JP6970404B2 - Peripheral friction meter - Google Patents

Description

The present invention relates to a peripheral friction meter for measuring the frictional force between the caisson peripheral surface and the peripheral surface ground.

Conventionally, when constructing a structure in the ground, a construction method is used in which a caisson constructed on the ground is subsided in the ground.
At this time, in order to sunk the caisson with high accuracy, it is necessary to measure the frictional force between the caisson peripheral surface and the peripheral surface ground.

A peripheral friction meter for measuring frictional force consists of an outer frame that is embedded and fixed in a caisson and an inner frame that fits into the outer frame. And it is attached to the inner frame (Fig. 9).
Both ends of the leaf spring are fixed to the outer frame, and the inner frame is supported by the leaf spring.
The leaf spring is arranged with a gap between it and the outer frame except for both ends so that the leaf spring is elastically deformed according to the displacement of the inner frame.

In recent years, the deep caisson method has come to be used, and when the depth is large, a large earth pressure acts on the peripheral friction meter.
When the earth pressure acting on the inner frame becomes large, the leaf spring is plastically deformed due to the gap between the leaf spring supporting the inner frame and the outer frame, and the frictional force cannot be measured correctly.

An object of the present invention is to provide a peripheral friction meter capable of accurately measuring a frictional force even at a large depth.

The first invention of the present application made to achieve the above object is a box-shaped outer frame having an open top surface fixed to the peripheral surface of a structure, an inner frame fitted to the upper surface of the outer frame, and the outer frame. inside place of, and sensitivity portion for detecting a frictional force acting on the frame consists, and the sensitivity portion is separate from, the bottom surface or the outside the frame of any one of the upper or lower end It is fixed to one of the inner bottom surfaces of the frame, the other end is not connected to either the bottom surface of the inner frame or the inner bottom surface of the outer frame, and the lower end is in contact with the inner bottom surface of the outer frame and acts on the inner frame. Provided is a peripheral friction meter having a load support portion for supporting a load downward on the outer frame.
According to the second invention of the present application, in the peripheral friction meter of the first invention, the load supporting portion is made of a columnar or plate-shaped steel material and is arranged between the bottom surface of the inner frame and the inner bottom surface of the outer frame. Provided is a peripheral friction meter characterized by.
According to the third aspect of the present invention, in the peripheral friction meter of the second invention, one end of the load support portion is fixed to either the bottom surface of the inner frame or the inner bottom surface of the outer frame, and a cushioning material is provided at the other end. Provided is a peripheral friction meter characterized by being attached.

The present invention can obtain the following effects by means for solving the above-mentioned problems.
(1) by supporting the load of the outer frame lower surface Direction acting on the inner frame by the load supporting portion, the plastic deformation of the sensitive portion by earth pressure is suppressed.
(2) Since the plastic deformation of the sensitivity portion is suppressed, it can be used even in a deep caisson method in which a large earth pressure acts.
(3) By attaching the cushioning material to the contact surface between the load support portion and the inner frame or the outer frame, the load support portion does not hinder the horizontal displacement of the inner frame.

Explanatory drawing of peripheral friction meter of this invention (1) Explanatory drawing (2) of peripheral friction meter of this invention Explanatory drawing (3) of peripheral friction meter of this invention Explanatory drawing (4) of peripheral friction meter of this invention Explanatory drawing of peripheral friction meter concerning Example 2 Explanatory drawing (1) of peripheral friction meter concerning Example 3 Explanatory drawing (2) of peripheral friction meter concerning Example 3 Explanatory drawing of peripheral friction meter concerning Example 4 Explanatory drawing of the conventional peripheral friction meter

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

<1> Circumferential Friction Meter The peripheral friction meter of the present invention is fixed to the surface of a structure C such as a caisson and measures the frictional force between the structure C and its peripheral ground.
The soil pressure gauge of the present invention includes an outer frame 1 fixed to the structure C and an inner frame 2 fitted to the outer frame 1 (FIG. 1).
The outer frame 1 has a box shape with an open top surface and is embedded in the structure C.
The inner frame 2 is a flat plate having substantially the same dimensions as the open upper surface of the outer frame 1, and is fitted with the outer frame 1 to be flush with the surface of the structure 2.

<2> Sensitivity section The sensitivity section 3 includes two leaf springs 31 having both ends fixed to the outer frame 1, a connecting section 32 connecting the leaf spring 31 and the inner frame 2, and a load cell 33.
When a frictional force acts on the inner frame 2, the inner frame 2 is displaced with respect to the outer frame 1 due to the frictional force, and the displacement is detected by the load cell 33 to measure the frictional force.
Both ends of the leaf spring 31 are fixed to the outer frame 1 in a state of being floated from the inner bottom surface of the outer frame 1 so as to be elastically deformed according to the displacement of the inner frame 2.

<3> Load support portion The load support portion 4 is a member that supports a load in the lower surface direction of the outer frame 1 generated by the action of earth pressure on the inner frame 2.
The load support portion 4 in this embodiment is a columnar steel material, and four are evenly distributed and arranged at positions that do not interfere with the sensitivity portion 3.
The load supporting portion 4 has a height substantially the same as the distance between the inner bottom surface of the outer frame 1 and the bottom surface of the inner frame 2, and the bottom surface is fixed to the inner bottom surface of the outer frame 1.
The upper surface of the load supporting portion 4 and the inner frame 2 may be in contact with each other, or there may be a gap as long as it is within the range of elastic deformation of the leaf spring 31.
When earth pressure acts on the inner frame 2 and the inner frame 2 moves into the outer frame 1 and comes into contact with the upper surface of the load support portion 4, it is supported by the load support portion 4 and the inner frame 2 may be pushed further. No.
As a result, the plastic deformation of the leaf spring 31 is suppressed, and the peripheral friction can be measured even when a large earth pressure acts.

<3.1> Shape of load-bearing portion The load-bearing portion 4 may be a flat plate-shaped plate (FIG. 2) or a plate having flanges at the top and bottom (FIG. 3).

<4> Cushioning material A cushioning material 41 may be attached to the upper surface of the load supporting portion 4. As the cushioning material 41, rubber such as chloroprene, a Teflon (registered trademark) sheet, or Teflon tape is suitable.
By arranging the cushioning material 41 between the load support portion 4 and the inner frame 2, the inner frame 2 is not pressed against the load support portion 4 and the displacement in the horizontal direction is not hindered.
Further, the load supporting portion 4 may have a shape continuous in the displacement direction of the inner frame 2 and a flat roller 42 may be provided on the upper surface (FIG. 4).

In the above embodiment, the load support portion 4 is fixed to the inner bottom surface of the outer frame 1, but it may be fixed to the bottom surface of the inner frame 2. At this time, the cushioning material 41 is arranged between the load supporting portion 4 and the outer frame 1.

In this embodiment, the load support portion 4 is a sphere (FIG. 5).
The load support portion 4 fixes a ring-shaped pedestal 43 to the inner bottom surface of the outer frame 1 and holds the spherical load support portion 4 in the pedestal 43.
The load support portion 4 can move freely in the pedestal 43.

In this embodiment, the load support portion 4 is an elastic body, and is a coil spring (FIG. 6) or a leaf spring (FIG. 7). In the case of a leaf spring, a fixing portion 44 is formed and fixed on the inner bottom surface of the outer frame 1, and a sliding portion 45 is formed on the bottom surface side of the inner frame 2 and slides according to the deformation of the leaf spring.

In this embodiment, the load supporting portion 4 has a rod shape and is fixed to the inner side surface of the outer frame 1 to support the inner frame 2 (FIG. 8).

1 Outer frame 2 Inner frame 3 Sensitivity part 31 Leaf spring 32 Connecting part 33 Load cell 4 Load support part 41 Cushioning material 42 Flat roller

Claims (5)

A box-shaped outer frame with an open top that is fixed to the peripheral surface of the structure,
An inner frame that fits on the upper surface of the outer frame and
It consists of a sensitivity unit that is placed inside the outer frame and detects the frictional force acting on the inner frame.
It is a separate body from the sensitivity unit, and one end of either the upper end or the lower end is fixed to either the bottom surface of the inner frame or the inner bottom surface of the outer frame, and the other end is the bottom surface of the inner frame and the outer frame. A peripheral friction meter having a load support portion that is not connected to any of the inner bottom surfaces, has a lower end in contact with the inner bottom surface of the outer frame, and supports a load downward on the outer frame acting on the inner frame. In the peripheral friction meter according to claim 1,
A peripheral friction meter, characterized in that the load bearing portion is made of a columnar or plate-shaped steel material. In skin friction meter according to claim 2, wherein the load-bearing part is characterized by attaching a buffer material other end, the peripheral surface tribometer. In the peripheral friction meter according to claim 1,
A peripheral friction meter, characterized in that the load supporting portion is a sphere. In the peripheral friction meter according to claim 1,
A peripheral friction meter, characterized in that the load supporting portion is an elastic body.

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