JP2908777B1 - Large depth circular shaft model experiment method and its apparatus - Google Patents

Abstract

Abstract: PROBLEM TO BE SOLVED: To provide a large-scale circular shaft model test method and apparatus capable of realizing an actual large-depth earth pressure distribution acting on a three-dimensional shaft in a centrifugal force field and deformation / destruction behavior of surrounding ground in a similar manner. I do. SOLUTION: A model ground (A) is placed in a test soil tank (100).
Is stored in the model ground (A).
Then, the test soil tank (100) is mounted on the centrifugal force loading device (10), and a predetermined centrifugal force field is given. And the model shaft (200)
Is changed by a driving device (300) provided outside the test soil tank (100), and an earth pressure gauge (S10, S10, S10...) Provided on the surface of the model shaft (200), and Earth pressure gauges (S11, S1) installed at appropriate places in the model ground (A)
(1, S11...) Measure the earth pressure distribution at a large depth and the deformation and fracture behavior of the surrounding ground.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a deep vertical circular shaft using a centrifugal force loading device (in the present application, a circular vertical shaft is used for convenience, but a vertical shaft having a rectangular section or the like is substantially the same, and a non-circular vertical shaft is used). The present invention relates to a method for actualizing a large-scale circular shaft model for experimentally confirming the load acting on the ground and the behavior of the surrounding ground, and an experimental apparatus therefor.

In recent years, excavation depths of up to 50
The construction of a large-scale and deep shaft exceeding 20 m exceeds 20 cases, and the necessity for the construction tends to increase more and more. In response to such demands, it is urgently necessary to review the conventional design and construction standards in order to design a deep soil retaining method and a rational and economical design of a shaft.

However, the actual earth pressure distribution acting on a shaft at a large depth, the deformation of the surrounding ground, the mechanism of destruction, and the like are not sufficiently clarified because there are few measured data. In the current design, when calculating the earth pressure at the time of temporary construction (during excavation in a shaft), the two-dimensional Rankin-Lessar earth pressure formula that increases linearly in the depth direction is used.
The empirical earth pressure equation of the lateral pressure coefficient is used, and the earth pressure calculation at the time of construction (at the time of completion) relies on the static earth pressure equation of the earth pressure distribution, which similarly increases linearly in the depth direction. However, it has been pointed out that such an application of the earth pressure calculation formula is questionable.

[0004] In view of the above, there have been proposed several methods for elucidating the earth pressure acting on a structure at a large depth using a conventional reduced model experiment apparatus, and the reduced model experiments are roughly classified into experiments in a gravitational field and a centrifugal force field.

[0005] Many of the conventional experiments for elucidating the earth pressure acting on a circular shaft at a large depth with a reduced model experimental device are performed in a gravitational field. Insert a model shaft that can be divided into multiple parts in the direction and can be reduced in diameter,
A ring-shaped rubber container is housed inside this model shaft,
Water is poured into and drained from the rubber container so that the diameter of the model shaft can be changed.Further, the inside of the rubber container is filled with water, and the earth pressure is measured by changing the water level inside the rubber container. And ask for it.

[0006] However, it is known that the above-mentioned experiment using the gravitational field has a problem in the method of preparing the model ground, and further has a problem in the similarity of the boundary condition with the model shaft, the stress level, and the like. Therefore, there is a problem that it cannot be treated as equivalent to the actual earth pressure distribution.

Therefore, recently, an experimental apparatus in a centrifugal force field has attracted attention. However, in this type of experimental apparatus, only the measurement of the earth pressure acting on a rigid two-dimensional vertical wall has been performed. The concept of the design load of the original shaft, such as a circular shaft, has been verified and has not reached the research level until it is reviewed.

[0008]

SUMMARY OF THE INVENTION Accordingly, the present invention is directed to a large-diameter circular cylinder capable of realizing an actual large-depth earth pressure distribution acting on a three-dimensional shaft in a centrifugal force field and deformation / fracture behavior of the surrounding ground in a similar manner. It is an object to provide a shaft model experiment device. Furthermore, a large-scale circular shaft model experiment device that buries a model of an underground structure such as a pile foundation structure or a tunnel around the shaft to enable the effect on nearby structures to be experimentally confirmed. It is an object to provide

[0009]

According to the present invention, a model ground A is housed in a test earth tank 100, and the model ground A is reduced to 1 / n of a plurality of vertically divided shapes in the model ground A. The circular shaft 200 is embedded, and the test soil tank 100 is mounted on the centrifugal force loading device 10 to give a predetermined centrifugal force field,
The diameter of the model shaft 200 is changed by a driving device 300 provided outside the test earth tank 100, and the earth pressure gauges S10, S10, S10... Provided on the surface of the model shaft 200 and the model ground A Earth pressure gauges S11, S11,
In S11, technical means for measuring the earth pressure distribution at a large depth and the deformation / destruction behavior of the surrounding ground were taken.

Next, a second aspect of the present invention is a test earth tank 1 containing a model ground A mounted on a centrifugal force loading device 10.
00 and one of a plurality of vertically divided shapes to be embedded in the model ground A.
/ N reduced model circular shaft 200, and a driving device 300 provided outside the test earth tank 100 and changing the diameter of the model shaft 200, and the earth pressure gauge S11, S11, S11...
Are provided with earth pressure gauges S10, S10, S10...

Therefore, the inventions of claims 1 and 2 provide a centrifugal acceleration field (referred to as a “centrifugal force field” in this application) that is n times the gravitational acceleration in the centrifugal force loading device 10. Accordingly, the reduced model circular shaft 200 has an effect of reproducing the same weight stress state as the real one.

Also, the method of the present invention provides a reduced model circular shaft 2
00 is defined as 1 / n of the vertically divided shape, and a drive device 300 for changing the diameter of the model shaft 200 is provided. Therefore, the structure of the model shaft 200 is reduced by reducing the model shaft 200 under centrifugal load. The present invention has an effect capable of confirming the load acting on the object, the active earth pressure which is referred to as the active state close to the earth pressure when the earth pressure breaks from the stationary state (the passive earth pressure), and the behavior of the surrounding ground.

Further, by expanding and contracting the diameter of the model shaft 200, the model shaft 200 can be vibrated, and the effect of confirming the influence during an earthquake can be exhibited.

Next, a third aspect of the present invention is a test soil tank 1 containing a model ground A mounted on a centrifugal force loading device 10.
00 and one of a plurality of vertically divided shapes to be embedded in the model ground A.
/ N, and a driving device 300 that is provided outside the test earth tank 100 and that changes the diameter of the model shaft 200, and the reduced model circular shaft 200
, Which are pressed against the inner peripheral surface of the reduced model circular shaft 200 to close the divided gaps SP1, SP1, SP1,. Earth pressure gauges S11, S11, S11 ...
And the earth pressure gauges S10 and S1 on the surface of the model shaft 200.
0, S10... Are provided.

Therefore, in addition to the above operation, the large-depth circular shaft model experimental apparatus according to the present invention presses the inside of the reduced model circular shaft 200 against the inner peripheral surface of the reduced model circular shaft 200 to form the divided gap. The leaf spring body 203 to be closed 203, 203, 203 ...
Is stored, so that the model ground is prevented from flowing into the reduced model circular shaft 200 from the divided gap of the reduced model circular shaft 200.

Next, according to the invention of claim 4, a test soil tank 1 containing a model ground A mounted on a centrifugal force loading device 10 is provided.
00 and a vertically split shape 1 embedded in the model ground A.
/ N reduced model circular shaft 200, and a driving device 300 provided outside the test earth tank 100 and changing the diameter of the model shaft 200. One of the model shaft 200 is a fixed shaft. The part 202 is fixed to the test tank 100,
The other side of the driving device 300
Is movable in the direction of coming and going with respect to the fixed-side shaft portion 202, and the reduced model circular shaft 200 is pressed into contact with the inner peripheral surface of the reduced model circular shaft 200 to divide the gap SP.
1, a leaf spring body 203 for closing SP1 is housed, and an earth pressure gauge S11, S11, S11 is placed at an appropriate place in the model ground A.
... are provided on the surface of the model shaft 200 with the earth pressure gauges S10, S
10, S10... Are provided by technical means.

Therefore, in addition to the above-described operation, the large-scale circular shaft model experiment apparatus of the present invention has a model shaft 200 fixed to the test earth tank 100 as one fixed shaft portion 202 and a movable shaft shaft as the other side. The model shaft 200 cannot be accurately reduced in diameter since the model shaft 200 can be moved in the direction of contact and separation with respect to the fixed shaft portion 202 by the driving device 300 as the portion 201. It has the effect of reducing the diameter. Since the earth pressure acting on this kind of circular shaft acts on the axis symmetrical, the actual main earth pressure can be confirmed with a simple configuration in which only the moving shaft section 201 moves.

Next, the invention of claim 5 relates to a test earth tank 1 containing a model ground A mounted on a centrifugal force loading device 10.
00 and a vertically split shape 1 embedded in the model ground A.
/ N, and a drive unit 300 provided outside the test shaft 100 and moving one side of the model shaft 200, and the test soil bath 100 is a container having an open top. And a drive source storage chamber 102 is provided below a bottom surface 101 of the model shaft 200.
Is fixed upright on the bottom surface 101 of the test soil tank 100 as one fixed side shaft portion 202, and the other side is the movable side shaft portion 201
The lower end is disposed so as to protrude below the through-hole 103 provided on the bottom surface 101 so as to be movable toward and away from the fixed shaft portion 202, and the earth pressure gauge S1 is placed at an appropriate position in the model ground A.
, S11, S11,...
At the intersection between the peripheral surface of the shaft and the diameter line facing the moving direction of the moving-side shaft part 201, the earth pressure gauges S10, S10, S10.
Is provided, and the driving device 300 includes a lower driving device portion 300a housed in the driving source housing chamber 102;
Upper drive unit 300b provided above model ground A
The lower drive unit 300a includes a motor 301 provided in the drive source storage chamber 102 and a motor 3
01 and a screw rod 302 rotating in the direction perpendicular to the longitudinal center axis of the model shaft 200, and the moving-side shaft 20
And a nut 303 which is fixed to the lower end projection and which reciprocates with the rotation of the screw rod 302.
0b is a second screw rod 3 arranged in parallel with the screw rod 302.
04, and a second nut 305 fixed to a portion of the movable shaft 201 protruding above the model ground A and reciprocating with the rotation of the second screw rod 304. The upper drive unit 300b includes the screw rod 30
2 and one end of the second screw rod 304 are connected to the test earth tank 100, respectively.
, And the two projecting portions are connected by a transmission such as a timing belt 306. Further, the reduced model circular shaft 200 is inserted into the reduced model circular shaft 200.
Leaf spring body 20 that presses against the inner peripheral surface of block 0 to close the divided gap
In this case, technical means for accommodating 3,203 are taken.

Therefore, in addition to the above operation, the large-depth circular shaft model experimental apparatus of the present invention can
0, there is no obstruction in the model ground A, so that the behavior of the actual ground which does not disturb the behavior of the surrounding ground can be confirmed. Furthermore, the pile foundation structure is provided around the shaft. By embedding a model of an underground structure such as an object or a tunnel, an effect of being able to experimentally confirm the influence on a nearby structure is exhibited.

Next, according to the invention of claim 6, the test soil tank 1 containing the model ground A to be mounted on the centrifugal force loading device 10 is provided.
00 and a vertically split shape 1 embedded in the model ground A.
/ N, and a drive unit 300 provided outside the test shaft 100 and moving one side of the model shaft 200, and the test soil bath 100 is a container having an open top. And a drive source storage chamber 102 is provided below a bottom surface 101 of the model shaft 200.
Is fixed upright on the bottom surface 101 of the test soil tank 100 as one fixed side shaft portion 202, and the other side is the movable side shaft portion 201
The lower end is disposed so as to protrude below the through hole provided in the bottom surface 101 so as to be movable toward and away from the fixed-side shaft portion 202, and the earth pressure gauges S 11, S 1 are provided at appropriate places in the model ground A.
, S11,... At the intersection of the peripheral surface of the movable shaft section 201 and the diameter line facing the moving direction of the movable shaft section 201, earth pressure gauges S10, S10, S10.
A distance meter S21, S22, S23... For measuring the distance to the upper surface of the model ground A is provided at an appropriate place above the model ground A.
02 and an upper drive unit 300b provided above the model ground A. The lower drive unit 300a is provided in the drive source storage chamber 1
02, a screw rod 302 rotated by the motor 301 and oriented in a direction perpendicular to the longitudinal center axis of the model shaft 200, and a screw rod 302 fixed to the lower end protruding portion of the movable shaft portion 201. And a pair of guide rails 30 that guide the nut 303 only in the direction of contact and separation with respect to the fixed shaft 202.
7, 307, and the upper drive unit 300b
Is a second screw rod 304 arranged in parallel with the screw rod 302.
And a second nut 305 which is fixed to a portion of the movable shaft portion 201 projecting above the model ground A and which advances and retreats by rotation of the second screw rod 304.
00a and the upper drive unit 300b, one end of each of the screw rod 302 and the second screw rod 304 is freely inserted and protruded outside the side surface of the test soil tank 100, and both protruding parts are connected to the timing belt 3
06, and a displacement position measuring instrument S3 is provided below the nut 303 and above the moving side shaft section 201.
1, S32, and the reduced model circular shaft 2
In 00, a technical means is provided in which leaf spring bodies 203, 203 for pressing the inner peripheral surface of the reduced model circular shaft 200 to close the divided gap portion are housed.

Therefore, the large-scale circular shaft model experiment apparatus of the present invention comprises a plurality of rangefinders S21, S22, S2 for measuring the distance to the upper surface of the model ground A above the model ground A at an appropriate position.
Since 3 is provided, the effect of being able to test the influence on the ground surface around the shaft due to the shaft deformation is exhibited.

Further, according to the present invention, the displacement position meters S31 and S31 are provided below the nut 303 and above the moving-side shaft portion 201.
Since 32 is provided, the function of confirming the movement amount of the moving-side shaft portion 201 is exhibited.

[0023]

Next, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the figure, reference numeral 10 denotes a conventionally known centrifugal force loading device. Although not shown in the figure, a driving device is accommodated in the main body 11 so that the vertical shaft 12 rotates at high speed. A horizontal shaft 13 is attached to the vertical shaft 12. At both ends of the horizontal shaft 13, mounting tables 15a, 15b are mounted by horizontal shafts 14a, 14b orthogonal to the horizontal shaft 13.
Is provided.

On the mounting tables 15a and 15b, the large-scale circular shaft model experimental apparatus 100A of the present invention is mounted on one side, and the balance weight 16 is mounted on the other. When the horizontal shaft 13 rotates at high speed, the mounting tables 15a and 15b As shown by a broken line in FIG. 1 ", the centrifugal force field (598 m / S ² (60 g in this embodiment as an example) in the present embodiment as an example, In the preliminary experiment, 785 m / S ² (80 g)) was loaded.

Although not shown, power supply and signal extraction wires are connected to the large-scale circular shaft model experimental apparatus 100A of the present invention, and these are provided with a slip ring (not shown) provided above the vertical shaft 12. And a control and signal value arrangement / display device C such as a power supply device and a computer.

In the method of the present invention, a centrifugal force loading device as described above is used. A test soil tank 100 is separately prepared, and the model ground A is stored in the test soil tank 100. The test tank 100 and the model ground A will be described later.

Then, a 1 / n reduced model circular shaft 200 having a vertically divided shape is embedded in the model ground A, and the test soil tank 100 is placed in a large depth circular shaft as shown in FIG. The model experimental apparatus 100a is mounted on the centrifugal force loading apparatus 10 to give a predetermined centrifugal force field, and the model shaft 200
Drive 300 provided outside test soil tank 100
And the earth pressure gauge S provided on the surface of the model shaft 200
, And soil pressure gauges S11, S11, S11... Provided at appropriate places in the model ground A measure the earth pressure distribution at a large depth and the deformation / destruction behavior of the surrounding ground.

Therefore, according to the method of the present invention, by applying the centrifugal force field which is n times the gravitational acceleration as described above, the reduced model circular shaft 200 can reproduce the same self-weight stress state as the actual model, and the reduced model circular shaft can be reproduced. Since the body 200 is formed as 1 / n of a vertically divided shape and has a driving device 300 for changing the diameter of the model shaft 200, by reducing the reduced model shaft 200 in a centrifugal load state, It can also confirm the load acting on the structure, the active earth pressure, which is said to be the active state close to the earth pressure when the earth pressure breaks from the static state (the passive earth pressure), and the behavior of the surrounding ground. By expanding and contracting the diameter of the model shaft 200, the influence at the time of an earthquake can be confirmed. The similarity between the actual case and the model case in the n-fold centrifugal force field is as shown in Table 1 below.

[0029]

[Table 1]

Next, a second aspect of the present invention is an apparatus for performing the above-described large-scale circular shaft model experiment method, wherein the test earth tank 1 containing the model ground A to be mounted on the centrifugal force loading device 10 is provided.
00 and one of a plurality of vertically divided shapes to be embedded in the model ground A.
/ N, and a driving device 300 provided outside the test earth tank 100 and changing the diameter of the model shaft 200.

The test tank 100 is a centrifugal force loading device 1
In this embodiment, duralumin (aluminum) is used because there is a restriction on the mass that can be mounted on the zero and it is necessary to reduce the weight.
To form a box with an open top. In addition,
The member of the test tank 100 may be a steel material if a larger centrifugal force loading device 10 is used, and it is a matter of course that titanium or various alloys having higher strength may be used. The test soil tank 100 may be made of acrylic so that a change in strain in the model ground A can be confirmed.

In the illustrated embodiment, the test soil tank 100 is provided with a drive source storage chamber 102 below a bottom surface 101. In the drive source storage chamber 102, a part of a driving device 300 described later is provided. It is designed to be stored. In addition,
Although not shown, it is a matter of course that the test tank 100 can be firmly fixed to one of the mounting tables 15a and 15b by screwing or the like.

The model ground A may be made of a soil close to the actual ground, such as sand, clay, alternate layers, etc., in addition to sand as the sample soil.

The 1 / n reduced model circular shaft 200 having a plurality of vertically divided shapes to be buried in the model ground A may be made of any appropriate material. In this embodiment, duralumin is used. And, although the surface was finished smoothly, it is considered that frictional force actually acts between the shaft surface and the ground, and the surface processing of the reduced model circular shaft 200 is roughened, Of course, it is desirable to reproduce the frictional force.

The reason why the reduced model circular shaft 200 is set to 1 / n is that the centrifugal force of 60 G is loaded in the present embodiment, so that it is 1/60. What is necessary is just to determine according to force.

The reason why the reduced model circular shaft 200 is divided into a plurality of vertically divided shapes is to measure the passive earth pressure and also reduce the diameter to measure the active earth pressure. As shown in FIG. 4 (divided into two in the figure), appropriate divided gaps SP1, SP1, SP1,... Are provided in the divided portions of the shape, and the divided gaps SP1, SP1, SP1,.
The diameter can be reduced by narrowing.

Needless to say, the reduced model circular shaft 200 can not only be reduced in diameter but also can be expanded. If the reduction and expansion are repeated at a predetermined interval, it may be affected by an earthquake or vibration during construction. The earth pressure applied to the reduced model circular shaft 200 and the movement of the surrounding ground can be confirmed. Although not shown in the drawings, the actual vertical shaft deformation can be faithfully reproduced by further dividing the vertically divided one into a plurality of horizontally.

The divided gaps SP1, SP1, SP1,.
.. When the sample soil flows into the reduced model circular shaft 200, the similarity with the actual earth pressure is lost. Therefore, according to the invention of claim 3, the reduced model circular shaft 200 includes: The leaf spring bodies 203, 203, 203,... Which press the inner peripheral surface of the reduced model circular shaft 200 to close the divided gaps SP1, SP1, SP1,.

The leaf springs 203, 203, 203,...
May be any as long as it presses against the inner peripheral surface of the reduced model circular shaft 200 to close the divided gaps SP1, SP1, SP1,..., But in the illustrated embodiment, it is most apparent in FIG. As shown, a part of both ends is formed in a substantially elliptical cross section which overlaps inside and outside, and a part of the curved surface is projected outward from between the divided gap portions SP1. Therefore, when narrowing or widening the divided gap portion SP1, the leaf spring body 203 must be deformed against the spring force, and the hermeticity is ensured by a predetermined pressing force, and will be described later. The reaction force of the earth pressure applied to the moving-side shaft section 201 is applied to the leaf spring body 203.
To move the moving-side shaft section 201 with high precision.

Further, the number of vertical divisions of the reduced model circular shaft 200 may be arbitrary, but this embodiment and "Claim 4"
In the invention of claim 6, it is divided into two. That is, one side of the model shaft 200 is fixed shaft 2
02 is fixed to the test soil tank 100, and the other side is the moving-side shaft section 201, and the fixed-side shaft section 2 is driven by the driving device 300.
02 (in FIG. 2 to FIG. 4, left and right directions, and when reducing the diameter, the movable shaft 201 can be moved in the direction shown in FIG. 2 to FIG. 4 to the right). It has been done.

As described above, the reduced model circular shaft 200 is divided into two parts. Since the earth pressure acting on the circular shaft acts on the axial shaft as described above, the movement of the movable side shaft portion 201 alone is referred to as the movement. This is because the actual active earth pressure can be confirmed with a simple configuration.

Further, the driving device 300 includes a link mechanism and a cam mechanism in addition to the motor 301 of this embodiment.
In this embodiment and “Claim 4” to “Claim 6”, the lower drive unit 300a housed in the drive source housing chamber 102 and the model ground A The upper drive unit 300b is provided above.

The lower drive unit 300a is provided with a motor 301 provided in the drive source accommodating chamber 102.
And a nut 303 fixed to the lower end protruding portion of the movable shaft portion 201 and screwed forward and backward by the rotation of the screw bar 302.

That is, the screw 301
By rotating 02, the nut 303 advances and retreats, and the movable shaft section 201 connected to the nut 303 moves in the left-right direction in FIGS. 2 to 4. Note that a speed reducer 308a and a torque limiter 308b are interposed between the motor 301 and the screw rod 302 to reduce the rotation speed (1/10 to 1/200) and reduce the torque by about 1
The nut 303 can be driven even in a high centrifugal force field of 0 to 200 times, and the feed accuracy is improved.

The upper drive unit 300b is fixed to a second screw rod 304 arranged in parallel with the screw rod 302 and a portion of the movable shaft 201 protruding above the model ground A, and And a second nut 305 that advances and retreats with the rotation of the two screw rods 304. In other words, the rotation of the second screw rod 304 causes the second nut 305 to advance and retreat, and the upper part of the movable shaft section 201 also moves.

The lower drive unit 300a and the upper drive unit 300b allow one end of each of the screw rod 302 and the second screw rod 304 to be freely inserted and protruded outside the side surface of the test soil tank 100, Both projecting portions are connected to the timing belt 306 by a transmission such as pulleys 306a, 306a.

That is, the screw rod 302 and the second screw rod 304 are rotated synchronously, and the nut 303
And the second nut 305 are moved in the same direction at the same distance and at the same speed, so that the moving-side shaft portion 201 moves only in the direction of contact and separation with respect to the fixed-side shaft portion 202 with the moving-side shaft portion 201 standing upright. The upper and lower ends of the movable shaft section 201 are provided with nuts 30.
3 and the second nut 305 so as to be hardly displaced by an external force other than the driving device 300.

In the illustrated embodiment, the fixed shaft 2
02 is provided with reaction force receivers 401, 402, and 403 so that the movable shaft portion 201 can be accurately moved and maintained with respect to the reaction force by the driving device 300 and the earth pressure from outside the shaft. The reaction force receivers 401, 402, 4
Needless to say, 03 should be provided as needed.
Strictly speaking, there is a difference with respect to the natural ground, but actually this reaction force receiver 401, 402, 40
3, the measurement accuracy was higher when the reaction force receivers 401, 402, and 403 were provided.

In order to further secure the uprightness of the movable shaft section 201, the nut 30 according to the invention of claim 6 is used.
3 is provided with a pair of guide rails 307, 307 for guiding the shaft 3 to the fixed side shaft portion 202 only in the direction of contact and separation. Although the guide rails 307 and 307 are not shown in the illustrated example, referring to FIG. 3, grooves are provided on both sides of the nut 303, and rails 30 whose tips fit into the grooves are provided on both sides.
7 and 307 are parallel to the nut 303 and the test soil tank 10
It is fixed at 0.

In the above description, it is assumed that the moving-side shaft section 201 secures the uprightness. However, it is obvious that the actual shaft is working so as to be constructed vertically, but only when the vertical shaft is necessarily vertical due to excavation errors and unbalanced load applied during excavation. Not necessarily. Therefore, the lower drive unit 300a and the upper drive unit 300b are driven by separate drive sources, or the pulleys 306a and 306
By making the diameter of a different, the moving-side vertical shaft portion 201 can be appropriately inclined so that the actual vertical shaft can be more faithfully simulated.

The earth pressure gauges S11, S11, S11... Are provided at appropriate places in the model ground A, and the earth pressure gauges S10, S10, S10.

In the illustrated example, the earth pressure gauges S11 and S10 use a gate-type one-way load cell, and may be buried in an appropriate place. An appropriate interval is provided in the vertical direction at a point of intersection with the diameter line in the moving direction of the moving-side shaft portion 201, and the moving-side shaft portion 201 is buried in the surface of the moving-side shaft portion 201 so that measurement can be performed from a shallow portion to a deep portion. The earth pressure gauge S1
0, S11 are gate type, diaphragm type, bending type, shear type,
It goes without saying that an appropriate one such as a compression type may be used.
The earth pressure gauge S11 in the example of FIG. 1 measures the earth pressure in a horizontal rectangle in the horizontal direction, the vertical rectangle in the vertical direction, and the circular shape in the tangential direction.

The earth pressure gauge S10 is mounted on the fixed shaft section 202.
In addition, a CCD camera or the like may be provided on a part of the surface of the movable shaft section 201 so that the behavior of the ground destruction can be visually checked.

The invention according to claim 6 further includes a range finder S 21, S 22, S 23.
, And displacement position measuring instruments S31 and S32 for measuring the displacement amount of the moving shaft section 201 are provided.

The rangefinders S21, S22, S23...
Is arranged above the model ground A and measures the distance from the upper surface of the model ground A. This rangefinder S2
For 1, S22, S23,..., A laser range finder or the like can be used. In addition, this rangefinder S21, S22, S23 ...
It is desirable to provide a plurality of juxtapositions in parallel so as to measure the influence of the model shaft 200 to a portion away from the outer peripheral edge by a predetermined distance, or to measure displacements at a plurality of locations at the same time. In addition, the rangefinders S21, S22,
If S23... Is disposed on a guide rail (not shown) provided in the moving direction of the moving shaft section 201 in a direction passing through the central axis of the model shaft 200, and it is movably arranged by sequencer control, an arbitrary position is obtained. It is more desirable to be able to measure or continuously measure a predetermined distance.

The displacement position measuring devices S31, S32
Is used for precision control of the displacement of the movable shaft section 201. In the embodiment, a fixed-side diffractive light interference type called a micro linear encoder is used below the nut 303 and above the movable shaft section 201. To the nut 30
Scales M, M shown in FIG. 2 are attached to the moving members of the shaft 3 and the moving shaft section 201.

Although not shown, in the present embodiment, the timing belt 306 is provided with a conventionally known tension adjusting device to improve the feeding accuracy. In addition, the movable side shaft portion 201 and the range finder are provided. S21, S22, S23 ...
In the and, a limit switch is provided to prevent a movement exceeding a predetermined value.

In the figure, 309 and 309 are screw rods 30.
3 shows a bearing of the second and second screw rods 304.

[0059]

Since the present invention is as described above, the actual deep earth pressure can be experimentally measured by using the 1 / n reduced model circular shaft 200 under the centrifugal load. It is possible to provide a circular shaft model experiment method and apparatus.

The present invention also relates to a reduced model circular shaft 20
0 can be expanded and reduced, so that not only the static earth pressure, the active earth pressure but also the passive earth pressure can be measured. Further, since the model ground A is provided with the earth pressure gauges S11, S11, S11. It is possible to provide a large-scale circular shaft model experiment device capable of measuring a change in earth pressure at the same time.

Further, according to the present invention, when the movable shaft section 201 is inclined, an actual excavation error of the shaft and an eccentric load at the time of construction can be reproduced. It is possible to provide a large-scale circular shaft model experiment device capable of confirming the influence of the above.

It should be noted that the second aspect of the present invention relates to a driving device 3
00 is provided outside the test tank 100 so that no extra drive mechanism is installed in the ground, so that the actual earth pressure distribution on the semi-dimensional ground can be measured. When a model of an underground structure such as a pile foundation structure or a tunnel is buried in the vicinity of the building, it is possible to provide a large-depth circular shaft model test apparatus capable of experimentally confirming the influence on adjacent structures.

In addition, the invention of claim 3 provides a method of contacting the inner peripheral surface of the reduced model circular shaft 200 with the divided gap SP1,
SP1, SP1,...
Because 201 ... is stored, in addition to the above effects,
It is possible to provide a large-depth circular shaft model experiment apparatus capable of performing more accurate measurement without the model ground A flowing into the reduced model circular shaft 200.

Further, the invention of claim 4 provides that the reduced model circular shaft 200 is divided into two vertical parts, and the earth pressure gauges S10 and S10 are provided at the intersection with the diameter line of the moving shaft 201 in the moving direction. , S10,..., Provide a large-depth circular shaft model experiment apparatus capable of accurately measuring the earth pressure acting on the axial object in addition to the above-described effects.

Further, the invention of claim 4 provides the driving device 3
Reference numeral 00 denotes a lower drive unit 300a housed in the drive source storage chamber 102 and an upper drive unit 300b provided above the model ground A.
00a is a motor 30 provided in the drive source storage chamber 102.
1 and a screw rod 302 rotated by the motor 301 and oriented in a direction orthogonal to the longitudinal center axis of the model shaft 200.
And a nut 303 fixed to the lower end protruding portion of the movable shaft portion 201 and reciprocated by the rotation of the screw rod 302. The upper drive device 300b is arranged in parallel with the screw rod 302. The lower drive unit includes a screw rod 304 and a second nut 305 fixed to a portion of the movable shaft 201 protruding above the model ground A and reciprocating with the rotation of the second screw rod 304. 300a and upper drive unit 30
0b means that one end of each of the screw rod 302 and the second screw rod 304 is loosely inserted and protruded to the outside of the side surface of the test soil tank 100, and both protruding portions are connected by a transmission such as a timing belt 306. Therefore, in addition to the above-described effects, extremely accurate movement of the moving-side shaft portion 201 can be performed, and a large-depth circular shaft model experiment device capable of firmly holding the moving-side shaft portion 201 at the moving position can be provided.

Further, the invention of claim 5 relates to the model ground A
A plurality of distance measuring devices S21, S22, S23... For measuring the distance from the upper surface of the model ground A are provided at appropriate places above the ground, so that the influence of the deformation of the shaft on the ground surface around the shaft is measured. It is possible to provide a large-scale circular shaft model experiment device capable of conducting experiments.

Further, according to the present invention, the displacement position measuring devices S31 and S31 are provided below the nut 303 and above the moving-side vertical shaft portion 201.
Since the 32 is provided, it is possible to provide a large-depth circular shaft model test apparatus capable of reliably controlling the moving-side shaft section 201.

[Brief description of the drawings]

FIG. 1 is a front view showing a position embodiment of the present invention.

FIG. 2 is a longitudinal sectional view of a main part of the large-scale circular shaft model test apparatus of the present invention.

FIG. 3 is a bottom view of a main part of the large-scale circular shaft model experiment apparatus of the present invention.

FIG. 4 is a plan view of a reduced model circular shaft used in the present invention.

[Explanation of symbols]

 A Model ground 10 Centrifugal force loading device 100 Test earth tank 101 Bottom surface 102 Drive source storage room 200 Reduced circular model shaft 201 Moving side shaft 202 Fixed side shaft 203 Leaf spring body 300 Drive 300a Lower drive 300b Upper drive Device part 301 Motor 302 Screw rod 303 Nut 304 Second screw rod 305 Second nut 306 Timing belt 307 Guide rail S10 Soil pressure gauge S11 Soil pressure gauge S21 Distance measuring instrument S22 Distance measuring instrument S23 Distance measuring instrument S31 Displacement measuring instrument S32 Displacement position Measuring instrument

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-2-176534 (JP, A) JP-A-4-13946 (JP, A) (58) Fields investigated (Int.Cl. ⁶ , DB name) G09B 25/00 G09B 9/00 G01M 7/02 G01M 19/00

Claims (6)

(57) [Claims] 1. A model ground (A) in a test soil tank (100).
Is stored in the model ground (A).
Then, the test model tank (100) is mounted on the centrifugal force loading device (10) to give a predetermined centrifugal force field. Is changed by a driving device (300) provided outside the test soil tank (100), and the earth pressure gauges (S10, S1) provided on the surface of the model shaft (200) are changed.
0, S10...) And the earth pressure gauge (S11, S11, S11...) Provided at an appropriate place in the model ground (A) to measure the earth pressure distribution at a large depth and the deformation and fracture behavior of the surrounding ground. Large depth circular shaft model test method. 2. A test soil tank (100) containing a model ground (A) mounted on a centrifugal force loading device (10), and a 1 / n of a plurality of vertically divided shapes embedded in the model ground (A). And a drive unit (300) provided outside the test soil tank (100) to change the diameter of the model shaft (200), and the model ground (A) Soil pressure gauge (S11, S1
, S11...) Are provided on the surface of a model shaft (200) with earth pressure gauges (S10, S10, S10...). 3. A test soil tank (100) containing a model ground (A) mounted on a centrifugal force loading device (10), and a 1 / n of a plurality of vertically divided shapes embedded in the model ground (A). And a drive unit (300) provided outside the test tank (100) for changing the diameter of the model shaft (200). A leaf spring body (2) that presses against the inner peripheral surface of the reduced model circular shaft body (200) to close the divided gaps (SP1, SP1, SP1,...) Inside (200).
03, 203, 203...), And the earth pressure gauges (S11, S1) are put in place in the model ground (A).
, S11...) Are provided on the surface of a model shaft (200) with earth pressure gauges (S10, S10, S10...). 4. A test soil tank (100) containing a model ground (A) to be mounted on a centrifugal force loading device (10), and 1 / n of a vertically split shape embedded in the model ground (A). A reduced model circular shaft (200) and a driving device (300) provided outside the test earthen tank (100) for changing the diameter of the model shaft (200); Is one of the fixed shafts (2
02) and fixed to the test earth tank (100), and the other side can be moved in the direction of moving toward and away from the fixed shaft (202) by the driving device (300) as the movable shaft (201). A leaf spring body (203, 203) in the reduced model circular shaft (200) that presses against the inner peripheral surface of the reduced model circular shaft (200) to close the divided gap (SP1, SP1).
And the earth pressure gauges (S11, S1) are put in place in the model ground (A).
, S11...) At the intersection of the peripheral surface of the moving shaft (201) and the diameter line facing the moving direction of the moving shaft (201). S1
0 ...), a large-scale circular shaft model experimental device. 5. A test soil tank (100) containing a model ground (A) to be mounted on a centrifugal force loading device (10), and 1 / n of a vertically split shape embedded in the model ground (A). The test earth tank (100) comprising a reduced circular model shaft (200) and a driving device (300) provided outside the test earth tank (100) and moving one of the model shafts (200). Is configured in a container shape with an open top, and a drive source storage chamber (102) is provided below the bottom surface (101). One of the model shafts (200) has a fixed shaft (20).
As 2), it is erected and fixed on the bottom surface (101) of the test soil tank (100), and the other side is lower than the through hole (103) provided on the bottom surface (101) with the lower end as the movable shaft (201). An earth pressure gauge (S11, S1) is provided at an appropriate place in the model ground (A) so as to protrude and move in the direction of contact and separation with respect to the fixed shaft (202).
, S11...) At the intersection of the peripheral surface of the moving shaft (201) and the diameter line facing the moving direction of the moving shaft (201). S1
0 ...), and the drive device (300) is a lower drive device portion (300a) housed in the drive source housing chamber (102).
And an upper drive unit (300b) provided above the model ground (A). The lower drive unit (300a) includes a motor (301) provided in the drive source storage chamber (102). And the model shaft (20) rotated by the motor (301).
A screw rod (302) oriented in a direction orthogonal to the vertical center axis of 0);
A nut (303) fixed to the lower end protruding portion of the moving shaft (201) and reciprocating by rotating the screw rod (302). The upper drive unit (300b) includes the screw rod (30).
A second screw rod (304) arranged in parallel with 2) and a portion of the movable shaft (201) protruding above the model ground (A) and being rotated by rotation of the second screw rod (304). The lower drive unit (300a) and the upper drive unit (3).
00b) means the screw rod (302) and the second screw rod (30).
4), one end of each is loosely inserted and protrudes outside the side surface of the test soil tank (100), and both protruding portions are timing belts (306).
Further, inside the reduced model circular shaft (200), a leaf spring body (203) presses against the inner peripheral surface of the reduced model circular shaft (200) to close the divided gap. , 203) is a large-scale circular shaft model experimental device. 6. A test soil tank (100) containing a model ground (A) mounted on a centrifugal force loading device (10), and 1 / n of a vertically split shape embedded in the model ground (A). The test earth tank (100) comprising a reduced circular model shaft (200) and a driving device (300) provided outside the test earth tank (100) and moving one of the model shafts (200). Is configured in a container shape with an open top, and a drive source storage chamber (102) is provided below the bottom surface (101). One of the model shafts (200) has a fixed shaft (20).
As 2), it is erected on the bottom surface (101) of the test earthen tank (100), and the other side is formed as a movable shaft (201), and the lower end protrudes downward from a through hole provided in the bottom surface (101). An earth pressure gauge (S11, S1) is provided at an appropriate position in the model ground (A) so as to be movable in the direction of contact and separation with respect to the fixed shaft (202).
, S11...) At the intersection of the peripheral surface of the moving shaft (201) and the diameter line facing the moving direction of the moving shaft (201). S1
0 ...) is placed above the model ground (A) at a suitable position, and a distance meter (S21,
S22, S23...), And the driving device (300) is a lower driving device portion (300a) housed in the driving source housing chamber (102).
And an upper drive unit (300b) provided above the model ground (A). The lower drive unit (300a) includes a motor (301) provided in the drive source storage chamber (102). And the model shaft (20) rotated by the motor (301).
A screw rod (302) oriented in a direction orthogonal to the vertical center axis of 0);
A nut (303) fixed to the lower end protruding portion of the movable shaft (201) and advanced and retracted by the rotation of the screw rod (302), and this nut (303) is moved toward and away from the fixed shaft (202). Guide rails (307, 3)
07), and the upper drive unit (300b) includes the screw rod (30).
A second screw rod (304) arranged in parallel with 2) and a portion of the movable shaft (201) protruding above the model ground (A) and being rotated by rotation of the second screw rod (304). The lower drive unit (300a) and the upper drive unit (3).
00b) means the screw rod (302) and the second screw rod (30).
4), one end of each is loosely inserted and protrudes outside the side surface of the test soil tank (100), and both protruding portions are timing belts (306).
And the like, and the lower part of the nut (303) and the moving-side shaft (201)
A displacement position measuring instrument (S31, S32) is provided above the above, and further, in the reduced model circular shaft (200), the inner peripheral surface of the reduced model circular shaft (200) is pressed. A large-depth circular shaft model experimental device containing a leaf spring body (203, 203) that closes the divided gap.