Underground heat storage device

Abstract

To provide an underground heat storage device that suppresses frost heaving of the ground without using a waterproof sheet. [Solution] The underground heat storage device 2 comprises a pipe P buried below a protective sand layer 14, a pump 23 for circulating antifreeze, a boiler 24 for heating the antifreeze, and a controller 22 that outputs an instruction to the boiler 24 to heat the antifreeze depending on the measurement results of a water temperature sensor 21.

Description

[Technical field]

[0001] The present disclosure relates to soil thermal storage devices. [Background technology]

[0002] As described in Patent Document 1 below, a frost heave prevention method for preventing frost heave of the ground has been proposed. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 110323 / 1983 Summary of the Invention [Problem to be solved by the invention]

[0004] Patent Document 1 proposes a frost heave prevention method using a waterproof sheet to solve the problems associated with frost heave prevention methods such as the replacement method, the insulation method, the soil improvement method, the chemical method, and the waterproof method.

[0005] The present disclosure aims to suppress frost heave of the ground without using a waterproof sheet. [Means for solving the problem]

[0006] The present disclosure relates to an underground heat storage device for suppressing frost heave, comprising: a protective sand layer consisting solely of sand and dispersed in the plastic properties of sand so that no lifting force is generated even if a frozen area invades the soil of a freeze-suppressed area, the protective sand layer being provided to a depth of at least 100 mm; a pipe buried within the protective sand layer or below the protective sand layer; a pump for circulating antifreeze through the pipe; a water temperature sensor for measuring the temperature of the antifreeze circulating through the pipe; a heating unit for heating the antifreeze circulating through the pipe; and a controller that outputs an instruction to the heating unit to heat the antifreeze when the temperature of the antifreeze is expected to be lower than a set temperature or when the temperature of the antifreeze is lower than the set temperature as a result of measurement by the water temperature sensor. Effect of the Invention

[0007] According to the present disclosure, it is possible to suppress frost heave of the ground without using a waterproof sheet. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram for explaining this embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, the present embodiment will be described with reference to the accompanying drawings. In order to facilitate understanding of the description, the same components in each drawing are denoted by the same reference numerals as much as possible, and duplicated description will be omitted.

[0010] The underground heat storage device 2 according to this embodiment circulates heated antifreeze in a pipe P buried in a freeze-suppressed area. For example, in a region where frost heaving of soil is a problem in winter, if a building for housing livestock is constructed and handed over in spring, the temperature inside the building will rise after the handover because the livestock are housed there and the heat source is in operation, and frost heaving will no longer be a problem. Even in this case, it is necessary to suppress frost heaving before the handover. Various methods for preventing frost heaving have been proposed in the past, but since the underground heat storage device 2 according to this embodiment is intended to temporarily suppress frost heaving, it is required to be a device that realizes a simpler construction method.

[0011] In view of this background, the underground heat storage device 2 according to this embodiment heats the antifreeze liquid and circulates the heated antifreeze liquid in the pipe P buried in the freeze-suppressed area. For example, a known boiler 24 is used to heat the antifreeze liquid. The means for heating the antifreeze liquid is not limited to the boiler 24, and for example, an electric heating wire may be wound around the pipe P to heat the antifreeze liquid circulating in the pipe P. Also, a heat exchanger capable of heating the antifreeze liquid circulating in the pipe P may be provided. For example, a known pump 23 is used to circulate the antifreeze liquid. The antifreeze liquid heated by the boiler 24 is sent to the pipe P. The pipe P forms a circulation path and is arranged so as to suppress frost heaving in the freeze-suppressed area.

[0012] The antifreeze liquid heated by the boiler 24 is circulated during the period when frost heaving is a concern. As an example, the timing of heating and circulating the antifreeze liquid can be determined based on the day when the average daily temperature of the previous year is below zero degrees. Alternatively, the pump 23 may be driven to circulate the antifreeze liquid at all times, and the boiler 24 may be operated to heat the antifreeze liquid when the temperature of the antifreeze liquid is expected to be lower than the set temperature or when the temperature of the antifreeze liquid is lower than the set temperature. The temperature of the antifreeze liquid can be measured or estimated by various methods. For example, the temperature in the soil can be measured, and the temperature of the antifreeze liquid can be estimated from the measured temperature. For example, the temperature of the antifreeze liquid can be measured by the water temperature sensor 21 installed in the boiler 24. The water temperature sensor 21 may be installed on the circulation path of the pipe P, or may be installed in other manners as long as it can measure the temperature of the antifreeze liquid circulating in the pipe P. For example, the temperature of the antifreeze liquid can be estimated or measured by combining the temperature measurement result in the soil and the temperature measurement result in the water temperature sensor 21.

[0013] The underground heat storage device 2 according to this embodiment will be described further with reference to Fig. 1. Indoors, which is a freeze-suppressed area, there are provided, in order from the surface side, a dirt floor surface 10, a soil layer 12, a protective sand layer 14, and a ground layer 16. The dirt floor surface 10 is a surface layer of concrete. The soil layer 12 is a layer containing soil and stones.

[0014] The protective sand layer 14 is formed as a sand layer of about 200 mm on the ground layer 16, with the pipe P placed thereon. When heated antifreeze flows through the pipe P, the soil around the pipe P is prevented from freezing. As shown in the figure, the frozen area F reaches the ground surface outside the building and is in a frost heave state. The frozen area F does not reach the protective sand layer 14 around the pipe P, but reaches the protective sand layer 14 between the adjacent pipes P. The protective sand layer 14 is dispersed by the plastic properties of the sand so that even if the frozen area F penetrates, it does not generate a force that tries to lift the soil layer 12 and the earthen floor surface 10. In order to exhibit such dispersion performance, the protective sand layer 14 is preferably about 100 mm to 300 mm thick.

[0015] The buried position of the pipe P is about 650 mm from the floor surface 10. The buried position of the pipe P is appropriately set according to the freezing depth of the installation area. For example, in an area where the standard freezing depth is 1200 mm, the freezing depth is set to 1300 mm, taking into consideration years with abnormal weather, and the buried position of the pipe P is set at an intermediate depth of 650 mm. If the pipe P is buried close to the ground surface, heat will be dissipated from the floor surface 10, causing the heated layer to become thin, so it is preferable to place the pipe P at a position according to the freezing depth.

[0016] As described above, the underground heat storage device 2 according to this embodiment heats the antifreeze liquid and circulates the heated antifreeze liquid through the pipe P buried in the freeze-suppressed area.

[0017] In the underground heat storage device 2 according to this embodiment, antifreeze liquid is circulated before the timing at which freezing of the freeze-inhibited region starts.

[0018] In the underground heat storage device 2 according to this embodiment, the timing for starting freezing is determined from past temperature information in the freezing-suppressed region.

[0019] In the underground heat storage device 2 according to this embodiment, heating is performed when the temperature of the antifreeze liquid is expected to become lower than the set temperature or when the temperature of the antifreeze liquid becomes lower than the set temperature.

[0020] In the underground heat storage device 2 according to this embodiment, a protective sand layer 14 is provided in the soil of the freeze-suppressed region, and a pipe is buried in the protective sand layer 14 or below the protective sand layer 14 .

[0021] In the underground heat storage device 2 according to this embodiment, the protective sand layer 14 is provided to have a depth of at least 100 mm.

[0022] In the underground heat storage device 2 according to this embodiment, a pipe is buried in the lower end of the protective sand layer 14.

[0023] The underground heat storage device 2 according to this embodiment is an underground heat storage device for suppressing frost heave, A protective sand layer 14, which is made of sand only and has a depth of at least 100 mm, is dispersed in a plastic manner so that a lifting force is not generated even if a frozen area penetrates into the soil of the freeze-suppressed area; A pipe P buried in the protective sand layer 14 or below the protective sand layer 14; A pump 23 for circulating antifreeze through the pipe P; A water temperature sensor 21 for measuring the temperature of the antifreeze circulating through the pipe P; A boiler 24 as a heating unit for heating the antifreeze liquid circulating through the pipe P; The system is also equipped with a controller 22 that outputs an instruction to a boiler 24 as a heating unit to heat the antifreeze when the measurement result of the water temperature sensor 21 indicates that the temperature of the antifreeze is expected to be lower than the set temperature or when the temperature of the antifreeze is lower than the set temperature.

[0024] The present embodiment has been described above with reference to specific examples. However, the present disclosure is not limited to these specific examples. Any design modifications made by a person skilled in the art to these specific examples are also included within the scope of the present disclosure as long as they have the features of the present disclosure. The elements of each of the above-mentioned specific examples and their arrangements, conditions, shapes, etc. are not limited to those exemplified and can be changed as appropriate. The combination of each of the elements of each of the above-mentioned specific examples can be changed as appropriate as long as no technical contradiction occurs. [Explanation of symbols]

[0025] 2: Underground heat storage device P: Pipe F: Frozen area 10:Doma surface 12: Soil layer 14: Protective sand layer 16: Ground layer 21: Water temperature sensor 22: Controller 23: Pump 24: Boiler

Claims

1. A soil heat storage device for suppressing frost heave, a protective sand layer, which is made of sand only and is dispersed in a plastic manner so that a lifting force is not generated even if a frozen area penetrates into the soil of the freeze-suppressed area, and which is provided to a depth of at least 100 mm; A pipe buried in the protective sand layer or below the protective sand layer; a pump for circulating antifreeze through the pipe; a water temperature sensor for measuring the temperature of the antifreeze circulating through the pipe; A heating unit for heating the antifreeze liquid circulating through the pipe; and a controller that outputs an instruction to the heating section to heat the antifreeze liquid when the measurement result of the water temperature sensor indicates that the temperature of the antifreeze liquid will be lower than the set temperature or when the temperature of the antifreeze liquid has fallen below the set temperature.

2. The underground heat storage device according to claim 1, The pipe is buried at the lower end of the protective sand layer.

Images