JPH0444504A - Frost heave prevention method - Google Patents

Abstract

PURPOSE:To prevent ground surface or road surface from damage caused by frost heave by heating up the earth within the frost line from the inside thereof to keep heat and warmth, and preventing water in the ground from freezing. CONSTITUTION:Heating elements 2 and a temperature sensor 3 are installed in the earth within the frost line 7 in the ground 1. When the temperature in the ground falls to 0 deg.C in the winter season, the temperature sensor 3 detects an underground temperature, an automatic control-panel is operated to heat up the heating elements 2, the ground is heated to keep heat and warmth, and the freezing of the underground water is prevented. According to the constitution, cracks on the road surface caused by frost heave can be prevented.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is applicable to the ground and road surfaces of roads, parking lots, railway tracks, tennis courts, farm fields, etc. in snowy areas, cold areas, high mountain areas, and coastal industrial areas. , or relates to a method for preventing frost heaving damage occurring under freezers and liquefied gas storage equipment.

[Conventional technology]

Traditionally, frost heave is a phenomenon commonly seen in cold regions.When the temperature drops below 0℃ in winter, the pore water in the soil near the ground surface begins to freeze, and the frozen surface gradually moves downward into the soil over time. At that time, depending on conditions such as soil quality and soil moisture, water may move to the frozen surface, or by freezing, an ice layer is formed horizontally on the ground surface, and water is absorbed from the unfrozen part to the frozen surface. Frost heave is a phenomenon in which the ground swells due to the freezing of water in the soil.

As a result, there is a risk that cracks may appear in the paved surfaces of roads, etc., or railway tracks may be lifted up, causing serious disasters. In particular, during the day, molten water seeps into cracks that occur on roads, etc., and at night, this water freezes and swells in volume, causing the cracks to grow larger and wider, and eventually tortoiseshell-shaped cracks spread out on the road surface. becomes corrupted.

In addition, in recent years, with advances in road snow removal technology, complete snow removal using snow removal equipment has become more common, so roads in snowy areas have almost no snow even in winter, reducing the insulation effect of snow and leaving the road surface constantly exposed to the cold outside air. Because there are
Heat is constantly being taken away from the road surface, and damage caused by frost heave has begun to be seen everywhere in snow-covered areas and high-altitude mountain areas.

In addition, the damage caused by this frost heave occurs in the spring when the frost pillars in the ground melt and a large amount of water is sucked up from below and accumulates underground, reducing the bearing capacity of the roadbed and roadbed, causing local ground subsidence and collapse. Occur.

Therefore, damage caused by frost heave is not limited to roads in snowy and cold regions, but also roads in high mountainous areas and coastal industrial areas, parking lots, railway tracks, airfield runways, port piers, tennis courts, and agricultural fields. Frost heaving damage was also seen on roads such as the foundations of refrigeration facilities and on the surface of wharves, and urgent countermeasures were needed.

To date, measures to prevent frost heaving that have been taken against this kind of damage include replacing the existing roofs at depths up to the freezing depth in the area with granular materials that are less likely to cause frost heave, and preventing frost heave underground or beneath the roadbed. Replacement methods that provide a suppression layer, multiple insulation materials between the subgrade and the subgrade to prevent heat from the subgrade from being transferred to the ground surface to prevent frost heave, and even the use of a grid-like high Covered with a molecular resin net, the roadbed material and the net work together to resist frost heaving, allowing frost heaving to occur uniformly, preventing local heave-up of the road surface, and preventing the formation of tortoiseshell-shaped cracks that occur on the road surface. Although attempts have been made to prevent frost heaving, it has not been possible to completely prevent frost heaving.

[Problem to be solved by the invention]

The present invention has been made in view of the above circumstances, and the heat in the earth is taken away from the earth's surface, the inside of the earth and the roadbed are cooled and frozen, the frost heave phenomenon occurs, and the ground and road surfaces swell.
In particular, in the case of roads after snow removal, cracks appear and gradually expand, creating tortoiseshell-shaped cracks on the road surface, which can eventually lead to damage to the ground and road surfaces due to frost heave.
The objective is to provide a frost heaving prevention method that can create ground and road surfaces that are safe, easy to maintain, and durable.

[Means to solve the problem]

The present invention is a method for preventing frost heaving to achieve the above-mentioned object, by warming the soil within the freezing depth from the inside to store heat and prevent moisture in the ground from freezing and causing the above-mentioned swelling to occur on the ground surface. It is a method to prevent frost heaving damage, and it is also a method to prevent frost heave damage that occurs on the road surface due to the swelling of the subgrade by heating the subgrade from the inside and storing heat to prevent moisture in the subgrade from freezing. Furthermore, after the snow is removed by a snow removal device, the soil below the frozen depth of the ground surface or road surface is heated from within to store heat and retain heat, preventing moisture in the ground from freezing and causing the above-mentioned swell to form on the ground or road surface. This is a method to prevent frost heaving damage.

[Effect]

The method for preventing frost heaving of the present invention is that the outside air is O”C for a long period of time.
When the earth gets colder than that, when cold wind blows, or when there is low-temperature equipment on the earth's surface, the heat underground continues to be removed from the earth's surface, until it cools down to the depths of the earth, reaching 0°C. At this time, heating equipment installed underground warms the underground and stores heat, keeping it at a temperature of 0°C or higher to prevent frost heaving damage such as swelling of the ground surface due to freezing and expansion of moisture in the ground. can be prevented.

In this case, when the underground temperature rises to a predetermined temperature in consideration of economic efficiency and energy saving, the operation of the facility is stopped by the function of the temperature sensor and the automatic operation panel, and the underground temperature is lowered to 0℃ or higher. Maintaining a constant temperature prevents underground water from freezing and prevents the ground surface from rising due to frost heaving.

Additionally, if the outside air cools to below 0℃ or cold wind blows for a long time, the heat inside the subgrade will continue to be removed from the road surface, and the temperature inside the subgrade will eventually reach t'LO℃. The subgrade is heated by heating equipment installed in the roadbed, stores heat, and maintains the subgrade at a temperature of 0°C or higher.
Frost heaving damage such as swelling and cracking of the road surface due to freezing and expansion of moisture in the roadbed can be prevented.

In addition, if the outside air cools below 0 degrees Celsius or cold wind blows on the ground or road surface after snow has been removed by a snow removal device, the heat underground will continue to be taken away from the ground surface and will eventually cool down to the inside of the ground. The temperature reaches 0℃, but at this time, heating equipment installed underground warms the underground and stores heat.
By keeping it at a temperature of 0°C or higher, it is possible to prevent frost heaving damage such as swelling of the ground or road surface due to freezing and expansion of moisture in the ground.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

(First Embodiment) FIG. 1 is a schematic cross-sectional view showing a first embodiment of the present invention, in which a heating element 2 and a temperature sensor 3 are installed inside the soil above the freezing depth line 7 of the underground 1. In the first embodiment configured in this way, the underground temperature is 0°C in winter.
When the temperature drops to below , the temperature sensor 3 detects the underground temperature, and an automatic operation panel (not shown) operates to cause the heating element 2 to generate heat to warm the underground, store heat, and prevent the moisture in the ground from freezing.

At that time, when the underground temperature rises to a predetermined temperature, for example 3 degrees Celsius, in consideration of economic efficiency and energy saving, the operation of the facility is stopped by the function of the temperature sensor and automatic operation panel.
The temperature underground 1 is maintained at a constant temperature of 0°C or higher to prevent underground water from freezing and to prevent the ground surface from rising due to frost heaving.

In addition, the freezing depth of the ground is determined by soil quality, groundwater level, amount of solar radiation,
It changes depending on snowfall amount, wind speed, etc., but it also changes depending on the color of the road surface, type of pavement, topography, etc.

Note that the method for calculating the freezing depth differs depending on various cases, but for example, when the ground is made of -like soil quality, it can be calculated using the following formula.

Z: Freezing depth (an) F: Freezing index (accumulated cold temperature, °C/day) K: Average thermal conductivity when frozen and unfrozen (cafl/aI+・sec−”C) L: Latent heat of fusion (caρ /at?) λ: Correction coefficient The heating element 2 in this embodiment is, for example, heated by electric heat, but it is also possible to send underground water, heated hot water, or warm antifreeze using a heating tube, heating plate, or heat pipe through which a fluid passes. Alternatively, the underground 1 may be heated using deep or shallow geothermal heat, various types of waste heat, or the like as a heat source.

Furthermore, the installation depth of the heating element and temperature sensor may be determined by considering the depth of freezing in the area.

(Second Embodiment) FIG. 2 is a schematic sectional view showing a second embodiment of the present invention. In the figure, a road surface 4 is made of a pavement material such as asphalt or concrete, and a roadbed 5 made of granular material is provided below.
The lower surface of the roadbed 5 is in contact with the roadbed 6, and the heating element 2 and temperature sensor 3 are installed at the interface between the roadbed 5 and the roadbed 6 above the freezing depth line 7 or within the roadbed 6. .

In the second embodiment configured in this way, when the temperature of the roadbed 6 drops to 0°C in winter, the temperature sensor 3
An automatic operation panel (not shown) operates to cause the heating element 2 to generate heat, thereby warming the roadbed 6 and storing heat therein.

At this time, when the temperature of the subgrade 6 rises to a predetermined temperature in consideration of economic efficiency and energy saving, the operation of the facility is stopped by the action of the temperature sensor 3 and the automatic operation panel, and the temperature of the subgrade 6 is raised to 0°C or higher. This prevents moisture in the roadbed from freezing and prevents cracks in the road surface 4 due to frost heaving.Furthermore, in the spring, when frost pillars in the ground melt, a large amount of water accumulates underground, causing damage to the roadbed and roadbed support. By reducing the force, it is possible to prevent localized ground subsidence and cave-ins from occurring.

The heating element 2 in this embodiment is, for example, electrically heated, but it may also be installed using a heating tube, a heating plate, or a heat pipe through which a fluid passes, such as underground water, heated hot water, or warm antifreeze, and the installation location is preferably within the subgrade. However, it may be inside the roadbed or within the pavement.

Furthermore, the roadbed may be heated using deep or shallow geothermal heat, various types of waste heat, or the like as a heat source.

In addition, hot air is sent directly into the gaps in the roadbed to warm the roadbed.
Frost heaving prevention may be carried out.

(Third Embodiment) In the third embodiment of the present invention, the soil below the ground surface or road surface after snow removal by the snow removal device is removed above the freezing depth line 7 in the ground 1, as in the first embodiment. A heating element 2 and a temperature sensor 3 are installed inside the soil, and when the underground temperature drops to 0℃ in winter, the temperature sensor 3 detects the underground temperature, and an automatic operation panel (not shown) operates to turn the heating element 2 on. generates heat, warms the ground, stores heat, and prevents moisture in the ground from freezing.

At that time, when the underground temperature rises to a predetermined temperature considering economic efficiency and energy saving, the operation of the facility is stopped by the function of the temperature sensor and automatic operation panel, and the underground temperature is kept at a constant temperature of 0℃ or higher. This prevents underground water from freezing and prevents the ground or road surface from rising due to frost heaving after snow removal by snow removal equipment.

〔Effect of the invention〕

Since the present invention has the configuration as described above, it has the following effects.

In the frost heaving prevention method according to the present invention, when the underground temperature falls below a predetermined temperature, a heating element installed underground generates heat, effectively warming the underground, storing heat underground, and increasing the temperature underground. Since the temperature is maintained at a constant temperature of 0°C or higher, it is possible to prevent the moisture in the ground from freezing and prevent the rise of the ground surface due to frost heave.

In addition, when the temperature of the subgrade falls below a predetermined temperature, the heating elements installed in the subgrade generate heat, effectively warming the subgrade and storing heat within the subgrade, keeping the subgrade at a constant temperature of 0°C or higher. This prevents water in the roadbed from freezing and prevents cracks from forming on the road surface due to frost heaving. At this time, since the roadbed beneath the road surface is made up of a packed layer of granular materials and has many voids and low thermal conductivity, cooling from the ground surface is achieved by installing heating elements in the roadbed located at the bottom of the roadbed. The action is difficult to reach the subgrade, and the heat from the heating element is effectively stored, effectively warming and storing the subgrade against the cooling action received from the ground surface, and keeping the subgrade at a constant temperature of 0℃ or higher. Since the temperature is maintained, the roadbed can be prevented from freezing and cracks in the road surface due to frost heaving can be prevented.

In addition, when constructing roads in snowy areas, an artificial frost heaving suppression layer was placed under the roadbed. This prevents frost heaving by maintaining a constant temperature above 0℃, which eliminates the need for a frost heave suppression layer, reducing construction costs and construction time.
Since cracks do not occur on the road surface, the life of the facility can be extended.

In addition, the heating element installed underground generates heat during the winter, effectively warming the underground, storing heat underground, and keeping the underground at a constant temperature of 0°C or higher, which prevents moisture in the ground from freezing. It is possible to prevent accidents such as localized ground subsidence caused by a decline in the support capacity of the roadbed and roadbed caused by the melting of underground frost columns even in the spring.

Furthermore, when constructing buildings such as freezers, special reinforcing materials are required because installing insulation material underground weakens the supporting capacity of the ground. The heat generated by the subgrade prevents frost heaving by keeping the subgrade at a constant temperature of 0°C or higher, eliminating the need for insulation and reinforcing materials, reducing construction costs and construction time, and preventing cracks from forming on the floor. Therefore, it has many effects such as increased safety in maintaining and managing buildings.

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view showing the first embodiment of the present invention, and the second
The figure is a schematic sectional view showing a second embodiment of the invention. 1... Underground 2... Heating element 3... Temperature sensor 4... Road surface (paving body) 5... Roadbed
6... Roadbed 7... Freezing depth line.

Claims (3)

[Claims] (1) A frost heaving prevention method characterized by heating the soil within the freezing depth to store heat and keep it warm, thereby preventing moisture in the ground from freezing and causing damage to the ground surface due to swelling of the soil. . (2) A method for preventing frost heaving, which is characterized by heating the subgrade from the inside to store heat and keep it warm, thereby preventing water in the subgrade from freezing and causing damage to the road surface due to swelling of the subgrade. (3) After snow removal by a snow removal device, the soil below the frozen depth of the ground or road surface is warmed from within to store heat and keep the soil warm, preventing moisture in the ground from freezing and causing the soil to swell, causing the surface of the ground or road to swell. A frost heaving prevention method characterized by preventing frost heaving damage caused by.