JP3519190B2 - Eccentric plate loading method and device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for loading an eccentric flat plate on the ground, and more particularly to a method and apparatus for loading an eccentric flat plate used in a test for evaluating the strength and deformation characteristics of the ground against an eccentric load. is there.

[0002]

2. Description of the Related Art In order to estimate the bearing capacity-subsidence relationship of foundation structures of long bridges and other various structures, for example, in a working room of a pneumatic caisson, a bearing capacity test is conducted to determine the vertical ground reaction coefficient and , A test may be conducted to check the ground condition for ultimate bearing capacity.

Conventionally, this ground proof test is carried out by the method shown in FIG. The figure shows a test device installed in the working room of a pneumatic caisson, and a loading plate (hereinafter referred to as a flat plate) 2 made of a steel disk having a thickness of 22 mm and a diameter of 300 mm is mounted on the surface of the ground 1 in this working room. The hydraulic jack 13 and the support pipe 14 are sequentially stacked on the flat plate 2, and the upper end of the support pipe 14 is in contact with the ceiling slab reaction force receiving surface 3 of the working chamber via the pipe camber 15. The hydraulic jack 13 is connected to the pump 12 via a pipe 17. In addition, a supporting leg 16 is provided on the surface of the ground 1 which is separated from the loading flat plate diameter by three times or more, and by this supporting leg 16
The beam member 18 made of steel is supported, and the dial gauge 19 provided on the flat plate 2 and the flat plate 20 provided on the beam member 18 are connected.

In order to carry out a load test with the above-mentioned apparatus, first, the flat plate 2 is made to adapt to the ground 1. Therefore, a load of about 1/10 of the expected yield load is applied to the flat plate 2 and then the load is temporarily removed to obtain a dial gauge. The number 19 is read and used as the origin of displacement. Next, a load of about 1/10 of the expected yield load is applied to the flat plate 2, and the load strength and the subsidence amount of the ground 1 are read. Immediately increase the load to the next load stage and continue measurement. Repeated loading is 1/2 of expected yield load
Perform near the load. This load test is normally performed until the load-squat curve approaches the squat axis or the load strength exceeds the yield point of the ground, and the test is terminated there. When the load increases without reaching the yield point, the flat plate 2
The test may be terminated when the amount of subsidence reaches 10% of the loading flat plate diameter.

In the above-mentioned loading test, since a vertical load is applied to the central portion of the flat plate 2, the central portion of the flat plate 2 is pressed by using a single hydraulic jack 13, and there is no particular problem. However, in order to test the strength of the ground against an earthquake or the like, a vertical load may be applied to the eccentric position of the flat plate 2 as shown in FIGS. 13 and 14, and in this case, the conventional method shown in FIG. However, there was a problem that proper testing could not be performed with this test device. That is, in FIG. 13, on the upper surface of the flat plate 2 and from the center line O of the flat plate, a distance e
Place one hydraulic jack 13 at a position eccentric only
When the hydraulic jack 13 is extended by applying a reaction force to the ceiling slab reaction force receiving surface 3 and a test is performed using the same measuring means as shown in FIG. 12, a load is applied to the eccentric position of the flat plate 2. Therefore, the flat plate 2 inclines as shown in FIG. 14, and the hydraulic jack 13 inclines accordingly. However, when the hydraulic jack 13 extends in a tilted state as shown in FIG. 14, the load direction of the hydraulic jack 13 also tilts to become a tilted load, and the eccentric amount e ′ of the load applied to the tilted flat plate 2 is eccentric vertically. Eccentricity e of initial load e
However, e ≠ e '. That is, the flat plate 2 is kept under the condition that the amount of eccentricity is constant between the initial load loading and the load loading.
It is difficult to apply a vertical load to the ground to smoothly perform a ground bearing test against the withstand load of the ground 1.

[0006]

In order to test the earth bearing capacity when a vertical load is applied when the position of the center of gravity is displaced due to a horizontal moment, such as during an earthquake,
There has been no method and means for applying a vertical load to the eccentric position of the flat plate 2 to perform an appropriate test.

In order to solve the above problems, it is an object of the present invention to provide a method and apparatus capable of properly applying an eccentric vertical load to a flat plate.

[0008]

In order to achieve the above-mentioned object, in the method for testing the loading of a flat plate of the ground according to the present invention, the ground 1
Is installed on the upper surface of the flat plate 2 placed on the upper side of the center line O so as to be pivotally displaceable with respect to the flat plate 2 on both sides thereof, and the top of the jack can be horizontally moved to a horizontal ceiling. The eccentric vertical load-bearing fluid pressure jacks 4 and 4A, which are directly or indirectly abutted on the slab reaction force receiving surface 3, apply a reaction force to the ceiling slab reaction force receiving surface 3 to oppose the eccentric side. The eccentric vertical load is applied to the resultant point p of the eccentricity e of the flat plate 2 by applying pressure with a pressure difference at a predetermined ratio regardless of the inclination of the flat plate 2. Further, the eccentric flat plate loading apparatus according to the present invention sandwiches the center line O on the upper surface of the flat plate 2 placed on the ground 1, and mounts the eccentric vertical load loading fluid pressure jacks 4 and 4A on both sides of the center line O via the mounting brackets 5. ,
The fluid pressure jacks 4 and 4A are installed so as to be rotatable and displaceable with respect to the flat plate 2, and the extendable top end of the fluid pressure jacks 4 and 4A is provided through a roller 6 that is horizontally rollable or a sliding friction bearing that can reduce frictional force. It is characterized in that it directly or indirectly abuts on the horizontal ceiling slab reaction force receiving surface 3. Between the fluid pressure jacks 4 and 4A on the opposite side to the eccentric side forming the pair, both ends of the connecting plate 7 may be connected by connecting fittings 11 which are connected to the cylinders 10 and 10A via connecting shafts 8.

According to the present invention, even if the flat plate 2 inclines due to the loading of the eccentric vertical load, the paired eccentric vertical load loading hydraulic jacks 4 and 4A are in the vertical state without the mounting position of the flat plate 2 being displaced. Therefore, the distance from the resultant force point p to the center line O, that is, the amount of eccentricity e does not change even if the flat plate 2 is tilted, and thus the smooth eccentric vertical direction from the ceiling slab reaction force receiving surface 3 to the flat plate 2 is obtained. The load can be transmitted.

[0010]

1 and 2 are views structurally showing the principle of the present invention. In each figure, two eccentric vertical load loading fluid pressure jacks 4 and 4A are arranged on the upper surface 2A of the flat plate 2 arranged on the ground at a position separated from the center line O of the flat plate 2 by a predetermined distance. There is. This fluid pressure jack 4, 4
The lower end of the cylinder 10 of A is connected via a bearing pin 21 to a mounting member 5 whose upper and lower parts are rotatably supported, and the mounting member 5 is fixed to the upper surface 2A of the flat plate 2. To the flat plate 2 with the fluid pressure jacks 4 and 4A
Is rotatably mounted with the support pin 21 as a fulcrum.
The piston rod 9 of each of the fluid pressure jacks 4 and 4A is provided with a roller receiving plate 23, and a plurality of rollers 6 provided on the upper surface of the roller receiving plate 23 are provided on the ceiling slab reaction force receiving surface 3. It presses freely to roll. Therefore, the upper ends of the fluid pressure jacks 4 and 4A are in contact with the ceiling slab reaction force receiving surface 3 through the plurality of rollers 6 so as to be horizontally movable with almost no frictional resistance.

In the present invention, by changing the ratio of the pressures applied to the left and right fluid pressure jacks 4 and 4A arranged as a pair, a vertical load is applied to a position e which is eccentric from the center line O of the flat plate 2. be able to. FIG. 1 shows an initial state of eccentric vertical load loading by the two fluid pressure jacks 4 and 4A. From the state shown in FIG. 1, large and small pressures are applied to the left and right fluid pressure jacks 4 and 4A, and this pressure is gradually increased with the pressure ratio kept at a predetermined ratio.
When the value of the eccentric vertical load applied to is increased, the eccentric side fluid pressure jack 4A expands more than the anti-eccentric side fluid pressure jack 4 as shown in FIG. 2, and the flat plate 2 is subjected to the eccentric load. Slope / horizontal movement to the side where

According to the present invention, as shown in FIGS. 1 and 2, when the flat plate 2 is displaced from the horizontal state to the inclined state with the increase of the eccentric vertical load, the fittings 5 for mounting the fluid pressure jacks 4 and 4A on the flat plate 2 are provided. The mounting position via is the same as that at the initial stage of loading the eccentric load. At this time, the fluid pressure jacks 4,
The contact position between the top end of 4A and the ceiling slab reaction force receiving surface 3 is displaced in order to hold the fluid pressure jacks 4 and 4A vertically regardless of the inclination of the flat plate 2. The piston rod 9 of the jacks 4 and 4A is a rolling roller 6
By contacting with the ceiling slab reaction force receiving surface 3 via, the contact position of the fluid pressure jacks 4 and 4A with respect to the ceiling slab reaction force receiving surface 3 is freely displaceable. Even if the fluid pressure jacks 4 and 4A are tilted, the fluid pressure jacks 4 and 4A can maintain a vertical posture while moving horizontally, and the distance between the resultant point p of the fluid pressure jacks 4 and 4A and the center line O, that is, the eccentricity e changes. Therefore, the desired eccentric vertical load can be smoothly applied to the inclined flat plate 2.
3 to 8 show the present invention more specifically, in which a loading board 22 is installed on the ground 1, and the loading board 22 is arranged in pairs on the upper flat plate 22A on the left and right sides. The eccentric vertical load loading fluid pressure jacks 4 and 4A are arranged in seven sets, and the first upper reaction plate 24 and the second upper reaction plate 24 are mounted on the top end of the fluid pressure jacks 4 and 4A via the roller 6. The power boards 25 are arranged in an overlapping manner, and the second upper reaction board 25 is in contact with the ceiling slab reaction force receiving surface 3. First and second upper reaction plates 24, 2
5 is for filling the space between the tops of the fluid pressure jacks 4 and 4A and the ceiling slab at the time of the actual load test. Therefore, FIGS.
In the case of (1), the ceiling slab reaction force receiving surface 3 (that is, according to the claims) is in contact with the top end of the fluid pressure jacks 4 and 4A via the roller 6, and the first upper reaction force receiving plate 24 is provided. Is the lower end surface of.

The loading plate 22 has an upper flat plate 22A having a rectangular shape in plan view, and for the convenience of a loading test.
In order to secure the height position of installation of the fluid pressure jacks 4 and 4A from the ground 1, the upper flat plate 22A has a vertical wall 22C having a predetermined height formed by reinforcing the outer surface with a plurality of vertical parallel reinforcing plates 26.
Is fixed to the upper part of the vertical wall 22C, and the lower flat plate 22B provided at the lower end of the vertical wall 22C is in direct contact with the ground 1.
The eccentric vertical load loading hydraulic jacks 4 and 4A are paired on both sides in the longitudinal direction of the upper flat plate 22A, and are rotated at predetermined intervals through 7 sets (a total of 14 left and right) bearing pins 21. It is erected freely. More specifically, the lower member 5B, which is rotatably coupled to each other by the support pin 21 of the mounting member 5, is fixed to the upper flat plate 22A by a fixing means such as welding or bolt 39 fastening. Further, the split fastening member 2 having the semicircular recess 27 in the upper member 5A of the mounting member 5
8 is fixed with bolts 40 and nuts, fluid pressure jack 4,
Fit the lower end of the 4A cylinder 10 into the semi-circular recess 27,
The fluid pressure jacks 4 and 4A can be fixed to the mounting member 5 by tightening the joint portion of the split fastening member 28 with the bolt 29 and the nut 30. In order to prevent the fluid pressure jacks 4 and 4A from falling when installed, the bolt 39 of FIG.
Is extended as a long bolt downwardly, and thereby the upper member 5A and the lower member 5B of the mounting member 5 are detachably connected so that they are not rotated about the bearing pin 21 (however, it is preferable that (Not shown). A roller receiving plate 23 is placed on the upper part of the plunger 9 which is provided so as to be capable of expanding and contracting upward from the cylinder 10 via a height adjusting member 31 composed of a plurality of loading plates or steel materials, and each roller. A plurality of rollers 6 are arranged on the upper surface of the receiving plate 23. Roll 6 is φ17m
m, pC steel material with a length of about 200 mm is used, and the arrangement is such that fluid pressure jacks 4 and 4 with axes on the left and right respectively.
It is provided so as to be parallel to the arrangement direction of A. Further, the left and right fluid pressure jacks 4 and 4A are connected by a connecting fitting 11 so that the left and right fluid pressure jacks 4 and 4A can be displaced while maintaining a vertical posture without falling when the loading board 22 is inclined. The connecting metal fitting 11 is arranged along the circumference of the cylinder 10 and is annularly fastened with a bolt 29 and a nut 30 constituting the connecting shaft 8 and both ends thereof are pivotally coupled to the annular portion 32 by the bolt 29. And a connecting plate 7.

The connecting fittings 11 may not be provided in all the pairs of fluid pressure jacks 4 and 4A, but may be provided in arbitrary pairs which are located at appropriate intervals. In that case, Left and right fluid pressure jacks 4 and 4, 4A
It is preferable to connect the parts 4 and 4A with each other by using a long connecting member (not shown).

In this way, since the left and right fluid pressure jacks 4 and 4A are connected by the connecting fittings 11, they do not fall or tilt, and in addition, in the state where they are held in the vertical posture, they can cope with the displacement of the distance between them. it can.

The first upper reaction plate 24 and the second upper reaction plate 25
For the convenience of the configuration of the test apparatus, the above-mentioned serves as a spacer for ensuring a space between the ceiling slab reaction force receiving surface 3 and the fluid pressure jacks 4 and 4A. Vertical walls 24A and 25 reinforced by reinforcing plates 33
It is configured to have horizontal portions 24B, 24C, 25B, 25C above and below A, and the first and second upper reaction plates 24, 25 are placed in a layout in which their longitudinal directions are orthogonal to each other. ing.

An upper end of a vertical reference beam 35 is fixed to the ceiling slab reaction force receiving surface 3 via anchor bolts 34. A horizontal reference beam 36 is attached to a lower portion of the vertical reference beam 35, and a horizontal reference beam 36 is attached. A displacement gauge 37 is installed between the hydraulic pressure jack 4 and the cylinder 10 of the fluid pressure jack 4A via a working rod 38.

Therefore, in the flat plate loading test apparatus for the ground 1, a fluid pressure is applied from a pressure fluid supply device (not shown) to the fluid pressure jacks 4 and 4A on the side opposite to the eccentric side at a predetermined pressure ratio, and the center of the loading board 22 is moved. An eccentric vertical load is loaded at a position deviated from the fluid pressure jack by a predetermined amount, the tilt amount of the loading plate 22 is measured by the displacement gauge 37, and the fluid pressure jacks 4 at that time are measured.
It is possible to measure the support strength of the ground 1 against the eccentric vertical load smoothly and with high accuracy by comparing the magnitude of the pressure applied to 4A and the predetermined calculation formula.

[Example] The present inventors conducted a load test according to the above-mentioned method, which will be described below. In the present invention, a pair of eccentric vertical load loading hydraulic jacks 4,
In order to measure the magnitude of the eccentric vertical load applied to the flat plate 2 based on the magnitude of the resultant force of 4A, the measurement is performed based on FIGS. 9 and 10 and the mathematical formulas described below.

First, in carrying out the eccentricity loading test, it is the most important task to carry out the loading while keeping the eccentricity amount constant. Here, the oblique distance shown in FIG. 9 is defined as the eccentricity amount. In FIG. 10, N1: Eccentric vertical load loading fluid pressure jack on the side opposite to the eccentric side N2: Eccentric side eccentric vertical load loading fluid pressure jack e: Eccentricity (0.3B) H: Flat plate (loading plate) ) Height from bottom end to bearing pin θ: Flat plate inclination angle L: Distance between flat plate center line and bearing pin Loading point (distance from center line at top of flat plate): xx = e-H · tan θ Moment generated: MM = (e−H · tan θ) cos θ × N Moment generated at jack installation position: M ′ M ′ = − N1 × L · cos θ + N2 × L · cos θ = L · cos θ ( N2-N1) However, N = N1 + N
22 In order for the two-point load and the concentrated load to be equal, it is sufficient that M = M ′ (e−H · tan θ) cos θ × N = L · cos θ (N2-N
1) When sorted by N1 and N2, the jack distribution load calculation formula for keeping the eccentricity constant is as follows. N1 = − (e−H · tan θ−L) × N / 2L N2 = (e−H · tan θ + L) × N / 2L As a result of examination according to FIG. 10, the flat plate shape is H =
It became 0.59m L = 0.31m.

Under the above conditions, the maximum tilt angle that can hold e = 0.3B is 36 °, and the maximum tilt angle of the loading device body is 40 °.
(See 3.3), and it was judged to be appropriate for this test. Table 1 and Table 2 (θ ≦ 40 °) show each distributed load of the jack. From this, the allowable tilt angle under ultimate load can be changed to CASEI, II, II.
Assuming that I is 0 to 2 ° and 2 to 31 °, respectively, N1
It was judged that the maximum loads of 350 tf and 400 tf are required for N2 and 350 tf and 300 tf for N2, respectively. 31-
If it is determined that the angle is up to 36 °, move the jack to deal with it. Note that FIG. 11 shows a flowchart for determining the height and position of the loading action point.

[Table 1]

[Table 2]

[0022]

As described above, according to the present invention,
It is attached to the flat plate 2 so as to be rotatable at a fixed position, and
The horizontal ceiling slab reaction force receiving surface 3 is abutted so as to be horizontally movable via rollers or sliding friction bearings capable of reducing frictional force, and the center line O of the flat plate 2 is sandwiched to form a pair on both sides thereof. Even if the flat plate 2 is tilted, the eccentric vertical load loading fluid pressure jacks 4 and 4A arranged in the flat plate 2 maintain the vertical posture of the fluid pressure jacks 4 and 4A.
An eccentric vertical load can be applied to the flat plate 2, so that even if the flat plate 2 is tilted, the fluid pressure jacks 4 and 4A are moved from the center line O thereof.
To the resultant force point p, that is, the amount of eccentricity e can always be kept constant. Therefore, there is an effect that the eccentric vertical load can be smoothly applied to the flat plate with a simple device.

[Brief description of drawings]

FIG. 1 is an explanatory view showing a basic structure of the present invention and showing an initial loading of an eccentric vertical load on a flat plate.

FIG. 2 is an explanatory diagram showing when an eccentric vertical load is applied to a flat plate.

FIG. 3 is a side view of the eccentric flat plate loading apparatus according to the present invention.

4 is a cross-sectional view taken along the line AA of FIG.

FIG. 5 is a front view of FIG.

FIG. 6 is a plan view of FIG.

FIG. 7 is an enlarged vertical sectional view of a portion of FIG. 3A.

FIG. 8 is an enlarged cross-sectional view of the portion shown in FIG. 3A.

FIG. 9 is a diagram illustrating the definition of the amount of eccentricity in the present invention.

FIG. 10 is a diagram illustrating distribution of a load amount on a flat plate.

FIG. 11 is a flow chart for implementing the method of the present invention.

FIG. 12 is an explanatory diagram of a conventional vertical load loading device for a loading flat plate.

FIG. 13 is an explanatory diagram showing a state of an eccentric vertical load on a flat plate at the beginning of loading by a conventional device.

FIG. 14 is an explanatory diagram showing a state when an eccentric vertical load in FIG. 13 is loaded.

[Explanation of symbols] 1 ground 2 flat plates 2A Flat plate top 3 Ceiling slab reaction force receiving surface 4,4A eccentric vertical load fluid pressure jack 5 Mounting bracket 5A upper member 5B lower member 6 roller 7 connecting plate 8 connecting pins 9 piston rod 10 cylinders 11 Connecting bracket 12 pumps 13 hydraulic jack 14 Strut pipe 15 pipe camber 16 Support legs 17 Piping 18 Beam material 19 dial gauge 20 flat plate 21 Bearing pin 22 loading board 22A upper flat plate 22B Lower plate 22C vertical wall 23 Roll receiving plate 24 1st upper reaction board 24A vertical wall 24B Upper horizontal part 24C lower horizontal part 25 Second upper reaction plate 25A vertical wall 25B Upper horizontal part 25C lower horizontal part 26 Vertical parallel reinforcing plate 27 Semicircular recess 28 split fastening members 29 Volts 30 nuts 31 Height adjustment member 32 annular part 33 Vertical parallel reinforcing plate 34 Anchor bolt 35 Vertical Reference Beam 36 Horizontal reference beam 37 Displacement meter 38 Working Rod 39 volts 40 volts

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-60-91234 (JP, A) JP-A-57-139641 (JP, A) Actual development Sho-59-49946 (JP, U) (58) Field (Int.Cl. ⁷ , DB name) G01N 3/00 E02D 1/02

Claims (2)

(57) [Claims] 1. A top surface of a flat plate 2 placed on the ground 1, and on both sides of a center line O sandwiching the center line O, the pair of flat plate 2 is rotatably displaceable with respect to the flat plate 2. A reaction force is applied to the ceiling slab reaction force receiving surface 3 by the eccentric vertical load loading fluid pressure jacks 4 and 4A that are directly or indirectly abutted on the horizontally movable ceiling slab reaction force receiving surface 3. The flat plate 2 is irrespective of the inclination of the flat plate 2 by applying pressure with a pressure difference at a predetermined ratio between the eccentric side and the opposite side.
The eccentric flat plate loading method is characterized in that an eccentric vertical load is applied to a resultant force point p of the eccentric amount e. 2. On the upper surface of the flat plate 2 placed on the ground 1, on both sides of the center line O, the fluid pressure jacks 4 and 4A for eccentric vertical load loading are attached to the flat plate 2 via the fittings 5. A horizontal ceiling slab that is installed so as to be rotatable and displaceable, and that has a retractable top end of the fluid pressure jacks 4 and 4A through a roller 6 that is horizontally rollable or a sliding friction bearing that can reduce frictional force. An eccentric flat plate loading device characterized in that it is brought into direct or indirect contact with the reaction force receiving surface 3.