composed of a first frame member 4 and a second frame member 5, a rotational inertia mass damper 7, a weight 8, and a ground surface reinforcement layer 9. The pile body 3, the second frame member 5, and the rotational inertia mass damper 7 are provided in a plurality of units with the same configuration and arrangement between the first frame members 4, 4 at a predetermined interval X1 in the X direction, and the vibration reduction mechanism 1 includes a band-shaped vibration isolating belt 12 in the X direction. The vibration reduction mechanism 1 having the above configuration is provided between a vibration generation location 2 and a residence 11 located in the propagation direction of vibration waves 21.

[0041] Regarding the vibration reduction mechanism 1 according to the above embodiment, a vibration reduction model 13 is assumed in which the ground G shown in FIG. 4 is decomposed into a plurality of mass points to simplify the model, and the vibration reduction effect against vibration waves 21 is examined.

[0042] In FIG. 4, one mass point is assumed to be a lump of soil G of 10m x 10m x 10m. Four mass points are assumed, G1 to G4, and mass points G1 to G4 are located on the same horizontal extension line. Mass point G1 is the position of vibration generation point 2, and is excited by the action of external forces such as construction work and the passage of construction vehicles, and vibration waves 21 generated by the excitation propagate on vibration reduction model 13. Mass point G2 is located where vibration reduction mechanism 1 is provided, and is located a horizontal distance L away from mass point G1. Mass point G3 is located a horizontal distance L away from mass point G2. Mass point G4 is located a horizontal distance L away from mass point G3. Mass points G3 and G4 are locations for evaluating the vibration reduction effect of vibration reduction mechanism 1. Mass G of lump of soil G m The weight is 2,000 tons and the separation L is 10 m.

[0043] Each mass point is assumed to have a ground axial spring 93 with a spring constant k1 = 1000 kN / mm in the vertical direction. In addition, a shear spring 94 with a spring constant k2 = 400 kN / mm is assumed to exist between adjacent mass points in the horizontal direction. The ground axial spring 93 indicates the axial stiffness at the position where each mass point is assumed, and the shear spring 94 indicates the shear stiffness of the ground G.

[0044] The mass point G2 is provided with a vibration reduction mechanism model 14 arranged in parallel to a ground axial spring 93 provided at the mass point G2. The vibration reduction mechanism model 14 includes a weight mass point 82, a rotational inertia mass damper model 74 with an inertial mass ψ (ton) and a damping constant c (kN / kine), a base axial spring 61 having an axial stiffness k3, and a pile body axial spring 33 having an axial stiffness k4. The rotational inertia mass damper model 74 and the weight mass point 82 are arranged in parallel with the base axial spring 61. The axial stiffness (spring constant) of the pile body axial spring 33 is determined by dividing a load applied to the pile head of the pile body axial spring 33 by the amount of settlement caused by the load.

[0045] In the study of the vibration reduction mechanism using the inertial mass of this embodiment, the mass of the weight mass point 82 and the frame stiffness of the frame shaft spring 61 are ignored. m, and the spring constant k3 is set to ∞. Therefore, the vibration reduction model 13 forms a TMD dynamic vibration absorber mechanism in which the weight point 82, the rotary inertia mass damper model 74, and the pile shaft spring 33 are arranged in series in the vertical direction. The pile shaft spring 33 extends to a fixed end 95 assumed to be in the supporting ground 92, and the evaluation also takes into account ground displacement due to vibration waves 21. Note that when considering a case in which multiple vibration reduction mechanisms are combined, the case in which sandbag weights are placed on the ground surface, as in the conventional technology, is also evaluated.

[0046] In the vibration reduction model 13, the vibration reduction effect of the vibration reduction mechanism model 14 is examined for Examples 1 to 4 in which the inertial mass ψ (ton) at the mass point G2, the damping constant c (kN / kine), and the axial stiffness k4 (kN / mm) are as shown in the following table.

[0047] [Table 1]

[0048] In the study using the vibration reduction model 13, the responses of mass points G2, G3, and G4 when mass point G1 is subjected to acceleration vibration in the linear direction are evaluated in a frequency range up to 15 Hz, which is assumed to be a frequency range that may cause vibration disorders at the vibration generation point 2. i The ratio of the acceleration amplitudes (i=2~4) is the response magnification M of the transfer function at mass point i. i The calculation is performed using the following formula where (i=2 to 4), and the vibration wave 21 that passes through the vibration reduction mechanism model 14 provided at the mass point G2 and is transmitted to the mass points G3 and G4 is examined.

[0049]

number

[0050] In addition, in the study using the vibration reduction model 13, in six different cases where the configuration of the vibration reduction mechanism model 14 at the mass point G2 is different, the excitation frequency f due to the vibration wave 21 and the response magnification M iThe relationship between (i=2 to 4) is shown in Figs. 5 to 10, and the vibration reduction effect of each case configuration will be examined.

[0051] [Table 2]

[0052] As shown in FIG. 5, in case 1 without a vibration reduction mechanism, the response magnification (amplitude) M i As a result, there is a high possibility of vibration disorders occurring in the low frequency range.

[0053] As shown in FIG. 6, in Case 2, the vibration reduction mechanism model 14 having the configuration of the first embodiment is provided, and the response magnification M i In Case 2, the resonance characteristics near 4 Hz, which is the predominant frequency of the ground G in Case 1, are improved compared to Case 1. Therefore, by providing the vibration reduction mechanism model 14 in Case 2, it is possible to reduce vibrations in the low frequency range caused by vibration waves 21.

[0054] As shown in FIG. 7, in Case 3, the vibration reduction mechanism model 14 having the configurations of Examples 1 and 2 is provided, and the response magnification M i Therefore, by using a configuration in which multiple pile bodies 3 and rotary inertia mass dampers 7 are provided, as in the vibration reduction mechanism model 14 in Case 2, it is possible to achieve a vibration reduction effect for a wide range of vibration frequencies.

[0055] In case 4, the vibration reduction mechanism model 14 is not provided, and the mass G of the soil mass G is set at the mass point G2 as in the conventional technology. m Add a weight (sandbag) of 1000 tons, which is half the mass of the weight. As shown in Figure 8, the response magnification M iIn this case, the resonance characteristics in the vicinity of 3.5 Hz and 5 Hz are not improved, but vibrations of 5.5 Hz or more are almost not transmitted. From the above, it can be said that a vibration reduction mechanism using only a weight without vibration reduction mechanism 1 also has a certain vibration reduction effect in the high frequency range.

[0056] In case 5, the vibration reduction mechanism model 14 of the first embodiment and the mass G of the soil mass G applied to case 4 are m A weight (sandbag) of 1000 ton, which is half the mass of the weight, is attached to mass point G2. As shown in FIG. 9, the response magnification M i In this case, vibrations of 5.5 Hz or more are hardly transmitted. From the above, it is possible to achieve a vibration reduction effect for a wide range of vibration frequencies even with a configuration that combines the vibration reduction mechanism model 14 with a weight of a simple configuration.

[0057] In Case 6, the vibration reduction mechanism model 14 of Example 2-4 is provided in a band shape facing the vibration wave 21. As shown in FIG. 10, the above configuration increases the response magnification M i In this case, vibrations of 5 Hz or more are almost not transmitted. Also, the behavior of the response magnification is the smallest among the six cases examined. Therefore, by increasing the number of vibration reduction mechanism models 14 installed and forming them in a band shape in the propagation direction, it is possible to achieve a greater vibration reduction effect for vibrations in a wide range of frequencies.

[0058] The vibration reduction effects of cases 2 to 6 are compared in terms of vibration reduction level (response magnification to case 1 without vibration reduction mechanism). Vibration reduction level η in case j (j = 2 to 6) to case 1 j (j=2~6) is calculated using the following formula: η j If >0, the vibration at the mass point increases more than in Case 1, and η j If η is less than 0, it indicates that the vibration at that mass point is reduced compared to Case 1. From Figs. 5 to 10, the behavior of the response magnification with respect to the change in the excitation frequency of mass points G2, G3, and G4 in this embodiment is almost the same. jAs a representative value of η for each case of mass point G3 and each excitation frequency j Compare.

[0059]

number

[0060] As shown in Fig. 11, in Cases 2 and 3, the vibration reduction effect at the predominant frequency of ground G of 4 Hz is approximately -31 dB (reduced to approximately 1 / 30 of Case 1), so the vibration reduction effect is large in the low frequency range, but there is almost no vibration reduction effect in the high frequency range.

[0061] In addition, case 4 has a vibration reduction effect of approximately -3 dB in the high frequency range, but the vibration reduction effect in the low frequency range is smaller than that in cases 2 and 3, and vibration increases due to resonance with vibration wave 21 in the vicinity of the dominant frequency of ground G, which has shifted to the low frequency side.

[0062] In addition, in case 5, by installing the vibration reduction mechanism model 14 of embodiment 1, the resonance characteristics in the low frequency range seen in case 4 are greatly improved, and a vibration reduction effect equivalent to cases 1 and 2 can be obtained even in the low frequency range. Moreover, a higher vibration reduction effect than cases 1 and 2 can be obtained in the entire frequency range of 3.5 Hz or more.

[0063] Furthermore, even though Case 6 does not have a configuration for loading a weight like Cases 4 and 5, by providing the vibration reduction mechanism model 14 of Example 2-4, the inertial mass ψ can be increased, and the increased inertial mass ψ can act in the same way as a weight, thereby making it possible to achieve a vibration reduction effect equal to or greater than that of Case 5 across the entire frequency range.

[0064] From the above, it is possible to achieve a tuning effect in the low frequency range while reducing vibration in the high frequency range by using a vibration reduction mechanism formed from the inertial mass of the rotary inertia mass damper 7 and the axial rigidity of the pile body 3 in combination with a configuration in which the weight 8 is loaded, as in Case 5. In other words, by adjusting the axial rigidity of the pile body 3 and the inertial mass of the rotary inertia mass damper 7, the natural frequency of the rotary inertia mass damper 7 can be matched (tuned) to the excitation frequency or the predominant frequency of the ground G, which is in the low frequency range. The natural frequency f k is calculated by the following equation, where k is the axial stiffness of the pile body 3 and ψ is the inertial mass of the rotational inertia mass damper 7. With this mechanism, the vibration reduction mechanism 1 functions as a TMD dynamic vibration absorber, and can significantly reduce vibrations near the tuned frequency.

[0065]

number

[0066] Furthermore, by increasing the axial stiffness of the pile body 3 by using multiple band-shaped TMD mechanisms as in Case 6, a vibration reduction effect similar to that achieved when the inertial mass of the rotational inertial mass damper 7 is added to the mass of the weight 8 is achieved. The inertial mass is several hundred to several thousand times the mass of the rotating weight 73 in the rotational inertial mass damper 7. Therefore, by installing a lightweight rotational inertial mass damper 7, a vibration reduction effect equivalent to that achieved by adding the mass of a huge weight 8 can be achieved. With the above configuration, a desired vibration reduction effect can be achieved over a wide range of vibration frequencies.

[0067] In addition, by configuring the vibration reduction mechanism 1 as a belt-shaped vibration isolation belt 12 as in case 6, the axial stiffness of the multiple pile bodies 3 provided in a belt shape on one base 6 and the inertial mass of the multiple rotational inertial mass dampers 7 can be adjusted to tune the rotational inertial mass dampers 7 to multiple different vibration frequencies. Therefore, one base 6 and weight 8 can be shared by multiple rotational inertial mass dampers 7. With the above mechanism, it is not necessary to provide a vibration reduction mechanism using weights and springs for each tuned vibration frequency as in the conventional TMD dynamic vibration absorber, and the weight of the vibration reduction mechanism 1 can be replaced by the small mass of the inertial mass damper, and the spring uses the axial stiffness of the pile, making it a lightweight and compact mechanism. In addition, the vibration reduction mechanism 1 can be configured to achieve the desired vibration reduction effect without requiring a huge mechanism or a large installation space.

[0068] The first frame member 4 and the second frame member 5 are made of H-shaped steel, which improves the cross-sectional efficiency with respect to bending rigidity and bending strength. Therefore, the vibration reduction mechanism 1 can prevent damage caused by the upper load of the weight 8 or the weight of the second frame member 5 arranged on the upper part of the frame 6.

[0069] The ground surface reinforcing layer 9 is provided between the frame 6 (first frame member 4) and the ground G, and can suppress subsidence of the ground G on which the vibration reduction mechanism 1 is installed due to the load applied by the weight of the vibration reduction mechanism 1 and the weight of the vibration reduction mechanism 1. This makes it possible to prevent a decrease in the vibration reduction effect due to the occurrence of deviations in the installation positions of each part of the vibration reduction mechanism 1, etc.

[0070] Although the embodiments of the vibration reduction mechanism and vibration reduction method according to the present invention have been described above, the present invention is not limited to the above-mentioned embodiments and can be modified as appropriate without departing from the spirit of the present invention. 1 and 2, the vibration reduction mechanism 1 has the vibration isolation band 12 in the X direction, but the vibration wave 21 is a wave that propagates in all directions. Therefore, for example, when the vibration disorder prevention location is located around the vibration generation location 2, the vibration reduction mechanism 1 may have the vibration isolation band 12 formed to surround the vibration generation location 2.

[0071] In addition, in the above embodiment, the pile body 3, the rotational inertia mass damper 7, the base 6, and the weight 8 are arranged in series in the Z direction, but a viscous damping device such as an oil damper may be added in parallel to the rotational inertia mass damper 7 in the Z direction to add a damping coefficient, or the vibration reduction mechanism 1 may be configured with the rotational inertia mass damper 7 as an inertial top that can simultaneously impart inertial mass and viscous damping. Furthermore, if the axial stiffness of the pile is excessively large, an additional spring k' may be added in series to the inertia mass damper, and the series spring stiffness of the axial stiffness of the pile and the additional spring may be k. [Explanation of symbols]

[0072] 1. Vibration reduction mechanism 2. Vibration source location 3 Pile body 4 First frame member 5 Second mounting member 6 Mounting stand 7 Rotational Inertial Mass Damper 8 weight 9 Ground surface reinforcement layer 11. Vibration prevention points 31 Root section 32 Pile head 41 Lower flange 53 Upper flange 51 Lower flange 92 Supporting ground

Claims

1. It is provided between a vibration generating point and a vibration disorder prevention point on a propagation path of a vibration wave generated from the vibration generating point, A pile body including an embedded portion that is embedded into the supporting ground and reduces the peripheral friction force of the peripheral portion, and a pile head portion located on the ground surface; A stand including a first stand member made of steel and arranged adjacent to both sides of the pile body when viewed from the front on the ground surface, and a second stand member made of steel and arranged on an upper portion of the first stand member; A rotary inertia mass damper is disposed between the pile body and the second frame member between the first frame members, the upper end of the rotary inertia mass damper being connected to the second frame member and the lower end of the rotary inertia mass damper being connected to the pile head portion; Equipped with Vibration reduction mechanism.

2. A weight is provided on an upper portion of the second frame member and applies an upper load to the rotary inertia mass damper. The vibration reduction mechanism according to claim 1 .

3. The pile body and the rotary inertia mass damper are provided in series in a direction perpendicular to the propagation path, the second mounting member is provided on top of each of the rotary inertia mass dampers, The first mounting member and the second mounting member are arranged in a grid shape in a plan view. The vibration reduction mechanism according to claim 1 or 2.

4. The first frame member and the second frame member are formed of H-shaped steel, The lower flange of the first mounting member contacts the ground surface, a lower flange of the second frame member is connected to an upper flange of the first frame member and to the rotary inertia mass damper, The first mounting member and the second mounting member are arranged so that the directions of the H-shapes of the first mounting member and the second mounting member are perpendicular to each other in a plan view. The vibration reduction mechanism according to claim 1 .

5. A ground surface reinforcing layer is formed around the pile body, The first mounting member is provided on the upper part of the ground surface reinforcing layer. The vibration reduction mechanism according to claim 1 .

6. A vibration reduction method, characterized in that a vibration reduction mechanism according to any one of claims 1 to 5 is provided between a vibration generation location and a vibration disorder prevention location on the propagation path of a vibration wave generated from the vibration generation location.

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