JPS5842417B2 - earth pressure gauge - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an earth pressure meter, and more particularly to an earth pressure meter for measuring soil pressure acting on underground structures such as continuous underground walls, column piles, and wells.

BACKGROUND ART Various types of earth pressure gauges have been proposed for measuring the soil pressure acting on underground structures, and some of them have been put into practical use.

These earth pressure gauges generally consist of a pressure receiving plate, a strain sensing end (strain gauge) attached to this, and an above-ground strain detector (meter) electrically connected to the strain sensing end. It is attached to a structure and placed in close contact with the ground, and measures the earth pressure acting on the underground structure from the strain on the pressure receiving plate caused by the tonosho.

Conventionally, this type of earth pressure gauge has a pressure receiving plate with a small area of 76 to 314 d, and it is often impossible to accurately sense the soil pressure due to local rock contact with the pressure receiving plate, mortar wrapping around the front surface of the pressure receiving plate, etc.

When trying to use a commercially available large-scale soil pressure gauge, new difficulties arise in terms of price and installation of the soil pressure gauge.

In addition, there are methods of pressing the pressure plate against the ground, such as the jacking method and the sheet method, but the former is very expensive as the jack buries the ground, while the latter involves attaching the pressure plate to the sheet and using it as a late fall. It is pressed against the wall using mortar pressure.
It is difficult to use it for pressure receiving plates with very large diameters, and there are also drawbacks such as mortar wrapping around.

Furthermore, commercially available soil pressure gauges are often difficult to install, depending on the reinforcement arrangement of the structure constructed underground.

In such cases, the reinforcing bars must be specially processed or a separate jig must be prepared, but commercially available soil pressure gauges are structured so that they can be used independently, so installation is not required. All of the processing and processing required for this purpose is redundant and requires double effort.

This tendency is especially strong when using commercially available large soil pressure gauges, which is economically disadvantageous.

An object of the present invention is to provide an earth pressure gauge with a simple structure that allows the area of the pressure receiving plate to be adjusted to match the soil conditions of the ground without reducing the strength of the structure built underground.

The earth pressure gauge according to the present invention has a steel frame used to determine the position of the pressure receiving plate by fixing it to a reinforcing bar cage, shaped steel, etc., the pressure receiving plate is in the shape of a closed box, and one to Two are held;
This pressure receiving plate is configured to slide toward the ground by injecting a hardening material such as cement mortar into the back surface of the pressure receiving plate through an injection port provided in a steel frame.

The steel frame accommodates the pressure plate and protects it until the steel frame is installed in a predetermined position.

This serves to prevent the pressure receiving plate from coming into direct contact with the ground and damaging the parts to which the gauge is attached.

Additionally, the steel frame also plays a role as a stress transmission mechanism for the underground structure, if necessary.

For example, in the case of a continuous underground wall, the reinforcing bar cage would be cut in the middle and the steel frame would be fixed by welding, but the reinforcing bars could be continuous through the steel frame, reducing stress transmission. Make smooth.

In addition, in the case of a well, a space for housing the pressure receiving plate is created on the wall surface, but the stress can be bypassed by connecting reinforcing bars to the steel frame and reinforcing it with the steel frame.

As a result, the steel frame can prevent the strength of the underground structure from decreasing due to the installation of the pressure plate.

For this reason, there is no limit to the size of the pressure receiving plate, and the size of the pressure receiving plate can be selected according to the soil conditions of the ground, and it can be incorporated as part of a structure built underground. , the pressure plate can be installed correctly at the desired position.

In addition, since the pressure receiving plate is extruded with a grouting material such as mortar, its adhesion to the ground is reliable, and after the injected material hardens, it also serves as a reaction force receiver for the pressure receiving plate and is useful for protecting the steel frame. .

Hereinafter, the present invention will be described in detail together with embodiments shown in the drawings.

FIGS. 1 and 2 explain one embodiment of the present invention, and show a case where the present invention is applied to a continuous underground wall.

In the figure, the reference numeral 1 indicates a reinforcing bar cage, which is connected to a steel frame 3 having a cross-sectional shape through angle members 2.

The steel frame 3 is formed into a rectangular tube shape with both ends open, and its wall thickness must be such that it can reliably transmit the stress of the reinforcing bar cage 1 and protect the pressure receiving plate.

Furthermore, the size of the steel frame 3 can be freely selected by appropriately processing the reinforcing bar cage 1 by cutting the reinforcing bars or the like.

Note that the shape of the steel frame 3 is not limited to a rectangular tube shape, but may be a cylindrical shape or other shapes.

The reference numeral 4 in the figure is a pressure receiving plate formed in the shape of a sealed case, and its peripheral surface is sealed with a solid and adhesive sealing material 5 such as grease, which is attached to a steel frame 3.
It is slidably fitted to the

The front surface of the pressure receiving plate 4 is entirely covered with a soft elastic plate 6 made of rubber or the like, and a rubber plate 7 for sealing is fixed at the sliding contact portion with the stopper 8 on the back surface.

An injection pipe 9 for pouring mortar or the like is attached to the upper end surface of the steel frame 3 and opens between stoppers 8 and 8 that restrict the insertion limit of the pressure receiving plate 4 into the steel frame 3.

Also, in some cases, muddy water may enter from the outside due to external pressure and fill the steel frame 3, so it is recommended to install a drain pipe adjacent to the injection pipe 9 between the stoppers 8 and 8. is convenient.

On the other hand, a strain gauge 10 is adhered to the front surface of the pressure receiving plate 4 inside the elastic plate 6, and this strain gauge is connected to a ground strain detector (not shown) via a lead wire 11.

In addition, when the pressure receiving plate 4 is large, it is preferable to provide a slide guide for the pressure receiving plate on the steel frame 3 so that the extrusion operation is smooth.

After the soil pressure gauge configured as described above is installed together with the reinforcing bar cage 1, injection material is injected into the back side of the pressure receiving plate 4 from the injection pipe 9 as shown in Fig. 2, and it is installed in close contact with the ground. can.

By measuring the injection pressure at this time, the contact pressure against the ground can be estimated.

The injection pressure needs to be greater than the mud water pressure at the soil pressure gauge installation location.

Once the injected material has hardened, the soil pressure can be measured immediately, but in order to measure the earth pressure acting on a continuous underground wall, it is best to push out and install a pressure plate immediately before concrete is poured.

FIG. 3 explains another embodiment of the present invention, and this embodiment shows a case where one of the earth pressure gauges is a pore water pressure gauge that extracts only pore water pressure.

That is, the pore water pressure receiving plate 12 has a water permeable membrane 13 on the front surface, and a steel plate 14 forming the front wall of the water pressure receiving plate in the form of a casing is provided with a number of through holes 15 to guide water pressure. The structure is such that water pressure is applied to the strain gauge 10 via an elastic material 16 such as the like.

Note that the use of the water permeable membrane 13 and the elastic material 16 such as sponge can be omitted by limiting the size of the through hole 15.

FIG. 4 shows a configuration in which the tonosho can be measured only on one side, and the pressure receiving plate 4 is provided only on one side, and the other side is closed off by the side wall 17.

Figure 5 shows a structure for measuring the earth pressure acting on a well in an example where it is applied to a wall other than a continuous underground wall, but in principle it has a completely similar structure.

That is, an opening 20 is provided in the wall of a cylindrical well 18 as illustrated in FIG. 6, and reinforcing bars 19 are provided within the wall.
A steel frame 3 is fixed using angle members 2, and a pressure receiving plate 4 is provided at the open end of the steel frame 3 on the ground side.

The open end of the steel frame 3 that opens inside the well 18 is closed by a partition wall 21, and the lead wire and injection pipe 9 led out through the partition wall 21 are guided through the pipe 22 buried in the well 18. through which they are led outward.

When burying a well configured in this way on-site, the piping 22 is brought into contact every time 10 ends of the well are buried,
The lead wire 11 and the injection pipe 9 may be connected through the abutting pipe 22, and then successively guided to the outside and buried in sequence.

As is clear from the above description, according to the present invention, the following results can be obtained.

(1) The area of the pressure receiving plate can be selected to match the soil conditions of the ground without reducing the strength of the underground structure.

This improves measurement accuracy, expands the ground conditions under which earth pressure can be measured, and can be applied to a wide range of changes in ground soil conditions, structure construction conditions, etc., and improves construction safety management and design. Useful for collecting materials.

(2) Since the steel frame of the soil pressure gauge constitutes a part of the underground structure, the soil pressure gauge can be placed in the correct position in a rational and economical manner, and the pressure receiving plate is placed underground. It adapts well to the shape of the structure, making it possible to measure earth pressure in accordance with the actual situation.

(3) Since the structure is simple, it can be manufactured in a short delivery time and is inexpensive.

Therefore, the size of the pressure receiving plate can be relatively large and arbitrarily selected.

(4) Sensitivity can be freely selected by appropriately selecting the thickness of the pressure receiving plate and the strain gauge.

(5) The elastic plate attached to the front of the pressure plate protects the strain gauge and disperses the concentrated force acting from the ground, improving the reliability of measurement results.

(6) Since the injection pressure of the injection material is used to extrude the pressure receiving plate, the operation is as smooth as hydraulic operation, and it firmly adheres to the ground, is inexpensive, and has no failures.

[Brief explanation of drawings]

Figures 1 and 2 are a perspective view and a vertical side view illustrating an example of an earth pressure gauge applied to a continuous underground wall, Figure 3 is a vertical side view when a pore water pressure gauge is installed, and Figure 4 FIG. 5 is an enlarged sectional view showing an example in which a pressure receiving plate is provided on only one side, FIG. 5 is an enlarged sectional view when installed in a well, and FIG. 6 is a perspective view showing an example of a well. 1...Reinforced cage, 2...Angle material, 3
...Steel frame, 4...Pressure plate, 5...
...Sealing material, 6.7...Elastic plate, 8...
...Stopper, 9...Injection pipe, 10...
...Strain gauge, 11...Lead wire,
12... Pore water pressure receiving plate, 13... Water permeable membrane, 14... Steel plate, 15... Through hole,
16...Elastic material, 17...Side wall, 18
...Well, 19...Reinforcement bar, 20...
...opening, 21...partition wall, 22...
···Piping.

Claims (1)

[Scope of Claims] 1. An earth pressure meter in which a pressure receiving plate is attached to an underground structure and brought into close contact with the ground, and the soil pressure acting on the underground structure is measured by the strain of the pressure receiving plate. A cylindrical steel frame that penetrates the reinforcing material, is fixed to the reinforcing material, is equipped with an inlet for hardening material, and opens vertically toward the ground surface; A pressure receiving plate of a sealed casing that is slidably fitted without being sealed between the steel frame and is extruded by injecting the hardening material from the injection port, and is attached to a plate on the ground side of the pressure receiving plate. An earth pressure gauge comprising a strain gauge mounted on the ground and a strain detector on the ground electrically connected to the strain gauge. 2. The earth pressure gauge according to claim 1, wherein the opening of the steel frame is provided on one or both end faces. 3. The earth pressure gauge according to claim 2, wherein an elastic plate is attached to the front surface of the plate on the ground side of the pressure receiving plate. 4. Claim 2, wherein the reinforcing bar is a reinforcing bar cage, and the steel frame is welded to the reinforcing bar cage directly or through a shaped steel material.
Soil pressure gauge as described in paragraph or paragraph 3. 5. The earth pressure gauge according to claim 2, 3, or 4, wherein the steel frame has a drainage port adjacent to a hardening material injection port.