JPS6010017A - Freezing damage preventive pile - Google Patents

Abstract

PURPOSE:To prevent the freezing damage to a pile by a method in which a covering part wish a bellows-shaped expandible portion, having a length longer than the thickness of an active layer or a seasonal freezing layer, is fitted on the pile, and a fluid substance is packed into the space formed by the pile and the covering part. CONSTITUTION:When an active layer 6 is frozen in the winter season, sand slurry 8 is also frozen to adhere to the surface of the convering part 11 of a pile 10. As the active layer 6 upheaves by freezing, the covering part 11 extends correspondigly along the pile 1 to form an expanded portion 12 a below a fixer 15. A fluid substance 17 packed into the space between the pile 1 and the coverin part 11 is moved upwards and gathered into the expanded portion 12a. The frost heaving force of the active layer 6 is absorbed by the covering part 11 and the fluid substance 17 and prevented from its transmission to the pile 1. When the active layer 6 is thawed and settled in summer season, the covering part 11 is also lowered and restored to its original state.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to pile foundations among the foundations for structures used in cold regions, and more specifically to piles for preventing frost damage.

When constructing pipeline frames and other structures in cold regions such as permafrost or seasonally frozen land,
Freezing of active layer and seasonal frozen layer? It is essential to protect structures from frost damage such as frost heave and thawing. For this reason, various countermeasures 1-method are used, the most common of which is pile foundations.

Here, permafrost areas include, for example, Alaska, Canada,
This refers to areas such as Siberia where there is a geological layer that is frozen throughout the year regardless of the season (hereinafter referred to as the F-frost layer), and the annual average temperature is below 0°C. The active layer refers to the layer from the ground surface to the permafrost layer, which is greatly affected by annual temperature changes, freezing and heaving in the winter, and thawing and sinking in the summer. Seasonal frozen soil is an area where there is no permafrost and the average temperature is below 0°C, and in winter it is 714°C.
It refers to a stratum that is solid and melts during the summer. In addition, in the above explanation, the seasonal frozen layer may be included in the active layer.

By the way, pile foundations in cold regions are deeply rooted in the Mizuku stock, and due to the high luminance between the permafrost and the pile surface,
This is intended to counteract the superstructure's own weight, ice build-up, and negative friction.
It is necessary to ensure the strength of the frozen bond between the permafrost and the piles, and to ensure that the piles have a sufficient depth of penetration into the permafrost. However, the permafrost layer does not necessarily have uniform properties, and the freezing strength varies greatly depending on the supernatant and temperature. Even if it is installed, the structure often suffers from frost damage, and the penetration length must be determined based on a design that takes into account the safety factor, which poses a major problem in terms of workability and economy. Because of these preconditions, several methods have been considered to reduce the frost heave that acts on pile foundations as a countermeasure. Figures 1 to 6 show permafrost. Figure 1 shows the thermal pile method, Figure 2 shows the frost heaving prevention pile method, and Figure 6 shows the frost heave prevention pile method, which is a conventional method for pile foundations in regions and seasonally frozen land zones. This is a pile method that increases the strength of waste.

Figure 1 is a vertical cross-sectional view showing an example of a thermal pile system, where 1 is a body made of steel pipe piles, concrete piles, etc., 2 is a corrugation provided on the outer periphery of the pile body 1 due to the freezing strength of 1 carcass, and the large size. Attach, 3
is a heat pipe inserted into the pile body 1, and 4 is a radiator. 5 is a permafrost layer, 6 is an active layer, and the pile body 1 is embedded in an excavated hole 7 provided in the active layer 6 and the permafrost layer 5, and is backfilled with an ice slurry 8. In addition, H indicates the rooting length of the pile body 1, and h indicates the thickness of the active layer 6.

When using this type of thermal pile system, the permafrost temperature of the joists is kept at a temperature of ±5°C during the winter using heat vibro.
By forcibly cooling the door and storing cold energy, the thickness of the active layer (h) decreases due to freezing and thawing.
This is intended to increase the ability to prevent frost heaving. Furthermore, this thermal pile can prevent the permafrost on the circumferential surface of the pile body 1 from melting due to heat input from the summer ζ double part structure. In other words, according to the thermal pile method, as the permafrost around the pile thaws and sinks, the piles experience oxidative friction, and in the winter, this thawing area freezes and causes excess frost heave on the pile. The power is tl! It is possible to prevent lI from falling.

However, the thermal pile is active layer 6! +
Although it is possible to make the + layer thinner, it is not possible to significantly reduce the freezing upper edge and negative friction, and it is still difficult to prevent frost damage of 1'1q structures to 1. For example, in the winter of the first year of practical use, due to a drop in the deep ground temperature, the amount of frost heave increases compared to when thermal piles are not used, and a large cIK 7i'f frost heave may occur. Furthermore, it is thought that the decrease in the temperature of the active layer also tends to increase the number of ice-heavy edges after the second line. In the conventional usage example, the penetration length of the thermal pile into the Mizuku soil is considerably long to prevent frost damage.
E-zen has existed in the past, and there are problems in terms of ease of construction and ease of construction.

A frost heave prevention pile is one in which a material is filled between the active layer and the surrounding surface of the pile to cut the distance τJ' MX between the pile and the frozen soil. A casing 9 is arranged concentrically with the pile body 1 on the outside of the pile body 1 to form a double front system.
The space between the casing 9 and the casing 9 is filled with a mixture 10 of oil and wax with high concentration, and the outer periphery of the casing 9 is not backfilled with sand slurry 8, so that the frozen heave blade can be separated. . In addition, 9α is 7 runs provided at the lower end of the casing, and No. 211 (bJ) is a material containing a mixture of oil and wax. It is a used item.

This type of frost heaving prevention pile method involves filling or backfilling the surrounding surface of the pile with a mixture of oil, wax, etc.

However, if machines and equipment are required for this purpose, it is not satisfactory either in terms of θ) or in terms of workability. The resulting mixture of oil, wax, etc. has enough fluidity to be pounded on site, so the backfill material is dispersed into the surrounding ground during the summer, making it difficult to refill. In addition, in the double front method, the casing will lift and sink as the active layer τ unfreezes. This may have an adverse effect on the superstructure.

Figure 6 shows a pile system with increased freezing strength, in which notches and corrugations 2 are provided at the part of the pile body 1 that penetrates into the permafrost 5, thereby creating a gap between the permafrost 5 and the pile body 1. The freezing strength of the active layer 6 is increased to counteract the freezing upper blade of the active layer 6.

In this method, the properties of the permafrost at the root of the pile body 1 are not necessarily uniform, and the freezing strength (2 variations occur).
Since the shape and spacing of the notches and corrugations change the frosting upper edge, in order to obtain a large frosting strength, it is necessary to manufacture and process the ends with a high degree of precision, such as processing the ends into irregularly shaped steel bars. There is a problem.

The present invention was made to solve the conventional problems as described above. The objective is to completely prevent frost damage to the upper structure by adding a member to the antibody.

In order to achieve the above object, the frost damage prevention pile according to the present invention is a pile of a type that reduces the freezing upper blade and negative friction that act on the pile in cold regions, and has a bellows-like extensible portion at least in part. A covering member having a thickness equal to or greater than the thickness of the active layer or seasonal frozen layer is fitted onto the antibody, and its lower end is below the bottom of the active layer or seasonal frozen layer, preferably at the same position as the bottom. (In addition, the upper end portions are placed as high as possible above the ground surface and fixed to the antibodies respectively, and a space formed by the antibody and the covering member (characterized in that it is filled with a bifluid substance) is formed. The present invention will be explained below using the drawings.

FIG. 4 is a longitudinal sectional view of an embodiment of the present invention. So classy.

Are the same parts as in Figures 1 to 6 the same numbers? r ('J
't,.

The explanation will be omitted. 11 is a bellows-shaped 1■ extension part 12 in the middle
It is a covering member with cylindrical parts 13 and 14 provided above and below it, with the upper cylindrical part 16 located as high as possible above the ground surface, and the lower cylindrical part 14 located between the active layer 6 and the permafrost layer 5. It is watertightly fixed to the pile body 1 by fixing members 15 and 16 near or below the boundary.

Reference numeral 17 denotes a fluid substance filled in the space between the pile body 1 and the covering member 11.

The 61st column (α) is an enlarged view of the main part of the extensible part 12 of the covering member 11, in an unloaded state (the ratio of XYZ and Xz in 2 is
The shape of the extensible part 12 may be any shape such as an S group curve, an arc, etc. It can also be machined in a straight line as shown in the figure.The smallest diameter part of the hoof covering member 11 (
Although it is desirable that X-Z) be brought into contact with the pile body 1 in order to reduce the amount of filling of the fluid substance 17, this is not particularly limited and they may be separated.

Although the covering member 11 used in the present invention varies depending on the region C, in general, 1) it does not cause brittle fracture from normal temperature to about -50°C, and 2) it is recoverable and the displacement is caused by freezing and frost heaving of the active layer 6. All conditions are that the amount (h, -h) is higher than the amount (h, -h), and that it does not deteriorate or spoil due to fluid substances.Assuming that these conditions are satisfied, the representative example is iP1+.
= Show.

In addition, the fluid substance 17 is regional (although there is some variation from 2).
In general, the material must: 1) exhibit fluid behavior from room temperature to a low temperature of about -50°C, and 2) be a material that does not deteriorate or corrode the pile body 1 and covering part (A11), and these conditions are met. - Typical examples 'f' are shown in Table 2.

Table 2 The frost damage prevention piles constructed as above are installed using the construction method described by Tsuneji Nishi (2). '), then recite that ill'j hole 7
Pile 1 () is erected in Jif, -11-.

Here, h is the thickness of the active layer 6, and H is the length of the pile penetration into the permanent soil layer't, l.

(2) If the strength of the permafrost layer 5 is extremely small or if it is rooted in unfrozen soil, only the active fdJ layer 6'< +
Ji! After drilling the piles 10 into the excavated holes 7, they are driven into permafrost or unfrozen soil using a pile driver, and finally .

Next, the action of the frost damage prevention pile according to the present invention installed as described above will be explained with reference to FIGS. 4 and 5. 1jlj drilling hole 7, where the prevention fj'1;10 was drilled into the active layer 6 and permafrost layer 5.
This figure shows the condition installed in the summer and the condition in the summer.

When the active layer 6 freezes in winter, the sand slurry 8 also freezes, causing the surface of the covering member 11 of the pile 10 to freeze. On the other hand, between the pile body 1 and the covering member 11, Since the flowing material 17 is filled, the sliding resistance between the two is small. Therefore, when the active layer 6 freezes up, the covering part 11 follows suit, as shown in Figure 5 (2). It is pulled up and expanded along the pile body 1. However, the upper and lower cylindrical parts 13 and 14
is fixed to the pile body 1, so it is fixed by the extended extensible part 12? The expansion part 12 (Z) is formed at 1 of 115.

With the expansion of the wave 1 part 11, the pile body 1 and the enemy i 1J
+411 (: The filled fluid substance 17 is pushed upward and collects in the expansion part 12α formed in the second part b
o In this way, the active layer 6 extends to the pile body 1.
- The force is absorbed by the object member 11 and the fluid substance 17 and is not transmitted to the pile body 1 at all. In addition, the active layer 6 fluctuates widely depending on the region, and a large amount of fluid material was deposited on the expansion part 12 (1), so the expansion part 12a broke 4W, L, and the flowing crop W1.
For JJ) tables where there is a risk of leakage, a tank 18 may be provided and communicated with the expansion part 12a to release the fluid substance 17 that has collected in the expansion part 12a.

When the active layer 6 melts and sinks in the summer, the covering member 11 also descends following this, returning to the state shown in FIG. 41 again.
In addition, the negative friction that occurs due to the melting and subsidence of the active layer B is absorbed by the fluid material J7 17, and the pile body 1
FIG. 7 is a longitudinal sectional view of another embodiment of the present invention, in which the same parts as in FIG. 4 are given the same reference numerals.
89 Ming road through the mountains. In this embodiment, the covering member 21 is constructed by separately purchasing the cylindrical part 22, the lower extensible part 26, and the lower extensible part 24, and the upper part is re-extensible lR1.
-1 part 23 is placed on the ground surface, and the lower extensible part 24
are fixed to the fixed members 15, 16+n and the pile body 1, respectively, near or below the boundary between the active layer 6 and the permafrost layer 5. It is filled with a sexual substance 17. Furthermore, the AK4+ (substance) constituting the covering member 21 and the fluid substance 17, the combination thereof, and the installation nail method are the same as those described in the embodiment shown in FIG.

Figure 7 shows the state in which the frost damage protection 1E pile 10 (Z) is installed in the excavation hole Z and the state in summer. 2 Following this, the cylindrical part 22 and the lower extendable part 24 rise,
The lower expandable portion 24 is expanded.

As a result, the lower stretchable portion 23 is deformed to form an expanded portion 23α, which accommodates the fluid substance 17 that has risen due to the extension C2 of the lower stretchable portion 24. Other functions are almost the same as those in the embodiments shown in FIGS. 4 and 5.

? Figure tfJ9J is a vertical cross section showing the main parts of the second embodiment of the present invention.This embodiment shows the main parts of the serpentine (1ν-shaped extensible part 12) of the covering member 11 and the pile body. A ring 25 is interposed between C 1 and C 2, respectively, which can prevent deformation and damage of the extensible part 12 due to the pressure of the active layer B through the sand slurry 8 (il). .

(Figure b1 shows the relationship between the pile body 1, the covering member 11, and the ring 25 when the live layer 6 is frozen and heaved. Among these, the ring 25 is attached to the small diameter part of the extensible part 12. It may be interposed on the outer periphery, or riJI11] condensed part 12
The buried part 12 is good.

The shape of the expandable part of the covering member is shown in each of the above embodiments (two), but the present invention is not limited to these.
For example, as shown in Figure 10 (al to (d+), various shapes can be used. Experimental results for the case where it is used on piles (I will explain it in two parts. In the fourth experiment, a fire was used as shown in Fig. 11. This device was set up on the base 31)
A reaction frame 36 is bridged between the l/-mu 32.32, and an earthen tank 35 is installed on the base 61, surrounded by a heat insulating filter 4 with a thickness of 100 mm, and filled with earth 36 inside. ,
By erecting this ±36 medium ζ2 model pile 7,
[Experimental Example] (1) A load cell 6 is interposed between the soil tank 65 and the reaction frame 33, and a displacement meter 69 is installed to determine the surface displacement of ±36 within the soil tank 65. ) Steel pipe pile (conventional outside diameter: 64M, length: 400mm, embedment depth: 250mm)
m[[l (2> Freeze damage prevention pile (corresponding to the example in Figure 4) (
α) Antibody dimensions Outer diameter: 27.5mm, length: 400mm, embedding length: 25
Zero-valent (b) Material and dimensions of coating member Low-density polyethylene Thickness: 1.5 mm, Mountain pitch: 9. Omm.

Difference between peak and valley: 6. Oym, covering length: 300mmfC1 style! 1ψ material - isoparaffin (013~C+s) A conventional steel pipe pile as described above and a damage prevention pile of the present invention (1) were installed in the experimental apparatus shown in Fig. 11 (IJ1), respectively.
After placing the experimental device in the freezer, it was started at room temperature, cooled at 0℃ for 11 hours, then changed to -40℃ after about 241 days, and the temperature was changed to about 48℃. Cooling was discontinued after continuing at IIJ1.
Figure 12C2 shows the results of determining the change over time in the amount of frost heaving of No. 36 using the displacement ruler 9, and Figure 13 shows the result of measuring the change in the frost heave over time using the load cell 68. show(
In the figure, A) is the conventional steel pipe pile, B) is the experimental result of the frost-proof IE pile of the present invention). (1) Although the amount of frost heave is almost the same between the two, the frost heave blade has a valley of 11 kaya (A+ is 3.5 A?) at -40℃.
/ cA, whereas the frost damage prevention pile CB+ according to the present invention was almost 0, confirming that it had a significantly lower freezing force.

In the above embodiments, the present invention was applied to steel pipe piles (1), but the present invention can also be applied to concrete piles, wooden piles (2), and in addition, conventional frost damage prevention (1): , stake (
For example, it can also be used in conjunction with Fig. 6 (- frost bending strength) W increased pile). The materials, shapes, dimensions, etc. of other parts are also limited to those in the above embodiments, and may be modified as appropriate without departing from the gist of the present invention.

As is clear from the above description, C2 and I'1 according to the present invention can bring about the following remarkable effects.

(1) Since the active layer against antibodies can be frozen to /IO, the groove proboscis can be sufficiently protected from frost damage in cold regions.

(2) Since it is possible to reduce the amount of frost heave acting on antibodies, the length of pile penetration can be significantly shortened. Furthermore, when considering implementation and maintenance, costs can be reduced significantly.

[Brief explanation of the drawing]

Figures 1 to 3 (s) show the conventional frost heaving blade reduction method, @i figure shows the thermal pile method, and figure 2 fal
, (/Jl is a frost heaving prevention pile system, and Figure 5 is a frost heaving strength increasing pile system. Figure 4 is a longitudinal IEIi view of the embodiment of the present invention, i: Fu Figure 5 is an explanatory diagram of its operation, and Figure 6 Figure (αl, (
b+ is an enlarged sectional view of the main part showing an example of the structure of the expandable part of the covering part used in the present invention, FIG. 7 is a longitudinal sectional view of another embodiment of the present invention, and FIG. 8 is an explanation of its operation. Figure 9f is a schematic diagram showing an example of the shape of the extensible part of the upright member, and Figure 11 is the present invention C1.
Fig. 12 is a conceptual diagram of a device for testing such frost damage prevention IP piles, and a diagram showing changes over time in the amount of frost heaving between conventional steel ear piles and frost damage prevention piles according to the present invention, i(!, Figure 13 is a diagram showing the change over time of the frost-heaving blade. 1: Pile body, 5: Permafrost layer, 6: Active layer, 8: Sand slurry, 10, 10a: Freeze damage prevention pile, 11. 21: Covering member, 12, 23, 24: Town (iJ contraction r) 1≦, 15.16
: Solid member. Representative Patent Attorney Sanro Kimura Figure 7 Figure 8 Figure 9 (a) (1)) Figure 10 (a) (b) (c) (d)

Claims (1)

[Claims] Freezing heave force and ice heaving force acting on piles in cold regions
In a pile of a type that reduces traction, a covering member having a bellows-like extensible part at least in part and having a length equal to or greater than the thickness of the active layer or seasonally frozen layer is fitted onto the antibody, and the lower end of the covering member is fitted onto the antibody. The part is fixed to the antibody near or below the bottom of the active layer or the seasonal frozen layer, and the upper part is fixed to the antibody above the ground surface, and flows into the space formed by the antibody and the covering member. A frost damage prevention pile characterized by being completely filled with a chemical substance,