JP3403314B2 - Centrifugal load test equipment - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a centrifugal load test device for applying a stress to a scale model of the ground or the like and testing its behavior.

[0002]

2. Description of the Related Art In order to investigate the strength of the ground when an earthquake occurs, an experiment is conducted in which stress is applied to a scale model of the ground.
When such an experiment is performed in a normal gravity field, it is difficult to reproduce such a large stress because a large earth pressure is applied deep inside the soil. For this purpose, suspend the sample container containing the scale model such as the ground, which is the sample, at the tip of the rotating arm, and rotate the rotating arm at high speed to give centrifugal acceleration to the sample and accelerate the scale model. Add 1
A centrifugal load test device is used which gives N times the power acceleration to a scale model of / N, and an example thereof is described in Japanese Utility Model Laid-Open No. 61-46439.

FIG. 3 shows an example of a conventional centrifugal force loading device, in which the power of a DC motor 30 is transmitted to a main shaft 32 via a speed reducer 31 and rotates in a horizontal plane of a cylindrical test pit 33. Drive the arm 34. Swing mounts 35, 35 are pin-connected to the tip of the rotary arm 34, and the swing mounts 35, 35 are swung up as the rotary arm 34 rotates. A sample container 36 containing a 1 / N scale model such as a structure or ground is attached to each rocking platform 35, and the rotation of the rotating arm 34 applies a centrifugal force N times the gravitational acceleration to the sample container 36. I am trying to give.

[0004]

In the centrifugal load test apparatus, the generated centrifugal acceleration α <G> is given by the rotational speed n <rpm> and the rotational diameter r <m> as shown in (Equation 1). To be

[Formula 1] α = (2πn / 60) ² · r = K · n ² · r K = (2π / 60) ² Therefore, when the rotating arm 34 rotates and the swinging platform 35 swings up in the horizontal direction, As shown in FIG. 4, the centrifugal acceleration α applied to the sample 37 differs depending on its position in the depth direction (radial direction when it is swung up). Now, assuming that the radius of gyration of the left end and the right end of the test piece 37 swinging horizontally is rA and rB, respectively, and the width (depth at rest) of the test piece 37 is h = rB-rA, centrifugal force is applied. The maximum value of acceleration is applied to the right end of the test piece (r = rB) in FIG. 4, and the minimum value is added to the left end of the test piece (r = rA) in FIG. 4, so the difference between the maximum value and the minimum value of the centrifugal acceleration applied to the test piece 37. △ α is

[Formula 2] Δα = K · n ² · (rB−rA) = K · n ² · h. In a centrifugal load test device, it is desirable to make the difference Δα in centrifugal acceleration in the depth direction as small as possible.
Especially in recent years, the specimens to be mounted on the centrifugal load test equipment have been increasing in size, such as liquefaction experiments using large-scale soil tanks. The difference in the centrifugal acceleration in the direction appears more significantly.

Therefore, when the desired centrifugal acceleration α to be applied to the specimen is given from the experimental conditions, in order to realize this, the rotation speed n and the rotation diameter r are appropriately determined based on (Equation 1). . On the other hand, the difference Δα in the centrifugal acceleration is determined by the depth h of the specimen, so that the rotation speed n ²
Proportional to. Therefore, in order to reduce the difference Δα in centrifugal acceleration, it is desirable to reduce the rotational speed n and increase the rotational radius r as much as possible to achieve a desired centrifugal acceleration. However, the conventional centrifugal load testing device uses a DC motor as a power source and has a structure in which the rotary arms rotate about the main shaft, that is, the left and right rotary arms pull each other around the main shaft, so when the rotation diameter is increased, Since a large force is applied to the arm structure, there is a limit in strength, which causes a problem that the rotation diameter is restricted. For example, according to the actual product, the rotation diameter is about 7m.
That was the limit of the arm structure.

An object of the present invention is to provide a centrifugal force load test apparatus capable of reducing the difference in centrifugal acceleration even when a large centrifugal acceleration is applied to a large test piece.

[0007]

In order to achieve the above object, the present invention provides a cylindrical test pit, a secondary side conductor annularly provided on the inner wall surface of the test pit, and a casing thereof. Of a rotating vehicle that is driven by a linear motor formed by a primary coil and a secondary conductor that are mounted on a surface facing the inner wall surface, and that rotates and runs along the inner wall surface, and It is attached rotatably inside,
A centrifugal force loading test, comprising: a swinging platform for applying a centrifugal acceleration to a sample housed therein by being swung up in the radial direction of the rotation of the rotating vehicle during rotation. A device is disclosed.

Further, according to the present invention, a wheel is provided on a surface of the rotating vehicle facing the inner wall surface, and an annular rail for supporting the wheel is provided on the inner wall surface. A force loading test device is disclosed.

Further, the present invention discloses a centrifugal force loading test apparatus characterized in that the linear motor is a magnetic levitation type, and the rotating vehicle is configured to rotate while traveling in a non-contact manner with the inner wall surface.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below. FIG. 1 is a perspective view showing an entire structure of a linear motor type centrifugal force loading test apparatus according to the present invention, which is a wheel linear motor car type centrifugal force loading test apparatus. This centrifugal force loading test device is used for the rotating vehicle 1, 1 that is the device body.
And a rotary joint 2 for supplying water, oil, etc., a slip ring 11 for transmitting and receiving electricity and signals, a support 3 for piping, wiring, etc. as main components. Slip ring
It travels along the inner wall surface of the cylindrical test pit 4 about 11 as an axis by the driving force of a linear motor as described later. Support 3
Is only a support for piping, wiring, etc., and is not a strong component that supports centrifugal force. A swing platform 5 is pin-connected to the rotating vehicle 1 as in the conventional device, and the swing platform 5 swings up as the rotating vehicle 1 travels. Sample container 6 with 1 / N scale model of structure, ground, etc.
By mounting the vehicle, running the rotating vehicle 1, and applying a centrifugal force N times the gravitational acceleration to the sample container 6, it is possible to reproduce a stress field equivalent to the actual ground.

Since each rotating vehicle 1 supports the centrifugal force during traveling by the inner wall surface of the cylindrical test pit 4, wheels 8 are provided on the surface facing the inner wall surface of the cylindrical test pit 4 of the rotating vehicle 1. 1 travels on a rail 7 laid on the wall surface of the cylindrical test pit 4 by the wheels 8. Further, in order to drive the linear motor, an iron core and a coil forming the primary side 9 of the linear motor are provided on the surface of the rotating vehicle 1 on which the wheels are provided, while the secondary side is on the track on which the rotating vehicle 1 travels. The conductor 10 is laid. Then, electricity is supplied to the coil on the primary side 9 via the support 3 via the slip ring 11 to generate a magnetic field, and the magnetic field is generated by the secondary side conductor.
The rotating vehicle 1 travels on the inner wall surface of the cylindrical test pit 4 by obtaining a driving / braking force by repelling / attractive with the magnetic field generated in 10. At this time, in order to make the gap between the primary side and the secondary side of the linear motor constant, the rail 7 and the secondary side conductor 10 are placed on the plate 20 laid on the inner wall surface of the cylindrical test pit 4 as shown in FIG. The secondary conductor 10 is installed and adjusted so that the height difference between the receiving surface of the wheel 8 and the secondary conductor 10 is constant.

In the centrifugal load test apparatus of FIG. 1 described above,
Since all of the centrifugal force applied to the rocking cradle containing the specimen is supported by the rails 7, the support 3 does not need special strength, and the strength of the arm structure is restricted even if the rotation diameter is increased. Disappears. For example, with this structure, an apparatus having a rotation diameter of 20 to 30 m can be easily configured.

FIG. 5 is a perspective view showing another constitutional example of the centrifugal load test apparatus according to the present invention, which is a centrifugal load test apparatus of a magnetic levitation linear motor set. The rough structure of this device is similar to that shown in FIG. 11, but the rotating vehicle 41 does not have wheels, and the magnetic levitation type linear motor mounted on the inner surface of the cylindrical test pit 4 makes no contact. To run. In the magnetic levitation type, since it is necessary to maintain a constant gap between the primary side and the secondary side of the linear motor, the support 42 has an adjustment mechanism 43 using an actuator,
43 is provided. FIG. 6 shows the structure of the adjusting mechanism 43, in which a slidably movable support 44 is fitted in the support 43 and is supported by an actuator 45. The actuator 45 detects the distance between the rotating vehicle 41 and the inner wall surface of the same cylinder pit 4 by a detector (not shown), and uses pressure oil supplied through the rotary joint 2 to generate a force according to the detected value. Controlled.

In the apparatus using the magnetic levitation linear motor car shown in FIG. 4, there is a limit in supporting the generated centrifugal force only by magnetism. Therefore, the support 42 is used as a strength component and the centrifugal force is generated by magnetic force. The structure should be supported by a support. However, by using magnetic levitation together, support can be realized even if the rotation diameter becomes large.

In the centrifugal load test apparatus described with reference to FIGS. 1 and 4, not only an experiment in which only a centrifugal force is applied, but a hydraulic vibrating table is mounted on the rocking pedestal 5 to provide a centrifugal force field. It is also possible to perform a vibration test on the specimen. Transmission and reception of electric and hydraulic pressure for controlling the centrifugal load test apparatus are all performed via the support 3 and via the central slip ring 11 or rotary joint 2. Further, in the centrifugal load test device, a liquefaction test of the sample is carried out. At that time, the measurement signal from the sensor attached to the sample is sent to the measuring room through the slip ring 11 via the support 3 as well as electricity.

[0016]

According to the present invention, since all or part of the generated centrifugal force is supported by the inner wall surface of the cylindrical test pit, a centrifugal load test with a large rotating diameter, that is, a large test piece is mounted. The device can be realized, and there is an effect that an experiment with a small difference in centrifugal acceleration in the depth direction can be performed even with a large-sized specimen. Further, since it is a linear motor drive, there is an effect that a gear device and a DC motor are not required, and space saving and noise reduction can be achieved.

[Brief description of drawings]

FIG. 1 is a perspective view showing the overall structure of a centrifugal load test apparatus according to the present invention.

FIG. 2 is a diagram showing a support structure by a pit inner wall surface of the vehicle of FIG.

FIG. 3 is a cross-sectional view showing the overall structure of a conventional centrifugal load test apparatus.

FIG. 4 is an explanatory diagram of a relationship between a rotation diameter and a centrifugal acceleration.

FIG. 5 is a perspective view showing another configuration example of the centrifugal load test apparatus according to the present invention.

6 is a diagram showing an adjusting mechanism that supports the vehicle of FIG.

[Explanation of symbols]

1,41 rotating vehicle 2 rotary joint 3,42 support 4 Cylindrical test pit 5 rocking stand 6 Specimen 7 running rails 8 wheels 9 Primary coil 10 Secondary conductor 11 slip rings

Continuation of the front page (56) Reference JP-A-5-18866 (JP, A) JP-A-58-53736 (JP, A) Actual development 5-65800 (JP, U) (58) Fields investigated (Int .Cl. ⁷ , DB name) G01M 19/00 G01D 21/00 G01L 5/00 G01M 7/00 G01N 3/00 JISST file (JOIS)

Claims (4)

(57) [Claims] 1. A cylindrical test pit, a secondary-side conductor annularly provided on an inner wall surface of the test pit, and a primary-side coil mounted on a surface of the casing facing the inner wall surface. A rotating vehicle that is driven by a linear motor formed by the secondary-side conductor to rotate along the inner wall surface, and is rotatably mounted inside the rotating vehicle and rotates when the rotating vehicle rotates. A centrifugal force loading test device, comprising: a swing base for applying a centrifugal acceleration to a sample housed therein by being swung up in the radial direction of the. 2. The wheel is provided on a surface facing the inner wall surface of the rotating vehicle, and an annular rail for supporting the wheel is provided on the inner wall surface. Centrifugal load test device. 3. The centrifugal load test apparatus according to claim 1, wherein the linear motor is a magnetic levitation type, and the rotating vehicle is configured to rotate while traveling without contacting the inner wall surface. 4. The centrifugal load test apparatus according to claim 3, further comprising a rotary joint and an arm mechanism attached thereto for supporting the rotating vehicle.