JPH0355628Y2 - - Google Patents

Description

[Detailed Description of the Invention] A. Purpose of the Invention A. Field of Industrial Application This invention aims to provide an anchor pin that can prevent the phenomenon of frozen soil adhesion or frost heaving.

B. Conventional technologies and their problems Although there has been significant progress in the slope construction method with edging for slope protection and the netting construction method for rockfall protection, which are the main targets of this proposal, in recent years It is used to secure these structures to slopes.

Steel anchor pins are falling off and floating more and more, and in some places, anchors become ineffective and slopes collapse, or slopes slide down, destroying structures and causing traffic problems. It's becoming a problem.

The results of the investigation into the causes show that, excluding design and construction errors, there are striking regional differences; such accidents and failures do not occur in warm areas where soil does not freeze; Stay awake and focused.

According to research, this is caused by the phenomenon of frozen soil adhering to the anchor pins when the soil expands in volume due to freezing, or by frost heave.

It has been found that the deeper the freezing depth, the more intense the frost heaving.The amount of frost heaving varies depending on various conditions such as soil quality, water content, amount of water supply, and temperature, but it is roughly 10% of the freezing depth. It is said to be ~15%.

Observation results from various locations have been announced that are close to the same.

In addition, the ground frost heaving force changes depending on various conditions, but it has been observed to be 23 to 55 kg per cm ² , which shows that it is a very large force.

Furthermore, the force with which frozen soil adheres varies depending on various conditions, but it is said to be 1 to 2.3 kg/cm ² .

Anchor pins driven into slopes by freezing of the soil are lifted by a strong force, and it is known that the amount of force is approximately equal to the amount of frost heaving of the ground.

The bases of these lifted anchor pins become voids, but due to infiltration of snowmelt in early spring and movement of unfrozen water in the ground during winter, soil around the voids flows in and fills the voids, causing the frozen soil to thaw. An anchor pin that has been released from restraint cannot return to its original position, and as this process is repeated, the amount of floating of the anchor pin increases over time, and eventually it falls off or loses its ability to function as an anchor. effect is lost.

B. Structure of the invention A. Means for solving the problem The present application attempts to solve the above-mentioned problem with the following structure.

That is, the anchor pin of the present application has a heat-shrinkable polyvinyl chloride resin tube covered over the pin body, the lower end of the tube is brought into close contact with the pin, and the head is covered with a cap.

In this case, steel foils 7 can be glued to the back and front sides of the head of the cap.

B. Example To put it simply, the concept of this proposal is similar to the relationship between a sword and a scabbard.

If you hold down the scabbard with a slight force and pull out the sword, the sheath will remain in its original position; in the opposite case, if you hold down the blade and pull out the sheath, the blade will remain in that position and the sheath will fall out. .

This is used in anchor pins used in areas where frozen soil adheres or frost heave occurs, and the tubes made of heat-shrinkable polyvinyl chloride resin are used to act as sheaths. This is attached to the steel anchor pin body 1.
(16m/m - 30m/m) If you cover up to half of the length and heat the bottom end with a suitable heater (130℃),
The heated portion of the tube rapidly contracts and tightly attaches to the steel anchor pin.

Figure 1 shows a side cross-section of the anchor pin A made in this way. 2 is a tube made of polyvinyl chloride resin, and 3 is a portion that is heated and shrunk and is in close contact with the pin. A cap 4 made of the same material as the tube is placed over the head of the steel anchor pin 1 to which the bottom end of the tube is tightly attached.

Steel thin strips 7 are attached to the back and front sides of the head of this cap.
is glued.

The purpose of covering the cap is to prevent rain from entering the gap between the pin and the tube and freezing during the cold season.The purpose of gluing the thin steel strips 7 on the front and back of the head is to cover the cap when driving the anchor pin. This is to serve as a protective plate to prevent damage to the material.

This cap is shrunk by heating at a low temperature so that it will not easily fall off during transportation or handling.

C Effect Explain along with the effects.

C. Effect of the invention The anchor pins made in this way are driven into the soil at the intersection of the concrete frame 6 as shown in Figure 4 and in the ground as shown in Figure 3 to fix the concrete frame 6 to the slope.

5 in Figure 3 indicates the soil freezing line, and although there are various freezing depths depending on the region, all of them are up to a certain depth from the ground surface, and in Hokkaido it can range from 5 to 80 cm. On slopes, there is a considerable amount of moisture in the soil, so the freezing depth is relatively shallow, said to be around 15 to 20 cm.

Due to this freezing of the soil, the soil up to the frozen depth of the soil layer is firmly attached to the anchor pin in a frozen state, and the anchor pin is raised to the ground surface due to expansion of the soil due to freezing, the so-called frost heaving phenomenon, and as I wrote at the beginning. This can lead to dangerous conditions and cause damage.

In order to prevent this, the main body of the anchor pin is covered with a tube made of polyvinyl chloride resin, so the phenomenon of frozen soil adhering takes place on this tube surface, and there is no phenomenon of frozen soil adhering to the main body, so the tube is responsible for the frost heaving effect. Therefore, it does not affect the pin body.

The anchor pin body remains driven in due to the strong frictional resistance of the ground into which it was driven, and is pulled up to the surface with frozen soil attached only to the tube.

In this case, referring to Figure 1, in the part 3 that is in close contact with the pin, the frictional resistance of the pin and the force of frozen soil adhesion or frost heaving force act in opposite directions, but these forces are stronger than the strength of the material of the tube. Therefore, it will either break at that part, or it will come out by scraping the surface of the pin.

This allows the anchor pin to remain safely in the ground.
It will not fall off even after many years, and the anchor pin can still serve its purpose.

Figure 5 shows the construction section on the slope, and Figure 6 shows the plane.

As described above, the present invention can largely prevent the phenomenon of anchor pins being stuck with frozen soil or slipping up or falling off due to frost heaving, which has not been solved for a long time.

In fact, the results of tests at 5 to 6 locations showed extremely effective results.

In addition, placing a cap over the head prevents water from accumulating in the gap between the pin and tube due to rainwater or other water seepage, and prevents frozen soil from adhering to the soil, tube, and pin when freezing occurs, or from frost heaving. This is to do so.

[Brief explanation of the drawing]

Figure 1 is a vertical cross-sectional view of the anchor pin, Figure 2 is the
- An enlarged X-ray cross-sectional view, Figure 3 is a vertical cross-sectional view of the state in use, Figure 4 is a plan view when used at the intersection of a legal frame, Figure 5 is a vertical cross-sectional view of an example of use, and Figure 6 is a vertical cross-sectional view of the usage state. FIG. 2 is a plan view of an example. A... Anchor pin, 1... Anchor pin body, 2... Polyvinyl chloride resin tube, 3
...The part that is in close contact with the pin, 4...Cap, 7...
...Steel flakes.

Claims (1)

[Claims for Utility Model Registration] 1. An anchor pin characterized by covering the pin body with a heat-shrinkable polyvinyl chloride resin tube, bringing the lower end of the tube into close contact with the pin, and covering the head with a cap. . 2. The anchor pin according to claim 1 of the utility model registration claim, in which thin steel pieces 7 are adhered to the back and front sides of the head of the cap.