JP5042786B2 - Freezing device, frozen soil calculation system, freezing method and program - Google Patents

Description

In the artificial ground freezing method for freezing the ground for water stoppage in the case of construction such as underground cutting expansion work and underground joints of shield machine, the present invention can shorten the frozen soil creation period, The present invention also relates to a freezing apparatus, a frozen soil calculation system, a freezing method, and a program capable of reducing the frost heaving phenomenon and freezing expansion pressure due to the growth of frozen soil more than necessary.

The artificial ground freezing method can improve the ground more homogeneously and reliably than the ground improvement by chemical injection, and it is difficult to improve the ground from the ground and the high ground pressure is difficult for deep construction. In many cases, the artificial ground freezing method is adopted for the reliable ground improvement. According to the artificial ground freezing method, it is predicted that it will return to the original ground by thawing the frozen soil after the completion of construction, so that the burden on the environment is small, and it will be applied to various fields in the future.

FIG. 10 is a diagram showing the construction of the underground joint portion of the shield machine. The shield tunnels 307a and 307b are constructed by the shield machine 301a and the shield machine 301b, and in order to join the constructed shield tunnels, the frozen pipes 303a and 303b are provided from the shield tunnels, and the frozen soil 305a and 305b is constructed. By forming the frozen soil 305a, 305b, the ground can be reinforced and the water can be stopped, and the construction can be performed safely and reliably.

In such an artificial ground freezing method, a refrigerant is poured into an embedded freezing pipe to cool the surrounding ground, thereby generating and growing frozen soil. As the refrigerant, brine (antifreeze) is usually used, and it is cooled to about -25 ° C to -35 ° C. However, if the brine having such a temperature is circulated to form a frozen soil having a required thickness, there is a problem that depending on the construction situation, it takes 2-3 months to form the frozen soil and the construction period becomes longer.

On the other hand, the formation rate of frozen soil greatly depends on the temperature of brine circulating in the freezing pipe. For this reason, in order to shorten a construction period, there exists the method of forming frozen soil using the liquefied gas which is a refrigerant | coolant of lower temperature (patent document 1).
JP 2007-169967 A

However, the freezing apparatus according to Patent Document 1 can increase the formation speed of frozen soil by reducing the circulating refrigerant temperature and shorten the construction period. However, in order to consider only the frozen soil thickness, the refrigerant temperature should be lowered. Only the effect of increasing the formation speed of frozen soil can be obtained. Moreover, it is necessary to drastically change the conventional cooling equipment, and there is a problem that a refrigerant cost is required in a large-scale construction. In addition, since the growth of frozen soil proceeds after the set thickness of frozen soil, unnecessary energy is consumed, and the frost heaving phenomenon and the freezing expansion pressure increase as the frozen soil thickness increases.

Even if the supply of refrigerant is stopped or the refrigerant temperature is increased after the freezing area is frozen, the setting of the freezing area only takes into account the frozen earth thickness assuming a constant frozen earth temperature. The relationship between temperature and the strength of frozen soil is not taken into account at all, and unnecessary frozen soil is formed from the viewpoint of frozen soil strength, so that there is a problem that frozen soil is not effectively used in terms of construction period and cost. is there.

The present invention has been made in view of such a problem. Rather than simply determining the formation of frozen soil based on the thickness of the frozen soil, the frozen soil strength per unit area based on the frozen soil temperature (hereinafter simply referred to as “frozen soil strength”). By taking into account, it is possible to know the minimum period of frozen soil formation necessary for the use of frozen soil according to the frozen soil temperature at each point in time, so that the frozen soil formation period can be shortened and the brine temperature is controlled Accordingly, it is an object of the present invention to provide a freezing apparatus, a frozen soil calculation system, a freezing method, and the like that can reduce the frost heaving phenomenon and freezing expansion pressure due to the growth of frozen soil more than necessary.

In order to achieve the above-described object, the first invention is a cooling system in which a freezing pipe embedded in the ground, a plurality of thermometers embedded in the periphery of the freezing pipe, and a brine cooling for flowing a brine of a predetermined temperature through the freezing pipe. Using the circulation device, the ground temperature data measured by the thermometer, and the brine temperature data measured by the brine cooling circulation device, the optimum brine temperature is calculated from the relationship between the frozen soil temperature and the frozen soil strength, And a control device that controls the brine cooling and circulating device so as to circulate the brine at the optimum brine temperature to the freezing tube.

The control device includes ground temperature data measured by the thermometer, frozen soil thickness calculating means for calculating a frozen soil thickness from an installation position of the thermometer, brine temperature data measured by the brine cooling circulation device, The frozen soil temperature calculating means for calculating the frozen soil temperature from the frozen soil thickness, the frozen soil strength calculating means for calculating the frozen soil strength from the frozen soil temperature, and the maximum frozen soil stress generated in the frozen soil when the frozen soil is used. Frozen soil maximum stress calculation means calculated from thickness, frozen soil stress comparison means for comparing the frozen soil strength with the frozen soil maximum stress, and when the frozen soil strength is greater than the frozen soil maximum stress, it is optimal from the frozen soil maximum stress. Optimum frozen soil temperature calculating means for calculating the frozen soil temperature, and optimum brine temperature calculating means for calculating the optimum brine temperature from the optimum frozen soil temperature and the frozen soil thickness may be provided. .

The finite element method further comprises a heat conduction osmotic flow coupled analysis device capable of calculating the predicted frozen soil thickness by analyzing the heat conduction analysis and groundwater seepage flow from the brine temperature and the freezing pipe installation position. The heat conduction osmotic flow coupled analysis device calculates a frozen ground thickness after a lapse of a delay time from a delay time until the brine temperature actually changes after controlling the brine temperature, and calculates a predicted frozen soil thickness after the lapse of the delay time. The control device may further include a maximum stress correction unit that corrects the maximum frozen soil stress from the frozen soil thickness after the delay time has elapsed.

According to the first invention, by calculating the frozen soil strength from the frozen soil temperature using the relationship between the frozen soil temperature and the frozen soil strength, it is possible to know the minimum necessary frozen soil thickness corresponding to the frozen soil temperature at each time point. For this reason, the use of frozen soil can be started without growing the frozen soil thickness more than necessary, and the construction period can be greatly shortened. In addition, as the frozen soil thickness increases, the necessary frozen soil temperature is calculated back to calculate the optimum brine temperature according to the frozen soil thickness, thus reducing unnecessary energy consumption and reducing frost heave and freezing expansion pressure. be able to. In addition, if the delay time of the brine temperature change is taken into consideration, a more appropriate brine temperature can be set, and a freezing device excellent in the utilization efficiency of frozen soil can be provided.

According to the second aspect of the present invention, the heat conduction analysis and the groundwater seepage flow are simultaneously analyzed from the brine temperature and the freezing pipe installation position by the finite element method, so that the change in the frozen soil thickness and the frozen soil temperature with time can be calculated. The brine temperature for calculating the optimum brine temperature from the relationship between the frozen soil strength and the frozen soil temperature, using the conduction osmotic flow coupling analysis means, the frozen soil temperature calculated by the heat conduction osmotic flow coupling analysis means, and the brine temperature. A frozen soil calculation system characterized in that a control means and the optimum brine temperature are applied to the heat conduction osmotic flow coupling analysis means to calculate a change over time in the frozen soil thickness and the frozen soil temperature.

The brine temperature control means, the frozen soil strength calculation means for calculating the frozen soil strength from the frozen soil temperature calculated by the heat conduction osmotic flow coupled analysis means, and the maximum frozen soil stress generated in the frozen soil when the frozen soil is used, Frozen soil maximum stress calculating means for calculating from the frozen soil thickness, frozen soil stress comparing means for comparing the frozen soil strength and the frozen soil maximum stress, and when the frozen soil strength is greater than the frozen soil maximum stress, The optimum frozen soil temperature calculating means for calculating the optimum frozen soil temperature, and the optimum brine temperature calculating means for calculating the optimum brine temperature from the optimum frozen soil temperature and the frozen soil thickness may be provided.

From the delay time until the brine temperature actually changes after controlling the brine temperature, the frozen soil thickness calculating means for calculating the frozen soil thickness after the delay time elapses, and the frozen soil thickness after the delay time elapses from the frozen soil thickness Maximum stress correction means for correcting the maximum frozen soil stress may be further included.

According to the second invention, by calculating the frozen soil strength from the frozen soil temperature using the relationship between the frozen soil temperature and the frozen soil strength, it is possible to know the minimum required frozen soil thickness corresponding to the frozen soil temperature at each time point. it can. For this reason, it is possible to calculate the shortest start time of the frozen soil without growing the frozen soil thickness more than necessary. As the frozen soil thickness increases, the necessary frozen soil temperature is calculated back to calculate the optimal brine temperature according to the frozen soil thickness. A frozen soil calculation that can be reduced can be performed. Moreover, if the delay time of the brine temperature change is taken into consideration, a more appropriate brine temperature can be set, and a frozen soil calculation system excellent in utilization efficiency of frozen soil can be provided.

In a third aspect of the invention, a step of installing a freezing pipe and a thermometer, a step of circulating brine to the freezing pipe by a brine cooling circulation device, a ground temperature is measured by the thermometer, and the temperature of the brine is further increased. A step of measuring, a step of calculating an optimum brine temperature from the relationship between the frozen soil strength and the frozen soil temperature using the ground temperature and the brine temperature, and a step of circulating the brine of the optimum brine temperature to the freezing pipe; The freezing method characterized by comprising.

The step of calculating the optimum brine temperature includes the step of calculating the frozen soil thickness from the ground temperature data measured by the thermometer and the installation position of the thermometer, and the brine temperature data measured by the brine cooling and circulation device. Calculating the frozen soil temperature from the frozen soil thickness, calculating the frozen soil strength from the frozen soil temperature, and calculating the maximum stress of the frozen soil generated in the frozen soil when the frozen soil is used from the frozen soil thickness. Comparing the frozen soil strength with the maximum frozen soil stress, calculating the optimum frozen soil temperature from the frozen soil maximum stress when the frozen soil strength is greater than the maximum frozen soil stress, and the optimal A step of calculating an optimum brine temperature from the frozen soil temperature and the frozen soil thickness.

After calculating the optimum brine temperature, the brine temperature is controlled and then the actual brine temperature by analyzing the heat conduction analysis and groundwater seepage flow from the brine temperature and the freezing pipe installation position by the finite element method. Calculating a frozen soil thickness after the lapse of a delay time until the change of the time, correcting the frozen soil maximum stress from the frozen soil thickness after the lapse of the delay time, calculating a corrected frozen soil maximum stress, and the corrected frozen soil A step of calculating a corrected optimum frozen soil temperature from the maximum stress; a step of calculating a corrected optimum brine temperature from the corrected optimum frozen soil temperature and the frozen soil thickness after the lapse of the delay time; Instead of the optimum brine temperature, the post-correction optimum brine temperature brine may be circulated through the freezing tube.

According to the third invention, by calculating the frozen soil strength from the frozen soil temperature using the relationship between the frozen soil temperature and the frozen soil strength, it is possible to know the minimum required frozen soil thickness corresponding to the frozen soil temperature at each time point. Therefore, it is possible to know the start date of the frozen soil without growing the thickness of the frozen soil more than necessary, and the construction period can be greatly shortened. In addition, as the frozen soil thickness increases, the necessary frozen soil temperature is calculated back to calculate the optimum brine temperature according to the frozen soil thickness, thus reducing unnecessary energy consumption and reducing frost heave and freezing expansion pressure. A possible frozen soil calculation can be performed. Moreover, if the delay time of the brine temperature change is taken into consideration, a more appropriate brine temperature can be set, and a freezing method excellent in the utilization efficiency of frozen soil can be provided.

A fourth invention is a program for causing a computer to function as the control device described in the first invention. According to the fourth invention, it is possible to provide a program capable of implementing the first invention by a computer.

The fifth invention is a program for causing a computer to function as the frozen soil calculation system of the second invention. According to the fifth invention, a program capable of implementing the second invention by a computer can be provided.

According to the present invention, the formation of frozen soil based on the frozen soil temperature is considered in consideration of the frozen soil strength, rather than just determining the frozen soil thickness based on the thickness of the frozen soil. It is possible to know the time, and therefore, the frozen soil formation period can be shortened, and by controlling the brine temperature, it is possible to reduce the frost heaving phenomenon and freezing expansion pressure due to the growth of frozen soil more than necessary. A freezing device, a frozen soil calculation system, a freezing method, and the like can be provided.

Hereinafter, embodiments of the present invention will be described in detail. FIG. 1 is a schematic view showing a freezing apparatus 1 according to the present embodiment.

The freezing device 1 mainly includes a control device 3, a brine cooling / circulating device 5, a data collecting device 7, a display device 8, a freezing tube 13, a thermometer 17, and the like. The brine cooling and circulation device 5 includes a brine tank, a brine circulation pump, a brine cooler, and the like that are not illustrated, and each is connected by a pipe. That is, the brine cooling and circulation device 5 can adjust the temperature of the brine 31 and can circulate the brine 31 at a predetermined flow rate.

An inlet side pipe 9 and an outlet side pipe 11 are connected to the brine cooling circulation device 5, and the inlet side pipe 9 and the outlet side pipe 11 are connected to a freezing pipe 13. The inside of the freezing tube 13 has a double structure, and the brine 31 circulates in the inside. When the brine cooling / circulation device 5 flows the brine 31 to the inlet side pipe 9 (in the direction of arrow A in the figure), the brine 31 flows inside the double structure of the freezing tube 13.

When the brine 31 flows to the tip of the freezing tube 13, the flow direction is changed to pass the outside of the double structure inside the freezing tube 13 and return from the outlet side pipe 11 to the brine cooling circulation device 5 (in the direction of arrow B in the figure). Since the brine 31 is cooled to a predetermined temperature in the brine cooling circulation device 5 and then sent to the freezing pipe 13, when the brine 31 flows through the freezing pipe 13, the surrounding ground is frozen to form the frozen soil 21. .

A temperature measuring tube 15 is installed around the freezing tube 13, and a plurality of thermometers 17 are provided inside the temperature measuring tube 15. The thermometer 17 measures the temperature of the ground. That is, thermometers 17 are provided at predetermined intervals, and the ground temperature at each thermometer 17 installation position is measured by each thermometer 17. For this reason, the approximate temperature distribution of the ground around the freezing tube 13 can be known by the thermometer 17.

The brine cooling circulation device 5 and each thermometer 17 are connected to the data collection device 7. Accordingly, the data collection device 7 can collect the brine temperature data 25 from the brine cooling circulation device 5 and can collect the ground temperature data 23 from each thermometer 17. The data collection device 7 is also connected to the control device 3 and can transmit the collected data 27 to the control device 3. If the control device 3, the brine cooling circulation device 5, and each thermometer 17 are directly connected, the control device 3 can directly obtain the brine temperature data 25 and the ground temperature data 23. In this case, the data collection device 7 is unnecessary.

The control device 3 performs various calculations based on the obtained data 27 and a preset database, and calculates the optimum brine temperature. Details of the control device 3 will be described later. The control device 3 is connected to the brine cooling / circulation device 5 and transmits the optimum brine temperature data 29 to the brine cooling / circulation device 5 to change and control the brine temperature in the brine cooling / circulation device 5.

As will be described later, the control device 3 itself may have a display unit. However, the control device 3 is connected to the display device 8 separately, and the display device 8 is installed at a location away from the construction site, so that However, the situation of frozen soil 21 can be grasped. In FIG. 1, most of the freezing device 1 is provided on the ground surface 19, but the freezing device 1 can also be installed in an underground shaft or tunnel. In this case, if only the display device 8 is installed on the ground, the status of the frozen soil 21 can be grasped on the ground. The display device 8 displays, for example, frozen soil distribution, brine temperature, availability of frozen soil, and the like.

The brine 31 may be a general aqueous solution of calcium chloride, or an aqueous solution of an aqueous solution of a carboxylate such as formate or acetate that can be used at a lower temperature. In the present invention, the brine temperature to be initially circulated to the freezing pipe 13 is not specified, but in order to obtain the effect of shortening the construction period and to make the effect of the present invention more remarkable. The initial brine temperature is desirably about −50 ° C., which is lower than usual, and is preferably about −65 ° C. to −35 ° C. In this case, it is desirable to use an aqueous solution of carboxylate as the brine for safety, handling and cost.

Next, the control device 3 will be described. FIG. 2 is a hardware configuration diagram of a computer that implements the control device 3. In the control device 3, a control unit 33, a storage unit 35, a media input / output unit 37, a communication control unit 39, an input unit 41, a display unit 43, a peripheral device I / F unit 45, etc. are connected via a bus 47. .

The control unit 33 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like. The CPU calls a program stored in the storage unit 35, ROM, recording medium, or the like into a work memory area on the RAM, executes it, controls the drive of each device connected via the bus 47, and is performed by the control device 3. The processing described later (see FIGS. 4 and 5) is realized.

The ROM is a non-volatile memory and permanently holds a computer boot program, a program such as BIOS, data, and the like. The RAM is a volatile memory, and temporarily holds a program, data, and the like loaded from the storage unit 35, ROM, recording medium, and the like, and includes a work area used by the control unit 33 for performing various processes.

The storage unit 35 is an HDD (hard disk drive), and stores a program executed by the control unit 33, data necessary for program execution, an OS (operating system), and the like. As for the program, a control program corresponding to an OS (operating system) and an application program corresponding to processing described later are stored. Each of these program codes is read by the control unit 33 as necessary, transferred to the RAM, read by the CPU, and executed as various means.

The media input / output unit 37 (drive device) performs data input / output. For example, a floppy (registered trademark) disk drive, a CD drive (-ROM, -R, RW, etc.), a DVD drive (-ROM, -R, -RW etc.) and media input / output devices such as MO drives.

The communication control unit 39 has a communication control device, a communication port, and the like, is a communication interface that mediates communication between the computer and the network 49, and controls communication with other computers via the network 49.

The input unit 41 inputs data and includes, for example, a keyboard, a pointing device such as a mouse, and an input device such as a numeric keypad. An operation instruction, an operation instruction, data input, and the like can be performed on the computer via the input unit 41.

The display unit 43 includes a display device such as a CRT monitor and a liquid crystal panel, and a logic circuit (such as a video adapter) for realizing a video function of a computer in cooperation with the display device.

The peripheral device I / F (interface) unit 45 is a port for connecting a peripheral device to the computer, and the computer transmits and receives data to and from the peripheral device via the peripheral device I / F unit 45. The peripheral device I / F unit 45 is configured by USB, IEEE 1394, RS-232C, or the like, and usually has a plurality of peripheral devices I / F. The connection form with the peripheral device may be wired or wireless.

The bus 47 is a path that mediates transmission / reception of control signals, data signals, and the like between the devices.

Next, the configuration of the control device 3 will be described with reference to FIG. FIG. 3 is a schematic configuration diagram of the control device 3. The control device 3 includes frozen soil thickness calculating means 51, frozen soil temperature calculating means 53, frozen soil strength calculating means 55, frozen soil maximum stress calculating means 57, frozen soil stress comparing means 59, optimum frozen soil temperature calculating means 63, optimum brine temperature calculating means 65, A heat conduction osmotic flow coupling analysis means 67, a post-delayed frozen ground thickness calculation means 69, a maximum stress correction means 71, a brine temperature control means 73, and a ground information database 75 are provided.

The frozen soil thickness calculating means 51 receives the ground temperature data 23 from the thermometer 17 and calculates the frozen soil thickness from the calculated ground temperature distribution and the positional relationship between the freezing pipes 13. For example, if the boundary between the frozen soil 21 and the non-frozen ground is 0 ° C., the 0 ° C. position is calculated from the temperature distribution of the ground, and the thickness from the 0 ° C. position to the frozen pipe 13 position is assumed to be the frozen soil 21. Calculate (distance).

The frozen soil temperature calculating means 53 obtains the ground temperature distribution based on the ground temperature data 23 received from the thermometer 15, and the range of the frozen soil thickness calculated by the frozen soil thickness calculating means 51 from the ground temperature distribution and the arrangement of the freezing pipes 13. The average frozen soil temperature (hereinafter simply referred to as “frozen soil temperature”) is calculated. The calculation of the frozen soil temperature is because the temperature distribution in the frozen soil is usually almost linear. For example, the surface temperature of the freezing pipe 13 (ie, brine temperature) and the surface temperature of the frozen soil 21 (ie, between An average temperature at the boundary temperature (eg 0 ° C.) can be used as the frozen soil temperature.

Actually, the frozen soil temperature cannot be accurately obtained by the simple formula as described above due to the arrangement of the plurality of freezing tubes 13, but the method for calculating the frozen soil temperature from the frozen soil temperature distribution and the frozen soil thickness is as follows. For example, a method described on page 40 of “Ground freezing method-from planning and design to construction” (issued by the Japan Construction Mechanization Association in February 1982) is known.

The frozen soil strength calculating means 55 calculates the frozen soil strength from the frozen soil temperature. Frozen soil strength is determined mainly by frozen soil temperature, ground soil quality, ground moisture content, salinity, etc. In general, if the soil quality, water content, or salinity is constant, the strength of frozen soil increases as the temperature of frozen soil decreases. Various studies have been conducted on the relationship between the frozen soil temperature and the frozen soil strength. For example, “Soil Freezing Method-From Planning / Design to Construction” for each soil type and moisture content (Japan Construction Mechanization Association, 1982) Monthly issue), page 35.

The relationship between the frozen soil temperature and the frozen soil strength is stored in the ground information database 75 in advance, and the frozen soil strength calculating means 55 calculates the frozen soil strength from the frozen soil temperature based on the ground information on the construction site set in advance. Can be calculated. This frozen soil strength is usually set sufficiently small in consideration of the safety factor.

The frozen soil maximum stress calculating means 57 calculates the maximum stress acting on the frozen soil when the frozen soil is used. The types of stress to be calculated are generally compressive stress, bending stress and shear stress. From the load conditions and support conditions such as earth pressure and water pressure acting on the frozen soil, and the geometric conditions of the frozen soil including the frozen soil thickness. Can be calculated. A general formula of structural mechanics can be used for the calculation.

The frozen soil stress comparison means 59 compares the calculated frozen soil strength with the maximum frozen soil stress.

The optimum frozen soil temperature calculating means 63 calculates the optimum frozen soil temperature from the frozen soil maximum stress when the frozen soil strength exceeds the frozen soil maximum stress as a result of the comparison by the frozen soil stress comparing means 59. That is, contrary to the frozen soil strength calculating means 55, the optimum frozen soil temperature is calculated from the frozen soil maximum stress using the relationship between the frozen soil temperature and the frozen soil strength stored in the ground information database 75 in advance.

The optimum brine temperature calculation means 65 calculates a necessary brine temperature so that the average temperature in the range of the frozen soil thickness becomes the calculated optimum frozen soil temperature. In other words, contrary to the frozen soil temperature calculation means 53, for example, the “freezing method of ground-from planning / design to construction” (Japan Construction Mechanization Association, published in February 1982) can be frozen by the method described on page 40. The surface temperature of the tube 13 is calculated, and this is set as the optimum brine temperature.

The heat conduction osmotic flow coupling analysis means 67 uses a numerical calculation method such as a finite element method (hereinafter referred to as “FEM” (Finite-Element Method)), etc. The temperature distribution of the ground can be calculated. That is, it is possible to obtain a temporal change in the temperature distribution of the surrounding ground when the frozen tube set in the analysis is set to a predetermined temperature (that is, the set brine temperature). In addition, when the seepage flow of groundwater can be ignored, it can be substituted by a heat conduction analysis means.

When the brine temperature is changed, the frozen soil thickness calculation means 69 calculates the frozen soil thickness after the time required for the brine temperature to actually change to the set temperature (hereinafter referred to as “delay time”). To do. That is, since the frozen soil thickness increases during the delay time after changing the brine temperature, the delay time elapses from the temperature distribution after the delay time associated with the change of the brine temperature calculated by the heat conduction osmotic flow coupling analysis means 67. Calculate post-frozen soil thickness.

The maximum stress correction means 71 considers the frozen soil thickness after the lapse of the delay time, calculates the frozen soil maximum stress after the lapse of the delay time, and corrects the frozen soil maximum stress calculated by the frozen soil maximum stress calculation means 57 (hereinafter corrected). The maximum frozen soil stress is referred to as “corrected frozen soil maximum stress”).

The brine temperature control means 73 controls the brine temperature in the brine cooling circulation device 5. That is, in the brine cooling / circulation device 5, the brine temperature is controlled by the brine temperature control means 73 except for setting the initial temperature of the brine.

The ground information database 75 holds information related to the relationship between the frozen soil temperature and the frozen soil strength for each soil quality, moisture content, and salinity concentration.

Next, details of the operation of the freezing apparatus 1 will be described with reference to FIGS. 4 to 6. FIG. 4A and FIG. 4B are flowcharts showing the processing procedure of the freezing apparatus 1.

As shown in FIG. 4A, the control device 3 acquires the ground temperature data 23 from the thermometer 17 and calculates the temperature distribution of the ground (step 101). The installation position of the thermometer 17 is set in advance.

Next, the frozen soil thickness is calculated (step 102). The frozen soil thickness is calculated by the frozen soil thickness calculating means 51. That is, the surface temperature of the frozen soil 21 (that is, the boundary temperature between the frozen soil 21 and the non-frozen ground, which is normally about −2 ° C. to −5 ° C.) is set in advance, and the distribution position of the surface temperature of the frozen soil 21 The frozen soil thickness is calculated from the distance, assuming that the frozen soil 21 is between the tube and the freezing pipe 13.

Next, the brine temperature data 25 which is the temperature of the circulating brine is acquired from the brine cooling / circulating device 5, and the brine temperature is measured (step 103). The brine temperature is measured by, for example, a brine tank provided in the brine cooling / circulating device 5.

In addition, in order to shorten the frozen soil service period and to obtain the effects of the present invention more remarkably, the initial brine temperature is desirably about −65 ° C. to −35 ° C., which is lower than before. FIG. 5 is a diagram showing the relationship between the frozen soil thickness and time. For example, line O shows the change in frozen soil thickness due to the previous brine temperature of −30 ° C., and line R shows the change in frozen soil thickness at the brine temperature of −50 ° C. As shown in FIG. 5, by lowering the brine temperature, the thickness of the frozen soil increases rapidly, so that the construction period can be shortened.

Next, the frozen soil temperature calculating means 53 calculates the frozen soil temperature (step 104). That is, the ground temperature distribution is obtained based on the ground temperature data 23 measured by the thermometer 17, and the frozen soil temperature within the range of the frozen soil thickness calculated by the frozen soil thickness calculating means 51 from the ground temperature distribution and the arrangement of the freezing pipe 13. Is calculated.

Next, the frozen soil strength calculating means 55 calculates the frozen soil strength (step 105). That is, ground information (for example, soil quality and salinity concentration) of the frozen soil formation ground is set in advance, and the frozen soil strength at the frozen soil temperature calculated by the frozen soil temperature calculation means 53 at the corresponding soil quality and salinity concentration is set in the ground information database. Read from 75.

Next, the frozen soil maximum stress calculation means 57 calculates the frozen soil maximum stress (step 106). The types of stress to be calculated are generally compressive stress, bending stress and shear stress. From the load conditions and support conditions such as earth pressure and water pressure acting on the frozen soil, and the geometric conditions of the frozen soil including the frozen soil thickness. Can be calculated. A general formula of structural mechanics can be used for the calculation.

Next, the frozen soil stress comparing unit 59 compares the frozen soil maximum stress calculated by the frozen soil maximum stress calculating unit 57 with the frozen soil strength calculated by the frozen soil strength calculating unit 55 and considering the safety factor (step 107). ). As a result of the comparison, when the frozen soil maximum stress is larger than the frozen soil strength, that is, when the frozen soil is not yet formed to a usable level, the process from step 101 is repeated (step 108). In addition, the repetition period to step 101 may be determined according to the processing speed of the computer, or may be, for example, every hour. The process from step 101 to step 107 in a state where the frozen soil is not yet available corresponds to the change of the frozen soil thickness between oa in FIG.

When the maximum frozen soil stress is smaller than the frozen soil strength, that is, when the frozen soil is formed to be usable (in FIG. 5, the frozen soil thickness exceeds T ₀ ), the optimum frozen soil temperature calculating means 63. Thus, the optimum frozen soil temperature is calculated (step 110). The optimal frozen soil temperature is the average temperature of frozen soil.

The optimal frozen soil temperature is the highest frozen soil temperature in a range where the frozen soil strength does not fall below the maximum frozen soil stress. Frozen soil strength such as compressive strength, shear strength, and bending strength decreases as the frozen soil temperature increases. For this reason, the frozen soil temperature for obtaining the minimum frozen soil strength required for frozen soil is the optimum frozen soil temperature while maintaining the load resistance performance of frozen soil. Therefore, if the frozen soil thickness increases, even if the frozen soil temperature is high, a frozen soil strength that does not exceed the maximum frozen soil stress can be obtained. Therefore, the optimal frozen soil temperature increases as the frozen soil thickness increases.

In FIG. 5, the use of frozen soil can be started after the time t _{0 has} elapsed. Incidentally, a conventional method, the method is not considering the permafrost intensity change due to frozen ground temperature, frozen ground until the _second thickness T ₂ can not be started serviced, in brine temperatures Consequently -30 ° C., the time t _a up to start of service the required, even brine temperature of -50 ° C., takes time t _b to start of service (in this case, the change in frozen ground thickness proceeds with o point -a point -d point).

Next, the optimum brine temperature calculation means 65 calculates the optimum brine temperature (step 111). The optimum brine temperature calculated | required by the above is the highest brine temperature for the frozen soil range to have the minimum intensity | strength required in the actual frozen soil thickness.

When the brine temperature delay correction described later is not performed, the brine cooling circulation device 5 is controlled so that the brine temperature in the brine cooling circulation device 5 becomes the above-described optimum brine temperature (steps 112 and 117). That is, the brine temperature is raised so that the growth of frozen soil thickness is suppressed and the required minimum strength is obtained.

For example, in FIG. 5, line S indicates the change in frozen soil thickness at −40 ° C. from point a. When the brine temperature is changed from −50 ° C. to −40 ° C. at point a, the growth of frozen soil thickness is suppressed (change in frozen soil thickness proceeds from point o to point a to point b).

Furthermore, the line T shows the change of the frozen soil thickness at −30 ° C. from the point b. After changing the brine temperature from -50 ° C. to -40 ℃ at a point, the frozen soil thickness reaches _{T 1,} is changed from -40 ℃ brine temperature at the point b to -30 ° C.. Therefore, the growth of the frozen soil thickness is further suppressed (the change of the frozen soil thickness proceeds from the point o, the point a, the point b, and the point c). In this way, by changing (increasing) the brine temperature as the thickness of the frozen soil increases, the operation of the frozen soil can be started in the shortest time, while maintaining the required load resistance of the frozen soil (the strength of the frozen soil as a whole), and thereafter The formation of unnecessary frozen soil can be suppressed.

That is, in FIG. 5, T ₀ is the minimum required frozen soil thickness that satisfies the load resistance performance of frozen soil when the brine temperature is −50 ° C., and T ₁ and T ₂ are the brine temperatures of −40 ° C., respectively. The minimum required frozen soil thickness that satisfies the required load bearing performance at −30 ° C. is shown. Thus, when the relationship between the frozen soil temperature and the frozen soil strength is taken into consideration, the required frozen soil thickness changes according to the frozen soil temperature, and the usable frozen soil thickness changes accordingly.

Although FIG. 5 shows an example in which the brine temperature is changed for each frozen soil thickness of T ₀ and T ₁ , the brine temperature can be changed at regular intervals. For example, the brine temperature change time after t ₀ is set to every hour, and the optimum brine temperature can be set from the frozen soil thickness at that time every hour.

Next, brine temperature delay correction will be described. The brine temperature delay correction is a correction of the brine temperature in the case where the time until the actual brine temperature changes is taken into account after changing the setting of the brine temperature.

FIG. 6 is a diagram showing the relationship between the brine temperature and time. When the brine set temperature 81 is changed from θ ₀ to θ _{1 at the} brine temperature change point 85, the actual brine temperature measured value 83 (used as the brine temperature data 25) changes gradually thereafter. If the point at which the brine set temperature 81 and the brine temperature measured value 83 substantially coincide is the brine temperature change end point 87, the brine temperature delay time is the time required from the brine temperature change point 85 to the brine temperature change end point 87. Point to.

That is, even if the brine temperature is changed to the optimum brine temperature, the frozen soil thickness continues to increase during the brine temperature delay time, so when the brine temperature finishes changing, the optimum brine temperature has already changed. Yes. In addition, when the brine temperature is raised, the temperature distribution in the frozen soil does not become a monotonous temperature distribution, and the other part may be lower in temperature than the vicinity of the freezing pipe surface. In some cases, the frozen soil temperature (the average temperature in the frozen soil) remains on the lower temperature side than the frozen soil temperature calculated from the brine temperature.

In such a situation, the frozen soil has a load-bearing performance more than necessary. The brine temperature delay correction is to correct the optimum brine temperature taking into account the frozen soil thickness and the frozen soil temperature after the brine temperature delay time elapses as the optimum brine temperature at the time of the brine temperature change point 85.

Hereinafter, the flow of brine temperature delay correction will be described. As shown in FIG. 4B, the control device 3 uses the heat conduction osmotic flow coupling analysis means 67 to calculate the temporal change of the ground temperature distribution (frozen soil thickness and frozen soil temperature) by calculation (step 113). That is, the ground temperature distribution is calculated by combining heat conduction analysis and groundwater seepage flow by FEM from the brine temperature, the freezing pipe installation position, the ground information, and the like.

FIG. 7 shows the heat conduction osmotic flow analyzed by the heat conduction analysis and the groundwater osmotic flow by the FEM from the brine temperature, the freezing pipe installation position, the ground information, etc. It is a figure which shows the example 89 of an analysis. The color shading in FIG. 7 indicates the temperature distribution of the ground, and the dark color portion indicates the low temperature portion. In other words, the dark colored part showing the temperature below a certain temperature is frozen soil. In addition, the arrow X in a figure shows the flow direction of groundwater, and when an osmotic flow is considered, it turns out that the low temperature part has shifted to the downstream of groundwater.

Next, the frozen soil thickness calculation means 69 calculates the frozen soil thickness after the lapse of the delay time (step 114). The delay time is empirically determined in advance according to the change range of the brine temperature, the scale of the frozen soil, and the like. That is, the time-dependent change of the frozen soil thickness until the delay time elapses is calculated by the heat conduction osmotic flow coupling analysis means 67 from the current frozen soil situation, and is calculated as the frozen soil thickness after the delay time elapses. As the calculated brine temperature within the delay time, the brine temperature before the temperature change can be used, and the average value of the brine temperature before and after the change can also be used.

Next, the maximum stress correction means 71 corrects the maximum frozen soil stress (step 115). That is, the frozen soil temperature is calculated from the frozen soil thickness after the delay time by the same method as the frozen soil temperature calculating means 53, and the frozen soil temperature is calculated from the calculated frozen soil temperature after the delayed time and the frozen soil thickness after the delayed time. In the same manner as the maximum stress calculation means 57, the maximum frozen soil stress after the lapse of the delay time is calculated. The frozen maximum stress calculated in step 106 is corrected based on the calculated maximum frozen soil stress after the lapse of the delay time (hereinafter, the corrected frozen maximum stress is simply referred to as “corrected frozen soil maximum stress”). That is, the frozen ground maximum stress calculated in step 106 is replaced with the corrected frozen ground maximum stress.

Next, an optimum brine temperature is calculated after the delay time has elapsed (step 116). In other words, using the frozen maximum soil stress replaced with the corrected maximum frozen soil stress, the optimum frozen soil temperature calculating means 63 and the optimum brine temperature calculating means 65 recalculate the optimum brine temperature taking the delay time into account.

Next, the brine cooling / circulating device 5 is controlled so that the brine temperature in the brine cooling / circulating device 5 becomes the above-mentioned recalculated optimum brine temperature (step 117).

If the use of frozen soil is not completed, the process returns to step 101 and the above steps are repeated (step 118). In addition, the repetition period to step 101 may be determined according to the processing speed of the computer, or may be, for example, every hour.

As described above, according to the freezing apparatus 1 according to the present embodiment, it is possible to obtain a freezing apparatus that can use frozen soil at an early stage without unnecessarily growing frozen ground. In particular, as the initial brine temperature is set lower, the effect of increasing the frozen soil growth rate due to the decrease in the brine temperature and the increase in frozen soil strength due to the decrease in the frozen soil temperature can be obtained. Obtainable.

Also, by calculating the frozen soil temperature and obtaining the frozen soil strength from the frozen soil temperature, it is possible to know the minimum necessary frozen soil thickness according to the frozen soil temperature. Because the brine temperature is controlled so that the frozen soil strength can be obtained, the operation time of the frozen soil can be remarkably advanced, and the frozen soil can be grown more than necessary when the frozen soil is used while maintaining the required load resistance of the frozen soil. Therefore, the cooling energy of the brine can be suppressed, and the frost heaving phenomenon and the freezing expansion pressure can be reduced. In other words, in determining whether or not frozen soil can be used, by using the relationship between frozen soil temperature and frozen soil strength, the thickness of frozen soil that can be used at each point in time can be calculated, and the shortest frozen soil operating time can be known. Can be managed optimally.

In addition, if the delay time of the brine temperature is taken into account, unnecessary growth of frozen soil accompanying the delay in the brine temperature can be suppressed, and the brine temperature can be effectively controlled.

Next, a frozen soil calculation system 90 according to the second embodiment will be described. Here, in this Embodiment, about the component which show | plays the same function as the freezing apparatus 1, the code | symbol same as FIGS. 1-3 is attached | subjected and the overlapping description is avoided.

In FIG. 8, the frozen soil calculation system 90 has the same function as the freezing device 1, but the freezing device 1 uses actual measurement data from the thermometer 17 and the like, whereas the frozen soil calculation system 90 performs all of these. Predictive calculation is performed by a computer or the like.

The frozen soil calculation system 90 mainly includes a control device 3, a heat conduction osmotic flow coupling analysis device 91, a display device 99, and the like. The control device 3, the heat conduction osmotic flow coupling analysis device 91, and the display device 99 are connected to each other, the data 95 from the heat conduction osmotic flow coupling analysis device 91 is processed by the control device 3, and the data from the control device 3 is further processed. 97 is processed by the heat conduction osmotic flow coupling analysis device 91. Display data 93 from the heat conduction osmotic flow coupling analysis device 91 is transmitted to the display device 99, and various calculation results and the like are displayed on the display device 99.

The control device 3 is the same as that used in the freezing device 1, but the function of the heat conduction osmotic flow coupling analysis means 67 in the control device 3 can be given to the heat conduction osmotic flow coupling analysis device 91. . Hereinafter, the heat conduction osmotic flow coupling analysis means 67 will be described as having the same function in the heat conduction osmotic flow coupling analysis device 91, not the control device 3. The hardware configuration of the computer that realizes the heat conduction osmotic flow coupling analysis device 91 is the same as that of the control device 3 (see FIG. 2), and the description thereof is omitted.

Here, a finite element analysis program or the like can be used for the heat conduction osmotic flow coupled analysis device 91. If the groundwater flow is negligible, a heat conduction analysis device can be used instead.

Next, the operation of the frozen soil calculation system 90 will be described in detail with reference to FIG. First, the installation conditions, the ground conditions, the freezing conditions, etc. of the freezing pipe are input and set in the heat conduction osmotic flow coupled analysis device 91 (step 201). The freezing tube installation conditions include information such as the freezing tube installation position, the number of the freezing tubes, and the diameter of the freezing tube. The ground condition includes information such as soil quality, water content, salinity concentration, initial ground temperature, etc. in the analysis range. The freezing condition includes information such as circulating brine temperature and brine flow rate. In addition, the flow rate of the seepage flow of groundwater, the thermal conductivity coefficient of the ground, specific heat, etc. are set in advance.

Next, the FEM analyzes the ground heat conduction analysis and the groundwater infiltration flow simultaneously (step 202). The ground temperature distribution is calculated by the analysis, and thereby the temporal change of the ground temperature and the frozen soil thickness can be calculated (step 203). Step 202 and step 203 are based on the same function as the heat conduction osmotic flow coupling analysis means 67 in the freezing apparatus 1.

Next, at each calculation time, ground temperature, frozen soil thickness, brine temperature data, and the like are transmitted to the control device 3 (step 204). That is, the calculated values analyzed by the heat conduction osmotic flow coupling analysis device 91 corresponding to the ground temperature data 23 and the brine temperature data 25 in the freezing device 1 are transmitted to the control device 3. As the frozen soil thickness and the frozen soil temperature, the calculated values obtained by the heat conduction osmotic flow coupling analysis device 91 can be directly used, or the control device 3 can calculate the frozen soil thickness calculation means 51 and the frozen soil from the ground temperature data. You may calculate by the temperature calculation means 53. FIG.

Next, the control device 3 calculates the frozen soil strength from the ground information database 75 from the ground temperature or the like (or the frozen soil temperature or the frozen soil thickness calculated from the ground temperature or the like) by the frozen soil strength calculating means 55 (step 205). . Thereafter, processing from step 206 to step 212 is performed by the same method as the control device 3 (corresponding to step 106 to step 112) in the freezing device 1, and the optimum brine temperature is calculated.

When the brine temperature delay correction is not performed, the calculated optimum brine temperature is transmitted to the heat conduction osmotic flow coupled analysis device 91 (step 218), and the heat conduction osmotic flow coupled analysis device 91 is set for calculation. The brine temperature is changed to the optimum brine temperature and further analysis is continued (step 219).

When the brine temperature delay correction is performed, the heat conduction osmotic flow coupling analysis device 91 calculates the frozen soil thickness after the delay correction (steps 213 to 214). The delay time is empirically determined in advance according to the change range of the brine temperature, the scale of the frozen soil, and the like. Steps 213 to 214 correspond to the processing by the heat conduction osmotic flow coupling analysis means 67 and the frozen soil thickness calculation means 69 after the lapse of time in the freezing apparatus 1, and the processing is performed in the same manner. The heat conduction osmotic flow coupling analysis device 91 transmits the frozen soil thickness to the control device 3 after the calculated delay time has elapsed (step 215).

The control device 3 calculates the corrected frozen soil maximum stress based on the calculated frozen soil thickness after the lapse of the delay time, and corrects the optimum brine temperature (steps 216 to 217). Note that steps 216 to 217 correspond to the processing by the maximum stress correction means 71, the optimum frozen soil temperature calculation means 63, and the optimum brine temperature calculation means 65 of the freezing apparatus 1, and are processed in the same manner.

Finally, the corrected optimum brine temperature is transmitted to the heat conduction osmotic flow coupling analysis device 91, and the heat conduction osmotic flow coupling analysis device 91 changes the calculated brine temperature to the optimum brine temperature for further analysis. (Steps 218 to 219). Note that the change period of the brine temperature may be in accordance with the processing speed of the computer, or may be performed every hour and every certain calculation time.

According to the frozen soil calculation system 90 according to the second embodiment, it is possible to perform prediction analysis on the formation of frozen soil before construction, optimization of the installation location of the freezing pipe, optimization of the brine temperature setting, and the frozen soil It is possible to know in advance the in-service start time and the like, and it is possible to obtain conditions that allow the frozen soil to be used in an early stage without unnecessarily growing the frozen soil.

In addition, when using the “replacement method” in which a part of the ground is replaced with a material with high thermal conductivity for the efficient formation of frozen soil, the placement of frozen pipes and the formation of frozen soil are predicted, which is optimal for this. The brine temperature can be set. Also, in order to know the ground temperature distribution in more detail at the actual construction site, it is necessary to increase the number of thermometers 17 installed, but there are some disadvantageous parts (such as parts where the formation of frozen soil is delayed) in advance. If it can be known, the thermometer 17 can be installed by carefully selecting the site, the number of thermometers 17 installed during construction can be reduced, and the optimum brine temperature can be controlled.

In addition, this frozen soil calculation system 90 is used in combination with the freezing device 1 at the time of actual frozen soil formation, while correcting the deviation between the actual measurement value and the calculated value at each time point (for example, correcting the set value such as the flow velocity of groundwater seepage flow). By performing the analysis, a more reliable prediction result can be obtained.

As mentioned above, although embodiment of this invention was described referring an accompanying drawing, the technical scope of this invention is not influenced by embodiment mentioned above. It is obvious for those skilled in the art that various modifications or modifications can be conceived within the scope of the technical idea described in the claims, and these are naturally within the technical scope of the present invention. It is understood that it belongs.

For example, in FIG. 5, the brine temperatures corresponding to the lines R, S, and T are set to −50 ° C., −40 ° C., and −30 ° C., but the initial temperature of the brine may be any temperature, The change width of the brine temperature need not be + 10 ° C. Furthermore, the number of times the brine temperature is changed when the frozen soil is used is not limited to two, and it is desirable to control it more finely. Furthermore, the same effect can be obtained by controlling not only the brine temperature but also the flow rate of the brine.

Further, in the frozen soil calculation system 90, the heat conduction osmotic flow coupling analysis device 91 and the control device 3 may be implemented by a single computer.

Schematic which shows the freezing apparatus 1 concerning this Embodiment. FIG. 3 is a hardware configuration diagram of a computer that implements the control device 3. FIG. 2 is a schematic configuration diagram of a control device 3. The flowchart which shows the process sequence of the freezing apparatus. The flowchart which shows the process sequence of the freezing apparatus. The figure which shows the relationship between frozen soil thickness and time. The figure which shows a brine temperature delay time. The figure which shows the heat conduction osmotic flow coupled analysis example 89. Schematic which shows the frozen ground calculation system 90 concerning 2nd Embodiment. The flowchart which shows the process sequence of the frozen soil calculation system 90. The flowchart which shows the process sequence of the frozen soil calculation system 90. The figure which shows construction, such as an underground junction part of a shield machine.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ......... Freezing device 3 ... Control device 5 ... Brine cooling circulation device 7 ... Data collection device 8 ... Display device 9 ... Input side piping 11 ... Out side piping 13 ... ... Freezing tube 15 ...... Temperature measuring tube 17 ...... thermometer 19 ...... ground 21 ...... frozen soil 23 ...... ground temperature data 25 ......... brine temperature data 27 ......... data 28 ......... display Data 29... Optimum brine temperature data 90... Frozen earth calculation system 91... Heat conduction osmotic flow coupling analysis device 93... Display data 95. ……… Shield machine 303 ……… Freezing pipe 305 ……… Frozen soil 307 ……… Shield tunnel

Claims (11)

A freezing pipe buried in the ground,
A plurality of thermometers embedded around the freezing tube;
A brine cooling and circulating device for flowing brine at a predetermined temperature to the freezing pipe;
Using the ground temperature data measured by the thermometer and the brine temperature data measured by the brine cooling circulation device, the optimum brine temperature is calculated from the relationship between the frozen soil temperature and the frozen soil strength, A control device for controlling the brine cooling and circulation device so as to circulate the brine at the optimum brine temperature;
A freezing apparatus comprising: The controller is
The frozen soil thickness calculating means for calculating the frozen soil thickness from the ground temperature data measured by the thermometer, and the installation position of the thermometer,
A frozen soil temperature calculating means for calculating a frozen soil temperature from the brine temperature data measured by the brine cooling and circulation device and the frozen soil thickness;
Frozen soil strength calculating means for calculating frozen soil strength from the frozen soil temperature;
Frozen soil maximum stress calculating means for calculating the frozen soil maximum stress generated in the frozen soil when the frozen soil is in service, from the frozen soil thickness;
Frozen soil stress comparison means for comparing the frozen soil strength and the frozen soil maximum stress;
When the frozen soil strength is larger than the frozen soil maximum stress, optimal frozen soil temperature calculating means for calculating an optimal frozen soil temperature from the frozen soil maximum stress;
Optimal brine temperature calculating means for calculating an optimal brine temperature from the optimal frozen soil temperature and the frozen soil thickness;
The freezing apparatus according to claim 1, further comprising: The finite element method further comprises a heat conduction osmotic flow coupled analysis device capable of calculating the predicted frozen soil thickness by analyzing the heat conduction analysis and groundwater seepage flow from the brine temperature and the freezing pipe installation position.
The heat conduction osmotic flow coupled analysis device calculates a frozen ground thickness after a lapse of a delay time from a delay time until the brine temperature actually changes after controlling the brine temperature, and calculates a predicted frozen soil thickness after the lapse of the delay time. Comprising
3. The freezing apparatus according to claim 2, further comprising a maximum stress correcting unit that corrects the maximum frozen soil stress from the frozen soil thickness after the lapse of the delay time. Thermal conduction osmotic flow coupled analysis means that can calculate chronological changes of frozen soil thickness and frozen soil temperature by analyzing heat conduction analysis and groundwater seepage flow from the brine temperature and freeze tube installation position by finite element method. When,
Brine temperature control means for calculating an optimal brine temperature from the relationship between the frozen soil strength and the frozen soil temperature, using the frozen soil temperature calculated by the heat conduction osmotic flow coupled analysis means and the brine temperature;
A frozen soil calculation system, wherein the optimum brine temperature is applied to the heat conduction osmotic flow coupling analysis means to calculate a change over time in a frozen soil thickness and a frozen soil temperature. The brine temperature control means includes
Frozen soil strength calculating means for calculating the frozen soil strength from the frozen soil temperature calculated by the heat conduction osmotic flow coupling analysis means;
Frozen soil maximum stress calculating means for calculating the frozen soil maximum stress generated in the frozen soil when the frozen soil is in service, from the frozen soil thickness;
Frozen soil stress comparison means for comparing the frozen soil strength and the frozen soil maximum stress;
When the frozen soil strength is larger than the frozen soil maximum stress, optimal frozen soil temperature calculating means for calculating an optimal frozen soil temperature from the frozen soil maximum stress;
Optimal brine temperature calculating means for calculating an optimal brine temperature from the optimal frozen soil temperature and the frozen soil thickness;
The frozen soil calculation system according to claim 4, further comprising: From the delay time until the brine temperature actually changes after controlling the brine temperature, the frozen soil thickness calculating means for calculating the frozen soil thickness after the delay time has elapsed,
Maximum stress correcting means for correcting the frozen soil maximum stress from the frozen soil thickness after the lapse of time,
The frozen soil calculation system according to claim 5, further comprising: Installing a freezing tube and a thermometer;
Circulating brine to the freezing tube by a brine cooling and circulation device;
Measuring the ground temperature with the thermometer, and further measuring the temperature of the brine;
Using the ground temperature and the brine temperature to calculate an optimum brine temperature from the relationship between the frozen soil strength and the frozen soil temperature;
Circulating the brine at the optimum brine temperature to the freezing tube;
A freezing method comprising: The step of calculating the optimum brine temperature includes:
From the ground temperature data measured with the thermometer and the installation position of the thermometer, calculating the frozen soil thickness,
Calculating the frozen soil temperature from the brine temperature data measured by the brine cooling and circulation device and the frozen soil thickness;
Calculating the frozen soil strength from the frozen soil temperature;
Calculating frozen maximum stress generated in frozen soil when frozen soil is used from the frozen soil thickness;
Comparing the frozen soil strength with the frozen soil maximum stress;
Calculating the optimum frozen soil temperature from the frozen soil maximum stress when the frozen soil strength is greater than the frozen soil maximum stress;
Calculating an optimum brine temperature from the optimum frozen soil temperature and the frozen soil thickness;
The freezing method according to claim 7, further comprising: After calculating the optimum brine temperature, the brine temperature is controlled and then the actual brine temperature by analyzing the heat conduction analysis and groundwater seepage flow from the brine temperature and the freezing pipe installation position by the finite element method. Calculating the frozen soil thickness after the lapse of the delay time until
Correcting the frozen soil maximum stress from the frozen soil thickness after the lapse of time, and calculating the corrected frozen soil maximum stress;
Calculating the corrected optimum frozen soil temperature from the corrected frozen soil maximum stress;
Calculating a corrected optimum brine temperature from the corrected optimum frozen soil temperature and the frozen soil thickness after the lapse of the delay time;
Further comprising
9. The freezing method according to claim 8, wherein instead of the optimum brine temperature, a brine having the corrected optimum brine temperature is circulated through the freezing pipe. The program for functioning a computer as a control apparatus in any one of Claims 1-3. A program for causing a computer to function as the frozen soil calculation system according to any one of claims 4 to 6.