System and method for measuring unfrozen water content in frozen soil by pulse nuclear magnetic resonance (NMR)

A technology of nuclear magnetic resonance and unfrozen water, which is applied in the direction of using nuclear magnetic resonance for analysis, etc. It can solve the problems of high electromagnetic theoretical basis for operators, affecting measurement accuracy, and cumbersome measurement process, so as to improve measurement efficiency, good stability, Accurate and reliable results

Inactive Publication Date: 2011-04-06
HARBIN INST OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0008] In order to solve the cumbersome measurement process of the current unfrozen water content test in frozen soil, the operator needs to have a relatively high theoretical foundation in electromagnetics, and it is not easy to operate; for multi-temperature and multi-pressure working conditions, it is necessary to prepare multiple test pieces , making it exposed to normal temperature affects the measurement accuracy, providing a system and method for testing the unfrozen water content of frozen soil by using pulse nuclear magnetic resonance

Method used

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  • System and method for measuring unfrozen water content in frozen soil by pulse nuclear magnetic resonance (NMR)
  • System and method for measuring unfrozen water content in frozen soil by pulse nuclear magnetic resonance (NMR)
  • System and method for measuring unfrozen water content in frozen soil by pulse nuclear magnetic resonance (NMR)

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specific Embodiment approach 1

[0028] Specific implementation mode one: combine figure 1Describe this embodiment, the system of this embodiment includes frequency synthesizer 4, preamplifier 5, pulse generator 6 and control and display platform 8, it is characterized in that described system also includes radio frequency probe 1, permanent magnet N pole 2, Magnet S pole 3, shielding frame 7, refrigeration pipeline 20 and constant temperature control box, radio frequency probe 1, permanent magnet N pole 2 and magnet S pole 3 are all located in shielding frame 7, radio frequency probe 1 consists of soil test tube 15, ceramic tube 16 and pulse induction coil 17 constitute, constant temperature control box is made of nitrogen tank 9, pressure control valve 10, compressor 11, temperature control valve 12, temperature sensor 13 and pressure sensor 14, soil test tube 15 is contained in ceramic tube 16, One end of the temperature sensor 13 is set in the soil test tube 15, the temperature signal output end of the te...

specific Embodiment approach 2

[0032] Specific implementation mode two: combination figure 1 To describe this embodiment, the lower part of the ceramic tube 16 of this embodiment is provided with a refrigeration pipeline, and this structure is used to cool the test piece in the ceramic tube. Other components and connections are the same as those in the first embodiment.

specific Embodiment approach 3

[0033] Specific implementation mode three: combination figure 1 Describe this embodiment, the system of this embodiment also includes a fixed plug 21, the fixed plug 21 is set on the upper part of the ceramic tube 16, and the ceramic tube 16 is fixed in the pulse induction coil 17 through the fixed plug 21, and this structure is fixed during the test. Other components and connections are the same as those in the first embodiment.

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Abstract

The invention relates to a system and a method for measuring unfrozen water content in frozen soil by pulse NMR, aiming at the problems that, in the measurement of unfrozen water content, measuring procedures are complex, operators need relatively high electromagnetism theoretical basis, and operations are difficult; a plurality of test pieces are needed under multi-temperature and multi-pressure working conditions, and the test pieces are exposed in normal temperature to influence measurement precision. The system is characterized in that a soil testing tube is disposed in a ceramic tube; a temperature signal input end of a temperature sensor is disposed in the soil testing tube; a temperature signal output end of the temperature sensor is connected to the temperature signal input end of a temperature control valve. The method is characterized in that different relaxation time of solid water, combined water and free water in attenuation process are stipulated when free attenuation signals of magnetization intensity are fitted, so that the magnetic field intensity value corresponding to the free attenuation signals of magnetization intensity during the relaxation time can be obtained. The system and method of the present invention measure the unfrozen water content in frozen soil.

Description

technical field [0001] The invention relates to a system and method for testing the unfrozen water content of frozen soil. Background technique [0002] The unfrozen water content of frozen soil is one of the characteristic parameters of frozen soil. This parameter plays an important role in the design and calculation of many underground projects in frozen soil regions or seasonally frozen soil regions. At the same time, the unfrozen water content is the dominant factor affecting the changes in the physical and mechanical properties of frozen soil such as strength, modulus, damping, and Poisson's ratio, and a necessary index for thermal calculations. Therefore, quasi-intuitive measurement of unfrozen water content has important practical and theoretical significance. [0003] In the existing measurement of unfrozen water content in frozen soil: the time domain reflectometry determines the soil content by measuring the dielectric constant of the soil layer and according to t...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N24/08
Inventor 汤爱平王连发董鉴峰
Owner HARBIN INST OF TECH
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