CN106841291B - Device for measuring heat conduction coefficient of frozen soil in various directions and testing method thereof - Google Patents
Device for measuring heat conduction coefficient of frozen soil in various directions and testing method thereof Download PDFInfo
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Abstract
The invention provides a device for measuring the heat conduction coefficient of frozen soil in each direction, wherein a heating wire, an upper temperature measuring point, a lower temperature measuring point, a probe wall and filling sand are arranged in a heating temperature measuring probe of the device; the inner wall of the end part of the temperature probe is provided with temperature measuring points, and the probe wall of the temperature probe is filled with sand; the data line is connected with a heating temperature measuring probe and three temperature measuring probes through the handle pore canal and the probe mounting hole; the data line is connected with the data acquisition system. Meanwhile, a test method of the device for measuring the heat conduction coefficient of frozen soil in each direction is provided. The method has the advantages of being short in test time, convenient to calculate and the like, and provides a means for calculating the heat conductivity coefficients of frozen soil in all directions. The prediction error of the device is within 7.2% by comparing the calculated and measured values. The improvement of the precision can furthest improve the knowledge of the heat conduction performance of the frozen soil and provide guarantee for the selection of the heat parameters of the frozen soil temperature field.
Description
Technical Field
The invention belongs to the field of thermal parameter testing of frozen soil engineering, and relates to a device and a method for measuring the heat conductivity coefficients of frozen soil in different directions.
Background
Frozen soil is a four-phase system consisting of a soil framework, water, ice and gas, and is influenced by soil body fragmentation and structurality, and the soil body has stronger anisotropic property. The distribution of water in the unsaturated frozen soil at different temperatures is complex, and the water is influenced by cold source and soil macro-micro force, so that the unfrozen water in the soil body carries out nonlinear water migration. Thus, the coefficient of thermal conductivity of frozen earth exhibits a large anisotropy.
In conventional frozen soil temperature field calculations, the thermal conductivity is typically assumed to be isotropic or orthotropic, which is not in line with the frozen soil practice. The coefficient of heat conductivity of frozen soil in a certain direction is taken as the actual coefficient of heat conductivity of frozen soil, so that a certain error exists between the calculated value of the temperature field and the true value, and the error is about 10% -75% of the true value by numerical analysis. The current method for measuring the coefficient of heat conductivity of the frozen soil is divided into a steady state method and a transient state method, wherein the steady state method is used for measuring the average value of the coefficient of heat conductivity of the frozen soil in a certain area, and the transient state method is used for measuring the coefficient of heat conductivity of the frozen soil in a certain direction generally. Therefore, it is necessary to recognize the anisotropic property of the thermal conductivity of the frozen soil so as to correctly recognize and evaluate the temperature field distribution of the frozen soil. The method has important value for improving the temperature field calculation precision of the frozen soil engineering.
Disclosure of Invention
The invention aims to provide a device for measuring the heat conduction coefficient of the frozen soil and a testing method thereof, which realize the direct test of the heat conduction coefficient of the frozen soil, simplify the heat conduction coefficient of the soil body which needs to be tested for multiple times into one time, and solve the problems that a sample is easy to disturb and a test heat source is not unique.
In order to achieve the above object, the present invention provides a device for measuring the heat conduction coefficient of frozen soil, which is inserted into the soil body and connected with a data acquisition system, and is characterized in that: the device comprises a heating temperature probe, three temperature probes, a handle and a data line, wherein a heating wire, an upper temperature measuring point, a lower temperature measuring point, a probe wall and filling sand are arranged in the heating temperature probe; the inner wall of the end part of the temperature probe is provided with temperature measuring points, and the probe wall of the temperature probe is filled with sand; the handle comprises handheld cylinder and installation cylinder, and the round of handheld cylinder is connected with the round of installation cylinder, is provided with four probe mounting holes on the installation cylinder. The data line is connected with a heating temperature measuring probe and three temperature measuring probes through the handle pore canal and the probe mounting hole; the data wire consists of a group of heating wires for heating the temperature measuring probe, two groups of temperature measuring wires for heating the temperature measuring probe and three groups of temperature measuring wires for heating the temperature measuring probe; the data line is connected with the data acquisition system, so that the device for measuring the heat conduction coefficient of frozen soil is formed.
Meanwhile, a test method of the device for measuring the heat conduction coefficient of frozen soil in each direction is provided.
The method has the advantages of short test time, convenient calculation and the like, and provides a means for calculating the heat conductivity coefficients of frozen soil in all directions. The prediction error of the device is within 7.2% by comparing the calculated and measured values. The improvement of the precision can furthest improve the knowledge of the heat conduction performance of the frozen soil and provide guarantee for the selection of the heat parameters of the frozen soil temperature field.
Drawings
FIG. 1 is a device for measuring the heat transfer coefficient of frozen soil according to the present invention;
FIG. 2 is a schematic diagram of the composition of a heating temperature probe according to the present invention;
FIG. 3 is a schematic diagram of a temperature probe according to the present invention;
FIG. 4 is a left side view of the handle according to the present invention;
fig. 5 is a right side view of the handle according to the present invention.
In the figure:
1. heating temperature probe 2, temperature probe 3, handle 4, data line 11, heating wire
12. Upper temperature measuring point 13, lower temperature measuring point 14, probe wall 15, filling sand 21, temperature measuring point
31. Hand-held cylinder 32, mounting cylinder 33, probe mounting hole 34, duct 41 and heating wire
42. Temperature measuring wire
Detailed Description
The device for measuring the heat conduction coefficient of frozen soil and the testing method thereof are described with reference to the accompanying drawings.
The principle of the device for measuring the heat conduction coefficient of frozen soil in various directions is as follows: based on the application of the linear heat source method in the measurement of the heat conductivity coefficient, the device for measuring the heat conductivity coefficient of frozen soil in each direction and the testing method thereof are provided by measuring the heat conductivity coefficients of the frozen soil in the horizontal direction and the vertical direction.
The invention relates to a device for measuring the heat conduction coefficient of frozen soil, which is inserted into soil body and connected with a data acquisition system, and is characterized in that: the device comprises a heating temperature probe 1, three temperature probes 2, a handle 3 and a data wire 4, as shown in figure 1. A heating wire 11, an upper temperature measuring point 12, a lower temperature measuring point 13, a probe wall 14 and filling sand 15 are arranged in the heating temperature measuring probe 1; as shown in fig. 2. The inner wall of the end part of the temperature probe 2 is provided with a temperature measuring point 21, and the temperature probe 2 is also provided with a probe wall 14 and filling sand 15; as shown in fig. 3. The handle 3 is composed of a hand-held cylinder 31 and a mounting cylinder 32, wherein the circular surface of the hand-held cylinder 31 is connected with the circular surface of the mounting cylinder 32, and four probe mounting holes 33 are provided on the mounting cylinder 32, as shown in fig. 4 and 5. The data line 4 is connected with a heating temperature probe 1 and three temperature probes 2 through a pore canal 34 of the handle 3 and a probe mounting hole 33; the data wire 4 consists of a group of heating wires 41 for heating the temperature probe 1, two groups of temperature wires 42 for heating the temperature probe 1 and three groups of temperature wires 42 for heating the temperature probe 2; the data line 4 is connected with a data acquisition system, namely a device for measuring the heat conduction coefficient of frozen soil.
The invention relates to a testing method for measuring a frozen soil heat conduction coefficient device, which comprises the following steps:
1) Inserting a device for measuring the heat conduction coefficient of frozen soil in each direction into a sample to be measured vertically, and connecting a group of heating wires 41 in the data wire 4 with a heating power supply of a data acquisition system; connecting a temperature measuring wire 42 of the data wire 4 with a temperature acquisition instrument of the data acquisition system;
2) Numbering the temperature measuring points respectively, wherein the upper temperature measuring point and the lower temperature measuring point of the heating temperature measuring probe 1 are named as a and b respectively; three temperature probes 2 are designated as c, d, e in the clockwise direction.
3) Temperature data are collected, and after the reading of a temperature collector of a data collection system is stable, temperature values read by a heating temperature measuring probe 1 and a temperature measuring probe 2 are recorded and recorded as T j1 The method comprises the steps of carrying out a first treatment on the surface of the Then the heating power supply of the data acquisition system is used for heating and measuring temperatureThe heating wire inside the probe 1 is heated, and the heating start t is recorded 1 And end time t 2 The method comprises the steps of carrying out a first treatment on the surface of the Simultaneously recording the current intensity I and the output voltage U provided by a heating power supply of the data acquisition system; after the reading of the temperature acquisition instrument of the data acquisition system is stabilized again, the heating power supply of the data acquisition system is turned off, and the temperature values read by the heating temperature probe 1 and the temperature probe 2 are recorded and recorded as T j2 。
4) According to the temperature value T of the temperature measuring point a, b, c, d, e recorded by the data acquisition system a1 、T a2 ；T b1 、T b2 ；T c1 、T c2 ；T d1 、T d2 ；T e1 、T e2 The method comprises the steps of carrying out a first treatment on the surface of the Calculating the heat conductivity coefficient of the frozen soil by combining the formula (1), wherein the formula (1) is as follows:
in the formula (1), I is current intensity, A; u is output voltage, V; t is t 1 And t 2 Start and end times for the heating process; t (T) j1 And T j2 The temperature corresponding to the heating start and the heating end recorded for the temperature measuring point j is in DEG C; are obtained in step 3). According to the method, the heat conductivity coefficients of the frozen soil in all directions at different negative temperatures can be obtained, and guarantee is provided for the selection of the heat parameters of the frozen soil temperature field.
By comparing the remolded sample of the silty clay with the results of multiple multi-angle tests of a conventional steady state method, the error of the proposed device for measuring the heat conduction coefficient of frozen soil in the horizontal direction is kept within 4.4 percent, and the error in the vertical direction is kept within 7.2 percent. The improvement of the precision can furthest improve the knowledge of the heat conduction performance of the frozen soil and provide guarantee for the selection of the heat parameters of the frozen soil temperature field
The above description is only for the purpose of illustrating the present calculation process, and various changes and modifications will become apparent to those skilled in the art. Any modification, equivalent replacement, improvement, etc. made in accordance with the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (1)
1. The device comprises a heating temperature probe (1), three temperature probes (2), a handle (3) and a data wire (4), wherein a heating wire (11), an upper temperature measuring point (12), a lower temperature measuring point (13), a probe wall (14) and filling sand (15) are arranged in the heating temperature probe (1); the inner wall of the end part of each temperature measuring probe (2) is provided with a temperature measuring point (21), and the temperature measuring probes (2) are also internally provided with probe walls (14) and filling sand (15); the handle (3) is a handheld cylinder (31) and is connected with a mounting cylinder (32), and four probe mounting holes (33) are formed in the mounting cylinder (32); the data line (4) is connected with a heating temperature measuring probe (1) and three temperature measuring probes (2) through a duct (34) of the handle (3) and a probe mounting hole (33); the data wire (4) comprises a group of heating wires (41) for heating the temperature measuring probe (1), two groups of temperature measuring wires (42) for heating the temperature measuring probe (1) and three groups of temperature measuring wires (42) of the temperature measuring probe (2); connecting the data line (4) with a data acquisition system to form a device for measuring the heat conduction coefficient of frozen soil in each direction;
the method comprises the following steps:
1) Inserting a device for measuring the heat conduction coefficient of frozen soil in each direction into a sample to be measured vertically, and connecting a group of heating wires (41) in the data wire (4) with a heating power supply of a data acquisition system; a temperature measuring line (42) of the data line (4) is connected with a temperature acquisition instrument of the data acquisition system;
2) Numbering the temperature measuring points respectively, wherein the upper temperature measuring point and the lower temperature measuring point of the heating temperature measuring probe (1) are named as a and b respectively; the three temperature probes (2) are named as c, d and e according to the clockwise;
3) Temperature data are collected, and temperature values read by a heating temperature measuring probe (1) and a temperature measuring probe (2) are recorded after the reading of a temperature collecting instrument of a data collecting system is stable and recorded as T j1 The method comprises the steps of carrying out a first treatment on the surface of the Then the heating power supply of the data acquisition system is used for heating the heating wire inside the heating temperature probe (1), and the heating start is recorded and the heating start t is recorded 1 And end time t 2 The method comprises the steps of carrying out a first treatment on the surface of the Simultaneously recording the current intensity I and the output voltage U provided by a heating power supply of the data acquisition system; after the reading of the temperature acquisition instrument of the data acquisition system is stabilized again, the switch is closedClosing the heating power supply of the data acquisition system, recording the temperature values read by the heating temperature probe (1) and the temperature probe (2), and recording as T j2 ；
4) According to the temperature value T of the temperature measuring point a, b, c, d, e recorded by the data acquisition system a1 、T a2 ；T b1 、T b2 ；T c1 、T c2 ；T d1 、T d2 ；T e1 、T e2 The method comprises the steps of carrying out a first treatment on the surface of the Calculating the heat conductivity coefficient of the frozen soil by combining the formula (1), wherein the formula (1) is as follows:
in the formula (1), I is current intensity, A; u is output voltage, V; t is t 1 And t 2 Start and end times for the heating process; t (T) j1 And T j2 The temperature corresponding to the heating start and the heating end recorded for the temperature measuring point j is in DEG C; are obtained in step 3).
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| CN108226220A (en) * | 2017-12-28 | 2018-06-29 | 河海大学 | Temperature control anisotropic soil body heat physical property joint test device and test method |
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| CN110320234A (en) * | 2019-08-09 | 2019-10-11 | 天津城建大学 | A kind of measuring device and implementation method of bleeder soil body thermal coefficient |
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